Secreted long non-coding RNAsGadlor1andGadlor2aggravate cardiac remodelling during pressure overload by affecting multiple cardiac cell types

Abstract

AbstractAimsPathological overload triggers maladaptive myocardial remodelling that leads to heart failure. Recent studies have shown that long non-coding RNAs (lncRNAs) contribute to the development of cardiac disease. This study investigates two recently discovered and secreted lncRNAs,Gadlor1andGadlor2(Gadlor 1/2).Methods and ResultsIn the heart,Gadlor 1/2are mainly expressed in endothelial cells and to a lesser extent in fibroblasts and cardiomyocytes.Gadlor1/2are upregulated in failing mouse hearts as well as in the myocardium and serum of heart failure patients. Interestingly,Gadlor1/2are secreted from endothelial cells (EC) within extracellular vesicles (EV) and are taken up by cardiomyocytes.Gadlor1/2 knock-out (Gadlor-KO) and overexpression during experimental cardiac pressure overload by transverse aortic constriction (TAC) was analysed.Gadlor-KO mice exhibited reduced cardiomyocyte hypertrophy, enhanced angiogenesis, diminished myocardial fibrosis, and improved cardiac function, but paradoxically suffered from sudden death during prolonged overload.Gadlor1/2overexpression, in turn, aggravated hypertrophy, fibrosis and cardiac dysfunction during TAC. Mechanistically,Gadlor1/2inhibited angiogenic gene expression in endothelial cells, while promoting the expression of pro-fibrotic genes in cardiac fibroblasts. We employed RNA antisense purification coupled with mass spectrometry (RAP-MS) and identified the calcium/calmodulin-dependent protein kinase type II (CaMKII) as interaction partner ofGadlor1/2in cardiomyocytes. By activating CaMKII,Gadlor1/2promoted hypertrophic gene-expression and excitation-contraction coupling in these cells. Accordingly,Gadlorablation entailed reduced hypertrophy, but also increased diastolic calcium levels in the cytosol and arrhythmic beating in cardiomyocytes.ConclusionGadlor1andGadlor2are novel lncRNAs that are mainly enriched in EC-derived EVs and are upregulated in mouse and human hearts during pathological overload.Gadlor1/2affect multiple cardiac cell types and inhibit angiogenesis, induce myocardial fibrosis and hypertrophy as well as alterations in calcium homeostasis in cardiomyocytes. We suggest that inhibition ofGadloreffects in cardiac non-myocytes could be a therapeutic strategy in heart failure.Translational PerspectiveHere, we characterized two secreted lncRNAsGadlor1/2, which are conserved in humans. We observed increasedGadlor1/2levels in human failing myocardium and a negative correlation betweenGADLOR2serum levels and left ventricular ejection fraction in heart failure patients.Gadlor1/2ablation in mice reduces cardiac hypertrophy and fibrosis and increases angiogenesis, but slows calcium re-uptake into the sarcoplasmic reticulum (SR) and might thereby trigger arrhythmia and sudden death when cardiac overload persists in the long term. Inhibition ofGadlor1/2effects in endothelial cells and fibroblasts, on the other hand, could be beneficial by increasing angiogenesis and reducing fibrosis in the heart.