Schisandrin B attenuates ischemic acute kidney injury in a CTR1-dependent manner by inhibiting cuproptosis

Acute kidney injury (AKI) remains a global health challenge with high mortality rates and no targeted pharmacotherapy. Although regulated cell death (RCD) drives renal tubular epithelial cell (RTEC) injury, the involvement of cuproptosis, a copper-triggered RCD characterized by lipoylated protein aggregation and iron-sulfur cluster loss, remains unexplored in acute kidney injury (AKI).

Integrated single-cell transcriptomics (GSE180420), a human renal biopsy cohort (n = 22), ischemia-reperfusion (I/R) mouse models, and hypoxia-reoxygenation (H/R) cellular models were used to characterize cuproptosis. Multi-omics profiling, molecular docking, and CTR1 (encoded by SLC31A1)-specific siRNA knockdown were used to explore the mechanism of action of Schisandrin B (SchB).

Single-cell RNA sequencing of murine ischemia-reperfusion (I/R) kidneys revealed that cuproptosis was a predominant RCD modality, accounting for approximately one-third of all regulated cell death events in renal tubular epithelial cells (RTECs). This finding was corroborated in human AKI biopsies and in murine I/R kidneys, where the key cuproptosis proteins ferredoxin 1 (FDX1) and copper transporter 1 (CTR1) were markedly upregulated, accompanied by significant copper accumulation and tubule injury. Under the tested conditions, SchB exhibited protective effects at least comparable to those of the classical copper chelator tetrathiomolybdate (TTM) in attenuating copper-dependent cytotoxicity in vitro. SchB-regulated differentially expressed genes were significantly enriched in glutathione metabolism, p53 signaling, cellular senescence, and PI3K-Akt pathways. Molecular docking predicted a direct interaction between SchB and CTR1 (binding energy -5.1 kcal/mol)siRNA-mediated depletion of CTR1 partially abolished the protective effects of SchB against copper-induced RTEC death, indicating that CTR1 may be required, at least in part, for SchB-induced cytoprotection in RTECs.

This study identifies cuproptosis as a predominant and previously unrecognized RCD pathway in ischemic AKI. SchB inhibits cuproptosis in a CTR1-dependent manner. These findings provide a preclinical rationale for further investigation of this natural product as a potential therapeutic candidate for ischemic kidney disease.