XB-ART-50105
Development
2015 Feb 01;1423:486-96. doi: 10.1242/dev.108266.
Show Gene links
Show Anatomy links
Regulation of ECM degradation and axon guidance by growth cone invadosomes.
Santiago-Medina M
,
Gregus KA
,
Nichol RH
,
O'Toole SM
,
Gomez TM
.
???displayArticle.abstract???
Invadopodia and podosomes, collectively referred to as invadosomes, are F-actin-rich basal protrusions of cells that provide sites of attachment to and degradation of the extracellular matrix. Invadosomes promote the invasion of cells, ranging from metastatic cancer cells to immune cells, into tissue. Here, we show that neuronal growth cones form protrusions that share molecular, structural and functional characteristics of invadosomes. Growth cones from all neuron types and species examined, including a variety of human neurons, form invadosomes both in vitro and in vivo. Growth cone invadosomes contain dynamic F-actin and several actin regulatory proteins, as well as Tks5 and matrix metalloproteinases, which locally degrade the matrix. When viewed using three-dimensional super-resolution microscopy, F-actin foci often extended together with microtubules within orthogonal protrusions emanating from the growth cone central domain. Finally, inhibiting the function of Tks5 both reduced matrix degradation in vitro and disrupted motoneuron axons from exiting the spinal cord and extending into the periphery. Taken together, our results suggest that growth cones use invadosomes to target protease activity during axon guidance through tissues.
???displayArticle.pubmedLink??? 25564649
???displayArticle.pmcLink??? PMC4302990
???displayArticle.link??? Development
???displayArticle.grants??? [+]
NS088477 NINDS NIH HHS , NS41564 NINDS NIH HHS , R01 NS041564 NINDS NIH HHS , T32 GM007507 NIGMS NIH HHS , R56 NS041564 NINDS NIH HHS , R21 NS088477 NINDS NIH HHS
Species referenced: Xenopus laevis
Genes referenced: actb actl6a actn1 actr3 adam17 b3gat1l cttn enah fn1 itgb1 mmp14 mmp2 mmp9 ncam1 pmch ptk2 pxn sh3pxd2a src syt2 tuba4b tubb2b tubb3 was wasl
???displayArticle.antibodies??? Actr3 Ab1 B3gat1 Ab3 Cttn Ab1 Enah Ab1 GFP Ab18 Itgb1 Ab1 Mmp14 Ab1 Ptk2 Ab1 Pxn Ab2 Sh3pxd2a Ab1 Src Ab2 Sv2a Ab1 Syt2 Ab1 Tuba4b Ab5 Tubulin I+II Ab1 Wasl Ab1
???attribute.lit??? ???displayArticles.show???
Fig. 1. Growth cones contain F-actin-rich foci within their central domain in vitro and in vivo. (A,B) Confocal images of phalloidin-labeled spinal neuron (A) or retinal ganglion cell (B) growth cones with F-actin foci (arrowheads) cultured on different substrata. (C,D). Quantification of foci number (C; nâ¥26) and area (D; nâ¥51) in growth cones on different substrata. Lines represent the mean intensity. (E) TIRF images of a live spinal growth cone on laminin expressing GFP-β-actin. Note stable F-actin foci in the C-domain as the growth cone advances (red boxes). (F,G) Confocal z-series projections of whole-mount Xenopus spinal cords with F-actin-labeled motoneurons and commissural interneurons by using targeted expression of mCh-UtrCH. (F) Lateral view shows motoneuron axons extending along the ventral fascicle with F-actin foci (arrowheads). (G) Ventral view of a spinal cord showing commissural interneuron growth cones at the midline. Scale bars: 5â µm (A,B,E,G); 10â µm (F). FN, fibronectin; LN, laminin; PDL, poly-d-lysine. | |
