title: Glyceraldehyde-3-phosphate dehydrogenase in the extracellular space inhibits cell spreading.
abstract: The occurrence and the novel function of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the extracellular space were studied. The extracellular GAPDH with the same molecular mass as the intracellular GAPDH was detected in the conditioned medium of mammalian cultured cell lines such as COS-7, HEK293, MCF-7, HepG2, PC-12, and Neuro-2a cells. Western blot analysis represented the occurrence of GAPDH, but not alpha-tubulin (an intracellular marker protein), in the conditioned medium of COS-7 cells. Furthermore, GAPDH was found in rat serum. These results indicate that GAPDH was secreted outside of the cells. Addition of GAPDH to the cultured medium of COS-7, HEK293, and HepG2 cells allowed cells to undergo morphological changes. In COS-7 cells, the extracellular GAPDH inhibited cell spreading without influencing the cell growth. Western blot and immunofluorescent microscopy analyses revealed that the extracellular GAPDH bound to COS-7 cells in time- and dose-dependent manners. However, a mutant substituting Ser for Cys at position 151 of GAPDH resulted in no binding to the cells, no decreased cell-spreading efficiency and no cell morphological changes. These results indicate that the Cys151 was involved in the binding of GAPDH to cells and the GAPDH-inhibited cell spreading.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 5998531, Japan. yamaji@biochem.osakafu-u.ac.jp
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Yamaji
authors.forename: Emi
authors.initials: E
authors.lastname: Chatani
authors.forename: Naoki
authors.initials: N
authors.lastname: Harada
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inui
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Nakano
mesh_terms: D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion; D002460:Cell Line; D048430:Cell Shape / Q000187:drug effects; D002522:Chlorocebus aethiops; D005110:Extracellular Space / Q000201:enzymology*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000032:analysis* / Q000235:genetics / Q000502:physiology*; D006801:Humans; D051381:Rats; D011994:Recombinant Proteins / Q000032:analysis / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating)