Wound healing defects can result from lack of fibroblast migration as observed in non-healing chronic wounds or from excessive myofibroblast formation and function as observed in scarring and pathological contractures. Our long term goal is to regulate fibroblast migration, myofibroblast formation and function, and scarring during abnormal wound healing and to manipulate these cells for therapeutic purposes. The objective is to determine how expression of cytoskeletal proteins in fibroblasts and myofibroblasts are transcriptionally regulated and the consequences altering transcriptional activity has on their formation and function during wound healing. Our central hypothesis is that myocardin-related transcription factor (MRTF)-A and -B are key regulators of fibro- blasts and myofibroblasts during wound healing. The significance is that by understanding MRTF regulation of fibroblasts and myofibroblasts, transcriptional activity of MRTFs can be manipulated, resulting in innovative approaches to preventing and treating chronic wounds, scarring and contractures. To test our hypothesis we will pursue the following specific aims: 1) Identify the transcriptional regulation of contractile protein ex- pression essential for myofibroblast formation and function during wound healing. We hypothesize that MRTF-A is essential for myofibroblast formation, contraction, wound closure, and scar formation. We will eval- uate MRTF-A regulation of myofibroblast formation and scarring in wound healing and scarring using MRTF-A- null mice and in in vitro models of wound healing. 2) Determine how fibroblast migration is transcriptional- ly regulated during wound healing. We hypothesize that MRTF-A and -B redundantly control fibroblast migration essential for granulation tissue formation. MRTF-A and -B regulation of fibroblast migration will be evaluated during wound healing using MRTF-A/B-null mice. The transcriptional activity of MRTF-A and -B in human chronic wound fibroblasts will be evaluated, in vivo and in vitro, and whether increasing transcriptional activity of MRTF-A and -B can restore fibroblast migration. 3) Identify the functional differences between MRTF-A and -B transcriptional activity during wound healing. We hypothesize that MRTF-A and -B have redundant transcriptional activity for fibroblast migration and differing transcriptional activity for myofibroblast formation during wound healing. Using a MRTF inhibitor, we will determine whether differential MRTF tran- scriptional activity can maintain fibroblast migration and inhibit myofibroblast formation and scarring. We will evaluate the different cytoskeletal proteins expressed in response to MRTF-A and -B and the mechanisms for these differing transcriptional activities. This is significant because it is a first step in therapeutically regulating fibroblasts and myofibroblasts during wound healing through regulation of specific transcription factors. This is innovative because it focuses on an entirely different approach to controlling fibroblast migration, myofibroblast formation and scarring by altering transcriptional activity of key transcription factors and provides a novel ap- proach to in the treatment of non-healing wounds, scarring, and pathologic contractures.
Defective wound healing, including chronic wounds, scarring and pathologic contractures, is a major threat to public health and the economy with an estimated excess of $25 billion spent annually on treatments and the burden rapidly growing due to increasing health care costs, an aging population, and a sharp rise in the incidence of diabetes and obesity. The objective of the proposed research is to determine how expression of cytoskeletal proteins in fibroblasts and myofibroblasts are transcriptionally regulated by the myocardin-related transcription factors (MRTFs) and determine the consequences altering transcriptional activity of these transcription factors has on fibroblast migration, myofibroblast formation and function, wound healing and scarring. This project is relevant to NIH's mission because it will examine whether lack of migration of fibroblasts in non-healing chronic wounds is the result of reduced transcriptional activity of MRTFs and whether decreased transcriptional activity of MRTFs can reduce pathologic contractures and scarring. These results are expected to lead to new and substantively different therapies for controlling defective wound healing.
|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|