title: Desmoglein endocytosis and desmosome disassembly are coordinated responses to pemphigus autoantibodies.
abstract: Desmosomes are adhesive intercellular junctions prominent in the skin and heart. Loss of desmosome function is associated with severe congenital and acquired disorders characterized by tissue fragility. Pemphigus vulgaris (PV) is an autoimmune disorder in which antibodies are directed against the desmosomal adhesion molecule Dsg3, resulting in severe mucosal erosions and epidermal blistering. To define the mechanisms by which Dsg3 autoantibodies disrupt keratinocyte adhesion, the fate of PV IgG and various desmosomal components was monitored in primary human keratinocytes exposed to PV patient IgG. PV IgG initially bound to keratinocyte cell surfaces and colocalized with desmosomal markers. Within 6 h after PV IgG binding to Dsg3, electron microscopy revealed that desmosomes were dramatically disrupted and keratinocyte adhesion was severely compromised. Immunofluorescence analysis indicated that PV IgG and Dsg3 were rapidly internalized from the cell surface in a complex with plakoglobin but not desmoplakin. Dsg3 internalization was associated with retraction of keratin filaments from cell-cell borders. Furthermore, the internalized PV IgG-Dsg3 complex colocalized with markers for both endosomes and lysosomes, suggesting that Dsg3 was targeted for degradation. Consistent with this possibility, biotinylation experiments demonstrated that soluble Dsg3 cell surface pools were rapidly depleted followed by loss of detergent-insoluble Dsg3. These findings demonstrate that Dsg3 endocytosis, keratin filament retraction, and the loss of keratinocyte cell-cell adhesion are coordinated responses to PV IgG.
authors.affiliation: Departments of Dermatology and Cell Biology, Emory University School of Medicine, Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, GA 30322, USA.
authors.forename: Cathárine C
authors.initials: CC
authors.lastname: Calkins
authors.forename: Shannon V
authors.initials: SV
authors.lastname: Setzer
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: Jennings
authors.forename: Susan
authors.initials: S
authors.lastname: Summers
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Tsunoda
authors.forename: Masayuki
authors.initials: M
authors.lastname: Amagai
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Kowalczyk
mesh_terms: D001323:Autoantibodies / Q000737:chemistry*; D019921:Biotinylation; D015153:Blotting, Western; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000737:chemistry; D051184:Desmoglein 3 / Q000737:chemistry; D051182:Desmogleins / Q000737:chemistry*; D003896:Desmosomes / Q000737:chemistry* / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004705:Endocytosis; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry; D015603:Keratinocytes / Q000378:metabolism; D007633:Keratins / Q000737:chemistry; D008247:Lysosomes / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008954:Models, Biological; D009092:Mucous Membrane / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010392:Pemphigus / Q000276:immunology*; D011485:Protein Binding; D012867:Skin / Q000378:metabolism; D019809:Streptavidin / Q000737:chemistry; D013314:Stress, Mechanical; D013997:Time Factors; D051185:gamma Catenin / Q000737:chemistry
chemical_list: D001323:Autoantibodies; D003598:Cytoskeletal Proteins; C071894:DSG3 protein, human; D051184:Desmoglein 3; D051182:Desmogleins; D003902:Detergents; D007074:Immunoglobulin G; D051185:gamma Catenin; D007633:Keratins; D019809:Streptavidin