Nephrotoxicity of Fumonisin B1 and Ochratoxin A co-exposure is associated with Hippo/YAP1-mediated ferroptosis

Fumonisin B1 (FB1) and Ochratoxin A (OTA) are two nephrotoxic mycotoxins that frequently co-occur in feed and food. Ferroptosis, an iron-dependent form of programmed cell death, is involved in kidney injury. Hippo/YAP signalling pathway is involved in cell proliferation and ferroptosis. This study aims to investigate the role of the Hippo/YAP signalling pathway and ferroptosis in the nephrotoxicity induced by co-exposure to FB1 and OTA in mice and PK-15 cells. Results showed that co-exposure to FB1 and OTA significantly induced kidney injury as demonstrated by increasing histopathological lesions, kidney index, serum BUN, CRE and UA levels, decreasing PK-15 cell viabilities, increasing PK-15 cell LDH release and kidney injury molecule and inflammatory cytokine expression levels of kidney and PK-15 cells. RNA-seq analysis of PK-15 cells revealed that OTA and FB1 co-exposure identified 664 DEGs and enriched ferroptosis and Hippo signalling pathway of KEGG. FB1 and OTA co-exposure induced ROS production, decreased GSH content, increased MDA level, iron content, and 4-HNE expression, and increased ACSL4, LPCAT3 and HO-1 expressions, and decreased GPX4, SLC7A11 and FTH expressions. FB1 and OTA co-exposure increased YAP1, TEAD1, and LAST1 expressions, while concurrently reduced YAP1 and LAST1 phosphorylation levels. Knock-down ASCL4 attenuated nephrotoxicity induced by OTA and FB1 co-exposure. Knock-down YAP1 rescued the MDA and iron accumulation and GSH decreasing, inhibited ferroptosis, and alleviated OTA and FB1-induced nephrotoxicity. This study elucidates that YAP1 played a key role in OTA and FB1 co-exposure induced nephrotoxicity through regulating ferroptosis, providing targets against combination of OTA and FB1 exposure-induced nephrotoxicity.