title: Novel role for Na,K-ATPase in phosphatidylinositol 3-kinase signaling and suppression of cell motility.
abstract: The Na,K-ATPase, consisting of alpha- and beta-subunits, regulates intracellular ion homeostasis. Recent studies have demonstrated that Na,K-ATPase also regulates epithelial cell tight junction structure and functions. Consistent with an important role in the regulation of epithelial cell structure, both Na,K-ATPase enzyme activity and subunit levels are altered in carcinoma. Previously, we have shown that repletion of Na,K-ATPase beta1-subunit (Na,K-beta) in highly motile Moloney sarcoma virus-transformed Madin-Darby canine kidney (MSV-MDCK) cells suppressed their motility. However, until now, the mechanism by which Na,K-beta reduces cell motility remained elusive. Here, we demonstrate that Na,K-beta localizes to lamellipodia and suppresses cell motility by a novel signaling mechanism involving a cross-talk between Na,K-ATPase alpha1-subunit (Na,K-alpha) and Na,K-beta with proteins involved in phosphatidylinositol 3-kinase (PI3-kinase) signaling pathway. We show that Na,K-alpha associates with the regulatory subunit of PI3-kinase and Na,K-beta binds to annexin II. These molecular interactions locally activate PI3-kinase at the lamellipodia and suppress cell motility in MSV-MDCK cells, independent of Na,K-ATPase ion transport activity. Thus, these results demonstrate a new role for Na,K-ATPase in regulating carcinoma cell motility.
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
authors.forename: Sonali P
authors.initials: SP
authors.lastname: Barwe
authors.forename: Gopalakrishnapillai
authors.initials: G
authors.lastname: Anilkumar
authors.forename: Sun Y
authors.initials: SY
authors.lastname: Moon
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Julian P
authors.initials: JP
authors.lastname: Whitelegge
authors.forename: Sigrid A
authors.initials: SA
authors.lastname: Rajasekaran
authors.forename: Ayyappan K
authors.initials: AK
authors.lastname: Rajasekaran
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D017306:Annexin A2 / Q000737:chemistry / Q000235:genetics; D002460:Cell Line; D002465:Cell Movement; D002853:Chromatography, Liquid; D002867:Chromones / Q000494:pharmacology; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology; D005982:Glutathione Transferase / Q000378:metabolism; D015151:Immunoblotting; D047468:Immunoprecipitation; D007477:Ions; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000378:metabolism; D010590:Phalloidine / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000502:physiology*; D019108:Tight Junctions; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; D017306:Annexin A2; D002867:Chromones; D005982:Glutathione Transferase; D007477:Ions; D009025:Morpholines; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D010590:Phalloidine; D019869:Phosphatidylinositol 3-Kinases; D011993:Recombinant Fusion Proteins; D000254:Sodium-Potassium-Exchanging ATPase; D020830:rac1 GTP-Binding Protein; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one