title: Tumour necrosis factor alpha-converting enzyme mediates ectodomain shedding of Vps10p-domain receptor family members.
abstract: Several transmembrane molecules are cleaved at juxtamembrane extracellular sites leading to shedding of ectodomains. We analysed shedding of members of the Vps10p-D (Vps10p domain; where Vps is vacuolar protein sorting) family of neuronal type-I receptors with partially overlapping functions, and additional proteolytic events initiated by the shedding. When transfected into CHO (Chinese-hamster ovary) cells (CHO-K1), sorCS1a-sorCS1c isoforms were shed at high rates (approximately 0.61% x min(-1)) that were increased approx. 3-fold upon stimulation with phorbol ester. sorCS1c identified in the cultured neuroblastoma cell line SH-SY5Y was shed similarly. In CHO-K1 transfectants, constitutive and stimulated shedding of sorCS3 also occurred at high rates (0.29% and 1.03% x min(-1)). By comparison, constitutive and stimulated shedding of sorLA occurred at somewhat lower rates (0.07% and 0.48% x min(-1)), whereas sorCS2 and sortilin were shed at very low rates even when stimulated (approximately 0.01% x min(-1)). Except for sorCS2, shedding of the receptors was dramatically reduced in mutant CHO cells (CHO-M2) devoid of active TACE (tumour necrosis factor alpha-converting enzyme), demonstrating that this enzyme accounts for most sheddase activity. The release of sorCS1 and sorLA ectodomains initiated rapid cleavage of the membrane-tethered C-terminal stubs that accumulated only in the presence of gamma-secretase inhibitors. Purified shed sorLA bound several ligands similarly to the entire luminal domain of the receptor, including PDGF-BB (platelet-derived growth factor-BB) and amyloid-beta precursor protein. In addition, PDGF-BB also bound to the luminal domains of sorCS1 and sorCS3. The results suggest that ectodomains shed from a subset of Vps10p-D receptors can function as carrier proteins.
authors.affiliation: Institute of Medical Biochemistry, MIND Center, Ole Worms Allé, Building 1170, University of Aarhus, 8000 Arhus C, Denmark.
authors.forename: Guido
authors.initials: G
authors.lastname: Hermey
authors.forename: Susanne S
authors.initials: SS
authors.lastname: Sjøgaard
authors.forename: Claus Munck
authors.initials: CM
authors.lastname: Petersen
authors.forename: Anders
authors.initials: A
authors.lastname: Nykjaer
authors.forename: Jørgen
authors.initials: J
authors.lastname: Gliemann
mesh_terms: D051722:ADAM Proteins / Q000172:deficiency / Q000378:metabolism*; D000072198:ADAM17 Protein; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D006801:Humans; D026502:LDL-Receptor Related Proteins; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism*; D011973:Receptors, LDL / Q000737:chemistry / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000737:chemistry / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000737:chemistry*; D000099183:Sortilin
chemical_list: D051722:ADAM Proteins; D000072198:ADAM17 Protein; D033942:Adaptor Proteins, Vesicular Transport; D026502:LDL-Receptor Related Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D011973:Receptors, LDL; D018013:Receptors, Neuropeptide; D033921:Vesicular Transport Proteins; D000099183:Sortilin; C472780:SORCS1 protein, human; C509461:SORCS2 protein, human; C102582:SORL1 protein, human; C498347:SorCS3 protein, human; C000606462:ADAM17 protein, human