title: Regulation of Na⁺/H⁺ Exchanger in Dendritic Cells by Akt1.
abstract: OBJECTIVE
  Dendritic cells (DCs), antigen-presenting cells critically important for primary immune response and establishment of immunological memory, are activated by bacterial lipopolysaccharides (LPS) resulting in stimulation of Na(+)/H(+) exchanger, ROS formation and migration. The effects are dependent on phosphoinositide 3 (PI3) kinase and paralleled by Akt phosphorylation. The present study explored the contribution of the Akt isoform Akt1.
  
  
  METHODS
  Cytosolic pH (pH(i)) (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein [BCECF] fluorescence), Na(+)/H(+) exchanger activity (Na(+) dependent realkalinization after an ammonium pulse), cell volume (forward scatter in FACS analysis), and ROS production (2',7'-dichlorodihydrofluorescein diacetate [DCFDA] fluorescence) were determined in DCs isolated from bone marrow of mice lacking functional Akt1/PKBα (akt1(-/-)) and their wild type littermates (akt1(+/+)).
  
  
  RESULTS
  Forward scatter was lower in akt1(-/-) than in akt1(+/+) DCs, whereas pH(i), Na(+)/H(+) exchanger activity and ROS formation were less in untreated akt1(-/-) and akt1(+/+) DCs. Exposure of DCs to LPS was followed by increase of forward scatter and ROS formation to a similar extent in akt1(-/-) and in akt1(+/+) DCs. A 4 hours treatment with either LPS (1µg/ml) or tert-butylhydroperoxide (tBOOH, 5 µM) significantly stimulated Na(+)/H(+) exchanger activity in both genotypes, effects, however, significantly blunted in akt1(-/-) DCs.
  
  
  CONCLUSIONS
  The present observations demonstrate that Akt1 is required for the full stimulation of Na(+)/H(+) exchanger activity by LPS or oxidative stress in dendritic cells.
authors.affiliation: Department of Physiology, University of Tübingen, Germany.
authors.forename: Yuetao
authors.initials: Y
authors.lastname: Zhou
authors.forename: Venkanna
authors.initials: V
authors.lastname: Pasham
authors.forename: Soumya
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Anand
authors.initials: A
authors.lastname: Rotte
authors.forename: Wenting
authors.initials: W
authors.lastname: Yang
authors.forename: Madhuri
authors.initials: M
authors.lastname: Bhandaru
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Singh
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005786:Gene Expression Regulation; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D061251:Primary Cell Culture; D051057:Proto-Oncogene Proteins c-akt / Q000172:deficiency / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D017923:Sodium-Hydrogen Exchangers; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D020122:tert-Butylhydroperoxide; D019869:Phosphatidylinositol 3-Kinases; C514862:Akt1 protein, mouse; D051057:Proto-Oncogene Proteins c-akt