Carbon monoxide enhances calcium transients and glucose-stimulated insulin secretion from pancreatic β-cells by activating Phospholipase C signal pathway in diabetic mice

2021 ◽  
Author(s):  
Shenghui Liang ◽  
Jia Zhao ◽  
Quanyi Wang ◽  
Min Yang ◽  
Xiaozhi Wang ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Insulin Secretion ◽  
Phospholipase C ◽  
Signal Pathway ◽  
Calcium Transients ◽  
Diabetic Mice ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Glucose Stimulated Insulin Secretion

scholarly journals γ-Oryzanol Protects Pancreatic β-Cells Against Endoplasmic Reticulum Stress in Male Mice

Endocrinology ◽  
2015 ◽  
Vol 156 (4) ◽  
pp. 1242-1250 ◽  
Author(s):  
Chisayo Kozuka ◽  
Sumito Sunagawa ◽  
Rei Ueda ◽  
Moritake Higa ◽  
Hideaki Tanaka ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Insulin Secretion ◽  
Er Stress ◽  
High Fat Diet ◽  
Diabetic Mice ◽  
High Fat ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Glucose Stimulated Insulin Secretion

Abstract Endoplasmic reticulum (ER) stress is profoundly involved in dysfunction of β-cells under high-fat diet and hyperglycemia. Our recent study in mice showed that γ-oryzanol, a unique component of brown rice, acts as a chemical chaperone in the hypothalamus and improves feeding behavior and diet-induced dysmetabolism. However, the entire mechanism whereby γ-oryzanol improves glucose metabolism throughout the body still remains unclear. In this context, we tested whether γ-oryzanol reduces ER stress and improves function and survival of pancreatic β-cells using murine β-cell line MIN6. In MIN6 cells with augmented ER stress by tunicamycin, γ-oryzanol decreased exaggerated expression of ER stress-related genes and phosphorylation of eukaryotic initiation factor-2α, resulting in restoration of glucose-stimulated insulin secretion and prevention of apoptosis. In islets from high-fat diet-fed diabetic mice, oral administration of γ-oryzanol improved glucose-stimulated insulin secretion on following reduction of exaggerated ER stress and apoptosis. Furthermore, we examined the impact of γ-oryzanol on low-dose streptozotocin-induced diabetic mice, where exaggerated ER stress and resultant apoptosis in β-cells were observed. Also in this model, γ-oryzanol attenuated mRNA level of genes involved in ER stress and apoptotic signaling in islets, leading to amelioration of glucose dysmetabolism. Taken together, our findings demonstrate that γ-oryzanol directly ameliorates ER stress-induced β-cell dysfunction and subsequent apoptosis, highlighting usefulness of γ-oryzanol for the treatment of diabetes mellitus.

scholarly journals Brain-selective Kinase 2 (BRSK2) Phosphorylation on PCTAIRE1 Negatively Regulates Glucose-stimulated Insulin Secretion in Pancreatic β-Cells

2012 ◽  
Vol 287 (36) ◽  
pp. 30368-30375 ◽  
Author(s):  
Xin-Ya Chen ◽  
Xiu-Ting Gu ◽  
Hexige Saiyin ◽  
Bo Wan ◽  
Yu-Jing Zhang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Glucose Stimulated Insulin Secretion

scholarly journals Peroxisome Proliferator-Activated Receptor α (PPARα) Potentiates, whereas PPARγ Attenuates, Glucose-Stimulated Insulin Secretion in Pancreatic β-Cells

Endocrinology ◽  
2005 ◽  
Vol 146 (8) ◽  
pp. 3266-3276 ◽  
Author(s):  
Kim Ravnskjaer ◽  
Michael Boergesen ◽  
Blanca Rubi ◽  
Jan K. Larsen ◽  
Tina Nielsen ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Mitochondrial Membrane ◽  
Uncoupling Protein ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Peroxisome Proliferator Activated Receptor ◽  
Glucose Stimulated Insulin Secretion

