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Marc Tessierlavigne - One of the best experts on this subject based on the ideXlab platform.

  • long range guidance of spinal commissural axons by Netrin1 and sonic hedgehog from midline floor plate cells
    Neuron, 2019
    Co-Authors: Shirin Makihara, Frédéric Charron, Alain Chedotal, Nicolas Renier, Patricia T Yam, Shaun Teo, Nursen Balekoglu, Juan Antonio Morenobravo, Olav Olsen, Marc Tessierlavigne
    Abstract:

    Summary An important model for axon pathfinding is provided by guidance of embryonic commissural axons from dorsal spinal cord to ventral midline floor plate (FP). FP cells produce a chemoattractive activity, comprised largely of Netrin1 (FP-Netrin1) and Sonic hedgehog (Shh), that can attract the axons at a distance in vitro. Netrin1 is also produced by ventricular zone (VZ) progenitors along the axons’ route (VZ-Netrin1). Recent studies using region-specific Netrin1 deletion suggested that FP-Netrin1 is dispensable and VZ-Netrin1 sufficient for Netrin guidance activity in vivo. We show that removing FP-Netrin1 actually causes guidance defects in spinal cord consistent with long-range action (i.e., over hundreds of micrometers), and double mutant analysis supports that FP-Netrin1 and Shh collaborate to attract at long range. We further provide evidence that Netrin1 may guide via chemotaxis or haptotaxis. These results support the model that Netrin1 signals at both short and long range to guide commissural axons in spinal cord.

  • operational redundancy in axon guidance through the multifunctional receptor robo3 and its ligand nell2
    Science, 2015
    Co-Authors: Marc Tessierlavigne, Alexander Jaworski, Irene Tom, Raymond K Tong, Holly K Gildea, Alexander W Koch, Lino C Gonzalez
    Abstract:

    Axon pathfinding is orchestrated by numerous guidance cues, including Slits and their Robo receptors, but it remains unclear how information from multiple cues is integrated or filtered. Robo3, a Robo family member, allows commissural axons to reach and cross the spinal cord midline by antagonizing Robo1/2-mediated repulsion from midline-expressed Slits and potentiating deleted in colorectal cancer (DCC)-mediated midline attraction to Netrin-1, but without binding either Slits or Netrins. We identified a secreted Robo3 ligand, neural epidermal growth factor-like-like 2 (NELL2), which repels mouse commissural axons through Robo3 and helps steer them to the midline. These findings identify NELL2 as an axon guidance cue and establish Robo3 as a multifunctional regulator of pathfinding that simultaneously mediates NELL2 repulsion, inhibits Slit repulsion, and facilitates Netrin attraction to achieve a common guidance purpose.

  • structures of Netrin 1 bound to two receptors provide insight into its axon guidance mechanism
    Science, 2014
    Co-Authors: Nicolas Renier, Marc Tessierlavigne, Alexander Antipenko, Dorothea Tzvetkovarobev, Maria Minchenko, Vincenzo Nardidei, Kanagalaghatta R Rajashankar, Juha P Himanen, Dimitar B Nikolov
    Abstract:

    Netrins are secreted proteins that regulate axon guidance and neuronal migration. Deleted in colorectal cancer (DCC) is a well-established Netrin-1 receptor mediating attractive responses. We provide evidence that its close relative neogenin is also a functional Netrin-1 receptor that acts with DCC to mediate guidance in vivo. We determined the structures of a functional Netrin-1 region, alone and in complexes with neogenin or DCC. Netrin-1 has a rigid elongated structure containing two receptor-binding sites at opposite ends through which it brings together receptor molecules. The ligand/receptor complexes reveal two distinct architectures: a 2:2 heterotetramer and a continuous ligand/receptor assembly. The differences result from different lengths of the linker connecting receptor domains fibronectin type III domain 4 (FN4) and FN5, which differs among DCC and neogenin splice variants, providing a basis for diverse signaling outcomes.

