Apoptotic events induced by yessotoxin in myoblast cell lines from rat and mouse

This study reports apoptotic events after yessotoxin (YTX) exposure in L6 (rat) and BC3H1 (mouse) skeletal muscle myoblast cell lines. These cell lines are relevant targets to study the cytotoxic effect since this toxin has been reported as cardiotoxic. Mechanisms of action of YTX in multicellular organisms are not fully elucidated. Cell culture studies can contribute to find some of these mechanisms and trace the molecular pathways involved. The present work shows results from exposing cells to 100 nM purified YTX for 72 h. Morphological and biochemical changes characteristic of apoptotic cell death were evaluated in the two cell lines. Immunofluorescence and western blot techniques showed caspase-3 and caspase-9 activation. Western blot analysis of poly(ADP-ribose)-polymerase (PARP) confirmed caspase-3 activation in both cell lines. DNA fragmentation was not detected in these cell lines. This evidence reflect that oligonucleosomal DNA fragmentation is not a biochemical event that can be used as a definitive apoptotic marker in L6 and BC3H1 myoblast cell lines. The results indicate that the time-course and degree of apoptotic events induced by YTX depend on cell line sensitivity.