Differential contribution of NFATc2 and NFATc1 to TNF-alpha gene expression in T cells.
The NFAT family transcription factors play crucial roles in immunological and other biological events; however, the functional differences among NFAT members have not been fully elucidated. This study investigated the relative contribution of NFATc2 and NFATc1 to the transactivation of cytokine genes in T cells. Ectopic expression of NFATc2 but not NFATc1, especially its short isoform, enhanced TNF-alpha synthesis in human T cells at the gene transcription level, whereas both NFATs augmented IL-2 expression. In addition, a reduction of the shortest NFATc1 isoform using RNA interference technology failed to suppress TNF-alpha expression. The promoter/enhancer activity of the NFAT-binding site in the TNF-alpha gene was up-regulated by NFATc2 but not by NFATc1, whereas both NFATs associated similarly with this region. A study of mRNA expression using NFATc2/NFATc1 chimeric molecules revealed that the enhancing activity of NFAT on the TNF-alpha gene was lost by truncation of its C-terminal transactivation domain. In addition, this domain derived from NFATc2 behaved as a dominant negative against the NFAT site in TNF-alpha promoter-dependent transcriptional activity in T cells. We conclude that the C-terminal transactivation domain in NFAT is crucial for TNF-alpha gene expression in human T cells.
Kaminuma
Osamu
O
Cytokine Project, Department of Allergy and Immunology, The Tokyo Metropolitan Institute of Medical Science, Japan. kaminuma@rinshoken.or.jp
Kitamura
Fujiko
F
Kitamura
Noriko
N
Hiroi
Takachika
T
Miyoshi
Hiroyuki
H
Miyawaki
Atsushi
A
Miyatake
Shoichiro
S
D002460:Cell Line; D016207:Cytokines / Q000235:genetics; D004742:Enhancer Elements, Genetic; D015870:Gene Expression; D006801:Humans; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D016207:Cytokines; D050778:NFATC Transcription Factors; C494003:NFATC1 protein, human; C494006:NFATC2 protein, human; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha