title: Sequential Amyloid-β Degradation by the Matrix Metalloproteases MMP-2 and MMP-9.
abstract: Matrix metalloproteases (MMPs) MMP-2 and MMP-9 have been implicated in the physiological catabolism of Alzheimer's amyloid-β (Aβ). Conversely, their association with vascular amyloid deposits, blood-brain barrier disruption, and hemorrhagic transformations after ischemic stroke also highlights their involvement in pathological processes. To better understand this dichotomy, recombinant human (rh) MMP-2 and MMP-9 were incubated with Aβ40 and Aβ42, and the resulting proteolytic fragments were assessed via immunoprecipitation and quantitative mass spectrometry. Both MMPs generated Aβ fragments truncated only at the C terminus, ending at positions 34, 30, and 16. Using deuterated homologues as internal standards, we observed limited and relatively slow degradation of Aβ42 by rhMMP-2, although the enzyme cleaved >80% of Aβ40 during the 1st h of incubation. rhMMP-9 was significantly less effective, particularly in degrading Aβ(1-42), although the targeted peptide bonds were identical. Using Aβ(1-34) and Aβ(1-30), we demonstrated that these peptides are also substrates for both MMPs, cleaving Aβ(1-34) to produce Aβ(1-30) first and Aβ(1-16) subsequently. Consistent with the kinetics observed with full-length Aβ, rhMMP-9 degraded only a minute fraction of Aβ(1-34) and was even less effective in producing Aβ(1-16). Further degradation of Aβ(1-16) by either MMP-2 or MMP-9 was not observed even after prolonged incubation times. Notably, all MMP-generated C-terminally truncated Aβ fragments were highly soluble and did not exhibit fibrillogenic properties or induce cytotoxicity in human cerebral microvascular endothelial or neuronal cells supporting the notion that these truncated Aβ species are associated with clearance mechanisms rather than being key elements in the fibrillogenesis process.
authors.affiliation: From the Departments of Pathology, the Neurovascular Research Laboratory, Institut de Recerca, 08035 Barcelona, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Hernandez-Guillamon
authors.affiliation: From the Departments of Pathology.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Mawhirt
authors.affiliation: Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016, the Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, New York 10016, and.
authors.forename: Steven
authors.initials: S
authors.lastname: Blais
authors.affiliation: the Neurovascular Research Laboratory, Institut de Recerca, 08035 Barcelona, Spain, the Neurovascular Unit, Neurology and Medicine Departments, Universitat Autònoma de Barcelona, Vall d'Hebron Hospital, 08035 Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Montaner
authors.affiliation: Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016, the Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, New York 10016, and.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Neubert
authors.affiliation: From the Departments of Pathology.
authors.forename: Agueda
authors.initials: A
authors.lastname: Rostagno
authors.affiliation: From the Departments of Pathology, Psychiatry, and jorge.ghiso@nyumc.org.
authors.forename: Jorge
authors.initials: J
authors.lastname: Ghiso
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D059748:Proteolysis; D011994:Recombinant Proteins / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D016229:Amyloid beta-Peptides; D011994:Recombinant Proteins; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9
keywords: Alzheimer disease; amyloid-beta (Aβ); clearance/catabolism; mass spectrometry (MS); matrix metalloproteinase (MMP); peptides; proteolysis