@article{1910, abstract = {angerhans cells (LCs) are a unique subset of dendritic cells (DCs) that express epithelial adhesion molecules, allowing them to form contacts with epithelial cells and reside in epidermal/epithelial tissues. The dynamic regulation of epithelial adhesion plays a decisive role in the life cycle of LCs. It controls whether LCs remain immature and sessile within the epidermis or mature and egress to initiate immune responses. So far, the molecular machinery regulating epithelial adhesion molecules during LC maturation remains elusive. Here, we generated pure populations of immature human LCs in vitro to systematically probe for gene-expression changes during LC maturation. LCs down-regulate a set of epithelial genes including E-cadherin, while they upregulate the mesenchymal marker N-cadherin known to facilitate cell migration. In addition, N-cadherin is constitutively expressed by monocyte-derived DCs known to exhibit characteristics of both inflammatory-type and interstitial/dermal DCs. Moreover, the transcription factors ZEB1 and ZEB2 (ZEB is zinc-finger E-box-binding homeobox) are upregulated in migratory LCs. ZEB1 and ZEB2 have been shown to induce epithelial-to-mesenchymal transition (EMT) and invasive behavior in cancer cells undergoing metastasis. Our results provide the first hint that the molecular EMT machinery might facilitate LC mobilization. Moreover, our study suggests that N-cadherin plays a role during DC migration.}, author = {Konradi, Sabine and Yasmin, Nighat and Haslwanter, Denise and Weber, Michele and Gesslbauer, Bernd and Sixt, Michael K and Strobl, Herbert}, journal = {European Journal of Immunology}, number = {2}, pages = {553 -- 560}, publisher = {Wiley-Blackwell}, title = {{Langerhans cell maturation is accompanied by induction of N-cadherin and the transcriptional regulators of epithelial-mesenchymal transition ZEB1/2}}, doi = {10.1002/eji.201343681}, volume = {44}, year = {2014}, } @article{2839, abstract = {Directional guidance of cells via gradients of chemokines is considered crucial for embryonic development, cancer dissemination, and immune responses. Nevertheless, the concept still lacks direct experimental confirmation in vivo. Here, we identify endogenous gradients of the chemokine CCL21 within mouse skin and show that they guide dendritic cells toward lymphatic vessels. Quantitative imaging reveals depots of CCL21 within lymphatic endothelial cells and steeply decaying gradients within the perilymphatic interstitium. These gradients match the migratory patterns of the dendritic cells, which directionally approach vessels from a distance of up to 90-micrometers. Interstitial CCL21 is immobilized to heparan sulfates, and its experimental delocalization or swamping the endogenous gradients abolishes directed migration. These findings functionally establish the concept of haptotaxis, directed migration along immobilized gradients, in tissues.}, author = {Weber, Michele and Hauschild, Robert and Schwarz, Jan and Moussion, Christine and De Vries, Ingrid and Legler, Daniel and Luther, Sanjiv and Bollenbach, Mark Tobias and Sixt, Michael K}, journal = {Science}, number = {6117}, pages = {328 -- 332}, publisher = {American Association for the Advancement of Science}, title = {{Interstitial dendritic cell guidance by haptotactic chemokine gradients}}, doi = {10.1126/science.1228456}, volume = {339}, year = {2013}, } @article{522, abstract = {Podoplanin, a mucin-like plasma membrane protein, is expressed by lymphatic endothelial cells and responsible for separation of blood and lymphatic circulation through activation of platelets. Here we show that podoplanin is also expressed by thymic fibroblastic reticular cells (tFRC), a novel thymic medulla stroma cell type associated with thymic conduits, and involved in development of natural regulatory T cells (nTreg). Young mice deficient in podoplanin lack nTreg owing to retardation of CD4+CD25+ thymocytes in the cortex and missing differentiation of Foxp3+ thymocytes in the medulla. This might be due to CCL21 that delocalizes upon deletion of the CCL21-binding podoplanin from medullar tFRC to cortex areas. The animals do not remain devoid of nTreg but generate them delayed within the first month resulting in Th2-biased hypergammaglobulinemia but not in the death-causing autoimmune phenotype of Foxp3-deficient Scurfy mice.