title: Cell surface colony-stimulating factor 1 can be cleaved by TNF-alpha converting enzyme or endocytosed in a clathrin-dependent manner.
abstract: CSF-1 is a hemopoietic growth factor, which plays an essential role in macrophage and osteoclast development. Alternative splice variants of CSF-1 are synthesized as soluble or membrane-anchored molecules, although membrane CSF-1 (mCSF-1) can be cleaved from the cell membrane to become soluble CSF-1. The activities involved in this proteolytic processing, also referred to as ectodomain shedding, remain poorly characterized. In the present study, we examined the properties of the mCSF-1 sheddase in cell-based assays. Shedding of mCSF-1 was up-regulated by phorbol ester treatment and was inhibited by the metalloprotease inhibitors GM6001 and tissue inhibitor of metalloproteases 3. Moreover, the stimulated shedding of mCSF-1 was abrogated in fibroblasts lacking the TNF-alpha converting enzyme (TACE, also known as a disintegrin and metalloprotease 17) and was rescued by expression of wild-type TACE in these cells, strongly suggesting that the stimulated shedding is TACE dependent. Additionally, we observed that mCSF-1 is predominantly localized to intracellular membrane compartments and is efficiently internalized in a clathrin-dependent manner. These results indicate that the local availability of mCSF-1 is actively regulated by ectodomain shedding and endocytosis. This mechanism may have important implications for the development and survival of monocyte lineage cells.
authors.affiliation: Department of Anti-Aging Orthopedic Research, Keio University, School of Medicine, Tokyo, Japan. horiuchi@z3.keio.jp
authors.forename: Keisuke
authors.initials: K
authors.lastname: Horiuchi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Hironari
authors.initials: H
authors.lastname: Takaishi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hakozaki
authors.forename: Naoto
authors.initials: N
authors.lastname: Kosaki
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Miyauchi
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Furukawa
authors.forename: Jiro
authors.initials: J
authors.lastname: Takito
authors.forename: Hironori
authors.initials: H
authors.lastname: Kaneko
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Matsuzaki
authors.forename: Hideo
authors.initials: H
authors.lastname: Morioka
authors.forename: Carl P
authors.initials: CP
authors.lastname: Blobel
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000072198:ADAM17 Protein; D017398:Alternative Splicing / Q000187:drug effects / Q000502:physiology; D000818:Animals; D019556:COS Cells; D002273:Carcinogens / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002522:Chlorocebus aethiops; D002966:Clathrin / Q000378:metabolism*; D004151:Dipeptides / Q000494:pharmacology; D004705:Endocytosis / Q000502:physiology*; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D010010:Osteoclasts / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D017434:Protein Structure, Tertiary / Q000502:physiology; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism
chemical_list: D002273:Carcinogens; D002966:Clathrin; D004151:Dipeptides; D008565:Membrane Proteins; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D010703:Phorbol Esters; D011480:Protease Inhibitors; D019717:Tissue Inhibitor of Metalloproteinase-3; D016173:Macrophage Colony-Stimulating Factor; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606463:Adam17 protein, mouse