WIP peptide stabilizes WASP in cells from Wiskott-Aldrich syndrome (WAS) patients with mutations in the WIP-binding domain (33.16)

Abstract

Abstract WAS is an X-linked immunodeficiency characterized by eczema, thrombocytopenia and recurrent infections. WAS-protein (WASP) links cell surface signals to the actin cytoskeleton. WASP is important in T cells for IL-2 production, proliferation, and migration. The WAS-interacting protein (WIP) stabilizes WASP. WASP level is severely reduced in T cells of WIP KO mice. The majority of missense mutations in WAS patients are in the WIP binding domain (WBD) of WASP and interfere with WIP binding, resulting in low WASP levels. We identified a 35 a.a. fragment of WIP (termed nWIP), which when fused to the C-terminal of EGFP (EGFP-nWIP), interacts with WASP in Jurkat cells. When introduced into WIP KO T cells, EGFP-nWIP increased the level of WASP to normal, as determined by FACS analysis. EBV-transformed B cell lines from WAS patients with mutations in the WBD of WASP expressed low levels of WASP, but had normal mRNA levels. Introduction of EGFP-nWIP into these lines resulted in increased levels of WASP, up to normal. Two cell lines from patients with WAS mutations outside the WIP-binding domain did not show an increase of WASP after introduction of EGFP-nWIP. Our results demonstrate that nWIP stabilizes WASP and ameliorates WASP levels in B cells from WAS patients with missesense mutations in the WBD of WASP. We will determine if nWIP will correct the functional defects in cells from these patients. (Supported by USPHS grant HL059561 and the PERKIN fund.)