301
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García Arguinzonis MI, Galler AB, Walter U, Reinhard M, Simm A. Increased spreading, Rac/p21-activated kinase (PAK) activity, and compromised cell motility in cells deficient in vasodilator-stimulated phosphoprotein (VASP). J Biol Chem 2002; 277:45604-10. [PMID: 12055190 DOI: 10.1074/jbc.m202873200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ena/VASP (Drosophila Enabled/vasodilator-stimulated phosphoprotein) proteins are key regulators that promote or inhibit actin-based motility, cell adhesion, and various aspects of axon guidance. However, a conclusive concept of Ena/VASP functions remains elusive. Here, we report that VASP-deficient fibroblasts, despite normal mammalian Enabled (Mena) and Ena-VASP-like (Evl) expression levels, are highly spread. VASP(-/-) cells cover about twice the substrate surface area as wild type cells, while cell volumes are unchanged. In accordance with these observations, activation of the Rac/p21-activated kinase (PAK) pathway, a crucial element in the regulation of cell spreading, is markedly enhanced in VASP(-/-) cells. Thus, in the absence of VASP Rac activation is dramatically prolonged, and PAK activity is elevated after stimulation with platelet-derived growth factor or serum, respectively. Moreover, VASP-deficient cells show compromised migration and reorientation in a wound healing assay. Collectively, our results reveal a VASP-dependent modulation of the Rac/PAK pathway and Rac/PAK-regulated processes, like cell motility and polarization.
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302
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Killeen M, Tong J, Krizus A, Steven R, Scott I, Pawson T, Culotti J. UNC-5 function requires phosphorylation of cytoplasmic tyrosine 482, but its UNC-40-independent functions also require a region between the ZU-5 and death domains. Dev Biol 2002; 251:348-66. [PMID: 12435363 DOI: 10.1006/dbio.2002.0825] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Members of the UNC-5 protein family are transmembrane receptors for UNC-6/netrin guidance cues. To analyze the functional roles of different UNC-5 domains, we sequenced mutations in seven severe and three weak alleles of unc-5 in Caenorhabditis elegans. Four severe alleles contain nonsense mutations. Two weak alleles are truncations of the cytodomain, but one is a missense mutation in an extracellular immunoglobulin domain. To survey the function of different regions of UNC-5, wild-type and mutant unc-5::HA transgenes were tested for their ability to rescue the unc-5(e53) null mutant. Our data reveal partial functional requirements for the extracellular domains and identify a portion of the cytoplasmic juxtamembrane (JM) region as essential for rescue of migrations. When nine cytodomain tyrosines, including seven in the JM region, are mutated to phenylalanine, UNC-5 function and tyrosine phosphorylation are largely compromised. When F482 in the JM region of the mutant protein is reverted to tyrosine, UNC-5 tyrosine phosphorylation and in vivo function are largely recovered, suggesting that Y482 phosphorylation is critical to UNC-5 function in vivo. Our data also show that part of the ZU-5 motif is required for UNC-40-independent signaling of UNC-5.
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Affiliation(s)
- Marie Killeen
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada
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303
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Wills Z, Emerson M, Rusch J, Bikoff J, Baum B, Perrimon N, Van Vactor D. A Drosophila homolog of cyclase-associated proteins collaborates with the Abl tyrosine kinase to control midline axon pathfinding. Neuron 2002; 36:611-22. [PMID: 12441051 DOI: 10.1016/s0896-6273(02)01022-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We demonstrate that Drosophila capulet (capt), a homolog of the adenylyl cyclase-associated protein that binds and regulates actin in yeast, associates with Abl in Drosophila cells, suggesting a functional relationship in vivo. We find a robust and specific genetic interaction between capt and Abl at the midline choice point where the growth cone repellent Slit functions to restrict axon crossing. Genetic interactions between capt and slit support a model where Capt and Abl collaborate as part of the repellent response. Further support for this model is provided by genetic interactions that both capt and Abl display with multiple members of the Roundabout receptor family. These studies identify Capulet as part of an emerging pathway linking guidance signals to regulation of cytoskeletal dynamics and suggest that the Abl pathway mediates signals downstream of multiple Roundabout receptors.
