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  • 1.
    Aspenström, Pontus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Integration of signalling pathways regulated by small GTPases and calcium2004In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1742, no 1-3, p. 51-58Article, review/survey (Refereed)
    Abstract [en]

    The Ras superfamily of small GTPases constitutes a large group of structurally and functionally related proteins. They function as signalling switches in numerous signalling cascades in the cell. During the recent years, an increased awareness of a communication between signalling systems employing Ras-like GTPases and signalling systems employing calcium has emerged. For instance, the intensity of the activation of Ras-like GTPases is regulated by calcium-dependent mechanisms, acting on proteins that facilitate the activation or inactivation of the small GTPases. Other Ras-like GTPases have a direct influence on calcium signalling by regulating the activity of certain calcium channels. In addition, several small GTPases collaborate with calcium signalling in regulating cellular processes, such as cell adhesion, cell migration and exocytosis.

  • 2.
    Badhai, Jitendra
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Fröjmark, Anne-Sophie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Davey, Edward J.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Schuster, Jens
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Dahl, Niklas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Ribosomal protein S19 and S24 insufficiency cause distinct cell cycle defects in Diamond-Blackfan anemia2009In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1792, no 10, p. 1036-1042Article in journal (Refereed)
    Abstract [en]

    Diamond-Blackfan anemia (DBA) is a severe congenital anemia characterized by a specific decrease of erythroid precursors. The disease is also associated with growth retardation, congenital malformations, a predisposition for malignant disease and heterozygous mutations in either of the ribosomal protein (RP) genes RPS7, RPS17, RPS19, RPS24, RPL5, RPL11 and RPL35a. We show herein that primary fibroblasts from DBA patients with truncating mutations in RPS19 or in RPS24 have a marked reduction in proliferative capacity. Mutant fibroblasts are associated with extended cell cycles and normal levels of p53 when compared to w.t. cells. RPS19 mutant fibroblasts accumulate in the G1 phase, whereas the RPS24 mutant cells show an altered progression in the S phase resulting in reduced levels in the G2/M phase. RPS19 deficient cells exhibit reduced levels of Cyclin-E, CDK2 and retinoblastoma (Rb) protein supporting a cell cycle arrest in the G1 phase. In contrast, RPS24 deficient cells show increased levels of the cell cycle inhibitor p21 and a seemingly opposing increase in Cyclin-E, CDK4 and CDK6. In combination, our results show that RPS19 and RPS24 insufficient fibroblasts have an impaired growth caused by distinct blockages in the cell cycle. We suggest this proliferative constraint to be an important contributing mechanism for the complex extra-hematological features observed in DBA.

  • 3.
    Bergström, Gunnel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Proteolytic modification of pig and rat liver pyruvate kinase including the phosphorylatable site1978In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 532, no 2, p. 259-267Article in journal (Refereed)
    Abstract [en]

    The phosphorylated or phosphate-accepting site of pyruvate kinase from pig and rat liver was removed without inactivation by incubation with subtilisin. At different time intervals the subtilisin was inactivated with phenylmethylsulfonyl fluoride and the amount of remaining phosphorylatable or phosphorylated sites of pyruvate kinase estimated by incubation with an excess of [32P]-ATP and protein kinase. It was found that to get the same rate of modification the subtilisin concentration required to modify unphosphorylated pyruvate kinase was approximately ten times higher than that used for removal of the phosphorylated site of phosphorylated site of phosphorylated enzyme. It was shown that the proteolytically-modified pyruvate kinase had an increased apparent Km for phosphoenolpyruvate without a change in V, when compared to unmodified unphosphorylated and phosphorylated pyruvate kinase. The removal of the phosphorylated site was not associated with loss of the allosteric sites for ATP and Fru-1,6-P2. The possibility that phosphorylation of the pyruvate kinase increases its degradation rate in vivo is briefly discussed.

  • 4.
    Berts, Alf
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Ball, Andrew
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Gylfe, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Hellman, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Suppression of Ca2+ oscillations in glucagon-producing alfa2-cells by insulin/glucose and amino acids1996In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1310, no 2, p. 212-216Article in journal (Refereed)
    Abstract [en]

    The cytoplasmic Ca2+ concentration ([Ca2+]i) was continuously monitored in single glucagon-producing α2-cells isolated from the mouse pancreas and later identified by immunostaining. Up to 60% of the α2-cells exhibited spontaneous [Ca2+]i oscillations (frequency 0.1–0.3/min) in a medium containing 3 mM glucose. In originating from a basal level of 60–100 nM, reaching peak values of 300–400 nM and promptly disappearing after blocking voltage-dependent Ca2+ channels with methoxyverapamil, the oscillations resembled those in insulin-releasing β-cells stimulated by glucose. The oscillatory activity was suppressed when combining elevation of glucose to 20 mM with the addition of 2–2000 ng/ml insulin. Whereas 10 mM of l-arginine or l-glycine transformed the oscillations into sustained elevation of [Ca2+];, there was no response to 1 mM tolbutamide or 0.1–1 mM γ-aminobutyric acid. The observations that α2-cells differ from islet cells secreting insulin and somatostatin in responding to adrenaline with mobilisation of intracellular calcium can be used for their rapid identification. It is suggested that the oscillations reflect periodic entry of Ca2+ due to variations of the membrane potential.

  • 5.
    Birnir, Bryndis
    et al.
    Department of Physiology, UCLA School of Medicine.
    Lee, H S
    Hediger, M A
    Wright, E M
    Expression and characterization of the intestinal Na+/glucose cotransporter in COS-7 cells.1990In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1048, no 1, p. 100-4Article in journal (Refereed)
    Abstract [en]

    Cells derived from the simian kidney, COS-7 cells, were transfected with a eucaryotic expression vector (pEUK-C1) containing the clone for the rabbit intestinal Na+/glucose cotransporter. Expression was monitored after transfection with lipofectin by measuring the initial rate of alpha-methylglucopyranoside (MeGlc) uptake. Cells transfected with vector containing the cDNA for the Na+/glucose cotransporter expressed Na(+)-dependent MeGlc transport. Neither control cells nor cells transfected with vector lacking cloned cDNA expressed the cotransporter. Na(+)-dependent MeGlc uptake into transfected cells was saturable (Km 150 microM), phlorizin-sensitive (Ki 11 microM), and inhibited by sugar analogs (D-glucose greater than MeGlc greater than D-galactose greater than 3-O-methyl-D-glucoside greater than D-allose much greater than L-glucose). Europium was able to mimic Na+ in driving MeGIC uptake. Finally, tunicamycin, an inhibitor of asparagine-linked glycosylation, inhibited the expression of Na(+)-dependent MeGlc transport 80%. We conclude that the rabbit intestinal Na+/glucose cotransporter expressed in COS-7 cell exhibits very similar kinetic properties to that in the native brush border and to that expressed in Xenopus oocytes. In addition, N-linked glycosylation appears to be important for functional expression of this membrane protein.

  • 6.
    Blikstad, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Shokeer, Abeer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Kurtovic, Sanela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Mannervik, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Emergence of a novel highly specific and catalytically efficient enzyme from a naturally promiscuous glutathione transferase2008In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1780, no 12, p. 1458-63Article in journal (Refereed)
    Abstract [en]

    Redesign of glutathione transferases (GSTs) has led to enzymes with remarkably enhanced catalytic properties. Exchange of substrate-binding residues in GST A1-1 created a GST A4-4 mimic, called GIMFhelix, with >300-fold improved activity with nonenal and suppressed activity with other substrates. In the present investigation GIMFhelix was compared with the naturally-evolved GSTs A1-1 and A4-4 by determining catalytic efficiencies with nine alternative substrates. The enzymes can be represented by vectors in multidimensional substrate-activity space, and the vectors of GIMFhelix and GST A1-1, expressed in kcat/Km values for the alternative substrates, are essentially orthogonal. By contrast, the vectors of GIMFhelix and GST A4-4 have approximately similar lengths and directions. The broad substrate acceptance of GST A1-1 contrasts with the high selectivity of GST A4-4 and GIMFhelix for alkenal substrates. Multivariate analysis demonstrated that among the diverse substrates used, nonenal, cumene hydroperoxide, and androstenedione are major determinants in the portrayal of the three enzyme variants. These GST substrates represent diverse chemistries of naturally occurring substrates undergoing Michael addition, hydroperoxide reduction, and steroid double-bond isomerization, respectively. In terms of function, GIMFhelix is a novel enzyme compared to its progenitor GST A1-1 in spite of 94% amino-acid sequence identity between the enzymes. The redesign of GST A1-1 into GIMFhelix therefore serves as an illustration of divergent evolution leading to novel enzymes by minor structural modifications in the active site. Notwithstanding low sequence identity (60%), GIMFhelix is functionally an isoenzyme of GST A4-4.

