Abstract 18494: WNT Mediated Regulation Signals IN Chamber-Specific Neonatal Heart Maturation and Disease

Abstract

Background: Chamber-specific and temporally orchestrated perinatal cardiac growth and maturation is critical to functional adaptation of heart to the dramatic changes in hemodynamic load and nutrient environment, and perturbation of this process may have major implications in congenital heart defects (CHDs). However, the responsible molecular regulatory mechanisms are still poorly understood. Objective: To determine the factors that control chamber specificity of neonatal heart growth during perinatal maturation Methods: Total transcriptome was analyzed from deep RNA-seq in male newborn mouse (C57BL) left ventricle (LV) and right ventricle (RV) at postnatal day 0, 3 and 7. Functional validation was performed in Neonatal Rat Ventricular Myocytes (NRVMs) and intact neonatal mice. Results: Chamber specific- regulation of cell cycle genes was correlated with chamber specific- expression of the non-canonical Wnt11. Exogenous expression of Wnt11 induced maturation markers and suppressed cell cycle genes in myocytes. In contrast, targeted Wnt11 inhibition induced myocyte proliferation associated with upregulated cell cycle genes both in cultured NRVMs and in the intact heart. Notably, Wnt inhibition also significantly enhanced β-catenin phosphorylation without impacting JNK, PKCα, or p38- activities. Remarkably, both Wnt mediated signals and cell cycle markers were altered in heart samples from infants cyanotic CHDs. Furthermore, hypoxia exposure suppressed Wnt11 and induced cell cycle genes in cultured cardiomyocytes. Conclusions: Differential expression of Wnt11 and downstream cell cycle genes are novel molecular basis for chamber specific maturation. Wnt11 mediated-signaling has potential impact on cyanotic CHDs. Differential role of Wnt signaling in chamber specific post-natal heart maturation can lead to potential chamber-specific diagnoses and therapies for congenital heart diseases.