Blunted IgE-mediated activation of mast cells in mice lacking the Ca2+-activated K+ channel KCa3.1.
Mast cell stimulation by Ag is followed by the opening of Ca(2+)-activated K(+) channels, which participate in the orchestration of mast cell degranulation. The present study has been performed to explore the involvement of the Ca(2+)-activated K(+) channel K(Ca)3.1 in mast cell function. To this end mast cells have been isolated and cultured from the bone marrow (bone marrow-derived mast cells (BMMCs)) of K(Ca)3.1 knockout mice (K(Ca)3.1(-/-)) and their wild-type littermates (K(Ca)3.1(+/+)). Mast cell number as well as in vitro BMMC growth and CD117, CD34, and FcepsilonRI expression were similar in both genotypes, but regulatory cell volume decrease was impaired in K(Ca)3.1(-/-) BMMCs. Treatment of the cells with Ag, endothelin-1, or the Ca(2+) ionophore ionomycin was followed by stimulation of Ca(2+)-activated K(+) channels and cell membrane hyperpolarization in K(Ca)3.1(+/+), but not in K(Ca)3.1(-/-) BMMCs. Upon Ag stimulation, Ca(2+) entry but not Ca(2+) release from intracellular stores was markedly impaired in K(Ca)3.1(-/-) BMMCs. Similarly, Ca(2+) entry upon endothelin-1 stimulation was significantly reduced in K(Ca)3.1(-/-) cells. Ag-induced release of beta-hexosaminidase, an indicator of mast cell degranulation, was significantly smaller in K(Ca)3.1(-/-) BMMCs compared with K(Ca)3.1(+/+) BMMCs. Moreover, histamine release upon stimulation of BMMCs with endothelin-1 was reduced in K(Ca)3.1(-/-) cells. The in vivo Ag-induced decline in body temperature revealed that IgE-dependent anaphylaxis was again significantly (by approximately 50%) blunted in K(Ca)3.1(-/-) mice. In conclusion, K(Ca)3.1 is required for Ca(2+)-activated K(+) channel activity and Ca(2+)-dependent processes such as endothelin-1- or Ag-induced degranulation of mast cells, and may thus play a critical role in anaphylactic reactions.
Department of Physiology, University of Tübingen, Tübingen, Germany.
Ekaterina
E
Shumilina
Rebecca S
RS
Lam
Florian
F
Wölbing
Nicole
N
Matzner
Irina M
IM
Zemtsova
Malgorzata
M
Sobiesiak
Hasan
H
Mahmud
Ulrike
U
Sausbier
Tilo
T
Biedermann
Peter
P
Ruth
Matthias
M
Sausbier
Florian
F
Lang
D000707:Anaphylaxis / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000818:Animals; D000941:Antigens / Q000276:immunology; D001693:Biological Transport, Active / Q000276:immunology; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000502:physiology; D015550:Cell Degranulation / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D049109:Cell Proliferation; D048429:Cell Size; D002478:Cells, Cultured; D004136:Dinitrobenzenes / Q000276:immunology; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D007073:Immunoglobulin E / Q000096:biosynthesis / Q000502:physiology*; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology; D008297:Male; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
D000941:Antigens; D004136:Dinitrobenzenes; D019332:Endothelin-1; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496925:Kcnn4 protein, mouse; D007073:Immunoglobulin E; D002118:Calcium