The regulation of HIV-1 replication by the transcription factors USF1, USF2, and TFII-I (RBF-2)

Despite efforts to eliminate the HIV-1 virus from infected individuals, the virus persists in a latent chromosomally integrated pool of provirus that evades current drug therapy. Upon cessation of highly active anti-retroviral therapy (HAART), the latent virus begins to replicate resulting in an increased viral titre in the patient's serum, leading to Acquired Immune Deficiency Syndrome (AIDS). A great amount of effort has gone into determining the mechanisms involved in the establishment of viral latency, in order to find targets that can be used in combination with existing therapies to eradicate the virus. In this thesis, I characterize a protein complex that is required for viral replication of integrated virus and therefore has potential as a therapeutic target. The data presented in this thesis identify USF1, USF2, and TFII-I as the proteins that comprise the Ras-response element Binding Factor-2 (RBF-2), which binds constitutively to the Ras-response Factor Binding Elements I and III (RBEI and RBEIII) within the Long Terminal Repeat (LTR) promoter. RBEIII is highly conserved in sequence and position relative to the transcriptional start site. In addition, both RBEIII and RBEI are situated near nucleosomes in the LTR enhancer region. Furthermore, I provide evidence that RBF-2 proteins are modified by phosphorylation in response to T-cell activation. Finally, I demonstrate that mutations in RBEIII that prevent the binding of these factors, as measured by electrophoretic mobility shifting assays, also prevent HIV-1 activation, as observed from stably integrated reporter virus.Medicine, Faculty ofBiochemistry and Molecular Biology, Department ofGraduat