SMAD-mediated modulation of YY1 activity regulates the BMP response and cardiac-specific expression of a GATA4/5/6-dependent chick Nkx2.5 enhancer.
Prior work has indicated that BMP signals act in concert with FGF8, WNT11 and WNT antagonists to induce the formation of cardiac tissue in the vertebrate embryo. In an effort to understand how these signaling pathways control the expression of key cardiac regulators, we have characterized the cis-regulatory elements of the chick tinman homolog chick Nkx2.5. We find that at least three distinct cardiac activating regions (CARs) of chick Nkx2.5 cooperate to regulate early expression in the cardiac crescent and later segmental expression in the developing heart. In this report, we focus our attention on a 3' BMP-responsive enhancer, termed CAR3, which directs robust cardiac transgene expression. By systematic mutagenesis and gel shift analysis of this enhancer, we demonstrate that GATA4/5/6, YY1 and SMAD1/4 are all necessary for BMP-mediated induction and heart-specific expression of CAR3. Adjacent YY1 and SMAD-binding sites within CAR3 constitute a minimal BMP response element, and interaction of SMAD1/4 with the N terminus of YY1 is required for BMP-mediated induction of CAR3. Our data suggest that BMP-mediated activation of this regulatory region reflects both the induction of GATA genes by BMP signals, as well as modulation of the transcriptional activity of YY1 by direct interaction of this transcription factor with BMP-activated SMADs.
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue Boston, MA 02115, USA.
Kyu-Ho
KH
Lee
Samuel
S
Evans
Todd Y
TY
Ruan
Andrew B
AB
Lassar
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002642:Chick Embryo; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D050981:Erythroid-Specific DNA-Binding Factors; D050991:GATA4 Transcription Factor; D050992:GATA5 Transcription Factor; D050993:GATA6 Transcription Factor; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009206:Myocardium / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D051785:Smad Proteins; D051898:Smad1 Protein; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D050986:YY1 Transcription Factor
D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050991:GATA4 Transcription Factor; D050992:GATA5 Transcription Factor; D050993:GATA6 Transcription Factor; C494756:Gata5 protein, mouse; D018398:Homeodomain Proteins; D051785:Smad Proteins; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C494699:Yy1 protein, mouse; D004247:DNA