The latent TGF-beta binding protein-1 (LTBP-1) is a 120-170 kD molecule with strong homology to fibrillins-1 and -2; the proteins defective in Marfan syndrome and Congenital Contractual Arachnodactyly. LTBP-1 has 18 EGF-like repeats, most of which are Ca++-binding, and 4 repeats of a cysteine-rich domain. Fibrillins-1 and -2 contain over 40 EGF-like repeats and seven cysteine-rich domains. Thus far, 2 cysteine-rich domains have only been described in the LTBPs and fibrillins. Consistent with the widespread in vivo distribution of LTBP-1, in vitro experiments indicate that LTBP-1 is required for TGF-beta release from its latent complex, is necessary for bone nodule differentiation, and is critical for epithelial-mesenchymal transformation during endocardial cushion formation. Thus, LTBP-1 may carry out duel functions. It may be important in matrix organization, and/or it may target latent TGF- beta to sites where subsequent release regulates normal tissue maturation. However, the mechanisms and consequences of LTBP-1 activity in matrix organization and/or in TGF-beta function in vivo have not been elaborated and the differentiation of LTBP-1 activity as either a matrix structural component or as a latent TGF-beta targeting molecule has not been described. We will analyze these possibilities using a genetic approach whereby mice will be developed that express either 1) TGF-beta1 modified so that the cysteine required for bonding to LTBP-1 is mutated to serine, thereby blocking TGF-beta1 interaction with LTBP-1, or 2) LTBP-1 either missing specific sequences necessary for fibrillogenesis or with a null mutation. The phenotypes of animals expressing these mutated proteins will be analyzed, and cells and tissues derived from these mice will be characterized by histologic and functional assays to analyze fibrillogenesis, TGF-beta activation, bone nodule formation, and endocardial-mesenchymal transformation. Studies with mice expressing the TGF-beta mutation should clarify the relationship between LTBP-1 binding and TGF-beta activation and indicate the importance of matrix bound latent TGF-beta. Studies with mutated LTBP-1 should elucidate the role of LTBP-1 in the organization of connective tissue and may reveal a phenotype to suggest a role for LTBP-1 in human disease. The information gained from these studies will reveal the function of LTBP-1 and improve our understanding of tissue organization and growth factor action in both normal and pathological states including cancer, cardiovascular malformation, and bone formation.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA078422-05
Application #
6628152
Study Section
Pathobiochemistry Study Section (PBC)
Program Officer
Ault, Grace S
Project Start
1999-04-01
Project End
2004-01-31
Budget Start
2003-02-01
Budget End
2004-01-31
Support Year
5
Fiscal Year
2003
Total Cost
$377,203
Indirect Cost
Name
New York University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
121911077
City
New York
State
NY
Country
United States
Zip Code
10016
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Chen, Yan; Ali, Tariq; Todorovic, Vesna et al. (2005) Amino acid requirements for formation of the TGF-beta-latent TGF-beta binding protein complexes. J Mol Biol 345:175-86
Colarossi, Cristina; Chen, Yan; Obata, Hiroto et al. (2005) Lung alveolar septation defects in Ltbp-3-null mice. Am J Pathol 167:419-28
Mazzieri, Roberta; Jurukovski, Vladimir; Obata, Hiroto et al. (2005) Expression of truncated latent TGF-beta-binding protein modulates TGF-beta signaling. J Cell Sci 118:2177-87
Fontana, Laura; Chen, Yan; Prijatelj, Petra et al. (2005) Fibronectin is required for integrin alphavbeta6-mediated activation of latent TGF-beta complexes containing LTBP-1. FASEB J 19:1798-808
Annes, Justin; Vassallo, Melinda; Munger, John S et al. (2004) A genetic screen to identify latent transforming growth factor beta activators. Anal Biochem 327:45-54
Ramirez, Francesco; Sakai, Lynn Y; Dietz, Harry C et al. (2004) Fibrillin microfibrils: multipurpose extracellular networks in organismal physiology. Physiol Genomics 19:151-4
Annes, Justin P; Chen, Yan; Munger, John S et al. (2004) Integrin alphaVbeta6-mediated activation of latent TGF-beta requires the latent TGF-beta binding protein-1. J Cell Biol 165:723-34
Krishnan, Suba; Deora, Arunkumar B; Annes, Justin P et al. (2004) Annexin II-mediated plasmin generation activates TGF-beta3 during epithelial-mesenchymal transformation in the developing avian heart. Dev Biol 265:140-54
Annes, Justin P; Munger, John S; Rifkin, Daniel B (2003) Making sense of latent TGFbeta activation. J Cell Sci 116:217-24

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