  • Netrin 1 is a novel myelin associated inhibitor to axon growth
    The Journal of Neuroscience, 2008
    Co-Authors: Karin Low, Marc Tessierlavigne, Maya Culbertson, Frank Bradke, Mark H Tuszynski
    Abstract:

    We investigated the influence of the bifunctional guidance molecule Netrin-1 on axonal growth in the injured adult spinal cord. In the adult, Netrin-1 is expressed on mature oligodendrocytes, cells of the central canal, and the meninges. Netrin-1 protein in white matter is selectively enriched adjacent to paranodal loops of myelin in nodes of Ranvier. The repulsion-mediating Netrin-1 uncoordinated-5 (UNC5) receptors are expressed by neurons of the corticospinal and rubrospinal projections, and by intrinsic neurons of the spinal cord, both before and after spinal cord injury. Neutralization of Netrin-1 in myelin prepared from adult rat spinal cord using UNC5 receptor bodies increases neurite outgrowth from UNC5-expressing spinal motor neurons in vitro. Furthermore, axon regeneration is inhibited in a Netrin-1-enriched zone, devoid of other myelin-associated inhibitors, within spinal cord lesion sites in vivo. We conclude that Netrin-1 is a novel oligodendrocyte-associated inhibitor that can contribute to axonal growth failure after adult spinal cord injury.

  • axon guidance by diffusible chemoattractants a gradient of Netrin protein in the developing spinal cord
    The Journal of Neuroscience, 2006
    Co-Authors: Timothy E. Kennedy, Hao Wang, Wallace F Marshall, Marc Tessierlavigne
    Abstract:

    Gradients of diffusible long-range attractant and repellent proteins have been proposed to guide growing axons during nervous system development, but such gradients have never been visualized directly. In the embryonic spinal cord, commissural axons pioneer a circumferential trajectory to the floor plate at the ventral midline directed by secreted proteins of the Netrin family. In the embryonic chick spinal cord Netrin-1 mRNA is expressed by floor plate cells and Netrin-2 mRNA by neural epithelial cells. Antibodies to the two Netrins reveal a gradient of Netrin protein directly in the path of commissural axons. The Netrin-1 gradient itself extends many cell diameters dorsal to the floor plate, the site of Netrin-1 expression. A similar distribution of Netrin-1 protein has been detected in embryonic rat and mouse spinal cord. The detection of a gradient of Netrin-1 protein supports the operation of long-range chemotropic mechanisms in the developing nervous system.

Timothy E. Kennedy - One of the best experts on this subject based on the ideXlab platform.

  • Cellular/Molecular Deleted in Colorectal Cancer Binding Netrin-1 Mediates Cell Substrate Adhesion and Recruits Cdc42, Rac1, Pak1, and N-WASP into an Intracellular Signaling Complex That Promotes Growth Cone Expansion
    2016
    Co-Authors: Masoud Shekarabi, Simonw Moore, Nicolas X. Tritsch, Stephen J. Morris, Jean-francois Bouchard, Timothy E. Kennedy
    Abstract:

    Extracellular cues direct axon extension by regulating growth conemorphology. The Netrin-1 receptor deleted in colorectal cancer (DCC) is required for commissural axon extension to the floor plate in the embryonic spinal cord. Here we demonstrate that challenging embryonic rat spinal commissural neuronswith Netrin-1, either in solution or as a substrate, causes DCC-dependent increases in growth cone surface area and filopodia number, which we term growth cone expansion. We provide evidence that DCC influences growth cone morphology by at least two mechanisms. First, DCC mediates an adhesive interaction with substrate-bound Netrin-1. Second, Netrin-1 binding to DCC recruits an intracellular signaling complex that directs the organization of actin. We show that Netrin-1-induced growth cone expansion requires Cdc42 (cell division cycle 42), Rac1 (Ras-related C3 botulinum toxin substrate 1), Pak1 (p21-activated kinase), andN-WASP (neuronalWiskott–Aldrich syndromeprotein) and that the application of Netrin-1 rapidly activates Cdc42, Rac1, andPak1. Furthermore, Netrin-1 recruits Cdc42, Rac1, Pak1, and N-WASP into a complex with the intracellular domain of DCC and Nck1. These findings suggest thatDCC influences growth conemorphology by acting both as a transmembrane bridge that links extracellular Netrin-1 to the actin cytoskeleton and as the core of a protein complex that directs the organization of actin. Key words: embryonic spinal commissural neuron; chemotropism; chemotropic; axon guidance; motility; DCC; netri

  • A central role for RhoA during oligodendroglial maturation in the switch from Netrin-1-mediated chemorepulsion to process elaboration.
    Journal of neurochemistry, 2010
    Co-Authors: Sathyanath Rajasekharan, Jenea M Bin, Jack P. Antel, Timothy E. Kennedy
    Abstract:

    J. Neurochem. (2010) 113, 1589–1597. Abstract The guidance cue Netrin-1 and its receptor Deleted in Colorectal Cancer play distinct roles during different stages of oligodendrocyte development. A gradient of Netrin-1 repels migrating oligodendrocyte precursor cells (OPCs) in the embryonic spinal cord by promoting process collapse, but later in development Netrin-1 increases oligodendrocyte process extension and branching. Here we investigate the intracellular mechanism that governs this switch in response to Netrin-1, and focus on the role of the GTPase RhoA and its effector Rho Kinase (ROCK) downstream of Netrin-1 in OPCs and maturing oligodendrocytes. In OPCs, we show that Netrin-1 induces a sustained increase in RhoA activity that requires Deleted in Colorectal Cancer function. Furthermore, we demonstrate that activation of RhoA and ROCK is required for the reduction in OPC process length triggered by Netrin-1, and for the chemorepellent response made by OPCs to Netrin-1. Unlike OPCs, application of Netrin-1 to oligodendrocytes decreases RhoA activity. We demonstrate that inactivation of RhoA is essential for Netrin-1 to increase oligodendrocyte process branching. We conclude that Netrin-1 induces distinct morphological responses in OPCs and oligodendrocytes through differential regulation of RhoA activity.

  • The Netrin protein family
    Genome Biology, 2009
    Co-Authors: Sathyanath Rajasekharan, Timothy E. Kennedy
    Abstract:

    The name Netrin is derived from the Sanskrit Netr , meaning 'guide'. Netrins are a family of extracellular proteins that direct cell and axon migration during embryogenesis. Three secreted Netrins (Netrins 1, 3 and 4), and two glycosylphosphatidylinositol (GPI)-anchored membrane proteins, Netrins G1 and G2, have been identified in mammals. The secreted Netrins are bifunctional, acting as attractants for some cell types and repellents for others. Receptors for the secreted Netrins include the Deleted in Colorectal Cancer (DCC) family, the Down's syndrome cell adhesion molecule (DSCAM), and the UNC-5 homolog family: Unc5A, B, C and D in mammals. Netrin Gs do not appear to interact with these receptors, but regulate synaptic interactions between neurons by binding to the transmembrane Netrin G ligands NGL1 and 2. The chemotropic function of secreted Netrins has been best characterized with regard to axon guidance during the development of the nervous system. Extending axons are tipped by a flattened, membranous structure called the growth cone. Multiple extracellular guidance cues direct axonal growth cones to their ultimate targets where synapses form. Such cues can be locally derived (short-range), or can be secreted diffusible cues that allow target cells to signal axons from a distance (long-range). The secreted Netrins function as short-range and long-range guidance cues in different circumstances. In addition to directing cell migration, functional roles for Netrins have been identified in the regulation of cell adhesion, the maturation of cell morphology, cell survival and tumorigenesis.

  • soluble adenylyl cyclase is not required for axon guidance to Netrin 1
    The Journal of Neuroscience, 2008
    Co-Authors: Simonw Moore, Philip A. Barker, Karen Lai Wing Sun, Fang Xie, Marco Conti, Timothy E. Kennedy
    Abstract:

    During development, axons are directed to their targets by extracellular guidance cues. The axonal response to the guidance cue Netrin-1 is profoundly influenced by the concentration of cAMP within the growth cone. In some cases, cAMP affects the sensitivity of the growth cone to Netrin-1, whereas in others it changes the response to Netrin-1 from attraction to repulsion. The effects of cAMP on Netrin-1 action are well accepted, but the critical issue of whether cAMP production is activated by a Netrin-1 induced signaling cascade remains uncertain. A previous report has suggested that axon guidance in response to Netrin-1 requires cAMP production mediated by soluble adenyl cyclase (sAC). We have used genetic, molecular and biochemical strategies to assess this issue. Surprisingly, we found only extremely weak expression of sAC in embryonic neurons and determined that, under conditions where Netrin-1 directs axonal pathfinding, exposure to Netrin-1 does not alter cAMP levels. Furthermore, although Netrin-1-deficient mice exhibit major axon guidance defects, we show that pathfinding is normal in sAC-null mice. Therefore, although cAMP can alter the response of axons to Netrin-1, we conclude that Netrin-1 does not alter cAMP levels in axons attracted by this cue, and that sAC is not required for axon attraction to Netrin-1.

