• BMB Reports
• /
• v.55 no.12
• /
• pp.639-644
• /
• 2022

Serine-arginine-rich splicing factors (SRSFs) are members of RNA processing proteins in the serine-arginine-rich (SR) family that could regulate the alternative splicing of the human immunodeficiency virus-1 (HIV-1). Whether SRSF9 has any effect on HIV-1 regulation requires elucidation. Here, we report for the first time the effects and mechanisms of SRSF9 on HIV-1 regulation. The overexpression of SRSF9 inhibits viral production and infectivity in both HEK293T and MT-4 cells. Deletion analysis of SRSF9 determined that the RNA regulation motif domain of SRSF9 is important for anti-HIV-1 effects. Furthermore, overexpression of SRSF9 increases multiple spliced forms of viral mRNA, such as Vpr mRNA. These data suggest that SRSF9 overexpression inhibits HIV-1 production by inducing the imbalanced HIV-1 mRNA splicing that could be exploited further for a novel HIV-1 therapeutic molecule.

• BMB Reports
• /
• v.49 no.11
• /
• pp.612-616
• /
• 2016

CD44 pre-mRNA includes 20 exons, of which exons 1-5 ($C_1-C_5$) and exons 16-20 ($C_6-C_{10}$) are constant exons, whereas exons 6-15 ($V_1-V_{10}$) are variant exons. $V_6$-exon-containing isoforms have been known to be implicated in tumor cell invasion and metastasis. In the present study, we performed a SR protein screen for CD44 $V_6$ splicing using overexpression and lentivirus-mediated shRNA treatment. Using a CD44 $V_6$ minigene, we demonstrate that increased SRSF3 and SRSF4 expression do not affect $V_6$ splicing, but increased expression of SRSF1, SRSF6 and SRSF9 significantly inhibit $V_6$ splicing. In addition, using a constitutive exon-specific primer set, we could not detect alterations of CD44 splicing after SR protein-targeting shRNA treatment. However, using a $V_6$ specific primer, we identified that reduced SRSF2 expression significantly reduced the $V_6$ isoform, but increased $V_{6-10}$ and $V_{6,8-10}$ isoforms. Our results indicate that SR proteins are important regulatory proteins for CD44 $V_6$ splicing.