Calpain-cleavage of alpha-synuclein: connecting proteolytic processing to disease-linked aggregation.
Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are both characterized pathologically by the presence of neuronal inclusions termed Lewy bodies (LBs). A common feature found in LBs are aggregates of alpha-synuclein (alpha-Syn), and although it is now recognized that alpha-Syn is the major building block for these toxic filaments, the mechanism of how this occurs remains unknown. In the present study, we demonstrate that proteolytic processing of alpha-Syn by the protease calpain I leads to the formation of aggregated high-molecular weight species and adoption of a beta-sheet structure. To determine whether calpain-cleavage of alpha-Syn occurs in PD and DLB, we designed site-directed calpain-cleavage antibodies to alpha-Syn and tested their utility in several animal model systems. Detection of calpain-cleaved alpha-Syn was evident in mouse models of cerebral ischemia and PD and in a Drosophila model of PD. In the human PD and DLB brain, calpain-cleaved alpha-Syn antibodies immunolabeled LBs and neurites in the substantia nigra. Moreover, calpain-cleaved alpha-Syn fragments identified within LBs colocalized with activated calpain in neurons of the PD and DLB brains. These findings suggest that calpain I may participate in the disease-linked aggregation of alpha-Syn in various alpha-synucleinopathies.
Dufty
Brian M
BM
Department of Biology, Boise State University, Boise, ID 83725, USA.
Warner
Lisa R
LR
Hou
Sheng T
ST
Jiang
Susan X
SX
Gomez-Isla
Teresa
T
Leenhouts
Kristen M
KM
Oxford
Julia T
JT
Feany
Mel B
MB
Masliah
Eliezer
E
Rohn
Troy T
TT
D000368:Aged; D000818:Animals; D019540:Area Under Curve; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism*; D045744:Cell Line, Tumor; D004330:Drosophila; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D020961:Lewy Body Disease / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008875:Middle Aged; D009474:Neurons / Q000378:metabolism; D010300:Parkinson Disease / Q000378:metabolism* / Q000473:pathology; D017433:Protein Structure, Secondary; D051844:alpha-Synuclein / Q000737:chemistry / Q000378:metabolism*
D051844:alpha-Synuclein; D002154:Calpain