  • axon guidance by diffusible chemoattractants a gradient of Netrin protein in the developing spinal cord
    The Journal of Neuroscience, 2006
    Co-Authors: Timothy E. Kennedy, Hao Wang, Wallace F Marshall, Marc Tessierlavigne
    Abstract:

    Gradients of diffusible long-range attractant and repellent proteins have been proposed to guide growing axons during nervous system development, but such gradients have never been visualized directly. In the embryonic spinal cord, commissural axons pioneer a circumferential trajectory to the floor plate at the ventral midline directed by secreted proteins of the Netrin family. In the embryonic chick spinal cord Netrin-1 mRNA is expressed by floor plate cells and Netrin-2 mRNA by neural epithelial cells. Antibodies to the two Netrins reveal a gradient of Netrin protein directly in the path of commissural axons. The Netrin-1 gradient itself extends many cell diameters dorsal to the floor plate, the site of Netrin-1 expression. A similar distribution of Netrin-1 protein has been detected in embryonic rat and mouse spinal cord. The detection of a gradient of Netrin-1 protein supports the operation of long-range chemotropic mechanisms in the developing nervous system.

Holger K Eltzschig - One of the best experts on this subject based on the ideXlab platform.

  • Netrin1 produced by neural progenitors not floor plate cells is required for axon guidance in the spinal cord
    Neuron, 2017
    Co-Authors: Supraja G Varadarajan, Tzu Jen Kao, Artur Kania, Jennifer H Kong, Keith D Phan, Carmen S Panaitof, Julie Cardin, Holger K Eltzschig, Bennett G Novitch
    Abstract:

    Netrin1 has been proposed to act from the floor plate (FP) as a long-range diffusible chemoattractant for commissural axons in the embryonic spinal cord. However, Netrin1 mRNA and protein are also present in neural progenitors within the ventricular zone (VZ), raising the question of which source of Netrin1 promotes ventrally directed axon growth. Here, we use genetic approaches in mice to selectively remove Netrin from different regions of the spinal cord. Our analyses show that the FP is not the source of Netrin1 directing axons to the ventral midline, while local VZ-supplied Netrin1 is required for this step. Furthermore, rather than being present in a gradient, Netrin1 protein accumulates on the pial surface adjacent to the path of commissural axon extension. Thus, Netrin1 does not act as a long-range secreted chemoattractant for commissural spinal axons but instead promotes ventrally directed axon outgrowth by haptotaxis, i.e., directed growth along an adhesive surface.

  • neuronal guidance molecule Netrin 1 attenuates inflammatory cell trafficking during acute experimental colitis
    Gut, 2012
    Co-Authors: Carol M Aherne, Colm B Collins, Joanne C Masterson, Marco Tizzano, Theresa A Boyle, Joseph A Westrich, Jason A Parnes, Glenn T Furuta, Jesus Riveranieves, Holger K Eltzschig
    Abstract:

    Background Inflammatory bowel diseases, encompassing Crohn9s disease and ulcerative colitis, are characterised by persistent leucocyte tissue infiltration leading to perpetuation of an inappropriate inflammatory cascade. The neuronal guidance molecule Netrin-1 has recently been implicated in the orchestration of leucocyte trafficking during acute inflammation. We therefore hypothesised that Netrin-1 could modulate leucocyte infiltration and disease activity in a model of inflammatory bowel disease. Design DSS-colitis was performed in mice with partial genetic Netrin-1 deficiency ( Ntn-1 +/− mice) or wild-type mice treated with exogenous Netrin-1 via osmotic pump to examine the role of endogenous and therapeutically administered Netrin-1. These studies were supported by in vitro models of transepithelial migration and intestinal epithelial barrier function. Results Consistent with our hypothesis, we observed induction of Netrin-1 during intestinal inflammation in vitro or in mice exposed to experimental colitis. Moreover, mice with partial Netrin-1 deficiency demonstrated an exacerbated course of DSS-colitis compared to littermate controls, with enhanced weight loss and colonic shortening. Conversely, mice treated with exogenous mouse Netrin-1 experienced attenuated disease severity. Importantly, permeability studies and quantitative assessment of apoptosis reveal that Netrin-1 signalling events do not alter mucosal permeability or intestinal epithelial cell apoptosis. In vivo studies of leucocyte transmigration demonstrate suppression of neutrophil trafficking as a key function mediated by endogenous or exogenously administered Netrin-1. Finally, genetic studies implicate the A2B adenosine receptor in Netrin-1-mediated protection during DSS-colitis. Conclusions The present study identifies a previously unrecognised role for Netrin-1 in attenuating experimental colitis through limitation of neutrophil trafficking.

