Directional migration of neural crest cells in vivo is regulated by Syndecan-4/Rac1 and non-canonical Wnt signaling/RhoA

Helen K. Matthews, Lorena Marchant, Carlos Carmona-Fontaine, Sei Kuriyama, Juan Larraín, Mark R. Holt, Maddy Parsons and Roberto Mayor

Development 135, 1771-1780 (2008 ) doi: 10.1242/dev.017350

Directed cell migration is crucial for development, but most of our current knowledge is derived from in vitro studies. We analyzed how neural crest (NC) cells migrate in the direction of their target during embryonic development. We show that the proteoglycan Syndecan-4 (Syn4) is expressed in the migrating neural crest of Xenopus and zebrafish embryos. Loss-of-function studies using an antisense morpholino against syn4 show that this molecule is required for NC migration, but not for NC induction. Inhibition of Syn4 does not affect the velocity of cell migration, but significantly reduces the directional migration of NC cells. Furthermore, we show that Syn4 and PCP signaling control the directional migration of NC cells by regulating the direction in which the cell protrusions are generated during migration. Finally, we perform FRET analysis of Cdc42, Rac and RhoA in vitro and in vivo after interfering with Syn4 and PCP signaling. This is the first time that FRET analysis of small GTPases has been performed in vivo. Our results show that Syn4 inhibits Rac activity, whereas PCP signaling promotes RhoA activity. In addition, we show that RhoA inhibits Rac in NC cells. We present a model in which Syn4 and PCP control directional NC migration by, at least in part, regulating membrane protrusions through the regulation of small GTPase activities.

The WAVE/SCAR complex promotes polarized cell movements and actin enrichment in epithelia during C. elegans embryogenesis

Falshruti B. Patel, Yelena Y. Bernadskaya, Esteban Chen, Aesha Jobanputra, Zahra Pooladi, Kristy L. Freeman, Christelle Gally, William A. Mohler and Martha C. Soto

Developmental Biology Volume 324, Issue 2, 15 December 2008, Pages 297-309 doi:10.1016/j.ydbio.2008.09.023

The WAVE/SCAR complex promotes actin nucleation through the Arp2/3 complex, in response to Rac signaling. We show that loss of WVE-1/GEX-1, the only C. elegans WAVE/SCAR homolog, by genetic mutation or by RNAi, has the same phenotype as loss of GEX-2/Sra1/p140/PIR121, GEX-3/NAP1/HEM2/KETTE, or ABI-1/ABI, the three other components of the C. elegans WAVE/SCAR complex. We find that the entire WAVE/SCAR complex promotes actin-dependent events at different times and in different tissues during development. During C. elegans embryogenesis loss of CED-10/Rac1, WAVE/SCAR complex components, or Arp2/3 blocks epidermal cell migrations despite correct epidermal cell differentiation. 4D movies show that this failure occurs due to decreased membrane dynamics in specific epidermal cells. Unlike myoblasts in Drosophila, epidermal cell fusions in C. elegans can occur in the absence of WAVE/SCAR or Arp2/3. Instead we find that subcellular enrichment of F-actin in epithelial tissues requires the Rac-WAVE/SCAR-Arp2/3 pathway. Intriguingly, we find that at the same stage of development both F-actin and WAVE/SCAR proteins are enriched apically in one epithelial tissue and basolaterally in another. We propose that temporally and spatially regulated actin nucleation by the Rac-WAVE/SCAR-Arp2/3 pathway is required for epithelial cell organization and movements during morphogenesis.

Wnt/β-Catenin and Fgf Signaling Control Collective Cell Migration by Restricting Chemokine Receptor Expression

Andy Aman and Tatjana Piotrowski

Developmental Cell Volume 15, Issue 5, 11 November 2008, Pages 749-761 doi:10.1016/j.devcel.2008.10.002

Collective cell migration is a hallmark of embryonic morphogenesis and cancer metastases. However, the molecular mechanisms regulating coordinated cell migration remain poorly understood. A genetic dissection of this problem is afforded by the migrating lateral line primordium of the zebrafish. We report that interactions between Wnt/β-catenin and Fgf signaling maintain primordium polarity by differential regulation of gene expression in the leading versus the trailing zone. Wnt/β-catenin signaling in leader cells informs coordinated migration via differential regulation of the two chemokine receptors, cxcr4b and cxcr7b. These findings uncover a molecular mechanism whereby a migrating tissue maintains stable, polarized gene expression domains despite periodic loss of whole groups of cells. Our findings also bear significance for cancer biology. Although the Fgf, Wnt/β-catenin, and chemokine signaling pathways are well known to be involved in cancer progression, these studies provide in vivo evidence that these pathways are functionally linked.

Compensation mechanism in tumor cell migration : mesenchymal–amoeboid transition after blocking of pericellular proteolysis

The Journal of Cell Biology, Volume 160, Number 2, 267-277

Katarina Wolf, Irina Mazo, Harry Leung, Katharina Engelke, Ulrich H. von Andrian, Elena I. Deryugina, Alex Y. Strongin, Eva-B. Bröcker and Peter Friedl

Video 6 (6.8 MB)
Protease-independent crawling lacks structural matrix remodeling. Fiber bundling at leading and trailing edges is reduced. After detachment, intact fibers rebound to their original position. The cell tends to align in parallel to preformed fibers (contact guidance). The image size is 90 x 90 µm, and the time frame is 65 min

Intéressant.