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Affiliation(s)
- Zachary Wills
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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304
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Englund C, Steneberg P, Falileeva L, Xylourgidis N, Samakovlis C. Attractive and repulsive functions of Slit are mediated by different receptors in the Drosophila trachea. Development 2002; 129:4941-51. [PMID: 12397103 DOI: 10.1242/dev.129.21.4941] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Oxygen delivery in many animals is enabled by the formation of unicellular capillary tubes that penetrate target tissues to facilitate gas exchange. We show that the tortuous outgrowth of tracheal unicellular branches towards their target tissues is controlled by complex local interactions with target cells. Slit, a phylogenetically conserved axonal guidance signal, is expressed in several tracheal targets and is required both for attraction and repulsion of tracheal branches. Robo and Robo2 are expressed in different branches, and are both necessary for the correct orientation of branch outgrowth. At the CNS midline, Slit functions as a repellent for tracheal branches and this function is mediated primarily by Robo. Robo2 is necessary for the tracheal response to the attractive Slit signal and its function is antagonized by Robo. We propose that the attractive and repulsive tracheal responses to Slit are mediated by different combinations of Robo and Robo2 receptors on the cell surface.
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Affiliation(s)
- Camilla Englund
- Umeå Centre for Molecular Pathogenesis, Umeå University, Sweden
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305
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Yu TW, Hao JC, Lim W, Tessier-Lavigne M, Bargmann CI. Shared receptors in axon guidance: SAX-3/Robo signals via UNC-34/Enabled and a Netrin-independent UNC-40/DCC function. Nat Neurosci 2002; 5:1147-54. [PMID: 12379860 DOI: 10.1038/nn956] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2002] [Accepted: 11/09/2002] [Indexed: 11/09/2022]
Abstract
The C. elegans SAX-3/Robo receptor acts in anterior-posterior, dorsal-ventral and midline guidance decisions. Here we show that SAX-3 signaling involves the C. elegans Enabled protein UNC-34 and an unexpected Netrin-independent function of the Netrin receptor UNC-40/DCC. Genetic interactions with gain- and loss-of-function mutations suggest that unc-34 and unc-40 act together with sax-3 in several guidance decisions, but the C. elegans Netrin gene unc-6 does not act in the same genetic pathways. Within the migrating axon, sax-3, unc-34 and unc-40 all act cell-autonomously. Our results support a role for UNC-34/Enabled proteins in SAX-3-mediated repulsion, and show that UNC-40/DCC can potentiate SAX-3/Robo signaling via a mechanism that may involve direct binding of the two guidance receptors. A combinatorial logic dictates alternative functions for UNC-40/DCC, which can act in attraction to UNC-6/Netrin, repulsion from Netrin (with UNC-5), or repulsion from Slit (with SAX-3).
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Affiliation(s)
- Timothy W Yu
- Howard Hughes Medical Institute, Program in Neuroscience, Department of Anatomy and of Biochemistry and Biophysics, The University of California, San Francisco, California 94143, USA
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306
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Rhee J, Mahfooz NS, Arregui C, Lilien J, Balsamo J, VanBerkum MFA. Activation of the repulsive receptor Roundabout inhibits N-cadherin-mediated cell adhesion. Nat Cell Biol 2002; 4:798-805. [PMID: 12360290 DOI: 10.1038/ncb858] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Revised: 07/16/2002] [Accepted: 08/21/2002] [Indexed: 11/08/2022]
Abstract
The formation of axon trajectories requires integration of local adhesive interactions with directional information from attractive and repulsive cues. Here, we show that these two types of information are functionally integrated; activation of the transmembrane receptor Roundabout (Robo) by its ligand, the secreted repulsive guidance cue Slit, inactivates N-cadherin-mediated adhesion. Loss of N-cadherin-mediated adhesion is accompanied by tyrosine phosphorylation of beta-catenin and its loss from the N-cadherin complex, concomitant with the formation of a supramolecular complex containing Robo, Abelson (Abl) kinase and N-cadherin. Local formation of such a receptor complex is an ideal mechanism to steer the growth cone while still allowing adhesion and growth in other directions.
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Affiliation(s)
- Jinseol Rhee
- Department of Biological Sciences, The University of Iowa, Iowa City, IA 52242, USA
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307
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308
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Kim YS, Fritz JL, Seneviratne AK, VanBerkum MFA. Constitutively active myosin light chain kinase alters axon guidance decisions in Drosophila embryos. Dev Biol 2002; 249:367-81. [PMID: 12221012 DOI: 10.1006/dbio.2002.0768] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Conventional myosin II activity provides the motile force for axon outgrowth, but to achieve directional movement during axon pathway formation, myosin activity should be regulated by the attractive and repulsive guidance cues that guide an axon to its target. Here, evidence for this regulation is obtained by using a constitutively active Myosin Light Chain Kinase (ctMLCK) to selectively elevate myosin II activity in Drosophila CNS neurons. Expression of ctMLCK pan-neurally or in primarily pCC/MP2 neurons causes these axons to cross the midline incorrectly. This occurs without altering cell fates and is sensitive to mutations in the regulatory light chains. These results confirm the importance of regulating myosin II activity during axon pathway formation. Mutations in the midline repulsive ligand Slit, or its receptor Roundabout, enhance the number of ctMLCK-induced crossovers, but ctMLCK expression also partially rescues commissure formation in commissureless mutants, where repulsive signals remain high. Overexpression of Frazzled, the receptor for midline attractive Netrins, enhances ctMLCK-dependent crossovers, but crossovers are suppressed when Frazzled activity is reduced by using loss-of-function mutations. These results confirm that proper pathway formation requires careful regulation of MLCK and/or myosin II activity and suggest that regulation occurs in direct response to attractive and repulsive cues.
