scholarly journals Stable overexpression of the glucose-6-phosphatase catalytic subunit attenuates glucose sensitivity of insulin secretion from a mouse pancreatic beta-cell line

2000 ◽  
Vol 164 (3) ◽  
pp. 307-314 ◽  
Author(s):  
K Iizuka ◽  
H Nakajima ◽  
A Ono ◽  
K Okita ◽  
J Miyazaki ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Cell Line ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Glucose Sensor ◽  
Pancreatic Beta Cell ◽  
Catalytic Subunit ◽  
Beta Cell Line ◽  
Glucose Stimulated Insulin Secretion

Glucose-6-phosphatase (G-6-Pase) hydrolyzes glucose-6-phosphate to glucose, reciprocal with the so-called glucose sensor, glucokinase, in pancreatic beta cells. To study the role of G-6-Pase in glucose-stimulated insulin secretion from beta cells, we have introduced rat G-6-Pase catalytic subunit cDNA and have established permanent clones with 3-, 7- and 24-fold G-6-Pase activity of the mouse beta-cell line, MIN6. In these clones, glucose usage and ATP production in the presence of 5.5 or 25 mM glucose were reduced, and glucose-stimulated insulin secretion was decreased in proportion to the increased G-6-Pase activity. In addition, insulin secretory capacity in response to d-fructose and pyruvate was unchanged; however, 25 mM glucose-stimulated insulin secretion and intracellular calcium response were completely inhibited. In the clone with 24-fold G-6-Pase activity, changes in intracellular NAD(P)H autofluorescence in response to 25 mM glucose were reduced, but the changes with 20 mM fructose and 20 mM pyruvate were not altered. Stable overexpression of G-6-Pase in beta cells resulted in attenuation of the overall glucose-stimulated metabolic responses corresponding to the degree of overexpression. This particular experimental manipulation shows that the possibility exists of modulating glucose-stimulated insulin release by thoroughly altering glucose cycling at the glucokinase/G-6-Pase step.

scholarly journals High dose of histone deacetylase inhibitors affects insulin secretory mechanism of pancreatic beta cell line

2018 ◽  
Vol 52 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Eiji Yamato
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Cell Line ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
High Dose ◽  
Min6 Cells ◽  
Beta Cell Line ◽  
High Doses

Abstract Objective. Histone deacytylase inhibitors (HDACis) inhibit the deacetylation of the lysine residue of proteins, including histones, and regulate the transcription of a variety of genes. Recently, HDACis have been used clinically as anti-cancer drugs and possible anti-diabetic drugs. Even though HDACis have been proven to protect the cytokine-induced damage of pancreatic beta cells, evidence also shows that high doses of HDACis are cytotoxic. In the present study, we, therefore, investigated the eff ect of HDACis on insulin secretion in a pancreatic beta cell line. Methods. Pancreatic beta cells MIN6 were treated with selected HDACis (trichostatin A, TSA; valproic acid, VPA; and sodium butyrate, NaB) in medium supplemented with 25 mM glucose and 13% heat-inactivated fetal bovine serum (FBS) for indicated time intervals. Protein expression of Pdx1 and Mafa in MIN6 cells was demonstrated by immunohistochemistry and immunocytochemistry, expression of Pdx1 and Mafa genes was measured by quantitative RT-PCR method. Insulin release from MIN6 cells and insulin cell content were estimated by ELISA kit. Superoxide production in MIN6 cells was measured using a Total ROS/Superoxide Detection System. Results. TSA, VPA, and NaB inhibited the expression of Pdx1 and Mafa genes and their products. TSA treatment led to beta cell malfunction, characterized by enhanced insulin secretion at 3 and 9 mM glucose, but impaired insulin secretion at 15 and 25 mM glucose. Th us, TSA induced dysregulation of the insulin secretion mechanism. TSA also enhanced reactive oxygen species production in pancreatic beta cells. Conclusions. Our results showed that HDACis caused failure to suppress insulin secretion at low glucose concentrations and enhance insulin secretion at high glucose concentrations. In other words, when these HDACis are used clinically, high doses of HDACis may cause hypoglycemia in the fasting state and hyperglycemia in the fed state. When using HDACis, physicians should, therefore, be aware of the capacity of these drugs to modulate the insulin secretory capacity of pancreatic beta cells.

scholarly journals Paired box 6 programs essential exocytotic genes in the regulation of glucose-stimulated insulin secretion and glucose homeostasis