Fig. 2. F-actin foci colocalize with β1 integrin receptors and the PC proteins PXN and FAK in growth cones. (A-C) Confocal microscopy images of growth cones cultured on laminin and immunolabeled for β1 integrin (A), pY118-PXN (B) or pY397-FAK (C). (Aâ²-Câ²) Phalloidin staining. (Aâ²-Câ²) Merged images of immunolabeling (green) and F-actin staining (red). Note that β1 integrin targets to filopodia tips (solid arrowheads), as well as to F-actin foci (open arrowheads). Also note that pY118-PXN and pY397-FAK colocalize with some (open arrowheads), but not all, F-actin foci (solid arrowheads). (D) A minority of F-actin foci contain pY118-PXN. ***P<0.001, unpaired t-test, n=68. (E,F) Inverse contrast TIRF images of a live spinal neuron growth cone on laminin expressing both paxillin (PXN)-GFP (E) and mCh-UtrCH (F). (G) In a merged pseudo-colored image, PXN (green) colocalizes with some (open arrowheads), but not all F-actin foci (red, solid arrowheads). Scale bars: 5â µm (A,B,E-G). | |
Fig. 3. F-actin foci are sites of actin polymerization. (A-Aâ²) Confocal microscopy images of a growth cone on laminin stained for G-actin (A) and F-actin (Aâ²). Note the colocalization of monomeric actin with F-actin foci in the merged image (Aâ², arrowheads). (B-Bâ²) Time-lapse TIRF images of a live growth cone cultured on laminin and labeled with TMR-KabC. Note that stable barbed ends (arrowhead). (C) Kymograph from the boxed region in B illustrating the rearward flow of KabC-capped actin filaments (angled lines) in the P-domain and stable actin foci in the C-domain (arrowhead). (D-Dâ²) Confocal microscopy images of a live growth cone expressing GFP-β-actin (D) together with mCh-UtrCH (Dâ²) and an image merge (Dâ²) during photobleaching of GFP-β-actin. Note photobleaching (0â s) and recovery (10â s) of GFP-β-actin at an mCh-UtrCH-labeled foci (arrowhead). (E) Normalized fluorescence recovery rate after photobleaching of GFP-β-actin within regions over foci (on foci, upper graph) and in regions adjacent to foci (off foci, lower graph). More rapid recovery of mCh-UtrCH is likely to be the result of a more rapid exchange rate of F-actin binding protein (nâ¥59). (F-Fâ²) Confocal microscopy images of a live growth cone expressing PA-GFP-γ-actin (F) together with mCh-UtrCH (Fâ²) and an image merge (Fâ²) during photoactivation of PA-GFP-γ-actin. Note rapid photoactivation (0â s) and decay of PA-GFP-γ-actin at an mCh-UtrCH-labeled F-actin foci (arrowhead). (G) Normalized fluorescence decay rate after photoactivation of PA-GFP-γ-actin at foci together with slow bleaching of mCh-UtrCH signal (upper graph). The ratio of PA-GFP-γ-actin fluorescence versus that of mCh-UtrCH bleaching provides a measure of γ-actin turnover (lower graph) (nâ¥59). Scale bars: 5â µm (A,B,D,F); 2.5â μm (insets in D,F). | |
Fig. 4. F-actin foci colocalize with Cttn and other invadosome modulators within growth cones. (A-D) Confocal images of growth cones cultured on laminin and immunolabeled for Cttn (A), Arp3 (B), N-WASP (C) and Mena (D). (Aâ²,Dâ²) Phalloidin labeling of F-actin. (Aâ²-Dâ²) Merged images of the immunolabeling (green) and F-actin labeling (red). Note the strong colocalization of F-actin foci with immunolabeled proteins (arrowheads). (E-Eâ²) TIRF images of a live growth cone on laminin expressing both GFP-α-actinin (E) and mCh-UtrCH (Eâ²). Note in the merged image (Eâ²) that α-actinin targets to mCh-UtrCH-labeled F-actin foci (arrowheads). Scale bar: 5â µm. | |
