Tissue contraction is an integral part of wound closure;however, excessive or abnormal contraction of tissues can lead to pathological contractures, tissue deformation and loss of tissue function, all major health problems in the United States. The long-term goal of this project is to understand the cellular basis underlying wound contraction and tissue contracture by studying the formation and function of the myofibroblast. Myofibroblasts are specialized fibroblasts that express smooth muscle alpha-actin (SMAA) and assemble contractile structural elements as part of their ability to generate the contractile force responsible for tissue contraction. The mechanical properties of the extracellular matrix are critical in regulating SMAA expression, as well as other SM-specific cytoskeletal proteins, and myofibroblast formation and function. These results have led to a series of novel hypothesis regarding mechano-regulation of myofibroblast formation and function: (i) mechano-regulation of the SM-specific cytoskeletal expression in myofibroblasts is mediated by changes in actin dynamics;(ii) myocardin-related transcription factor A (MRTF-A) couples mechano-regulated changes in actin dynamics with gene expression by translocating from cytoplasmic actin to the nucleus;(iii) MRTF-A activates a subset of SM-specific cytoskeletal proteins, in addition to SMAA, in myofibroblasts;(iv) MRTF-A activation of this subset of SM-specific cytoskeletal proteins is responsible for the formation and function of myofibroblasts. We will test these hypotheses by use of tissue culture and animal wound models in which response to different mechanical environments can be examined. In addition, we will knock down expression of MRTF-A and SMAA using siRNA to determine their role in myofibroblast formation and function. Relevance to Public Health: In order to control wound healing and the devastating effects of pathological contractures it is essential to regulate the formation and function of the myofibroblast. This proposal will test whether myofibroblast formation and function can be regulated by targeting specific signaling pathways and transcriptional regulatory events and the effect this has on wound healing and tissue contracture in animal models. This study will provide the basis for translating basic science findings on the myofibroblast formation and function into the development of novel therapeutic approaches to control wound healing and pathologic contractures.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM060651-07
Application #
7541366
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Ikeda, Richard A
Project Start
2000-02-01
Project End
2010-12-31
Budget Start
2009-01-01
Budget End
2009-12-31
Support Year
7
Fiscal Year
2009
Total Cost
$317,774
Indirect Cost
Name
University of Oklahoma Health Sciences Center
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
878648294
City
Oklahoma City
State
OK
Country
United States
Zip Code
73117
Tomasek, James J; Haaksma, Carol J; Schwartz, Robert J et al. (2013) Whole animal knockout of smooth muscle alpha-actin does not alter excisional wound healing or the fibroblast-to-myofibroblast transition. Wound Repair Regen 21:166-76
Howard, Eric W; Crider, Beverly J; Updike, Dawn L et al. (2012) MMP-2 expression by fibroblasts is suppressed by the myofibroblast phenotype. Exp Cell Res 318:1542-53
Haaksma, Carol J; Schwartz, Robert J; Tomasek, James J (2011) Myoepithelial cell contraction and milk ejection are impaired in mammary glands of mice lacking smooth muscle alpha-actin. Biol Reprod 85:13-21
Crider, Beverly J; Risinger Jr, George M; Haaksma, Carol J et al. (2011) Myocardin-related transcription factors A and B are key regulators of TGF-?1-induced fibroblast to myofibroblast differentiation. J Invest Dermatol 131:2378-85
Mirastschijski, Ursula; Schnabel, Reinhild; Claes, Juliane et al. (2010) Matrix metalloproteinase inhibition delays wound healing and blocks the latent transforming growth factor-beta1-promoted myofibroblast formation and function. Wound Repair Regen 18:223-34
Risinger Jr, George M; Updike, Dawn L; Bullen, Elizabeth C et al. (2010) TGF-beta suppresses the upregulation of MMP-2 by vascular smooth muscle cells in response to PDGF-BB. Am J Physiol Cell Physiol 298:C191-201
Gallucci, Randle M; Lee, Eric G; Tomasek, James J (2006) IL-6 modulates alpha-smooth muscle actin expression in dermal fibroblasts from IL-6-deficient mice. J Invest Dermatol 126:561-8
Tomasek, James J; Vaughan, Melville B; Kropp, Bradley P et al. (2006) Contraction of myofibroblasts in granulation tissue is dependent on Rho/Rho kinase/myosin light chain phosphatase activity. Wound Repair Regen 14:313-20
Mirastschijski, Ursula; Haaksma, Carol J; Tomasek, James J et al. (2004) Matrix metalloproteinase inhibitor GM 6001 attenuates keratinocyte migration, contraction and myofibroblast formation in skin wounds. Exp Cell Res 299:465-75