2021 ◽  
Vol 13 (600) ◽  
pp. eabb1038
Author(s):  
Wing Yan So ◽  
Wai Nam Liu ◽  
Adrian Kee Keong Teo ◽  
Guy A. Rutter ◽  
Weiping Han
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Pancreatic Islets ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Cell Function ◽  
Pancreatic Beta Cell ◽  
Beta Cell Line ◽  
Pathophysiological Role ◽  
Glucose Stimulated Insulin Secretion

The paired box 6 (PAX6) transcription factor is crucial for normal pancreatic islet development and function. Heterozygous mutations of PAX6 are associated with impaired insulin secretion and early-onset diabetes mellitus in humans. However, the molecular mechanism of PAX6 in controlling insulin secretion in human beta cells and its pathophysiological role in type 2 diabetes (T2D) remain ambiguous. We investigated the molecular pathway of PAX6 in the regulation of insulin secretion and the potential therapeutic value of PAX6 in T2D by using human pancreatic beta cell line EndoC-βH1, the db/db mouse model, and primary human pancreatic islets. Through loss- and gain-of-function approaches, we uncovered a mechanism by which PAX6 modulates glucose-stimulated insulin secretion (GSIS) through a cAMP response element–binding protein (CREB)/Munc18-1/2 pathway. Moreover, under diabetic conditions, beta cells and pancreatic islets displayed dampened PAX6/CREB/Munc18-1/2 pathway activity and impaired GSIS, which were reversed by PAX6 replenishment. Adeno-associated virus–mediated PAX6 overexpression in db/db mouse pancreatic beta cells led to a sustained amelioration of glycemic perturbation in vivo but did not affect insulin resistance. Our study highlights the pathophysiological role of PAX6 in T2D-associated beta cell dysfunction in humans and suggests the potential of PAX6 gene transfer in preserving and restoring beta cell function.

scholarly journals Mitochondrial DNA Is Required for Regulation of Glucose-stimulated Insulin Secretion in a Mouse Pancreatic Beta Cell Line, MIN6

1996 ◽  
Vol 271 (42) ◽  
pp. 26194-26199 ◽  
Author(s):  
Aki Soejima ◽  
Kimiko Inoue ◽  
Daisaku Takai ◽  
Motohisa Kaneko ◽  
Hisamitsu Ishihara ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Insulin Secretion ◽  
Beta Cell ◽  
Cell Line ◽  
Pancreatic Beta Cell ◽  
Beta Cell Line ◽  
Glucose Stimulated Insulin Secretion

scholarly journals PCSK9 affects expression of key surface proteins in human pancreatic beta cells through intra- and extracellular regulatory circuits

2021 ◽  
Author(s):  
kevin Saitoski ◽  
Maria Ryaboshapkina ◽  
Ghaith Hamza ◽  
Andrew F Jarnuczak ◽  
claire berthault ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Beta Cell ◽  
Pancreatic Islets ◽  
Cell Line ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
Loss Of Function ◽  
Beta Cell Line ◽  
Gain And Loss

Aims/hypothesis: Proprotein convertase subtilisin/kexin 9 (PCSK9) is involved in the degradation of LDLR. However, PCSK9 can target other proteins in a cell-type specific manner. While PCSK9 has been detected in pancreatic islets, its expression in insulin-producing pancreatic beta cells is debated. Herein, we studied PCSK9 expression, regulation and function in the human pancreatic beta cell line EndoC-βH1. Methods: We assessed PCSK9 expression in mouse and human pancreatic islets, and in the pancreatic beta cell line EndoC-βH1. We also studied PCSK9 regulation by cholesterol, lipoproteins, Mevastatin, and by SREBPs transcription factors. To evaluate PCSK9 function in pancreatic beta cells, we performed PCSK9 gain-and loss-of-function experiments in EndoC-βH1 using siPCSK9 or recombinant PCSK9 treatments, respectively. Results: We demonstrate that PCSK9 is expressed and secreted by pancreatic beta cells. In EndoC-βH1 cells, PCSK9 expression is regulated by cholesterol and by SREBPs transcription factors. Importantly, PCSK9 knockdown results in multiple transcriptome, proteome and secretome deregulations and impaired insulin secretion. By gain- and loss-of- function experiments, we observed that PCSK9 regulates the expression levels of LDLR and VLDLR through an extracellular mechanism while CD36, PD-L1 and HLA-ABC are regulated through an intracellular mechanism. Conclusions/interpretation: Collectively, these results highlight PCSK9 as an important regulator of CD36, PD-L1 and HLA-ABC cell surface expression in pancreatic beta cells. Data availability: RNA-seq data have been deposited to GEO database with accession number GSE182016. Mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the following identifiers: PXD027921, PXD027911 and PXD027913.

