Showing papers by "Allan Z. Zhao published in 2010"

Cellular Production of n-3 PUFAs and Reduction of n-6–to–n-3 Ratios in the Pancreatic β-Cells and Islets Enhance Insulin Secretion and Confer Protection Against Cytokine-Induced Cell Death

Abstract: OBJECTIVE To evaluate the direct impact of n-3 polyunsaturated fatty acids (n-3 PUFAs) on the functions and viability of pancreatic β-cells. RESEARCH DESIGN AND METHODS We developed an mfat-1 transgenic mouse model in which endogenous production of n-3 PUFAs was achieved through overexpressing a C. elegans n-3 fatty acid desaturase gene, mfat -1. The islets and INS-1 cells expressing mfat-1 were analyzed for insulin secretion and viability in response to cytokine treatment. RESULTS The transgenic islets contained much higher levels of n-3 PUFAs and lower levels of n-6 PUFAs than the wild type. Insulin secretion stimulated by glucose, amino acids, and glucagon-like peptide-1 (GLP-1) was significantly elevated in the transgenic islets. When challenged with tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and γ-interferon (IFN-γ), the transgenic islets completely resisted cytokine-induced cell death. Adenoviral transduction of mfat-1 gene in wild-type islets and in INS-1 cells led to acute changes in the cellular levels of n-3- and n-6 PUFAs and recapitulated the results in the transgenic islets. The expression of mfat-1 led to decreased production of prostaglandin E 2 (PGE 2 ), which in turn contributed to the elevation of insulin secretion. We further found that cytokine-induced activation of NF-κB and extracellular signal–related kinase 1/2 (ERK 1/2 ) was significantly attenuated and that the expression of pancreatic duodenal hemeobox-1 (PDX-1), glucokinase, and insulin-1 was increased as a result of n-3 PUFA production. CONCLUSIONS Stable cellular production of n-3 PUFAs via mfat-1 can enhance insulin secretion and confers strong resistance to cytokine-induced β-cell destruction. The utility of mfat-1 gene in deterring type 1 diabetes should be further explored in vivo.