Nuclear factor of activated T cells 2 transactivation in mast cells: a novel isoform-specific transactivation domain confers unique FcepsilonRI responsiveness.
Murine nuclear factor of activated T cells (NFAT)2.alpha/beta differ by 42 and 28 unique amino-terminal amino acids and are differentially expressed. Both isoforms share conserved domains that regulate DNA-binding and subcellular localization. A genetic "one-hybrid" assay was used to define two distinct transactivation (TA) domains: in addition to a conserved TAD present in both isoforms, a second, novel TAD exists within the beta-specific amino terminus. Pharmacologic inhibitors Gö6976 and rottlerin demonstrate that both conventional and novel protein kinase C (PKC) family members regulate endogenous mast cell NFAT activity, and NFAT2 TA. Overexpression of dominant active PKC (which has been implicated in immune receptor signaling) induces NFAT2.alpha/beta TA. Mutations within the smallest PKC-responsive transactivation domain demonstrate that the PKC effect is at least partially indirect. Significantly, the beta-specific domain confers greater ability to TA in response to treatment with phorbol 12-myristate 13-acetate/ionomycin or lipopolysaccharide, and unique sensitivity to FcepsilonRI signaling. Accordingly, overexpression of NFAT2.beta results in significantly greater NFAT- and interleukin-4 reporter activity than NFAT2.alpha. These results suggest that whereas NFAT2 isoforms may share redundant DNA-binding preferences, there are specialized functional consequences of their isoform-specific domains.
Department of Pathology and Graduate Program in Genetics and Molecular Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
M Benjamin
MB
Hock
Melissa A
MA
Brown
D000098:Acetophenones / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001578:Benzopyrans / Q000494:pharmacology; D001665:Binding Sites / Q000235:genetics; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D008407:Mast Cells / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051745:Protein Kinase C-delta; D017434:Protein Structure, Tertiary; D017455:Receptors, IgE / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D020798:Two-Hybrid System Techniques
D000098:Acetophenones; D001578:Benzopyrans; D002227:Carbazoles; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007211:Indoles; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D009687:Nuclear Proteins; D020033:Protein Isoforms; D017455:Receptors, IgE; D011994:Recombinant Proteins; D014157:Transcription Factors; C081021:Go 6976; D015759:Ionomycin; D004247:DNA; C085746:rottlerin; C497259:Prkcd protein, mouse; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D013755:Tetradecanoylphorbol Acetate