  • hypoxia inducible factor dependent induction of Netrin 1 dampens inflammation caused by hypoxia
    Nature Immunology, 2009
    Co-Authors: Peter Rosenberger, Holger K Eltzschig, Valbona Mirakaj, Julio C Morotegarcia, Klaus Unertl, Jan M Schwab, Eva Masekowsky, Alice Mager
    Abstract:

    The neuronal guidance molecule Netrin-1 is linked to the coordination of inflammatory responses. Given that mucosal surfaces are particularly prone to hypoxia-elicited inflammation, we sought to determine the function of Netrin-1 in hypoxia-induced inflammation. We detected hypoxia-inducible factor 1alpha (HIF-1alpha)-dependent induction of expression of the gene encoding Netrin-1 (Ntn1) in hypoxic epithelia. Neutrophil transepithelial migration studies showed that by engaging A2B adenosine receptor (A2BAR) on neutrophils, Netrin-1 attenuated neutrophil transmigration. Exogenous Netrin-1 suppressed hypoxia-elicited inflammation in wild-type but not in A2BAR-deficient mice, and inflammatory hypoxia was enhanced in Ntn1(+/-) mice relative to that in Ntn1(+/+) mice. Our studies demonstrate that HIF-1alpha-dependent induction of Netrin-1 attenuates hypoxia-elicited inflammation at mucosal surfaces.

  • hypoxia inducible factor dependent induction of Netrin 1 dampens inflammation caused by hypoxia
    Nature Immunology, 2009
    Co-Authors: Peter Rosenberger, Holger K Eltzschig, Valbona Mirakaj, Julio C Morotegarcia, Klaus Unertl, Jan M Schwab, Eva Masekowsky, Alice Mager
    Abstract:

    Hypoxia incites inflammation, particularly at mucosal surfaces. Eltzschig and colleagues show that hypoxia also suppresses inflammation by inducing expression of the neuronal guidance molecule Netrin-1, which inhibits the transepithelial migration of neutrophils. The neuronal guidance molecule Netrin-1 is linked to the coordination of inflammatory responses. Given that mucosal surfaces are particularly prone to hypoxia-elicited inflammation, we sought to determine the function of Netrin-1 in hypoxia-induced inflammation. We detected hypoxia-inducible factor 1α (HIF-1α)-dependent induction of expression of the gene encoding Netrin-1 (Ntn1) in hypoxic epithelia. Neutrophil transepithelial migration studies showed that by engaging A2B adenosine receptor (A2BAR) on neutrophils, Netrin-1 attenuated neutrophil transmigration. Exogenous Netrin-1 suppressed hypoxia-elicited inflammation in wild-type but not in A2BAR-deficient mice, and inflammatory hypoxia was enhanced in Ntn1+/− mice relative to that in Ntn1+/+ mice. Our studies demonstrate that HIF-1α-dependent induction of Netrin-1 attenuates hypoxia-elicited inflammation at mucosal surfaces.

P. Mehlen - One of the best experts on this subject based on the ideXlab platform.

  • Floor-plate-derived Netrin-1 is dispensable for commissural axon guidance
    Nature, 2017
    Co-Authors: C. Dominici, J.a. Moreno-bravo, S.r. Puiggros, Q. Rappeneau, N. Rama, P. Vieugue, A. Bernet, P. Mehlen, A. Chedotal
    Abstract:

    Netrin-1 is an evolutionarily conserved, secreted extracellular matrix protein involved in axon guidance at the central nervous system midline. Netrin-1 is expressed by cells localized at the central nervous system midline, such as those of the floor plate in vertebrate embryos. Growth cone turning assays and three-dimensional gel diffusion assays have shown that Netrin-1 can attract commissural axons. Loss-of-function experiments further demonstrated that commissural axon extension to the midline is severely impaired in the absence of Netrin-1 (refs 3, 7, 8, 9). Together, these data have long supported a model in which commissural axons are attracted by a Netrin-1 gradient diffusing from the midline. Here we selectively ablate Netrin-1 expression in floor-plate cells using a Ntn1 conditional knockout mouse line. We find that hindbrain and spinal cord commissural axons develop normally in the absence of floor-plate-derived Netrin-1. Furthermore, we show that Netrin-1 is highly expressed by cells in the ventricular zone, which can release Netrin-1 at the pial surface where it binds to commissural axons. Notably, Ntn1 deletion from the ventricular zone phenocopies commissural axon guidance defects previously described in Ntn1-knockout mice. These results show that the classical view that attraction of commissural axons is mediated by a gradient of floor-plate-derived Netrin-1 is inaccurate and that Netrin-1 primarily acts locally by promoting growth cone adhesion

