Long Non-coding RNA ECRAR Triggers Post-natal Myocardial Regeneration by Activating ERK1/2 Signaling

Abstract

Reactivating post-natal myocardial regeneration potential may be a feasible strategy to regenerate the injured adult heart. Long non-coding RNAs (lncRNAs) have been implicated in regulating cellular differentiation, but whether they can elicit a regenerative response in the post-natal heart remains unknown. In this study, by characterizing the lncRNA transcriptome in human hearts during the fetal-to-adult transition, we found that 3,092 lncRNAs were differentially expressed, and we further identified a novel upregulated fetal lncRNA that we called endogenous cardiac regeneration-associated regulator (ECRAR), which promoted DNA synthesis, mitosis, and cytokinesis in post-natal day 7 and adult rat cardiomyocytes (CMs). Overexpression of ECRAR markedly stimulated myocardial regeneration and induced recovery of cardiac function after myocardial infarction (MI). Knockdown of ECRAR inhibited post-natal day 1 CM proliferation and prevented post-MI recovery. ECRAR was transcriptionally upregulated by E2F transcription factor 1 (E2F1). In addition, ECRAR directly bound to and promoted the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), resulting in downstream targets of cyclin D1 and cyclin E1 activation, which, in turn, activated E2F1. The E2F1-ECRAR-ERK1/2 signaling formed a positive feedback loop to drive cell cycle progression, and, therefore, it promoted CM proliferation. These findings indicated that our newly discovered ECRAR may be a valuable therapeutic target for heart failure.

circRNA Hipk3 Induces Cardiac Regeneration after Myocardial Infarction in Mice by Binding to Notch1 and miR-133a

“…Adult mouse CMs were isolated from 10-week-old adult mice using a modified protocol as described. 35 Briefly, when the adult mouse was anesthetized, the heart was rapidly excised and mounted on a Langendorff apparatus. Then, the heart was perfused with calcium-free perfusion buffer (113 mM NaCl, 4.7 mM KCl, 0.6 mM KH 2 PO 4 , 0.6 mM Na 2 HPO 4 , 1.2 mM MgSO 4 , 10 mM Na-HEPES, 12 mM NaHCO 3 , 10 mM KHCO 3 , 0.032 mM phenol red, 30 mM taurine, 10 mM 2,3-butanedione monoxime [BDM], and 5.5 mM glucose) for 5 min, followed by the addition of 50 mL digestion buffer composed of 15,000 U of type II collagenase (Roche) and 50 μM CaCl 2 for 10 min.…”

“…The animal studies were conducted as previously described. 35 , 40 Briefly, adult mice were intramyocardially injected at 3–5 sites with AAV9 vectors expressing circHipk3 or empty vectors (AAV9-circHipk3 or AAV9-vector) at a dose of 1,011 viral genome particles per mouse (approximately 30 μL) using an insulin syringe with a 30-gauge needle. For the infarcted mice, AAV9 was injected into myocardial tissue close to the infarct zone immediately after the left anterior descending coronary artery ligation.…”

Noncoding RNAs in cardiovascular diseases

“…Similar to the above-mentioned lncRNAs several others have been shown to mediate cardiomyocyte proliferation mainly by perturbing miRNAs and direct binding to proteins [12,[24][25][26] *.…”

Expedition to the missing link: Long noncoding RNAs in cardiovascular diseases

“…In addition, further analysis revealed that E2F1 transcriptionally upregulates ECRAR. Therefore, E2F1-ECRAR-ERK1/2 form a positive feedback loop to drive CM proliferation [124].…”