title: The epithelial cell adhesion molecule EpCAM is required for epithelial morphogenesis and integrity during zebrafish epiboly and skin development.
abstract: The aberrant expression of the transmembrane protein EpCAM is associated with tumor progression, affecting different cellular processes such as cell-cell adhesion, migration, proliferation, differentiation, signaling, and invasion. However, the in vivo function of EpCAM still remains elusive due to the lack of genetic loss-of-function studies. Here, we describe epcam (tacstd) null mutants in zebrafish. Maternal-zygotic mutants display compromised basal protrusive activity and epithelial morphogenesis in cells of the enveloping layer (EVL) during epiboly. In partial redundancy with E-cadherin (Ecad), EpCAM made by EVL cells is further required for cell-cell adhesion within the EVL and, possibly, for proper attachment of underlying deep cells to the inner surface of the EVL, thereby also affecting deep cell epiboly movements. During later development, EpCAM per se becomes indispensable for epithelial integrity within the periderm of the skin, secondarily leading to disrupted morphology of the underlying basal epidermis and moderate hyper-proliferation of skin cells. On the molecular level, EVL cells of epcam mutant embryos display reduced levels of membranous Ecad, accompanied by an enrichment of tight junction proteins and a basal extension of apical junction complexes (AJCs). Our data suggest that EpCAM acts as a partner of E-cadherin to control adhesiveness and integrity as well as plasticity and morphogenesis within simple epithelia. In addition, EpCAM is required for the interaction of the epithelia with underlying cell layers.
authors.affiliation: Georges-Koehler-Laboratory, Max-Planck Institute of Immunobiology, Freiburg, Germany.
authors.forename: Krasimir
authors.initials: K
authors.lastname: Slanchev
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Carney
authors.forename: Marc P
authors.initials: MP
authors.lastname: Stemmler
authors.forename: Birgit
authors.initials: B
authors.lastname: Koschorz
authors.forename: Adam
authors.initials: A
authors.lastname: Amsterdam
authors.forename: Heinz
authors.initials: H
authors.lastname: Schwarz
authors.forename: Matthias
authors.initials: M
authors.lastname: Hammerschmidt
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000502:physiology*; D015820:Cadherins / Q000502:physiology; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000502:physiology*; D004625:Embryo, Nonmammalian; D000071858:Epithelial Cell Adhesion Molecule; D004848:Epithelium / Q000196:embryology / Q000254:growth & development*; D008562:Membrane Glycoproteins / Q000502:physiology*; D009024:Morphogenesis; D012867:Skin / Q000196:embryology / Q000254:growth & development*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000502:physiology*
chemical_list: D000951:Antigens, Neoplasm; D015820:Cadherins; D015815:Cell Adhesion Molecules; C524037:EpCAM protein, zebrafish; D000071858:Epithelial Cell Adhesion Molecule; D008562:Membrane Glycoproteins; D029961:Zebrafish Proteins