  • 7.
    Dahlqvist, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Endogenous substrates of protein kinase in rat liver cell sap under different dietary conditions1978In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 540, no 1, p. 13-23Article in journal (Refereed)
    Abstract [en]

    Liver cell sap from normally fed rats, rats fed with a high-carbohydrate diet and fasted rats was chromatographed on DEAE-cellulose (pH 7.0). The chromatogram from each diet group was analyzed for pyruvate kinase activity and endogenous substrates of cyclic AMP-stimulated protein kinase. The materials were pooled into five phosphorylatable fractions, in each of which phosphate incorporation at 0.1 mM and 1.0 mM [32P]ATP in the presence of cyclic AMP and protein kinase was determined. For characterization of the phosphorylatable components, thin-layer gel chromatography on Sephadex G-200 and polyacrylamide gel electrophoresis in detergent were used for determination of native and minimal molecular weights, respectively. Except for pyruvate kinase, eight components which incorporated at least 0.05 nmol of [32P]phosphate/g of liver were detected. The phosphorylation of four of them was stimulated by cyclic AMP. Their minimal molecular weights were 42000, 21000, 52000 and 49000. The component with a minimal molecular weight of 42000 seemed to have a native molecular weight of 160000. Both the 21000 and the 52000 component had a native molecular weight of about 110000-120000. The protein with a minimal molecular weight of 49000 could not be correlated with certainty to a native molecular weight. The proteins whose phosphorylation was not stimulated by cyclic AMP had minimal molecular weights of 54000, 39000, 34000 and 22000.

  • 8.
    Dinic, Jelena
    et al.
    Stockholms universitet, Wenner-Grens institut.
    Biverståhl, Henrik
    Stockholms universitet, Institutionen för biokemi och biofysik.
    Mäler, Lena
    Stockholms universitet, Institutionen för biokemi och biofysik.
    Parmryd, Ingela
    Stockholms universitet, Wenner-Grens institut.
    Laurdan and di-4-ANEPPDHQ do not respond to membrane-inserted peptides and are good probes for lipid packing2011In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1808, no 1, p. 298-306Article in journal (Refereed)
    Abstract [en]

    Laurdan and di-4-ANEPPDHQ are used as probes for membrane order, with a blue shift in emission for membranes in liquid-ordered (lo) phase relative to membranes in liquid-disordered (ld) phase. Their use as membrane order probes requires that their spectral shifts are unaffected by membrane proteins, which we have examined by using membrane inserting peptides and large unilamellar vesicles (LUVs). The transmembrane polypeptides, mastoparan and bovine prion protein-derived peptide (bPrPp), were added to LUVs of either lo or ld phase, up to 1:10 peptide/total lipid ratio. The excitation and emission spectra of laurdan and di-4-ANEPPDHQ in both lipid phases were unaltered by peptide addition. The integrity and size distribution of the LUVs upon addition of the polypeptides were determined by dynamic light scattering. The insertion efficiency of the polypeptides into LUVs was determined by measuring their secondary structure by circular dichroism. Mastoparan had an α-helical and bPrPp a β-strand conformation compatible with insertion into the lipid bilayer. Our results suggest that the presence of proteins in biological membranes does not influence the spectra of laurdan and di-4-ANEPPDHQ, supporting that the dyes are appropriate probes for assessing lipid order in cells.

  • 9.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Dahlqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Comparative kinetic studies on the L-type pyruvate kinase from rat liver and the enzyme phosphorylated by cyclic 3´, 5´-AMP-stimulated protein kinase1976In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 429, no 2, p. 374-382Article in journal (Refereed)
    Abstract [en]

    The kinetics of rat liver L-type pyruvate kinase (EC 2.7.1.40), phosphorylated with cyclic AMP-stimulated protein kinase from the same source, and the unphosphorylated enzyme have been compared. The effects of pH and various concentrations of substrates, Mg2+, K+ and modifiers were studied. In the absence of fructose 1, 6-diphosphate at pH 7.3, the phosphorylated pyruvate kinase appeared to have a lower affinity for phosphoenolpyruvate (K0.5=0.8 mM) than the unphosphorylated enzyme (K0.5=0.3 mM). The enzyme activity vs. phosphoenolpyruvate concentration curve was more sigmoidal for the phosphorylated enzyme with a Hill coefficient of 2.6 compared to 1.6 for the unphosphorylated enzyme. Fructose 1, 6-diphosphate increased the apparent affinity of both enzyme forms for phosphoenolpyruvate. At saturating concentrations of this activator, the kinetics of both enzyme forms were transformed to approximately the same hyperbolic curve, with a Hill coefficient of 1.0 and K0.5 of about 0.04 mM for phosphoenolpyruvate. The apparent affinity of the enzyme for fructose 1, 6-diphosphate was high at 0.2 mM phosphoenolpyruvate with a K0.5=0.06 muM for the unphosphorylated pyruvate kinase and 0.13 muM for the phosphorylated enzyme. However, in the presence of 0.5 mM alanine plus 1.5 mM ATP, a higher fructose 1, 6-diphosphate concentration was needed for activation, with K0.5 of 0.4 muM for the unphosphorylated enzyme and of 1.4 muM for the phosphorylated enzyme. The results obtained strongly indicate that phosphorylation of pyruvate kinase may also inhibit the enzyme in vivo. Such an inhibition should be important during gluconeogenesis.

  • 10.
    Eriksson, Jan W
    et al.
    Department of Medicine, University of Göteborg, Sahlgren's Hospital, Sweden.
    Wesslau, C
    Smith, U
    The cGMP-inhibitable phosphodiesterase modulates glucose transport activation by insulin1994In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1189, no 2, p. 163-167Article in journal (Refereed)
    Abstract [en]

    To assess the role of the cGMP-inhibitable phosphodiesterase (cGI-PDE) in the action of insulin on glucose transport, adipocytes from young, lean rats were preincubated for 20 min at 37 degrees C with and without OPC 3911, a specific inhibitor of cGI-PDE, and 3-O-methylglucose uptake was measured. Insulin-stimulated glucose transport was impaired by OPC 3911 (approximately 15%) and this impairment became more pronounced in the presence of the degradable cAMP-analogue 8-bromo-cAMP (approximately 45%). This analogue alone did not significantly decrease glucose transport. Furthermore, insulin sensitivity was impaired by the combination of OPC 3911 and 8-bromo-cAMP. Maximal insulin-stimulated glucose transport in adipocytes from aging, obese rats was affected similarly by OPC 3911 and 8-bromo-cAMP, suggesting that cGI-PDE activity is not markedly altered in this insulin-resistant state. In conclusion, cGI-PDE exerts a modulating effect on the stimulatory action of insulin on glucose transport. This effect is particularly pronounced when the cellular cAMP levels are elevated.

  • 11.
    Friederich, Malou
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Fasching, Angelica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Hansell, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Nordquist, Lina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Diabetes-induced up-regulation of uncoupling protein-2 results in increased mitochondrial uncoupling in kidney proximal tubular cells2008In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1777, no 7-8, p. 935-940Article in journal (Refereed)
    Abstract [en]

    We have previously reported increased O(2) consumption unrelated to active transport by tubular cells and up-regulated mitochondrial uncoupling protein (UCP)-2 expressions in diabetic kidneys. It is presently unknown if the increased UCP-2 levels in the diabetic kidney results in mitochondrial uncoupling and increased O(2) consumption, which we therefore investigated in this study. The presence of UCP-2 in proximal tubular cells was confirmed by immunohistochemistry and found to be increased (western blot) in homogenized tissue and isolated mitochondria from kidney cortex of diabetic rats. Isolated proximal tubular cells had increased total and ouabain-insensitive O(2) consumption compared to controls. Isolated mitochondria from diabetic animals displayed increased glutamate-stimulated O(2) consumption (in the absence of ADP and during inhibition of the ATP-synthase by oligomycin) compared to controls. Guanosine diphosphate, an UCP inhibitor, and bovine serum albumin which removes fatty acids that are essential for UCP-2 uncoupling activity, independently prevented the increased glutamate-stimulated O(2) consumption in mitochondria from diabetic animals. In conclusion, diabetic rats have increased mitochondrial UCP-2 expression in renal proximal tubular cells, which results in mitochondrial uncoupling and increased O(2) consumption. This mechanism may be protective against diabetes-induced oxidative stress, but will increase O(2) usage. The subsequently reduced O(2) availability may contribute to diabetes-induced progressive kidney damage.

  • 12.
    Gobl, Anders E
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Berg, Mikael
    Lopez-Egido, Juan R
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Öberg, Kjell
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Skogseid, Britt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Westin, Gunnar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Endocrine Surgery.
    Menin represses JunD-activated transcription by a histone deacetylase-dependent mechanism1999In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1447, no 1, p. 51-56Article in journal (Refereed)
    Abstract [en]

    Recently the multiple endocrine neoplasia type 1 (MEN-1) tumor suppressor gene was cloned. MEN-1 encodes a nuclear protein, called menin, of hitherto unknown function. In order to investigate the biological function of menin we employed the yeast two-hybrid system to identify menin-interacting proteins. Here we report that menin functions as a transcriptional repressor through interaction with the transcription factor JunD. The interaction is mediated via the N-terminal transcription activation domain of JunD, and the C-terminal part of menin. In transient co-transfection experiments, expression of menin leads to specific repression of JunD transcriptional activity, which is dependent on the integrity of the menin C-terminal region. C-Terminal truncations of the protein not only abolish repression, but increase JunD transcriptional activity, implying the existence of a functional domain separate from the JunD-binding region. Menin-mediated repression is relieved by the histone deacetylase inhibitor trichostatin A, indicating that deacetylation of histones is an essential component of this repression mechanism, as has recently been demonstrated for the retinoblastoma protein. Missense, in-frame deletions, frameshift and nonsense mutations lead to inactivation of menin or possibly to truncated proteins. This would result in loss of repression of menin/JunD target genes, as well as non-target genes through indirect mechanisms, deregulation of cellular growth control and endocrine tumorigenesis.

