Oxylipin Signaling in Congenital Heart Disease

Project summary Congenital heart defects (CHD) constitute the most common type of congenital defect in humans, however the causes for CHD in most cases are unknown. Lipoxygenase-derived oxylipins are a complex and poorly characterized class of highly oxidized, polyunsaturated fatty acid-derived bioactive

lipids with key biological activities. We recently found a link between oxylipin signaling, human cardiovascular development and CHD. This finding is critical not only because of the existing gap in knowledge, but also because oxylipins are strongly dietary-dependent. Our preliminary data suggests lipoxygenases and their oxylipin products dramatically modulate cardiogenic mesoderm formation in

human cardiac differentiation model, and their loss leads to CHD in mice. Our central hypothesis is that endogenous uncharacterized oxylipins are critical regulators of cardiogenic mesoderm specification and heart morphogenesis through cross-talk with the Wnt signaling pathway. Our objective is to provide insight into lipoxygenase and oxylipin signaling pathways during cardiac development and

determine their contribution to mechanisms of CHD. Our Specific aims are: (1) Determine the molecular and cellular mechanisms of oxylipin signaling in human cardiogenic mesoderm specification. (2) Investigate the role of oxylipins in cardiac extracellular matrix organization in a human stem cell- derived cardiac organoid model. (3) Evaluate the contribution of oxylipin signaling to congenital heart

defects in mice. Approach: We will study oxylipin function in human pluripotent stem cell-derived cardiogenic mesoderm and in a 3D cardiac organoid model by combining LC-MS lipidomics, cell and molecular biology and biochemical methods. We will also employ lipoxygenase knockout mice and oxylipin dietary restriction to study oxylipins in cardiac development in vivo in mouse embryos.

Significance: This work addresses a major gap in knowledge by exploring the biological roles of oxylipins in cardiac development, and mechanisms underlying their newly discovered links to CHD. We also offer a novel potential link between diet and congenital heart defects with significant implications

for CHD prevention. Finally, we offer the potential to discover new therapies for treatment by identifying druggable targets and signaling networks. Innovation: We will explore for the first time the key molecular mechanisms linking lipoxygenases, oxylipins and cardiac development signaling networks in

human and mouse tissues. We will also establish a new model of cardiac development that integrates the role of these environmental lipids with developmental molecular networks. Impact: This project will dramatically expand knowledge of oxylipin biology in cardiac development, help develop strategies to

prevent and potentially treat CHD, and develop new tools for the study of oxylipins in human biology.