The cardiac transcription factors Nkx2-5 and GATA-4 are mutual cofactors.
The tissue-restricted GATA-4 transcription factor and Nkx2-5 homeodomain protein are two early markers of precardiac cells. Both are essential for heart formation, but neither can initiate cardiogenesis. Overexpression of GATA-4 or Nkx2-5 enhances cardiac development in committed precursors, suggesting each interacts with a cardiac cofactor. We tested whether GATA-4 and Nkx2-5 are cofactors for each other by using transcription and binding assays with the cardiac atrial natriuretic factor (ANF) promoter_the only known target for Nkx2-5. Co-expression of GATA-4 and Nkx2-5 resulted in synergistic activation of the ANF promoter in heterologous cells. The synergy involves physical Nkx2-5-GATA-4 interaction, seen in vitro and in vivo, which maps to the C-terminal zinc finger of GATA-4 and a C-terminus extension; similarly, a C-terminally extended homeodomain of Nkx2-5 is required for GATA-4 binding. Structure/function studies suggest that binding of GATA-4 to the C-terminus autorepressive domain of Nkx2-5 may induce a conformational change that unmasks Nkx2-5 activation domains. GATA-6 cannot substitute for GATA-4 for interaction with Nkx2-5. This interaction may impart functional specificity to GATA factors and provide cooperative crosstalk between two pathways critical for early cardiogenesis. Given the co-expression of GATA proteins and NK2 class members in other tissues, the GATA/Nkx partnership may represent a paradigm for transcription factor interaction during organogenesis.
Durocher
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D
Laboratoire de Développement et Différenciation Cardiaques, Institut de Recherches Cliniques de Montréal, 110 des Pins Ouest, Montréal Qu-ebec, Canada H2W 1R7.
Charron
F
F
Warren
R
R
Schwartz
R J
RJ
Nemer
M
M
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis* / Q000235:genetics*; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics; D002460:Cell Line; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics; D050991:GATA4 Transcription Factor; D006367:HeLa Cells; D006321:Heart / Q000502:physiology; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D014714:Vertebrates; D029867:Xenopus Proteins
D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; C095552:NKX2-5 protein, human; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; D009320:Atrial Natriuretic Factor