Formation of the cardiac outflow tract is a complex morphogenetic process, whose failure results in a variety of clinically important congenital heart malformations. We have found that the homeodomain transcription factors encoded by the Pbx gene family are required for development of the cardiac outflow tract in mice. Mutations in Pbx genes lead to persistent truncus arteriosus, tetralogy of Fallot, overriding aorta and bicuspid aortic valves. These defects resemble cardiac anomalies observed in chick when neural crest cells are ablated. We hypothesize that Pbx genes are essential for neural crest cell function in mice, and propose to use those mouse models to investigate the mechanisms of how Pbx1 gene regulates neural crest cell function required for cardiac outflow tract development. These studies will provide insights to the developmental mechanisms of congenital heart defects. Specifically, we will study (1) whether Pbx1 acts cell intrinsically within the neural crest cells to regulate their function, (2) whether Pbx1 is essential to program the developmental fates of neural crest cells and (3) the molecular pathways downstream of Pbx1 in cardiac development.
Aim #1 : Determine the cellular sites of Pbx1 action required for cardiac development We will use the genetic Cre-lox methods and several mouse lines that express Ore recombinase in neural crest cells, myocardial cells and endocardial cells to study the cellular sites where Pbx1 may function to regulate the development of cardiac neural crest cells.
Aim #2 : Determine the role of Pbx1 in neural crest cell development. To study if Pbx1 is required for specifying the developmental identities of cardiac neural crest cells, we plan to employ RNA in situ hybridization and rhombomeric differentiation markers to study the rhombomeric identities in Pbx1-/- mouse embryos. As cardiac neural crest cells originate from rhombomeres, expression of rhombomeric markers in the PbxT1'embryos will provide insights to the fate specification of cardiac neural crest cells. Additional markers of neural crest cells will also be used to study the differentiation of neural crest cells as they migrate out of the neural tube.
Aim #3 : Define the molecular pathways affected by the absence of Pbx1. We will use standard molecular biology and embryology methods to study if Pax3 pathway is downstream of Pbx1 in cardiac development.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL085345-04
Application #
7625060
Study Section
Cardiovascular Differentiation and Development Study Section (CDD)
Program Officer
Schramm, Charlene A
Project Start
2006-07-17
Project End
2011-05-31
Budget Start
2009-06-01
Budget End
2010-05-31
Support Year
4
Fiscal Year
2009
Total Cost
$382,941
Indirect Cost
Name
Stanford University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
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Li, Wei; Lin, Chieh-Yu; Shang, Ching et al. (2014) Pbx1 activates Fgf10 in the mesenchyme of developing lungs. Genesis 52:399-407
Wu, Bingruo; Zhang, Zheng; Lui, Wendy et al. (2012) Endocardial cells form the coronary arteries by angiogenesis through myocardial-endocardial VEGF signaling. Cell 151:1083-96
Lin, Chieh-Yu; Lin, Chien-Jung; Chen, Chen-Hao et al. (2012) The secondary heart field is a new site of calcineurin/Nfatc1 signaling for semilunar valve development. J Mol Cell Cardiol 52:1096-102
Koss, Matthew; Bolze, Alexandre; Brendolan, Andrea et al. (2012) Congenital asplenia in mice and humans with mutations in a Pbx/Nkx2-5/p15 module. Dev Cell 22:913-26
Han, Pei; Hang, Calvin T; Yang, Jin et al. (2011) Chromatin remodeling in cardiovascular development and physiology. Circ Res 108:378-96
Hang, Calvin T; Yang, Jin; Han, Pei et al. (2010) Chromatin regulation by Brg1 underlies heart muscle development and disease. Nature 466:62-7
Stankunas, Kryn; Ma, Gene K; Kuhnert, Frank J et al. (2010) VEGF signaling has distinct spatiotemporal roles during heart valve development. Dev Biol 347:325-36
Bajpai, Ruchi; Chen, Denise A; Rada-Iglesias, Alvaro et al. (2010) CHD7 cooperates with PBAF to control multipotent neural crest formation. Nature 463:958-62
Zeini, Miriam; Hang, Calvin T; Lehrer-Graiwer, Joshua et al. (2009) Spatial and temporal regulation of coronary vessel formation by calcineurin-NFAT signaling. Development 136:3335-45

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