title: Calystegine B3 as a specific inhibitor for cytoplasmic alpha-mannosidase, Man2C1.
abstract: Cytoplasmic α-mannosidase (Man2C1) has been implicated in non-lysosomal catabolism of free oligosaccharides derived from N-linked glycans accumulated in the cytosol. Suppression of Man2C1 expression reportedly induces apoptosis in various cell lines, but its molecular mechanism remains unclear. Development of a specific inhibitor for Man2C1 is critical to understanding its biological significance. In this study, we identified a plant-derived alkaloid, calystegine B(3), as a potent specific inhibitor for Man2C1 activity. Biochemical enzyme assay revealed that calystegine B(3) was a highly specific inhibitor for Man2C1 among various α-mannosidases prepared from rat liver. Consistent with this in vitro result, an in vivo experiment also showed that treatment of mammalian-derived cultured cells with this compound resulted in drastic change in both structure and quantity of free oligosaccharides in the cytosol, whereas no apparent change was seen in cell-surface oligosaccharides. Calystegine B(3) could thus serve as a potent tool for the development of a highly specific in vivo inhibitor for Man2C1.
authors.affiliation: Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kato
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Kumiko
authors.initials: K
authors.lastname: Ishii
authors.forename: Junichi
authors.initials: J
authors.lastname: Seino
authors.forename: Naoki
authors.initials: N
authors.lastname: Asano
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003593:Cytoplasm / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D008099:Liver / Q000166:cytology / Q000201:enzymology; D008297:Male; D008958:Models, Molecular; D008968:Molecular Conformation; D009662:Nortropanes / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012991:Solanaceous Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D043323:alpha-Mannosidase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D009662:Nortropanes; D012991:Solanaceous Alkaloids; C095613:calystegine B(2); D043323:alpha-Mannosidase