scholarly journals Sfrp5 increases glucose-stimulated insulin secretion in the rat pancreatic beta cell line INS-1E

PLoS ONE ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. e0213650 ◽  
Author(s):  
Maren Carstensen-Kirberg ◽  
Karin Röhrig ◽  
Corinna Niersmann ◽  
D. Margriet Ouwens ◽  
Bengt F. Belgardt ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Cell Line ◽  
Pancreatic Beta Cell ◽  
Beta Cell Line ◽  
Glucose Stimulated Insulin Secretion

scholarly journals Tankyrase interacts with the allosteric site of glucokinase and inhibits its glucose-sensing function in the beta cell

2021 ◽  
Author(s):  
Nai-Wen Chi ◽  
Travis Eisemann ◽  
Tsung-Yin J Yeh ◽  
Swati Roy ◽  
Tyler J Chi ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Glucose Sensor ◽  
Pancreatic Beta Cell ◽  
Glucose Sensing ◽  
Binding Motif ◽  
Allosteric Site

Insulin secretion in the pancreatic beta cell is rate-limited by glucokinase (GCK), the glucose sensor that catalyzes the first step of glucose metabolism. GCK consists of two lobes connected by a flexible hinge that allows the kinase to sample a spectrum of conformations ranging from the active, closed form to several inactive, less-compact forms. Activating GCK mutations can cause hyperinsulinemia and hypoglycemia in infants. A similar phenotype is exhibited in mice deficient in tankyrase (TNKS), prompting us to investigate whether TNKS might modulate the glucose-sensing function of GCK. We found that TNKS colocalizes and directly interacts with GCK. Their interaction is mediated by two ankyrin-repeat clusters (ARC-2 and -5) in TNKS and a tankyrase-binding motif (TBM, aa 63-68) in the GCK hinge. This interaction is conformation sensitive: human GCK variants that cause hyperglycemia (V62M) or hypoglycemia (S64Y) enhance or diminish the interaction respectively, even though they have no impact on TNKS interaction in the context of a GCK peptide (V62M) or a peptide library (S64Y). Moreover, the TNKS-GCK interaction is inhibited by high concentrations of glucose, which are known to stabilize GCK in the active (closed, glucose-avid) conformation. Conversely, glucose phosphorylation by GCK in vitro is inhibited by TNKS. To validate this in vitro inhibitory effect in the MIN6 beta cells, we showed that glucose-stimulated insulin secretion is suppressed upon stabilization of the TNKS protein and conversely is enhanced upon TNKS knockdown. Based on these findings as well as by contrasting with hexokinase-2, we propose that TNKS is a physiological GCK inhibitor in pancreatic beta cells that acts by trapping the kinase in an open (inactive) conformation.

scholarly journals Effects of High Glucose Levels and Glycated Serum on GIP Responsiveness in the Pancreatic Beta Cell Line HIT-T15

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Alessandra Puddu ◽  
Roberta Sanguineti ◽  
Fabrizio Montecucco ◽  
Giorgio Luciano Viviani
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Cell Line ◽  
High Glucose ◽  
Intracellular Signaling ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
Diabetic Patients ◽  
Glucose Levels ◽  
Beta Cell Line

Glucose-dependent insulinotropic peptide (GIP) is an incretin hormone produced in the gastrointestinal tract that stimulates glucose dependent insulin secretion. Impaired incretin response has been documented in diabetic patients and was mainly related to the inability of the pancreatic beta cells to secrete insulin in response to GIP. Advanced Glycation End Products (AGEs) have been shown to play an important role in pancreatic beta cell dysfunction. The aim of this study is to investigate whether the exposure to AGEs can induce GIP resistance in the pancreatic beta cell line HIT-T15. Cells were cultured for 5 days in low (CTR) or high glucose (HG) concentration in the presence of AGEs (GS) to evaluate the expression of GIP receptor (GIPR), the intracellular signaling activated by GIP, and secretion of insulin in response to GIP. The results showed that incubation with GS alone altered intracellular GIP signaling and decreased insulin secretion as compared to CTR. GS in combination with HG reduced the expression of GIPR and PI3K and abrogated GIP-induced AKT phosphorylation and GIP-stimulated insulin secretion. In conclusion, we showed that treatment with GS is associated with the loss of the insulinotropic effect of GIP in hyperglycemic conditions.

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