Cell surface colony-stimulating factor 1 can be cleaved by TNF-alpha converting enzyme or endocytosed in a clathrin-dependent manner.
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.
Horiuchi
Keisuke
K
Department of Anti-Aging Orthopedic Research, Keio University, School of Medicine, Tokyo, Japan. horiuchi@z3.keio.jp
Miyamoto
Takeshi
T
Takaishi
Hironari
H
Hakozaki
Akihiro
A
Kosaki
Naoto
N
Miyauchi
Yoshiteru
Y
Furukawa
Mitsuru
M
Takito
Jiro
J
Kaneko
Hironori
H
Matsuzaki
Kenichiro
K
Morioka
Hideo
H
Blobel
Carl P
CP
Toyama
Yoshiaki
Y
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
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