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Poly(ADP-ribose) polymerase-deficient mice are protected from streptozotocin-induced diabetes
A A Pieper1, D J Brat, D K Krug
1Departments of Neuroscience, Pharmacology and Molecular Sciences, and Psychiatry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
Abstract:
Streptozotocin (STZ) selectively destroys insulin-producing beta islet cells of the pancreas providing a model of type I diabetes. Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme whose overactivation by DNA strand breaks depletes its substrate NAD+ and then ATP, leading to cellular death from energy depletion. We demonstrate DNA damage and a major activation of PARP in pancreatic islets of STZ-treated mice. These mice display a 500% increase in blood glucose and major pancreatic islet damage. In mice with homozygous targeted deletion of PARP (PARP -/-), blood glucose and pancreatic islet structure are normal, indicating virtually total protection from STZ diabetes. Partial protection occurs in PARP +/- animals. Thus, PARP activation may participate in the pathophysiology of type I diabetes, for which PARP inhibitors might afford therapeutic benefit.