Functional association of human Ki-1/57 with pre-mRNA splicing events.
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.
Bressan
Gustavo C
GC
Laboratório Nacional de Luz Síncrotron, Campinas, SP, Brasil.
Quaresma
Alexandre J C
AJ
Moraes
Eduardo C
EC
Manfiolli
Adriana O
AO
Passos
Dario O
DO
Gomes
Marcelo D
MD
Kobarg
Jörg
J
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
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