Sphingolipid metabolism controls mammalian heart regeneration.

Utilization of lipids as energy substrates after birth causes cardiomyocyte (CM) cell-cycle arrest and loss of regenerative capacity in mammalian hearts. Beyond energy provision, proper management of lipid composition is crucial for cellular and organismal health, but its role in heart regeneration remains unclear. Here, we demonstrate widespread sphingolipid metabolism remodeling in neonatal hearts after injury and find that SphK1 and SphK2, isoenzymes producing the same sphingolipid metabolite sphingosine-1-phosphate (S1P), differently regulate cardiac regeneration. SphK2 is downregulated during heart development and determines CM proliferation via nuclear S1P-dependent modulation of histone acetylation. Reactivation of SphK2 induces adult CM cell-cycle re-entry and cytokinesis, thereby enhancing regeneration. Conversely, SphK1 is upregulated during development and promotes fibrosis through an S1P autocrine mechanism in cardiac fibroblasts. By fine-tuning the activity of each SphK isoform, we develop a therapy that simultaneously promotes myocardial repair and restricts fibrotic scarring to regenerate the infarcted adult hearts. [Display omitted] • Injury induces robust sphingolipid metabolism dynamics in the neonatal mouse hearts • SphK2 promotes CM proliferation via nuclear S1P-dependent histone acetylation • SphK1 depletion limits autocrine activation of CFs by S1P and promotes regeneration • Introduction of the neonatal SphK1/SphK2 pattern induces adult heart regeneration Ji et al. identified that SphK1 and SphK2, isoenzymes producing the same sphingolipid metabolite S1P, differently regulate mammalian heart regeneration. SphK2 promotes cardiomyocyte proliferation and regeneration via nuclear S1P-dependent modulation of histone acetylation, whereas SphK1 hampers regeneration through an S1P autocrine mechanism in cardiac fibroblasts. [ABSTRACT FROM AUTHOR]