title: Suppression of caspase-3-dependent proteolytic activation of protein kinase C delta by small interfering RNA prevents MPP+-induced dopaminergic degeneration.
abstract: The cellular mechanisms underlying the neurodegenerative process in Parkinson's disease are not well understood. Using RNA interference (RNAi), we demonstrate that caspase-3-dependent proteolytic activation of protein kinase Cdelta (PKCdelta) contributes to the degenerative process in dopaminergic neurons. The Parkinsonian toxin MPP(+) activated caspase-3 and proteolytically cleaved PKCdelta into catalytic and regulatory subunits, resulting in persistent kinase activation in mesencephalic dopaminergic neuronal cells. The caspase-3 inhibitor Z-DEVD-FMK and the caspase-9 inhibitor Z-LEHD-FMK effectively blocked MPP(+)-induced PKCdelta proteolytic activation. To characterize the functional role of PKCdelta activation in MPP(+)-induced dopaminergic cell death, RNAi-mediated gene knockdown was performed. Among four siRNAs designed against PKCdelta, two specifically suppressed PKCdelta expression. The application of siRNA abolished the MPP(+)-induced PKCdelta activation, DNA fragmentation, and tyrosine hydroxylase (TH)-positive neuronal loss. Together, these results suggest that proteolytic activation of PKCdelta may be a critical downstream event in the degenerative process of Parkinson's disease.
authors.affiliation: Parkinson's Disorder Research Laboratory, Department of Biomedical Sciences, Iowa State University, Ames, IA 50011-1250, USA.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Yang
authors.forename: Siddharth
authors.initials: S
authors.lastname: Kaul
authors.forename: Danhui
authors.initials: D
authors.lastname: Zhang
authors.forename: Vellareddy
authors.initials: V
authors.lastname: Anantharam
authors.forename: Anumantha G
authors.initials: AG
authors.lastname: Kanthasamy
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000037:antagonists & inhibitors / Q000633:toxicity; D000818:Animals; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000096:biosynthesis / Q000235:genetics; D002460:Cell Line; D004298:Dopamine / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D009410:Nerve Degeneration / Q000139:chemically induced / Q000201:enzymology* / Q000517:prevention & control*; D010447:Peptide Hydrolases / Q000096:biosynthesis / Q000235:genetics; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D051745:Protein Kinase C-delta; D034741:RNA, Small Interfering / Q000494:pharmacology*; D051381:Rats
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D010447:Peptide Hydrolases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D015655:1-Methyl-4-phenylpyridinium; D004298:Dopamine