PHLPP1 deletion restores pancreatic β-cell survival and normoglycemia in the db/db mouse model of obesity-associated diabetes.

The Pleckstrin homology domain leucine-rich repeat protein phosphatases (PHLPPs) are novel therapeutic targets for the restoration of β-cell survival and function in diabetes. Their upregulation and activation in β-cells under conditions of both type 1 and type 2 diabetes directly correlates with β-cell failure; β-cell death and loss of insulin secretory function through disturbance of cell survival control mechanisms. PHLPPs directly dephosphorylate and regulate activities of β-cell survival-dependent kinases AKT and MST1 constituting a regulatory triangle loop to control β-cell apoptosis. PHLPP1 deletion in severely diabetic leptin receptor-deficient db/db mice restored normoglycemia and β-cell area through increased β-cell proliferation and reduced β-cell apoptosis. The beneficial effects of PHLPP1 deficiency in a severe mouse model of obesity and diabetes make PHLPP a new target for β-cell-directed diabetes therapy.