Mechanical Inputs to Cardiac Fibroblasts and Myocytes Affect Structure, Function, and Signaling Response

Tissues within the body are subject to a variety of physical and chemical cues, many of which play roles in maintaining physiological homeostasis or triggering pathologies. Mechanical stimuli are often less examined by researchers than chemical, though they are important for signal transduction within cells. I explore the role of mechanical inputs in structure, function, and signaling within the predominant cell types of the heart: cardiac fibroblasts and then myocytes. In part one, I examine migratory and adhesion behavior in fibroblasts as directed by substrate stiffness and topography, with emphasis on PIP2 signaling. I find that regulation of PIP2 has significant effects on migratory and adhesion behavior, and the role of neomycin in PIP2 signaling can be exploited by incorporation of the drug into microrod structures for use in a potential wound healing therapeutic. In part two, I study the effect of substrate stiffness on cytoskeletal assembly in cardiomyocytes as regulated through PKCε signaling. This study demonstrates how actin assembly is greatly increased with increased substrate stiffness, which could be a product of increased interactions between PKCε and actin capping protein, CapZ. Combining engineering techniques with biochemical assays, I determine ways in which the mechanical environment elicits differential signaling responses. Culturing cells at non-physiological stiffness triggers abnormal mechanotransduction signaling, which may have major implications for basic understanding and development of biological therapeutics.