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J Biol Chem. 2010 Jun 25;285(26):19910-20. doi: 10.1074/jbc.M110.122374. Epub 2010 Apr 26.

p53 up-regulated modulator of apoptosis (PUMA) activation contributes to pancreatic beta-cell apoptosis induced by proinflammatory cytokines and endoplasmic reticulum stress.

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Laboratory of Experimental Medicine, Université Libre de Bruxelles, Route de Lennik, 808, CP-618, 1070 Brussels, Belgium.


Type 1 diabetes is an autoimmune disorder characterized by chronic inflammation and pancreatic beta-cell loss. Here, we demonstrate that the proinflammatory cytokine interleukin-1beta, combined with interferon-gamma, induces the expression of the Bcl-2 homology 3 (BH3)-only activator PUMA (p53 up-regulated modulator of apoptosis) in beta-cells. Transcriptional activation of PUMA is regulated by nuclear factor-kappaB and endoplasmic reticulum stress but is independent of p53. PUMA activation leads to mitochondrial Bax translocation, cytochrome c release, and caspase-3 cleavage resulting in beta-cell demise. The antiapoptotic Bcl-XL protein is localized mainly at the mitochondria of the beta-cells and antagonizes PUMA action, but Bcl-XL is inactivated by the BH3-only sensitizer DP5/Hrk in cytokine-exposed beta-cells. Moreover, a pharmacological mimic of the BH3-only sensitizer Bad, which inhibits Bcl-XL and Bcl-2, induces PUMA-dependent beta-cell death and potentiates cytokine-induced apoptosis. Our data support a hierarchical activation of BH3-only proteins controlling the intrinsic pathway of beta-cell apoptosis in the context of inflammation and type 1 diabetes.

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