title: High CO2 Leads to Na,K-ATPase Endocytosis via c-Jun Amino-Terminal Kinase-Induced LMO7b Phosphorylation.
abstract: The c-Jun amino-terminal kinase (JNK) plays a role in inflammation, proliferation, apoptosis, and cell adhesion and cell migration by phosphorylating paxillin and β-catenin. JNK phosphorylation downstream of AMP-activated protein kinase (AMPK) activation is required for high CO2 (hypercapnia)-induced Na,K-ATPase endocytosis in alveolar epithelial cells. Here, we provide evidence that during hypercapnia, JNK promotes the phosphorylation of LMO7b, a scaffolding protein, in vitro and in intact cells. LMO7b phosphorylation was blocked by exposing the cells to the JNK inhibitor SP600125 and by infecting cells with dominant-negative JNK or AMPK adenovirus. The knockdown of the endogenous LMO7b or overexpression of mutated LMO7b with alanine substitutions of five potential JNK phosphorylation sites (LMO7b-5SA) or only Ser-1295 rescued both LMO7b phosphorylation and the hypercapnia-induced Na,K-ATPase endocytosis. Moreover, high CO2 promoted the colocalization and interaction of LMO7b and the Na,K-ATPase α1 subunit at the plasma membrane, which were prevented by SP600125 or by transfecting cells with LMO7b-5SA. Collectively, our data suggest that hypercapnia leads to JNK-induced LMO7b phosphorylation at Ser-1295, which facilitates the interaction of LMO7b with Na,K-ATPase at the plasma membrane promoting the endocytosis of Na,K-ATPase in alveolar epithelial cells.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA Lauradada@northwestern.edu.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Dada
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Humberto E
authors.initials: HE
authors.lastname: Trejo Bittar
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Welch
authors.affiliation: Department of Physiology, UCLA, and Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, California, 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, Illinois, USA.
authors.forename: Nimrod
authors.initials: N
authors.lastname: Deiss-Yehiely
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Aileen M
authors.initials: AM
authors.lastname: Kelly
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Mairead R
authors.initials: MR
authors.lastname: Baker
authors.affiliation: The NPI-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Capri
authors.affiliation: The NPI-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California, USA.
authors.forename: Whitaker
authors.initials: W
authors.lastname: Cohn
authors.affiliation: The NPI-Semel Institute, Pasarow Mass Spectrometry Laboratory, UCLA, Los Angeles, California, USA.
authors.forename: Julian P
authors.initials: JP
authors.lastname: Whitelegge
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Giessen, Germany.
authors.forename: István
authors.initials: I
authors.lastname: Vadász
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA The Alexander Silberman Institute of Life Sciences, Edmond Safra Campus, The Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Yosef
authors.initials: Y
authors.lastname: Gruenbaum
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Sznajder
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002460:Cell Line; D004705:Endocytosis; D004789:Enzyme Activation; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000032:analysis / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D060066:Protein Interaction Maps; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000378:metabolism*; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; C490020:LMO7 protein, rat; D014157:Transcription Factors; D002245:Carbon Dioxide; D048031:JNK Mitogen-Activated Protein Kinases; D000254:Sodium-Potassium-Exchanging ATPase