Fig. 5. F-actin foci colocalize with Src and Tks5, and require active Src and lipid rafts for their formation in growth cones. (A) Reverse transcription PCR amplification of Tks4 and Tks5 from stage-22 and stage-25 Xenopus spinal cord. (B) Western blot of Tks5 from stage-24 Xenopus spinal cord. (C,D) Confocal images of growth cones cultured on laminin and immunolabeled for Tks5 (C) and pY418-Src (D). (Câ²,Dâ²) Immunolabeling of Cttn. (Câ²,Dâ²) Phalloidin labeling of F-actin. (Câ´-Dâ´) Merged images of Tks5 or Src (blue), Cttn (green) and F-actin (red). Note colocalization of Tks5 and active Src with Cttn at growth cone invadosomes (arrows). (E) TIRF image of a live growth cone on laminin expressing both Tks5-GFP (green) and mCh-UtrCH (magenta). Note that Tks5 targets to mCh-UtrCH-labeled F-actin foci (arrows). (F) Invadosome number is significantly reduced by treatment with 5â µM SU6656, 1â µM PP2 or 20â µM LY294002 for 30â min. ***P<0.0001, KruskalâWallis test with Dunn's post-hoc analysis, nâ¥75. (G) Invadosome lifetime in GFP-β-actin expressing growth cones is significantly reduced by inhibition of Src with 1â µM PP2. ***P<0.001, unpaired t-test, nâ¥99. (H) TIRF images of a live growth cone on laminin expressing GFP-β-actin before (left) and after (right) treatment with 2.5â µM MβCD. (I) The number of total (left) and stable (right) invadosomes in GFP-β-actin expressing growth cones is reduced after treatment with 1â µM MβCD. *P<0.05, paired t-test, n=7. (J) Invadosome lifetime in GFP-β-actin expressing growth cones is significantly reduced by cholesterol depletion with 1â µM MβCD. ***P<0.001, paired t-test, nâ¥57. Scale bars: 5â µm (C-E,H). ns, not significant. | |
Fig. 6. F-actin-rich protrusion from the central domain of growth cones are detected by 3D SIM. (A,B) SIM images of Xenopus spinal neuron growth cones on laminin (A) or thin gelatin (B), fixed and stained for F-actin with Alexa-568 phalloidin. Note the cross-linked actin meshwork within the peripheral veil and the F-actin-rich foci within the growth cone central domain (arrowhead in A and red box in B). (C) 2.5à zoom of the boxed region in B. (D) Orthogonal view (y-z) through the F-actin-rich foci shown in C. Note this F-actin foci spans from the basal (Ba) substratum to the apical (Ap) membrane where it protrudes from the growth cone surface (arrowhead). (E,Eâ²) SIM images of an iPSC-derived human forebrain neuron growth cone on laminin, fixed and stained for F-actin with Alexa-568 phalloidin (E) and immunolabeled for βIII-tubulin (Eâ²). Note the F-actin-rich foci located within the growth cone central domain (arrowhead). (Eâ²) Merged image of F-actin (magenta) and βIII-tubulin (green) labeling. (F-Fâ²) Orthogonal view (x-z) images through the F-actin-rich foci shown in E-Eâ². Note how MTs track along F-actin within the apical protrusion (arrowhead). (G-Gâ²) 3D SIM images of a Xenopus spinal neuron growth cone in a collagen-I gel stained for F-actin (G) with phalloidin and immunolabeled for Cttn (Gâ²). Note in the merge image (Gâ²) F-actin-rich foci (purple) within the C-domain colocalize with Cttn (green, arrowheads in Gâ²). (H) Orthogonal view of a triple-labeled growth cone (Cttn, green; F-actin, red; βI+II tubulin, blue) in a collagen-I gel showing apical (white arrowheads) and basal protrusions (red arrowhead). (I-K) 3D SIM images of a peripheral Rohon-Beard growth cone in the skin immunolabeled for NCAM (green) and Cttn (red) and viewed at three orientations. Cttn-containing NCAM puncta in the C-domain viewed in x-y (I, solid arrowhead) associates with an apical protrusion viewed as a 90° rotation along the x-axis (J, solid arrowhead). A second prominent apical protrusion (open arrowheads) extends â¼10â µm toward the peripheral skin as seen in a 90° rotation along the y-axis (J,K). Scale bars: 5â µm (A,B,E,G,I(x,y),J(z),K(z)); 1â µm (C,D); 2â µm (F,H). | |
Fig. 7. Spinal neurons express MMPs, and growth cones exhibit invadosome-targeted protease activity. (A) Reverse transcription PCR amplification of MMP2, MMP9 and MMP14 from stage-24 Xenopus spinal cord. (B) Western blot of MMP14 from stage-24 Xenopus spinal cord. (C) Gelatin zymogram of MMP9 (â¼90â kDa) and MMP2 (70â kDa) along with their pro-forms (â¼110â kDa and â¼75â kDa, respectively) from stage-24 Xenopus spinal cord. (D-F) Confocal images of a spinal neuron grown on laminin and immunolabeled for MMP14 (MT1-MMP) (D), with F-actin-labeled with phalloidin (E) and an image merge (F) of MMP14 (green) and F-actin (magenta). Note colocalization of MMP14 puncta at F-actin foci (arrows). (G,H) 3D rendering view of SIM images of a human forebrain neuron growth cone (from Fig. 6E) triple-labeled for F-actin (red), βIII tubulin (blue) and ADAM17 (green). A view of the apical surface (G) shows an F-actin foci in the central domain (arrowhead), which is revealed to be an apically directed protrusion in a lateral view (H) with ADAM17 at the protrusion tip (arrowhead). (I-L) Gelatin degradation by a spinal neuron growth cone occurs near F-actin foci. (I) Oregon Green gelatin used as the substratum. (J) Growth cone labeled with Alexa-546 phalloidin. (K) Merged image of the gelatin (green) and F-actin (magenta) labels. Note colocalization of F-actin foci with areas of gelatin degradation (arrowheads). (L) Quantification of gelatin degradation for the total growth cone (Tot. GC) and at growth cone invadosomes (GCI) compared to background fluorescence. Gelatin degradation at invadosomes was inhibited by treatment with 10â µM GM6001, 2â µM PP2, 5â µM SU6656, 2.5â µM MβCD and in growth cones expressing δPX-Tks5-GFP. ***P<0.0001, KruskalâWallis test with Dunn's post-hoc analysis, nâ¥22. Scale bars: 5â µm (D-F); 3â µm (G,H); 10â µm (I-K). | |
Fig. 8. Motoneuron growth cones in the spinal cord extend invadosome-like protrusions toward the peripheral myotome, which are necessary for proper axon extension into the periphery. (A,B) Maximum z-series projected images of a whole-mount embryo (lateral view, anterior left) with descending motoneuron growth cones on the ventral fascicle labeled with GFP by using targeted blastomere injection. This embryo was immunolabeled for βI+II tubulin (A) and GFP (B). (C) Merged image of motoneurons labeled for tubulin (red) and GFP (green) showing a robust protrusion that extends toward the notochord (n) from the central domain of the lead growth cone. Note that a MT has polymerized into this invadosome-like protrusion (A, arrowhead) that extends diagonally away from the spinal cord, as seen in an x-z view (C, inset). (D) Maximum z-series projected image (inverted contrast) of a whole-mount embryo (lateral view, anterior left) immunolabeled with the Znp-1 antibody. Note several peripheral axons and fine protrusions extend from motoneurons (arrows). (E) Magnified image from the boxed region in D shows a terminal motoneuron growth cone with many fine protrusions. (F) x-z view resampled along the dashed line in E shows an invadosome-like protrusion that extends deep into the lateral tissue (arrow). (G,H) Maximum z-series projected images of whole-mount embryos (lateral view, anterior left) expressing GFP (G) or δPX-Tks5-GFP (H) in motoneurons. Embryos were immunolabeled for βI+II tubulin (red) and GFP (green). Note that several peripheral GFP-expressing motoneuron axons with growth cones (G, arrowheads) have exited the spinal cord en route to the peripheral myotome, whereas motoneurons expressing δPX-Tks5-GFP remain within the spinal cord (H, arrows). (I) The percentage of tubulin-positive peripheral motoneuron axons that express δPX-Tks5-GFP is significantly less than that expressing GFP in control embryos (see Materials and Methods). *P<0.05, Fisher's exact test. The n values for numbers of peripheral axons (tubulin-positive, GFP-positive), image z stacks and embryos, respectively, are 64, 14, 28, 7 for control and 140, 16, 32, 8 for experimental conditions. Scale bars: 10â µm (A-C); 30â µm (D,G,H). | |
