Fumonisin B1 induces autophagic cell death via activation of ERN1-MAPK8/9/10 pathway in monkey kidney MARC-145 cells

Mycotoxins are secondary fungal metabolites that are capable of inducing a variety of toxic effects in animals and humans resulting from the consumption of the contaminated food. Understanding the mechanisms of the toxicities behind these mycotoxins is required to develop mechanism-based approach to counteract their toxic potential. Fumonisin B1 (FB1) is the most prevalent member of fumonisins that are a group of mycotoxins produced primarily by Fusarium verticillioides and Fusarium proliferatum. Kidney is one of the primary target organs for FB1 action. Using monkey kidney MARC-145 cells as an intro model, we found that FB1 induced caspase-independent programmed cell death accompanied with autophagy induction. Inhibition of autophagy by either chemical inhibitors or RNAi approach led to a significant reduction in cell death by FB1 exposure, indicating possible involvement of autophagy-mediated cell death in nephrotoxicity of FB1. Further mechanistic investigation revealed that activation of ERN1-MAPK8/9/10 axis played a critical role in autophagy induction and autophagy-mediated cell death by FB1 exposure. In addition, we demonstrated that disruption of sphingolipid metabolism was an apical event in FB1-induced ERN1-MAPK8/9/10-mediated autophagic cell death in MARC-145 cells. Lastly, we identified curcumin, a naturally occurring plant phenolic compound, as a possible anti-FB1 agent that can be used to protect kidney cells from FB1-induced cell death through inhibition of MAPK8/9/10 activation.