title: Occludin S471 Phosphorylation Contributes to Epithelial Monolayer Maturation.
abstract: Multiple organ systems require epithelial barriers for normal function, and barrier loss is a hallmark of diseases ranging from inflammation to epithelial cancers. However, the molecular processes regulating epithelial barrier maturation are not fully elucidated. After contact, epithelial cells undergo size-reductive proliferation and differentiate, creating a dense, highly ordered monolayer with high resistance barriers. We provide evidence that the tight junction protein occludin contributes to the regulation of epithelial cell maturation upon phosphorylation of S471 in its coiled-coil domain. Overexpression of a phosphoinhibitory occludin S471A mutant prevents size-reductive proliferation and subsequent tight junction maturation in a dominant manner. Inhibition of cell proliferation in cell-contacted but immature monolayers recapitulated this phenotype. A kinase screen identified G-protein-coupled receptor kinases (GRKs) targeting S471, and GRK inhibitors delayed epithelial packing and junction maturation. We conclude that occludin contributes to the regulation of size-reductive proliferation and epithelial cell maturation in a phosphorylation-dependent manner.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Bolinger
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Aniket
authors.identifier: 0000-0002-0599-4337
authors.initials: A
authors.lastname: Ramshekar
authors.affiliation: Vahlteich Medicinal Chemistry Core, Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Helen V
authors.initials: HV
authors.lastname: Waldschmidt
authors.affiliation: Vahlteich Medicinal Chemistry Core, Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Larsen
authors.affiliation: Departments of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Bewley
authors.affiliation: Departments of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Flanagan
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA dantonet@umich.edu.
authors.forename: David A
authors.initials: DA
authors.lastname: Antonetti
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D054768:G-Protein-Coupled Receptor Kinases / Q000378:metabolism*; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D062793:Occludin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D000072417:Protein Domains; D012694:Serine / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism*
chemical_list: C568985:OCLN protein, human; D062793:Occludin; D012694:Serine; D054768:G-Protein-Coupled Receptor Kinases