Fig. S1. Mouse and human neuronal growth cones form F-actin rich foci. F-actin in growth cones was labeled with fluorescent phalloidin and imaged by confocal microscopy. A. A Xenopus spinal neuron growth cone cultured on bare glass. B-C. Mouse embryonic cortical (B) and hippocampal (C) growth cones on PDL-L1. D-F. Growth cones of human forebrain (D), motor (E) and RGC (F) neurons differentiated from iPSCs and plated on PDLLN. Note F-actin rich foci located within the C-domain of all growth cones (arrowheads). Scale, 5 μm (A-F). | |
Fig. S5. Xenopus spinal axons extend deep into a 3D collagen gel. Confocal Z-series 3D reconstruction of a Xenopus spinal explant cultured on top of a collagen-1 gel. The explant was fixed and stained for Factin with phalloidin (green) and immuolabeled for MTs (red). The deepest axons tipped by growth cones (arrows) extend greater than 300 μm into the gel. | |
Fig. S7. Dominant negative Tks5, Tks5δPX, attenuates gelatin degradation. A-Aâ. Confocal image of a Xenopus neural crest cell on Oregon green 488 gelatin (green in merge), fixed and stained for F-actin (magenta in merge) with Alexa-546 phalloidin. Note the sites of gelatin degradation under invadosomes in the merge (Aâ). B-Bâââ. Confocal image of a Xenopus neural crest cell expressing Tks5δPX (B, blue in merge) on Cy3- labeled gelatin (Bâ, green in merge), fixed and stained for F-actin (Bâ, red in merge) with Alexa-546 phalloidin. Note the lack of gelatin degradation under invadosomes in the merge (Bâââ). Scale, 10μm. | |
Fig. S8. Model illustrating F-actin rich foci as growth cones invadosomes. A. SIM image of a Xenopus spinal neuron growth cone on LN, fixed and stained for F-actin (green) with Alexa-568 phalloidin and immunolabeled for βI/II-tubulin (magenta). Note the F-actin rich foci within the growth cone C-domain (arrows). B. Illustration of a cross-sectioned growth cone responding to environmental cues by remodeling the ECM with F-actin foci that become protruding invadosomes. Note how invadosomal F-actin orients perpendicular to the planar F-actin network within the growth cone. C. Magnified schematic view of a single cross-sectioned growth cone invadosome. Growth cones first establish adhesions with the ECM through the interaction of integrins, Src and adhesion proteins such as paxillin and FAK. Once localized to adhesion sites, Src may phosphorylate Tks5, as well as proteins implicated in lipid raft formation. Phosphorylated Tks5 targets to lipid rafts and initiates actin polymerization through cortactin, N-WASP, the Arp2/3 complex and Ena/Vasp proteins. This network of branched actin assembles F-actin rich columns that span the width of the growth cone and extend protrusions orthogonal to the plane of outgrowth. Membrane bound and secreted proteases at the tips of invadosomes begin to degrade the ECM, allowing the actin column to transition into a 3-dimensional membrane protrusion. Invadosomal protrusions, formed of both branched and unbranched actin filaments, are stabilized by proteins such as α-actinin. In mature invadosomes, MTs polymerize into the protrusion providing increased stability and the delivery of vesicular cargo, such as proteases and guidance cue receptors. Growth cone invadosomes may represent a novel mechanism for growth cones to respond to environmental cues by remodeling surrounding tissues with 3-dimensional projections during axon guidance. |
References [+] :
Abram,
The adaptor protein fish associates with members of the ADAMs family and localizes to podosomes of Src-transformed cells.
