Mast cells are key participants in allergic diseases via activation of high-affinity IgE receptors (FcεRI) resulting in release of proinflammatory mediators. The biochemical pathways linking IgE activation to calcium influx and cytoskeletal changes required for intracellular granule release are incompletely understood. We demonstrate, genetically, that Pak1 is required for this process. In a passive cutaneous anaphylaxis experiment, W sh/W sh mast cell-deficient mice locally reconstituted with Pak1 -/- bone marrow-derived mast cells (BMMCs) experienced strikingly decreased allergen-induced vascular permeability compared with controls. Consistent with the in vivo phenotype, Pak1 -/- BMMCs exhibited a reduction in FcεRI-induced degranulation. Further, Pak1 -/- BMMCs demonstrated diminished calcium mobilization and altered depolymerization of cortical filamentous actin (F-actin) in response to FcεRI stimulation. These data implicate Pak1 as an essential molecular target for modulating acute mast cell responses that contribute to allergic diseases.
ASJC Scopus subject areas
- Cell Biology