Btk-dependent Rac activation and actin rearrangement following FcepsilonRI aggregation promotes enhanced chemotactic responses of mast cells.
Mast cells infiltrate the sites of inflammation associated with chronic atopic disease and during helminth and bacterial infection. This process requires receptor-mediated cell chemotaxis across a concentration gradient of their chemotactic ligands. In vivo, mast cells are likely to be exposed to several such agents, which can cooperate in a synergistic manner to regulate mast cell homing. Here, we report that chemotaxis of mouse bone-marrow-derived mast cells (BMMCs) in response to the chemoattractants stem-cell factor (SCF) and prostaglandin (PG)E(2), is substantially enhanced following antigen-dependent ligation of the high-affinity receptor for IgE (FcεRI). These responses were associated with enhanced activation of phosphoinositide 3-kinase (PI3K), and downstream activation of the tyrosine protein kinase Btk, with subsequent enhanced phospholipase (PL)Cγ-mediated Ca(2+) mobilization, Rac activation and F-actin rearrangement. Antigen-induced chemotaxis, and the ability of antigen to amplify responses mediated by SCF, adenosine and PGE(2) were suppressed following inhibition of PI3K, and were impaired in BMMCs derived from Btk(-/-) mice. There were corresponding decreases in the PLCγ-mediated Ca(2+) signal, Rac activation and F-actin rearrangement, which, as they are essential for BMMC chemotaxis, accounts for the impaired migration of Btk-deficient cells. Taken together, these data demonstrate that, by regulating signaling pathways that control F-actin rearrangement, Btk is crucial for the ability of antigen to amplify mast-cell chemotactic responses.
Kuehn
Hye Sun
HS
Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 10 Center Drive MSC 1881, Bethesda, MD 20892-1881, USA.
Rådinger
Madeleine
M
Brown
Jared M
JM
Ali
Khaled
K
Vanhaesebroeck
Bart
B
Beaven
Michael A
MA
Metcalfe
Dean D
DD
Gilfillan
Alasdair M
AM
D000199:Actins / Q000378:metabolism; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects* / Q000235:genetics; D015232:Dinoprostone; D005434:Flow Cytometry; D015151:Immunoblotting; D008407:Mast Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008856:Microscopy, Fluorescence; D051966:Phospholipase C gamma / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D019089:Stem Cell Factor / Q000494:pharmacology; D020744:rac GTP-Binding Proteins
D000199:Actins; D019089:Stem Cell Factor; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; D051966:Phospholipase C gamma; D020744:rac GTP-Binding Proteins; D015232:Dinoprostone; D002118:Calcium