  • 13. Haj-Yasein, Nadia Nabil
    et al.
    Berg, Ole
    Jernerén, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Dept. of Pharmacology, University of Oxford.
    Refsum, Helga
    Nebb, Hilde I
    Dalen, Knut Tomas
    Cysteine deprivation prevents induction of peroxisome proliferator-activated receptor gamma-2 and adipose differentiation of 3T3-L1 cells.2017In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1862, no 6, p. 623-635, article id S1388-1981(17)30033-1Article in journal (Refereed)
    Abstract [en]

    Plasma cysteine is strongly associated with body fat mass in human cohorts and diets low in cysteine prevents fat accumulation in mice. It is unclear if plasma cysteine affects fat development or if fat accumulation raises plasma cysteine. To determine if cysteine affects adipogenesis, we differentiated 3T3-L1 preadipocytes in medium with reduced cysteine. Cells incubated in media with 10-20μM cysteine exhibited reduced capacity to differentiate into triacylglycerol-storing mature adipocytes compared with cells incubated with 50μM cysteine. Low cysteine severely reduced expression of peroxisome proliferator-activated receptor gamma2 (Pparγ2) and its target genes perlipin1 (Plin1) and fatty acid binding protein-4 (Fabp4). Expression of stearoyl-CoA desaturase-1 (Scd1), known to be repressed with cysteine depletion, was also reduced with low cysteine. Medium depletion of the essential amino acids leucine, valine, and isoleucine had only a modest effect on adipocyte specific gene expression and differentiation. Stimulation with the PPARγ agonist BRL-49653 or addition of a hydrogen sulfide donor enhanced differentiation of 3T3-L1 cells cultured in low cysteine. This demonstrates that the ability to induce PPARγ expression is preserved when cells are cultured in low cysteine. It therefore appears that cysteine depletion inhibits adipogenesis by specifically affecting molecular pathways required for induction of PPARγ expression, rather than through a general reduction of global protein synthesis. In conclusion, we show that low extracellular cysteine reduces adipocyte differentiation by interfering with PPARγ2 and PPARγ target gene expression. Our results provide further evidence for the hypothesis that plasma cysteine is a casual determinant for body fat mass.

  • 14.
    Henriksson, Gunnar
    et al.
    Department of Pulp and Paper Technique and Chemistry, Royal Institute of Technology, Stockholm, Sweden.
    Sild, Veljo
    Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia.
    Szabó, István J
    Pettersson, Göran
    Johansson, Gunnar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Biochemistry and Organic Chemistry.
    Substrate specificity of cellobiose dehydrogenase from Phanerochaete chrysosporium1998In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1383, no 1, p. 48-54Article in journal (Refereed)
    Abstract [en]

    Substrate structural mapping suggests that the catalytic site of cellobiose dehydrogenase from Phanerochaete chrysosporium forms a narrow cave with two hexose binding subsites, Kinetic data also show that beta-di or oligosaccharides are favored electron donors with respect to both KM and kcat. Surprisingly, thiocellobiose showed an even higher kcat than cellobiose, although the KM value was somewhat higher. The CDH was purified using an updated protocol.

  • 15.
    Henriksson, Richard
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Backman, Cristina M
    Harvey, Brandon K
    Kadyrova, Helena
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bazov, Igor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Shippenberg, Toni S
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    PDYN, a gene implicated in brain/mental disorders, is targeted by REST in the adult human brain2014In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1839, no 11, p. 1226-1232Article in journal (Refereed)
    Abstract [en]

    The dynorphin kappa-opioid receptor system is implicated in mental health and brain/mental disorders. However, despite accumulating evidence that PDYN and/or dynorphin peptide expression is altered in the brain of individuals with brain/mental disorders, little is known about transcriptional control of PDYN in humans. In the present study, we show that PDYN is targeted by the transcription factor REST in human neuroblastoma SH-SY5Y cells and that that interfering with REST activity increases PDYN expression in these cells. We also show that REST binding to PDYN is reduced in the adult human brain compared to SH-SY5Y cells, which coincides with higher PDYN expression. This may be related to MIR-9 mediated down-regulation of REST as suggested by a strong inverse correlation between REST and MIR-9 expression. Our results suggest that REST represses PDYN expression in SH-SY5Y cells and the adult human brain and may have implications for mental health and brain/mental disorders.

  • 16.
    Jernerén, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Garscha, Ulrike
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Hoffmann, Inga
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Hamberg, Mats
    Oliw, Ernst H
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Reaction mechanism of 5,8-linoleate diol synthase, 10R-dioxygenase, and 8,11-hydroperoxide isomerase of Aspergillus clavatus2010In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1801, no 4, p. 503-507Article in journal (Refereed)
    Abstract [en]

    Aspergilli express fusion proteins of an animal haem peroxidase domain with fatty acid dioxygenase (DOX) activity ( approximately 600 amino acids) and a functional or non-functional hydroperoxide isomerase/cytochrome P450 domain ( approximately 500 amino acids with EXXR and GPHXCLG motifs). 5,8-Linoleate diol synthases (LDS; ppoA) and 10R-DOX (ppoC) of Aspergillusnidulans and A. fumigatus belong to this group. Our objective was to determine the oxylipins formed from linoleic acid by A. clavatus and their mechanism of biosynthesis. A. clavatus oxidized linoleic acid to (8R)-hydroperoxylinoleic acid (8R-HPODE), (10R)-hydroperoxy-8(E),12(Z)-octadecadienoic acid (10R-HPODE), and to (5S,8R)-dihydroxy- and (8R,11S)-dihydroxylinoleic acids (DiHODE) as major products. This occurred by abstraction of the pro-S hydrogen at C-8 and antarafacial dioxygenation at C-8 or at C-10 with double bond migration. 8R-HPODE was then isomerized to 5S,8R-DiHODE and to 8R,11S-DiHODE by abstraction of the pro-S hydrogens at C-5 and C-11 of 8R-HPODE, respectively, followed by suprafacial oxygenation. The genome of A. clavatus codes for two enzymes, which can be aligned with >65% amino acid identity to 10R-DOX and 5,8-LDS, respectively. The 5,8-LDS homologue likely forms and isomerizes 8R-HPODE to 5S,8R-DiHODE. A third gene (ppoB) codes for a protein which carries a serine residue at the cysteine position of the P450 motif. This Cys to Ser replacement is known to abolish P450 2B4 catalysis and the hydroperoxide isomerase activity of 5,8-LDS, suggesting that ppoB of A. clavatus may not be involved in the biosynthesis of 8R,11S-DiHODE.

  • 17.
    Karlsson, Oskar
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Karolinska Inst, Dept Clin Neurosci, Ctr Mol Med, Sweden; Harvard TH Chan Sch Publ Hlth, Dept Environm Hlth, USA.
    Michno, Wojciech
    Ransome, Yusuf
    Hanrieder, Jörg
    MALDI imaging delineates hippocampal glycosphingolipid changes associated with neurotoxin induced proteopathy following neonatal BMAA exposure.2017In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1865, no 7, p. 740-746Article in journal (Refereed)
    Abstract [en]

    The environmental toxin β-N-methylamino-L-alanine (BMAA) has been proposed to contribute to neurodegenerative diseases. We have previously shown that neonatal exposure to BMAA results in dose-dependent cognitive impairments, proteomic alterations and progressive neurodegeneration in the hippocampus of adult rats. A high BMAA dose (460mg/kg) also induced intracellular fibril formation, increased protein ubiquitination and enrichment of proteins important for lipid transport and metabolism. The aim of this study was therefore to elucidate the role of neuronal lipids in BMAA-induced neurodegeneration. By using matrix assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS), we characterized the spatial lipid profile in the hippocampus of six month-old rats that were treated neonatally (postnatal days 9-10) with 460mg/kg BMAA. Multivariate statistical analysis revealed long-term changes in distinct ganglioside species (GM, GD, GT) in the dentate gyrus. These changes could be a consequence of direct effects on ganglioside biosynthesis through the b-series (GM3-GD3-GD2-GD1b-GT1b) and may be linked to astrogliosis. Complementary immunohistochemistry experiments towards GFAP and S100β further verified the role of increased astrocyte activity in BMAA-induced brain damage. This highlights the potential of imaging MS for probing chemical changes associated with neuropathological mechanisms in situ. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann.

  • 18. Kass, G E
    et al.
    Chow, S C
    Gahm, A
    Webb, Dominic-Luc
    Rolf Luft Center for Diabetes Research, Department of Endocrinology, Karolinska Institutet, Stockholm, Sweden.
    Berggren, P O
    Llopis, J
    Orrenius, S
    Two separate plasma membrane Ca2+ carriers participate in receptor-mediated Ca2+ influx in rat hepatocytes.1994In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1223, no 2, p. 226-33Article in journal (Refereed)
    Abstract [en]

    The plasma membrane Ca2+ carrier system involved in receptor-mediated Ca2+ entry was studied. Using the Ca2+ readdition protocol, the rate of cytosolic free Ca2+ concentration ([Ca2+]i) increase in vasopressin-pretreated hepatocytes was significantly higher than in thapsigargin- or 2,5-di(tert-butyl)hydroquinone-pretreated cells. The addition of Mn2+ to unstimulated hepatocytes resulted in a biphasic quench of fura-2 fluorescence. After an initial phase that was fast in rate but of short duration, the rate of fura-2 quench by Mn2+ became much slower and lasted until all the cellular fura-2 was quenched. Pretreatment of the cells with vasopressin only accelerated the rate of the latter phase but not of the initial one. In agonist-stimulated cells, acidification of the extracellular medium or the presence of ruthenium red, econazole or SK&F 96365 decreased the rates of both [Ca2+]i increase and Mn2+ entry upon addition of the respective cation. By contrast, neomycin and N-tosyl-L-phenylalanine chloromethyl ketone markedly decreased the rate of [Ca2+]i increase upon Ca2+ readdition but had no effect on vasopressin-stimulated Mn2+ entry. None of the treatments affected the ability of vasopressin and thapsigargin to mobilize the internal Ca2+ store. It is concluded that in hepatocytes the two pathways of receptor-mediated Ca2+ entry control two distinct yet pharmacologically related cation carriers.

  • 19.
    Kononenko, Olga
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bazov, Igor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Watanabe, Hiroyuki
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Gerashchenko, Ganna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Dyachok, Oleg
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Verbeek, Dineke S
    Alkass, Kanar
    Druid, Henrik
    Andersson, Malin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Mulder, Jan
    Svenningsen, Åsa Fex
    Rajkowska, Grazyna
    Stockmeier, Craig A
    Krishtal, Oleg
    Yakovleva, Tatiana
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Opioid precursor protein isoform is targeted to the cell nuclei in the human brain2017In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1861, no 2, p. 246-255Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Neuropeptide precursors are traditionally viewed as proteins giving rise to small neuropeptide molecules. Prodynorphin (PDYN) is the precursor protein to dynorphins, endogenous ligands for the κ-opioid receptor. Alternative mRNA splicing of neuropeptide genes may regulate cell- and tissue-specific neuropeptide expression and produce novel protein isoforms. We here searched for novel PDYN mRNA and their protein product in the human brain.

    METHODS: Novel PDYN transcripts were identified using nested PCR amplification of oligo(dT) selected full-length capped mRNA. Gene expression was analyzed by qRT-PCR, PDYN protein by western blotting and confocal imaging, dynorphin peptides by radioimmunoassay. Neuronal nuclei were isolated using fluorescence-activated nuclei sorting (FANS) from postmortem human striatal tissue. Immunofluorescence staining and confocal microscopy was performed for human caudate nucleus.

    RESULTS: Two novel human PDYN mRNA splicing variants were identified. Expression of one of them was confined to the striatum where its levels constituted up to 30% of total PDYN mRNA. This transcript may be translated into ∆SP-PDYN protein lacking 13 N-terminal amino acids, a fragment of signal peptide (SP). ∆SP-PDYN was not processed to mature dynorphins and surprisingly, was targeted to the cell nuclei in a model cellular system. The endogenous PDYN protein was identified in the cell nuclei in human striatum by western blotting of isolated neuronal nuclei, and by confocal imaging.

    CONCLUSIONS AND GENERAL SIGNIFICANCE: High levels of alternatively spliced ∆SP-PDYN mRNA and nuclear localization of PDYN protein suggests a nuclear function for this isoform of the opioid peptide precursor in human striatum.

  • 20.
    Kruczyk, Marcin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Przanowski, Piotr
    Dabrowski, Michal
    Swiatek-Machado, Karolina
    Mieczkowski, Jakub
    Wallerman, Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ronowicz, Anna
    Piotrowski, Arkadiusz
    Wadelius, Claes
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kaminska, Bozena
    Komorowski, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Integration of genome-wide of Stat3 binding and epigenetic modification mapping with transcriptome reveals novel Stat3 target genes in glioma cells2014In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1839, no 11, p. 1341-1350Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in many human tumors, including gliomas, and regulates the expression of genes implicated in proliferation, survival, apoptosis, angiogenesis and immune regulation. Only a small fraction of those genes has been proven to be direct STAT3 targets. In gliomas, STAT3 can play tumor suppressive or oncogenic roles depending on the tumor genetic background with target genes being largely unknown.

    RESULTS: We used chromatin immunoprecipitation, promoter microarrays and deep sequencing to assess the genome-wide occupancy of phospho (p)-Stat3 and epigenetic modifications of H3K4me3 and H3ac in C6 glioma cells. This combined assessment identified a list of 1200 genes whose promoters have both Stat3 binding sites and epigenetic marks characteristic for actively transcribed genes. The Stat3 and histone markings data were also intersected with a set of microarray data from C6 glioma cells after inhibition of Jak2/Stat3 signaling. Subsequently, we found 284 genes characterized by p-Stat3 occupancy, activating histone marks and transcriptional changes. Novel genes were screened for their potential involvement in oncogenesis, and the most interesting hits were verified by ChIP-PCR and STAT3 knockdown in human glioma cells.

    CONCLUSIONS: Non-random association between silent genes, histone marks and p-Stat3 binding near transcription start sites was observed, consistent with its repressive role in transcriptional regulation of target genes in glioma cells with specific genetic background.

  • 21. Kuilenburg, André B P van
    et al.
    Meijer, Judith
    Tanck, Michael W T
    Dobritzsch, Doreen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Zoetekouw, Lida
    Dekkers, Lois-Lee
    Roelofsen, Jeroen
    Meinsma, Rutger
    Wymenga, Machteld
    Kulik, Wim
    Büchel, Barbara
    Hennekam, Raoul C M
    Largiadèr, Carlo R
    Phenotypic and clinical implications of variants in the dihydropyrimidine dehydrogenase gene.2016In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1862, no 4, p. 754-762Article in journal (Refereed)
    Abstract [en]

    Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of the pyrimidine bases uracil, thymine and the antineoplastic agent 5-fluorouracil. Genetic variations in the gene encoding DPD (DPYD) have emerged as predictive risk alleles for 5FU-associated toxicity. Here we report an in-depth analysis of genetic variants in DPYD and their consequences for DPD activity and pyrimidine metabolites in 100 Dutch healthy volunteers. 34 SNPs were detected in DPYD and 15 SNPs were associated with altered plasma concentrations of pyrimidine metabolites. DPD activity was significantly associated with the plasma concentrations of uracil, the presence of a specific DPYD mutation (c.1905+1G>A) and the combined presence of three risk variants in DPYD (c.1905+1G>A, c.1129-5923C>G, c.2846A>T), but not with an altered uracil/dihydrouracil (U/UH2) ratio. Various haplotypes were associated with different DPD activities (haplotype D3, a decreased DPD activity; haplotype F2, an increased DPD activity). Functional analysis of eight recombinant mutant DPD enzymes showed a reduced DPD activity, ranging from 35% to 84% of the wild-type enzyme. Analysis of a DPD homology model indicated that the structural effect of the novel p.G401R mutation is most likely minor. The clinical relevance of the p.D949V mutation was demonstrated in a cancer patient heterozygous for the c.2846A>T mutation and a novel nonsense mutation c.1681C>T (p.R561X), experiencing severe grade IV toxicity. Our studies showed that the endogenous levels of uracil and the U/UH2 ratio are poor predictors of an impaired DPD activity. Loading studies with uracil to identify patients with a DPD deficiency warrants further investigation.

  • 22. Lohkamp, Bernhard
    et al.
    Voevodskaya, Nina
    Lindqvist, Ylva
    Dobritzsch, Doreen
    Karolinska Institutet.
    Insights into the mechanism of dihydropyrimidine dehydrogenase from site-directed mutagenesis targeting the active site loop and redox cofactor coordination2010In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1804, no 12, p. 2198-2206Article in journal (Refereed)
    Abstract [en]

    In mammals, the pyrimidines uracil and thymine are metabolised by a three-step reductive degradation pathway. Dihydropyrimidine dehydrogenase (DPD) catalyses its first and rate-limiting step, reducing uracil and thymine to the corresponding 5,6-dihydropyrimidines in an NADPH-dependent reaction. The enzyme is an adjunct target in cancer therapy since it rapidly breaks down the anti-cancer drug 5-fluorouracil and related compounds. Five residues located in functionally important regions were targeted in mutational studies to investigate their role in the catalytic mechanism of dihydropyrimidine dehydrogenase from pig. Pyrimidine binding to this enzyme is accompanied by active site loop closure that positions a catalytically crucial cysteine (C671) residue. Kinetic characterization of corresponding enzyme mutants revealed that the deprotonation of the loop residue H673 is required for active site closure, while S670 is important for substrate recognition. Investigations on selected residues involved in binding of the redox cofactors revealed that the first FeS cluster, with unusual coordination, cannot be reduced and displays no activity when Q156 is mutated to glutamate, and that R235 is crucial for FAD binding.

  • 23.
    Mahammad, Saleemulla
    et al.
    Stockholms universitet, Wenner-Grens institut.
    Parmryd, Ingela
    Stockholms universitet, Wenner-Grens institut.
    Cholesterol homeostasis in T cells. Methyl-beta-cyclodextrin treatment results in equal loss of cholesterol from Triton X-100 soluble and insoluble fractions.2008In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1778, no 5, p. 1251-8Article in journal (Refereed)
    Abstract [en]

    Methyl-beta-cycloclextrin (MBCD) is frequently used to acutely deplete cells of cholesterol. A widespread assumption is that MBCD preferentially targets cholesterol in lipid rafts and that sensitivity to MBCD is proof of lipid raft involvement in a cellular process. To analyse any MBCD preference systematically, progressive cholesterol depletion of Jurkat T cells was performed using MBCD and [H-3]-cholesterol. It was found that at 37 degrees C, MBCD extracts similar proportions of cholesterol from the Triton X-100 resistant (lipid raft enriched) as it does from other cellular fractions and that the cells rapidly reestablish the relative differences in cholesterol concentration between different compartments. Moreover, cells restore the cholesterol level in the plasma membrane by mobilising cholesterol from intracellular cholesterol stores. Interestingly, mere incubation at 0 degrees C caused a loss of plasma membrane cholesterol with a concomitant increase in cholesteryl esters and adiposomes. Moreover, only 35% of total cholesterol could be extracted by MBCD at 0 degrees C and was accompanied by a complete loss of plasma membrane and endocytotic recycling centre filipin staining. This study clearly shows that MBCD does not specifically extract cholesterol from any cellular fraction, that cholesterol redistributes upon temperature changes and that intracellular cholesterol stores can be used to replenish plasma membrane cholesterol.

