Leucine Culture Reveals That ATP Synthase Functions as a Fuel Sensor in Pancreatic β-Cells

• Published in: The Journal of biological chemistry 2004-12, Vol.279 (52), p.53915
• Main Authors: Jichun Yang, Ryan K. Wong, Xujing Wang, Jacob Moibi, Martin J. Hessner, Scott Greene, Jianmei Wu, Siam Sukumvanich, Bryan A. Wolf, Zhiyong Gao
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M405309200

Our goal was to investigate whether leucine culture affects β-cell glucose sensing. One-day culture of rat islets with 10 m m leucine had no effect on glucose-induced insulin secretion. One-week leucine culture decreased the threshold for glucose-induced insulin secretion and increased maximal insulin secretion at 30 m m glucose. Glucose-induced cytosolic free Ca 2+ was increased at 1 week but not at 1 day of leucine culture. Without glucose, ATP content was not different with or without leucine culture for 1 week. With 20 m m glucose, ATP content was higher by 1.5-fold in islets cultured for 1 week with leucine than those without leucine. Microarray experiments indicated that culture of RINm5F cells with leucine increased expression of ATP synthase β subunit 3.2-fold, which was confirmed by real time reverse transcription-PCR analysis (3.0- ± 0.4-fold) in rat islets at 1 week but not after 1 day with leucine culture. Down-regulation of ATP synthase β subunit by siRNA decreased INS1 cell ATP content and insulin secretion with 20 m m glucose. Overexpression of ATP synthase β subunit in INS1 cell increased insulin secretion in the presence of 5 and 20 m m glucose. In conclusion, one-week leucine culture of rat islets up-regulated ATP synthase and increased ATP content, which resulted in elevated [Ca 2+ ] levels and more insulin exocytosis by glucose. Depletion of ATP synthase β subunit with siRNA produced opposite effects. These data reveal the fuel-sensing role of mitochondrial ATP synthase in the control of ATP production from glucose and the control of glucose-induced insulin secretion.