Cardiomyocyte S1pr1 regulates cardiac regeneration via AKT/mTOR signaling pathway

Mammalian hearts had the capability to regenerate cardiomyocyte and completely recover after heart injury within a limited time window after birth. It has been shown that sphingosine 1-phospahte receptor 1 (S1pr1) was highly expressed in cardiomyocytes and played an important role in heart development and pathological cardiac remodeling. Herein, we aim to investigate the role of CM-S1pr1 for cardiac regeneration and tissue repair after heart injury. We generated cardiomyocyte (CM)-specific S1pr1 knock-out mice and showed that CM-specific S1pr1 loss-of-function significantly severely reduced cardiomyocyte proliferation and heart regeneration in neonatal mice after both apex resection and myocardial infarction, whereas S1pr1 gain-of-function by AAV9-mediated CM-specific overexpression of S1pr1 significantly boosted cardiac regeneration and improved cardiac functions after heart injuries. We next identified that S1pr1 activated AKT/mTOR/CyclinD1 and Bcl-2 signaling pathways, and thus promoted cardiomyocyte proliferation and inhibited CM apoptosis, respectively.Of note, we applied CM-targeted gene therapy by AAV9-cTNT to specifically overexpress S1pr1 in cardiomyocytes and achieved an efficient S1pr1 overexpression in CMs in vivo. This CM-targeted strategy to overexpress S1pr1 significantly enhanced cardiac regeneration and improved cardiac functions after myocardial infarction in an adult mouse model, suggesting a potential strategy to boost adult cardiac regeneration in vivo. To gain insight into the molecular processes affected by CM-S1pr1 deficiency we performed gene expression analysis of heart tissues from S1pr1CMKO and WT neonates by RNA sequencing (n=2/groups).