The effects of mTOR-Akt interactions on anti-apoptotic signaling in vascular endothelial cells.

Details

Serval ID
serval:BIB_1F80BEF7C77D
Type
Article: article from journal or magazin.
Collection
Publications
Title
The effects of mTOR-Akt interactions on anti-apoptotic signaling in vascular endothelial cells.
Journal
Journal of Biological Chemistry
Author(s)
Dormond O., Madsen J.C., Briscoe D.M.
ISSN
0021-9258[print], 0021-9258[linking]
Publication state
Published
Issued date
2007
Volume
282
Number
32
Pages
23679-23686
Language
english
Notes
Publication types: Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
Abstract
Recent studies have determined that mTOR mediates the activation of the protein kinase Akt in several cell types, but little is known about the association between mTOR and Akt in vascular endothelial cells. Furthermore, the functional significance of mTOR/Akt signaling has not been characterized in the endothelium. In these studies we treated endothelial cells with the mTOR inhibitor rapamycin, and we found that it decreases Akt phosphorylation and activity, as determined by phosphorylation of its substrate glycogen synthase kinase-3. This effect of rapamycin on Akt phosphorylation could not be demonstrated in endothelial cells transfected with a rapamycin-resistant mTOR construct. Also, in the presence of rapamycin, vascular endothelial growth factor, tumor necrosis factor, and insulin failed to phosphorylate Akt, further indicating that mTOR regulates Akt activation in endothelial cells. The activation of Akt is well established to mediate pro-survival signals. In part this is mediated via the phosphorylation and inactivation of the pro-apoptotic Akt substrates Foxo1 and Foxo3a. We find that rapamycin totally blocks vascular endothelial growth factor and Akt-inducible phosophorylation of these transcription factors in endothelial cells. Furthermore, inhibition of Akt activity by rapamycin increased the number of endothelial cells undergoing apoptosis after serum withdrawal as well as after stimulation by vascular endothelial growth factor or tumor necrosis factor. Taken together these observations demonstrate first, that mTOR regulates the phosphorylation and activation of Akt in endothelial cells and, second, that a major effect of mTOR inhibition in endothelial cells is to suppress Akt-inducible pro-survival signals.
Keywords
Apoptosis, Endothelial Cells/cytology, Endothelium, Vascular/cytology, Forkhead Transcription Factors/metabolism, Gene Expression Regulation, Humans, Models, Biological, Phosphorylation, Protein Binding, Protein Kinases/metabolism, Proto-Oncogene Proteins c-akt/metabolism, Signal Transduction, Sirolimus/pharmacology, TOR Serine-Threonine Kinases, Vascular Endothelial Growth Factor A/metabolism
Pubmed
Web of science
Open Access
Yes
Create date
07/03/2011 10:26
Last modification date
20/08/2019 13:55
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