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J Biol Chem. 2019 Aug 9;294(32):12250-12260. doi: 10.1074/jbc.RA119.008488. Epub 2019 Jun 26.

Inhibition of mitochondrial complex 1 by the S6K1 inhibitor PF-4708671 partly contributes to its glucose metabolic effects in muscle and liver cells.

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Department of Medicine, Quebec Heart and Lung Institute, Université Laval, Québec G1V 4G5, Canada.
INSERM, U1016, Institut Cochin, 75014 Paris, France.
CNRS, UMR8104, 75014 Paris, France.
Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France.
Department of Medicine, Quebec Heart and Lung Institute, Université Laval, Québec G1V 4G5, Canada


mTOR complex 1 (mTORC1) and p70 S6 kinase (S6K1) are both involved in the development of obesity-linked insulin resistance. Recently, we showed that the S6K1 inhibitor PF-4708671 (PF) increases insulin sensitivity. However, we also reported that PF can increase glucose metabolism even in the absence of insulin in muscle and hepatic cells. Here we further explored the potential mechanisms by which PF increases glucose metabolism in muscle and liver cells independent of insulin. Time course experiments revealed that PF induces AMP-activated protein kinase (AMPK) activation before inhibiting S6K1. However, PF-induced glucose uptake was not prevented in primary muscle cells from AMPK α1/2 double KO (dKO) mice. Moreover, PF-mediated suppression of hepatic glucose production was maintained in hepatocytes derived from AMPK α1/2-dKO mice. Remarkably, PF could still reduce glucose production and activate AMPK in hepatocytes from S6K1/2 dKO mice. Mechanistically, bioenergetics experiments revealed that PF reduces mitochondrial complex I activity in both muscle and hepatic cells. The stimulatory effect of PF on glucose uptake was partially reduced by expression of the Saccharomyces cerevisiae NADH:ubiquinone oxidoreductase in L6 cells. These results indicate that PF-mediated S6K1 inhibition is not required for its effect on insulin-independent glucose metabolism and AMPK activation. We conclude that, although PF rapidly activates AMPK, its ability to acutely increase glucose uptake and suppress glucose production does not require AMPK activation. Unexpectedly, PF rapidly inhibits mitochondrial complex I activity, a mechanism that partially underlies PF's effect on glucose metabolism.


AMPK-activated protein kinase (AMPK); PF-4708671; diabetes; gluconeogenesis; glucose homeostasis; glucose metabolism; mechanistic target of rapamycin (mTOR); mitochondrial complex I; obesity; p70 S6 kinase (S6K1)

[Available on 2020-08-09]

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