title: Attenuation of the suppressive activity of cellular splicing factor SRSF3 by Kaposi sarcoma-associated herpesvirus ORF57 protein is required for RNA splicing.
abstract: Kaposi sarcoma-associated herpesvirus (KSHV) ORF57 is a multifunctional post-transcriptional regulator essential for viral gene expression during KSHV lytic infection. ORF57 requires interactions with various cellular proteins for its function. Here, we identified serine/arginine-rich splicing factor 3 (SRSF3, formerly known as SRp20) as a cellular cofactor involved in ORF57-mediated splicing of KSHV K8β RNA. In the absence of ORF57, SRSF3 binds to a suboptimal K8β intron and inhibits K8β splicing. Knockdown of SRSF3 promotes K8β splicing, mimicking the effect of ORF57. The N-terminal half of ORF57 binds to the RNA recognition motif of SRSF3, which prevents SRSF3 from associating with the K8β intron RNA and therefore attenuates the suppressive effect of SRSF3 on K8β splicing. ORF57 also promotes splicing of heterologous non-KSHV transcripts that are negatively regulated by SRSF3, indicating that the effect of ORF57 on SRSF3 activity is independent of RNA target. SPEN proteins, previously identified as ORF57-interacting partners, suppress ORF57 splicing activity by displacing ORF57 from SRSF3-RNA complexes. In summary, we have identified modulation of SRSF3 activity as the molecular mechanism by which ORF57 promotes RNA splicing.
authors.affiliation: Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Majerciak
authors.affiliation: Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
authors.forename: Mathew
authors.initials: M
authors.lastname: Lu
authors.affiliation: Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
authors.forename: Xiaofan
authors.initials: X
authors.lastname: Li
authors.affiliation: Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA zhengt@exchange.nih.gov.
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Zheng
mesh_terms: D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics; D001665:Binding Sites; D057809:HEK293 Cells; D006367:HeLa Cells; D019288:Herpesvirus 8, Human / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007438:Introns; D012326:RNA Splicing; D012367:RNA, Viral / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics; D000068103:Serine-Arginine Splicing Factors; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; C118265:K8 protein, Human herpesvirus 8; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C491388:SRSF3 protein, human; D014764:Viral Proteins; D000068103:Serine-Arginine Splicing Factors
keywords: KSHV; ORF57; RNA processing; SRSF3; alternative splicing