Dynamic Transcriptional Responses to Injury of Regenerative and Non-regenerative Cardiomyocytes Revealed by Single-Nucleus RNA Sequencing

The adult mammalian heart is incapable of regeneration following injury. In contrast, the neonatal mouse heart can efficiently regenerate during the first week of life. The molecular mechanisms that mediate the regenerative response and its blockade in later life are not understood. Here, by single-nucleus RNA sequencing, we map the dynamic transcriptional landscape of five distinct cardiomyocyte populations in healthy, injured, and regenerating mouse hearts. We identify immature cardiomyocytes that enter the cell cycle following injury and disappear as the heart loses the ability to regenerate. These proliferative neonatal cardiomyocytes display a unique transcriptional program dependent on nuclear transcription factor Y subunit alpha (NFYa) and nuclear factor erythroid 2-like 1 (NFE2L1) transcription factors, which exert proliferative and protective functions, respectively. Cardiac overexpression of these two factors conferred protection against ischemic injury in mature mouse hearts that were otherwise non-regenerative. These findings advance our understanding of the cellular basis of neonatal heart regeneration and reveal a transcriptional landscape for heart repair following injury. [Display omitted] •Neonatal cardiomyocytes (CMs) in mice are heterogeneous•Immature CMs enriched in regenerative hearts enter the cell cycle upon injury•Defined transcriptome changes occur in regenerating CMs in response to injury•NFYa and NFE2L1 exert proliferative and protective functions, respectively, in CMs Using single-nucleus RNA sequencing, Cui et al. identified a unique immature cardiomyocyte population associated with heart regeneration in newborn mice. The NFYa and NFE2L1 factors are activated in these cardiomyocytes after injury and can confer protection against ischemic injury in mature mouse hearts that are otherwise non-regenerative.