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Cen, Jing
Publications (8 of 8) Show all publications
Sargsyan, E., Cen, J., Roomp, K., Schneider, R. & Bergsten, P. (2018). Identification of early biological changes in palmitate-treated isolated human islets.. BMC Genomics, 19, Article ID 629.
Open this publication in new window or tab >>Identification of early biological changes in palmitate-treated isolated human islets.
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2018 (English)In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 19, article id 629Article in journal (Refereed) Published
Abstract [en]

Background: Long-term exposure to elevated levels of free fatty acids (FFAs) is deleterious for beta-cell function and may contribute to development of type 2 diabetes mellitus (T2DM). Whereas mechanisms of impaired glucose-stimulated insulin secretion (GSIS) in FFA-treated beta-cells have been intensively studied, biological events preceding the secretory failure, when GSIS is accentuated, are poorly investigated. To identify these early events, we performed genome-wide analysis of gene expression in isolated human islets exposed to fatty acid palmitate for different time periods.

Results: Palmitate-treated human islets showed decline in beta-cell function starting from day two. Affymetrix Human Transcriptome Array 2.0 identified 903 differentially expressed genes (DEGs). Mapping of the genes onto pathways using KEGG pathway enrichment analysis predicted four islet biology-related pathways enriched prior but not after the decline of islet function and three pathways enriched both prior and after the decline of islet function. DEGs from these pathways were analyzed at the transcript level. The results propose that in palmitate-treated human islets, at early time points, protective events, including up-regulation of metallothioneins, tRNA synthetases and fatty acid-metabolising proteins, dominate over deleterious events, including inhibition of fatty acid detoxification enzymes, which contributes to the enhanced GSIS. After prolonged exposure of islets to palmitate, the protective events are outweighed by the deleterious events, which leads to impaired GSIS.

Conclusions: The study identifies temporal order between different cellular events, which either promote or protect from beta-cell failure. The sequence of these events should be considered when developing strategies for prevention and treatment of the disease.

Place, publisher, year, edition, pages
BioMed Central, UK: , 2018
Keywords
palmitate, human islets, insulin secretion, Human Transcriptome Array
National Category
Cell and Molecular Biology
Research subject
Medical Cell Biology
Identifiers
urn:nbn:se:uu:diva-355082 (URN)10.1186/s12864-018-5008-z (DOI)000442532000008 ()30134843 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 279 153
Available from: 2018-06-27 Created: 2018-06-27 Last updated: 2018-10-05Bibliographically approved
Cen, J., Sargsyan, E., Forslund, A. & Bergsten, P. (2018). Mechanisms of beneficial effects of metformin on fatty acid-treated human islets. Journal of Molecular Endocrinology, 61(3), 91-99
Open this publication in new window or tab >>Mechanisms of beneficial effects of metformin on fatty acid-treated human islets
2018 (English)In: Journal of Molecular Endocrinology, ISSN 0952-5041, E-ISSN 1479-6813, Vol. 61, no 3, p. 91-99Article in journal (Refereed) Published
Abstract [en]

Elevated levels of palmitate accentuate glucose-stimulated insulin secretion (GSIS) after short-term and cause beta-cell dysfunction after prolonged exposure. We investigated whether metformin, the first-line oral drug for treatment of T2DM, has beneficial effects on FFA-treated human islets and the potential mechanisms behind the effects. Insulin secretion, oxygen consumption rate (OCR), AMPK activation, endoplasmic reticulum (ER) stress and apoptosis were examined in isolated human islets after exposure to elevated levels of palmitate in the absence or presence of metformin. Palmitate exposure doubled GSIS after 2 days but halved after 7 days compared with control. Inclusion of metformin during palmitate exposure normalized insulin secretion both after 2 and 7 days. After 2-day exposure to palmitate, OCR and the marker of the adaptive arm of ER stress response (sorcin) were significantly raised, whereas AMPK phosphorylation, markers of pro-apoptotic arm of ER stress response (p-EIF2α and CHOP) and apoptosis (cleaved caspase 3) were not affected. Presence of metformin during 2-day palmitate exposure normalized OCR and sorcin levels. After 7-day exposure to palmitate, OCR and sorcin were not significantly different from control level, p-AMPK was reduced and p-EIF2α, CHOP and cleaved caspase 3 were strongly upregulated. Presence of metformin during 7-day culture with palmitate normalized the level of p-AMPK, p-EIF2α, CHOP and cleaved caspase 3 but significantly increased the level of sorcin. Our study demonstrates that metformin prevents early insulin hypersecretion and later decrease in insulin secretion from palmitate-treated human islets by utilizing different mechanisms.

