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Molecular Endocrinology
Year: 2010  |  Volume: 24  |  Issue: 7  |  Page No.: 1423 - 1433

The Roles of ATF3, an Adaptive-Response Gene, in High-Fat-Diet-Induced Diabetes and Pancreatic {beta}-Cell Dysfunction

E. J Zmuda, L Qi, M. X Zhu, R. G Mirmira, M. R Montminy and T. Hai    

Abstract:

Most people with type 2 diabetes (T2D) have reduced β-cell mass, and apoptosis is a key factor for this reduction. Previously, we showed that ATF3, an adaptive-response gene, is induced by various stress signals relevant to T2D, such as high glucose and high fatty acid. Because ATF3 is proapoptotic in β-cells, we tested the hypothesis that ATF3 plays a detrimental role and contributes to the development of T2D. We compared wild-type (WT) and ATF3 knockout (KO) mice in an animal model for T2D, high-fat diet-induced diabetes. We also used INS-1 β-cells and primary islets to analyze the roles of ATF3 in β-cell function, including insulin gene expression and glucose-induced insulin secretion. Surprisingly, WT mice performed better in glucose tolerance test than KO mice, suggesting a protective, rather than detrimental, role of ATF3. At 12 wk on high-fat diet, no β-cell apoptosis was observed, and the WT and KO mice had comparable β-cell areas. However, ATF3 deficiency significantly reduced serum insulin levels in the KO mice without affecting insulin sensitivity, suggesting reduced β-cell function in the KO mice. Analyses using INS-1 cells and primary islets support the notion that this defect is due, at least partly, to reduced insulin gene transcription in the KO islets without detectable reduction in glucose-induced calcium influx, a critical step for insulin secretion. In conclusion, our results support a model in which, before apoptosis becomes obvious, expression of ATF3 can be beneficial by helping β-cells to cope with higher metabolic demand.

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