Sphk2 suppresses ferroptosis in ischemic hearts by promoting HSP90AA1-mediated TFEB nuclear translocation, lysosome biogenesis and lysosome-autophagy pathway-dependent lipid-ROS clearance

Abstract

Background

Lipid peroxidation and iron overload-mediated cardiac ferroptosis play a critical role in myocardial ischemic injury and remodeling. Sphingosine kinase 2 (Sphk2) is implicated in lipid metabolism and cell survival, yet its role in myocardial infarction (MI) remains elusive. Given the critical function of ferroptosis in ischemic injury, we investigated whether Sphk2 protects the heart by regulating this novel cell death pathway.

Methods

Sphk2 expression was assessed in human failing hearts and a murine MI model. Sphk2^−/− mice and AAV9-mediated cardiac-specific Sphk2 overexpression were used to assess cardiac function by echocardiography, remodeling by Masson's trichrome staining and molecular events.

Results

Sphk2 was significantly downregulated in human and murine failing hearts. Sphk2^−/− mice exhibited exacerbated cardiac dysfunction, fibrosis and ferroptosis post-MI. Inhibition of CD36 signaling attenuated lipid uptake and ischemia-induced ferroptosis in Sphk2^−/− mice, whereas pharmacological activation of TFEB restored autophagosome-lysosome function and further suppressed ferroptosis. Mechanistically, Sphk2 deficiency impaired the interaction with and stability of HSP90, leading to suppressed TFEB nuclear translocation, lysosomal biogenesis, and autophagic clearance of lipid peroxides. This exacerbated ferroptosis and ischemic injury via lipid-ROS accumulation and oxidative stress. Crucially, cardiac-specific overexpression of Sphk2 in knockout mice restored HSP90-TFEB signaling, ameliorated ferroptosis, and fully rescued cardiac function and remodeling after MI.

Conclusion

Our study unveils a novel role of Sphk2 in stabilizing HSP90 to activate TFEB-dependent lysosomal function, thereby mitigating lipid peroxidation and ferroptosis following ischemic injury. Our findings establish a direct causal link between Sphk2 deficiency and ischemic heart failure, which highlights the therapeutic potential of Sphk2 restoration in treating ischemic heart disease.