Human GM-CSF induces HIV-1 LTR by multiple signalling pathways.
Human immunodeficiency virus type-1 (HIV-1) gene expression is known to be affected by numerous cytokines or growth factors. However, the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on long terminal repeat (LTR)-mediated transcription of HIV-1 still remains unknown. By transient transfection experiments with HIV-1 LTR reporter constructs, we showed that strong LTR-mediated activation was induced by GM-CSF in mouse Ba/F3 cells expressing human GM-CSF receptors (GM-CSFR). Mutational analysis of the HIV-1 LTR reporters revealed that both NF-kappaB and Sp1 binding sites play important roles as positive regulatory elements. Analysis of various mutants of the cytoplasmic region of GM-CSFR indicated that both the conserved membrane proximal region and tyrosine residues located in the distal part of the beta subunit were required for HIV-1 LTR activation. Possible involvement of MAPK and PI3-K signalling pathways was suggested by the partial inhibition by wortmannin, a specific inhibitor of the PI3-K pathway, and enhancement by constitutively active MEK1, of HIV-1 LTR activation. However, the MEK1 pathway is not essential since MEK1 inhibitor PD98059 did not suppress GM-CSF-induced HIV-1-LTR activation. Further analyses of GM-CSFR mutants suggested that some other unknown signalling pathway also participates in GM-CSF-induced HIV-1 LTR activation. Taken together, the data suggest that GM-CSF could upregulate the LTR-driven transcription of HIV-1 through modulation of NF-kappaB and SP1 by multiple signalling pathways.
Watanabe
Sumiko
S
Department of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. sumiko@ims.u-tokyo.ac.jp
Murakami
Tomoe
T
Nakamura
Tetsuya
T
Morimoto
Chikao
C
Arai
Ken-ichi
K
D000818:Animals; D002460:Cell Line; D002999:Clone Cells; D015967:Gene Expression Regulation, Viral; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D016325:HIV Long Terminal Repeat / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010957:Plasmids; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000187:drug effects / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D008156:Luciferases; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011994:Recombinant Proteins; D016329:Sp1 Transcription Factor; D014443:Tyrosine