title: Orai/CRACM1 and KCa3.1 ion channels interact in the human lung mast cell plasma membrane.
abstract: BACKGROUND
  Orai/CRACM1 ion channels provide the major Ca(2+) influx pathway for FcεRI-dependent human lung mast cell (HLMC) mediator release. The Ca(2+)-activated K(+) channel KCa3.1 modulates Ca(2+) influx and the secretory response through hyperpolarisation of the plasma membrane. We hypothesised that there is a close functional and spatiotemporal interaction between these Ca(2+)- and K(+)-selective channels.
  
  
  RESULTS
  Activation of FcεRI-dependent HLMC KCa3.1 currents was dependent on the presence of extracellular Ca(2+), and attenuated in the presence of the selective Orai blocker GSK-7975A. Currents elicited by the KCa3.1 opener 1-EBIO were also attenuated by GSK-7975A. The Orai1 E106Q dominant-negative mutant ablated 1-EBIO and FcεRI-dependent KCa3.1 currents in HLMCs. Orai1 but not Orai2 was shown to co-immunoprecipitate with KCa3.1 when overexpressed in HEK293 cells, and Orai1 and KCa3.1 were seen to co-localise in the HEK293 plasma membrane using confocal microscopy.
  
  
  CONCLUSIONS
  KCa3.1 activation in HLMCs is highly dependent on Ca(2+) influx through Orai1 channels, mediated via a close spatiotemporal interaction between the two channels.
authors.affiliation: Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, UK.
authors.forename: S Mark
authors.initials: SM
authors.lastname: Duffy
authors.affiliation: Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Ashmole
authors.affiliation: Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, UK.
authors.forename: Dawn T
authors.initials: DT
authors.lastname: Smallwood
authors.affiliation: Department of Biochemistry, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester, LE1 9HN, UK.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Leyland
authors.affiliation: Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, UK. pb46@le.ac.uk.|Department of Respiratory Medicine, Glenfield Hospital, Groby Rd, Leicester, LE3 9QP, UK. pb46@le.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Bradding
mesh_terms: D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000032:analysis / Q000378:metabolism*; D008168:Lung / Q000166:cytology; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D000071740:ORAI1 Protein; D017354:Point Mutation; D060066:Protein Interaction Maps
chemical_list: D015220:Calcium Channels; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496923:KCNN4 protein, human; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; D002118:Calcium