Identification of Three NFAT Binding Motifs in the 5′-Upstream Region of the Human CD3γ Gene That Differentially Bind NFATc1, NFATc2, and NF-κB p50

• Published in: The Journal of biological chemistry 2002-12, Vol.277 (49), p.47136
• Main Authors: Bassam M. Badran, Steven M. Wolinsky, Arsène Burny, Karen E. Willard-Gallo
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M206330200

Human immunodeficiency virus, type 1 (HIV-1) infection of CD4 + T cells progressively abrogates T cell receptor (TCR)·CD3 function and surface expression by specifically interfering with CD3 γ gene transcription. Our data show that the loss of CD3 γ transcripts begins very early after infection and accumulates to a >90% deficiency before a significant effect on surface receptor density is apparent. Blocking TCR·CD3-directed NFAT activation with cyclosporin A provokes a partial re-expression of CD3 γ gene transcripts and surface complexes in a time- and dose-dependent manner. We have identified three NFAT consensus sequences (5′-GGAAA-3′) in the 5′-upstream region of the human CD3 γ gene at: −124 to −120 (NFAT γ1 ), −384 to −380 (NFAT γ2 ), and +450 to +454 (NFAT γ3 ) from the first transcription initiation site. Using electrophoretic mobility shift and supershift assays, we show that NFATc2 alone binds to the NFAT γ2 motif; however, complexes containing either NFATc2 or NFATc1 plus NF-κB p50 bind to the NFAT γ1 and NFAT γ3 sites. We further demonstrate that NFATc1 and NF-κB p50 bind in the same protein·DNA complex and that a fourth Ala added to the core sequence (5′-GGAAA A -3′) in NFAT γ1 , and NFAT γ3 is critical for their binding. Finally, we have shown that an increase in the binding of nuclear NFATc2, NFATc1, and NF-κB p50 to these three motifs is correlated with a progressive loss of CD3 γ transcripts after HIV-1 infection.