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The T-cell receptor regulates Akt (protein kinase B) via a pathway involving Rac1 and phosphatidylinositide 3-kinase

Genot, E. M. and Arrieumerlou, C. and Ku, G. and Burgering, B. M. and Weiss, A. and Kramer, I. M.. (2000) The T-cell receptor regulates Akt (protein kinase B) via a pathway involving Rac1 and phosphatidylinositide 3-kinase. Molecular and cellular biology, Vol. 20, H. 15. pp. 5469-5478.

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Official URL: http://edoc.unibas.ch/dok/A5259792

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Abstract

The serine/threonine kinase Akt (also known as protein kinase B) (Akt/PKB) is activated upon T-cell antigen receptor (TCR) engagement or upon expression of an active form of phosphatidylinositide (PI) 3-kinase in T lymphocytes. Here we report that the small GTPase Rac1 is implicated in this pathway, connecting the receptor with the lipid kinase. We show that in Jurkat cells, activated forms of Rac1 or Cdc42, but not Rho, stimulate an increase in Akt/PKB activity. TCR-induced Akt/PKB activation is inhibited either by PI 3-kinase inhibitors (LY294002 and wortmannin) or by overexpression of a dominant negative mutant of Rac1 but not Cdc42. Accordingly, triggering of the TCR rapidly stimulates a transient increase in GTP-Rac content in these cells. Similar to TCR stimulation, L61Rac-induced Akt/PKB kinase activity is also LY294002 and wortmannin sensitive. However, induction of Akt/PKB activity by constitutive active PI 3-kinase is unaffected when dominant negative Rac1 is coexpressed, placing Rac1 upstream of PI 3-kinase in the signaling pathway. When analyzing the signaling hierarchy in the pathway leading to cytoskeleton rearrangements, we found that Rac1 acts downstream of PI 3-kinase, a finding that is in accordance with numerous studies in fibroblasts. Our results reveal a previously unrecognized role of the GTPase Rac1, acting upstream of PI 3-kinase in linking the TCR to Akt/PKB. This is the first report of a membrane receptor employing Rac1 as a downstream transducer for Akt/PKB activation.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Molecular Microbiology (Arrieumerlou)
UniBasel Contributors:Arrieumerlou, C├ęcile
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Society for Microbiology
ISSN:1098-5549
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:21
Deposited On:22 Mar 2012 13:23

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