Fibroblast Differentiation in Wound Healing

描述（由申请人提供）：组织收缩是伤口闭合的一个组成部分；然而，组织过度或异常收缩可导致病理性收缩、组织变形和组织功能丧失，这些都是美国的主要健康问题。该项目的长期目标是通过研究肌成纤维细胞的形成和功能来了解伤口收缩和组织挛缩的细胞基础。肌成纤维细胞是特化的成纤维细胞，表达平滑肌α -肌动蛋白（SMAA），并组装收缩结构元件，作为其产生组织收缩力的能力的一部分。细胞外基质的机械特性在调节SMAA表达以及其他sm特异性细胞骨架蛋白和肌成纤维细胞形成和功能方面至关重要。这些结果导致了一系列关于肌成纤维细胞形成和功能的机械调节的新假设：(1)肌成纤维细胞中sm特异性细胞骨架表达的机械调节是由肌动蛋白动力学的变化介导的；（ii）心肌素相关转录因子A （MRTF-A）通过从细胞质肌动蛋白转移到细胞核，将肌动蛋白动力学的机械调节变化与基因表达结合起来；（iii）除了SMAA外，MRTF-A还激活肌成纤维细胞中sm特异性细胞骨架蛋白的一个子集；（iv） MRTF-A对sm特异性细胞骨架蛋白亚群的激活与肌成纤维细胞的形成和功能有关。我们将通过使用组织培养和动物伤口模型来测试这些假设，其中可以检查对不同机械环境的反应。此外，我们将使用siRNA敲低MRTF-A和SMAA的表达，以确定它们在肌成纤维细胞形成和功能中的作用。与公共卫生相关：为了控制伤口愈合和病理性挛缩的破坏性影响，必须调节肌成纤维细胞的形成和功能。本研究将在动物模型中测试肌成纤维细胞的形成和功能是否可以通过靶向特定的信号通路和转录调节事件来调节，以及这对伤口愈合和组织挛缩的影响。该研究将为将肌成纤维细胞形成和功能的基础科学发现转化为控制伤口愈合和病理性挛缩的新治疗方法的发展提供基础。

DESCRIPTION (provided by applicant): 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.