Engineering troponin C with altered Ca2+ binding properties to study mechanisms of enhanced contraction of cardiac muscle from healthy and infarcted hearts
MetadataShow full item record
Heart failure is the leading cause of morbidity and mortality in developed nations. It is responsible for 1 in every 3 deaths while costing over $500 billion annually in the United States alone. Unfortunately, most current treatments for heart failure are palliative approaches that fail to restore any functional capacity to the heart. This significant lack of effective clinical treatments underscores the need to develop new therapies for heart failure focused on recovery of cardiac function. Motivated by this need, the long-term goal of this dissertation was to improve the mechanistic understanding of how modulating myofilament Ca2+ binding properties affects cardiac muscle contraction and apply it to the development of a novel cardiac muscle-targeted gene therapy to improve heart function. From both mechanistic and therapeutic perspectives, it was important to understand how manipulating thin and thick filament properties impacted cardiomyocyte and whole heart function. I demonstrated that altering myofilament Ca2+ binding properties via troponin modulations with L48Q cTnC or phosphorylation states of cTnI sets cardiac thin filament activation levels and the SL dependence of Ca2+ sensitivity of force. I also improved healthy and diseased intact cardiomyocyte contractility without perturbing relaxation or Ca2+ transient properties by increasing myofilament Ca2+ binding properties (via L48Q cTnC) or crossbridge cycle kinetics (via dATP). Based on these promising results in intact cardiomyocytes, I engineered a novel cardiac muscle-specific AAV6 gene delivery system to investigate the effects of in vivo expression of L48Q cTnC on whole heart function. This dissertation translated the insights gained from basic science research to the development a potential strategy to treat heart failure. In doing so, it established the foundation for a number of on-going collaborations in the lab and additional studies, including evaluation of the AAV6 L48Q cTnC system as a therapeutic strategy to enhance whole heart function.
- Bioengineering