Document Detail

Sustained postexercise increases in AS160 Thr642 and Ser588 phosphorylation in skeletal muscle without sustained increases in kinase phosphorylation.
MedLine Citation:
PMID:  22936728     Owner:  NLM     Status:  MEDLINE    
Prior exercise by rats can induce a sustained increase in muscle Akt substrate of 160 kDa (AS160) phosphorylation on Thr(642) (pAS160(Thr642)). Because phosphorylation of AS160 on both AS160(Thr642) and AS160(Ser588) is important for insulin-stimulated glucose transport (GT), we determined if exercise would also induce a sustained increase in pAS160(Ser588) concomitant with persistently elevated pAS160(Thr642) and GT. Given that the mechanisms for sustained postexercise (PEX) effects on pAS160 were uncertain, we also studied the four kinases known to phosphorylate AS160 (Akt, AMPK, RSK, and SGK1). In addition, because the serine/threonine phosphatase(s) that dephosphorylate muscle AS160 were previously unidentified, we assessed the ability of four serine/threonine phosphatases (PP1, PP2A, PP2B, and PP2C) to dephosphorylate AS160. We also evaluated exercise effects on posttranslational modifications (Tyr(307) and Leu(309)) that regulate PP2A. In isolated epitrochlearis muscles from rats, GT at 3hPEX with insulin significantly (P < 0.05) exceeded SED controls. Muscles from 0hPEX vs. 0hSED and 3hPEX vs. 3hSED rats had greater pAS160(Thr642) and pAS160(Ser588). AMPK was the only kinase with greater phosphorylation at 0hPEX vs. 0hSED, and none had greater phosphorylation at 3hPEX vs. 3hSED. Each phosphatase was able to dephosphorylate pAS160(Thr642) and pAS160(Ser588) in cell-free assays. Exercise did not alter posttranslational modifications of PP2A. Our results revealed: 1) pAMPK as a potential trigger for increased pAS160(Thr642) and pAS160(Ser588) at 0hPEX; 2) PP1, PP2A, PP2B, and PP2C were each able to dephosphorylate AS160; and 3) sustained PEX-induced elevations of pAS160(Thr642) and pAS160(Ser588) were attributable to mechanisms other than persistent phosphorylation of known AS160 kinases or altered posttranslational modifications of PP2A.
George G Schweitzer; Edward B Arias; Gregory D Cartee
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-08-30
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-17     Completed Date:  2013-06-14     Revised Date:  2014-08-29    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1852-61     Citation Subset:  IM    
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MeSH Terms
Binding Sites
GTPase-Activating Proteins / metabolism*
Muscle Contraction / physiology*
Phosphotransferases / metabolism*
Physical Endurance / physiology*
Physical Exertion / physiology*
Protein Binding
Rats, Wistar
Serine / metabolism*
Threonine / metabolism*
Grant Support
Reg. No./Substance:
0/GTPase-Activating Proteins; 0/LOC686547 protein, rat; 2ZD004190S/Threonine; 452VLY9402/Serine; EC 2.7.-/Phosphotransferases

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