Wnt11 regulates cardiac chamber development and disease during perinatal maturation
Marlin Touma, … , Brian Reemtsen, Yibin Wang
Marlin Touma, … , Brian Reemtsen, Yibin Wang
Published September 7, 2017
Citation Information: JCI Insight. 2017;2(17):e94904. https://doi.org/10.1172/jci.insight.94904.
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Research Article Cardiology Genetics

Wnt11 regulates cardiac chamber development and disease during perinatal maturation

Abstract

Ventricular chamber growth and development during perinatal circulatory transition is critical for functional adaptation of the heart. However, the chamber-specific programs of neonatal heart growth are poorly understood. We used integrated systems genomic and functional biology analyses of the perinatal chamber specific transcriptome and we identified Wnt11 as a prominent regulator of chamber-specific proliferation. Importantly, downregulation of Wnt11 expression was associated with cyanotic congenital heart defect (CHD) phenotypes and correlated with O2 saturation levels in hypoxemic infants with Tetralogy of Fallot (TOF). Perinatal hypoxia treatment in mice suppressed Wnt11 expression and induced myocyte proliferation more robustly in the right ventricle, modulating Rb1 protein activity. Wnt11 inactivation was sufficient to induce myocyte proliferation in perinatal mouse hearts and reduced Rb1 protein and phosphorylation in neonatal cardiomyocytes. Finally, downregulated Wnt11 in hypoxemic TOF infantile hearts was associated with Rb1 suppression and induction of proliferation markers. This study revealed a previously uncharacterized function of Wnt11-mediated signaling as an important player in programming the chamber-specific growth of the neonatal heart. This function influences the chamber-specific development and pathogenesis in response to hypoxia and cyanotic CHDs. Defining the underlying regulatory mechanism may yield chamber-specific therapies for infants born with CHDs.

Authors

Marlin Touma, Xuedong Kang, Fuying Gao, Yan Zhao, Ashley A. Cass, Reshma Biniwale, Xinshu Xiao, Mansuoreh Eghbali, Giovanni Coppola, Brian Reemtsen, Yibin Wang

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Figure 5

Hypoxia regulates neonatal cardiomyocyte proliferation in a chamber-specific manner.

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Hypoxia regulates neonatal cardiomyocyte proliferation in a chamber-spec...
(A) Schematic illustration of experimental design for perinatal systemic hypoxia exposure. Neonatal pups were reared with their dams in either normoxia or hypoxia (10% FIO2) and maintained until the predecided end points (P0, P3, or P7). The dams carrying the experimental group (hypoxia) were acclimatized in the hypoxia chamber by decreasing FIO2 by 2% daily for at least 5 days preceding the experiment starting at E14.5 to reach 10% on E19.5. (B) Wnt11 mRNA expression in left ventricular (LV) and right ventricular (RV) myocardium of WT neonatal mouse at P3 in normoxic and hypoxic conditions (qRT-PCR). n = 5 replicates per condition. (C) Wnt11 protein expression in LV and RV myocardium of WT neonatal mouse at P3 in normoxic and hypoxic conditions (Western blot). Gapdh was used as loading control, n = 3 replicates per condition. See related Supplemental Figure 3. (D) Expression time course of histone H3 protein and p-H3 at Ser10 (S10), P0 through P7, in LV or RV myocardium of WT neonatal mouse hearts in normoxic or hypoxic condition (left panel). n = 5 replicates per condition. (E) Expression of proliferation marker Ki67 for LV or RV myocardium of WT neonatal mouse hearts in normoxic or hypoxic conditions (qRT-PCR). n = 5 replicates per condition. (F) Representative confocal images of anti–phospho-histone H3 (anti–p-H3) immunohistochemistry (IHC) in LVs and RVs of WT neonatal mouse heart at P3 in normoxic and hypoxic conditions. Arrows: representative p-H3–positive cardiomyocytes. Original magnification ×60. Graph: quantitative analysis of p-H3–positive cells (cell number/area [μm2], n = 5 replicates per condition. (G) Expression of cyclin D1 and P21 proteins in LV or RV myocardium of P3 WT neonatal mouse hearts in normoxic or hypoxic condition. β-Actin was used as loading control. n = 5 replicates per condition. (H) Expression time course of Rb1 protein and phosphorylated Rb1 (p-Rb1) at Ser807/811 and Ser780 (S807/811 and S780), P0 through P7, in LV or RV myocardium of WT neonatal mouse hearts in normoxic or hypoxic condition (n = 5 replicates per condition). Error bars represent SEM. *P ≤ 0.05, **P ≤ 0.01 by unpaired, 2-tailed Student’s t test.