Disease-associated missense mutations in the EVH1 domain disrupt intrinsic WASp function causing dysregulated actin dynamics and impaired dendritic cell migration.

Wiskott Aldrich syndrome (WAS), an X-linked immunodeficiency, results from loss-of-function mutations in the human hematopoietic cytoskeletal regulator gene WAS. Many missense mutations in the Ena Vasp homology1 (EVH1) domain preserve low-level WAS protein (WASp) expression and confer a milder clinical phenotype. Although disrupted binding to WASp-interacting protein (WIP) leads to enhanced WASp degradation in vivo, the intrinsic function of EVH1-mutated WASp is poorly understood.

Lentivectors are efficient tools to manipulate the dendritic cell cytoskeleton.

Dendritic cells (DC) are key cells of the innate immune system required to prime adaptive immunity. Central DC functions including antigen uptake and presentation and DC migration are critically dependent on dynamic cytoskeletal reorganisation, the regulation of which remains poorly understood. Cytoskeletal studies are complicated by the fact that DC cytoarchitecture is altered considerably by maturation stimuli, including many tools employed for biological manipulation.

A congenital activating mutant of WASp causes altered plasma membrane topography and adhesion under flow in lymphocytes.

Leukocytes rely on dynamic actin-dependent changes in cell shape to pass through blood vessels, which is fundamental to immune surveillance. Wiskott-Aldrich Syndrome protein (WASp) is a hematopoietic cell-restricted cytoskeletal regulator important for modulating cell shape through Arp2/3-mediated actin polymerization. A recently identified WASp(I294T) mutation was shown to render WASp constitutively active in vivo, causing increased filamentous (F)-actin polymerization, high podosome turnover in macrophages, and myelodysplasia.

Phosphorylation of WASp is a key regulator of activity and stability in vivo.

The Wiskott-Aldrich syndrome protein (WASp) is a key cytoskeletal regulator in hematopoietic cells. Covalent modification of a conserved tyrosine by phosphorylation has emerged as an important potential determinant of activity, although the physiological significance remains uncertain. In a murine knockin model, mutation resulting in inability to phosphorylate Y293 (Y293F) mimicked many features of complete WASp-deficiency.