Ribosomal Frameshifting in HIV-1 Infection, Inflammation and Neurotoxicity

ABSTRACT Human immunodeficiency virus (HIV-1) infection can lead to Acquired Immune Deficiency Syndrome (AIDS) and HIV-Associated Neurocognitive Disorder (HAND). In the life cycle of HIV-1, programmed ribosomal frameshifting (PRF) is a key event during translation of HIV-1 mRNA that allows the synthesis of viral enzymes. While the cis- acting RNA elements for HIV-1 PRF have been well defined, the trans-acting viral and cellular factors regulating HIV-1 PRF remain relatively unexplored, which constitutes a knowledge gap in HIV-1 research. We have performed a genome wide CRISPR knockout screen to identify host factors that regulate HIV-1 PRF. Our screen has revealed that m1acp3Ψ modification of rRNA, wybutosine (yW) modification of tRNAPhe, and diphthamide (DPH) modification of eEF2 are major trans-acting factors that repress ribosomal frameshifting on HIV-1 mRNA. These modifications (m1acp3Ψ, yW, and DPH) are of central importance to the accuracy of cellular protein synthesis. Individuals with deficiency of yW or DPH modification present with neurodevelopmental disorders and intellectual disability. We have also found that yW modification of tRNAPhe and DPH modification of eEF2 are blocked in HIV-1 infected cells. Our central hypothesis is that HIV-1 upregulates ribosomal frameshifting by depletion of yW and DPH to facilitate virus replication, while increased ribosomal frameshifting promotes HIV-1 inflammation and neurotoxicity. In this project, we will elucidate the mechanism by which HIV-1 downregulates yW and DPH modifications (Aim 1), determine the roles of yW, DPH, and m1acp3Ψ in HIV-1 PRF and replication (Aim 2), and determine the roles of yW and DPH in HIV-1 inflammation and neurotoxicity (Aim 3). Our proposed studies will significantly improve our understanding of the molecular mechanism of HIV-1 PRF and provide new insight into HIV-1 pathogenesis. In the long term, these studies will provide new targets and strategies for the treatment of HIV-1 infection.