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Title: Mitotic protein kinase CDK1 phosphorylation of mRNA translation regulator 4E-BP1 Ser83 may contribute to cell transformation

mTOR-directed 4E-BP1 phosphorylation promotes cap-dependent translation and tumorigen-esis. During mitosis, CDK1 substitutes for mTOR and fully phosphorylates 4E-BP1 at canoni-cal as well a non-canonical S83 site resulting in a mitosis-specific hyperphosphorylated δ isoform. Colocalization studies with a phospho-S83 specific antibody indicate that 4E-BP1 S83 phosphorylation accumulates at centrosomes during prophase, peaks at metaphase, and decreases through telophase. While S83 phosphorylation of 4E-BP1 does not affect in vitro cap-dependent translation, nor eIF4G/4E-BP1 cap-binding, expression of an alanine substitution mutant 4E-BP1.S83A partially reverses rodent cell transformation induced by Merkel cell polyomavirus (MCV) small T (sT) antigen viral oncoprotein. In contrast to inhibitory mTOR 4E-BP1 phosphorylation, these findings suggest that mitotic CDK1-directed phosphorylation of δ-4E-BP1 may yield a gain-of-function, distinct from translation regulation, that may be important in tumorigenesis and mitotic centrosome function.
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Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America, vol. 113(30):8466-8471
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
Country of Publication:
United States
4E-BP1; cyclin-dependent kinase 1; centrosome; mitosis