LncRNA Snhg1-driven self-reinforcing regulatory network promotes cardiomyocyte cytokinesis and improves cardiac function

Most of current cardiac regenerative approaches result in very limited cell division. Positive feedback loops are vital for cell division, but their role in CM regeneration remains unclear. We aimed to demonstrate that lncRNA Snhg1 formed a positive feedback loop with c-Myc to induce stable CM cytokinesis. We found that Snhg1 expression was increased in human and mouse fetal and myocardial infarction (MI) hearts, particularly in CMs. Snhg1 overexpression elicited stable CM proliferation and improved post-MI cardiac function. Antagonism of Snhg1 in neonatal mice inhibited CM proliferation and impaired cardiac repair after MI. Proliferative effect was confirmed using cardiac-specific transgenic mice. RNA pull-down assays showed that Snhg1 directly bound to PTEN and activated PI3K-Akt pathway, resulting in c-Myc activation. Chromatin immunoprecipitation experiments showed that Snhg1 expression was upregulated by c-Myc binding to the Snhg1 promoter region, indicating a positive feedback loop between c-Myc and Snhg1. In conclusion, c-Myc/Snhg1/PI3k-Akt positive feedback loop drove sustained activation of cell cycle re-entry and induced stable CM cytokinesis, and thus may be an attractive strategy for promoting heart regenerative response.\n\nClinical Perspectives Most of the current cardiac regenerative approaches result in very limited cell division and little new cardiomyocyte (CM) mass. Positive feedback loops are vital for cell division, but their role in CM regeneration remain unclear. Here, we identified the long noncoding RNA Snhg1 as a driver to induce stable CM division and improve cardiac function after myocardial infarction (MI) by forming a positive feedback loop to sustain PI3K-Akt signaling activation. This finding might provide a novel therapeutic of Snhg1 as a promising regenerative approach to improve the prognosis of patients with heart failure.