Nutrient Sensor mTORC1 Regulates Insulin Secretion by Modulating β-Cell Autophagy

Tal Israeli, Yael Riahi, Perla Garzon, Ruy Andrade Louzada, Joao Pedro Werneck-De-castro, Manuel Blandino-Rosano, Roni Yeroslaviz-Stolper, Liat Kadosh, Sharona Tornovsky-Babeay, Gilad Hacker, Nitzan Israeli, Orly Agmon, Boaz Tirosh, Erol Cerasi, Ernesto Bernal-Mizrachi, Gil Leibowitz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The dynamic regulation of autophagy in β-cells by cycles of fasting-feeding and its effects on insulin secretion are unknown. In β-cells, mechanistic target of rapamycin complex 1 (mTORC1) is inhibited while fasting and is rapidly stimulated during refeeding by a single amino acid, leucine, and glucose. Stimulation of mTORC1 by nutrients inhibited the autophagy initiator ULK1 and the transcription factor TFEB, thereby preventing autophagy when β-cells were continuously exposed to nutrients. Inhibition of mTORC1 by Raptor knockout mimicked the effects of fasting and stimulated autophagy while inhibiting insulin secretion, whereas moderate inhibition of autophagy under these conditions rescued insulin secretion. These results show that mTORC1 regulates insulin secretion through modulation of autophagy under different nutritional situations. In the fasting state, autophagy is regulated in an mTORC1-dependent manner, and its stimulation is required to keep insulin levels low, thereby preventing hypoglycemia. Recip-rocally, stimulation of mTORC1 by elevated leucine and glucose, which is common in obesity, may promote hyper-insulinemia by inhibiting autophagy.

Original languageAmerican English
Pages (from-to)453-469
Number of pages17
JournalDiabetes
Volume71
Issue number3
DOIs
StatePublished - 1 Mar 2022

Bibliographical note

Publisher Copyright:
© 2022 by the American Diabetes Association.

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