  • Netrin 1 overexpression in kidney proximal tubular epithelium ameliorates cisplatin nephrotoxicity
    Laboratory Investigation, 2011
    Co-Authors: Amala Rajasundari, P. Mehlen, Laurent Pays, Ganesan Ramesh
    Abstract:

    Netrin-1, a multifunctional laminin-related protein is widely expressed in various tissues, including kidney. The pathophysiological roles of Netrin-1 in toxic acute kidney injury are unknown. To determine the role of Netrin-1 in cisplatin-induced nephrotoxicity, we used Netrin-1 transgenic mice that overexpress Netrin-1 in the proximal tubular epithelium using the fatty acid binding protein promoter. Administration of cisplatin caused severe renal injury in WT mice but not in Netrin-1 transgenic mice. Functional improvement was associated with better preservation of morphology, reduced cytokine expression and oxidative stress in the kidney, and reduced serum and urine cytokine and chemokine levels of transgenic mice as compared with WT mice. Cisplatin induced an increase in neutrophil infiltration into the kidney of WT mice, which was not significantly reduced in Netrin-1 transgenic mice. Interestingly, ischemia reperfusion induced a large increase in apoptosis in WT mice but not in Netrin-1 transgenic mice (215 ± 40 vs 94 ± 20 cells/5 HPF ( × 400), P < 0.0001), which was associated with reduced caspase-3 and p53 activation in the transgenic kidney. These results suggest that Netrin-1 protects renal tubular epithelial cells against cisplatin-induced kidney injury by suppressing apoptosis and inflammation.

  • novel roles for slits and Netrins axon guidance cues as anticancer targets
    Nature Reviews Cancer, 2011
    Co-Authors: P. Mehlen, Celine Delloyebourgeois, Alain Chedotal
    Abstract:

    Over the past few years, several genes, proteins and signalling pathways that are required for embryogenesis have been shown to regulate tumour development and progression by playing a major part in overriding antitumour safeguard mechanisms. These include axon guidance cues, such as Netrins and Slits. Netrin 1 and members of the Slit family are secreted extracellular matrix proteins that bind to deleted in colorectal cancer (DCC) and UNC5 receptors, and roundabout receptors (Robos), respectively. Their expression is deregulated in a large proportion of human cancers, suggesting that they could be tumour suppressor genes or oncogenes. Moreover, recent data suggest that these ligand-receptor pairs could be promising targets for personalized anticancer therapies.

  • interference with Netrin 1 and tumor cell death in non small cell lung cancer
    Journal of the National Cancer Institute, 2009
    Co-Authors: Celine Delloyebourgeois, P. Mehlen, Elisabeth Brambilla, Mariemay Coissieux, Celine Guenebeaud, Remy Pedeux, Virginie Firlej, Florence Cabon, C Brambilla, Agnes Bernet
    Abstract:

    Background Netrin-1 may promote colorectal and breast tumorigenesis, by inhibiting apoptosis induced by its dependence receptors, deleted in colorectal cancer (DCC) and uncoordinated-5-homolog (UNC5H). The status of Netrin-1 and its receptors in non – small cell lung cancer (NSCLC) was unknown. Methods The levels of Netrin-1 and its receptors were analyzed in a panel of 92 NSCLC and 25 human lung cancer cell lines by quantitative reverse transcription – polymerase chain reaction and immunohistochemistry. In lung cancer cell lines that express Netrin-1, the expression of Netrin-1 was inhibited by using small interfering RNA (siRNA), or interference with Netrin-1 was performed by treatment with a decoy recombinant DCC ectodomain protein (DCC-5Fbn). Cell death was monitored with a trypan blue exclusion assay or by measuring caspase-3 activity. The effect of Netrin-1 interference on tumor growth was analyzed by DCC5Fbn intratumoral or Netrin-1 siRNA intraperitoneal injection in mice engrafted with lung cancer cell lines. All statistical tests were two-sided. Results High levels of Netrin-1 were found in 43 of the 92 NSCLC tumor samples (47%). Interference with Netrin-1 in human lung cancer cell lines was associated with UNC5H-mediated cell death in vitro (percentage of cell death in untreated and in DCC-5Fbn – treated cells = 8% and 26%, respectively, difference = 18%, 95% confidence interval [CI] = 10% to 26%; P = .049) and with lung tumor growth inhibition and/or regression in xenografted nude mice (12 mice in DCC-5Fbn – treated group and 13 mice in control group). Mean volume of control and DCC-5Fbn – treated tumors on day 46 was 489 and 84 mm 3 , respectively (difference = 404 mm 3 , 95% CI = 145 to 664 mm 3 ; P < .001). Conclusions Almost half of the NSCLC tissue samples examined expressed high levels of Netrin-1. Extracellular targeting of the interaction between Netrin-1 and UNC5H may be a promising therapeutic approach for NSCLCs that express Netrin-1.

