Heat shock increases the association of binding protein-1 with initiation factor 4E.
The effects of heat shock on the regulation of the cap-binding initiation factor 4E (eIF4E) and its inhibitory binding protein, 4E-BP1, have been examined in Chinese hamster ovary cells and in cardiac myocytes. Heat shock increased the association between eIF4E and 4E-BP1, and this was associated with a dephosphorylation of 4E-BP1. These effects did not appear to be due wholly to decreased activity of the p70 S6 kinase pathway, which is implicated in the control of 4E-BP1, and they were not mediated by the stress-activated p38 microtubule-associated protein kinase pathway. Increased binding of 4E-BP1 to eIF4E correlated with a decrease in the amount of eIF4G which co-purified with the latter. This could account for the previously observed impairment of eIF4F function during heat shock, and, since heat shock protein mRNAs are believed to be relatively cap-independent, could provide a mechanism for the selective up-regulation of the synthesis of heat shock proteins and other stress proteins during heat shock.
Vries
R G
RG
Department of Biosciences, University of Kent at Canterbury, Canterbury, CT2 7NJ, United Kingdom.
Flynn
A
A
Patel
J C
JC
Wang
X
X
Denton
R M
RM
Proud
C G
CG
D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins; D006224:Cricetinae; D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D006358:Hot Temperature; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D012097:Repressor Proteins / Q000378:metabolism*
D002352:Carrier Proteins; C499526:Eif4ebp1 protein, rat; D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D047908:Intracellular Signaling Peptides and Proteins; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D012097:Repressor Proteins