Abstract

Ochratoxin A (OTA) is a widespread nephrotoxic mycotoxin that contaminates cereal grains and feed, posing serious threats to animal health and food safety. Although curcumin has been reported to exert protective biological activities, it remains unclear whether its protection against OTA-induced renal epithelial injury is mediated by broad transcriptomic reversal or by selective regulation of key survival pathways. This study investigated the protective effect of curcumin against OTA-induced apoptosis in porcine renal epithelial (PK-15) cells and explored the underlying molecular mechanism using transcriptome sequencing combined with molecular validation. PK-15 cells were treated with 8 μg/mL OTA (approximately 19.8 μmol/L), 10 μmol/L curcumin, or their combination. Cell viability, LDH release, apoptotic morphology, mitochondrial membrane potential (ΔΨm), and apoptosis rate were assessed by CCK-8, LDH assay, Hoechst 33342 staining, JC-1 staining, and flow cytometry. Transcriptome sequencing was performed to identify global gene expression changes and key signaling pathways, followed by qRT-PCR and Western blot validation of apoptosis-related factors and the PI3K/AKT/mTOR pathway. OTA markedly reduced cell viability, increased LDH release, induced nuclear condensation and apoptotic body formation, and decreased ΔΨm. Transcriptome analysis revealed that OTA caused extensive transcriptional dysregulation (11,707 differentially expressed genes), whereas curcumin selectively modulated 498 genes, of which 380 overlapped with OTA-responsive genes. KEGG enrichment identified the PI3K-Akt signaling pathway as a key regulatory target. At the mRNA level, OTA upregulated Bax and Caspase-3 and downregulated Bcl-2; corresponding changes were observed at the protein level, and curcumin reversed these effects. Furthermore, OTA reduced the mRNA levels of PI3K, AKT, and mTOR and the protein abundance of PI3K, p-AKT, and mTOR, whereas curcumin partially restored these changes. In conclusion, curcumin alleviates OTA-induced mitochondrial apoptosis in PK-15 cells mainly by restoring PI3K/AKT/mTOR-associated survival signaling and Bcl-2/Bax/Caspase-3 balance rather than by broadly reversing the entire transcriptomic disturbance. These findings provide mechanistic insight into curcumin-mediated protection against OTA-induced renal epithelial toxicity.

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