title: The extracellular matrix protein MAGP-2 interacts with Jagged1 and induces its shedding from the cell surface.
abstract: Elastic fibers are composed of the protein elastin and a network of 10-12-nm microfibrils, which are composed of several glycoproteins, including fibrillin-1, fibrillin-2, and MAGP1/2 (microfibril-associated glycoproteins-1 and -2). Although fibrillins and MAGPs covalently associate, we find that the DSL (Delta/Serrate/LAG2) protein Jagged1, an activating ligand for Notch receptor signaling, also interacts with MAGP-2 in both yeast two-hybrid and coimmunoprecipitation studies. Interaction between Jagged1 and MAGP-2 requires the epidermal growth factor-like repeats of Jagged1. MAGP-2 was found complexed with the Jagged1 extracellular domain shed from 293T cells and COS-7 cells coexpressing full-length Jagged1 and MAGP-2. MAGP-2 shedding of the Jagged1 extracellular domain was decreased by the metalloproteinase hydroxamate inhibitor BB3103 implicating proteolysis in its release. Although MAGP-2 also interacted with the other DSL ligands, Jagged2 and Delta1, they were not found associated with MAGP-2 in the conditioned media, identifying differential effects of MAGP-2 on DSL ligand shedding. The related microfibrillar protein MAGP-1 was also found to interact with DSL ligands but, unlike MAGP-2, was unable to facilitate the shedding of Jagged1. Our findings suggest that in addition to its role in microfibrils, MAGP-2 may also affect cellular differentiation through modulating the Notch signaling pathway either by binding to cell surface DSL ligands or by facilitating release and/or stabilization of a soluble extracellular form of Jagged1.
authors.affiliation: Department of Medicine, Division of Pulmonary and Critical Care Medicine, Washington University, St. Louis, Missouri 63110, USA.
authors.forename: Leslie C
authors.initials: LC
authors.lastname: Nehring
authors.forename: Alison
authors.initials: A
authors.lastname: Miyamoto
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Hein
authors.forename: Gerry
authors.initials: G
authors.lastname: Weinmaster
authors.forename: J Michael
authors.initials: JM
authors.lastname: Shipley
mesh_terms: D051722:ADAM Proteins; D000072198:ADAM17 Protein; D000818:Animals; D000918:Antibody Specificity; D019556:COS Cells; D002135:Calcium-Binding Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003285:Contractile Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017077:Culture Media, Conditioned; D004815:Epidermal Growth Factor / Q000737:chemistry; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017353:Gene Deletion; D015870:Gene Expression; D007163:Immunosorbent Techniques; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism; D016296:Mutagenesis; D010446:Peptide Fragments / Q000378:metabolism; D000072260:RNA Splicing Factors; D000072099:Serrate-Jagged Proteins; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D002135:Calcium-Binding Proteins; D003285:Contractile Proteins; D017077:Culture Media, Conditioned; D016326:Extracellular Matrix Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins; D010446:Peptide Fragments; D000072260:RNA Splicing Factors; D000072099:Serrate-Jagged Proteins; C016598:microfibrillar protein; D004815:Epidermal Growth Factor; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein