Eukaryotic Initiation Factor 4E (eIF4E) sequestration mediates 4E-BP1 response to rapamycin.
Int J Biol Macromol
; 125: 651-659, 2019 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-30552925
ABSTRACT
The cap dependent translation initiation is a tightly controlled process of cooperative ternary complex formation by 4E-BP1, eIF4E and the 5' cap of eukaryotic mRNA in response to environmental cues like glucose, nutrients and growth factor levels. Based on the well-described effects of mTORC1/rapamycin complex on 4E-BP1 phosphorylation/s, it is generally accepted that rapamycin is a global inhibitor of cap-dependent translation. We have previously shown that 4E-BP1 resistance to rapamycin was overcome by the stoichiometric abundance of S6K1. Now we present evidence that the TOS-bearing amino terminal domain of S6K1 is sufficient to relieve the rapamycin resistance of 4E-BP1 as TOS deleted variants of S6K1, active or inactive with regard to S6K1 activity failed to bring about relief of 4E-BP1 resistance to rapamycin. We also show that the reciprocal inactivation of S6K1 by abundance of 4E-BP1 gets accomplished only with intact TOS motif in the protein. The data presented in this study identifies eIF4E and not Raptor as a cellular factor responsible to regulate rapamycin sensitivity of 4E-BP1 suggesting that the phosphorylation dynamics and rapamycin sensitivity of 4E-BP1 and S6K1 are regulated independently.
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MEDLINE
Assunto principal:
Fosfoproteínas
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Sirolimo
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Fator de Iniciação 4E em Eucariotos
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Proteínas Adaptadoras de Transdução de Sinal
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article