2003, Pubmed
Abram, The adaptor protein fish associates with members of the ADAMs family and localizes to podosomes of Src-transformed cells. 2003, Pubmed
Alexander, Extracellular matrix rigidity promotes invadopodia activity. 2008, Pubmed
Artym, ECM degradation assays for analyzing local cell invasion. 2009, Pubmed
Bai, Presenilin-dependent receptor processing is required for axon guidance. 2011, Pubmed
Boateng, Spatiotemporal regulation of Src and its substrates at invadosomes. 2012, Pubmed
Bowes, Xenbase: gene expression and improved integration. 2010, Pubmed , Xenbase
Browne, Transmembrane semaphorin5B is proteolytically processed into a repulsive neural guidance cue. 2012, Pubmed
Chan, FAK alters invadopodia and focal adhesion composition and dynamics to regulate breast cancer invasion. 2009, Pubmed
Chen, Targeting of retinal axons requires the metalloproteinase ADAM10. 2007, Pubmed , Xenbase
Coleman, The Adam family metalloprotease Kuzbanian regulates the cleavage of the roundabout receptor to control axon repulsion at the midline. 2010, Pubmed
Collin, Self-organized podosomes are dynamic mechanosensors. 2008, Pubmed
Courtneidge, Cell migration and invasion in human disease: the Tks adaptor proteins. 2012, Pubmed
Decourt, Cortactin colocalizes with filopodial actin and accumulates at IgCAM adhesion sites in Aplysia growth cones. 2009, Pubmed
Dent, The growth cone cytoskeleton in axon outgrowth and guidance. 2011, Pubmed
Fambrough, The cell surface metalloprotease/disintegrin Kuzbanian is required for axonal extension in Drosophila. 1996, Pubmed
Galko, Function of an axonal chemoattractant modulated by metalloprotease activity. 2000, Pubmed
Gamm, A novel serum-free method for culturing human prenatal retinal pigment epithelial cells. 2008, Pubmed
Gomez, Chick sensory neuronal growth cones distinguish fibronectin from laminin by making substratum contacts that resemble focal contacts. 1996, Pubmed
Gómez, Working with Xenopus spinal neurons in live cell culture. 2003, Pubmed , Xenbase
Guirland, Lipid rafts mediate chemotropic guidance of nerve growth cones. 2004, Pubmed , Xenbase
Gutiérrez-Fernández, Plasminogen enhances neuritogenesis on laminin-1. 2009, Pubmed
Hall, Rho and Ras GTPases in axon growth, guidance, and branching. 2010, Pubmed
Hattori, Regulated cleavage of a contact-mediated axon repellent. 2000, Pubmed
Hayashita-Kinoh, Membrane-type 5 matrix metalloproteinase is expressed in differentiated neurons and regulates axonal growth. 2001, Pubmed
Hehr, Matrix metalloproteinases are required for retinal ganglion cell axon guidance at select decision points. 2005, Pubmed , Xenbase
Hoshino, Network analysis of the focal adhesion to invadopodia transition identifies a PI3K-PKCα invasive signaling axis. 2012, Pubmed
Hoshino, Signaling inputs to invadopodia and podosomes. 2013, Pubmed
Hu, Differentiation of spinal motor neurons from pluripotent human stem cells. 2009, Pubmed
Huang, BDNF promotes target innervation of Xenopus mandibular trigeminal axons in vivo. 2007, Pubmed , Xenbase
Juin, Extracellular matrix rigidity controls podosome induction in microvascular endothelial cells. 2013, Pubmed
Kanning, Proteolytic processing of the p75 neurotrophin receptor and two homologs generates C-terminal fragments with signaling capability. 2003, Pubmed , Xenbase
Keren, Mechanism of shape determination in motile cells. 2008, Pubmed
Ketschek, Nerve growth factor induces axonal filopodia through localized microdomains of phosphoinositide 3-kinase activity that drive the formation of cytoskeletal precursors to filopodia. 2010, Pubmed
Kirkbride, Cortactin: a multifunctional regulator of cellular invasiveness. 2011, Pubmed
Kolodkin, Mechanisms and molecules of neuronal wiring: a primer. 2011, Pubmed
Kurklinsky, Growth cone morphology and spreading are regulated by a dynamin-cortactin complex at point contacts in hippocampal neurons. 2011, Pubmed
Lee, Dynamic localization of G-actin during membrane protrusion in neuronal motility. 2013, Pubmed , Xenbase
Lee, Regulation of cell survival by secreted proneurotrophins. 2001, Pubmed
Lin, Ephrin-B2-induced cleavage of EphB2 receptor is mediated by matrix metalloproteinases to trigger cell repulsion. 2008, Pubmed
