title: The O-glycosylated ectodomain of FXYD5 impairs adhesion by disrupting cell-cell trans-dimerization of Na,K-ATPase β1 subunits.
abstract: FXYD5 (also known as dysadherin), a regulatory subunit of the Na,K-ATPase, impairs intercellular adhesion by a poorly understood mechanism. Here, we determined whether FXYD5 disrupts the trans-dimerization of Na,K-ATPase molecules located in neighboring cells. Mutagenesis of the Na,K-ATPase β1 subunit identified four conserved residues, including Y199, that are crucial for the intercellular Na,K-ATPase trans-dimerization and adhesion. Modulation of expression of FXYD5 or of the β1 subunit with intact or mutated β1-β1 binding sites demonstrated that the anti-adhesive effect of FXYD5 depends on the presence of Y199 in the β1 subunit. Immunodetection of the plasma membrane FXYD5 was prevented by the presence of O-glycans. Partial FXYD5 deglycosylation enabled antibody binding and showed that the protein level and the degree of O-glycosylation were greater in cancer than in normal cells. FXYD5-induced impairment of adhesion was abolished by both genetic and pharmacological inhibition of FXYD5 O-glycosylation. Therefore, the extracellular O-glycosylated domain of FXYD5 impairs adhesion by interfering with intercellular β1-β1 interactions, suggesting that the ratio between FXYD5 and α1-β1 heterodimer determines whether the Na,K-ATPase acts as a positive or negative regulator of intercellular adhesion.
authors.affiliation: Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90095, USA.
authors.forename: Elmira
authors.initials: E
authors.lastname: Tokhtaeva
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Haying
authors.initials: H
authors.lastname: Sun
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Nimrod
authors.initials: N
authors.lastname: Deiss-Yehiely
authors.affiliation: Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90095, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wen
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Pritin N
authors.initials: PN
authors.lastname: Soni
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA Instituto de Biología y Medicina Experimental (CONICET-FIBYME), Buenos Aires C1418ADN, Argentina.
authors.forename: Nieves M
authors.identifier: 0000-0002-3270-9140
authors.initials: NM
authors.lastname: Gabrielli
authors.affiliation: Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90095, USA Department of Pediatrics, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Marcus
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Ridge
authors.affiliation: Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90095, USA.
authors.forename: George
authors.initials: G
authors.lastname: Sachs
authors.affiliation: Instituto de Biología y Medicina Experimental (CONICET-FIBYME), Buenos Aires C1418ADN, Argentina.
authors.forename: Mónica
authors.initials: M
authors.lastname: Vazquez-Levin
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Sznajder
authors.affiliation: Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90095, USA.
authors.forename: Olga
authors.initials: O
authors.lastname: Vagin
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA lauradada@northwestern.edu.
authors.forename: Laura A
authors.identifier: 0000-0003-0474-718X
authors.initials: LA
authors.lastname: Dada
mesh_terms: D000072283:A549 Cells; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D000918:Antibody Specificity; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D007473:Ion Channels; D061985:Madin Darby Canine Kidney Cells; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins; D009363:Neoplasm Proteins / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000596:Amino Acids; C451410:FXYD5 protein, human; D007473:Ion Channels; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D021122:Protein Subunits; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Cell adhesion; Cell–cell interaction; Epithelial cell adhesion molecule; Epithelium; FXYD5; Na,K-ATPase; O-glycosylation