Dataset Information

Glucokinase and IRS-2 are required for compensatory beta cell hyperplasia in response to high-fat diet-induced insulin resistance.

ABSTRACT: Glucokinase (Gck) functions as a glucose sensor for insulin secretion, and in mice fed standard chow, haploinsufficiency of beta cell-specific Gck (Gck(+/-)) causes impaired insulin secretion to glucose, although the animals have a normal beta cell mass. When fed a high-fat (HF) diet, wild-type mice showed marked beta cell hyperplasia, whereas Gck(+/-) mice demonstrated decreased beta cell replication and insufficient beta cell hyperplasia despite showing a similar degree of insulin resistance. DNA chip analysis revealed decreased insulin receptor substrate 2 (Irs2) expression in HF diet-fed Gck(+/-) mouse islets compared with wild-type islets. Western blot analyses confirmed upregulated Irs2 expression in the islets of HF diet-fed wild-type mice compared with those fed standard chow and reduced expression in HF diet-fed Gck(+/-) mice compared with those of HF diet-fed wild-type mice. HF diet-fed Irs2(+/-) mice failed to show a sufficient increase in beta cell mass, and overexpression of Irs2 in beta cells of HF diet-fed Gck(+/-) mice partially prevented diabetes by increasing beta cell mass. These results suggest that Gck and Irs2 are critical requirements for beta cell hyperplasia to occur in response to HF diet-induced insulin resistance.

SUBMITTER: Terauchi Y

PROVIDER: S-EPMC1716196 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

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Glucokinase and IRS-2 are required for compensatory beta cell hyperplasia in response to high-fat diet-induced insulin resistance.

Terauchi Yasuo Y Takamoto Iseki I Kubota Naoto N Matsui Junji J Suzuki Ryo R Komeda Kajuro K Hara Akemi A Toyoda Yukiyasu Y Miwa Ichitomo I Aizawa Shinichi S Tsutsumi Shuichi S Tsubamoto Yoshiharu Y Hashimoto Shinji S Eto Kazuhiro K Nakamura Akinobu A Noda Mitsuhiko M Tobe Kazuyuki K Aburatani Hiroyuki H Nagai Ryozo R Kadowaki Takashi T

The Journal of clinical investigation 20070101 1

Glucokinase (Gck) functions as a glucose sensor for insulin secretion, and in mice fed standard chow, haploinsufficiency of beta cell-specific Gck (Gck(+/-)) causes impaired insulin secretion to glucose, although the animals have a normal beta cell mass. When fed a high-fat (HF) diet, wild-type mice showed marked beta cell hyperplasia, whereas Gck(+/-) mice demonstrated decreased beta cell replication and insufficient beta cell hyperplasia despite showing a similar degree of insulin resistance. ...[more]

PMID: 17200721

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Project description:ObjectiveThe contribution of beta-cell dysfunction to type 2 diabetes (T2D) is not restricted to insulinopenia in the late stages of the disease. Elevated fasting insulinemia in normoglycemic humans is a major factor predicting the onset of insulin resistance and T2D, demonstrating an early alteration of beta-cell function in T2D. Moreover, an early and chronic increase in fasting insulinemia contributes to insulin resistance in high-fat diet (HFD)-fed mice. However, whether there are genetic factors that promote beta-cell-initiated insulin resistance remains undefined. Human variants of the mitochondrial transporter ABCB10, which regulates redox by increasing bilirubin synthesis, have been associated with an elevated risk of T2D. The effects of T2D ABCB10 variants on ABCB10 expression and the actions of ABCB10 in beta-cells are unknown.MethodsThe expression of beta-cell ABCB10 was analyzed in published transcriptome datasets from human beta-cells carrying the T2D-risk ABCB10 variant. Insulin sensitivity, beta-cell proliferation, and secretory function were measured in beta-cell-specific ABCB10 KO mice (Ins1Cre-Abcb10flox/flox). The short-term role of beta-cell ABCB10 activity on glucose-stimulated insulin secretion (GSIS) was determined in isolated islets.ResultsCarrying the T2Drisk allele G of ABCB10 rs348330 variant was associated with increased ABCB10 expression in human beta-cells. Constitutive deletion of Abcb10 in beta-cells protected mice from hyperinsulinemia and insulin resistance by limiting HFD-induced beta-cell expansion. An early limitation in GSIS and H2O2-mediated signaling caused by elevated ABCB10 activity can initiate an over-compensatory expansion of beta-cell mass in response to HFD. Accordingly, increasing ABCB10 expression was sufficient to limit GSIS capacity. In health, ABCB10 protein was decreased during islet maturation, with maturation restricting beta-cell proliferation and elevating GSIS. Finally, ex-vivo and short-term deletion of ABCB10 in islets isolated from HFD-fed mice increased H2O2 and GSIS, which was reversed by bilirubin treatments.ConclusionsBeta-cell ABCB10 is required for HFD to induce insulin resistance in mice by amplifying beta-cell mass expansion to maladaptive levels that cause fasting hyperinsulinemia.

Project description:Recent discovery reveals HFD insult can cause insulin resistance very rapidly, but the underlying mechanism is still not well understood. We performed a short term experiment in a Diet Induced Insulin resistance mouse model. Objective: Insulin resistance (IR) is one of the earliest predictors of type 2 diabetes. However, diagnosis of IR is limited. High fat fed mouse models provide key insights into IR. We hypothesized that early features of IR are associated with persistent changes in gene expression (GE) and endeavoured to (a) develop novel methods for improving signal:noise in analysis of human GE using mouse models; (b) identify a GE motif that accurately diagnoses IR in humans; and (c) identify novel biology associated with IR in humans. Methods: We integrated human muscle GE data with longitudinal mouse GE data and developed an unbiased three-level cross-species analysis platform (single-gene, gene-set and networks) to generate a gene expression motif (GEM) indicative of IR. A logistic regression classification model validated GEM in 3 independent human datasets (n =115). Results: This GEM of 93 genes substantially improved diagnosis of IR compared to routine clinical measures across multiple independent datasets. Individuals misclassified by GEM possessed other metabolic features raising the possibility that they represent a separate metabolic subclass. The GEM was enriched in pathways previously implicated in insulin action and revealed novel associations between Î²-catenin and Jak1 and IR. Functional analyses using small molecule inhibitors showed an important role for these proteins in insulin action. Conclusions: This study shows that systems approaches for identifying molecular signatures provides a powerful way to stratify individuals into discrete metabolic groups. Moreover, we speculate that the Î²-catenin pathway may represent a novel biomarker for IR in humans that warrant future investigation. Comparison of gene expression in muscle tissue during High Fat Diet (HFD) time course (day 5 and day 42). Chow diet will serve as control for HFD. 4 samples per group serve as experimental replicates.

Dataset Information

Glucokinase and IRS-2 are required for compensatory beta cell hyperplasia in response to high-fat diet-induced insulin resistance.

Publications

Glucokinase and IRS-2 are required for compensatory beta cell hyperplasia in response to high-fat diet-induced insulin resistance.

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