Adiponectin sensitizes insulin signaling by reducing p70 S6 kinase-mediated serine phosphorylation of IRS-1

Changhua Wang, Xuming Mao, Lixin Wang, Meilian Liu, Michael D. Wetzel, Kun Liang Guan, Lily Q. Dong, Feng Liu

Research output: Contribution to journalArticlepeer-review

144 Scopus citations

Abstract

Adiponectin functions as an insulin sensitizer, and yet the underlying molecular mechanism(s) remains largely unknown. We found that treating C2C12 myotubes with adiponectin or rapamycin enhanced the ability of insulin to stimulate IRS-1 tyrosine phosphorylation and Akt phosphorylation, concurrently with reduced p70 S6 kinase phosphorylation at Thr389 as well as IRS-1 phosphorylation at Ser302 and Ser636/639. Overexpression of dominant-negative AMP kinase (AMPK), but not dominant-negative p38 MAPK, reduced the insulin-sensitizing effect of adiponectin. Rapamycin, but not adiponectin, enhanced insulin-stimulated Akt phosphorylation in HeLa cells, which lack LKB1,and exogenous expression of LKB1 in HeLa cells rescued the insulin-sensitizing effect of adiponectin. Finally, overexpression of wild-type Rheb (Ras homology-enriched in brain) or the TSC2 mutant lacking the AMPK phosphorylation site (TSC2S1345A) inhibited the insulin-sensitizing effect of adiponectin in C2C12 cells. These results indicate that activation of the LKB1/AMPK/TSC1/2 pathway alleviates the p70 S6 kinase-mediated negative regulation of insulin signaling, providing a mechanism by which adiponectin increases insulin sensitivity in cells.

Original languageEnglish (US)
Pages (from-to)7991-7996
Number of pages6
JournalJournal of Biological Chemistry
Volume282
Issue number11
DOIs
StatePublished - Mar 16 2007

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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