title: The BMP pathway acts to directly regulate Tbx20 in the developing heart.
abstract: TBX20 has been shown to be essential for vertebrate heart development. Mutations within the TBX20 coding region are associated with human congenital heart disease, and the loss of Tbx20 in a wide variety of model systems leads to cardiac defects and eventually heart failure. Despite the crucial role of TBX20 in a range of cardiac cellular processes, the signal transduction pathways that act upstream of Tbx20 remain unknown. Here, we have identified and characterized a conserved 334 bp Tbx20 cardiac regulatory element that is directly activated by the BMP/SMAD1 signaling pathway. We demonstrate that this element is both necessary and sufficient to drive cardiac-specific expression of Tbx20 in Xenopus, and that blocking SMAD1 signaling in vivo specifically abolishes transcription of Tbx20, but not that of other cardiac factors, such as Tbx5 and MHC, in the developing heart. We further demonstrate that activation of Tbx20 by SMAD1 is mediated by a set of novel, non-canonical, high-affinity SMAD-binding sites located within this regulatory element and that phospho-SMAD1 directly binds a non-canonical SMAD1 site in vivo. Finally, we show that these non-canonical sites are necessary and sufficient for Tbx20 expression in Xenopus, and that reporter constructs containing these sites are expressed in a cardiac-specific manner in zebrafish and mouse. Collectively, our findings define Tbx20 as a direct transcriptional target of the BMP/SMAD1 signaling pathway during cardiac maturation.
authors.affiliation: University of North Carolina McAllister Heart Institute, UNC-Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Mandel
authors.forename: Erin
authors.initials: E
authors.lastname: Kaltenbrun
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Callis
authors.forename: Xin-Xin I
authors.initials: XX
authors.lastname: Zeng
authors.forename: Sara R
authors.initials: SR
authors.lastname: Marques
authors.forename: Deborah
authors.initials: D
authors.lastname: Yelon
authors.forename: Da-Zhi
authors.initials: DZ
authors.lastname: Wang
authors.forename: Frank L
authors.initials: FL
authors.lastname: Conlon
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites; D019485:Bone Morphogenetic Proteins / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D006321:Heart / Q000196:embryology*; D006801:Humans; D051379:Mice; D009206:Myocardium / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000378:metabolism*; D014981:Xenopus / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D017931:DNA Primers; D051785:Smad Proteins; D020825:T-Box Domain Proteins
references.citation: Development. 2007 Nov;134(22):4119-30
references.pmid: 17928416
references.citation: J Cell Biochem. 2008 Jun 1;104(3):1022-33
references.pmid: 18275040
references.citation: Cell. 2001 Jun 29;105(7):851-62
references.pmid: 11439182
references.citation: J Biol Chem. 2009 Mar 13;284(11):7149-56
references.pmid: 18684712
references.citation: J Biol Chem. 2000 Jul 21;275(29):21827-35
references.pmid: 10791953
references.citation: Cardiovasc Res. 2007 May 1;74(2):244-55
references.pmid: 17187766
references.citation: Cardiovasc Res. 2006 Jan;69(1):15-25
references.pmid: 16107248
references.citation: Mech Dev. 2000 Mar 1;91(1-2):259-70
references.pmid: 10704850
references.citation: J Mol Cell Cardiol. 2003 Dec;35(12):1407-20
references.pmid: 14654367
references.citation: Curr Opin Genet Dev. 1998 Feb;8(1):103-11
references.pmid: 9529613
references.citation: Development. 2001 Mar;128(6):849-58
references.pmid: 11222140
references.citation: Mech Dev. 2000 Aug;96(1):137-40
references.pmid: 10940636
references.citation: Curr Opin Cardiol. 2004 May;19(3):201-4
references.pmid: 15096950
references.citation: Mech Dev. 2000 Jul;95(1-2):253-8
references.pmid: 10906473
references.citation: Dev Biol. 2002 Apr 15;244(2):243-56
references.pmid: 11944934
references.citation: Ann Med. 2002;34(3):148-56
references.pmid: 12173684
references.citation: EMBO J. 2000 Oct 2;19(19):5178-93
references.pmid: 11013220
references.citation: Nat Chem Biol. 2008 Jan;4(1):33-41
references.pmid: 18026094
references.citation: Genes Dev. 2005 Dec 1;19(23):2783-810
references.pmid: 16322555
references.citation: Dev Biol. 2009 Apr 15;328(2):472-82
references.pmid: 19232521
references.citation: Hum Mol Genet. 2003 Apr 1;12 Spec No 1:R37-44
references.pmid: 12668595
references.citation: Circ Res. 2005 Nov 11;97(10):992-1000
references.pmid: 16224060
references.citation: Development. 1996 Oct;122(10):3173-83
references.pmid: 8898230
references.citation: Dev Biol. 2002 Apr 15;244(2):257-66
references.pmid: 11944935
references.citation: Mol Cell Biol. 2004 Oct;24(19):8519-28
references.pmid: 15367672
references.citation: Bioessays. 1998 Jan;20(1):9-19
references.pmid: 9504043
references.citation: Eur J Med Genet. 2008 Nov-Dec;51(6):580-7
references.pmid: 18834961
references.citation: Dev Dyn. 2006 Jun;235(6):1623-30
references.pmid: 16477648
references.citation: Pediatr Cardiol. 2009 Jul;30(5):609-16
references.pmid: 19099173
references.citation: Birth Defects Res C Embryo Today. 2003 Feb;69(1):25-37
references.pmid: 12768655
references.citation: Circ Res. 2009 Aug 28;105(5):442-52
references.pmid: 19661464
references.citation: Proc Natl Acad Sci U S A. 2008 Dec 16;105(50):19833-8
references.pmid: 19074289
references.citation: Development. 2006 Jul;133(13):2575-84
references.pmid: 16728474
references.citation: Nat Protoc. 2006;1(3):1297-305
references.pmid: 17406414
references.citation: Neuropharmacology. 2004 Jul;47(1):106-16
references.pmid: 15165838
references.citation: Dev Dyn. 2005 Jan;232(1):11-20
references.pmid: 15580613
references.citation: Dev Genes Evol. 2001 Dec;211(11):559-62
references.pmid: 11862462
references.citation: Dev Dyn. 2004 Jan;229(1):201-18
references.pmid: 14699590
references.citation: Dev Dyn. 2009 Jun;238(6):1422-32
references.pmid: 19334278
references.citation: Development. 1999 Oct;126(19):4187-92
references.pmid: 10477287
references.citation: Circ Res. 1996 Feb;78(2):188-95
references.pmid: 8575061
references.citation: Dev Genes Evol. 2003 Jan;212(12):604-7
references.pmid: 12536325
references.citation: Dev Biol. 2000 Feb 15;218(2):235-47
references.pmid: 10656766
references.citation: Genes Dev. 1997 Feb 15;11(4):451-62
references.pmid: 9042859
references.citation: Development. 2001 Mar;128(6):859-69
references.pmid: 11222141
references.citation: J Biol Chem. 2001 May 18;276(20):17206-12
references.pmid: 11278806
references.citation: Mech Dev. 2001 Jan;100(1):87-91
references.pmid: 11118890
references.citation: Am J Hum Genet. 2007 Aug;81(2):280-91
references.pmid: 17668378
references.citation: Development. 2005 Nov;132(22):4897-910
references.pmid: 16258075
references.citation: Nature. 1996 Jun 13;381(6583):620-3
references.pmid: 8637600
references.citation: PLoS One. 2008 Aug 06;3(8):e2904
references.pmid: 18682835