  • Netrin 1 mediated axon outgrowth and camp production requires interaction with adenosine a2b receptor
    Nature, 2000
    Co-Authors: Veronique Corset, Kim T Nguyenbacharvet, Christelle Forcet, Emmanuel Moyse, Alain Chedotal, P. Mehlen
    Abstract:

    The Netrins, a family of laminin-related secreted proteins, are critical in controlling axon elongation and pathfinding1,2,3,4. The DCC (for deleted in colorectal cancer) protein was proposed as a receptor for Netrin-1 in the light of many observations including the inhibition of Netrin-1-mediated axon outgrowth and attraction in the presence of an anti-DCC antiserum5,6,7, the similitude of nervous system defects in DCC and Netrin-1 knockout mice4,8 and the results of receptor swapping experiments9. Previous studies have failed to show a direct interaction of DCC with Netrin-1 (ref. 10), suggesting the possibility of an additional receptor or co-receptor. Here we show that DCC interacts with the membrane-associated adenosine A2b receptor, a G-protein-coupled receptor that induces cAMP accumulation on binding adenosine11. We show that A2b is actually a Netrin-1 receptor and induces cAMP accumulation on binding Netrin-1. Finally, we show that Netrin-1-dependent outgrowth of dorsal spinal cord axons directly involves A2b. Together our results indicate that the growth-promoting function of Netrin-1 may require a receptor complex containing DCC and A2b.

Marc Tessier-lavigne - One of the best experts on this subject based on the ideXlab platform.

  • DSCAM Is a Netrin Receptor that Collaborates with DCC in Mediating Turning Responses to Netrin-1
    Cell, 2008
    Co-Authors: Anatoly Nikolaev, Marc Tessier-lavigne, Geetha Suresh, Yufang Zheng, Elke Stein
    Abstract:

    During nervous system development, spinal commissural axons project toward and across the ventral midline. They are guided in part by Netrin-1, made by midline cells, which attracts the axons by activating the Netrin receptor DCC. However, previous studies suggest that additional receptor components are required. Here, we report that the Down's syndrome Cell Adhesion Molecule (DSCAM), a candidate gene implicated in the mental retardation phenotype of Down's syndrome, is expressed on spinal commissural axons, binds Netrin-1, and is necessary for commissural axons to grow toward and across the midline. DSCAM and DCC can each mediate a turning response of these neurons to Netrin-1. Similarly, Xenopus spinal neurons exogenously expressing DSCAM can be attracted by Netrin-1 independently of DCC. These results show that DSCAM is a receptor that can mediate turning responses to Netrin-1 and support a key role for Netrin/DSCAM signaling in commissural axon guidance in vertebrates.

  • Netrin-3, a Mouse Homolog of Human NTN2L, Is Highly Expressed in Sensory Ganglia and Shows Differential Binding to Netrin Receptors
    The Journal of Neuroscience, 1999
    Co-Authors: Hao Wang, Neal G. Copeland, Debra J. Gilbert, Nancy A. Jenkins, Marc Tessier-lavigne
    Abstract:

    The Netrins comprise a small phylogenetically conserved family of guidance cues important for guiding particular axonal growth cones to their targets. Two Netrin genes, Netrin-1 andNetrin-2, have been described in chicken, but in mouse so far a single Netrin gene, an ortholog of chickNetrin-1, has been reported. We report the identification of a second mouse Netrin gene, which we nameNetrin-3. Netrin-3 does not appear to be the ortholog of chick Netrin-2 but is the ortholog of a recently identified human Netrin gene termed NTN2L(“Netrin-2-like”), as evidenced by a high degree of sequence conservation and by chromosomal localization. Netrin-3is expressed in sensory ganglia, mesenchymal cells, and muscles during the time of peripheral nerve development but is largely excluded from the CNS at early stages of its development. The murine Netrin-3 protein binds to Netrin receptors of the DCC (deleted in colorectal cancer) family [DCC and neogenin] and the UNC5 family (UNC5H1, UNC5H2 and UNC5H3). Unlike chick Netrin-1, however, murine Netrin-3 binds to DCC with lower affinity than to the other four receptors. Consistent with this finding, although murine Netrin-3 can mimic the outgrowth-promoting activity of Netrin-1 on commissural axons, it has lower specific activity than Netrin-1. Thus, like Netrin-1, Netrin-3 may also function in axon guidance during development but may function predominantly in the development of the peripheral nervous system and may act primarily through Netrin receptors other than DCC.

