scholarly journals Pericytes contribute to the islet basement membranes to promote beta-cell gene expression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lina Sakhneny ◽  
Alona Epshtein ◽  
Limor Landsman
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
Basement Membranes ◽  
Cell Physiology ◽  
Β Cells ◽  
Β Cell ◽  
Cell Clustering ◽  
Β Cell Function ◽  
Cell Gene Expression ◽  
Glucose Stimulated Insulin Secretion

Abstractβ-Cells depend on the islet basement membrane (BM). While some islet BM components are produced by endothelial cells (ECs), the source of others remains unknown. Pancreatic pericytes directly support β-cells through mostly unidentified secreted factors. Thus, we hypothesized that pericytes regulate β-cells through the production of BM components. Here, we show that pericytes produce multiple components of the mouse pancreatic and islet interstitial and BM matrices. Several of the pericyte-produced ECM components were previously implicated in β-cell physiology, including collagen IV, laminins, proteoglycans, fibronectin, nidogen, and hyaluronan. Compared to ECs, pancreatic pericytes produce significantly higher levels of α2 and α4 laminin chains, which constitute the peri-islet and vascular BM. We further found that the pericytic laminin isoforms differentially regulate mouse β-cells. Whereas α2 laminins promoted islet cell clustering, they did not affect gene expression. In contrast, culturing on Laminin-421 induced the expression of β-cell genes, including Ins1, MafA, and Glut2, and significantly improved glucose-stimulated insulin secretion. Thus, alongside ECs, pericytes are a significant source of the islet BM, which is essential for proper β-cell function.

scholarly journals Translational factor eIF4G1 regulates glucose homeostasis and pancreatic β-cell function

2020 ◽  
Author(s):  
Ada Admin ◽  
Seokwon Jo ◽  
Amber Lockridge ◽  
Ramkumar Mohan ◽  
Nicholas Esch ◽  
...  
Keyword(s):  
Glucose Homeostasis ◽  
Cell Function ◽  
Scaffolding Protein ◽  
Insulin Content ◽  
Insulin Biosynthesis ◽  
Cell Physiology ◽  
Β Cells ◽  
Β Cell ◽  
Initiation Complex ◽  
Β Cell Function

Protein translation is essential for cell physiology, and dysregulation of this process has been linked to aging-related diseases such as type 2 diabetes. Reduced protein level of a requisite scaffolding protein of the initiation complex, eIF4G1, downstream of nutrients and insulin signaling, is associated with diabetes in both humans and mice. In the present study, we tested the hypothesis that eIF4G1 is critical for β-cell function and glucose homeostasis by genetically ablating eIF4G1 specifically in β-cells <i>in vivo</i> (βeIF4G1KO). Adult male and female βeIF4G1KO mice displayed glucose intolerance but normal insulin sensitivity. β-cell mass was normal under steady state and under metabolic stress by diet-induced obesity, but we observed increases in both proliferation and apoptosis in β-cells of βeIF4G1KO. We uncovered deficits in insulin secretion, partly due to reduced mitochondrial oxygen consumption rate, glucose-stimulated Ca<sup>2+</sup> flux, and reduced insulin content associated with loss of eIF4E, the mRNA 5’-cap binding protein of the initiation complex and binding partner of eIF4G1. Genetic reconstitution of eIF4E in single β-cells or intact islets of βeIF4G1KO mice recovers insulin content, implicating an unexplored role for eIF4G1/eIF4E in insulin biosynthesis. Altogether these data demonstrate an essential role for the translational factor eIF4G1 on glucose homeostasis and β-cell function.

scholarly journals Emerging role of testosterone in pancreatic β cell function and insulin secretion

2019 ◽  
Vol 240 (3) ◽  
pp. R97-R105 ◽  
Author(s):  
Weiwei Xu ◽  
Jamie Morford ◽  
Franck Mauvais-Jarvis
Keyword(s):  
Insulin Secretion ◽  
Metabolic Regulation ◽  
Cell Function ◽  
Visceral Obesity ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucagon Like Peptide 1 ◽  
Glucose Stimulated Insulin Secretion

One of the most sexually dimorphic aspects of metabolic regulation is the bidirectional modulation of glucose homeostasis by testosterone in male and females. Severe testosterone deficiency predisposes men to type 2 diabetes (T2D), while in contrast, androgen excess predisposes women to hyperglycemia. The role of androgen deficiency and excess in promoting visceral obesity and insulin resistance in men and women respectively is well established. However, although it is established that hyperglycemia requires β cell dysfunction to develop, the role of testosterone in β cell function is less understood. This review discusses recent evidence that the androgen receptor (AR) is present in male and female β cells. In males, testosterone action on AR in β cells enhances glucose-stimulated insulin secretion by potentiating the insulinotropic action of glucagon-like peptide-1. In females, excess testosterone action via AR in β cells promotes insulin hypersecretion leading to oxidative injury, which in turn predisposes to T2D.

