title: Mitotic phosphorylation of eukaryotic initiation factor 4G1 (eIF4G1) at Ser1232 by Cdk1:cyclin B inhibits eIF4A helicase complex binding with RNA.
abstract: During mitosis, global translation is suppressed, while synthesis of proteins with vital mitotic roles must go on. Prior evidence suggests that the mitotic translation shift involves control of initiation. Yet, no signals specifically targeting translation initiation factors during mitosis have been identified. We used phosphoproteomics to investigate the central translation initiation scaffold and "ribosome adaptor," eukaryotic initiation factor 4G1 (eIF4G1) in interphase or nocodazole-arrested mitotic cells. This approach and kinase inhibition assays, in vitro phosphorylation with recombinant kinase, and kinase depletion-reconstitution experiments revealed that Ser1232 in eIF4G1 is phosphorylated by cyclin-dependent kinase 1 (Cdk1):cyclin B during mitosis. Ser1232 is located in an unstructured region of the C-terminal portion of eIF4G1 that coordinates assembly of the eIF4G/-4A/-4B helicase complex and binding of the mitogen-activated protein kinase (MAPK) signal-integrating kinase, Mnk. Intense phosphorylation of Ser1232 in mitosis strongly enhanced the interactions of eIF4A with HEAT domain 2 of eIF4G and decreased association of eIF4G/-4A with RNA. Our findings implicate phosphorylation of eIF4G1(Ser1232) by Cdk1:cyclin B and its inhibitory effects on eIF4A helicase activity in the mitotic translation initiation shift.
authors.affiliation: Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA.
authors.forename: Mikhail I
authors.initials: MI
authors.lastname: Dobrikov
authors.forename: Mayya
authors.initials: M
authors.lastname: Shveygert
authors.forename: Michael C
authors.initials: MC
authors.lastname: Brown
authors.forename: Matthias
authors.initials: M
authors.lastname: Gromeier
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D056744:Cyclin B1 / Q000235:genetics / Q000378:metabolism*; D039601:Eukaryotic Initiation Factor-4A / Q000235:genetics / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D007399:Interphase / Q000187:drug effects / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects / Q000235:genetics; D009154:Mutation; D015739:Nocodazole / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000235:genetics / Q000378:metabolism; D013936:Thymidine / Q000494:pharmacology; D050257:Tubulin Modulators / Q000494:pharmacology
chemical_list: D056744:Cyclin B1; C113920:EIF4G1 protein, human; D039603:Eukaryotic Initiation Factor-4G; D047908:Intracellular Signaling Peptides and Proteins; D050257:Tubulin Modulators; C502582:aminopurvalanol A; D012694:Serine; D012313:RNA; C491395:MKNK1 protein, human; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D039601:Eukaryotic Initiation Factor-4A; D000225:Adenine; D015739:Nocodazole; D013936:Thymidine