Induction of monocyte chemoattractant protein-1 (MCP-1/CCL2) gene expression by human immunodeficiency virus-1 Tat in human astrocytes is CDK9 dependent.
Human immunodeficiency virus-1 (HIV-1) invades the brain early in infection and may cause HIV-associated dementia (HAD), which is characterized by reactive astrocytes, and macrophage and T-cell infiltrates. HIV-1 Tat protein is thought to contribute to HAD by transactivating host genes, such as that encoding monocyte chemoattractant protein-1 (MCP-1/CCL2), although its mechanisms of action are not fully understood. We investigated the molecular pathways involved in Tat-induced MCP-1/CCL2 gene expression in human astrocytes. We found that Tat induced MCP-1/CCL2 synthesis in human astrocytes infected with a lentivirus carrying the gene encoding Tat or treated with a biologically active synthetic Tat protein. The induction of MCP-1/CCL2 was independent of the nuclear factor kappaB (NF-kappaB) classical pathway, but was significantly inhibited by specific cyclin-dependent kinase 9 (cdk9) inhibitors, such as a dominant-negative mutant or siRNA. By contrast, broader-spectrum cdk inhibitors, such as roscovitine, 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole (DRB), and flavopiridol, inhibited MCP-1/CCL2 induction by Tat. We also analyzed the effects of roscovitine, DRB, and flavopiridol on Tat-induced HIV-1 long terminal repeat (LTR) expression following the infection of astrocytes and HeLa cells. Astrocytes showed no inhibition by roscovitine, 59% inhibition by DRB, and 80% inhibition by flavopiridol. In control HeLa cells, high levels of inhibition were observed with roscovitine, DRB, and flavopiridol. We have ascertained the direct implication of cdk9 in Tat-induced MCP-1 expression by performing ChIP assay. These results demonstrate that cdk9 is involved in Tat-induced HIV-1 LTR, MCP-1/CCL2 gene expression.
Khiati
Abdelkader
A
INSERM U802 and Université Paris-Sud 11, Faculté de médecine Paris-Sud, Le Kremlin-Bicêtre, France.
Chaloin
Olivier
O
Muller
Sylviane
S
Tardieu
Marc
M
Horellou
Philippe
P
D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism* / Q000821:virology*; D015153:Blotting, Western; D002469:Cell Separation; D018932:Chemokine CCL2 / Q000096:biosynthesis* / Q000235:genetics; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D016325:HIV Long Terminal Repeat / Q000187:drug effects / Q000235:genetics; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D034741:RNA, Small Interfering; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics*; D014162:Transfection; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D054322:tat Gene Products, Human Immunodeficiency Virus; D042863:Cyclin-Dependent Kinase 9