  • 24.
    Méndez-López, Lucía
    et al.
    Departamento de Bioquímica e Bioloxía Molecular, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain.
    Hellman, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Ibarguren, Izaskun
    Departamento de Bioquímica e Bioloxía Molecular, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain.
    Villamarín, J Antonio
    Departamento de Bioquímica e Bioloxía Molecular, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain.
    Filamin isoforms in molluscan smooth muscle2012In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1824, no 12, p. 1334-1341Article in journal (Refereed)
    Abstract [en]

    The role of filamin in molluscan catch muscles is unknown. In this work three proteins isolated from the posterior adductor muscle of the sea mussel Mytilus galloprovincialis were identified by MALDI-TOF/TOF MS as homologous to mammalian filamin. They were named FLN-270, FLN-230 and FLN-105, according to their apparent molecular weight determined by SDS-PAGE: 270kDa, 230kDa and 105kDa, respectively. Both FLN-270 and FLN-230 contain the C-terminal dimerization domain and the N-terminal actin-binding domain typical of filamins. These findings, together with the data from peptide mass fingerprints, indicate that FLN-270 and FLN-230 are different isoforms of mussel filamin, with FLN-230 being the predominant isoform in the mussel catch muscle. De novo sequencing data revealed structural differences between both filamin isoforms at the rod 2 segment, the one responsible for the interaction of filamin with the most of its binding partners. FLN270 but not FLN230 was phosphorylated in vitro by cAMP-dependent protein kinase. As for the FLN-105, it would be an N-terminal proteolytic fragment generated from the FLN-270 isoform or a C-terminally truncated variant of filamin. On the other hand, a 45-kDa protein that copurifies with mussel catch muscle filamins was identified as the mussel calponin-like protein. The fact that this protein coelutes with the FLN-270 isoform from a gel filtration chromatography suggests a specific interaction between both proteins.

  • 25. Neuzil, Jiri
    et al.
    Danielson, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
    Welch, G Rickey
    Ovádi, Judit
    Cooperative effect of fructose bisphosphate and glyceraldehyde-3-phosphate dehydrogenase on aldolase action1990In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1037, no 3, p. 307-312Article in journal (Refereed)
    Abstract [en]

    The combination of binding and kinetic approaches is suggested to study (i) the mechanism of substrate-modulated dynamic enzyme associations; (ii) the specificity of enzyme interactions. The effect of complex formation between aldolase and glyceraldehyde-3-phosphate dehydrogenase (d-glyceraldehyde-3-phosphate:NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12) on aldolase catalysis was investigated under pseudo-first-order conditions. No change in kcat but a significant increase in KM of fructose 1,6-bisphosphate for aldolase was found when both enzymes were obtained from muscle. In contrast, kcat rather than KM changed if dehydrogenase was isolated from yeast. Next, the conversion of fructose 1-phosphate was not affected by interactions between enzyme couples isolated from muscle. The influence of fructose phosphates on the enzyme-complex formation was studied by means of covalently attached fluorescent probe. We found that the interaction was not perturbed by the presence of fructose 1-phosphate; however, fructose 1,6-bisphosphate altered the dissociation constant of the enzyme complex. A molecular model for fructose 1,6-bisphosphate-modulated enzyme interaction has been evaluated which suggests that high levels of fructose bisphosphate would drive the formation of the ‘channelling’ complex between aldolase and glyceraldehyde-3-phosphate dehydrogenase.

  • 26. Nore, Beston F
    et al.
    Mattsson, Pekka T
    Antonsson, Per
    Bäckesjö, Carl-Magnus
    Westlund, Anna
    Lennartsson, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Hansson, Henrik
    Löw, Peter
    Rönnstrand, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Smith, C I Edvard
    Identification of phosphorylation sites within the SH3 domains of Tec family tyrosine kinases2003In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1645, no 2, p. 123-132Article in journal (Refereed)
    Abstract [en]

    Tec family protein tyrosine kinases (TFKs) play a central role in hematopoietic cellular signaling. Initial activation takes place through specific tyrosine phosphorylation situated in the activation loop. Further activation occurs within the SH3 domain via a transphosphorylation mechanism, which for Bruton's tyrosine kinase (Btk) affects tyrosine 223. We found that TFKs phosphorylate preferentially their own SH3 domains, but differentially phosphorylate other member family SH3 domains, whereas non-related SH3 domains are not phosphorylated. We demonstrate that SH3 domains are good and reliable substrates. We observe that transphosphorylation is selective not only for SH3 domains, but also for dual SH3SH2 domains. However, the dual domain is phosphorylated more effectively. The major phosphorylation sites were identified as conserved tyrosines, for Itk Y180 and for Bmx Y215, both sites being homologous to the Y223 site in Btk. There is, however, one exception because the Tec-SH3 domain is phosphorylated at a non-homologous site, nevertheless a conserved tyrosine, Y206. Consistent with these findings, the 3D structures for SH3 domains point out that these phosphorylated tyrosines are located on the ligand-binding surface. Because a number of Tec family kinases are coexpressed in cells, it is possible that they could regulate the activity of each other through transphosphorylation.

  • 27. Palmieri-Thiers, Cynthia
    et al.
    Canaan, Stéphane
    Brunini, Virginie
    Lorenzi, Vannina
    Tomi, Félix
    Desseyn, Jean-Luc
    Garscha, Ulrike
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Oliw, Ernst H
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Berti, Liliane
    Maury, Jacques
    A lipoxygenase with dual positional specificity is expressed in olives (Olea europaea L.) during ripening2009In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1791, no 5, p. 339-346Article in journal (Refereed)
    Abstract [en]

    Plant lipoxygenases (LOXs) are a class of widespread dioxygenases catalysing the hydroperoxidation of polyunsaturated fatty acids. Although multiple isoforms of LOX have been detected in a wide range of plants, their physiological roles remain to be clarified. With the aim to clarify the occurrence of LOXs in olives and their contribution to the elaboration of the olive oil aroma, we cloned and characterized the first cDNA of the LOX isoform which is expressed during olive development. The open reading frame encodes a polypeptide of 864 amino acids. This olive LOX is a type-1 LOX which shows a high degree of identity at the peptide level towards hazelnut (77.3%), tobacco (76.3%) and almond (75.5%) LOXs. The recombinant enzyme shows a dual positional specificity, as it forms both 9- and 13-hydroperoxide of linoleic acid in a 2:1 ratio, and would be defined as 9/13-LOX. Although a LOX activity was detected throughout the olive development, the 9/13-LOX is mainly expressed at late developmental stages. Our data suggest that there are at least two Lox genes expressed in black olives, and that the 9/13-LOX is associated with the ripening and senescence processes. However, due to its dual positional specificity and its expression pattern, its contribution to the elaboration of the olive oil aroma might be considered.

  • 28.
    Pardali, Katerina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Moustakas, Aristidis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm , Ludwig Institute for Cancer Research.
    Actions of TGF-beta as tumor suppressor and pro-metastatic factor in human cancer2007In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1775, no 1, p. 21-62Article, review/survey (Refereed)
    Abstract [en]

    Transforming growth factor-beta (TGF-beta) is a secreted polypeptide that signals via receptor serine/threonine kinases and intracellular Smad effectors. TGF-beta inhibits proliferation and induces apoptosis in various cell types, and accumulation of loss-of-function mutations in the TGF-beta receptor or Smad genes classify the pathway as a tumor suppressor in humans. In addition, various oncogenic pathways directly inactivate the TGF-beta receptor-Smad pathway, thus favoring tumor growth. On the other hand, all human tumors overproduce TGF-beta whose autocrine and paracrine actions promote tumor cell invasiveness and metastasis. Accordingly, TGF-beta induces epithelial-mesenchymal transition, a differentiation switch that is required for transitory invasiveness of carcinoma cells. Tumor-derived TGF-beta acting on stromal fibroblasts remodels the tumor matrix and induces expression of mitogenic signals towards the carcinoma cells, and upon acting on endothelial cells and pericytes, TGF-beta regulates angiogenesis. Finally, TGF-beta suppresses proliferation and differentiation of lymphocytes including cytolytic T cells, natural killer cells and macrophages, thus preventing immune surveillance of the developing tumor. Current clinical approaches aim at establishing novel cancer drugs whose mechanisms target the TGF-beta pathway. In conclusion, TGF-beta signaling is intimately implicated in tumor development and contributes to all cardinal features of tumor cell biology.

