Pyruvate Kinase Controls Signal Strength in the Insulin Secretory Pathway

Abstract

Pancreatic β-cells couple nutrient metabolism with appropriate insulin secretion. Here, we show that pyruvate kinase (PK), which converts ADP and phosphoenolpyruvate (PEP) into ATP and pyruvate, underlies β-cell sensing of both glycolytic and mitochondrial fuels. PK present at the plasma membrane is sufficient to close KATP channels and initiate calcium influx. Small-molecule PK activators increase β-cell oscillation frequency and potently amplify insulin secretion. By cyclically depriving mitochondria of ADP, PK restricts oxidative phosphorylation in favor of the mitochondrial PEP cycle with no net impact on glucose oxidation. Our findings support a compartmentalized model of β-cell metabolism in which PK locally generates the ATP/ADP threshold required for insulin secretion, and identify a potential therapeutic route for diabetes based on PK activation that would not be predicted by the β-cell consensus model.