Peptide growth factors, such as the Transforming Growth Factor beta (TGFbeta) family, play central roles in morphogenesis and organogenesis. The narrowly defined vertebrate TGFbeta family is composed of at least three 25 kilodalton homodimeric proteins, TGFbeta1, TGFbeta2, and TGFbeta3. TGFbeta1 and TGFbeta 3 share identical ligand binding and biological activities while TGFbeta2 has a unique requirement for the Type III TGFbeta receptor (TBRIII) and distinct biological activities. We have recently demonstrated a requirement for TBRIII in TGFbeta-mediated epithelial-mesenchymal cell transformation that occurs in the atrioventricular (AV) cushion of the developing heart. We are testing the hypothesis that a unique receptor signal transduction complex is responsible for AV cushion transformation. Since current models of TGFbeta signal transduction presuppose a requirement for a Type I receptor (TBRI) in the signal transduction complex, initial experiments will determine if a Type I receptor (TBRI) is a component of the receptor complex in the AV cushion. Specifically, we will determine whether the ALK2 or ALK5 TBRI is required for transformation. This will be determined both by misexpression of constituitively active ALK2 and ALK5 and antisense constructs. A well described pathway for downstream signal transduction from TGFbeta receptors includes the Smads family of transcription factors. We will test the hypothesis that specific Smads are necessary for AV cushion transformation by , determining if dominate negative inhibitors of Smads or constitutively active Smads alter transformation in AV cushion explants and ventricular explants. Preliminary data in our laboratory suggests a role for the ALK2, and not ALK5, in transformation. Therefore we will test the hypothesis that ALK2 associates with TBRIII to mediate transformation by immunoprecipitation of the TGFbeta receptor complex and identification of ALK2 and ALK5. We also will immunolocalize TBRI and TBRIII on both chick embryonic fibroblasts and AV cushion endothelial cells to determine whether they associate after the addition of TGFbeta. These experiments are part of a concerted strategy to determine whether TBRIII requires a TBRI and downstream Smad signaling. Our long-term goal to understand the role of TGFbeta in cushion transformation and the genesis of congenital heart defects due to abnormal cushion transformation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL052922-10
Application #
6822626
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Schramm, Charlene A
Project Start
1996-03-20
Project End
2006-11-30
Budget Start
2004-12-01
Budget End
2006-11-30
Support Year
10
Fiscal Year
2005
Total Cost
$347,300
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Pharmacology
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Kirkbride, Kellye C; Townsend, Todd A; Bruinsma, Monique W et al. (2008) Bone morphogenetic proteins signal through the transforming growth factor-beta type III receptor. J Biol Chem 283:7628-37
Townsend, Todd A; Wrana, Jeffrey L; Davis, George E et al. (2008) Transforming growth factor-beta-stimulated endocardial cell transformation is dependent on Par6c regulation of RhoA. J Biol Chem 283:13834-41
Olivey, Harold E; Mundell, Nathan A; Austin, Anita F et al. (2006) Transforming growth factor-beta stimulates epithelial-mesenchymal transformation in the proepicardium. Dev Dyn 235:50-9
Park, Ho-Jin; Ward, Simone M; Desgrosellier, Jay S et al. (2006) Transforming growth factor beta regulates the expression of the M2 muscarinic receptor in atrial myocytes via an effect on RhoA and p190RhoGAP. J Biol Chem 281:19995-20002
Compton, Leigh A; Potash, Dru A; Mundell, Nathan A et al. (2006) Transforming growth factor-beta induces loss of epithelial character and smooth muscle cell differentiation in epicardial cells. Dev Dyn 235:82-93
Desgrosellier, Jay S; Mundell, Nathan A; McDonnell, Maureen A et al. (2005) Activin receptor-like kinase 2 and Smad6 regulate epithelial-mesenchymal transformation during cardiac valve formation. Dev Biol 280:201-10
Barnett, Joey V; Desgrosellier, Jay S (2003) Early events in valvulogenesis: a signaling perspective. Birth Defects Res C Embryo Today 69:58-72
Olivey, Harold E; Barnett, Joey V; Ridley, Bettye D (2003) Expression of the type III TGFbeta receptor during chick organogenesis. Anat Rec A Discov Mol Cell Evol Biol 272:383-7
Marlow, Michael S; Brown, Christopher B; Barnett, Joey V et al. (2003) Solution structure of the chick TGFbeta type II receptor ligand-binding domain. J Mol Biol 326:989-97
Ward, Simone M; Desgrosellier, Jay S; Zhuang, Xiaoli et al. (2002) Transforming growth factor beta (TGFbeta ) signaling via differential activation of activin receptor-like kinases 2 and 5 during cardiac development. Role in regulating parasympathetic responsiveness. J Biol Chem 277:50183-9

Showing the most recent 10 out of 16 publications