  • 29. Pasupuleti, Mukesh
    et al.
    Chalupka, Anna
    Mörgelin, Matthias
    Schmidtchen, Artur
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Tryptophan end-tagging of antimicrobial peptides for increased potency against Pseudomonas aeruginosa2009In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1790, no 8, p. 800-808Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Due to increasing antibiotics resistance, antimicrobial peptides (AMPs) are receiving increased attention. Pseudomonas aeruginosa is a major pathogen in this context, involved, e.g., in keratitis and wound infections. Novel bactericidal agents against this pathogen are therefore needed. METHODS: Bactericidal potency was monitored by radial diffusion, viable count, and minimal inhibitory concentration assays, while toxicity was probed by hemolysis. Mechanistic information was obtained from assays on peptide-induced vesicle disruption and lipopolysaccharide binding. RESULTS: End-tagging by hydrophobic amino acids yields increased potency of AMPs against P. aeruginosa, irrespective of bacterial proteinase production. Exemplifying this by two peptides from kininogen, GKHKNKGKKNGKHNGWK and KNKGKKNGKH, potency increased with tag length, correlating to more efficient bacterial wall and vesicle rupture, and to more pronounced P. aeruginosa lipopolysaccharide binding. End-tag effects remained at high electrolyte concentration and in the presence of plasma or anionic macromolecular scavengers. The tagged peptides displayed stability against P. aeruginosa elastase, and were potent ex vivo, both in a contact lens model and in a skin wound model. GENERAL SIGNIFICANCE: End-tagging, without need for post-peptide synthesis modification, may be employed to enhance AMP potency against P. aeruginosa at maintained limited toxicity.

  • 30.
    Pavez Loriè, Elizabeth
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Dermatology and Venereology.
    Li, Hao
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Dermatology and Venereology.
    Vahlquist, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Dermatology and Venereology.
    Törmä, Hans
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Dermatology and Venereology.
    The involvement of cytochrome p450 (CYP) 26 in the retinoic acid metabolism of human epidermal keratinocytes2009In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1791, no 3, p. 220-228Article in journal (Refereed)
    Abstract [en]

    All-trans retinoic acid (RA) levels are controlled by enzymes of the vitamin A metabolism (RDH16, RalDH2, and LRAT) and RA catabolism (CYP26 and CYP2S1). Here, the mRNA expression of these enzymes was investigated in human keratinocytes at different Ca(2+)concentrations and after exposure to RA and CYP26 inhibitors. Cellular differentiation (high Ca(2+)) increased the expression of LRAT, RDH16 and RalDH2, and decreased CYP26B1. RA (1 microM) induced CYP26A1, CYP26B1, CYP2S1, CRABPII and LRAT mRNA. The CYP26 inhibitor talarozole altered CYP26A1 and LRAT mRNA expression in a similar way as RA, increased the cellular accumulation of [(3)H]RA, and induced a punctate CRABPII staining, also observed after siRNA knock-down of CYP26B1 (but not after RA exposure). Furthermore, CYP26B1 siRNA increased the accumulation of [(3)H]RA and the CRABPII mRNA, suggesting an augmented retinoid signalling. Thus CYP26B1 appears essential for RA catabolism under physiological conditions, whereas CYP26A1 might play a greater role during RA excess.

  • 31.
    Poliakov, Anton
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Johansson, Anja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Åkerblom, Eva
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Oscarsson, Karin
    Samuelsson, Bertil
    Hallberg, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Danielson, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Structure-activity relationships for the selectivity of hepatitis C virus NS3 protease inhibitors2004In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1672, no 1, p. 51-59Article in journal (Refereed)
    Abstract [en]

    The selectivity of hepatitis C virus (HCV) non-structural protein 3 (NS3) protease inhibitors was determined by evaluating their inhibitory effect on other serine proteases (human leukocyte elastase (HLE), porcine pancreatic elastase (PPE), bovine pancreatic chymotrypsin (BPC)) and a cysteine protease (cathepsin B). For these peptide inhibitors, the P1-side chain and the C-terminal group were the major determinants of selectivity. Inhibitors with electrophilic C-terminal residues were generally non-selective while compounds with non-electrophilic C-terminal residues were more selective. Furthermore, compounds with P1 aminobutyric acid residues were non-selective, while 1-aminocyclopropane-1-carboxylic acid (ACPC) and norvaline-based inhibitors were generally selective. The most potent and selective inhibitors of NS3 protease tested contained a non-electrophilic phenyl acyl sulfonamide C-terminal residue. HLE was most likely to be inhibited by the HCV protease inhibitors, in agreement with similar substrate specificities for these enzymes. The identified structure-activity relationships for selectivity are of significance for design of selective HCV NS3 protease inhibitors.

  • 32.
    Sancho, Patricia
    et al.
    L'Hospitalet, Barcelona, Spain.
    Bertran, Esther
    L'Hospitalet, Barcelona, Spain.
    Caja, Laia
    L'Hospitalet, Barcelona, Spain.
    Carmona-Cuenca, Irene
    Universidad Complutense, Madrid, Spain.
    Murillo, Miguel M
    Universidad Complutense, Madrid, Spain.
    Fabregat, Isabel
    L'Hospitalet, Barcelona, Spain.
    The inhibition of the epidermal growth factor (EGF) pathway enhances TGF-beta-induced apoptosis in rat hepatoma cells through inducing oxidative stress coincident with a change in the expression pattern of the NADPH oxidases (NOX) isoforms.2009In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1793, no 2, p. 253-263Article in journal (Refereed)
    Abstract [en]

    Transforming growth factor-beta (TGF-beta) induces apoptosis in hepatocytes, through a mechanism mediated by reactive oxygen species (ROS) production. Numerous tumoral cells develop mechanisms to escape from the TGF-beta-induced tumor suppressor effects. In this work we show that in FaO rat hepatoma cells inhibition of the epidermal growth factor receptor (EGFR) with the tyrphostin AG1478 enhances TGF-beta-induced cell death, coincident with an elevated increase in ROS production and GSH depletion. These events correlate with down-regulation of genes involved in the maintenance of redox homeostasis, such as gamma-GCS and MnSOD, and elevated mitochondrial ROS. Nonetheless, not all the ROS proceed from the mitochondria. Emerging evidences indicate that ROS production by TGF-beta is also mediated by the NADPH oxidase (NOX) system. TGF-beta-treated FaO cells induce nox1 expression. However, the treatment with TGF-beta and AG1478 greatly enhanced the expression of another family member: nox4. NOX1 and NOX4 targeted knock-down by siRNA experiments suggest that they play opposite roles, because NOX1 knockdown increases caspase-3 activity and cell death, whilst NOX4 knock-down attenuates the apoptotic process. This attenuation correlates with maintenance of GSH and antioxidant enzymes levels. In summary, EGFR inhibition enhances apoptosis induced by TGF-beta in FaO rat hepatoma cells through an increased oxidative stress coincident with a change in the expression pattern of NOX enzymes.

  • 33. Schnackerz, Klaus D
    et al.
    Dobritzsch, Doreen
    Karolinska Institutet.
    Amidohydrolases of the reductive pyrimidine catabolic pathway: purification, characterization, structure, reaction mechanisms and enzyme deficiency2008In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1784, no 3, p. 431-444Article, review/survey (Refereed)
    Abstract [en]

    In the reductive pyrimidine catabolic pathway uracil and thymine are converted to beta-alanine and beta-aminoisobutyrate. The amidohydrolases of this pathway are responsible for both the ring opening of dihydrouracil and dihydrothymine (dihydropyrimidine amidohydrolase) and the hydrolysis of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyrate (beta-alanine synthase). The review summarizes what is known about the properties, kinetic parameters, three-dimensional structures and reaction mechanisms of these proteins. The two amidohydrolases of the reductive pyrimidine catabolic pathway have unrelated folds, with dihydropyrimidine amidohydrolase belonging to the amidohydrolase superfamily while the beta-alanine synthase from higher eukaryotes belongs to the nitrilase superfamily. beta-Alanine synthase from Saccharomyces kluyveri is an exception to the rule and belongs to the Acyl/M20 family.

  • 34. Schnackerz, Klaus D
    et al.
    Dobritzsch, Doreen
    Karolinska Institutet.
    Lindqvist, Ylva
    Cook, Paul F
    Dihydropyrimidine dehydrogenase: a flavoprotein with four iron-sulfur clusters2004In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1701, no 1-2, p. 61-74Article in journal (Refereed)
    Abstract [en]

    Dihydropyrimidine dehydrogenase (DPD) is the first and rate-limiting enzyme in the pathway for degradation of pyrimidines, responsible for the reduction of the 5,6-double bond to give the dihydropyrimidine using NADPH as the reductant. The enzyme is a dimer of 220 kDa, and each monomer contains one FAD, one FMN, and four FeS clusters. The FAD is situated at one end of the protein, the FMN is at the other, and four FeS clusters form a conduit for electron transfer between the two sites comprised of two FeS clusters from each monomer. The enzyme has a two-site ping-pong mechanism with NADPH reducing FAD and reduced FMN responsible for reducing the pyrimidine. Solvent deuterium kinetic isotope effects indicate a rate-limiting reduction of FAD accompanied by pH-dependent structural rearrangement for proper orientation of the nicotinamide ring. Transfer of electrons from site 1 to site 2 is downhill with FMN rapidly reduced by FADH(2) via the FeS conduit. The reduction of the pyrimidine at site 2 proceeds using general acid catalysis with protonation at N5 of FMN carried out by K574 as FMN is reduced and protonation at C5 of the pyrimidine by C671 as it is reduced. Kinetic isotope effects indicate a stepwise reaction for reduction of the pyrimidine with hydride transfer at C6 preceding proton transfer at C5, with a late transition state for the proton transfer step.

