title: Occludin S408 phosphorylation regulates tight junction protein interactions and barrier function.
abstract: Although the C-terminal cytoplasmic tail of the tight junction protein occludin is heavily phosphorylated, the functional impact of most individual sites is undefined. Here, we show that inhibition of CK2-mediated occludin S408 phosphorylation elevates transepithelial resistance by reducing paracellular cation flux. This regulation requires occludin, claudin-1, claudin-2, and ZO-1. S408 dephosphorylation reduces occludin exchange, but increases exchange of ZO-1, claudin-1, and claudin-2, thereby causing the mobile fractions of these proteins to converge. Claudin-4 exchange is not affected. ZO-1 domains that mediate interactions with occludin and claudins are required for increases in claudin-2 exchange, suggesting assembly of a phosphorylation-sensitive protein complex. Consistent with this, binding of claudin-1 and claudin-2, but not claudin-4, to S408A occludin tail is increased relative to S408D. Finally, CK2 inhibition reversed IL-13-induced, claudin-2-dependent barrier loss. Thus, occludin S408 dephosphorylation regulates paracellular permeability by remodeling tight junction protein dynamic behavior and intermolecular interactions between occludin, ZO-1, and select claudins, and may have therapeutic potential in inflammation-associated barrier dysfunction.
authors.affiliation: Department of Pathology, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Raleigh
authors.forename: Devin M
authors.initials: DM
authors.lastname: Boe
authors.forename: Dan
authors.initials: D
authors.lastname: Yu
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Weber
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Marchiando
authors.forename: Emily M
authors.initials: EM
authors.lastname: Bradford
authors.forename: Yingmin
authors.initials: Y
authors.lastname: Wang
authors.forename: Licheng
authors.initials: L
authors.lastname: Wu
authors.forename: Eveline E
authors.initials: EE
authors.lastname: Schneeberger
authors.forename: Le
authors.initials: L
authors.lastname: Shen
authors.forename: Jerrold R
authors.initials: JR
authors.lastname: Turner
mesh_terms: D018938:Caco-2 Cells; D062445:Claudin-1; D062506:Claudin-4; D057167:Claudins; D004594:Electrophysiology; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D062793:Occludin; D010539:Permeability; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
chemical_list: C568108:CLDN1 protein, human; C491875:CLDN2 protein, human; C568157:CLDN4 protein, human; D062445:Claudin-1; D062506:Claudin-4; D057167:Claudins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D034741:RNA, Small Interfering; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein