Poly(ADP-Ribose) Polymerase 1 Promotes Transcriptional Repression of Integrated Retroviruses

• DOI: 10.1128/jvi.01668-12
• Publication Date: 2012-12-20T10:12:43Z
• Authors: Murilo T. D. Bueno; Daniel Reyes; Luis Valdes; Adarsh Saheba; Eduardo Urias; Crystal Mendoza; Oliver I. Fregoso; Manuel Llano
• Keywords: Gene Expression Regulation, Viral; 0301 basic medicine; Avian Leukosis Virus; Transcription, Genetic; Virus Integration; Poly (ADP-Ribose) Polymerase-1; Virus Replication; Vesicular stomatitis Indiana virus; Cell Line; 3. Good health; Leukemia Virus, Murine; Gene Knockout Techniques; Jurkat Cells; 03 medical and health sciences; HEK293 Cells; Retroviridae; HIV-1; Animals; Humans; Poly(ADP-ribose) Polymerases; Chickens

ABSTRACT

Poly(ADP-ribose) polymerase 1 (PARP-1) is a cellular enzyme with a fundamental role in DNA repair and the regulation of chromatin structure, processes involved in the cellular response to retroviral DNA integration. However, the function of PARP-1 in retroviral DNA integration is controversial, probably due to the functional redundancy of the PARP family in mammalian cells. We evaluated the function of PARP-1 in retroviral infection using the chicken B lymphoblastoid cell line DT40. These cells lack significant PARP-1 functional redundancy and efficiently support the postentry early events of the mammalian-retrovirus replication cycle. We observed that DT40 PARP-1 −/− cells were 9- and 6-fold more susceptible to infection by human immunodeficiency virus type 1 (HIV-1)- and murine leukemia virus (MLV)-derived viral vectors, respectively, than cells expressing PARP-1. Production of avian Rous-associated virus type 1 was also impaired by PARP-1. However, the susceptibilities of these cell lines to infection by the nonretrovirus vesicular stomatitis virus were indistinguishable. Real-time PCR analysis of the HIV-1 life cycle demonstrated that PARP-1 did not impair reverse transcription, nuclear import of the preintegration complex, or viral DNA integration, suggesting that PARP-1 regulates a postintegration step. In support of this hypothesis, pharmacological inhibition of the epigenetic mechanism of transcriptional silencing increased retroviral expression in PARP-1-expressing cells, suppressing the differences observed. Further analysis of the implicated molecular mechanism indicated that PARP-1-mediated retroviral silencing requires the C-terminal region, but not the enzymatic activity, of the protein. In sum, our data indicate a novel role of PARP-1 in the transcriptional repression of integrated retroviruses.