title: Enhanced lysosomal pathology caused by beta-synuclein mutants linked to dementia with Lewy bodies.
abstract: Two missense mutations (P123H and V70M) of beta-synuclein (beta-syn), the homologue of alpha-syn, have been recently identified in dementia with Lewy bodies. However, the mechanism through which these mutations influence the pathogenesis of dementia with Lewy bodies is unclear. To investigate the role of the beta-syn mutations in neurodegeneration, each mutant was stably transfected into B103 neuroblastoma cells. Cells overexpressing mutated beta-syn had eosinophilic cytoplasmic inclusion bodies immunopositive for mutant beta-syn, and electron microscopy revealed that these cells were abundant in various cytoplasmic membranous inclusions resembling the histopathology of lysosomal storage disease. Consistent with these findings, the inclusion bodies were immunopositive for lysosomal markers, including cathepsin B, LAMP-2, GM2 ganglioside, and ATP13A2, which has recently been linked to PARK9. Notably, formation of these lysosomal inclusions was greatly stimulated by co-expression of alpha-syn, was dependent on the phosphorylation of alpha-syn at Ser-129, and was more efficient with the A53T familial mutant of alpha-syn compared with wild type. Furthermore, the inclusion formation in cells overexpressing mutant beta-syn and transfected with alpha-syn was significantly suppressed by treatment with autophagy-lysosomal inhibitors, which were associated with impaired clearance of syn proteins and enhanced apoptosis, indicating that formation of lysosomal inclusions might be protective. Collectively, the results demonstrated unambiguously that overexpression of beta-syn mutants (P123H and V70M) in neuroblastoma cells results in an enhanced lysosomal pathology. We suggest that these missense mutations of beta-syn might play a causative role in stimulating neurodegeneration.
authors.affiliation: Laboratory for Chemistry and Metabolism, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
authors.forename: Jianshe
authors.initials: J
authors.lastname: Wei
authors.affiliation: Laboratory for Chemistry and Metabolism, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
authors.forename: Masayo
authors.initials: M
authors.lastname: Fujita
authors.affiliation: Laboratory for Chemistry and Metabolism, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nakai
authors.affiliation: Laboratory for Chemistry and Metabolism, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Waragai
authors.affiliation: Laboratory for Molecular Neuropathology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Watabe
authors.affiliation: Choju Medical Institute, Fukushimura Hospital, Aichi 441-8124, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Akatsu
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California 92093-0624.
authors.forename: Edward
authors.initials: E
authors.lastname: Rockenstein
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California 92093-0624.
authors.forename: Eliezer
authors.initials: E
authors.lastname: Masliah
authors.affiliation: Laboratory for Chemistry and Metabolism, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan. Electronic address: mhashimoto@tmin.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hashimoto
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001343:Autophagy / Q000235:genetics; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D006801:Humans; D016631:Lewy Bodies / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure*; D020961:Lewy Body Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D020140:Lysosomal Storage Diseases, Nervous System / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008247:Lysosomes / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D051846:beta-Synuclein / Q000235:genetics / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D011506:Proteins; D051846:beta-Synuclein; C018589:lysosomal proteins