Cytotoxic responses in BC3H1 myoblast cell lines exposed to 1-desulfoyessotoxin

•1-Desulfoyessotoxin induces paraptosis-like cell death in BC3H1 myoblast cells.•The toxin induces activation of p38 MAPK kinase and increased expression of Hsp70.•The extra sulfate ester group at C-1 in YTX is not significant for in vitro toxicity. 1-Desulfoyessotoxin (1-dsYTX) is a desulfated polyether compound belonging to the yessotoxin group of marine toxins. This analogue has been detected in mussels. There are so far no reports on the mechanisms of action of 1-dsYTX in in vitro cell systems. This work evaluates cytotoxic responses in BC3H1 cells exposed to 100nM 1-dsYTX. The toxicity of 1-dsYTX seems to be similar to that of yessotoxin (YTX). 1-Desulfoyessotoxin induced morphological and biochemical traits typical of a non-apoptotic form of cell death resembling paraptosis. Treated BC3H1 cells showed extensive cytoplasmic vacuolation, enlargement of mitochondria and endoplasmic reticulum and lack of DNA fragmentation. Western blotting analysis revealed phosphorylation of the protein kinase p38 and involvement of the heat shock protein Hsp70. This activation suggests involvement of different signalling pathways for programmed cell death.