Dynamic interactions of Fc gamma receptor IIB with filamin-bound SHIP1 amplify filamentous actin-dependent negative regulation of Fc epsilon receptor I signaling.

Renaud Lesourne (1, 2) , Wolf H. Fridman (2) , Marc Daëron (1, 2)

1 Allergologie Moléculaire et Cellulaire
2 Laboratoire d'Immunologie Cellulaire et Clinique

The engagement of high affinity receptors for IgE (FcepsilonRI) generates both positive and negative signals whose integration determines the intensity of mast cell responses. FcepsilonRI-positive signals are also negatively regulated by low affinity receptors for IgG (FcgammaRIIB). Although the constitutive negative regulation of FcepsilonRI signaling was shown to depend on the submembranous F-actin skeleton, the role of this compartment in FcgammaRIIB-dependent inhibition is unknown. We show in this study that the F-actin skeleton is essential for FcgammaRIIB-dependent negative regulation. It contains SHIP1, the phosphatase responsible for inhibition, which is constitutively associated with the actin-binding protein, filamin-1. After coaggregation, FcgammaRIIB and FcepsilonRI rapidly interact with the F-actin skeleton and engage SHIP1 and filamin-1. Later, filamin-1 and F-actin dissociate from FcR complexes, whereas SHIP1 remains associated with FcgammaRIIB. Based on these results, we propose a dynamic model in which the submembranous F-actin skeleton forms an inhibitory compartment where filamin-1 functions as a donor of SHIP1 for FcgammaRIIB, which concentrate this phosphatase in the vicinity of FcepsilonRI and thereby extinguish activation signals.

Domains: Life Sciences [q-bio]; Immunology; Allergology

Renaud Lesourne, Wolf H. Fridman, Marc Daëron. Dynamic interactions of Fc gamma receptor IIB with filamin-bound SHIP1 amplify filamentous actin-dependent negative regulation of Fc epsilon receptor I signaling.. Journal of Immunology, 2005, 174 (3), pp.1365-73. ⟨10.4049/jimmunol.174.3.1365⟩. ⟨pasteur-00270058⟩