  • 35.
    Sooman, Linda
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Wennman, Anneli
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Hamberg, Mats
    Hoffmann, Inga
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Oliw, Ernst H
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Replacement of two amino acids of 9R-dioxygenase-allene oxide synthase of Aspergillus niger inverts the chirality of the hydroperoxide and the allene oxide2016In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1861, no 2, p. 108-118Article in journal (Refereed)
    Abstract [en]

    The genome of Aspergillus niger codes for a fusion protein (EHA25900), which can be aligned with ~50% sequence identity to 9S-dioxygenase (DOX)-allene oxide synthase (AOS) of Fusarium oxysporum, homologues of the Fusarium and Colletotrichum complexes and with over 62% sequence identity to homologues of Aspergilli, including (DOX)-9R-AOS of Aspergillus terreus. The aims were to characterize the enzymatic activities of EHA25900 and to identify crucial amino acids for the stereospecificity. Recombinant EHA25900 oxidized 18:2n-6 sequentially to 9R-hydroperoxy-10(E),12(Z)-octadecadienoic acid (9R-HPODE) and to a 9R(10)-allene oxide. 9S- and 9R-DOX-AOS catalyze abstraction of the pro-R hydrogen at C-11, but the direction of oxygen insertion differs. A comparison between twelve 9-DOX domains of 9S- and 9R-DOX-AOS revealed conserved amino acid differences, which could contribute to the chirality of products. The Gly616Ile replacement of 9R-DOX-AOS (A. niger) increased the biosynthesis of 9S-HPODE and the 9S(10)-allene oxide, whereas the Phe627Leu replacement led to biosynthesis of 9S-HPODE and the 9S(10)-allene oxide as main products. The double mutant (Gly616Ile, Phe627Leu) formed over 90% of the 9S stereoisomer of HPODE. 9S-HPODE was formed by antarafacial hydrogen abstraction and oxygen insertion, i.e., the original H-abstraction was retained but the product chirality was altered. We conclude that 9R-DOX-AOS can be altered to 9S-DOX-AOS by replacement of two amino acids (Gly616Ile, Phe627Leu) in the DOX domain.

  • 36.
    Strömstedt, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Kristiansen, Per Eugen
    Univ Oslo, Dept Mol Biosci, Box 1041, N-0316 Oslo, Norway.
    Gunasekera, Sunithi
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Grob, Nathalie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Skjeldal, Lars
    Norwegian Univ Life Sci, Dept Chem Biochem & Food Sci, N-1432 As, Norway.
    Göransson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Selective membrane disruption by the cyclotide kalata B7: complex ions and essential functional groups in the phosphatidylethanolamine binding pocket2016In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1858, no 6, p. 1317-1327Article in journal (Refereed)
    Abstract [en]

    The cyclic cystine knot plant peptides called cyclotides are active against a wide variety of organisms. This is primarily achieved through membrane binding and disruption, in part deriving from a high affinity for phosphatidylethanolamine (PE) lipids. Some cyclotides, such as kalata B7 (kB7), form complexes with divalent cations in a pocket associated with the tyrosine residue at position 15 (Tyr15). In the current work we explore the effect of cations on membrane leakage caused by cyclotides kB1, kB2 and kB7, and we identify a functional group that is essential for PE selectivity. The presence of PE-lipids in liposomes increased the membrane permeabilizing potency of the cyclotides, with the potency of kB7 increasing by as much as 740-fold. The divalent cations Mn(2+), Mg(2+) and Ca(2+) had no apparent effect on PE selectivity. However, amino acid substitutions in kB7 proved that Tyr15 is crucial for PE-selective membrane permeabilization on various liposome systems. Although the tertiary structure of kB7 was maintained, as reflected by the NMR solution structure, mutating Tyr into Ser at position 15 resulted in substantially reduced PE selectivity. Ala substitution at the same position produced a similar reduction in PE selectivity, while substitution with Phe maintained high selectivity. We conclude that the phenyl ring in Tyr15 is critical for the high PE selectivity of kB7. Our results suggest that PE-binding and divalent cation coordination occur in the same pocket without adverse effects of competitive binding for the phospholipid.

  • 37.
    Tolmachev, Vladimir
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences.
    Stone-Elander, Sharon
    Radiolabelled proteins for positron emission tomography: pros and cons of labelling methods2010In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1800, no 5, p. 487-510Article, review/survey (Refereed)
    Abstract [en]

    BACKGROUND: Dynamic biomedical research is currently yielding a wealth of information about disease-associated molecular alterations on cell surfaces and in the extracellular space. The ability to visualize and quantify these alterations in vivo could provide important diagnostic information and be used to guide individually-optimized therapy. Biotechnology can provide proteinaceous molecular probes with highly specific target recognitions. Suitably labelled, these may be used as tracers for radionuclide-based imaging of molecular disease signatures. If the labels are positron-emitting radionuclides, the superior resolution, sensitivity and quantification capability of positron emission tomography (PET) can be exploited.

    SCOPE OF REVIEW: This article discusses different approaches to labelling proteins with positron-emitting nuclides with suggestions made depending on the biological features of the tracers.

    MAJOR CONCLUSIONS: Factors such as matching biological and physical half-lives, availability of the nuclide, labelling yields, and influences of labelling on targeting properties (affinity, charge and lipophilicity, cellular processing and retention of catabolites) should be considered when selecting a labelling strategy for each proteinaceous tracer.

    GENERAL SIGNIFICANCE: The labelling strategy used can make all the difference between success and failure in a tracer application. This review emphasises chemical, biological and pharmacological considerations in labelling proteins with positron-emitting radionuclides.

  • 38. van Kuilenburg, André B P
    et al.
    Dobritzsch, Doreen
    Karolinska Institutet.
    Meijer, Judith
    Krumpel, Michael
    Selim, Laila A
    Rashed, Mohamed S
    Assmann, Birgit
    Meinsma, Rutger
    Lohkamp, Bernhard
    Ito, Tetsuya
    Abeling, Nico G G M
    Saito, Kayoko
    Eto, Kaoru
    Smitka, Martin
    Engvall, Martin
    Zhang, Chunhua
    Xu, Wang
    Zoetekouw, Lida
    Hennekam, Raoul C M
    ß-ureidopropionase deficiency: phenotype, genotype and protein structural consequences in 16 patients2012In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1822, no 7, p. 1096-108Article in journal (Refereed)
    Abstract [en]

    ß-ureidopropionase is the third enzyme of the pyrimidine degradation pathway and catalyzes the conversion of N-carbamyl-ß-alanine and N-carbamyl-ß-aminoisobutyric acid to ß-alanine and ß-aminoisobutyric acid, ammonia and CO(2). To date, only five genetically confirmed patients with a complete ß-ureidopropionase deficiency have been reported. Here, we report on the clinical, biochemical and molecular findings of 11 newly identified ß-ureidopropionase deficient patients as well as the analysis of the mutations in a three-dimensional framework. Patients presented mainly with neurological abnormalities (intellectual disabilities, seizures, abnormal tonus regulation, microcephaly, and malformations on neuro-imaging) and markedly elevated levels of N-carbamyl-ß-alanine and N-carbamyl-ß-aminoisobutyric acid in urine and plasma. Analysis of UPB1, encoding ß-ureidopropionase, showed 6 novel missense mutations and one novel splice-site mutation. Heterologous expression of the 6 mutant enzymes in Escherichia coli showed that all mutations yielded mutant ß-ureidopropionase proteins with significantly decreased activity. Analysis of a homology model of human ß-ureidopropionase generated using the crystal structure of the enzyme from Drosophila melanogaster indicated that the point mutations p.G235R, p.R236W and p.S264R lead to amino acid exchanges in the active site and therefore affect substrate binding and catalysis. The mutations L13S, R326Q and T359M resulted most likely in folding defects and oligomer assembly impairment. Two mutations were identified in several unrelated ß-ureidopropionase patients, indicating that ß-ureidopropionase deficiency may be more common than anticipated.

  • 39. van Kuilenburg, André B P
    et al.
    Meijer, Judith
    Maurer, Dirk
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Dobritzsch, Doreen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Meinsma, Rutger
    Los, Maartje
    Knegt, Lia C
    Zoetekouw, Lida
    Jansen, Rob L H
    Dezentjé, Vincent
    van Huis-Tanja, Lieke H
    van Kampen, Roel J W
    Hertz, Jens Michael
    Hennekam, Raoul C M
    Severe fluoropyrimidine toxicity due to novel and rare DPYD missense mutations, deletion and genomic amplification affecting DPD activity and mRNA splicing2017In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1863, no 3, p. 721-730Article in journal (Refereed)
    Abstract [en]

    Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5FU). Genetic variations in DPD have emerged as predictive risk factors for severe fluoropyrimidine toxicity. Here, we report novel and rare genetic variants underlying DPD deficiency in 9 cancer patients presenting with severe fluoropyrimidine-associated toxicity. All patients possessed a strongly reduced DPD activity, ranging from 9 to 53% of controls. Analysis of the DPD gene (DPYD) showed the presence of 21 variable sites including 4 novel and 4 very rare aberrations: 3 missense mutations, 2 splice-site mutations, 1 intronic mutation, a deletion of 21 nucleotides and a genomic amplification of exons 9-12. Two novel/rare variants (c.2843T>C, c.321+1G>A) were present in multiple, unrelated patients. Functional analysis of recombinantly-expressed DPD mutants carrying the p.I948T and p.G284V mutation showed residual DPD activities of 30% and 0.5%, respectively. Analysis of a DPD homology model indicated that the p.I948T and p.G284V mutations may affect electron transfer and the binding of FAD, respectively. cDNA analysis showed that the c.321+1G>A mutation in DPYD leads to skipping of exon 4 immediately upstream of the mutated splice-donor site in the process of DPD pre-mRNA splicing. A lethal toxicity in two DPD patients suggests that fluoropyrimidines combined with other therapies such as radiotherapy might be particularly toxic for DPD deficient patients. Our study advocates a more comprehensive genotyping approach combined with phenotyping strategies for upfront screening for DPD deficiency to ensure the safe administration of fluoropyrimidines.

