uu.seUppsala University Publications
Change search
Refine search result
1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Li, Jia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Shuai, Hongyan
    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.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Oscillations of sub-membrane ATP in glucose-stimulated beta cells depend on negative feedback from Ca2+2013In: Diabetologia, ISSN 0012-186X, E-ISSN 1432-0428, Vol. 56, no 7, p. 1577-1586Article in journal (Refereed)
    Abstract [en]

    ATP links changes in glucose metabolism to electrical activity, Ca2+ signalling and insulin secretion in pancreatic beta cells. There is evidence that beta cell metabolism oscillates, but little is known about ATP dynamics at the plasma membrane, where regulation of ion channels and exocytosis occur. The sub-plasma-membrane ATP concentration ([ATP](pm)) was recorded in beta cells in intact mouse and human islets using total internal reflection microscopy and the fluorescent reporter Perceval. Glucose dose-dependently increased [ATP](pm) with half-maximal and maximal effects at 5.2 and 9 mmol/l, respectively. Additional elevations of glucose to 11 to 20 mmol/l promoted pronounced [ATP](pm) oscillations that were synchronised between neighbouring beta cells. [ATP](pm) increased further and the oscillations disappeared when voltage-dependent Ca2+ influx was prevented. In contrast, K+-depolarisation induced prompt lowering of [ATP](pm). Simultaneous recordings of [ATP](pm) and the sub-plasma-membrane Ca2+ concentration ([Ca2+](pm)) during the early glucose-induced response revealed that the initial [ATP](pm) elevation preceded, and was temporarily interrupted by the rise of [Ca2+](pm). During subsequent glucose-induced oscillations, the increases of [Ca2+](pm) correlated with lowering of [ATP](pm). In beta cells, glucose promotes pronounced oscillations of [ATP](pm), which depend on negative feedback from Ca2+ (.) The bidirectional interplay between these messengers in the sub-membrane space generates the metabolic and ionic oscillations that underlie pulsatile insulin secretion.

  • 2.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Constitutive GLP-1-receptor signaling contributes to basal and glucose-stimulated cAMP formation in β-cells: Constitutive GLP-1 receptor signaling in β-cellsIn: Article in journal (Other (popular science, discussion, etc.))
  • 3.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Studies of cAMP and Ca2+ signaling in pancreatic islet cells2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The blood glucose-lowering and -elevating hormones insulin and glucagon are released from the pancreatic islet β- and α-cells, respectively. The intracellular messengers Ca2+ and cAMP have central roles in controlling the secretion of both hormones, but the underlying mechanisms are incompletely understood. A powerful approach to gain further insight is to study the messengers in individual cells within pancreatic islets, provided that each cell can be identified. To facilitate such studies, adenoviral vectors were generated for expression of fluorescent proteins controlled by the insulin and preproglucagon promoters, as well as the somatostatin and pancreatic polypeptide promoters that identify the other two major islet cell types, δ- and PP-cells. Recordings of cAMP and Ca2+ concentration changes with fluorescent reporters demonstrated that cells expressing identification markers responded as expected to well-known stimuli and modulators of the two messengers. Glucose-induced Ca2+ oscillations in β-cells were found to be synchronized with those in δ-cells, and two subpopulations of α-cells with different Ca2+ regulation by glucose were identified. Mouse and human β-cells responded to the insulinotropic hormones glucagon, GIP and GLP-1 with elevations of cAMP. Most α-cells reacted similarly to GIP, whereas only a subpopulation – larger among human than mouse α-cells - responded to glucagon and GLP-1. The GLP-1-receptor antagonist exendin-(9-39) suppressed both GLP-1- and glucagon-induced cAMP elevations in β-cells. Since exendin-(9-39) did not antagonize glucagon receptors, glucagon apparently activates GLP-1 receptors in β-cells. Even in the absence of glucagon/GLP-1, exendin-(9-39) reduced cAMP increases obtained by glucose stimulation or elevation of Ca2+. This effect was attributable to constitutive GLP-1-receptor activity rather than paracrine effects. Exendin-(9-39) also inhibited glucose-induced insulin release, highlighting the importance of cAMP formation in nutrient-stimulated secretion. Simultaneous recordings of cAMP and Ca2+ showed a complex and variable interrelationship between the messengers and the cAMP precursor ATP in β-cells. Depolarization-induced Ca2+ increases inhibited forskolin-, IBMX- and GLP-1-induced cAMP elevations. This cAMP lowering in part reflected suppression of the Ca2+-sensitive activity of adenylyl cyclases AC5 and 6, but also autocrine signaling induced by Ca2+-triggered exocytosis of insulin and adenine nucleotides, whose receptors activate phosphodiesterases and inhibit adenylyl cyclases, respectively.

