DENGUE VIRUS TARGETS THE RNA-BINDING PROTEIN RBM10 DEREGULATING HOST CELL SPLICING AND INNATE IMMUNE RESPONSE

TORTI, M FLORENCIA; GARCIA, CYBELE; POZZI BERTA; GAIOLI, NICOLAS; GARCÍA SOLÁ ME; SREBROW, ANABELLA

Cold Spring Harbor

Congreso; EUKARYOTIC mRNA PROCESSING; 2019

Cold Spring Harbor Laboratory

Dengue virus is a highly prevalent human pathogen transmitted by insects, mainly Aedes aegypti and Aedes albopictus mosquitoes. This virus presents a positive-sense and single-stranded RNA genome that encodes for a limited set of proteins, relying on the host cell machinery for productive replication. It is known that during infection, viral components subvert cellular processes, remodeling intracellular membranes, changing host metabolic routes and blocking innate antiviral responses.Few years ago, in collaboration with the Gamarnik laboratory, we reported a link between dengue infection and host cell splicing machinery. In RNA- seq experiments using human cells infected with dengue, we observed an enrichment of intronic sequences and changes in alternative splicing patterns. In particular, we noted that the transcript of SAT1 gene, of well- known antiviral action, evidences higher inclusion of alternative exon 4 in infected cells. This exon 4-containing SAT1 mRNA isoform is targeted for degradation by non-sense mediated decay, whereas the exon 4-lacking variant codes for a spermidine/spermine acetyl-transferase enzyme that decreases the reservoir of these polyamines in the cell, limiting viral replication. Delving into the molecular mechanism responsible for this alternative splicing change in SAT1 pre-mRNA upon viral infection, we found lower protein levels of RBM10, a splicing factor responsible for SAT1 exon 4 skipping. We found that the dengue polymerase NS5 interacts with RMB10 and is responsible for RBM10 degradation as it solely over- expression reduces RBM10 protein levels in a proteasome-dependent manner. Actually, RBM10 over-expression in infected cells prevents SAT1 splicing change, while knock-down of this splicing factor not only enhances the splicing change but also benefit viral replication, revealing an anti-viral role for RBM10. In this respect, RBM10 depletion attenuates expression of interferon and pro-inflammatory cytokines. Furthermore, we propose that RBM10 involvement within RIG-I/viral RNA ribonucleoprotein complex, evidenced by co-immunoprecipitation experiments, may account for these RMB10 pro-inflammatory, anti-viral tasks, besides its already well- documented role in splicing regulation of apoptotic genes.