Keywords
Metformin, palmitate, human islets, insulin secretion, mitochondrial respiration, ER stress
National Category
Endocrinology and Diabetes Pharmacology and Toxicology
Research subject
Medical Cell Biology
Identifiers
urn:nbn:se:uu:diva-353691 (URN)10.1530/JME-17-0304 (DOI)000452706400005 ()30307162 (PubMedID)
Funder
Swedish Diabetes Association, DIA 2016-146EU, FP7, Seventh Framework Programme, 279 153Ernfors Foundation, 170504
Available from: 2018-06-27 Created: 2018-06-27 Last updated: 2019-01-11Bibliographically approved
Groebe, K., Cen, J., Schvartz, D., Sargsyan, E., Chowdhury, A. I., Roomp, K., . . . Bergsten, P. (2018). Palmitate-Induced Insulin Hypersecretion and Later Secretory Decline Associated with Changes in Protein Expression Patterns in Human Pancreatic Islets. Journal of Proteome Research, 17(11), 3824-3836
Open this publication in new window or tab >>Palmitate-Induced Insulin Hypersecretion and Later Secretory Decline Associated with Changes in Protein Expression Patterns in Human Pancreatic Islets
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2018 (English)In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 17, no 11, p. 3824-3836Article in journal (Refereed) Published
Abstract [en]

In obese children with high circulating concentrations of free fatty acid palmitate, we have observed that insulin levels at fasting and in response to a glucose challenge were several times higher than in obese children with low concentrations of the fatty acid as well as in lean controls. Declining and even insufficient insulin levels were observed in obese adolescents with high levels of the fatty acid. In isolated human islets exposed to palmitate we have observed insulin hypersecretion after 2 days exposure. In contrast, insulin secretion from the islets was reduced after 7 days culture in the presence of the fatty acid. This study aims at identifying islet-related biological events potentially linked with the observed insulin hypersecretion and later secretory decline in these obese children and adolescents using the islet model. We analyzed protein expression data obtained from human islets exposed to elevated palmitate levels for 2 and 7 days by an improved methodology for statistical analysis of differentially expressed proteins. Protein profiling of islet samples by liquid chromatography-tandem mass spectrometry identified 115 differentially expressed proteins (DEPs). Several DEPs including sorcin were associated with increased glucose-stimulated insulin secretion in islets after 2 days of exposure to palmitate. Similarly, several metabolic pathways including altered protein degradation, increased autophagy, altered redox condition, and hampered insulin processing were coupled to the functional impairment of islets after 7 days of culture in the presence of palmitate. Such biological events, once validated in the islets, may give rise to novel treatment strategies aiming at normalizing insulin levels in obese children with high palmitate levels, which may reduce or even prevent obesity-related type 2 diabetes mellitus.

Keywords
childhood obesity, insulin secretion, insulin hypersecretion, insulin hyposecretion, type 2 diabetes mellitus, T2DM, human pancreatic islets, palmitate, in vitro, glucose-stimulated insulin secretion, GSIS, proteomics, differential proteomic analysis, bioinform atic analysis
National Category
Endocrinology and Diabetes Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-369592 (URN)10.1021/acs.jproteome.8b00239 (DOI)000449443000020 ()30183308 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 279153
Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2018-12-19Bibliographically approved
Cen, J., Sargsyan, E. & Bergsten, P. (2017). Metformin restores insulin secretion from palmitate-treated human islets by normalising mitochondrial metabolism and reducing ER stress and apoptosis. Paper presented at 53rd Annual Meeting of the European-Association-for-the-Study-of-Diabetes (EASD), SEP 11-15, 2017, Lisbon, PORTUGAL. Diabetologia, 60, S47-S47
Open this publication in new window or tab >>Metformin restores insulin secretion from palmitate-treated human islets by normalising mitochondrial metabolism and reducing ER stress and apoptosis
2017 (English)In: Diabetologia, ISSN 0012-186X, E-ISSN 1432-0428, Vol. 60, p. S47-S47Article in journal, Meeting abstract (Other academic) Published
National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-346986 (URN)000408315000102 ()
Conference
53rd Annual Meeting of the European-Association-for-the-Study-of-Diabetes (EASD), SEP 11-15, 2017, Lisbon, PORTUGAL
Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-03-23Bibliographically approved
Staaf, J., Labmayr, V., Paulmichl, K., Manell, H., Cen, J., Ciba, I., . . . Kullberg, J. (2017). Pancreatic Fat Is Associated With Metabolic Syndrome and Visceral Fat but Not Beta-Cell Function or Body Mass Index in Pediatric Obesity. Pancreas, 46(3), 358-365
Open this publication in new window or tab >>Pancreatic Fat Is Associated With Metabolic Syndrome and Visceral Fat but Not Beta-Cell Function or Body Mass Index in Pediatric Obesity
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2017 (English)In: Pancreas, ISSN 0885-3177, E-ISSN 1536-4828, Vol. 46, no 3, p. 358-365Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: Adolescents with obesity have increased risk of type 2 diabetes and metabolic syndrome (MetS). Pancreatic fat has been related to these conditions; however, little is known about associations in pediatric obesity. The present study was designed to explore these associations further.