}, author = {Fuertbauer, Elke and Zaujec, Jan and Uhrin, Pavel and Raab, Ingrid and Weber, Michele and Schachner, Helga and Bauer, Miroslav and Schütz, Gerhard and Binder, Bernd and Sixt, Michael K and Kerjaschki, Dontscho and Stockinger, Hannes}, journal = {Immunology Letters}, number = {1-2}, pages = {31 -- 41}, publisher = {Elsevier}, title = {{Thymic medullar conduits-associated podoplanin promotes natural regulatory T cells}}, doi = {10.1016/j.imlet.2013.07.007}, volume = {154}, year = {2013}, } @inbook{10900, abstract = {Leukocyte migration through the interstitial space is crucial for the maintenance of tolerance and immunity. The main cues for leukocyte trafficking are chemokines thought to directionally guide these cells towards their targets. However, model systems that facilitate quantification of chemokine-guided leukocyte migration in vivo are uncommon. Here we describe an ex vivo crawl-in assay using explanted mouse ears that allows the visualization of chemokine-dependent dendritic cell (DC) motility in the dermal interstitium in real time. We present methods for the preparation of mouse ear sheets and their use in multidimensional confocal imaging experiments to monitor and analyze the directional migration of fluorescently labelled DCs through the dermis and into afferent lymphatic vessels. The assay provides a more physiological approach to study leukocyte migration than in vitro three-dimensional (3D) or 2-dimensional (2D) migration assays such as collagen gels and transwell assays.}, author = {Weber, Michele and Sixt, Michael K}, booktitle = {Chemokines}, editor = {Cardona, Astrid and Ubogu, Eroboghene}, isbn = {9781627034258}, issn = {1940-6029}, pages = {215--226}, publisher = {Humana Press}, title = {{Live Cell Imaging of Chemotactic Dendritic Cell Migration in Explanted Mouse Ear Preparations}}, doi = {10.1007/978-1-62703-426-5_14}, volume = {1013}, year = {2013}, } @article{3167, author = {Weber, Michele}, journal = {Science}, number = {6077}, pages = {32--34}, publisher = {American Association for the Advancement of Science}, title = {{NextGen speaks 13 }}, doi = {10.1126/science.336.6077.32}, volume = {336}, year = {2012}, } @article{3960, abstract = {When lymphocytes follow chemotactic cues, they can adopt different migratory modes depending on the geometry and molecular composition of their extracellular environment. In this issue of The EMBO Journal, Klemke et al (2010) describe a novel Ras-dependent chemokine receptor signalling pathway that leads to activation of cofilin, which in turn amplifies actin turnover. This signalling module is exclusively required for lymphocyte migration in three-dimensional (3D) environments, but not for locomotion on two-dimensional (2D) surfaces.}, author = {Michele Weber and Michael Sixt}, journal = {EMBO Journal}, number = {17}, pages = {2861 -- 2863}, publisher = {Wiley-Blackwell}, title = {{MEK signalling tunes actin treadmilling for interstitial lymphocyte migration}}, doi = {10.1038/emboj.2010.183}, volume = {29}, year = {2010}, } @article{3954, abstract = {The leading front of a cell can either protrude as an actin-free membrane bleb that is inflated by actomyosin-driven contractile forces, or as an actin-rich pseudopodium, a site where polymerizing actin filaments push out the membrane. Pushing filaments can only cause the membrane to protrude if the expanding actin network experiences a retrograde counter-force, which is usually provided by transmembrane receptors of the integrin family. Here we show that chemotactic dendritic cells mechanically adapt to the adhesive properties of their substrate by switching between integrin-mediated and integrin-independent locomotion. We found that on engaging the integrin-actin clutch, actin polymerization was entirely turned into protrusion, whereas on disengagement actin underwent slippage and retrograde flow. Remarkably, accelerated retrograde flow was balanced by an increased actin polymerization rate; therefore, cell shape and protrusion velocity remained constant on alternating substrates. Due to this adaptive response in polymerization dynamics, tracks of adhesive substrate did not dictate the path of the cells. Instead, directional guidance was exclusively provided by a soluble gradient of chemoattractant, which endowed these 'amoeboid' cells with extraordinary flexibility, enabling them to traverse almost every type of tissue.}, author = {Renkawitz, Jörg and Schumann, Kathrin and Weber, Michele and Lämmermann, Tim and Pflicke, Holger and Piel, Matthieu and Polleux, Julien and Spatz, Joachim and Sixt, Michael K}, journal = {Nature Cell Biology}, number = {12}, pages = {1438 -- 1443}, publisher = {Nature Publishing Group}, title = {{Adaptive force transmission in amoeboid cell migration}}, doi = {10.1038/ncb1992}, volume = {11}, year = {2009}, }