title: Cleavage and cell adhesion properties of human epithelial cell adhesion molecule (HEPCAM).
abstract: Human epithelial cell adhesion molecule (HEPCAM) is a tumor-associated antigen frequently expressed in carcinomas, which promotes proliferation after regulated intramembrane proteolysis. Here, we describe extracellular shedding of HEPCAM at two α-sites through a disintegrin and metalloprotease (ADAM) and at one β-site through BACE1. Transmembrane cleavage by γ-secretase occurs at three γ-sites to generate extracellular Aβ-like fragments and at two ϵ-sites to release human EPCAM intracellular domain HEPICD, which is efficiently degraded by the proteasome. Mapping of cleavage sites onto three-dimensional structures of HEPEX cis-dimer predicted conditional availability of α- and β-sites. Endocytosis of HEPCAM warrants acidification in cytoplasmic vesicles to dissociate protein cis-dimers required for cleavage by BACE1 at low pH values. Intramembrane cleavage sites are accessible and not part of the structurally important transmembrane helix dimer crossing region. Surprisingly, neither chemical inhibition of cleavage nor cellular knock-out of HEPCAM using CRISPR-Cas9 technology impacted the adhesion of carcinoma cell lines. Hence, a direct function of HEPCAM as an adhesion molecule in carcinoma cells is not supported and appears to be questionable.
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center.
authors: Thanos
authors: T
authors: Tsaktanis
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center.
authors: Heidi
authors: H
authors: Kremling
authors: the Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia.
authors: Miha
authors: M
authors: Pavšič
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center.
authors: Ricarda
authors: R
authors: von Stackelberg
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center.
authors: Brigitte
authors: B
authors: Mack
authors: the DZNE-German Center for Neurodegenerative Diseases, Feodor-Lynen-Strasse 17, 81377 Munich, Germany.
authors: Akio
authors: A
authors: Fukumori
authors: the DZNE-German Center for Neurodegenerative Diseases, Feodor-Lynen-Strasse 17, 81377 Munich, Germany, Biomedical Center, Biochemistry.
authors: Harald
authors: H
authors: Steiner
authors: Institute of Anatomy and Cell Biology, Department I.
authors: Franziska
authors: F
authors: Vielmuth
authors: Institute of Anatomy and Cell Biology, Department I.
authors: Volker
authors: V
authors: Spindler
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center.
authors: Zhe
authors: Z
authors: Huang
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, the Munich Center for Neurosciences, LMU Biocenter, AMGEN Scholars Programme, Ludwig-Maximilians-Universität Munich, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany, and.
authors: Jasmine
authors: J
authors: Jakubowski
authors: the Department for General, Visceral, and Pediatric Surgery, University Hospital and Medical Faculty of the Heinrich-Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany.
authors: Nikolas H
authors: NH
authors: Stoecklein
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center.
authors: Elke
authors: E
authors: Luxenburger
authors: Clinic for Radiotherapy and Radiation Oncology, and the Clinical Cooperation Group Personalized Radiotherapy of Head and Neck Tumors, Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany.
authors: Kirsten
authors: K
authors: Lauber
authors: the Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia.
authors: Brigita
authors: B
authors: Lenarčič
authors: From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Olivier.gires@med.uni-muenchen.de.
authors: Olivier
authors: O
authors: Gires
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D001665:Binding Sites; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D004705:Endocytosis; D000071858:Epithelial Cell Adhesion Molecule; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D059748:Proteolysis
chemical_list: D000596:Amino Acids; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D000071858:Epithelial Cell Adhesion Molecule; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human
keywords: ADAM; cell adhesion; epithelial cell adhesion molecule (EPCAM); proteolysis; β-secretase 1 (BACE1)