The promise of enhancer-associated long noncoding RNAs in cardiac regeneration

Heart failure is a worldwide epidemic and represents a major cause of morbidity and mortality. Current clinical therapies for heart disease prolong survival by protecting the viable muscle, but they are unable to replenish lost cardiomyocytes to restore function. Over the last decade, the notion of promoting cardiac regeneration has engendered considerable research interest. New strategies envisage the transfer of stem cells into the damaged myocardium, the mobilization of cardiac precursor cells, the promotion of cardiomyocyte proliferation in situ and direct reprogramming of non-cardiac cells into electromechanically coupled cardiomyocytes. The molecular and cellular mechanisms underpinning these different regenerative avenues are under the control of integrated transcriptional programs, which are ultimately dependent on epigenomic reprogramming and reorganization of the genome nuclear architecture. Today, it is becoming evident that regulatory noncoding RNAs play fundamental roles in all these aspects of gene regulatory network activity. In particular, thousands of long noncoding RNAs are dynamically expressed across the entire genome during lineage-specific commitment, specialization, and differentiation, as well as during the response to environmental cues. Here, we review this emerging landscape, focusing particularly on a unique class of lncRNA emerging from enhancer sequences, the enhancer-associated lncRNAs, in the context of cardiac regeneration. We propose that characterizing and manipulating these enhancer-assodated transcripts could provide a novel approach to awaken the dormant regenerative potential of the adult mammalian heart. Ultimately, this could lead to targeted noncoding RNA-based enhancer therapies to improve effectiveness of current regenerative strategies and provide new avenues for repair. (C) 2015 The Authors. Published by Elsevier Inc.