Anti-SRSF1 polyclonal antibody

Background: Human polyomavirus JCV is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease characterized by lytic infection of glial cells in the central nervous system. PML is seen primarily in immunosuppressed patients and is mainly classified as an AIDS-defining disease. In addition to structural capsid proteins, JCV encodes multiple regulatory proteins, including T-antigen and agnoprotein, which are required for functional lytic infection. Previous studies have suggested that molecular interaction between viral proteins and host factors play an important role in reactivation of JCV and progression of the viral life cycle in glial cells. Recently, serine/arginine rich splicing factor 1 (SRSF1), a cellular alternative splicing factor, was identified as a strong negative regulator of JCV in glial cells. SRSF1 inhibits JCV gene expression and viral replication by directly interacting with viral promoter sequences. Here, we have investigated possible impact of JCV regulatory proteins, T-antigen and agnoprotein, on SRSF1-mediated suppression of JCV gene expression in glial cells. Results: Reporter gene analysis has suggested that T-antigen rescues viral transcriptional suppression mediated by SRSF1. Further analyses have revealed that T-antigen promotes viral gene expression by suppressing SRSF1 gene transcription in glial cells. A subsequent ChIP analysis revealed that T-antigen associates with the promoter region of SRSF1 to induce the transcriptional suppression. Conclusions: These findings have revealed a molecular interplay between cellular SRSF1 and viral T-antigen in controlling JCV gene expression, and may suggest a novel mechanism of JCV reactivation in patients who are at risk of developing PML.

Histone deacetylases (HDACs) and lysine acetyltransferases (KATs) catalyze dynamic histone acetylation at regulatory and coding regions of transcribed genes. Highly phosphorylated HDAC2 is recruited within corepressor complexes to regulatory regions, while the nonphosphorylated form is associated with the gene body. In this study, we characterized the nonphosphorylated HDAC2 complexes recruited to the transcribed gene body and explored the function of HDAC-complex-mediated dynamic histone acetylation. HDAC1 and 2 were coimmunoprecipitated with several splicing factors, including serine/arginine-rich splicing factor 1 (SRSF1) which has roles in alternative splicing. The co-chromatin immunoprecipitation of HDAC1/2 and SRSF1 to the gene body was RNA-dependent. Inhibition of HDAC activity and knockdown of HDAC1, HDAC2 or SRSF1 showed that these proteins were involved in alternative splicing of MCL1. HDAC1/2 and KAT2B were associated with nascent pre-mRNA in general and with MCL1 pre-mRNA specifically. Inhibition of HDAC activity increased the occupancy of KAT2B and acetylation of H3 and H4 of the H3K4 methylated alternative MCL1 exon 2 nucleosome. Thus, nonphosphorylated HDAC1/2 is recruited to pre-mRNA by splicing factors to act at the RNA level with KAT2B and other KATs to catalyze dynamic histone acetylation of the MCL1 alternative exon and alter the splicing of MCL1 pre-mRNA.