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Sodium channel beta1 regulatory subunit deficiency reduces pancreatic islet glucose-stimulated insulin and glucagon secretion.

ABSTRACT: Glucose-stimulated insulin and glucagon release regulates glucose homeostasis by an excitation-secretion coupling pathway beginning with ATP-sensitive K(+) channel closure, membrane depolarization, and entry of calcium ions to stimulate exocytosis. The contribution of voltage-gated sodium channels to this release pathway is still being elucidated. We demonstrate that loss of Scn1b, a major regulatory subunit expressed with Na(v)1.7 protein in mouse pancreatic islets, reduces glucose-stimulated insulin and glucagon secretion in vitro and in vivo, resulting in severe fed and fasting hypoglycemia. This genetic mouse model is the first to demonstrate that sodium channelopathy impairs the physiological excitation-release coupling pathway for pancreatic insulin and glucagon release.

SUBMITTER: Ernst SJ

PROVIDER: S-EPMC2654754 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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Sodium channel beta1 regulatory subunit deficiency reduces pancreatic islet glucose-stimulated insulin and glucagon secretion.

Ernst Sara J SJ Aguilar-Bryan Lydia L Noebels Jeffrey L JL

Endocrinology 20081106 3

Glucose-stimulated insulin and glucagon release regulates glucose homeostasis by an excitation-secretion coupling pathway beginning with ATP-sensitive K(+) channel closure, membrane depolarization, and entry of calcium ions to stimulate exocytosis. The contribution of voltage-gated sodium channels to this release pathway is still being elucidated. We demonstrate that loss of Scn1b, a major regulatory subunit expressed with Na(v)1.7 protein in mouse pancreatic islets, reduces glucose-stimulated i ...[more]

PMID: 18988673

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Project description:Background and Aims: Inflammasome-mediated caspase-1 activity regulates the maturation and release of the pro-inflammatory cytokines interleukin (IL)-1M-CM-^_ and IL-18. Recently, we showed that caspase-1 deficiency strongly reduces high fat diet-induced adiposity although the mechanism is still unclear. We now aimed to elucidate the mechanism by which caspase-1 deficiency reduces modulates resistance to high fat diet-feeding fat accumulation in adipose tissue by focusing on the role of caspase-1 in the regulation of triglyceride (TG)-rich lipoprotein metabolism. Methods: Caspase-1 deficient and wild-type mice (both C57Bl/6 background) were used to determine postprandial TG kinetics, intestinal TG absorption, VLDL-TG production as well as TG clearance, all of which strongly contribute to the supply of TG for storage in adipose tissue. Micro-array and qPCR analysis were used to unravel intestinal and hepatic metabolic pathways involved. Results: Caspase-1 deficiency reduced the postprandial response to an oral lipid load, while tissue specific clearance of TG-rich lipoproteins was not changed. Indeed, an oral olive oil gavage containing [3H]TG revealed that caspase-1 deficiency significantly decreased intestinal chylomicron-TG production and reduced the uptake of [3H]TG-derived FA by liver, muscle, and adipose tissue. Similarly, caspase-1 deficiency reduced the hepatic VLDL-TG production without reducing VLDL-apoB production, despite an elevated hepatic TG content. Pathway analysis revealed that caspase-1 deficiency reduces intestinal and hepatic expression of genes involved in lipogenesis. Conclusions: Absence of caspase-1 reduces assembly and secretion of TG-rich lipoproteins, thereby reducing the availability of TG-derived FA for uptake by peripheral organs including adipose tissue. We anticipate that caspase-1 represents a novel link between innate immunity and lipid metabolism. Keywords: Expression profiling by array Wild-type (WT) and Casp1-null mice were maintained at lab chow. Animals, aged between 14 and 16 weeks (n=3 per genotype), were killed and liver and intestinal segments were removed. Livers were isolated from mice that were fasted over night, whereas intesines were removed from mice 2 hrs after they received an oral lipid load.Total RNA was isolated and subjected to gene expression profiling.

Dataset Information

Sodium channel beta1 regulatory subunit deficiency reduces pancreatic islet glucose-stimulated insulin and glucagon secretion.

Publications

Sodium channel beta1 regulatory subunit deficiency reduces pancreatic islet glucose-stimulated insulin and glucagon secretion.

Similar Datasets

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