title: Matrix vesicles and media vesicles as nonclassical pathways for the secretion of m-Calpain from MC3T3-E1 cells.
abstract: Calpain was generally believed to exist and function only in the cytoplasm. However, m-calpain has now been detected in the extracellular spaces of some kinds of tissue. In this study, we demonstrated the existence of m-calpain in the medium surrounding MC3T3-E1 cultures, and its activity by zymography. At the same time, the amount of lactate dehydrogenase in medium of MC3T3-E1 culture was extremely low compared with other cell cultures, suggesting that m-calpain found in the culture medium of MC3T3-E1 cells originated mainly from active secretion. Moreover, the secretion of m-calpain was not blocked by brefeldin A, implying that m-calpain may be secreted by a nonclassical pathway. Recently, MC3T3-E1 has been reported to produce matrix vesicles and media vesicles, and we demonstrated m-calpain in these vesicles produced by MC3T3-E1 cultures. We therefore concluded that these vesicles are partly responsible for the secretion of m-calpain into the culture medium of MC3T3-E1 cells.
authors.affiliation: Department of Orthopedic Surgery, Faculty of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyoku, Kyoto 606-8507, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nishihara
authors.forename: Y
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: H
authors.initials: H
authors.lastname: Ishikawa
authors.forename: M
authors.initials: M
authors.lastname: Ohba
authors.forename: K
authors.initials: K
authors.lastname: Shimizu
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002154:Calpain / Q000032:analysis / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D017077:Culture Media, Conditioned / Q000032:analysis / Q000378:metabolism; D004792:Enzyme Precursors / Q000378:metabolism*; D005109:Extracellular Matrix / Q000201:enzymology; D006801:Humans; D015151:Immunoblotting; D007476:Ionophores / Q000494:pharmacology; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008744:Methylamines / Q000494:pharmacology; D051379:Mice; D008985:Monensin / Q000494:pharmacology; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D022142:Secretory Vesicles / Q000201:enzymology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D017077:Culture Media, Conditioned; D004792:Enzyme Precursors; D007476:Ionophores; D007527:Isoenzymes; D008744:Methylamines; D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A; D008985:Monensin; C027451:methylamine; D014700:Verapamil; D007770:L-Lactate Dehydrogenase; D002154:Calpain