RNA binding and phosphorylation determine the intracellular distribution of nuclear factors 90 and 110.
Members of the nuclear factor 90 (NF90) family of human double-stranded RNA (dsRNA) binding proteins are phosphorylated and translocate into the cytoplasm with the onset of mitosis. We investigated the mechanism of translocation for NF90 and NF110, its larger splice variant. During interphase, NF90 is predominantly nuclear, NF110 is exclusively nuclear, and both are bound to RNA. About half of the NF90 is tethered in the nucleus by RNA bound to the protein's dsRNA-binding motifs. The nuclear localization of NF110 is also dependent on RNA binding but is independent of these motifs, and is governed by contacts made to the protein's unique C terminus. During mitosis, about half of the cytoplasmic NF90 becomes dissociated from RNA, but phosphorylation does not impair the binding affinity of either NF90 or NF110 for dsRNA. We conclude that NF90 and NF110 engage RNA differentially and translocate from the nucleus to the cytoplasm in mitosis because phosphorylation disturbs their interactions with other nuclear proteins.
Parrott
Andrew M
AM
Department of Biochemistry and Molecular Biology and New Jersey Medical School, UMDNJ, 185 South Orange Ave., P.O. Box 1709, Newark, NJ 07101-1709, USA.
Walsh
Melissa R
MR
Reichman
Trevor W
TW
Mathews
Michael B
MB
D017398:Alternative Splicing; D002453:Cell Cycle; D002457:Cell Extracts; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D009154:Mutation / Q000235:genetics; D050778:NFATC Transcription Factors; D050779:Nuclear Factor 90 Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D002457:Cell Extracts; D004268:DNA-Binding Proteins; C429643:ILF3 protein, human; D050778:NFATC Transcription Factors; D050779:Nuclear Factor 90 Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D012313:RNA; D003851:Deoxyribonucleases; D012260:Ribonucleases