Parkinsonian mimetics induce aspects of unfolded protein response in death of dopaminergic neurons.
Genes associated with Parkinson's disease (PD) have suggested a role for ubiquitin-proteasome dysfunction and aberrant protein degradation in this disorder. Inasmuch as oxidative stress has also been implicated in PD, the present study examined transcriptional changes mediated by the Parkinsonism-inducing neurotoxins 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpyridinium (MPP+) in a dopaminergic cell line. Microarray analysis of RNA isolated from toxin treated samples revealed that the stress-induced transcription factor CHOP/Gadd153 was dramatically up-regulated by both 6-OHDA and MPP+. Treatment with 6-OHDA also induced a large number of genes involved in endoplasmic reticulum stress and unfolded protein response (UPR) such as ER chaperones and elements of the ubiquitin-proteasome system. Reverse transcription-PCR, Western blotting, and immunocytochemical approaches were used to quantify and temporally order the UPR pathways involved in neurotoxin-induced cell death. 6-OHDA, but not MPP+, significantly increased hallmarks of UPR such as BiP, c-Jun, and processed Xbp1 mRNA. Both toxins increased the phosphorylation of UPR proteins, PERK and eIF2 alpha, but only 6-OHDA increased phosphorylation of c-Jun. Thus, 6-OHDA is capable of triggering multiple pathways associated with UPR, whereas MPP+ exhibits a more restricted response. The involvement of UPR in these widely used neurotoxin models supports the role of ubiquitin-proteasome pathway dysfunction in PD.
Holtz
William Andrew
WA
Anatomy and Neurobiology Department, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
O'Malley
Karen Laurel
KL
D015655:1-Methyl-4-phenylpyridinium / Q000494:pharmacology; D015153:Blotting, Western; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D004298:Dopamine / Q000031:analogs & derivatives* / Q000502:physiology*; D004622:Embryo, Mammalian; D004625:Embryo, Nonmammalian; D004721:Endoplasmic Reticulum / Q000502:physiology; D000091342:Endoplasmic Reticulum Chaperone BiP; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006360:Heat-Shock Proteins; D007150:Immunohistochemistry; D008636:Mesencephalon; D018832:Molecular Chaperones / Q000235:genetics; D009097:Multienzyme Complexes / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D016627:Oxidopamine / Q000494:pharmacology; D010302:Parkinson Disease, Secondary / Q000139:chemically induced*; D017553:Phosphorus Compounds; D046988:Proteasome Endopeptidase Complex; D017510:Protein Folding; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics; D025801:Ubiquitin / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism
D015655:1-Methyl-4-phenylpyridinium; D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; D020169:Caspases; D003546:Cysteine Endopeptidases; D004268:DNA-Binding Proteins; D004298:Dopamine; D000091342:Endoplasmic Reticulum Chaperone BiP; D015852:Eukaryotic Initiation Factor-2; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D016627:Oxidopamine; D017553:Phosphorus Compounds; D046988:Proteasome Endopeptidase Complex; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D051742:Transcription Factor CHOP; D014157:Transcription Factors; D025801:Ubiquitin; D019892:eIF-2 Kinase; C059557:dopamine, Gly-Pro-amide-; C013196:phosphoryl chloride