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Affiliation(s)
- You-Seung Kim
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA
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309
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Abstract
The receptor Roundabout-1 (Robo1) and its ligand Slit are known to influence axon guidance and central nervous system (CNS) patterning in both vertebrate and nonvertebrate systems. Although Robo-Slit interactions mediate axon guidance in the Drosophila CNS, their role in establishing the early axon scaffold in the embryonic vertebrate brain remains unclear. We report here the identification and expression of a Xenopus Robo1 orthologue that is highly homologous to mammalian Robo1. By using overexpression studies and immunohistochemical and in situ hybridization techniques, we have investigated the role of Robo1 in the development of a subset of neurons and axon tracts in the Xenopus forebrain. Robo1 is expressed in forebrain nuclei and in neuroepithelial cells underlying the main axon tracts. Misexpression of Robo1 led to aberrant development of axon tracts as well as the ectopic differentiation of forebrain neurons. These results implicate Robo1 in both neuronal differentiation and axon guidance in embryonic vertebrate forebrain.
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Affiliation(s)
- R M Connor
- Department of Anatomy and Developmental Biology, School of Biomedical Sciences, University of Queensland, Brisbane 4072, Australia
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310
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Abstract
Our understanding of neuronal migration has been advanced by multidisciplinary approaches. At the cellular level, tangential and radial modes of neuronal migration contribute to different populations of neurons and have differential dependence on glial cells. At the molecular level, extracellular guidance cues have been identified and intracellular signal transduction pathways are beginning to be revealed. Interestingly, mechanisms guiding axon projection and neuronal migration appear to be conserved with those for chemotactic leukocytes.
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Affiliation(s)
- Hwan Tae Park
- Department of Pediatrics, and Molecular Biology and Pharmacology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110
| | - Jane Wu
- Department of Pediatrics, and Molecular Biology and Pharmacology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110
- *Correspondence to: Jane Wu, Department of Pediatrics, and Molecular Biology and Pharmacology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110. E-mail: . Yi Rao, Department of Anatomy and Neurobiology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110. E-mail:
| | - Yi Rao
- Department of Anatomy and Neurobiology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110
- *Correspondence to: Jane Wu, Department of Pediatrics, and Molecular Biology and Pharmacology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110. E-mail: . Yi Rao, Department of Anatomy and Neurobiology, Box 8108, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110. E-mail:
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311
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Sasaki Y, Cheng C, Uchida Y, Nakajima O, Ohshima T, Yagi T, Taniguchi M, Nakayama T, Kishida R, Kudo Y, Ohno S, Nakamura F, Goshima Y. Fyn and Cdk5 mediate semaphorin-3A signaling, which is involved in regulation of dendrite orientation in cerebral cortex. Neuron 2002; 35:907-20. [PMID: 12372285 DOI: 10.1016/s0896-6273(02)00857-7] [Citation(s) in RCA: 273] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Semaphorin-3A (Sema3A), a member of class 3 semaphorins, regulates axon and dendrite guidance in the nervous system. How Sema3A and its receptors plexin-As and neuropilins regulate neuronal guidance is unknown. We observed that in fyn- and cdk5-deficient mice, Sema3A-induced growth cone collapse responses were attenuated compared to their heterologous controls. Cdk5 is associated with plexin-A2 through the active state of Fyn. Sema3A promotes Cdk5 activity through phosphorylation of Tyr15, a phosphorylation site with Fyn. A Cdk5 mutant (Tyr15 to Ala) shows a dominant-negative effect on the Sema3A-induced collapse response. The sema3A gene shows strong interaction with fyn for apical dendrite guidance in the cerebral cortex. We propose a signal transduction pathway in which Fyn and Cdk5 mediate neuronal guidance regulated by Sema3A.
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Affiliation(s)
- Yukio Sasaki
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University School of Medicine, Yokohama, Japan.
