Maitotoxin induces calpain activation in SH-SY5Y neuroblastoma cells and cerebrocortical cultures.
Maitotoxin (MTX) is a highly potent marine toxin that activates both voltage-sensitive and receptor-operated calcium channels in the plasma membrane. This results in calcium overload that rapidly leads to cell death. We now report that maitotoxin (0.1-1 nM) induces calpain activation in both SH-SY5Y neuroblastoma cells and fetal rat cerebrocortical cultures. MTX-induced calpain activation was confirmed by the presence of autolytic fragmentation of both subunits of calpain. Secondly, the formation of calpain-produced alpha-spectrin breakdown products (150 and 145 kDa) was observed. We were also able to detect intracellular hydrolysis of a peptide substrate (succinyl-Leu-Leu-Val-Tyr-7-amido-4-methylcoumarin) by activated calpain in MTX-treated cells. Calpain inhibitors (calpain inhibitor I, MDL28170 and PD150606) inhibited spectrin breakdown and SLLVY-AMC hydrolysis in MTX-treated SY5Y cells. Our results suggest that (i) calpain is activated as a result of the maitotoxin-induced calcium influx; and (ii) coupling with the in situ calpain assays, maitotoxin would be a useful tool in investigating the physiologic and pathophysiologic roles of calpain in neuronal cells.
Wang
K K
KK
Laboratory of Neuro-biochemistry, Department of Neuroscience Therapeutics and Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, 2800 Plymouth Road, Ann Arbor, Michigan, 48105, USA.
Nath
R
R
Raser
K J
KJ
Hajimohammadreza
I
I
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D008387:Marine Toxins / Q000494:pharmacology*; D008727:Methotrexate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009474:Neurons / Q000201:enzymology*; D035964:Oxocins; D051381:Rats; D017207:Rats, Sprague-Dawley; D013049:Spectrin / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000095702:Polyether Toxins
D002118:Calcium; D002154:Calpain; D008387:Marine Toxins; D008727:Methotrexate; D035964:Oxocins; D013049:Spectrin; C020394:maitotoxin; D000095702:Polyether Toxins