Report

Requirement of Inositol Pyrophosphates for Full Exocytotic Capacity in Pancreatic β Cells

Science  23 Nov 2007:
Vol. 318, Issue 5854, pp. 1299-1302
DOI: 10.1126/science.1146824

You are currently viewing the abstract.

View Full Text

Via your Institution

Log in through your institution

Log in through your institution


Abstract

Inositol pyrophosphates are recognized components of cellular processes that regulate vesicle trafficking, telomere length, and apoptosis. We observed that pancreatic β cells maintain high basal concentrations of the pyrophosphate diphosphoinositol pentakisphosphate (InsP7 or IP7). Inositol hexakisphosphate kinases (IP6Ks) that can generate IP7 were overexpressed. This overexpression stimulated exocytosis of insulin-containing granules from the readily releasable pool. Exogenously applied IP7 dose-dependently enhanced exocytosis at physiological concentrations. We determined that IP6K1 and IP6K2 were present in β cells. RNA silencing of IP6K1, but not IP6K2, inhibited exocytosis, which suggests that IP6K1 is the critical endogenous kinase. Maintenance of high concentrations of IP7 in the pancreatic β cell may enhance the immediate exocytotic capacity and consequently allow rapid adjustment of insulin secretion in response to increased demand.

View Full Text

Cited By...