Nck1 and Grb2 localization patterns can distinguish invadopodia from podosomes.

Invadopodia are matrix-degrading ventral cell surface structures formed in invasive carcinoma cells. Podosomes are matrix-degrading structures formed in normal cell types including macrophages, endothelial cells, and smooth muscle cells that are believed to be related to invadopodia in function. Both invadopodia and podosomes are enriched in proteins that regulate actin polymerization including proteins involved in N-WASp/WASp-dependent Arp2/3-complex activation. However, it is unclear whether invadopodia and podosomes use distinct mediators for N-WASp/WASp-dependent Arp2/3-complex activation. We investigated the localization patterns of the upstream N-WASp/WASp activators Nck1 and Grb2 in invadopodia of metastatic mammary carcinoma cells, podosomes formed in macrophages, and degradative structures formed in Src-transformed fibroblasts and PMA-stimulated endothelial cells. We provide evidence that Nck1 specifically localizes to invadopodia, but not to podosomes formed in macrophages or degradative structures formed in Src-transformed fibroblasts and PMA-stimulated endothelial cells. In contrast, Grb2 specifically localizes to degradative structures formed in Src-transformed fibroblasts and PMA-stimulated endothelial cells, but not invadopodia or podosomes formed in macrophages. These findings suggest that distinct upstream activators are responsible for N-WASp/WASp activation in invadopodia and podosomes, and that all these ventral cell surface degradative structures have distinguishing molecular as well as structural characteristics. These patterns of Nck1 and Grb2 localization, identified in our study, can be used to sub-classify ventral cell surface degradative structures.

Oser M ，Dovas A ，Cox D ，Condeelis J ... -  《-》

Molecular mechanisms of invadopodium formation: the role of the N-WASP-Arp2/3 complex pathway and cofilin.

Yamaguchi H ，Lorenz M ，Kempiak S ，Sarmiento C ，Coniglio S ，Symons M ，Segall J ，Eddy R ，Miki H ，Takenawa T ，Condeelis J ... -  《-》

Specific tyrosine phosphorylation sites on cortactin regulate Nck1-dependent actin polymerization in invadopodia.

Oser M ，Mader CC ，Gil-Henn H ，Magalhaes M ，Bravo-Cordero JJ ，Koleske AJ ，Condeelis J ... -  《-》

The non-redundant role of N-WASP in podosome-mediated matrix degradation in macrophages.

Wiskott-Aldrich Syndrome Protein (WASP) is a hematopoietic cell-specific regulator of Arp2/3-dependent actin polymerization. Despite the presence of the highly homologous N-WASP (neural-WASP), macrophages from WAS patients are devoid of podosomes, adhesion structures in cells of the monocytic lineage capable of matrix degradation via matrix metalloproteases (MMPs), suggesting that WASP and N-WASP play unique roles in macrophages. To determine whether N-WASP also plays a unique role in macrophage function, N-WASP expression was reduced using silencing RNA in a sub-line of RAW 264.7 macrophages (RAW/LR5). Similar to reduction in WASP levels, cells with reduced N-WASP levels were rounder and less polarized. Interestingly, podosomes still formed when N-WASP was reduced but they were unable to perform matrix degradation. This defect was rescued by re-expression of N-WASP, but not by over-expression of WASP, indicating that these proteins play distinct roles in podosome function. Additionally, reducing N-WASP levels mistargets the metalloprotease MT1-MMP and it no longer localizes to podosomes. However, N-WASP was only found to co-localize with MT1-MMP positive vesicles at podosomes, suggesting that N-WASP may play a role on the targeting or fusion of MMP-containing vesicles to podosomes in macrophage-like cells.

Nusblat LM ，Dovas A ，Cox D 《-》

Essential role of neural Wiskott-Aldrich syndrome protein in podosome formation and degradation of extracellular matrix in src-transformed fibroblasts.

Mizutani K ，Miki H ，He H ，Maruta H ，Takenawa T ... -  《CANCER RESEARCH》