Alpha-synuclein aggregation and Ser-129 phosphorylation-dependent cell death in oligodendroglial cells.
Multiple system atrophy is a neurodegenerative disorder characterized by accumulation of aggregated Ser-129-phosphorylated alpha-synuclein in oligodendrocytes. p25alpha is an oligodendroglial protein that potently stimulates alpha-synuclein aggregation in vitro. To model multiple system atrophy, we coexpressed human p25alpha and alpha-synuclein in the rat oligodendroglial cell line OLN-93 and observed a cellular response characterized by a fast retraction of microtubules from the cellular processes to the perinuclear region followed by a protracted development of apoptosis. This response was dependent on phosphorylation at Ser-129 in alpha-synuclein as demonstrated by site-directed mutagenesis. Treatment of the cells with the kinase inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H benzimidazole that targets kinases like casein kinase 2, and polo-like kinases abrogated the toxicity. The polo-like kinase inhibitor BI 2536 caused apoptosis in the model. Ser-129 phosphorylation was linked to the formation of phosphorylated oligomers detectable by immunoblotting, and their formation was inhibited by 2-dimethylamino-4,5,6,7-tetrabromo-1H benzimidazole. The process of microtubule retraction was also dependent on aggregation as demonstrated by the protective effect of treating the cells with the specific peptide inhibitor of alpha-synuclein aggregation ASI1D and the non-selective inhibitors Congo Red and baicalein. The fast microtubule retraction was followed by the development of the apoptotic markers: activated caspase-3, phosphatidylserine externalization, nuclear condensation, and fragmentation. These markers could all be blocked by the inhibitors of phosphorylation, aggregation, and caspase-3. Hence, the model predicts that both Ser-129 phosphorylation and aggregation control the toxic alpha-syn pathway in oligodendroglial cells and may represent therapeutic intervention points in multiple system atrophy.
Kragh
Christine L
CL
Department of Medical Biochemistry, University of Aarhus, DK-8000 Aarhus, Denmark, Lundbeck A/S, DK-2500 Valby, Denmark.
Lund
Louise B
LB
Febbraro
Fabia
F
Hansen
Hanne D
HD
Gai
Wei-Ping
WP
El-Agnaf
Omar
O
Richter-Landsberg
Christiane
C
Jensen
Poul Henning
PH
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death; D002460:Cell Line; D003224:Congo Red / Q000494:pharmacology; D044950:Flavanones / Q000494:pharmacology; D008856:Microscopy, Fluorescence / Q000379:methods; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D009836:Oligodendroglia / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D012694:Serine / Q000737:chemistry*; D051844:alpha-Synuclein / Q000378:metabolism*
D044950:Flavanones; D051844:alpha-Synuclein; D003224:Congo Red; D012694:Serine; C006680:baicalein; D053148:Caspase 3