title: Systemic proteasome inhibition triggers neurodegeneration in a transgenic mouse model expressing human α-synuclein under oligodendrocyte promoter: implications for multiple system atrophy.
abstract: Multiple system atrophy (MSA) is a progressive late onset neurodegenerative α-synucleinopathy with unclear pathogenesis. Recent genetic and pathological studies support a central role of α-synuclein (αSYN) in MSA pathogenesis. Oligodendroglial cytoplasmic inclusions of fibrillar αSYN and dysfunction of the ubiquitin-proteasome system are suggestive of proteolytic stress in this disorder. To address the possible pathogenic role of oligodendroglial αSYN accumulation and proteolytic failure in MSA we applied systemic proteasome inhibition (PSI) in transgenic mice with oligodendroglial human αSYN expression and determined the presence of MSA-like neurodegeneration in this model as compared to wild-type mice. PSI induced open field motor disability in transgenic αSYN mice but not in wild-type mice. The motor phenotype corresponded to progressive and selective neuronal loss in the striatonigral and olivopontocerebellar systems of PSI-treated transgenic αSYN mice. In contrast no neurodegeneration was detected in PSI-treated wild-type controls. PSI treatment of transgenic αSYN mice was associated with significant ultrastructural alterations including accumulation of fibrillar human αSYN in the cytoplasm of oligodendroglia, which resulted in myelin disruption and demyelination characterized by increased g-ratio. The oligodendroglial and myelin pathology was accompanied by axonal degeneration evidenced by signs of mitochondrial stress and dysfunctional axonal transport in the affected neurites. In summary, we provide new evidence supporting a primary role of proteolytic failure and suggesting a neurodegenerative pathomechanism related to disturbed oligodendroglial/myelin trophic support in the pathogenesis of MSA.
authors.affiliation: Division of Neurobiology, Innsbruck Medical University, Innsbruck, Austria. nadia.stefanova@i-med.ac.at
authors.forename: Nadia
authors.initials: N
authors.lastname: Stefanova
authors.forename: Walter A
authors.initials: WA
authors.lastname: Kaufmann
authors.forename: Christian
authors.initials: C
authors.lastname: Humpel
authors.forename: Werner
authors.initials: W
authors.lastname: Poewe
authors.forename: Gregor K
authors.initials: GK
authors.lastname: Wenning
mesh_terms: D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000473:pathology; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism; D005106:Exploratory Behavior / Q000187:drug effects; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016253:Microscopy, Immunoelectron; D009043:Motor Activity / Q000187:drug effects; D018991:Myelin Proteolipid Protein / Q000235:genetics; D019636:Neurodegenerative Diseases / Q000139:chemically induced* / Q000473:pathology* / Q000503:physiopathology; D009836:Oligodendroglia / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009842:Oligopeptides / Q000633:toxicity*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase; D025801:Ubiquitin / Q000378:metabolism; D051844:alpha-Synuclein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D018991:Myelin Proteolipid Protein; D009842:Oligopeptides; D025801:Ubiquitin; D051844:alpha-Synuclein; C090535:benzyloxycarbonyl-isoleucyl-glutamyl(O-tert-butyl)-alanyl-leucinal; D014446:Tyrosine 3-Monooxygenase; D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D046988:Proteasome Endopeptidase Complex