Genome wide analysis of hnRNP binding to HIV-1 RNA reveals a key role for hnRNP H1 in alternative viral mRNA splicing

Sebla B. Kutluay, Ann Emery, Srinivas Penumutchu, Dana Townsend, Kasyap Tenneti, Michaela K. Madison, Amanda M. Stukenbroeker, Chelsea Powell, David Jannain, Blanton S. Tolbert, Ronald I. Swanstrom, Paul D. Bieniasz
2019 Journal of Virology  
Alternative splicing of HIV-1 mRNAs increases viral coding potential and controls the levels and timing of gene expression. HIV-1 splicing is regulated in part by heterogeneous nuclear ribonucleoproteins (hnRNPs) and their viral target sequences, that typically repress splicing when studied outside their native viral context. Here, we determined the location and extent of hnRNP binding to HIV-1 mRNAs and their impact on splicing in a native viral context. Notably, hnRNPA1, hnRNPA2 and hnRNPB1
more » ... und to many dispersed sites across viral mRNAs. Conversely, hnRNPH1 bound to a few discrete purine-rich sequences, a finding that was mirrored in vitro. HnRNPH1 depletion and mutation of a prominent viral RNA hnRNPH1 binding site decreased use of splice acceptor A1, causing a deficit in Vif expression and replicative fitness. This quantitative framework for determining the regulatory inputs governing alternative HIV-1 splicing revealed an unexpected splicing enhancer role for hnRNPH1 through binding to its target element. IMPORTANCE Alternative splicing of HIV-1 mRNAs is an essential, yet quite poorly understood step of virus replication that enhances the coding potential of the viral genome and allows temporal regulation of viral gene expression. Although HIV-1 constitutes an important model system for general studies of the regulation of alternative splicing, the inputs that determine the efficiency with which splice sites are utilized remain poorly defined. Our studies provide an experimental framework to study an essential step of HIV-1 replication more comprehensively and in much greater detail than was previously possible and reveal novel cis acting elements regulating HIV-1 splicing.
doi:10.1128/jvi.01048-19 pmid:31413137 pmcid:PMC6803249 fatcat:gj4sgesxqvgsbjl635plwmzhiu