  • Turning of Retinal Growth Cones in a Netrin-1 Gradient Mediated by the Netrin Receptor DCC
    Neuron, 1997
    Co-Authors: José R. De La Torre, Marc Tessier-lavigne, Guo Li Ming, Veit H. Höpker, Mu-ming Poo, Ali Hemmati-brivanlou, Christine E. Holt
    Abstract:

    Netrin-1 promotes outgrowth of axons in vitro through the receptor Deleted in Colorectal Cancer (DCC) and elicits turning of axons within embryonic explants when presented as a point source. It is not known whether Netrin-1 alone can elicit turning nor whether DCC mediates the turning response. We show that Xenopus retinal ganglion cell growth cones orient rapidly toward a pipette ejecting Netrin-1, an effect blocked by antibodies to DCC. In vitro, Netrin-1 induces a complex growth cone morphology reminiscent of that at the optic nerve head, a site of Netrin-1 expression in vivo. These results demonstrate that Netrin-1 can function alone to induce turning, implicate DCC in this response, and support the idea that Netrin-1 contributes to steering axons out of the retina.

  • Vertebrate homologues of C. elegans UNC-5 are candidate Netrin receptors.
    Nature, 1997
    Co-Authors: E.d. Leonardo, Susan L. Ackerman, Kazuko Keino-masu, Masayuki Masu, Lindsay Hinck, Marc Tessier-lavigne
    Abstract:

    In the developing nervous system, migrating cells and axons are guided to their targets by cues in the extracellular environment. The Netrins are a family of phylogenetically conserved guidance cues that can function as diffusible attractants and repellents for different classes of cells and axons. In vertebrates, insects and nematodes, members of the DCC subfamily of the immunoglobulin superfamily have been implicated as receptors that are involved in migration towards Netrin sources. The mechanisms that direct migration away from Netrin sources (presumed repulsions) are less well understood. In Caenorhabditis elegans, the transmembrane protein UNC-5 (ref. 14) has been implicated in these responses, as loss of unc-5 function causes migration defects and ectopic expression of unc-5 in some neurons can redirect their axons away from a Netrin source. Whether UNC-5 is a Netrin receptor or simply an accessory to such a receptor has not, however, been defined. We now report the identification of two vertebrate homologues of UNC-5 which, with UNC-5 and the product of the mouse rostral cerebellar malformation gene (rcm), define a new subfamily of the immunoglobulin superfamily, and whose messenger RNAs show prominent expression in various classes of differentiating neurons. We provide evidence that these two UNC-5 homologues, as well as the rcm gene product, are Netrin-binding proteins, supporting the hypothesis that UNC-5 and its relatives are Netrin receptors.

  • Deleted in Colorectal Cancer (DCC) Encodes a Netrin Receptor
    Cell, 1996
    Co-Authors: Kazuko Keino-masu, Joseph G. Culotti, Masayuki Masu, Lindsay Hinck, E.david Leonardo, Shirley S.-y Chan, Marc Tessier-lavigne
    Abstract:

    The guidance of developing axons in the nervous system is mediated partly by diffusible chemoattractants secreted by axonal target cells. Netrins are chemoattractants for commissural axons in the vertebrate spinal cord, but the mechanisms through which they produce their effects are unknown. We show that Deleted in Colorectal Cancer (DCC), a transmembrane protein of the immunoglobulin superfamily, is expressed on spinal commissural axons and possesses Netrin-1-binding activity. Moreover, an antibody to DCC selectively blocks the Netrin-1-dependent outgrowth of commissural axons in vitro. These results indicate that DCC is a receptor or a component of a receptor that mediates the effects of Netrin-1 on commissural axons, and they complement genetic evidence for interactions between DCC and Netrin homologs in C. elegans and Drosophila.