Can Functionally Mature Islet β-Cells Be Derived from Pluripotent Stem Cells? – A Step Towards Ready-To-Use β-Cells in Type 1 Diabetes

2020 ◽  
Vol 15 ◽  
Author(s):  
Bishnu K Khand ◽  
Ramesh R Bhonde
Keyword(s):  
Stem Cells ◽  
Type 1 Diabetes ◽  
Pluripotent Stem Cells ◽  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion

: Pluripotent Stem Cells [PSCs] are emerging as an excellent cellular source for treatment of many degenerative diseases such as diabetes, ischemic heart failure, Alzheimer’s disease. PSC-derived pancreatic islet β-cells appear to be as a promising therapy for type 1 diabetes patients with impaired β-cell function. Several protocols have been developed to derive β-cells from PSCs. However, these protocols produce β-like cells that show low glucose stimulated insulin secretion [GSIS] function and mirror GSIS profile of functionally immature neonatal β-cells. Several studies have documented a positive correlation between the sirtuins [a family of ageing-related proteins] and the GSIS function of adult β-cells. We are of the view that GSIS function of PSC-derived β-like cells could be enhanced by improving the function of sirtuins in them. Studying the sirtuin expression and activation pattern during the β-cell development and inclusion of the sirtuin activator and inhibitor cocktail [specific to a developmental stage] in the present protocols may help us derive functionally mature, ready-to-use β-cells in-vitro making them suitable for transplantation in type 1 diabetes.

scholarly journals AMP-activated protein kinase agonist dose dependently improves function and reduces apoptosis in glucotoxic β-cells without changing triglyceride levels

2008 ◽  
Vol 41 (3) ◽  
pp. 187-194 ◽  
Author(s):  
Hanna K Nyblom ◽  
Ernest Sargsyan ◽  
Peter Bergsten
Keyword(s):  
Protein Kinase ◽  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Downstream Target ◽  
Homologous Protein ◽  
Prolonged Culture ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion ◽  
Amp Activated Protein Kinase

Prolonged hyperglycaemia leads to impaired glucose-stimulated insulin secretion (GSIS) and apoptosis in insulin-producing β-cells. The detrimental effects have been connected with glucose-induced lipid accumulation in the β-cell. AMP-activated protein kinase (AMPK) agonist, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), promotes utilization of nutrient stores for energy production. It was tested how impaired GSIS and elevated apoptosis observed in insulinoma (INS)-1E cells after prolonged culture at 27 mM glucose were affected by the inclusion of 0.3 or 1 mM AICAR during culture. Glucose-induced impairment of insulin release was reverted by the inclusion of 0.3 but not 1 mM AICAR, which did not affect insulin content. The glucose-induced rise in triglyceride (TG) content observed in the cells cultured at 27 mM glucose was not altered by the inclusion of either 0.3 or 1 mM AICAR. Inclusion of 1 but not 0.3 mM AICAR during culture induced phosphorylation of AMPK and its downstream target acyl-CoA carboxylase. Phosphorylation was paralleled by reduced number of apoptotic cells and lowered expression of pro-apoptotic C/EBP homologous protein (CHOP). In conclusion, AICAR dose dependently improves β-cell function and reduces apoptosis in β-cells exposed to prolonged hyperglycaemia without changing TG levels.

scholarly journals Translational factor eIF4G1 regulates glucose homeostasis and pancreatic β-cell function

2020 ◽  
Author(s):  
Ada Admin ◽  
Seokwon Jo ◽  
Amber Lockridge ◽  
Ramkumar Mohan ◽  
Nicholas Esch ◽  
...  
Keyword(s):  
Glucose Homeostasis ◽  
Cell Function ◽  
Scaffolding Protein ◽  
Insulin Content ◽  
Insulin Biosynthesis ◽  
Cell Physiology ◽  
Β Cells ◽  
Β Cell ◽  
Initiation Complex ◽  
Β Cell Function

Protein translation is essential for cell physiology, and dysregulation of this process has been linked to aging-related diseases such as type 2 diabetes. Reduced protein level of a requisite scaffolding protein of the initiation complex, eIF4G1, downstream of nutrients and insulin signaling, is associated with diabetes in both humans and mice. In the present study, we tested the hypothesis that eIF4G1 is critical for β-cell function and glucose homeostasis by genetically ablating eIF4G1 specifically in β-cells <i>in vivo</i> (βeIF4G1KO). Adult male and female βeIF4G1KO mice displayed glucose intolerance but normal insulin sensitivity. β-cell mass was normal under steady state and under metabolic stress by diet-induced obesity, but we observed increases in both proliferation and apoptosis in β-cells of βeIF4G1KO. We uncovered deficits in insulin secretion, partly due to reduced mitochondrial oxygen consumption rate, glucose-stimulated Ca<sup>2+</sup> flux, and reduced insulin content associated with loss of eIF4E, the mRNA 5’-cap binding protein of the initiation complex and binding partner of eIF4G1. Genetic reconstitution of eIF4E in single β-cells or intact islets of βeIF4G1KO mice recovers insulin content, implicating an unexplored role for eIF4G1/eIF4E in insulin biosynthesis. Altogether these data demonstrate an essential role for the translational factor eIF4G1 on glucose homeostasis and β-cell function.

