scholarly journals FoxO1 Deacetylation Decreases Fatty Acid Oxidation in β-Cells and Sustains Insulin Secretion in Diabetes

2016 ◽  
Vol 291 (19) ◽  
pp. 10162-10172 ◽  
Author(s):  
Ja Young Kim-Muller ◽  
Young Jung R. Kim ◽  
Jason Fan ◽  
Shangang Zhao ◽  
Alexander S. Banks ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Acid Oxidation ◽  
Β Cells

scholarly journals Adenovirus-mediated overexpression of liver carnitine palmitoyltransferase I in INS1E cells: effects on cell metabolism and insulin secretion

2002 ◽  
Vol 364 (1) ◽  
pp. 219-226 ◽  
Author(s):  
Blanca RUBÍ ◽  
Peter A. ANTINOZZI ◽  
Laura HERRERO ◽  
Hisamitsu ISHIHARA ◽  
Guillermina ASINS ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Insulin Secretion ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Fold Increase ◽  
Acid Oxidation ◽  
Β Cells ◽  
Β Cell ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I

Lipid metabolism in the β-cell is critical for the regulation of insulin secretion. Pancreatic β-cells chronically exposed to fatty acids show higher carnitine palmitoyltransferase I (CPT I) protein levels, higher palmitate oxidation rates and an altered insulin response to glucose. We examined the effect of increasing CPT I levels on insulin secretion in cultured β-cells. We prepared a recombinant adenovirus containing the cDNA for the rat liver isoform of CPT I. The overexpression of CPT I in INS1E cells caused a more than a 5-fold increase in the levels of CPT I protein (detected by Western blotting), a 6-fold increase in the CPT activity, and an increase in fatty acid oxidation at 2.5mM glucose (1.7-fold) and 15mM glucose (3.1-fold). Insulin secretion was stimulated in control cells by 15mM glucose or 30mM KCl. INS1E cells overexpressing CPT I showed lower insulin secretion on stimulation with 15mM glucose (−40%; P<0.05). This decrease depended on CPT I activity, since the presence of etomoxir, a specific inhibitor of CPT I, in the preincubation medium normalized the CPT I activity, the fatty-acid oxidation rate and the insulin secretion in response to glucose. Exogenous palmitate (0.25mM) rescued glucose-stimulated insulin secretion (GSIS) in CPT I-overexpressing cells, indicating that the mechanism of impaired GSIS was through the depletion of a critical lipid. Depolarizing the cells with KCl or intermediary glucose concentrations (7.5mM) elicited similar insulin secretion in control cells and cells overexpressing CPT I. Glucose-induced ATP increase, glucose metabolism and the triacylglycerol content remained unchanged. These results provide further evidence that CPT I activity regulates insulin secretion in the β-cell. They also indicate that up-regulation of CPT I contributes to the loss of response to high glucose in β-cells exposed to fatty acids.

Short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency associated with hyperinsulinism: a novel glucose–fatty acid cycle?

2003 ◽  
Vol 31 (6) ◽  
pp. 1137-1139 ◽  
Author(s):  
S. Eaton ◽  
I. Chatziandreou ◽  
S. Krywawych ◽  
S. Pen ◽  
P.T. Clayton ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Dehydrogenase Deficiency ◽  
Short Chain ◽  
Acid Oxidation ◽  
Β Cells ◽  
Molecular Defects ◽  
Glucose Fatty Acid Cycle ◽  
Hydroxyacyl Coa Dehydrogenase

Hyperinsulinism of infancy is caused by inappropriate insulin secretion in pancreatic β-cells, even when blood glucose is low. Several molecular defects are known to cause hyperinsulinism of infancy, such as KATP channelopathies and regulatory defects of glucokinase and glutamate dehydrogenase. Although defects of fatty acid oxidation have not previously been known to cause hyperinsulinism, patients with deficiency in SCHAD (short-chain 3-hydroxyacyl-CoA dehydrogenase; an enzyme of mitochondrial β-oxidation) have hyperinsulinism. A novel link between fatty acid oxidation and insulin secretion may explain hyperinsulinism in these patients.

scholarly journals Pancreatic Islet Adaptation to Fasting Is Dependent on Peroxisome Proliferator-Activated Receptor α Transcriptional Up-Regulation of Fatty Acid Oxidation

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 375-382 ◽  
Author(s):  
Sandrine Gremlich ◽  
Christopher Nolan ◽  
Raphaël Roduit ◽  
Rémy Burcelin ◽  
Marie-Line Peyot ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Pancreatic Islet ◽  
Cellular Response ◽  
Uncoupling Protein ◽  
Acid Oxidation ◽  
Hyperinsulinemic Hypoglycemia ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

The cellular response to fasting and starvation in tissues such as heart, skeletal muscle, and liver requires peroxisome proliferator-activated receptor-α (PPARα)-dependent up-regulation of energy metabolism toward fatty acid oxidation (FAO). PPARα null (PPARαKO) mice develop hyperinsulinemic hypoglycemia in the fasting state, and we previously showed that PPARα expression is increased in islets at low glucose. On this basis, we hypothesized that enhanced PPARα expression and FAO, via depletion of lipid-signaling molecule(s) for insulin exocytosis, are also involved in the normal adaptive response of the islet to fasting. Fasted PPARαKO mice compared with wild-type mice had supranormal ip glucose tolerance due to increased plasma insulin levels. Isolated islets from the PPARα null mice had a 44% reduction in FAO, normal glucose use and oxidation, and enhanced glucose-induced insulin secretion. In normal rats, fasting for 24 h increased islet PPARα, carnitine palmitoyltransferase 1, and uncoupling protein-2 mRNA expression by 60%, 62%, and 82%, respectively. The data are consistent with the view that PPARα, via transcriptionally up-regulating islet FAO, can reduce insulin secretion, and that this mechanism is involved in the normal physiological response of the pancreatic islet to fasting such that hypoglycemia is avoided.

Circulating lipids are lowered but pancreatic islet lipid metabolism and insulin secretion are unaltered in exercise-trained female rats

2007 ◽  
Vol 32 (2) ◽  
pp. 241-248 ◽  
Author(s):  
Julien Lamontagne ◽  
Pellegrino Masiello ◽  
Mariannick Marcil ◽  
Viviane Delghingaro-Augusto ◽  
Yan Burelle ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Insulin Secretion ◽  
Fatty Acid ◽  
Lipid Metabolism ◽  
Free Fatty Acids ◽  
Fatty Acid Oxidation ◽  
Female Rats ◽  
Acid Oxidation ◽  
Β Cell ◽  
Glucose Stimulated Insulin Secretion

Deteriorating islet β-cell function is key in the progression of an impaired glucose tolerance state to overt type 2 diabetes (T2D), a transition that can be delayed by exercise. We have previously shown that trained rats are protected from heart ischemia–reperfusion injury in correlation with an increase in cardiac tissue fatty-acid oxidation. This trained metabolic phenotype, if induced in the islet, could also prevent β-cell failure in the pathogenesis of T2D. To assess the effect of training on islet lipid metabolism and insulin secretion, female Sprague–Dawley rats were exercised on a treadmill for 90 min/d, 4 d/week, for 10 weeks. Islet fatty-acid oxidation, the expression of key lipid metabolism genes, and glucose-stimulated insulin secretion were determined in freshly isolated islets from trained and sedentary control rats after a 48 h rest period from the last exercise. Although this moderate training reduced plasma glycerol, free fatty acids, and triglyceride levels by about 40%, consistent with reduced lipolysis from adipose tissue, it did not alter islet fatty-acid oxidation, nor the islet expression of key transcription factors and enzymes of lipid metabolism. The training also had no effect on glucose-stimulated insulin secretion or its amplification by free fatty acids. In summary, chronic exercise training did not cause an intrinsic change in islet lipid metabolism. Training did, however, substantially reduce the exposure of islets to exogenous lipid, thereby providing a potential mechanism by which exercise can prevent islet β-cell failure leading to T2D.

scholarly journals Glucose-induced repression of PPARα gene expression in pancreatic β-cells involves PP2A activation and AMPK inactivation

2006 ◽  
Vol 36 (2) ◽  
pp. 289-299 ◽  
Author(s):  
Kim Ravnskjaer ◽  
Michael Boergesen ◽  
Louise T Dalgaard ◽  
Susanne Mandrup
Keyword(s):  
Gene Expression ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Protein Phosphatase ◽  
Glucose Repression ◽  
Acid Oxidation ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Phosphatase 2A

Tight regulation of fatty acid metabolism in pancreatic β-cells is important for β-cell viability and function. Chronic exposure to elevated concentrations of fatty acid is associated with β-cell lipotoxicity. Glucose is known to repress fatty acid oxidation and hence to augment the toxicity of fatty acids. The peroxisome proliferator activated receptor α (PPARα) is a key activator of genes involved in β-cell fatty acid oxidation, and transcription of the PPARα gene has been shown to be repressed by increasing concentrations of glucose in β-cells. However, the mechanism underlying this transcriptional repression by glucose remains unclear. Here we report that glucose-induced repression of PPARα gene expression in INS-1E cells is independent of β-cell excitation and insulin secretion but requires activation of protein phosphatase 2A in a process involving inactivation of the AMP-activated protein kinase (AMPK). Pharmacological activation of AMPK at high glucose concentrations interferes with glucose repression of PPARα and PPARα target genes in INS-1E cells as well as in rat islets. Specific knock-down of the catalytic AMPK-subunit AMPKα2 but not AMPKα1 using RNAi suppressed PPARα expression, thereby mimicking the effect of glucose. These results indicate that activation of protein phosphatase 2A and subsequent inactivation of AMPK is necessary for glucose repression of PPARα expression in pancreatic β-cells.

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