Dynamique des complexes de signalisation qui contrôlent l'activation des mastocytes

Mast cell activation is negatively regulated by several mechanisms which use the inositol phosphatase SHIP1 as an effector molecule. This intracellular enzyme dephosphorylates membrane phospholipids which play critical roles in intracellular signaling generated by high-affinity IgE receptors. It determines a sensitivity threshold to extracellular stimuli in resting mast cells; it adjusts the magnitude of allergen-induced responses to the extent of engagement of IgE receptors; it shuts off these responses when allergen-IgG antibody immune complexes coengage inhibitory and activating receptors on the mast cell membrane. The involvement of SHIP1 under these conditions depends on the dynamics of intracellular signaling complexes that build-up underneath engaged receptors and, especially, on their association with the actin cytoskeleton in which are generated and amplified the negative signals which antagonize with IgE receptor-dependent positive signals.