Sandoval, Carina
Carina is in the Gene Regulation, Epigenomics and Transcriptomics home area of MBIDP, and joined the CMB training program in 2019. She received a B.S. degree in Molecular Biology & Biotechnology from California State University, Fullerton.
Mentor: Dr. Oliver Fregoso
Large strides have been made in understanding the basic molecular biology of the Human Immunodeficiency Virus (HIV), which have led to advances in the development and success of antiretroviral therapies. Yet despite this knowledge, there are still many aspects of HIV biology we do not understand. To cure individuals of HIV, we must first understand the molecular mechanisms of viral replication and then develop novel therapies that take advantage of essential steps in the viral lifecycle.
One such aspect of HIV biology that has remained a mystery despite decades of research is the accessory gene Vpr. Vpr is evolutionarily conserved and important for pathogenesis in vivo, yet a clear role for Vpr in viral replication has not been defined. Over the years Vpr has been implicated in various parts of the lifecycle, including reverse transcription, integration, and provirus transcription, however only three functions are conserved among Vpr orthologs: interaction with the E3 ubiquitin ligase complex Cul4ADCAF1, activation of the DNA damage response (DDR), and subsequent ATR-mediated cell cycle arrest. Furthermore, since cell cycle arrest requires ATR, we believe this is a consequence of DDR activation. This suggests that activation of the DDR is the conserved function of Vpr, which enhances viral replication.
Our lab set about determining how Vpr engages with the DDR. We found that both HIV-1 and HIV-2 Vpr form nuclear foci and activate markers of double strand & single strand DNA breaks. This suggests that Vpr either damages DNA to activate DDR markers or Vpr activates DDR markers independent of DNA damage. To determine if Vpr damages DNA we utilized the alkaline comet assay and found that both HIV-1 and HIV-2 Vpr cause DNA breaks. Furthermore, we found that activation of damage is not altered by inhibition of ATR, suggesting Vpr-mediated DNA damage is an early event in Vpr function. Therefore, we hypothesize that Vpr binds specific regions of the genome and induces DNA damage to enhance viral replication by facilitating provirus transcription. To address this hypothesis, we have devised three specific aims that first characterize the DNA damage caused by Vpr, second gain a molecular mechanistic understanding of Vpr-induced DNA damage, and third determine how Vpr enhances viral replication. Together, these aims will help to elucidate the primary conserved function of Vpr.