METHODS: We examined 116 subjects, 90 with obesity. Anthropometry, MetS, blood samples, and oral glucose tolerance tests were assessed using standard techniques. Pancreatic fat fraction (PFF) and other fat depots were quantified using magnetic resonance imaging.

RESULTS: The PFF was elevated in subjects with obesity. No association between PFF and body mass index-standard deviation score (BMI-SDS) was found in the obesity subcohort. Pancreatic fat fraction correlated to Insulin Secretion Sensitivity Index-2 and Homeostatic Model Assessment of Insulin Resistance in simple regression; however, when using adjusted regression and correcting for BMI-SDS and other fat compartments, PFF correlated only to visceral adipose tissue and fasting glucose. Highest levels of PFF were found in subjects with obesity and MetS.

CONCLUSIONS: In adolescents with obesity, PFF is elevated and associatedto MetS, fasting glucose, and visceral adipose tissue but not to beta-cellfunction, glucose tolerance, or BMI-SDS. This study demonstrates thatconclusions regarding PFF and its associations depend on the body massfeatures of the cohort.

Keywords
pancreatic fat, pediatric obesity, beta-cell function, metabolic syndrome, body mass index-standard deviation score
National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-311308 (URN)10.1097/MPA.0000000000000771 (DOI)000394448600018 ()27941426 (PubMedID)
Funder
Swedish Research Council, 72X-14019 2012-2330 2011-4423Swedish Diabetes AssociationEU, FP7, Seventh Framework Programme, 279153
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2017-04-26Bibliographically approved
Manell, H., Staaf, J., Manukyan, L., Kristinsson, H., Cen, J., Stenlid, R., . . . Bergsten, P. (2016). Altered Plasma Levels of Glucagon, GLP-1 and Glicentin During OGTT in Adolescents With Obesity and Type 2 Diabetes. Journal of Clinical Endocrinology and Metabolism, 101(3), 1181-1189
Open this publication in new window or tab >>Altered Plasma Levels of Glucagon, GLP-1 and Glicentin During OGTT in Adolescents With Obesity and Type 2 Diabetes
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2016 (English)In: Journal of Clinical Endocrinology and Metabolism, ISSN 0021-972X, E-ISSN 1945-7197, Vol. 101, no 3, p. 1181-1189Article in journal (Refereed) Published
Abstract [en]

CONTEXT: Proglucagon-derived hormones are important for glucose metabolism, but little is known about them in pediatric obesity and type 2 diabetes mellitus (T2DM).

OBJECTIVE: Fasting and postprandial levels of proglucagon-derived peptides glucagon, GLP-1, and glicentin in adolescents with obesity across the glucose tolerance spectrum were investigated.

DESIGN: This was a cross-sectional study with plasma hormone levels quantified at fasting and during an oral glucose tolerance test (OGTT).

SETTING: This study took place in a pediatric obesity clinic at Uppsala University Hospital, Sweden.

PATIENTS AND PARTICIPANTS: Adolescents with obesity, age 10-18 years, with normal glucose tolerance (NGT, n = 23), impaired glucose tolerance (IGT, n = 19), or T2DM (n = 4) and age-matched lean adolescents (n = 19) were included.

MAIN OUTCOME MEASURES: Outcome measures were fasting and OGTT plasma levels of insulin, glucagon, active GLP-1, and glicentin.

RESULTS: Adolescents with obesity and IGT had lower fasting GLP-1 and glicentin levels than those with NGT (0.25 vs 0.53 pM, P < .05; 18.2 vs 23.6 pM, P < .01) and adolescents with obesity and T2DM had higher fasting glucagon levels (18.1 vs 10.1 pM, P < .01) than those with NGT. During OGTT, glicentin/glucagon ratios were lower in adolescents with obesity and NGT than in lean adolescents (P < .01) and even lower in IGT (P < .05) and T2DM (P < .001).

