MiR-378 Controls Cardiac Hypertrophy by Combined Repression of Mitogen-Activated Protein Kinase Pathway Factors

Abstract

Background— Several microRNAs (miRs) have been shown to regulate gene expression in the heart, and dysregulation of their expression has been linked to cardiac disease. miR-378 is strongly expressed in the mammalian heart but so far has been studied predominantly in cancer, in which it regulates cell survival and tumor growth. Methods and Results— Here, we report tight control of cardiomyocyte hypertrophy through miR-378. In isolated primary cardiomyocytes, miR-378 was found to be both necessary and sufficient to repress cardiomyocyte hypertrophy. Bioinformatic prediction suggested that factors of the mitogen-activated protein kinase (MAPK) pathway are enriched among miR-378 targets. Using mRNA and protein expression analysis along with luciferase assays, we validated 4 key components of the MAPK pathway as targets of miR-378: MAPK1 itself, insulin-like growth factor receptor 1, growth factor receptor-bound protein 2, and kinase suppressor of ras 1. RNA interference with these targets prevented the prohypertrophic effect of antimiR-378, suggesting their functional relation with miR-378. Because miR-378 significantly decreases in cardiac disease, we sought to compensate for its loss through adeno-associated virus–mediated, cardiomyocyte-targeted expression of miR-378 in an in vivo model of cardiac hypertrophy (pressure overload by thoracic aortic constriction). Restoration of miR-378 levels significantly attenuated thoracic aortic constriction–induced cardiac hypertrophy and improved cardiac function. Conclusions— Our data identify miR-378 as a regulator of cardiomyocyte hypertrophy, which exerts its activity by suppressing the MAPK signaling pathway on several distinct levels. Restoration of disease-associated loss of miR-378 through cardiomyocyte-targeted adeno-associated virus–miR-378 may prove to be an effective therapeutic strategy in myocardial disease.

MicroRNA-133 Modulates the β 1 -Adrenergic Receptor Transduction Cascade

“…This result is in line with a growing body of evidence demonstrating that microRNAs play a role in modulating specific receptor pathways in cardiomyocytes. 24,25 For example miR-1, which together with miR-133 is one of the most highly expressed microRNAs in the heart and is transcribed from the same bicistronic unit as miR-133, was found by us and others to regulate the insulin-like growth factor 1/insulin-like growth factor 1 receptor signal transduction pathway, 25,34 a key regulator of cardiac muscle trophism and function. Recent studies have demonstrated a role of βAR signaling in controlling microRNA expression.…”

miR-96 inhibits cardiac hypertrophy by targeting growth factor receptor-bound 2

“…Primary neonatal cardiomyocytes were isolated from 1-day-old Sprague-Dawley rats as described previously (Ganesan et al, 2013). Isolated cardiomyocytes and 293T cells (American Type Culture Collection, Manassas, VA, USA) were cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 1 mM glutamine, 100 U/mL penicillin, and 100 mg/mL streptomycin.…”

“…The cell surface area of α-actin-stained cells or unstained cells was measured as described previously (Ganesan et al, 2013). A total of 100-200 cardiomyocytes in 20-50 fields were examined in each experiment.…”

“…An increasing number of studies have shown that miRNAs are involved in cardiac hypertrophy. For example, miR-378 is a key regulator of cardiac hypertrophy and represses mitogen-activated protein kinase pathway factor (Ganesan et al, 2013;Nagalingam et al, 2013;Nagalingam et al, 2014). miR-133 can suppress cardiac hypertrophy by binding to its targets RhoA, Cdc42, and Nelf-A/WHSC2 (Care et al, 2007).…”

Inter-organ Communication in the Regulation of Lipid Metabolism: Focusing on the Network Between the Liver, Intestine, and Heart

“…In the heart, miR-378 targets growth factor receptor-bound protein 2 (GRB2), insulin-like growth factor 1 receptor (IGF1R), kinase suppressor of ras 1 (KSR1), as well as MAPK1. MiR-378 serves as an endogenous negative regulator of cardiac hypertrophy through the repression of the RAS signaling pathway (9). More information on the miRNA profile associated with cardiac disease has been emerging (10).…”