Cooperative Interaction between HIV-1 Regulatory Proteins Tat and Vpr Modulates Transcription of the Viral Genome

Abstract

The virion-associated protein of human immunodeficiency virus, type 1 (HIV-1), Vpr, is a small protein with 96 amino acid residues that has the ability to modulate transcription of HIV-1 long terminal repeat (LTR) promoter activity and affects several cellular functions. In this study we have employed molecular approaches to further investigate the mechanism by which Vpr exerts its regulatory effect upon the LTR. We show that by structural and functional interaction with Tat

Molecular mimicry in inducing DNA damage between HIV-1 Vpr and the anticancer agent, cisplatin

“…Next, we examined whether Vpr D(37-50) possesses the ability to cause cell cycle arrest at the G 2 /M checkpoint (Goh et al, 1998) and methods (Sawaya et al, 2000). The cells transfected with expression vectors encoding wt Vpr exhibited cell cycle arrest in the G 2 /M (58.7%) of the cell cycle.…”

“…The pcDNA 3 -Vpr full length and its deletion mutants, EGFPSpectrin, EGFP-Vpr and HIV-LTR-CAT constructs were described previously (Sawaya et al, 1998(Sawaya et al, , 1999(Sawaya et al, , 2000. The human astrocytic cell line, U-87MG, was maintained in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal calf serum (FCS) and supplemented with antibiotics.…”

p27SJ, a novel protein in St John's Wort, that suppresses expression of HIV-1 genome

“…Expression plasmid CMV-HA-Tat has been previously described. 22 HIV-LTR deletion mutants (À476/+66) were generated by PCR amplification of specific regions of the LTR and cloned into HindIII-KpnI in pGL3-basic vector (Promega Corp., Madison, WI, USA). The sequence of all plasmids was verified by DNA sequencing using an ABI automatic sequencer.…”

HIV-1 Tat increases cell survival in response to cisplatin by stimulating Rad51 gene expression

“…After preparation of the recombinant viral particle according to the manufacturer's instructions, PC12 cells (obtained from ATCC, Bethesda, MD, USA) were infected and cells were selected in a medium containing 0.8 mg/ml of G418 and maintained in a medium containing 0.2 mg/ml of G418. The presence of functional Tat is shown by Luciferase assay upon transfection of Tat-negative (PC12) and Tat-positive (PC12-Tat) cells with 0.5 mg of reporter LTR-Luciferase plasmid (Sawaya et al, 2000). (c) Cell survival assay was performed by treatment of the cells with 3 mg/ml of cisplatin for 4 h. Cells were harvested at various times post-treatment and the number of viable cells was assessed by Trypan blue staining.…”