title: The role of phosphatidylinositol 4-kinase type IIalpha in degranulation of RBL-2H3 cells.
abstract: OBJECTIVE
  We have studied the role of phosphatidylinositol 4-kinase IIalpha (PI4KIIalpha) in activation of rat basophilic leukemia (RBL-2H3) cells.
  
  
  METHODS
  Antigen-mediated intracellular Ca(2+) concentration ([Ca(2+)](i)) increase and beta-hexosaminidase secretion were measured using RBL-2H3 cells stably expressing PI4KIIalpha-yellow fluorescent protein (YFP) or its kinase-deficient mutant PI4KIIalpha (K151A)-YFP.
  
  
  RESULTS
  Neither PI4KIIalpha-YFP nor PI4KIIalpha (K151A)-YFP were distributed on the plasma membranes but on the exocytotic vesicles. The RBL-2H3 cells stably expressing PI4KIIalpha-YFP showed significantly enhanced beta-hexosaminidase secretion but not an increase in [Ca(2+)](i) after antigen stimulation. The cells with PI4KIIalpha (K151A)-YFP showed no change in the [Ca(2+)](i) increase nor degranulation. The promotion of secretion by PI4KIIalpha-YFP was not observed using co-stimulation with Ca(2+) ionophore and the protein kinase C activator, phorbol myristate acetate.
  
  
  CONCLUSIONS
  These results suggest that PI4KIIalpha plays a role in the exocytotic process downstream of Ca(2+) signaling in antigen-mediated mast cell activation.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishihara
authors.forename: T
authors.initials: T
authors.lastname: Furuno
authors.forename: M
authors.initials: M
authors.lastname: Nakanishi
mesh_terms: D000818:Animals; D000941:Antigens; D020013:Calcium Signaling / Q000502:physiology*; D015550:Cell Degranulation / Q000502:physiology*; D045744:Cell Line, Tumor; D003594:Cytoplasmic Granules / Q000502:physiology; D005089:Exocytosis / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D015471:Leukemia, Basophilic, Acute / Q000473:pathology* / Q000503:physiopathology*; D008407:Mast Cells / Q000473:pathology / Q000502:physiology; D015778:Minor Histocompatibility Antigens; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017455:Receptors, IgE / Q000502:physiology
chemical_list: D000941:Antigens; D015778:Minor Histocompatibility Antigens; D012333:RNA, Messenger; D017455:Receptors, IgE; D017853:Phosphotransferases (Alcohol Group Acceptor); C402182:phosphatidylinositol phosphate 4-kinase