title: The translation initiation factor 3 subunit eIF3K interacts with PML and associates with PML nuclear bodies.
abstract: The promyelocytic leukemia protein (PML) is a tumor suppressor protein that regulates a variety of important cellular processes, including gene expression, DNA repair and cell fate decisions. Integral to its function is the ability of PML to form nuclear bodies (NBs) that serve as hubs for the interaction and modification of over 90 cellular proteins. There are seven canonical isoforms of PML, which encode diverse C-termini generated by alternative pre-mRNA splicing. Recruitment of specific cellular proteins to PML NBs is mediated by protein-protein interactions with individual PML isoforms. Using a yeast two-hybrid screen employing peptide sequences unique to PML isoform I (PML-I), we identified an interaction with the eukaryotic initiation factor 3 subunit K (eIF3K), and in the process identified a novel eIF3K isoform, which we term eIF3K-2. We further demonstrate that eIF3K and PML interact both in vitro via pull-down assays, as well as in vivo within human cells by co-immunoprecipitation and co-immunofluorescence. In addition, eIF3K isoform 2 (eIF3K-2) colocalizes to PML bodies, particularly those enriched in PML-I, while eIF3K isoform 1 associates poorly with PML NBs. Thus, we report eIF3K as the first known subunit of the eIF3 translation pre-initiation complex to interact directly with the PML protein, and provide data implicating alternative splicing of both PML and eIF3K as a possible regulatory mechanism for eIF3K localization at PML NBs.
authors.affiliation: Department of Pathology, Dalhousie University, P.O. Box 15000, Halifax, Nova Scotia, Canada B3H 4R2.
authors.forename: Jayme
authors.initials: J
authors.lastname: Salsman
authors.forename: Jordan
authors.initials: J
authors.lastname: Pinder
authors.forename: Brenda
authors.initials: B
authors.lastname: Tse
authors.forename: Dale
authors.initials: D
authors.lastname: Corkery
authors.forename: Graham
authors.initials: G
authors.lastname: Dellaire
mesh_terms: D017398:Alternative Splicing; D022003:Cell Nucleus Structures / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000071156:Promyelocytic Leukemia Protein; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: C468124:EIF3K protein, human; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D020033:Protein Isoforms; D021122:Protein Subunits; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human
keywords: Light microscopy; Nuclear structure; PML; Yeast two-hybrid; eIF3K