Rescue from death but not from functional impairment: caspase inhibition protects dopaminergic cells against 6-hydroxydopamine-induced apoptosis but not against the loss of their terminals.
Despite the identification of several mutations in familial Parkinson's disease (PD), the underlying mechanisms of dopaminergic neuronal loss in idiopathic PD are still unknown. To study whether caspase-dependent apoptosis may play a role in the pathogenesis of PD, we examined 6-hydroxydopamine (6-OHDA) toxicity in dopaminergic SH-SY5Y cells and in embryonic dopaminergic mesencephalic cultures. 6-OHDA induced activation of caspases 3, 6 and 9, chromatin condensation and cell death in SH-SY5Y cells. The caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-(O-methyl)fluoromethylketone (zVAD-fmk) or adenovirally mediated ectopic expression of the X-chromosomal inhibitor of apoptosis protein (XIAP) blocked caspase activation and prevented death of SH-SY5Y cells. Similarly, zVAD-fmk provided protection from 6-OHDA-induced loss of tyrosine hydroxylase-positive neurones in mesencephalic cultures. In contrast, zVAD-fmk failed to protect mesencephalic dopaminergic neurones from 6-OHDA-induced loss of neurites and reduction of [(3)H]dopamine uptake. These data suggest that, although caspase inhibition provides protection from 6-OHDA-induced death of dopaminergic neurones, the neurones may remain functionally impaired.
von Coelln
R
R
Neurodegeneration Laboratory, Department of Neurology and Medical School, Tübingen, Germany.
Kügler
S
S
Bähr
M
M
Weller
M
M
Dichgans
J
J
Schulz
J B
JB
D000256:Adenoviridae / Q000235:genetics; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018014:Gene Transfer Techniques; D006801:Humans; D008636:Mesencephalon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016501:Neurites / Q000187:drug effects; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016627:Oxidopamine / Q000037:antagonists & inhibitors / Q000633:toxicity; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000494:pharmacology; D051381:Rats; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D051636:X-Linked Inhibitor of Apoptosis Protein
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D011506:Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D016627:Oxidopamine; D014446:Tyrosine 3-Monooxygenase; D020169:Caspases; D004298:Dopamine