Hearty miR-363 controls HAND1 in cardiac cell specification

Post-Transcriptional Regulation of Molecular Determinants during Cardiogenesis

Cardiovascular development is initiated soon after gastrulation as bilateral precardiac mesoderm is progressively symmetrically determined at both sides of the developing embryo. The precardiac mesoderm subsequently fused at the embryonic midline constituting an embryonic linear heart tube. As development progress, the embryonic heart displays the first sign of left-right asymmetric morphology by the invariably rightward looping of the initial heart tube and prospective embryonic ventricular and atrial chambers emerged. As cardiac development progresses, the atrial and ventricular chambers enlarged and distinct left and right compartments emerge as consequence of the formation of the interatrial and interventricular septa, respectively. The last steps of cardiac morphogenesis are represented by the completion of atrial and ventricular septation, resulting in the configuration of a double circuitry with distinct systemic and pulmonary chambers, each of them with distinct inlets and outlets connections. Over the last decade, our understanding of the contribution of multiple growth factor signaling cascades such as Tgf-beta, Bmp and Wnt signaling as well as of transcriptional regulators to cardiac morphogenesis have greatly enlarged. Recently, a novel layer of complexity has emerged with the discovery of non-coding RNAs, particularly microRNAs and lncRNAs. Herein, we provide a state-of-the-art review of the contribution of non-coding RNAs during cardiac development. microRNAs and lncRNAs have been reported to functional modulate all stages of cardiac morphogenesis, spanning from lateral plate mesoderm formation to outflow tract septation, by modulating major growth factor signaling pathways as well as those transcriptional regulators involved in cardiac development.

microRNA-363-3p reduces endothelial cell inflammatory responses in coronary heart disease via inactivation of the NOX4-dependent p38 MAPK axis

Coronary heart disease (CHD) is one of the leading causes of heart-associated deaths worldwide. This study aimed to investigate the mechanism by which microRNA-363-3p (miR-363-3p) regulates endothelial injury induced by inflammatory responses in CHD. The expression patterns of miR-363-3p, NADPH oxidase 4 (NOX4), and p38 MAPK/p-p38 MAPK were examined in an established atherosclerosis (AS) model in C57BL/6 mice and in isolated coronary arterial endothelial cells (CAECs) after gain- or loss-of-function experiments. We also measured the levels of inflammatory factors (IL-6, ICAM-1, IL-10 and IL-1β), hydrogen peroxide (H₂O₂), and catalase (CAT) activity, followed by detection of cell viability and apoptosis. In AS, miR-363-3p was downregulated and NOX4 was upregulated, while miR-363-3p was identified as targeting NOX4 and negatively regulating its expression. The AS progression was reduced in NOX4 knockout mice. Furthermore, miR-363-3p resulted in a decreased inflammatory response, oxidative stress, and cell apoptosis in CAECs while augmenting their viability via blockade of the p38 MAPK signaling pathway. Overall, miR-363-3p hampers the NOX4-dependent p38 MAPK axis to attenuate apoptosis, oxidative stress injury, and the inflammatory reaction in CAECs, thus protecting CAECs against CHD. This finding suggests the miR-363-3p-dependent NOX4 p38 MAPK axis as a promising therapeutic target for CHD.

miR-873 suppresses H9C2 cardiomyocyte proliferation by targeting GLI1

MicroRNAs (miRNAs) are a class of endogenous, non-coding small RNAs that regulate the expression of target genes. Previous studies have suggested that miRNAs are key regulators in cardiovascular systems. This study investigated the role of miR-873 in H9C2 cardiomyocytes by targeting glioma-associated oncogene 1 (GLI1). miR-873 was significantly up-regulated in serum samples from congenital heart disease (CHD) patients compared with those from normal individuals. Furthermore, miR-873 over-expression suppressed H9C2 proliferation and induced cell cycle arrest. Bioinformatic algorithms revealed a predicted target site for miR-873 in the 3'-untranslated region (3'UTR) of GLI1, which was verified using a dual-luciferase reporter assay. qPCR and western blot analysis also showed that miR-873 negatively regulated GLI1 mRNA and protein expression in H9C2 cells. Conversely, GLI1 over-expression partially reversed the growth-inhibitory effect of miR-873. To summarize, our data suggest that miR-873 is a novel miRNA that regulates H9C2 cell proliferation via targeting GLI1, and miR-873 may serve as a new potential biomarker diagnosis in CHD in the future.

Inhibition of miR-363 protects cardiomyocytes against hypoxia-induced apoptosis through regulation of Notch signaling

Cardiomyocyte apoptosis contributes to the pathological process of ischemic heart diseases, such as myocardial infarction. Emerging evidence suggests that microRNAs (miRNAs) play critical roles in the pathological process of myocardial infarction by regulating cardiomyocyte apoptosis. Previous studies have reported that miR-363 is an apoptosis-related miRNA. However, whether miR-363 is involved in regulating cardiomyocyte apoptosis remains unclear. This study aimed to investigate the potential role of miR-363 in the regulation of hypoxia-induced cardiomyocyte apoptosis. We found that miR-363 expression was significantly increased in hypoxic cardiomyocytes and that inhibition of miR-363 effectively protected cardiomyocytes against hypoxia-induced apoptosis. Bioinformatics analysis predicted that Notch1 is a potential target gene of miR-363. This finding was validated by dual-luciferase reporter assay, real-time quantitative polymerase chain reaction, and Western blot analysis. miR-363 inhibition significantly promoted the activation of Notch signaling in hypoxic cardiomyocytes. However, knockdown of Notch1 markedly reversed the protective effects induced by miR-363 inhibition. Furthermore, blocking the Notch signaling also significantly abrogated the protective effects of miR-363 inhibition. Overall, these findings suggest that inhibition of miR-363 protects cardiomyocytes against hypoxia-induced apoptosis through promotion of Notch1 expression and activation of Notch signaling. Our study provides a novel understanding of the molecular basis of hypoxia-induced cardiomyocyte apoptosis and suggests a potential therapeutic target for myocardial infarction.