Uncoupling Protein 2 and Islet Function

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Abstract
Stressors such as chronic hyperglycemia or hyperlipidemia may lead to insufficient insulin secretion in susceptible individuals, contributing to type 2 diabetes. The molecules mediating this effect are just beginning to be identified. Uncoupling protein (UCP)-2 may be one such negative modulator of insulin secretion. Accumulating evidence shows that β-cell UCP2 expression is upregulated by glucolipotoxic conditions and that increased activity of UCP2 decreases insulin secretion. Mitochondrial superoxide has been identified as a posttranslational regulator of UCP2 activity in islets; thus, UCP2 may provide protection to β-cells at one level while simultaneously having detrimental effects on insulin secretion. Interestingly, the latter appears to be the dominant outcome, because UCP2 knockout mice display an increased β-cell mass and retained insulin secretion capacity in the face of glucolipotoxicity.