Wang, X.M. and Flynn, A. and Waskiewicz, A.J. and Webb, B.L.J. and Vries, R.G. and Baines, I.A. and Cooper, J.A. and Proud, C.G. (1998) The phosphorylation of eukaryotic initiation factor eIF4E in response to phorbol esters, cell stresses, and cytokines is mediated by distinct MAP kinase pathways. Journal of Biological Chemistry, 273 (16). pp. 9373-9377. ISSN 0021-9258.
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Initiation factor eIF4E binds to the 5'-cap of eukaryotic mRNAs and plays a key role in the mechanism and regulation of translation. It may be regulated through its own phosphorylation and through inhibitory binding proteins (4E-BPs), which modulate its availability for initiation complex assembly. eIF4E phosphorylation is enhanced by phorbol esters. We show, using specific inhibitors, that this involves both the p38 mitogen-activated protein (MAP) kinase and Erk signaling pathways. Cell stresses such as arsenite and anisomycin and the cytokines tumor necrosis factor-alpha and interleukin-1 beta also cause increased phosphorylation of eIF4E, which is abolished by the specific p38 MAP kinase inhibitor, SB203580. These changes in eIF4E phosphorylation parallel the activity of the eIF4E kinase, Mnk1. However other stresses such as heat shock, sorbitol, and H2O2, which also stimulate p38 MAP kinase and increase Mnk1 activity, do not increase phosphorylation of eIF4E. The latter stresses increase the binding of eIF4E to 4E-BP1, and me show that this blocks the phosphorylation of eIF4E by Mnk1 in vitro, which may explain the absence of an increase in eIF4E phosphorylation under these conditions.
Q Science > QP Physiology (Living systems) > QP517 Biochemistry
Q Science > QP Physiology (Living systems) > QP506 Molecular biology
|Divisions:||Faculties > Science Technology and Medical Studies > School of Biosciences|
|Depositing User:||Tara Puri|
|Date Deposited:||27 May 2009 10:33|
|Last Modified:||27 May 2009 10:33|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/17252 (The current URI for this page, for reference purposes)|
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