Certain lung injuries induce large increases in connective tissue content, particularly collagen, resulting in fibrosis. During injury, cells are exposed to molecules such as interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta), regulating production of matrix components. Clinical trials for interstitial pulmonary fibrosis (IPF) are ongoing. However, very little is understood concerning collagen repression by this mediator. This project focuses on establishing the mechanisms by which collagen transcription is repressed by IFN- gamma. We have recently described a regulatory factor for X-box (RFX) binding site at the collagen transcription start site. RFX1 represses collagen transcription. RFX1 interacts with and activates c-Abl, a non- receptor tyrosine kinase that can phosphorylate itself, RFX1 and the carboxyl domain of RNA polymerase II (CTD). C-Abl interacts with RFX1 at the collagen transcription start site. This proposal determines whether c-Abl participates in signal transduction pathways leading to decreased collagen synthesis. RFX5 forms a complex at the collagen transcription start site when RFX1 is removed. IFN-gamma induces class II transcription activator (CIITA) which interacts with RFX5 forming a complex with two other proteins that activate major histocompatibility class II proteins (MHC-II). Since IFN-gamma represses collagen synthesis, we hypothesize that RFX proteins mediate collagen transcription repression during IFN-gamma treatment. Our overall hypothesis is that IFN-gamma repression occurs on the collagen promoter by cooperative interactions of RFX protein family members at the start site with other proteins binding to the proximal promoter.
The specific aims are to; 1) Determine the function and interactions of RFX family before and after IFN-gamma treatment. 2) Examine the functional interactions of c-Abl with RFX proteins at the collagen transcription start site. 3) Examine the localization and kinase activity of c-Abl and RFX in lung fibroblasts under different treatments and in samples of human lung tissue. 4) Use transgenic animals with collagen-promoter-CAT constructs or animals deficient in c-Abl or RFX5 complex to investigate collagen transcriptional regulation during fibrosis and treatment.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL068094-02
Application #
6538076
Study Section
Lung Biology and Pathology Study Section (LBPA)
Program Officer
Reynolds, Herbert Y
Project Start
2001-07-01
Project End
2005-05-31
Budget Start
2002-06-01
Budget End
2003-05-31
Support Year
2
Fiscal Year
2002
Total Cost
$326,000
Indirect Cost
Name
Boston University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
604483045
City
Boston
State
MA
Country
United States
Zip Code
02118
Xu, Yong; Luchsinger, Larry; Lucey, Edgar C et al. (2011) The effect of class II transactivator mutations on bleomycin-induced lung inflammation and fibrosis. Am J Respir Cell Mol Biol 44:898-905
Luchsinger, Larry L; Patenaude, Cassandra A; Smith, Barbara D et al. (2011) Myocardin-related transcription factor-A complexes activate type I collagen expression in lung fibroblasts. J Biol Chem 286:44116-25
Wu, Xiaoyan; Kong, Xiaocen; Luchsinger, Larry et al. (2009) Regulating the activity of class II transactivator by posttranslational modifications: exploring the possibilities. Mol Cell Biol 29:5639-44
Xu, Yong; Ravid, Katya; Smith, Barbara D (2008) Major histocompatibility class II transactivator expression in smooth muscle cells from A2b adenosine receptor knock-out mice: cross-talk between the adenosine and interferon-gamma signaling. J Biol Chem 283:14213-20
Xu, Yong; Harton, Jonathan A; Smith, Barbara D (2008) CIITA mediates interferon-gamma repression of collagen transcription through phosphorylation-dependent interactions with co-repressor molecules. J Biol Chem 283:1243-56
Xu, Yong; Farmer, Stephen R; Smith, Barbara D (2007) Peroxisome proliferator-activated receptor gamma interacts with CIITA x RFX5 complex to repress type I collagen gene expression. J Biol Chem 282:26046-56
Xu, Yong; McDonald, Jessica; Perloff, Emily et al. (2007) Collagen and major histocompatibility class II expression in mesenchymal cells from CIITA hypomorphic mice. Mol Immunol 44:1709-21
Xu, Yong; Sengupta, Pritam K; Seto, Edward et al. (2006) Regulatory factor for X-box family proteins differentially interact with histone deacetylases to repress collagen alpha2(I) gene (COL1A2) expression. J Biol Chem 281:9260-70
Buttice, Giovanna; Miller, Janice; Wang, Lin et al. (2006) Interferon-gamma induces major histocompatibility class II transactivator (CIITA), which mediates collagen repression and major histocompatibility class II activation by human aortic smooth muscle cells. Circ Res 98:472-9
Sengupta, Pritam; Xu, Yong; Wang, Lin et al. (2005) Collagen alpha1(I) gene (COL1A1) is repressed by RFX family. J Biol Chem 280:21004-14

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