Invasive tumor dissemination in vitro and in vivo involves the proteolytic degradation of ECM barriers. This process, however, is only incompletely attenuated by protease inhibitor–based treatment, suggesting the existence of migratory compensation strategies. In three-dimensional collagen matrices, spindle-shaped proteolytically potent HT-1080 fibrosarcoma and MDA-MB-231 carcinoma cells exhibited a constitutive mesenchymal-type movement including the coclustering of ß1 integrins and MT1–matrix metalloproteinase (MMP) at fiber bindings sites and the generation of tube-like proteolytic degradation tracks. Near-total inhibition of MMPs, serine proteases, cathepsins, and other proteases, however, induced a conversion toward spherical morphology at near undiminished migration rates. Sustained protease-independent migration resulted from a flexible amoeba-like shape change, i.e., propulsive squeezing through preexisting matrix gaps and formation of constriction rings in the absence of matrix degradation, concomitant loss of clustered ß1 integrins and MT1-MMP from fiber binding sites, and a diffuse cortical distribution of the actin cytoskeleton. Acquisition of protease-independent amoeboid dissemination was confirmed for HT-1080 cells injected into the mouse dermis monitored by intravital multiphoton microscopy. In conclusion, the transition from proteolytic mesenchymal toward nonproteolytic amoeboid movement highlights a supramolecular plasticity mechanism in cell migration and further represents a putative escape mechanism in tumor cell dissemination after abrogation of pericellular proteolysis.

Non-canonical Wnt signaling through Wnt5a/b and a novel Wnt11 gene, Wnt11b, regulates cell migration during avian gastrulation. Dev Biol (2008) vol. 320 (2) doi: 10.1016/j.ydbio.2008.05.546

Katharine M. Hardy, Robert J. Garriock, Tatiana A. Yatskievych, Susan L. D’Agostino, Parker B. Antin and Paul A. Krieg

Knowledge of the molecular mechanisms regulating cell ingression, epithelial–mesenchymal transition and migration movements during amniote gastrulation is steadily improving. In the frog and fish embryo, Wnt5 and Wnt11 ligands are expressed around the blastopore and play an important role in regulating cell movements associated with gastrulation. In the chicken embryo, although Wnt5a and Wnt5b are expressed in the primitive streak, the known Wnt11 gene is expressed in paraxial and intermediate mesoderm, and in differentiated myocardial cells, but not in the streak. Here, we identify a previously uncharacterized chicken Wnt11 gene, Wnt11b, that is orthologous to the frog Wnt11 and zebrafish Wnt11 (silberblick) genes. Chicken Wnt11b is expressed in the primitive streak in a pattern similar to chicken Wnt5a and Wnt5b. When non-canonical Wnt signaling is blocked using a Dishevelled dominant-negative protein, gastrulation movements are inhibited and cells accumulate in the primitive streak. Furthermore, disruption of non-canonical Wnt signaling by overexpression of full-length or dominant-negative Wnt11b or Wnt5a constructions abrogates normal cell migration through the primitive streak. We conclude that non-canonical Wnt signaling, mediated in part by Wnt11b, is important for regulation of gastrulation cell movements in the avian embryo.

Endothelial cell migration in stable gradients of VEGFA and FGF2: Effects on chemotaxis and chemokinesis — doi: 10.1074/jbc.M704917200 — Journal of Biological Chemistry: “Papers In Press, published online ahead of print March 17, 2008
J. Biol. Chem, 10.1074/jbc.M704917200

Irmeli Barkefors, Sébastien Le Jan, Lars Jakobsson, Eduar Hejll, Gustav Carlson, Henrik Johansson, Jonas Jarvius, Jeong Won Park, Noo Li Jeon, and Johan Kreuger

Gradients of secreted signaling proteins guide growing blood vessels during both normal and pathological angiogenesis. However, the mechanisms by which endothelial cells integrate and respond to graded distributions of chemotactic factors are still poorly understood. We have in the present study investigated endothelial cell migration in response to hill-shaped gradients of vascular endothelial growth factor A (VEGFA) and fibroblast growth factor 2 (FGF2) using a novel microfluidic chemotaxis chamber (MCC). Cell migration was scored at the level of individual cells using time-lapse microscopy. A stable gradient of VEGFA165 ranging from 0-50 ng/ml over a distance of 400 µm was shown to strongly induce chemotaxis of endothelial cells of different vascular origin. VEGFA121, unable to bind proteoglycan and neuropilin coreceptors, was also shown to induce chemotaxis in this setup. Further, a gradient of FGF2 was able to attract venular but not arterial endothelial cells, albeit less efficiently than VEGFA165. Notably, constant levels of VEGFA165, but not of FGF2, were shown to efficiently reduce chemokinesis. Systematic exploration of different gradient shapes led to the identification of a minimal gradient steepness required for efficient cell guidance. Finally, analysis of cell migration in different regions of the applied gradients showed that chemotaxis is reduced when cells reach the high end of the gradient. Our findings suggest that chemotactic growth factor gradients may instruct endothelial cells to shift toward a non-migratory phenotype when approaching the growth factor source.”