Project Grant R01AI177341

REGULATION OF HSV LATENCY BY POLYCOMB SILENCING - PROJECT SUMMARY/ABSTRACT REACTIVATION OF VIRUSES FROM LATENT INFECTION CAN RESULT IN SERIES DISEASE. IN ADDITION, LATENT INFECTIONS ARE A BARRIER TO CURING CERTAIN VIRAL DISEASES. FOR THE PERSISTENT HERPESVIRUS, HERPES SIMPLEX VIRUS (HSV), THE MECHANISMS THAT REGULATE ENTRY OF THE VIRUS INTO A LATENT INFECTION ARE NOT KNOWN. THE FORMATION OF HETEROCHROMATIN ON THE VIRAL GENOME IN NEURONS HAS LONG BEEN HYPOTHESIZED TO CONTRIBUTE TO SUPPRESSING GENE EXPRESSION FOR LATENCY ESTABLISHMENT. HOWEVER, NO FUNCTIONAL STUDIES HAVE YET IDENTIFIED A ROLE FOR HETEROCHROMATIN FORMATION AS A MECHANISM TO PROMOTE ENTRY INTO LATENCY OR MAINTAIN A LATENT INFECTION. THERE ARE MULTIPLE DIFFERENT TYPES OF HETEROCHROMATIN, WHICH DIFFER THEIR MECHANISMS OF GENE SILENCING AND ABILITY TO BE REVERSED FOR GENE EXPRESSION TO TAKE PLACE. OUR OVERALL HYPOTHESIS IS THAT HSV ACTIVELY PROMOTES A TYPE OF HETEROCHROMATIN TO ENABLE BOTH PERSISTENCE AND REACTIVATION. OUR DATA INDICATE THAT THE HISTONE MODIFICATION, H2AK119UB1, IS ENRICHED ON THE HSV GENOME DURING LATENCY. H2AK119UB1 FUNCTIONS TO REPRESS GENE EXPRESSION, BUT IT IS ALSO KNOWN TO BE RAPIDLY REMODELED TO PERMIT GENE EXPRESSION TO TAKE PLACE IN RESPONSE TO CERTAIN STIMULI. IMPORTANTLY, OUR PRELIMINARY DATA INDICATE THAT H2AK119UB1 NEEDS TO BE DEPOSITED ONTO HSV GENOMES TO LATER ENABLE REACTIVATION TO OCCUR. TO UNDERSTAND THE CONTRIBUTION OF H2AK119UB1 TO HSV LATENCY AND REACTIVATION, ALONG WITH THE MECHANISM OF H2AK119UB1 DEPOSITION ON THE GENOME, COMPLEMENTARY IN VITRO AND IN VIVO MODELS OF HSV LATENCY ARE ESSENTIAL. OUR LAB HAS DEVELOPED NOVEL IN VITRO MODEL SYSTEMS TO INVESTIGATE THE MOLECULAR MECHANISMS OF HSV LATENCY ESTABLISHMENT AND REACTIVATION, WHICH WE COMBINE WITH HIGH-RESOLUTION IMAGING TO INVESTIGATE THE ASSOCIATION OF INDIVIDUAL VIRAL GENOMES WITH CHROMATIN-ASSOCIATED PROTEINS. THESE ASSAYS WILL BE COMPLEMENTED WITH EPIGENETIC ASSAYS TO MAP AND QUANTIFY PROTEIN ASSOCIATION WITH VIRAL GENOMES IN VITRO AND IN VIVO. IN AIM 1, WE WILL INVESTIGATE HOW H2AK119UB1 IMPACTS THE ESTABLISHMENT OF LATENCY. IN AIM 2, WE WILL DETERMINE HOW THE PROTEIN COMPLEX RESPONSIBLE FOR H2AK119UB1 IS RECRUITED TO VIRAL GENOMES VIA INTERACTING WITH THE HSV LONG NON-CODING RNA KNOWN AS THE LATENCY ASSOCIATED TRANSCRIPT. IN AIM 3, WE WILL EXAMINE WHY H2AK119UB1 ASSOCIATION IS REQUIRED FOR THE FORMATION OF REACTIVATION COMPETENT LATENT INFECTION. UPON COMPLETION OF THESE AIMS, WE WILL UNDERSTAND HOW HETEROCHROMATIN IS TARGETED TO THE HSV GENOME TO LIMIT LYTIC GENE EXPRESSION SPECIFICALLY IN NEURONS AND THEREFORE PROMOTE LATENCY ESTABLISHMENT. WE WILL ANSWER A LONG-STANDING QUESTION ON THE MECHANISTIC FUNCTION OF THE LATENCY ASSOCIATED TRANSCRIPT IN REGULATING LATENCY ESTABLISHMENT AND REACTIVATION. FINALLY, WE WILL UNDERSTAND HOW DIFFERENT TYPES OF HETEROCHROMATIN MODULATE THE ABILITY OF HSV TO UNDERGO REACTIVATION. ULTIMATELY, WE WILL IDENTIFY TARGETS FOR THERAPEUTICS THAT COULD ACT TO DIRECTLY PREVENT LATENCY ESTABLISHMENT OR REACTIVATION, OR MODULATE THE LATENT EPIGENETIC STRUCTURE INTO A FORM THAT IS NON-PERMISSIVE FOR REACTIVATION.