Proteolytic cleavage of extracellular secreted {alpha}-synuclein via matrix metalloproteinases.
Although alpha-synuclein is the main structural component of the insoluble filaments that form Lewy bodies in Parkinson disease (PD), its physiological function and exact role in neuronal death remain poorly understood. In the present study, we examined the possible functional relationship between alpha-synuclein and several forms of matrix metalloproteinases (MMPs) in the human dopaminergic neuroblastoma (SK-N-BE) cell line. When SK-N-BE cells were transiently transfected with alpha-synuclein, it was secreted into the extracellular culture media, concomitantly with a significant decrease in cell viability. Also the addition of nitric oxide-generating compounds to the cells caused the secreted alpha-synuclein to be digested, producing a small fragment whose size was similar to that of the fragment generated during the incubation of alpha-synuclein with various MMPs in vitro. Among several forms of MMPs, alpha-synuclein was cleaved most efficiently by MMP-3, and MALDI-TOF mass spectra analysis showed that alpha-synuclein is cleaved from its C-terminal end with at least four cleavage sites within the non-Abeta component of AD amyloid sequence. Compared with the intact form, the protein aggregation of alpha-synuclein was remarkably facilitated in the presence of the proteolytic fragments, and the fragment-induced aggregates showed more toxic effect on cell viability. Moreover, the levels of MMP-3 were also found to be increased significantly in the rat PD brain model produced by the cerebral injection of 6-hydroxydopamine into the substantia nigra. The present study suggests that the extracellularly secreted alpha-synuclein could be processed via the activation of MMP-3 in a selective manner.
Sung
Jee Young
JY
Department of Biology, College of Science, Yonsei University, Seoul 120-749, Korea.
Park
Sung Min
SM
Lee
Choong-Hwan
CH
Um
Ji Won
JW
Lee
Hyun Jung
HJ
Kim
Jongsun
J
Oh
Young J
YJ
Lee
Seung-Taek
ST
Paik
Seung R
SR
Chung
Kwang Chul
KC
D000544:Alzheimer Disease / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000737:chemistry; D000818:Animals; D015153:Blotting, Western; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D002470:Cell Survival; D004396:Coloring Agents / Q000494:pharmacology; D003470:Culture Media; D004298:Dopamine / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007313:Insecta; D007700:Kinetics; D008297:Male; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D016627:Oxidopamine / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010300:Parkinson Disease / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013378:Substantia Nigra / Q000378:metabolism; D051843:Synucleins; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D051844:alpha-Synuclein
D016229:Amyloid beta-Peptides; D004396:Coloring Agents; D003470:Culture Media; D009419:Nerve Tissue Proteins; D009573:Nitrites; C497604:SNCA protein, human; C497606:Snca protein, rat; D051843:Synucleins; D013778:Tetrazolium Salts; D013844:Thiazoles; D051844:alpha-Synuclein; D009569:Nitric Oxide; D016627:Oxidopamine; D020782:Matrix Metalloproteinases; D019278:Matrix Metalloproteinase 3; C022616:thiazolyl blue; D010100:Oxygen; D004298:Dopamine