Background. It has been estimated that 20-30% of HIV-infected individuals develop HIV dementia. It has been reported that gp120 is able to cause death of human neuroblastome (NB) cells and being the direct cause of neurotoxicity. Moreover, recent results support a role of cyclooxigenase-2 (COX-2) in HIV-1 dementia. Due the importance of COX-2 expression in neuronal apoptosis, we have studied the molecular mechanism by which gp120 controls COX-2 expression in NB cells. Methods. To study the COX-2 gp120 induction in NB cells we have used SK-N-MC cells. COX-2 mRNA and protein were measured by quantitative RT-PCR and by Western-Blot and immunofluorescence respectively. We studied the COX-2 promoter-driven transcription in transiently transfected SK-N-MC cells using a promoter containing the transcription start site of the human COX-2 gene in the reporter plasmid pXP2 (P2-1900). We analyzed the involvement of NFAT, NF-kB and AP-1 in this regulation, and so we performed cotransfections with the P1900 construct plus several expression plasmids encoding a deletion mutant of a murine constitutively active calcineurin catalytic subunit (DCAM-AI), or a dominant negative of NFAT (dn-NFAT), and the p65 protein, or the inhibitory subunit IkB-a; also we analyzed the effect of a dominant negative mutant of c-Jun. Results. Our data show that gp120 induces COX-2 mRNA and protein in SK-N-MC cells. Moreover, gp120 was able to increase COX-2 promoter activity in the NB cell line tested. The dn c-Jun adn IkBa overexpression, suppressed the transcriptional activity of COX-2 promoter, overexpression of the p65 factor induced transcriptional activity of p2-1900 analyzed by the reporter gene assay. Cotransfection experiments of P2-1900 plus DCAM-AI did not result in an induction of transcriptional activity of COX-2, in the same way, cotransfection with dn-NFAT did not inhibit the activity of promoter. Conclusions. Gp120 enhances COX-2 promoter activity and protein expression in NB cells assigning a predominant role to NF-kB and AP-1 factors sites in this regulation.
Keywords: AEGIS, Prostaglandin-Endoperoxide Synthase, Isoenzymes, cdc42 GTP-Binding Protein, Promoter Regions (Genetics), Nuclear Proteins, NF-kappa B, Proto-Oncogene Proteins c-jun, Transcription Factor AP-1, Transcription, Genetic, I-kappa B, Calcineurin, Cell Cycle Proteins, RNA, Messenger, Apoptosis, cyclooxygenase 2, NBS1 protein, human, Humans, genetics
