Determining the role of poly [ADP-ribose] polymerase 1 (PARP-1) in retroviral infection
Possible links between PARP-1 and HIV-1 have been previously reported but the role of this protein during viral infection has remained elusive. Based on the high evolutionary conservation of PARP-1, from Drosophila to humans, we have been able to counteract the difficulties related with the functional redundancy manifested in the PARP family by studying the influence of PARP-1 on the expression of an endogenous retrovirus using the chicken B lymphoblastoid cell line DT40, this cell line exhibits low PARP-1 functional redundancy and is viable after PARP-1 knockout. We have determined that the transcription level of the endogenous retrovirus RAV-1 is significantly higher in PARP-1 KO cells than in PARP-1 WT cells but the WT phenotype is restored when PARP-1 KO cells are engineered to re-express human PARP-1 (PARP-1 h-1 cells). Such results suggest that PARP-1 is a cell factor with a negative influence in retroviral transcription and led us to investigate the role of this protein in HIV replication within human cells. Using PARP-1 KD and control human CD4+ T cell lines we have been able to demonstrate that PARP-1 deficiency enhances the replication of the HIV-1. The effect of PARP-1 deficiency in HIV-1 replication in human cells was observed upon pharmacological inhibition of PARP-1. Importantly, inhibitors targeting the zinc finger domains of PARP-1, implicated in DNA binding, but not those inhibiting its catalytic activity caused an enhancement of HIV replication. These results highlight the relevance of the DNA binding domain of PARP-1 in this effect on HIV-1 replication. Intriguingly, in contrast to its effect on HIV-1 replication, PARP-1 antagonism was not affected by a single-round of infection with an HIV-1 lentiviral vector. These replication incompetent viruses only recapitulate the early events of the viral life cycle, leading us to suggest that PARP-1 does not play a role during the early stages of the HIV life cycle. Considering that primary CD4+ T cells are the natural target of the HIV-1 virus, we finally decided to study the role of PARP-1 in HIV-1 replication in these cells. The use of PARP-1 inhibitors and a novel cell model to study HIV latency, allowed us to conclude that in primary cells the presence of PARP-1 negatively modulates HIV-1 replication. This finding implies that PARP-1 could be a restriction factor for HIV replication in human cells. Our data indicates the possibility of using PARP-1 as a new point of therapeutic intervention against the HIV virus in humans.
Valdes, Luis, "Determining the role of poly [ADP-ribose] polymerase 1 (PARP-1) in retroviral infection" (2016). ETD Collection for University of Texas, El Paso. AAI10118192.