Characterization of a new isoform of the NFAT (nuclear factor of activated T cells) gene family member NFATc.
The cyclosporin A (CsA)/FK506-sensitive nuclear factor of activated T cells (NFAT) plays a key role in the inducible expression of cytokine genes in T cells. Although NFAT has been recently shown to be inducible in several non-T immune cells, the NFAT gene family members characterized to date have been isolated only from T cells. To further characterize NFAT function in human B cells and to demonstrate cytokine gene specificity of NFAT proteins, we report here the isolation and characterization of a cDNA clone from the Raji B cell line. The cDNA clone encodes a new isoform, NFATc.beta, of the NFAT gene family member NFATc (designated here NFATc.alpha). The amino acid sequence of NFATc.beta differs from that of NFATc. alpha in the first NH2-terminal 29 residues and contains an additional region of 142 residues at the COOH terminus. Northern analysis using a probe encompassing a common region of both isoforms showed two mRNA species of 2.7 and 4.5 kilobase pairs, while an NFATc.beta-specific probe detected only the 4.5-kilobase pair mRNA which was preferentially expressed in the spleen. Transient expression of NFATc.beta was capable of activating an interleukin-2 NFAT-driven reporter gene in stimulated Jurkat cells in a CsA-sensitive manner. However, NFATc.beta neither bound to the kappa3 element (an NFAT-binding site) in the tumor necrosis factor-alpha promoter nor activated the tumor necrosis factor-alpha promoter in cotransfection assays. These data suggest that different members or isoforms of NFAT gene family may regulate inducible expression of different cytokine genes.
Park
J
J
Department of Pathology, Roger Williams Medical Center-Brown University, Providence, Rhode Island 02908, USA.
Takeuchi
A
A
Sharma
S
S
D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D002051:Burkitt Lymphoma; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000145:classification / Q000235:genetics*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D050778:NFATC Transcription Factors; C494003:NFATC1 protein, human; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha