Ablation of lncRNA attenuates pathological hypertrophy and heart failure.

The conserved long non-coding RNA (lncRNA) myocardial infarction associate transcript () was identified for its multiple single-nucleotide polymorphisms that are strongly associated with susceptibility to MI, but its role in cardiovascular biology remains elusive. Here we investigated whether regulates cardiac response to pathological hypertrophic stimuli. Both an angiotensin II (Ang II) infusion model and a transverse aortic constriction (TAC) model were used in adult WT and -null knockout (-KO) mice to induce pathological cardiac hypertrophy. Heart structure and function were evaluated by echocardiography and histological assessments. Gene expression in the heart was evaluated by RNA sequencing (RNA-seq), quantitative real-time RT-PCR (qRT-PCR), and Western blotting. Primary WT and -KO mouse cardiomyocytes were isolated and used in Ca transient and contractility measurements. Continuous Ang II infusion for 4 weeks induced concentric hypertrophy in WT mice, but to a lesser extent in -KO mice. Surgical TAC for 6 weeks resulted in decreased systolic function and heart failure in WT mice but not in -KO mice. In both models, -KO mice displayed reduced heart-weight to tibia-length ratio, cardiomyocyte cross-sectional area, cardiomyocyte apoptosis, and cardiac interstitial fibrosis and a better-preserved capillary density, as compared to WT mice. In addition, Ang II treatment led to significantly reduced mRNA and protein expression of the Ca cycling genes Sarcoplasmic/endoplasmic reticulum Ca ATPase 2a (SERCA2a) and ryanodine receptor 2 (RyR2) and a dramatic increase in global RNA splicing events in the left ventricle (LV) of WT mice, and these changes were largely blunted in -KO mice. Consistently, cardiomyocytes isolated from -KO mice demonstrated more efficient Ca cycling and greater contractility. Ablation of attenuates pathological hypertrophy and heart failure, in part, by enhancing cardiomyocyte contractility.