Role of Puralpha in the modulation of homologous recombination-directed DNA repair by HIV-1 Tat.
BACKGROUND
The nucleic acid-binding protein Puralpha is involved at stalled DNA replication forks, in double-strand break (DSB) DNA repair and the cellular response to DNA replication stress. Puralpha interacts with HIV-1 Tat, which regulates homologous recombination-directed DNA repair (HRR).


METHODS
We investigated Rad51 and HRR regulation in mouse embryo fibroblasts (MEFs) from PURA -/- knockout mice that lack Puralpha.


RESULTS
Rad51 was induced in PURA -/- MEFs but was repressed when Puralpha was ectopically expressed in these cells. Similarly Rad51 inversely correlated with the level of Puralpha in normal postnatal mouse brain. HIV-1 Tat stimulated HRR DNA repair of I-SceI induced DNA DSBs and the nuclear appearance of Rad51 foci. In contrast, Puralpha suppressed HRR DNA repair, Rad51 expression, and Rad51 foci formation.


CONCLUSIONS
Tat stimulates the Rad51 promoter involving both Puralpha-dependent and Puralpha-independent mechanisms. Interaction between Puralpha and Tat may have opposing effects on Rad51 expression. The effects on HRR may contribute to HIV-1 associated pathogenesis.
Wang
Huichen
H
Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, PA 19122, USA.
White
Martyn K
MK
Kaminski
Rafal
R
Darbinian
Nune
N
Amini
Shohreh
S
Johnson
Edward M
EM
Khalili
Kamel
K
Rappaport
Jay
J
D000818:Animals; D001253:Astrocytes / Q000502:physiology; D002478:Cells, Cultured; D004260:DNA Repair / Q000235:genetics*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics*; D005347:Fibroblasts / Q000502:physiology; D015497:HIV-1; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051135:Rad51 Recombinase / Q000096:biosynthesis / Q000235:genetics; D011995:Recombination, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000235:genetics*
D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; C121485:Pura protein, mouse; D054322:tat Gene Products, Human Immunodeficiency Virus; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse