Long-term goal: To elucidate the cellular and molecular basis of excess scar formation during wound repair. This application will focus on the role of altered expression of plasminogen activator inhibitor-1 (PAI-1) in collagen over-production by keloidfibroblasts. Proteolytic degradation of the provisional fibrin matrix and remodeling of the newly formed collagen-containing scar tissues are essential features in injury repair. Keloids, resulting from improper wound healing, are the extreme form of skin fibrosis with unknown etiology. Using a 3-dimensional fibrin gel culture system, we discovered that keloid fibroblasts are defective in fibrin degradation due to PAl-1 over-expression. In the previous granting period, we established, both in vitro and in vivo, that PAI-1 overexpression is phenotypic of keloid fibroblasts and is causal in the elevated collagen accumulation. Reducing PAI-1 activity also abolishes the elevated collagen accumulation in keloid fibroblasts (Tuan et al., Am J Pathol 2003). In addition, we demonstrated that, in vivo, PAI-1 increases as fetal mouse skin wounds transition from scarless (El5) to scar-forming (E18 and after) repair, and aprotinin, a uPA/plasmin inhibitor, causes scar formation in E15 fetal skin wounds (Huang et al., WRR 2002). PAI-1 is the major inhibitor of the plasminogen activator (PA)/plasmin system. This system is central to fibrin degradation, cell adhesion and migration, and metalloproteinase (MMP) activation, which is essential in collagen turnover. Thus, we hypothesize that """"""""PAl-1 contributes to elevated collagen accumulation in keloid fibroblasts by inhibiting MMP activation and or by modulating uPA-mediated cell adhesion"""""""". PAI-1 is a down stream target of TGF-beta, and keloid fibroblasts exhibit TGF-beta-mediated differences in matrix contraction and collagen synthesis. Thus, we also hypothesize that """"""""an altered TGF-beta signaling pathway and or utilization of PAI-1 promoter response elements are responsible for increased PAI-1 expression in keloidfibroblasts"""""""" The established evidence and the unique experimental models will allow us to test these hypotheses through the following specific aims:
Aim I : To investigate the role of PAI-1 increase in MMP- and cell adhesion-mediated collagen accumulation in keloid fibroblasts.
Aim II : To determine the biological mechanism of PAI-1 increase resulting from altered TGF-beta signaling events and/or difference in PAI-1 promoter utilization in keloid fibroblasts.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM055081-08
Application #
7175404
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Ikeda, Richard A
Project Start
1998-07-01
Project End
2008-01-31
Budget Start
2007-02-01
Budget End
2008-01-31
Support Year
8
Fiscal Year
2007
Total Cost
$275,125
Indirect Cost
Name
Children's Hospital of Los Angeles
Department
Type
DUNS #
052277936
City
Los Angeles
State
CA
Country
United States
Zip Code
90027
Lien, Ching-Ling; Harrison, Michael R; Tuan, Tai-Lan et al. (2012) Heart repair and regeneration: recent insights from zebrafish studies. Wound Repair Regen 20:638-46
Kim, Jieun; Rubin, Nicole; Huang, Ying et al. (2012) In vitro culture of epicardial cells from adult zebrafish heart on a fibrin matrix. Nat Protoc 7:247-55
Lee, Yun-Shain; Wysocki, Annette; Warburton, David et al. (2012) Wound healing in development. Birth Defects Res C Embryo Today 96:213-22
Kim, Jieun; Wu, Qiong; Zhang, Yolanda et al. (2010) PDGF signaling is required for epicardial function and blood vessel formation in regenerating zebrafish hearts. Proc Natl Acad Sci U S A 107:17206-10
Yeh, Jennifer; Green, Lydia M; Jiang, Ting-Xin et al. (2009) Accelerated closure of skin wounds in mice deficient in the homeobox gene Msx2. Wound Repair Regen 17:639-48
Dudas, Marek; Wysocki, Annette; Gelpi, Brian et al. (2008) Memory encoded throughout our bodies: molecular and cellular basis of tissue regeneration. Pediatr Res 63:502-12
Tuan, Tai-Lan; Hwu, Paul; Ho, Wendy et al. (2008) Adenoviral overexpression and small interfering RNA suppression demonstrate that plasminogen activator inhibitor-1 produces elevated collagen accumulation in normal and keloid fibroblasts. Am J Pathol 173:1311-25
Li, Wai-Yee; Huang, Eunice Y; Dudas, Marek et al. (2006) Transforming growth factor-beta3 affects plasminogen activator inhibitor-1 expression in fetal mice and modulates fibroblast-mediated collagen gel contraction. Wound Repair Regen 14:516-25
Huang, Eunice Y; Wu, Huayang; Island, Eddie R et al. (2002) Differential expression of urokinase-type plasminogen activator and plasminogen activator inhibitor-1 in early and late gestational mouse skin and skin wounds. Wound Repair Regen 10:387-96
Island, E; Wu, H; Warburton, D et al. (1999) Developmental differences in the expression and modulation of extracellular matrix proteases and inhibitors in mouse skin fibroblasts. Wound Repair Regen 7:467-76