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Crosstalk between the AMP-activated kinase and insulin signaling pathways rescues murine blastocyst cells from insulin resistance

E Louden, Obstetrics and Gynecology, Washington University, St. Louis, United States
M Chi, Obstetrics and Gynecology, Washington University, St. Louis, United States
K Moley, Obstetrics and Gynecology, Washington University, St.Louis, United States

Correspondence: Kelle Moley, Email: moleyk{at}wustl.edu

Abstract

Maternal insulin resistance results in poor pregnancy outcomes. In vivo and in vitro exposure of the murine blastocyst to high insulin or IGF-1 results in the down-regulation of the IGF-1 receptor (IGF-1R). This in turn leads to decreased glucose uptake, increased apoptosis as well as pregnancy resorptions and growth restriction. Recent studies have shown that blastocyst activation of AMP-activated protein kinase (AMPK) reverses these detrimental effects however the mechanism was not clear. The objective of this study was to determine how AMPK activation rescues the insulin-resistant blastocyst. Using trophoblast stem (TS) cells derived from the blastocyst, insulin resistance was recreated by transfecting with siRNA to IGF-1R and down-regulating expression of the protein. These cells were then exposed to AMPK activators AICAR and Phenformin and evaluated for apoptosis, insulin-stimulated 2-deoxyglucose uptake, PI3Kinase activity and levels of Phospho-Akt, -mTor and -70S6K. Surprisingly, disrupted insulin signaling led to decreased AMPK activity in TS cells. Activators reversed these effects by increasing the AMP/ATP ratio. Moreover this treatment increased insulin-stimulated 2-deoxyglucose transport and cell survival and led to an increase in PI3Kinase activity as well as increased P-mTOR and P-70S6K levels. This study is the first to demonstrate significant crosstalk between the AMPK and insulin-signaling pathway in embryonic cells, specifically the enhanced response of PI3K/Akt/mTOR to AMPK activation. Decreased insulin signaling also resulted in decreased AMPK activation. These findings provide mechanistic targets in the AMPK signaling pathway that may be essential for improved pregnancy success in insulin-resistant states.