The Role of SRC in Strain- and Ligand- Dependent Phenotypic Modulation of Mouse Embryonic Fibroblasts

Connective tissue fibrosis represents a significant portion of mortality and morbidity in our society. These diseases include many illnesses such as heart valve disease, atherosclerosis, macular degeneration, and cirrhosis, meaning that millions of lives are affected by these conditions each year. Fibrotic tissues form when quiescent fibroblasts activate becoming myofibroblasts, the phenotype of active tissue construction and fibrosis. During this process, the cells produce smooth muscle α-actin (αSMA), a contractile element considered to be the hallmark of cellular activation [1]. Following the production of αSMA, there is an increase in the synthesis of extracellular matrix (ECM) proteins, most notably type I collagen; this increase in ECM proteins causes the stiffening of the tissue characteristic of fibrotic disease. In non-disease states (such as wound healing or tissue development), the myofibroblasts will either deactivate, becoming fibroblasts again, or apoptose before tissue fibrosis occurs. However, when myofibroblasts persist, increased ECM protein deposition causes increased tissue stiffness and activates neighboring cells, causing the fibrosis to propagate. Currently there are no therapies to prevent or reverse fibrosis. Therefore a more thorough understanding of the dynamic mechanical environment and signaling pathways involved in the activation of fibroblasts is required to develop potential treatments.