scholarly journals STAT3 Regulates Mitochondrial Gene Expression in Pancreatic β-Cells and its Deficiency Induces Glucose Intolerance in Obesity

2021 ◽  
Author(s):  
Anaïs Schaschkow ◽  
Lokman Pang ◽  
Valerie Vandenbempt ◽  
Bernat Elvira ◽  
Sara A. Litwak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Glucose Intolerance ◽  
High Fat Diet ◽  
Cell Function ◽  
Mitochondrial Gene ◽  
High Fat ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Deficient Mice

Most obese and insulin-resistant individuals do not develop diabetes. This is the result of the capacity of β-cells to adapt and produce enough insulin to cover the needs of the organism. The underlying mechanism of β-cell adaptation in obesity, however, remains unclear. Previous studies have suggested a role for STAT3 in mediating β-cell development and human glucose homeostasis, but little is known about STAT3 in β-cells in obesity. We observed enhanced cytoplasmic expression of STAT3 in severely obese and diabetic subjects. To address the functional role of STAT3 in adult β-cells, we generated mice with tamoxifen-inducible partial or full deletion of STAT3 in β-cells and fed them a high-fat diet before analysis. Interestingly, β-cell heterozygous and homozygous STAT3-deficient mice showed glucose intolerance when fed a high-fat diet. Gene expression analysis by RNA-Seq showed reduced expression of mitochondrial genes in STAT3 knocked down human EndoC-βH1 cells and was confirmed in FACS-purified β-cells from obese STAT3-deficient mice. Moreover, silencing of STAT3 impaired mitochondria activity in EndoC-βH1 cells and human islets, suggesting a mechanism for STAT3-modulated β-cell function. We propose STAT3 as a regulator of β-cell function, improving glucose-induced insulin secretion in obesity.

scholarly journals STAT3 Regulates Mitochondrial Gene Expression in Pancreatic β-Cells and its Deficiency Induces Glucose Intolerance in Obesity

2021 ◽  
Author(s):  
Anaïs Schaschkow ◽  
Lokman Pang ◽  
Valerie Vandenbempt ◽  
Bernat Elvira ◽  
Sara A. Litwak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Glucose Intolerance ◽  
High Fat Diet ◽  
Cell Function ◽  
Mitochondrial Gene ◽  
High Fat ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Deficient Mice

Most obese and insulin-resistant individuals do not develop diabetes. This is the result of the capacity of β-cells to adapt and produce enough insulin to cover the needs of the organism. The underlying mechanism of β-cell adaptation in obesity, however, remains unclear. Previous studies have suggested a role for STAT3 in mediating β-cell development and human glucose homeostasis, but little is known about STAT3 in β-cells in obesity. We observed enhanced cytoplasmic expression of STAT3 in severely obese and diabetic subjects. To address the functional role of STAT3 in adult β-cells, we generated mice with tamoxifen-inducible partial or full deletion of STAT3 in β-cells and fed them a high-fat diet before analysis. Interestingly, β-cell heterozygous and homozygous STAT3-deficient mice showed glucose intolerance when fed a high-fat diet. Gene expression analysis by RNA-Seq showed reduced expression of mitochondrial genes in STAT3 knocked down human EndoC-βH1 cells and was confirmed in FACS-purified β-cells from obese STAT3-deficient mice. Moreover, silencing of STAT3 impaired mitochondria activity in EndoC-βH1 cells and human islets, suggesting a mechanism for STAT3-modulated β-cell function. We propose STAT3 as a regulator of β-cell function, improving glucose-induced insulin secretion in obesity.

scholarly journals Connective tissue growth factor is critical for proper β-cell function and pregnancy-induced β-cell hyperplasia in adult mice

2016 ◽  
Vol 311 (3) ◽  
pp. E564-E574 ◽  
Author(s):  
Raymond C. Pasek ◽  
Jennifer C. Dunn ◽  
Joseph M. Elsakr ◽  
Mounika Aramandla ◽  
Anveetha R. Matta ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Insulin Secretion ◽  
Growth Factor ◽  
Gestational Diabetes ◽  
Cell Function ◽  
Tissue Growth ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion

During pregnancy, maternal β-cells undergo compensatory changes, including increased β-cell mass and enhanced glucose-stimulated insulin secretion. Failure of these adaptations to occur results in gestational diabetes mellitus. The secreted protein connective tissue growth factor (CTGF) is critical for normal β-cell development and promotes regeneration after partial β-cell ablation. During embryogenesis, CTGF is expressed in pancreatic ducts, vasculature, and β-cells. In adult pancreas, CTGF is expressed only in the vasculature. Here we show that pregnant mice with global Ctgf haploinsufficiency (CtgfLacZ/+) have an impairment in maternal β-cell proliferation; no difference was observed in virgin CtgfLacZ/+ females. Using a conditional CTGF allele, we found that mice with a specific inactivation of CTGF in endocrine cells (CtgfΔEndo) develop gestational diabetes during pregnancy, but this is due to a reduction in glucose-stimulated insulin secretion rather than impaired maternal β-cell proliferation. Moreover, virgin CtgfΔEndo females also display impaired GSIS with glucose intolerance, indicating that underlying β-cell dysfunction precedes the development of gestational diabetes in this animal model. This is the first time a role for CTGF in β-cell function has been reported.

scholarly journals AKAP79/150 coordinates leptin-induced PKA activation to regulate KATP channel trafficking in pancreatic β-cells

2020 ◽  
Author(s):  
Veronica A. Cochrane ◽  
Zhongying Yang ◽  
Mark Dell’Acqua ◽  
Show-Ling Shyng
Keyword(s):  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Signaling Mechanism ◽  
Channel Trafficking ◽  
Protein Phosphatase 2B ◽  
Anchoring Protein ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion

AbstractThe adipocyte hormone leptin regulates glucose homeostasis both centrally and peripherally. A key peripheral target is the pancreatic β-cell, which secretes insulin upon glucose stimulation. Leptin suppresses glucose-stimulated insulin secretion by promoting trafficking of KATP channels to the β-cell surface, which increases K+ conductance and causes β-cell hyperpolarization. Here we investigate the signaling mechanism underlying leptin-induced KATP channel translocation with a focus on protein kinase A (PKA). Using FRET-based PKA activity reporters, we show that leptin increases PKA activity at the cell membrane via a signaling pathway involving NMDA receptors, CaMKKβ and AMPK. Genetic knockdown and rescue experiments reveal that leptin activation of PKA requires tethering of PKA to the membrane-targeted PKA-anchoring protein AKAP79/150. Interestingly, disrupting protein phosphatase 2B (PP2B) anchoring to AKAP79/150, known to elevate basal PKA signaling, increases surface KATP channels. Our findings uncover a novel role of AKAP79/150 in coordinating leptin and PKA signaling to regulate β-cell function.

scholarly journals H3K4 Methylation in β-cells Prevents Transcriptional Downregulation and Variance Associated with Type 2 Diabetes

2021 ◽  
Author(s):  
Ben Vanderkruk ◽  
Nina Maeshima ◽  
Daniel J Pasula ◽  
Meilin An ◽  
Priya Suresh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Type 2 Diabetes ◽  
Cell Function ◽  
H3k4 Methylation ◽  
Β Cells ◽  
Β Cell ◽  
Genetic Mouse Model ◽  
Expression Of Genes ◽  
Β Cell Function

SummaryHistone 3 lysine 4 trimethylation (H3K4me3) is associated with promoters of actively expressed genes, with genes important for cell identity frequently having exceptionally broad H3K4me3-enriched domains at their TSS. While H3K4 methylation is implicated in contributing to transcription, maintaining transcriptional stability, facilitating enhancer-promoter interactions, and preventing irreversible silencing, some studies suggest it has little functional impact. Therefore, the function of H3K4 methylation is not resolved. Insufficient insulin release by β-cells is the primary etiology in type 2 diabetes (T2D) and is associated with the loss of expression of genes essential to normal β-cell function. We find that H3K4me3 is reduced in islets from mouse models of diabetes and from human donors with T2D. Using a genetic mouse model to impair H3K4 methyltransferase activity of TrxG complexes, we find that reduction of H3K4 methylation significantly reduces insulin production and glucose-responsiveness and increases transcriptional entropy, indicative of a loss of β-cell maturity. Genes that are downregulated by reduction to H3K4 methylation are concordantly downregulated in T2D. Loss of H3K4 methylation causes global dilution of epigenetic complexity but does not generally reduce gene expression – instead, genes related to β-cell function and/or in particular chromatin environments are specifically affected. While neither H3K4me3 nor H3K4me1 are strictly required for the expression of many genes, the expression of genes with critical roles in β-cell function becomes destabilized, with increased variance and decreased overall expression. Our data further suggests that, in absence of H3K4me3, promoter-associated H3K4me1 is sufficient to maintain expression. Together, these data implicate H3K4 methylation dysregulation as destabilizing β-cell gene expression and contributing to β-cell dysfunction in T2D.

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