title: Functional association of human Ki-1/57 with pre-mRNA splicing events.
abstract: The cytoplasmic and nuclear protein Ki-1/57 was first identified in malignant cells from Hodgkin's lymphoma. Despite studies showing its phosphorylation, arginine methylation, and interaction with several regulatory proteins, the functional role of Ki-1/57 in human cells remains to be determined. Here, we investigated the relationship of Ki-1/57 with RNA functions. Through immunoprecipitation assays, we verified the association of Ki-1/57 with the endogenous splicing proteins hnRNPQ and SFRS9 in HeLa cell extracts. We also found that recombinant Ki-1/57 was able to bind to a poly-U RNA probe in electrophoretic mobility shift assays. In a classic splicing test, we showed that Ki-1/57 can modify the splicing site selection of the adenoviral E1A minigene in a dose-dependent manner. Further confocal and fluorescence microscopy analysis revealed the localization of enhanced green fluorescent proteinKi-1/57 to nuclear bodies involved in RNA processing and or small nuclear ribonucleoprotein assembly, depending on the cellular methylation status and its N-terminal region. In summary, our findings suggest that Ki-1/57 is probably involved in cellular events related to RNA functions, such as pre-mRNA splicing.
authors.affiliation: Laboratório Nacional de Luz Síncrotron, Campinas, SP, Brasil.
authors.forename: Gustavo C
authors.initials: GC
authors.lastname: Bressan
authors.forename: Alexandre J C
authors.initials: AJ
authors.lastname: Quaresma
authors.forename: Eduardo C
authors.initials: EC
authors.lastname: Moraes
authors.forename: Adriana O
authors.initials: AO
authors.lastname: Manfiolli
authors.forename: Dario O
authors.initials: DO
authors.lastname: Passos
authors.forename: Marcelo D
authors.initials: MD
authors.lastname: Gomes
authors.forename: Jörg
authors.initials: J
authors.lastname: Kobarg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018006:Myogenic Regulatory Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors
chemical_list: C500946:HABP4 protein, human; D018006:Myogenic Regulatory Factors; D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D012313:RNA