Human idiopathic pulmonary fibrosis (IPF) is a progressive, lethal fibrotic lung disease characterized by non-resolving epithelial injury, persistent myofibroblast (MFB) phenotype and stiffening of the extracellular matrix (ECM). Biomechanical signals derived from stiff/fibrotic ECM are emerging as crucial factors that regulate fibrotic lung progression. In recent studies, we have demonstrated that RhoA/Rho kinase (ROCK) mediate matrix stiffness sensing by lung MFBs. Inhibition of RhoA/ROCK mechanosensitive signaling ameliorates experimental lung fibrosis. MFBs isolated from patients with IPF are characterized by an invasive phenotype. It is currently not known whether pathologic ECM-derived biomechanical signaling regulates the invasive phenotype of IPF MFBs. Preliminary studies showed that matrix stiffness regulates IPF MFB invasion into the basement membrane (BM) by a RhoA/ROCK-dependent mechanism. Stiff matrix upregulates gene expression of integrin alpha 6 (ITGA6), matrix metalloproteinase 9 (MMP9) and urokinase-type plasminogen activator receptor (uPAR), factors associated with BM binding and degradation. Blocking ITGA6-mediated cell adhesion abrogates stiff matrix-dependent MFB invasion into the BM. Stiff matrix promotes ROCK-dependent phosphorylation of c-Fos and c-Jun, components of activator protein (AP-1) transcription factor complex, and selectively increases c-Fos and c-Jun binding to immobilized oligonucleotides containing AP-1-binding elements (TREs). Bioinformatics identified multiple TREs in the promoter regions of ITGA6, MMP9 and uPAR. These findings suggest that stiff matrix-induced RhoA/ROCK mechanosensitive signaling promotes MFB invasion into the BM by AP-1-dependent activation of an invasive gene program involving ITGA6, MMP9 and uPAR. The preliminary studies together with our previous studies suggest that RhoA/ROCK mechanosensitive signaling activates multiple fibrogenic mechanotransduction pathways through which sustained RhoA/ROCK signaling amplifies epithelial injury-induced lung fibrosis. In this project, we hypothesize that stiff matrix- induced RhoA/ROCK mechanosensitive signaling regulates MFB invasion into the BM and promotes persistent/progressive lung fibrosis.
Specific aims are to: (1) determine whether c-Fos and c-Jun of AP-1 transcription factor complex mediate RhoA/ROCK mechanosensitive signaling to activate invasive gene program; (2) determine whether ITGA6, MMP9 and/or uPAR mediate RhoA/ROCK mechanosensitive signaling to regulate MFB invasion into the BM; and (3) determine whether sustained RhoA/ROCK mechanosensitive signaling following bleomycin-induced lung injury promotes persistent/progressive lung fibrosis in mice. The proposed study, if proven, will provide novel mechanistic insights into the promulgation of invasive MFB phenotype. It will provide proof-of-concept for pathologic ECM-derived biomechanical signaling in the pathogenesis of persistent/progressive fibrosis. The long-term goal of this project is to understand the biomechanical signal mechanisms of lung fibrosis and identify novel targets for effective anti-fibrotic therapies.

Public Health Relevance

Idiopathic pulmonary fibrosis (IPF) is a progressive, lethal fibrotic lung disease with no effective drug therapies. The proposed studies will explore the molecular mechanisms involved in the pathogenesis of persistent/progressive lung fibrosis. The goal of this project is to develop novel therapeutic interventions for effective IPF treatment.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL124076-01A1
Application #
8837161
Study Section
Lung Injury, Repair, and Remodeling Study Section (LIRR)
Program Officer
Harabin, Andrea L
Project Start
2014-12-01
Project End
2018-11-30
Budget Start
2014-12-01
Budget End
2015-11-30
Support Year
1
Fiscal Year
2015
Total Cost
Indirect Cost
Name
University of Alabama Birmingham
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
063690705
City
Birmingham
State
AL
Country
United States
Zip Code
35294
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