| First Author | Koyanagi M | Year | 2011 |
| Journal | PLoS One | Volume | 6 |
| Issue | 8 | Pages | e23238 |
| PubMed ID | 21886784 | Mgi Jnum | J:176342 |
| Mgi Id | MGI:5291519 | Doi | 10.1371/journal.pone.0023238 |
| Citation | Koyanagi M, et al. (2011) Ablation of TSC2 Enhances Insulin Secretion by Increasing the Number of Mitochondria through Activation of mTORC1. PLoS One 6(8):e23238 |
| abstractText | AIM: We previously found that chronic tuberous sclerosis protein 2 (TSC2) deletion induces activation of mammalian target of rapamycin Complex 1 (mTORC1) and leads to hypertrophy of pancreatic beta cells from pancreatic beta cell-specific TSC2 knockout (betaTSC2(-/-)) mice. The present study examines the effects of TSC2 ablation on insulin secretion from pancreatic beta cells. METHODS: Isolated islets from betaTSC2(-/-) mice and TSC2 knockdown insulin 1 (INS-1) insulinoma cells treated with small interfering ribonucleic acid were used to investigate insulin secretion, ATP content and the expression of mitochondrial genes. RESULTS: Activation of mTORC1 increased mitochondrial DNA expression, mitochondrial density and ATP production in pancreatic beta cells of betaTSC2(-/-) mice. In TSC2 knockdown INS-1 cells, mitochondrial DNA expression, mitochondrial density and ATP production were increased compared with those in control INS-1 cells, consistent with the phenotype of betaTSC2(-/-) mice. TSC2 knockdown INS-1 cells also exhibited augmented insulin secretory response to glucose. Rapamycin inhibited mitochondrial DNA expression and ATP production as well as insulin secretion in response to glucose. Thus, betaTSC2(-/-) mice exhibit hyperinsulinemia due to an increase in the number of mitochondria as well as enlargement of individual beta cells via activation of mTORC1. CONCLUSION: Activation of mTORC1 by TSC2 ablation increases mitochondrial biogenesis and enhances insulin secretion from pancreatic beta cells. |
