title: Modulation of protein translation by Nck-1.
abstract: In mammals, Nck represented by two genes, is a 47-kDa SH2/SH3 domain-containing protein lacking intrinsic enzymatic function. Here, we reported that the first and the third SH3 domains of Nck-1 interact with the C-terminal region of the beta subunit of the eukaryotic initiation factor 2 (eIF2 beta). Binding of eIF2 beta was specific to the SH3 domains of Nck-1, and in vivo, the interaction Nck/eIF2 beta was demonstrated by reciprocal coimmunoprecipitations. In addition, Nck was detected in a molecular complex with eIF2 beta in an enriched ribosomal fraction, whereas no other SH2/SH3 domain-containing adapters were found. Cell fractionation studies demonstrated that the presence of Nck in purified ribosomal fractions was enhanced after insulin stimulation, suggesting that growth factors dynamically regulate translocation of Nck to ribosomes. In HEK293 cells, we observed that transient overexpression of Nck-1 significantly enhanced Cap-dependent and -independent protein translation. This effect of Nck-1 required the integrity of its first and third SH3 domains originally found to interact with eIF2 beta. Finally, in vitro, Nck-1 also increased protein translation, revealing a direct role for Nck-1 in this process. Our study demonstrates that in addition to mediate receptor tyrosine kinase signaling, Nck-1 modulates protein translation potentially through its direct interaction with an intrinsic component of the protein translation machinery.
authors.affiliation: Departments of Medicine and Surgery, Polypeptide Laboratory, Division of Endocrinology, McGill University, Montreal, QC, Canada H3A 2B2.
authors.forename: Sem
authors.initials: S
authors.lastname: Kebache
authors.forename: Dongmei
authors.initials: D
authors.lastname: Zuo
authors.forename: Eric
authors.initials: E
authors.lastname: Chevet
authors.forename: Louise
authors.initials: L
authors.lastname: Larose
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D015723:Gene Library; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D015513:Oncogene Proteins / Q000737:chemistry* / Q000502:physiology*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry; D013347:Subcellular Fractions; D013395:Sucrose / Q000494:pharmacology; D014018:Tissue Distribution; D014158:Transcription, Genetic; D014162:Transfection; D020798:Two-Hybrid System Techniques; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018076:DNA, Complementary; D015852:Eukaryotic Initiation Factor-2; D007328:Insulin; C078332:Nck protein; D015513:Oncogene Proteins; D011993:Recombinant Fusion Proteins; D013395:Sucrose; D008156:Luciferases; D011972:Receptor, Insulin