    List of papers
    1. Fluorescent protein vectors for pancreatic islet cell identification in live-cell imaging
    Open this publication in new window or tab >>Fluorescent protein vectors for pancreatic islet cell identification in live-cell imaging
    Show others...
    2016 (English)In: Pflügers Archiv: European Journal of Physiology, ISSN 0031-6768, E-ISSN 1432-2013, Vol. 468, no 10, p. 1765-1777Article in journal (Refereed) Published
    Abstract [en]

    The islets of Langerhans contain different types of endocrine cells, which are crucial for glucose homeostasis. beta- and alpha-cells that release insulin and glucagon, respectively, are most abundant, whereas somatostatin-producing delta-cells and particularly pancreatic polypeptide-releasing PP-cells are more scarce. Studies of islet cell function are hampered by difficulties to identify the different cell types, especially in live-cell imaging experiments when immunostaining is unsuitable. The aim of the present study was to create a set of vectors for fluorescent protein expression with cell-type-specific promoters and evaluate their applicability in functional islet imaging. We constructed six adenoviral vectors for expression of red and green fluorescent proteins controlled by the insulin, preproglucagon, somatostatin, or pancreatic polypeptide promoters. After transduction of mouse and human islets or dispersed islet cells, a majority of the fluorescent cells also immunostained for the appropriate hormone. Recordings of the sub-plasma membrane Ca2+ and cAMP concentrations with a fluorescent indicator and a protein biosensor, respectively, showed that labeled cells respond to glucose and other modulators of secretion and revealed a striking variability in Ca2+ signaling among alpha-cells. The measurements allowed comparison of the phase relationship of Ca2+ oscillations between different types of cells within intact islets. We conclude that the fluorescent protein vectors allow easy identification of specific islet cell types and can be used in live-cell imaging together with organic dyes and genetically encoded biosensors. This approach will facilitate studies of normal islet physiology and help to clarify molecular defects and disturbed cell interactions in diabetic islets.

    Keywords
    Islets, alpha-cell, beta-cell, delta-cell, PP-cell, Insulin, Glucagon, Somatostatin, Pancreatic polypeptide, Ca2+, cAMP
    National Category
    Physiology
    Identifiers
    urn:nbn:se:uu:diva-306746 (URN)10.1007/s00424-016-1864-z (DOI)000384425500011 ()27539300 (PubMedID)
    Funder
    Swedish Research Council, 325-2012-6778, 55X-06240Swedish Diabetes AssociationNovo NordiskEXODIAB - Excellence of Diabetes Research in Sweden
    Available from: 2016-11-09 Created: 2016-11-03 Last updated: 2018-12-11Bibliographically approved
    2. Constitutive GLP-1-receptor signaling contributes to basal and glucose-stimulated cAMP formation in β-cells: Constitutive GLP-1 receptor signaling in β-cells
    Open this publication in new window or tab >>Constitutive GLP-1-receptor signaling contributes to basal and glucose-stimulated cAMP formation in β-cells: Constitutive GLP-1 receptor signaling in β-cells
    (English)In: Article in journal (Other (popular science, discussion, etc.)) Submitted
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-368723 (URN)
    Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11
    3. Effects of Ca2+ and autocrine signals on cAMP dynamics in β-cells
    Open this publication in new window or tab >>Effects of Ca2+ and autocrine signals on cAMP dynamics in β-cells
    (English)Manuscript (preprint) (Other (popular science, discussion, etc.))
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-368721 (URN)
    Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11
    4. Glucagon and GLP-1 evoke cAMP elevations in sub-populations of mouse and human α-cells
    Open this publication in new window or tab >>Glucagon and GLP-1 evoke cAMP elevations in sub-populations of mouse and human α-cells
    (English)Manuscript (preprint) (Other (popular science, discussion, etc.))
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-368722 (URN)
    Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-20
  • 4.
    Shuai, Hongyan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Effects of Ca2+ and autocrine signals on cAMP dynamics in β-cellsManuscript (preprint) (Other (popular science, discussion, etc.))
  • 5.
    Shuai, Hongyan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Glucagon and GLP-1 evoke cAMP elevations in sub-populations of mouse and human α-cellsManuscript (preprint) (Other (popular science, discussion, etc.))
  • 6.
    Tian, Geng
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Sol, Eri Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Xu, Yunjian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Impaired cAMP generation contributes to defective glucose-stimulated insulin secretion after long-term exposure to palmitate2015In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 64, no 3, p. 904-915Article in journal (Refereed)
    Abstract [en]

    Chronic palmitate exposure impairs glucose-stimulated insulin secretion and other aspects of β-cell function but the underlying mechanisms are not known. Using various live-cell fluorescence imaging approaches we show here that long-term palmitate treatment influences cAMP signaling in pancreatic β-cells. Glucose stimulation of mouse and human β-cells induced oscillations of the sub-plasma-membrane cAMP concentration but after 48 h exposure to palmitate, most β-cells failed to increase cAMP in response to glucose. In contrast, GLP-1-triggered cAMP formation and glucose- and depolarization-induced increases in cytoplasmic Ca2+ concentration were unaffected by the fatty acid treatment. Insulin secretion from control β-cells was pulsatile but the response deteriorated after long-term palmitate exposure. Palmitate-treated mouse islets showed reduced expression of adenylyl cyclase 9 and knockdown of this protein in insulinoma cells reduced the glucose-stimulated cAMP response and insulin secretion. We conclude that impaired glucose-induced generation of cAMP is an important determinant of defective insulin secretion after chronic palmitate exposure.