Linder, Degrading devices: invadosomes in proteolytic cell invasion. 2011, Pubmed
Liu, Medial ganglionic eminence-like cells derived from human embryonic stem cells correct learning and memory deficits. 2013, Pubmed
Liu, Laminin-332-beta1 integrin interactions negatively regulate invadopodia. 2010, Pubmed
Lowery, The trip of the tip: understanding the growth cone machinery. 2009, Pubmed , Xenbase
MacGrath, Cortactin in cell migration and cancer at a glance. 2012, Pubmed
Marsick, Activation of ADF/cofilin mediates attractive growth cone turning toward nerve growth factor and netrin-1. 2010, Pubmed , Xenbase
McFarlane, Metalloproteases: carving out a role in axon guidance. 2003, Pubmed
Medeiros, Myosin II functions in actin-bundle turnover in neuronal growth cones. 2006, Pubmed
Miller, Matrix metalloproteinases promote motor axon fasciculation in the Drosophila embryo. 2008, Pubmed
Moon, Adjacent pioneer commissural interneuron growth cones switch from contact avoidance to axon fasciculation after midline crossing. 2005, Pubmed , Xenbase
Murphy, The 'ins' and 'outs' of podosomes and invadopodia: characteristics, formation and function. 2011, Pubmed
Murphy, A Src-Tks5 pathway is required for neural crest cell migration during embryonic development. 2011, Pubmed
Myers, Focal adhesion kinase promotes integrin adhesion dynamics necessary for chemotropic turning of nerve growth cones. 2011, Pubmed , Xenbase
Oikawa, Tks5-dependent formation of circumferential podosomes/invadopodia mediates cell-cell fusion. 2012, Pubmed
Pankratz, Directed neural differentiation of human embryonic stem cells via an obligated primitive anterior stage. 2007, Pubmed
Petchprayoon, Fluorescent kabiramides: new probes to quantify actin in vitro and in vivo. 2005, Pubmed
Philippar, A Mena invasion isoform potentiates EGF-induced carcinoma cell invasion and metastasis. 2008, Pubmed
Poincloux, Matrix invasion by tumour cells: a focus on MT1-MMP trafficking to invadopodia. 2009, Pubmed
Renaudin, Organization of point contacts in neuronal growth cones. 1999, Pubmed
Robles, Focal adhesion kinase signaling at sites of integrin-mediated adhesion controls axon pathfinding. 2006, Pubmed , Xenbase
Rozen, Primer3 on the WWW for general users and for biologist programmers. 2000, Pubmed
Santiago-Medina, Imaging adhesion and signaling dynamics in Xenopus laevis growth cones. 2012, Pubmed , Xenbase
Santiago-Medina, PAK-PIX interactions regulate adhesion dynamics and membrane protrusion to control neurite outgrowth. 2013, Pubmed , Xenbase
Schimmelpfeng, The function of leak and kuzbanian during growth cone and cell migration. 2001, Pubmed
Seals, The adaptor protein Tks5/Fish is required for podosome formation and function, and for the protease-driven invasion of cancer cells. 2005, Pubmed
Sloane, Functional imaging of tumor proteolysis. 2006, Pubmed
Spillane, The actin nucleating Arp2/3 complex contributes to the formation of axonal filopodia and branches through the regulation of actin patch precursors to filopodia. 2011, Pubmed
Tanaka, Biomolecular mimicry in the actin cytoskeleton: mechanisms underlying the cytotoxicity of kabiramide C and related macrolides. 2003, Pubmed
Toomre, A new wave of cellular imaging. 2010, Pubmed
Walmsley, Zinc metalloproteinase-mediated cleavage of the human Nogo-66 receptor. 2004, Pubmed
Webber, Metalloproteases and guidance of retinal axons in the developing visual system. 2002, Pubmed , Xenbase
Woo, Rac1 and RhoA promote neurite outgrowth through formation and stabilization of growth cone point contacts. 2006, Pubmed , Xenbase
Yamaguchi, Membrane lipids in invadopodia and podosomes: key structures for cancer invasion and metastasis. 2010, Pubmed
Yamaguchi, Phosphoinositide 3-kinase signaling pathway mediated by p110α regulates invadopodia formation. 2011, Pubmed
Yang, Pro-BDNF-induced synaptic depression and retraction at developing neuromuscular synapses. 2009, Pubmed , Xenbase
Yong, Metalloproteinases in biology and pathology of the nervous system. 2001, Pubmed
Zuo, Neuronal matrix metalloproteinase-2 degrades and inactivates a neurite-inhibiting chondroitin sulfate proteoglycan. 1998, Pubmed