Abstract Fatty acids (FAs) are known to be important regulators of insulin secretion from pancreatic β-cells. FA-coenzyme A esters have been shown to directly stimulate the secretion process, whereas long-term exposure of β-cells to FAs compromises glucose-stimulated insulin secretion (GSIS) by mechanisms unknown to date. It has been speculated that some of these long-term effects are mediated by members of the peroxisome proliferator-activated receptor (PPAR) family via an induction of uncoupling protein-2 (UCP2). In this study we show that adenoviral coexpression of PPARα and retinoid X receptor α (RXRα) in INS-1E β-cells synergistically and in a dose- and ligand-dependent manner increases the expression of known PPARα target genes and enhances FA uptake and β-oxidation. In contrast, ectopic expression of PPARγ/RXRα increases FA uptake and deposition as triacylglycerides. Although the expression of PPARα/RXRα leads to the induction of UCP2 mRNA and protein, this is not accompanied by reduced hyperpolarization of the mitochondrial membrane, indicating that under these conditions, increased UCP2 expression is insufficient for dissipation of the mitochondrial proton gradient. Importantly, whereas expression of PPARγ/RXRα attenuates GSIS, the expression of PPARα/RXRα potentiates GSIS in rat islets and INS-1E cells without affecting the mitochondrial membrane potential. These results show a strong subtype specificity of the two PPAR subtypes α and γ on lipid partitioning and insulin secretion when systematically compared in a β-cell context.

Tolbutamide and diazoxide modulate phospholipase C-linked Ca2+ signaling and insulin secretion in β-cells

2000 ◽  
Vol 278 (4) ◽  
pp. E639-E647 ◽  
Author(s):  
Christof Schöfl ◽  
Julia Börger ◽  
Thilo Mader ◽  
Mark Waring ◽  
Alexander von zur Mühlen ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Phospholipase C ◽  
Insulin Release ◽  
Arginine Vasopressin ◽  
Bay K 8644 ◽  
Free Medium ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Activating Receptors

Arginine vasopressin (AVP), bombesin, and ACh increase cytosolic free Ca2+ and potentiate glucose-induced insulin release by activating receptors linked to phospholipase C (PLC). We examined whether tolbutamide and diazoxide, which close or open ATP-sensitive K+ channels (KATP channels), respectively, interact with PLC-linked Ca2+ signals in HIT-T15 and mouse β-cells and with PLC-linked insulin secretion from HIT-T15 cells. In the presence of glucose, the PLC-linked Ca2+ signals were enhanced by tolbutamide (3–300 μM) and inhibited by diazoxide (10–100 μM). The effects of tolbutamide and diazoxide on PLC-linked Ca2+ signaling were mimicked by BAY K 8644 and nifedipine, an activator and inhibitor of L-type voltage-sensitive Ca2+channels, respectively. Neither tolbutamide nor diazoxide affected PLC-linked mobilization of internal Ca2+ or store-operated Ca2+ influx through non-L-type Ca2+ channels. In the absence of glucose, PLC-linked Ca2+ signals were diminished or abolished; this effect could be partly antagonized by tolbutamide. In the presence of glucose, tolbutamide potentiated and diazoxide inhibited AVP- or bombesin-induced insulin secretion from HIT-T15 cells. Nifedipine (10 μM) blocked both the potentiating and inhibitory actions of tolbutamide and diazoxide on AVP-induced insulin release, respectively. In glucose-free medium, AVP-induced insulin release was reduced but was again potentiated by tolbutamide, whereas diazoxide caused no further inhibition. Thus tolbutamide and diazoxide regulate both PLC-linked Ca2+signaling and insulin secretion from pancreatic β-cells by modulating KATP channels, thereby determining voltage-sensitive Ca2+ influx.

scholarly journals L-Arginine prevents cereblon-mediated ubiquitination of glucokinase and stimulates glucose-6-phosphate production in pancreatic β-cells

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Jaeyong Cho ◽  
Yukio Horikawa ◽  
Mayumi Enya ◽  
Jun Takeda ◽  
Yoichi Imai ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Direct Stimulation ◽  
Glucose Ratio ◽  
Glucose Stimulated Insulin Secretion

