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J Cell Sci. 2016 Jun 15;129(12):2394-406. doi: 10.1242/jcs.186148. Epub 2016 May 3.

The O-glycosylated ectodomain of FXYD5 impairs adhesion by disrupting cell-cell trans-dimerization of Na,K-ATPase β1 subunits.

Author information

1
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.
2
Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
3
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.
4
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.
5
Instituto de Biología y Medicina Experimental (CONICET-FIBYME), Buenos Aires C1418ADN, Argentina.
6
Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA lauradada@northwestern.edu.

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.

KEYWORDS:

Cell adhesion; Cell–cell interaction; Epithelial cell adhesion molecule; Epithelium; FXYD5; Na,K-ATPase; O-glycosylation

PMID:
27142834
PMCID:
PMC4920254
DOI:
10.1242/jcs.186148
[Indexed for MEDLINE]
Free PMC Article

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