Cardiovascular development defects produced by combined loss of RGS6 and oxidizable CaMKII due to defective Notch signaling

Abstract

Congenital heart defects (CHDs) are the most common birth defects with nearly 40,000 infants born annually with a CHD in the U.S. alone. There is a critical lack of understanding of the etiology of CHDs and therefore, effective therapeutic strategies for this disease. Emerging evidence has implicated defective Notch signaling as the major cause of embryonic death of mice due to cardiovascular defects. RGS6 is abundantly expressed in the heart and mediates doxorubicin (Dox)‐ and alcohol‐induced myocardial cell apoptosis and cardiomyopathies by functioning as an upstream activator of NADPH oxidase (Nox) and consequent reactive oxygen species (ROS) generation. Oxidative activation of the Ca2+/calmodulin‐dependent protein kinase II δ (CaMKIIδ) on two key methionines in response to ROS generation in heart promotes cardiac disease including cardiomyopathy and cell death. While interrogating the relationship between RGS6 and CaMKII oxidation in heart we discovered a severe defect in embryonic cardiovascular development due to combined loss of RGS6 and ox‐CaMKII. To determine the function of RGS6 and ox‐CaMKII in embryonic cardiovascular development and the underlying mechanisms responsible for cardiovascular defects due to their combined loss, we developed double mutant (RGS6−/−/CaMKIIVV) mice by intercrossing of knock‐in mice expressing an oxidation resistant form of CaMKIIδ (CaMKIIVV) and RGS6−/− mice. Here, we show that RGS6−/−/CaMKIIVV mice undergo midgestational embryonic lethality associated with cardiac, hematopoietic, and vascular remodeling defects in placentas, yolk sacs, and embryos. Combined loss of RGS6 and ox‐CaMKII promoted endothelial cell apoptosis in hearts and decreased the expression of arterial markers and Notch signaling genes including Efnb2, Gja4, Gja5, Notch1, Jag1, Hey1, Hey2 and Hey1L in both yolk sacs and embryos. In conclusion, RGS6 and ox‐CaMKII are required together for cardiovascular development and function in parallel pathways as critical upstream modulators of Notch signaling.Support or Funding InformationNIH CA161882, AHA 14GRNT20460208 [RAF] and AHA 11SDG7580008 [JY]