Abstract We sought to determine a mechanism by which L-arginine increases glucose-stimulated insulin secretion (GSIS) in β-cells by finding a protein with affinity to L-arginine using arginine-immobilized magnetic nanobeads technology. Glucokinase (GCK), the key regulator of GSIS and a disease-causing gene of maturity-onset diabetes of the young type 2 (MODY2), was found to bind L-arginine. L-Arginine stimulated production of glucose-6-phosphate (G6P) and induced insulin secretion. We analyzed glucokinase mutants and identified three glutamate residues that mediate binding to L-arginine. One MODY2 patient with GCKE442* demonstrated lower C-peptide-to-glucose ratio after arginine administration. In β-cell line, GCKE442* reduced L-arginine-induced insulin secretion compared with GCKWT. In addition, we elucidated that the binding of arginine protects glucokinase from degradation by E3 ubiquitin ligase cereblon mediated ubiquitination. We conclude that L-arginine induces insulin secretion by increasing G6P production by glucokinase through direct stimulation and by prevention of degradation.

scholarly journals The adaptor protein APPL2 controls glucose-stimulated insulin secretion via F-actin remodeling in pancreatic β-cells

2020 ◽  
Vol 117 (45) ◽  
pp. 28307-28315
Author(s):  
Baile Wang ◽  
Huige Lin ◽  
Xiaomu Li ◽  
Wenqi Lu ◽  
Jae Bum Kim ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Adaptor Protein ◽  
Hek293 Cells ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Actin Remodeling ◽  
Actin Depolymerization ◽  
Glucose Stimulated Insulin Secretion

Filamentous actin (F-actin) cytoskeletal remodeling is critical for glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells, and its dysregulation causes type 2 diabetes. The adaptor protein APPL1 promotes first-phase GSIS by up-regulating solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein expression. However, whether APPL2 (a close homology of APPL1 with the same domain organization) plays a role in β-cell functions is unknown. Here, we show that APPL2 enhances GSIS by promoting F-actin remodeling via the small GTPase Rac1 in pancreatic β-cells. β-cell specific abrogation of APPL2 impaired GSIS, leading to glucose intolerance in mice. APPL2 deficiency largely abolished glucose-induced first- and second-phase insulin secretion in pancreatic islets. Real-time live-cell imaging and phalloidin staining revealed that APPL2 deficiency abolished glucose-induced F-actin depolymerization in pancreatic islets. Likewise, knockdown of APPL2 expression impaired glucose-stimulated F-actin depolymerization and subsequent insulin secretion in INS-1E cells, which were attributable to the impairment of Ras-related C3 botulinum toxin substrate 1 (Rac1) activation. Treatment with the F-actin depolymerization chemical compounds or overexpression of gelsolin (a F-actin remodeling protein) rescued APPL2 deficiency-induced defective GSIS. In addition, APPL2 interacted with Rac GTPase activating protein 1 (RacGAP1) in a glucose-dependent manner via the bin/amphiphysin/rvs-pleckstrin homology (BAR-PH) domain of APPL2 in INS-1E cells and HEK293 cells. Concomitant knockdown of RacGAP1 expression reverted APPL2 deficiency-induced defective GSIS, F-actin remodeling, and Rac1 activation in INS-1E cells. Our data indicate that APPL2 interacts with RacGAP1 and suppresses its negative action on Rac1 activity and F-actin depolymerization thereby enhancing GSIS in pancreatic β-cells.

scholarly journals Neuroligin-2-derived peptide-covered polyamidoamine-based (PAMAM) dendrimers enhance pancreatic β-cells' proliferation and functions

MedChemComm ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 280-293
Author(s):  
Anna Munder ◽  
Yoni Moskovitz ◽  
Aviv Meir ◽  
Shirin Kahremany ◽  
Laura Levy ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cellular Stress ◽  
Pamam Dendrimers ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Cell Functions ◽  
Functional Maturation ◽  
Glucose Stimulated Insulin Secretion

The nanoscale composite improved β-cell functions in terms of rate of proliferation, glucose-stimulated insulin secretion, resistance to cellular stress and functional maturation.

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