  • 7.
    Tian, Geng
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Sågetorp, Jenny
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Xu, Yunjian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Degerman, Eva
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Role of phosphodiesterases in the shaping of sub-plasma-membrane cAMP oscillations and pulsatile insulin secretion2012In: Journal of Cell Science, ISSN 0021-9533, E-ISSN 1477-9137, Vol. 125, no 21, p. 5084-5095Article in journal (Refereed)
    Abstract [en]

    Specificity and versatility in cyclic AMP (cAMP) signalling are governed by the spatial localisation and temporal dynamics of the signal. Phosphodiesterases (PDEs) are important for shaping cAMP signals by hydrolyzing the nucleotide. In pancreatic β-cells, glucose triggers sub-plasma-membrane cAMP oscillations, which are important for insulin secretion, but the mechanisms underlying the oscillations are poorly understood. Here, we investigated the role of different PDEs in the generation of cAMP oscillations by monitoring the concentration of cAMP in the sub-plasma-membrane space ([cAMP](pm)) with ratiometric evanescent wave microscopy in MIN6 cells or mouse pancreatic β-cells expressing a fluorescent translocation biosensor. The general PDE inhibitor IBMX increased [cAMP](pm), and whereas oscillations were frequently observed at 50 µM IBMX, 300 µM-1 mM of the inhibitor caused a stable increase in [cAMP](pm). The [cAMP](pm) was nevertheless markedly suppressed by the adenylyl cyclase inhibitor 2',5'-dideoxyadenosine, indicating IBMX-insensitive cAMP degradation. Among IBMX-sensitive PDEs, PDE3 was most important for maintaining a low basal level of [cAMP](pm) in unstimulated cells. After glucose induction of [cAMP](pm) oscillations, inhibitors of PDE1, PDE3 and PDE4 inhibitors the average cAMP level, often without disturbing the [cAMP](pm) rhythmicity. Knockdown of the IBMX-insensitive PDE8B by shRNA in MIN6 cells increased the basal level of [cAMP](pm) and prevented the [cAMP](pm)-lowering effect of 2',5'-dideoxyadenosine after exposure to IBMX. Moreover, PDE8B-knockdown cells showed reduced glucose-induced [cAMP](pm) oscillations and loss of the normal pulsatile pattern of insulin secretion. It is concluded that [cAMP](pm) oscillations in β-cells are caused by periodic variations in cAMP generation, and that several PDEs, including PDE1, PDE3 and the IBMX-insensitive PDE8B, are required for shaping the sub-membrane cAMP signals and pulsatile insulin release.

  • 8.
    Yu, Qian
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Ahooghalandari, Parvin
    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.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Glucose controls glucagon secretion by directly modulating cAMP in alpha cells2019In: Diabetologia, ISSN 0012-186X, E-ISSN 1432-0428, Vol. 62, no 7, p. 1212-1224Article in journal (Refereed)
    Abstract [en]

    Aims/hypothesis

    Glucagon is critical for normal glucose homeostasis and aberrant secretion of the hormone aggravates dysregulated glucose control in diabetes. However, the mechanisms by which glucose controls glucagon secretion from pancreatic alpha cells remain elusive. The aim of this study was to investigate the role of the intracellular messenger cAMP in alpha-cell-intrinsic glucose regulation of glucagon release.

    Methods

    Subplasmalemmal cAMP and Ca2+ concentrations were recorded in isolated and islet-located alpha cells using fluorescent reporters and total internal reflection microscopy. Glucagon secretion from mouse islets was measured using ELISA.

    Results

    Glucose induced Ca2+-independent alterations of the subplasmalemmal cAMP concentration in alpha cells that correlated with changes in glucagon release. Glucose-lowering-induced stimulation of glucagon secretion thus corresponded to an elevation in cAMP that was independent of paracrine signalling from insulin or somatostatin. Imposed cAMP elevations stimulated glucagon secretion and abolished inhibition by glucose elevation, while protein kinase A inhibition mimicked glucose suppression of glucagon release.

    Conclusions/interpretation

    Glucose concentrations in the hypoglycaemic range control glucagon secretion by directly modulating the cAMP concentration in alpha cells independently of paracrine influences. These findings define a novel mechanism for glucose regulation of glucagon release that underlies recovery from hypoglycaemia and may be disturbed in diabetes.

  • 9.
    Yu, Qian
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Ahooghalandari, Parvin
    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.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Glucose controls glucagon secretion by directly modulating cAMP in α‑cellsIn: Article in journal (Other (popular science, discussion, etc.))
  • 10.
    Yu, Qian
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Shuai, Hongyan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Ahooghalandari, Parvin
    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.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Glucose lowers cAMP to inhibit glucagon secretion by a direct effect on alpha cells2016In: Diabetologia, ISSN 0012-186X, E-ISSN 1432-0428, Vol. 59, p. S266-S267Article in journal (Refereed)
1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf