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Journal of molecular signaling 2010, PMID: 20167101

AMPK exerts dual regulatory effects on the PI3K pathway.

Tao, Rong; Gong, Jun; Luo, Xixi; Zang, Mengwei; Guo, Wen; Wen, Rong; Luo, Zhijun

BACKGROUND

AMP-activated protein kinase (AMPK) is a fuel-sensing enzyme that is activated when cells experience energy deficiency and conversely suppressed in surfeit of energy supply. AMPK activation improves insulin sensitivity via multiple mechanisms, among which AMPK suppresses mTOR/S6K-mediated negative feedback regulation of insulin signaling.

RESULTS

In the present study we further investigated the mechanism of AMPK-regulated insulin signaling. Our results showed that 5-aminoimidazole-4-carboxamide-1 ribonucleoside (AICAR) greatly enhanced the ability of insulin to stimulate the insulin receptor substrate-1 (IRS1)-associated PI3K activity in differentiated 3T3-F442a adipocytes, leading to increased Akt phosphorylation at S473, whereas insulin-stimulated activation of mTOR was diminished. In 3T3-F442a preadipocytes, these effects were attenuated by expression of a dominant negative mutant of AMPK alpha1 subunit. The enhancing effect of ACIAR on Akt phosphorylation was also observed when the cells were treated with EGF, suggesting that it is regulated at a step beyond IR/IRS1. Indeed, when the cells were chronically treated with AICAR in the absence of insulin, Akt phosphorylation was progressively increased. This event was associated with an increase in levels of phosphatidylinositol -3,4,5-trisphosphate (PIP3) and blocked by Wortmannin. We then expressed the dominant negative mutant of PTEN (C124S) and found that the inhibition of endogenous PTEN per se did not affect phosphorylation of Akt at basal levels or upon treatment with AICAR or insulin. Thus, this result suggests that AMPK activation of Akt is not mediated by regulating phosphatase and tensin homologue (PTEN).

CONCLUSIONS

Our present study demonstrates that AMPK exerts dual effects on the PI3K pathway, stimulating PI3K/Akt and inhibiting mTOR/S6K.

Document information provided by NCBI PubMed

Text Mining Data

insulin ⊣ mTOR/S6K: " AMPK activation improves insulin sensitivity via multiple mechanisms, among which AMPK suppresses mTOR/S6K mediated negative feedback regulation of insulin signaling "

insulin → AMPK: " AMPK activation improves insulin sensitivity via multiple mechanisms, among which AMPK suppresses mTOR/S6K mediated negative feedback regulation of insulin signaling "

insulin — AMPK: " In the present study we further investigated the mechanism of AMPK regulated insulin signaling "

mTOR → insulin: " Our results showed that 5-aminoimidazole-4-carboxamide-1 ribonucleoside ( AICAR ) greatly enhanced the ability of insulin to stimulate the insulin receptor substrate-1 (IRS1) associated PI3K activity in differentiated 3T3-F442a adipocytes, leading to increased Akt phosphorylation at S473, whereas insulin stimulated activation of mTOR was diminished "

PI3K → mTOR: " Our results showed that 5-aminoimidazole-4-carboxamide-1 ribonucleoside ( AICAR ) greatly enhanced the ability of insulin to stimulate the insulin receptor substrate-1 (IRS1) associated PI3K activity in differentiated 3T3-F442a adipocytes, leading to increased Akt phosphorylation at S473, whereas insulin stimulated activation of mTOR was diminished "

PI3K → insulin: " Our results showed that 5-aminoimidazole-4-carboxamide-1 ribonucleoside ( AICAR ) greatly enhanced the ability of insulin to stimulate the insulin receptor substrate-1 (IRS1) associated PI3K activity in differentiated 3T3-F442a adipocytes, leading to increased Akt phosphorylation at S473, whereas insulin stimulated activation of mTOR was diminished "

Akt — PTEN: " We then expressed the dominant negative mutant of PTEN ( C124S ) and found that the inhibition of endogenous PTEN per se did not affect phosphorylation of Akt at basal levels or upon treatment with AICAR or insulin "

Akt → phosphatase and tensin homologue (PTEN): " Thus, this result suggests that AMPK activation of Akt is not mediated by regulating phosphatase and tensin homologue (PTEN) "

AMPK → Akt: " Thus, this result suggests that AMPK activation of Akt is not mediated by regulating phosphatase and tensin homologue (PTEN) "

AMPK → phosphatase and tensin homologue (PTEN): " Thus, this result suggests that AMPK activation of Akt is not mediated by regulating phosphatase and tensin homologue (PTEN) "

PI3K/Akt ⊣ mTOR/S6K: " Our present study demonstrates that AMPK exerts dual effects on the PI3K pathway, stimulating PI3K/Akt and inhibiting mTOR/S6K "

mTOR/S6K ⊣ PI3K/Akt: " Our present study demonstrates that AMPK exerts dual effects on the PI3K pathway, stimulating PI3K/Akt and inhibiting mTOR/S6K "

Manually curated Databases

No curated data.