Optogenetics has primarily employed light gated ion channels (derived from lower organisms) to trigger or inhibit the neuronal action potential. Analogous studies in the cardiovascular field have used these photoresponsive foreign proteins to regulate contractility and pacing. However, light gated ion channels are unable to interrogate the intracellular mechanisms that control behavior and homeostasis. As a consequence, we have developed a protein engineering strategy for creating light responsive analogs of endogenous proteins. The proposed research program is focused on the design, construction, and validation of optogenetic signaling for proteins that contribute to myocardial homeostasis, and the application of this technology to unravel the mechanisms that drive cardiac hypertrophy and fibrosis. Aim 1: Optogenetic Engineering to Access the Biochemical Pathways of Hypertrophy and Fibrosis. We will employ a novel optogenetic engineering strategy to create light responsive signaling cascades localized at specific intracellular sites, with a focus on cAMP-mediated signaling pathways. Aim 2: Light Guided Mapping of the Signaling Domains that Mediate Hypertrophy. The optogenetic constructs outlined in Aim 1 will be used to explore the impact of signaling events at distinct intracellular locations on cardiomyocyte behavior, with an emphasis on hypertrophic relevant responses. Aim 3: Light Guided Mapping of the Intercellular Communication that Mediates Fibrosis. Optogenetic analogs of endogenous proteins will be used to assess intercellular crosstalk between two distinct cardiac cell types. Light- triggered activation of engineered signaling pathways offers the opportunity to tease apart a collaborative signaling network that has been observed between these distinct cell populations.

Project Narrative More than 40% of the US population is projected to suffer from some form of cardiovascular disease within the next decade. This creates a pressing need for novel scientific approaches that can identify therapeutic targets in the intricate cascades that facilitate diseased states of the heart. The studies outlined in this grant application seek to engineer, validate and use optogenetic proteins to better define the specific signaling players of cardiac hypertrophy.