title: Requirement for a complex of Wiskott-Aldrich syndrome protein (WASP) with WASP interacting protein in podosome formation in macrophages.
abstract: Chemotactic migration of macrophages is critical for the recruitment of leukocytes to inflamed tissues. Macrophages use a specialized adhesive structure called a podosome to migrate. Podosome formation requires the Wiskott-Aldrich syndrome protein (WASP), which is a product of the gene defective in an X-linked inherited immunodeficiency disorder, the Wiskott-Aldrich syndrome. Macrophages from WASP-deficient Wiskott-Aldrich syndrome patients lack podosomes, resulting in defective chemotactic migration. However, the molecular basis for podosome formation is not fully understood. I have shown that the WASP interacting protein (WIP), a binding partner of WASP, plays an important role in podosome formation in macrophages. I showed that WASP bound WIP to form a complex at podosomes and that the knockdown of WIP impairs podosome formation. When WASP binding to WIP was blocked, podosome formation was also impaired. When WASP expression was reduced by small interfering RNA transfection, the amount of the complex of WASP with WIP decreased, resulting in reduced podosome formation. Podosomes were restored by reconstitution of the WASP-WIP complex in WASP knockdown cells. These results indicate that the WASP-WIP complex is required for podosome formation in macrophages. When podosome formation was reduced by blocking WASP binding to WIP, transendothelial migration of macrophages, the most crucial process in macrophage trafficking, was impaired. These results suggest that a complex of WASP with WIP plays a critical role in podosome formation, thereby mediating efficient transendothelial migration of macrophages.
authors.affiliation: Infectious and Inflammatory Disease Center, Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA. stsuboi@burnham.org
authors.forename: Shigeru
authors.initials: S
authors.lastname: Tsuboi
mesh_terms: D002352:Carrier Proteins / Q000276:immunology*; D002460:Cell Line; D002633:Chemotaxis / Q000235:genetics / Q000276:immunology*; D003598:Cytoskeletal Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D046912:Multiprotein Complexes / Q000235:genetics / Q000276:immunology; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D011554:Pseudopodia / Q000235:genetics / Q000276:immunology; D014923:Wiskott-Aldrich Syndrome / Q000276:immunology / Q000473:pathology; D051316:Wiskott-Aldrich Syndrome Protein / Q000172:deficiency / Q000276:immunology*
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; C495767:WAS protein, human; C109903:WIPF1 protein, human; D051316:Wiskott-Aldrich Syndrome Protein