title: The metalloprotease disintegrin ADAM8. Processing by autocatalysis is required for proteolytic activity and cell adhesion.
abstract: ADAMs (a disintegrin and metalloprotease domains) are metalloprotease and disintegrin domain-containing transmembrane glycoproteins with proteolytic, cell adhesion, cell fusion, and cell signaling properties. ADAM8 was originally cloned from monocytic cells, and its distinct expression pattern indicates possible roles in both immunology and neuropathology. Here we describe our analysis of its biochemical properties. In transfected COS-7 cells, ADAM8 is localized to the plasma membrane and processed into two forms derived either by prodomain removal or as remnant protein comprising the extracellular region with the disintegrin domain at the N terminus. Proteolytic removal of the ADAM8 propeptide was completely blocked in mutant ADAM8 with a Glu(330) to Gln exchange (EQ-A8) in the Zn(2+) binding motif (HE(330)LGHNLGMSHD), arguing for autocatalytic prodomain removal. In co-transfection experiments, the ectodomain but not the entire MP domain of ADAM8 was able to remove the prodomain from EQ-ADAM8. With cells expressing ADAM8, cell adhesion to a substrate-bound recombinant ADAM8 disintegrin/Cys-rich domain was observed in the absence of serum, blocked by an antibody directed against the ADAM8 disintegrin domain. Soluble ADAM8 protease, consisting of either the metalloprotease domain or the complete ectodomain, cleaved myelin basic protein and a fluorogenic peptide substrate, and was inhibited by batimastat (BB-94, IC(50) approximately 50 nm) but not by recombinant tissue inhibitor of matrix metalloproteinases 1, 2, 3, and 4. Our findings demonstrate that ADAM8 processing by autocatalysis leads to a potential sheddase and to a form of ADAM8 with a function in cell adhesion.
authors.affiliation: Developmental Biology and Molecular Pathology, W7, Bielefeld University, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schlomann
authors.forename: Dirk
authors.initials: D
authors.lastname: Wildeboer
authors.forename: Ailsa
authors.initials: A
authors.lastname: Webster
authors.forename: Olga
authors.initials: O
authors.lastname: Antropova
authors.forename: Dagmar
authors.initials: D
authors.lastname: Zeuschner
authors.forename: C Graham
authors.initials: CG
authors.lastname: Knight
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: Docherty
authors.forename: Marc
authors.initials: M
authors.lastname: Lambert
authors.forename: Lisa
authors.initials: L
authors.lastname: Skelton
authors.forename: Harald
authors.initials: H
authors.lastname: Jockusch
authors.forename: Jörg W
authors.initials: JW
authors.lastname: Bartsch
mesh_terms: D051722:ADAM Proteins; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism* / Q000502:physiology; D001483:Base Sequence; D019556:COS Cells; D002384:Catalysis; D002448:Cell Adhesion / Q000502:physiology; D017931:DNA Primers; D006868:Hydrolysis; D008565:Membrane Proteins; D008666:Metalloendopeptidases / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D017931:DNA Primers; D008565:Membrane Proteins; D051722:ADAM Proteins; C489402:Adam8 protein, mouse; D008666:Metalloendopeptidases