title: 6-Hydroxydopamine induces dopaminergic cell degeneration via a caspase-9-mediated apoptotic pathway that is attenuated by caspase-9dn expression.
abstract: This study showed that primary dopaminergic neurons or the dopaminergic cell line MN9D, when exposed to 15 min of the parkinsonian toxin 6-hydroxydopamine (6-OHDA) in the range of 30-100 microM, underwent delayed degeneration and exhibited hallmarks of apoptosis. These results, along with the absence of any increase in lactate dehydrogenase (LDH) release from the degenerated cells, imply that apoptosis was the dominant mode of cell death. Moreover, a distinct elevation in the measured cellular activities of caspase-9 and -3 but not of caspase-8 points to the caspase-9/caspase-3 cascade as the predominant apoptotic pathway in the degeneration of dopaminergic neurons and MN9D cells. In addition, the presence of caspase-9 or -3 peptide inhibitors but not of caspase-8 inhibitor attenuated cell death significantly, supporting the notion that only the intrinsic apoptotic pathway is utilized to achieve cell death. Finally, overexpression of a mutant caspase-9 with dominant negative phenotype (caspase-9dn) in MN9D cells and primary dopaminergic neurons via the adenovirus and adenoassociated virus gene delivery system, respectively, conferred marked increases in tolerance to the toxicity of 6-OHDA. These results point to the intrinsic caspase-9/caspase-3 cascade as the predominant signaling pathway underlying dopaminergic cell death induced by 6-OHDA and suggest that gene delivery of caspase-9dn can attenuate this pathway and its degenerative consequences.
authors.affiliation: Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Liang
authors.forename: Anthony K F
authors.initials: AK
authors.lastname: Liou
authors.forename: Yunmin
authors.initials: Y
authors.lastname: Ding
authors.forename: Guodong
authors.initials: G
authors.lastname: Cao
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiao
authors.forename: Ruth G
authors.initials: RG
authors.lastname: Perez
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005455:Fluorescent Antibody Technique / Q000379:methods; D005786:Gene Expression Regulation / Q000502:physiology; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D009154:Mutation; D009410:Nerve Degeneration / Q000139:chemically induced* / Q000517:prevention & control; D009842:Oligopeptides / Q000494:pharmacology; D016627:Oxidopamine / Q000633:toxicity*; D051381:Rats; D013778:Tetrazolium Salts; D013997:Time Factors; D014162:Transfection / Q000379:methods; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D013778:Tetrazolium Salts; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C403753:benzyloxycarbonyl-isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; C403754:benzyloxycarbonyl-leucyl-glutamyl-histidyl-aspartic acid fluoromethyl ketone; C059087:2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; D005680:gamma-Aminobutyric Acid; D016627:Oxidopamine; D007770:L-Lactate Dehydrogenase; D014446:Tyrosine 3-Monooxygenase; C505410:Casp3 protein, rat; C505528:Casp8 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D004298:Dopamine