CONCLUSIONS: Obese adolescents with IGT have lowered fasting GLP-1 and glicentin levels. In T2DM, fasting glucagon levels are elevated, whereas GLP-1 and glicentin levels are maintained low. During OGTT, adolescents with obesity have more products of pancreatically than intestinally cleaved proglucagon (ie, more glucagon and less GLP-1) in the plasma. This shift becomes more pronounced when glucose tolerance deteriorates.

National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-292749 (URN)10.1210/jc.2015-3885 (DOI)000378811300051 ()26745255 (PubMedID)
Funder
VINNOVAEU, FP7, Seventh Framework Programme, 279153Swedish Diabetes Association, DIA 2013-043
Available from: 2016-05-09 Created: 2016-05-09 Last updated: 2019-03-28Bibliographically approved
Cen, J., Sargsyan, E. & Bergsten, P. (2016). Fatty acids stimulate insulin secretion from human pancreatic islets at fasting glucose concentrations via mitochondria-dependent and -independent mechanisms. Nutrition & Metabolism, 13, Article ID 59.
Open this publication in new window or tab >>Fatty acids stimulate insulin secretion from human pancreatic islets at fasting glucose concentrations via mitochondria-dependent and -independent mechanisms
2016 (English)In: Nutrition & Metabolism, ISSN 1743-7075, E-ISSN 1743-7075, Vol. 13, article id 59Article in journal (Refereed) Published
Abstract [en]

Background: Free fatty acids (FFAs) acutely stimulate insulin secretion from pancreatic islets. Conflicting results have been presented regarding this effect at non-stimulatory glucose concentration, however. The aim of our study was to investigate how long-chain FFAs affect insulin secretion from isolated human pancreatic islets in the presence of physiologically fasting glucose concentrations and to explore the contribution of mitochondria to the effects on secretion. Methods: Insulin secretion from human pancreatic islets was measured from short-term static incubation or perfusion system at fasting glucose concentration (5.5 mM) with or without 4 different FFAs (palmitate, palmitoleate, stearate, and oleate). The contribution of mitochondrial metabolism to the effects of fatty acid-stimulated insulin secretion was explored. Results: The average increase in insulin secretion, measured from statically incubated and dynamically perifused human islets, was about 2-fold for saturated free fatty acids (SFAs) (palmitate and stearate) and 3-fold for mono-unsaturated free fatty acids (MUFAs) (palmitoleate and oleate) compared with 5.5 mmol/l glucose alone. Accordingly, MUFAs induced 50 % and SFAs 20 % higher levels of oxygen consumption compared with islets exposed to 5.5 mmol/l glucose alone. The effect was due to increased glycolysis. When glucose was omitted from the medium, addition of the FFAs did not affect oxygen consumption. However, the FFAs still stimulated insulin secretion from the islets although secretion was more than halved. The mitochondria-independent action was via fatty acid metabolism and FFAR1/GPR40 signaling. Conclusions: The findings suggest that long-chain FFAs acutely induce insulin secretion from human islets at physiologically fasting glucose concentrations, with MUFAs being more potent than SFAs, and that this effect is associated with increased glycolytic flux and mitochondrial respiration.

Keywords
Insulin secretion, Human pancreatic islets, Saturated fatty acids, Monounsaturated fatty acids, Mitochondrial respiration
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-305932 (URN)10.1186/s12986-016-0119-5 (DOI)000384583400001 ()27582778 (PubMedID)
Available from: 2016-11-14 Created: 2016-10-24 Last updated: 2018-06-27Bibliographically approved
Staaf, J., Labmayr, V., Paulmichl, K., Ohlsson, H., Cen, J., Ciba, I., . . . Kullberg, J. (2015). Pancreatic Fat is Associated with Metabolic Syndrome and Visceral Adipose Tissue but not Beta-Cell Function or Body Mass Index in Paediatric Obesity. Acta Paediatrica, 104(S466), 2-2
Open this publication in new window or tab >>Pancreatic Fat is Associated with Metabolic Syndrome and Visceral Adipose Tissue but not Beta-Cell Function or Body Mass Index in Paediatric Obesity
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2015 (English)In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 104, no S466, p. 2-2Article in journal, Meeting abstract (Other academic) Published
Keywords
childhood obesity, insulin sensitivity, metabolism, visceral fat
National Category
Pediatrics
Identifiers
urn:nbn:se:uu:diva-267488 (URN)000362512600002 ()
Note

Meeting Abstract: OP01

Available from: 2015-12-14 Created: 2015-11-24 Last updated: 2017-12-01Bibliographically approved
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