Adrenaline potentiates insulin-stimulated PKB activation in the rat fast-twitch epitrochlearis muscle without affecting IRS-1-associated PI 3-kinase activity

Jensen, Jørgen, Gronning-Wang, Line M., Jebens, Einar, Whitehead, Jonathan P., Zorec, Robert and Shepherd, Peter R. (2008) Adrenaline potentiates insulin-stimulated PKB activation in the rat fast-twitch epitrochlearis muscle without affecting IRS-1-associated PI 3-kinase activity. Pflügers Archiv European Journal of Physiology, 456 5: 969-978. doi:10.1007/s00424-008-0471-z


Author Jensen, Jørgen
Gronning-Wang, Line M.
Jebens, Einar
Whitehead, Jonathan P.
Zorec, Robert
Shepherd, Peter R.
Title Adrenaline potentiates insulin-stimulated PKB activation in the rat fast-twitch epitrochlearis muscle without affecting IRS-1-associated PI 3-kinase activity
Journal name Pflügers Archiv European Journal of Physiology   Check publisher's open access policy
ISSN 0031-6768
1432-2013
Publication date 2008-08-01
Year available 2008
Sub-type Article (original research)
DOI 10.1007/s00424-008-0471-z
Open Access Status Not yet assessed
Volume 456
Issue 5
Start page 969
End page 978
Total pages 10
Place of publication The United States of America
Publisher Springer
Language eng
Subject C1
110306 Endocrinology
970111 Expanding Knowledge in the Medical and Health Sciences
Abstract We have previously shown in the rat slow-twitch soleus muscle that adrenaline greatly potentiates insulin-stimulated protein kinase B (PKB) phosphorylation without having an effect alone. However, insulin signalling capacity through the PKB pathway is higher in soleus than in fast-twitch muscles, whereas adrenaline activates phosphorylase more strongly in epitrochlearis. Therefore, the aim of the present study was to investigate the interaction between adrenaline and insulin signalling in the fast-twitch epitrochlearis muscle. Insulin increased insulin receptor substrate-1 (IRS-1)-associated phosphoinositide (PI) 3-kinase activity threefold, and adrenaline did not influence basal or insulin-stimulated PI 3-kinase activity. Insulin but not adrenaline increased PKB activity and phosphorylation of Ser473 and Thr308. It is interesting to note that adrenaline potentiated insulin-stimulated PKB activity and PKB Ser473 and Thr308 phosphorylation. These effects were mimicked by dibutyryl-cyclic adenosine monophosphate (db-cAMP). Adrenaline and db-cAMP increased glycogen synthase kinase (GSK)-3β Ser9 phosphorylation independently of PKB activation and enhanced insulin-stimulated GSK-3β Ser9 phosphorylation. Although adrenaline increased GSK-3 phosphorylation (inhibiting activity), phosphorylation of its target sites on glycogen synthase was increased, and adrenaline blocked insulin-stimulated glycogen synthase dephosphorylation of Ser641 and Ser645,649,653,657, glycogen synthase activation and glycogen synthesis. Insulin-stimulated glucose transport was not influenced by adrenaline despite the increased PKB activation. In conclusion, as in the slow-twitch soleus muscle, adrenaline potentiates insulin-stimulated PKB activation in the fast-twitch glycolytic epitrochlearis muscle without increasing IRS-1-associated PI 3-kinase activity. Furthermore, adrenaline induces phosphorylation of a pool of GSK-3 that is not involved in the regulation of glycogen metabolism. These results indicate that the combination of adrenaline and insulin may activate novel signalling molecules rather than just summing up their effects on linear pathways.
Keyword Glycogen synthase
Glucose transport
cAMP
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
UQ Diamantina Institute Publications
 
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Created: Thu, 26 Mar 2009, 22:57:52 EST by Kylie Hengst on behalf of UQ Diamantina Institute