  • 40.
    Wang, Shu
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Internal Medicine.
    Zhou, Yinghua
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Internal Medicine.
    Lukinius, Agneta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Pathology.
    Öberg, Kjell
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Internal Medicine.
    Skogseid, Britt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Internal Medicine.
    Gobl, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Internal Medicine.
    Molecular cloning and characterization of a cDNA encoding mouse phospholipase C-β31998In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1393, no 1, p. 173-178Article in journal (Other academic)
    Abstract [en]

    A cDNA encoding mouse PLC-beta3 (mPLC-beta3) was identified by screening a mouse kidney cDNA library and using the rapid amplification of cDNA ends (RACE) method. The predicted open reading frame was 3705 bp in length. The deduced 1235 amino acid (aa) sequence shares 95.3% and 92% homology with the sequences of rat and human PLC-beta3, respectively. The corresponding mRNA is highly expressed in kidney, skeletal muscle, liver, lung, heart and brain. In spleen, mPLC-beta3 mRNA was not detectable, which is in contrast to humans where there is a distinct expression. Using ultrastructural immunocytochemistry, mPLC-beta3 expression was detected in the heterochromatin of the nucleus in mouse brain neurons. The observation of PLC-beta3 nuclear localization suggests that PLC-beta3 may have intranuclear functions.

  • 41.
    Widersten, Mikael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Gurell, Ann
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Lindberg, Diana
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Structure-function relationships of epoxide hydrolases and their potential use in biocatalysis2010In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1800, no 3, p. 316-326Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Chiral epoxides and diols are important synthons for manufacturing fine chemicals and pharmaceuticals. The epoxide hydrolases (EC 3.3.2.-) catalyze the hydrolytic ring opening of epoxides producing the corresponding vicinal diol. Several isoenzymes display catalytic properties that position them as promising biocatalytic tools for the generation of enantiopure epoxides and diols. SCOPE OF REVIEW: This review focuses on the present data on enzyme structure and function in connection to biocatalytic applications. Available data on biocatalysis employed for purposes of stereospecific ring opening, to produce chiral vicinal diols, and kinetic resolution regimes, to achieve enantiopure epoxides, are discussed and related to results gained from structure-activity studies on the enzyme catalysts. More recent examples of the concept of directed evolution of enzyme function are also presented. MAJOR CONCLUSIONS: The present understanding of structure-activity relationships in epoxide hydrolases regarding chemical catalysis is strong. With the ongoing research, a more detailed view of the factors that influence substrate specificities and stereospecificities is expected to arise. The already present use of epoxide hydrolases in synthetic applications is expected to expand as new enzymes are being isolated and characterized. Refined methodologies for directed evolution of desired catalytic and physicochemical properties may further boost the development of novel and useful biocatalysts. GENERAL SIGNIFICANCE: The catalytic power of enzymes provides new possibilities for efficient, specific and sustainable technologies to be developed for production of useful chemicals.

  • 42. Yu, Z W
    et al.
    Burén, J
    Enerbäck, S
    Nilsson, E
    Samuelsson, L
    Eriksson, Jan W
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Endocrinology, Diabetes and Metabolism.
    Insulin can enhance GLUT4 gene expression in 3T3-F442A cells and this effect is mimicked by vanadate but counteracted by cAMP and high glucose--potential implications for insulin resistance.2001In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1535, no 2, p. 174-85Article in journal (Refereed)
    Abstract [en]

    It is well-established that high levels of cAMP or glucose can produce insulin resistance. The aim of this study was to characterize the interaction between these agents and insulin with respect to adipose tissue/muscle glucose transporter isoform (glucose transporter 4, GLUT4) gene regulation in cultured 3T3-F442A adipocytes and to further elucidate the GLUT4-related mechanisms in insulin resistance. Insulin (10(4) microU/ml) treatment for 16 h clearly increased GLUT4 mRNA level in cells cultured in medium containing 5.6 mM glucose but not in cells cultured in medium with high glucose (25 mM). 8-Bromo-cAMP (1 or 4 mM) or N(6)-monobutyryl cAMP, a hydrolyzable and a non-hydrolyzable cAMP analog, respectively, markedly decreased the GLUT4 mRNA level irrespective of glucose concentrations. In addition, these cAMP analogs also inhibited the upregulating effect of insulin on GLUT4 mRNA level. Interestingly, the tyrosine phosphatase inhibitor vanadate (1-50 microM) clearly increased GLUT4 mRNA level in a time- and concentration-dependent manner. Furthermore, cAMP-induced inhibition of the insulin effect was also prevented by vanadate. In parallel to the effects on GLUT4 gene expression, both insulin, vanadate and cAMP produced similar changes in cellular GLUT4 protein content and cAMP impaired the effect of insulin to stimulate (14)C-deoxyglucose uptake. In contrast, insulin, vanadate or cAMP did not alter insulin receptor (IR) mRNA or the cellular content of IR protein. In conclusion: (1) Both insulin and vanadate elicit a stimulating effect on GLUT4 gene expression in 3T3-F442A cells, but a prerequisite is that the surrounding glucose concentration is low. (2) Cyclic AMP impairs the insulin effect on GLUT4 gene expression, but this is prevented by vanadate, probably by enhancing the tyrosine phosphorylation of signalling peptides and/or transcription factors. (3) IR gene and protein expression is not altered by insulin, vanadate or cAMP in this cell type. (4) The changes in GLUT4 gene expression produced by cAMP or vanadate are accompanied by similar alterations in GLUT4 protein expression and glucose uptake, suggesting a role of GLUT4 gene expression for the long-term regulation of cellular insulin action on glucose transport.

  • 43. Yu, Z W
    et al.
    Posner, B I
    Smith, U
    Eriksson, Jan W
    The Lundberg Laboratory for Diabetes Research, Department of Internal Medicine, University of Göteborg, Sahlgrenska University Hospital, Sweden.
    Effects of peroxovanadate and vanadate on insulin binding, degradation and sensitivity in rat adipocytes1996In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1310, no 1, p. 103-109Article in journal (Refereed)
    Abstract [en]

    The effects of vanadate and the stable peroxovanadate compound bpV(pic) on insulin binding and degradation were investigated in rat adipocytes under conditions of ongoing receptor cycling. Both bpV(pic) and vanadate increased 125I-insulin binding to intact cells through an increase in apparent receptor affinity. The maximal effect of bpV(pic) was to increase binding approximately 4-fold (EC50 0.06 +/- 0.01 mM), whereas vanadate increased binding approximately 2-fold (EC50 1.4 +/- 0.2 mM). Removal of cell surface insulin-receptor complexes with trypsin showed that the effects on binding exerted by bpV(pic) and vanadate were due to a similar increase in both cell surface binding and intracellular accumulation of radioactivity. Both bpV(pic) and vanadate inhibited the degradation of 125I-insulin in medium containing 1% bovine serum albumin. The ratio of degraded/intact intracellular 125I-insulin was also markedly reduced by these agents, suggesting that they inhibit intracellular insulin-degrading proteases. Similar to previous findings with vanadate, bpV(pic) stimulated glucose transport and, at low concentrations, enhanced insulin sensitivity. Taken together, these data demonstrate that both bpV(pic) and vanadate inhibit insulin degradation. In addition, they significantly enhance cell surface insulin binding in rat fat cells and this is associated with an improved insulin sensitivity.

  • 44. Yu, Z W
    et al.
    Wickman, A
    Eriksson, Jan W
    Lundberg Laboratory for Diabetes Research, Department of Medicine, Göteborg University, Sahigrenska University Hospital, Sweden.
    Cryptic receptors for insulin-like growth factor II in the plasma membrane of rat adipocytes: a possible link to cellular insulin resistance1996In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1282, no 1, p. 57-62Article in journal (Refereed)
    Abstract [en]

    To further elucidate the mechanisms for short-term regulation of the receptor for insulin-like growth factor II (IGF-II), we investigated effects of insulin, cAMP and phosphatase inhibitors on cell surface 125I-IGF-II binding in rat adipocytes. Preincubation with the serine/threonine phosphatase inhibitor okadaic acid (OA, 1 microM) or the non-hydrolysable cAMP analogue N6-mbcAMP (4 mM) markedly impaired insulin-stimulated 125I-IGF-II binding. Furthermore, addition of OA enhanced the inhibitory effect exerted by N6-mbcAMP. N6-mbcAMP also induced an insensitivity to insulin which was normalized by concomitant addition of the tyrosine phosphatase inhibitor vanadate (0.5 mM). In contrast, vanadate did not affect the impairment in maximal insulin-stimulated 125I-IGF-II binding produced by either OA or N6-mbcAMP. Phospholipase C (PLC), which cleaves phospholipids at the cell surface, markedly enhanced cell surface 125I-IGF-II binding in a concentration-dependent manner. Scatchard analysis demonstrated that the effect of PLC was due to an increased number of binding sites suggesting that "cryptic' IGF-II receptors are associated with the plasma membrane (PM). PLC (5 U/ml) also reversed the N6-mbcAMP-induced decrease of 125I-IGF-II binding at a low insulin concentration (10 microU/ml). Taken together, these data indicate that cAMP, similar to its effects on the glucose transporter GLUT 4 and the insulin receptor, may increase the proportion of functionally cryptic IGF-II receptors in the PM through mechanisms involving serine phosphorylation, possibly of a docking or coupling protein. Tyrosine phosphorylation appears to exert an opposite effect promoting the full cell surface expression of receptors.

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