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312
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Myat A, Henry P, McCabe V, Flintoft L, Rotin D, Tear G. Drosophila Nedd4, a ubiquitin ligase, is recruited by Commissureless to control cell surface levels of the roundabout receptor. Neuron 2002; 35:447-59. [PMID: 12165468 DOI: 10.1016/s0896-6273(02)00795-x] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Crossing the midline produces changes in axons such that they are no longer attracted to the midline. In Drosophila, Roundabout reaches high levels on axons once they have crossed the midline, and this prohibits recrossing. Roundabout protein levels are regulated by Commissureless. We show that Commissureless binds to and is regulated by the ubiquitin ligase DNedd4. We further show that the ability of Commissureless to regulate Roundabout protein levels requires an intact DNedd4 binding site and ubiquitin acceptor sites within the Commissureless protein. The ability of Commissureless to regulate Robo in the embryo also requires a Commissureless/DNedd4 interaction. Our results show that changes in axonal sensitivity to external cues during pathfinding across the midline makes use of ubiquitin-dependent mechanisms to regulate transmembrane protein levels.
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Affiliation(s)
- Anna Myat
- Molecular Neurobiology Group, MRC Centre for Developmental Neurobiology, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom
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313
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Abstract
A majority of neurons that form the ventral nerve cord send out long axons that cross the midline through anterior or posterior commissures. A smaller fraction extend longitudinally and never cross the midline. The decision to cross the midline is governed by a balance of attractive and repulsive signals. We have explored the role of a G-protein, Galphaq, in altering this balance in Drosophila. A splice variant of Galphaq, dgqalpha3, is expressed in early axonal growth cones, which go to form the commissures in the Drosophila embryonic CNS. Misexpression of a gain-of-function transgene of dgqalpha3 (AcGq3) leads to ectopic midline crossing. Analysis of the AcGq3 phenotype in roundabout and frazzled mutants shows that AcGq3 function is antagonistic to Robo signaling and requires Frazzled to promote ectopic midline crossing. Our results show for the first time that a heterotrimeric G-protein can affect the balance of attractive versus repulsive cues in the growth cone and that it can function as a component of signaling pathways that regulate axonal pathfinding.
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314
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Loureiro JJ, Rubinson DA, Bear JE, Baltus GA, Kwiatkowski AV, Gertler FB. Critical roles of phosphorylation and actin binding motifs, but not the central proline-rich region, for Ena/vasodilator-stimulated phosphoprotein (VASP) function during cell migration. Mol Biol Cell 2002; 13:2533-46. [PMID: 12134088 PMCID: PMC117332 DOI: 10.1091/mbc.e01-10-0102] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Ena/vasodilator-stimulated phosphoprotein (VASP) protein family is implicated in the regulation of a number of actin-based cellular processes, including lamellipodial protrusion necessary for whole cell translocation. A growing body of evidence derived largely from in vitro biochemical experiments using purified proteins, cell-free extracts, and pathogen motility has begun to suggest various mechanistic roles for Ena/VASP proteins in the control of actin dynamics. Using complementation of phenotypes in Ena/VASP-deficient cells and overexpression in normal fibroblasts, we have assayed the function of a panel of mutants in one member of this family, Mena, by mutating highly conserved sequence elements found in this protein family. Surprisingly, deletion of sites required for binding of the actin monomer-binding protein profilin, a known ligand of Ena/VASP proteins, has no effect on the ability of Mena to regulate random cell motility. Our analysis revealed two features essential for Ena/VASP function in cell movement, cyclic nucleotide-dependent kinase phosphorylation sites and an F-actin binding motif. Interestingly, expression of the C-terminal EVH2 domain alone is sufficient to complement loss of Ena/VASP function in random cell motility.
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Affiliation(s)
- Joseph J Loureiro
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
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315
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Sabo SL, Ikin AF. Cytosolic protein-protein interactions that regulate the amyloid precursor protein. Drug Dev Res 2002. [DOI: 10.1002/ddr.10078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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316
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Huang X, Cheng HJ, Tessier-Lavigne M, Jin Y. MAX-1, a novel PH/MyTH4/FERM domain cytoplasmic protein implicated in netrin-mediated axon repulsion. Neuron 2002; 34:563-76. [PMID: 12062040 DOI: 10.1016/s0896-6273(02)00672-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The netrin UNC-6 repels motor axons by activating the UNC-5 receptor alone or in combination with the UNC-40/DCC receptor. In a genetic screen for C. elegans mutants exhibiting partial defects in motor axon projections, we isolated the max-1 gene (required for motor neuron axon guidance). max-1 loss-of-function mutations cause fully penetrant but variable axon guidance defects. Mutations in unc-5 and unc-6, but not in unc-40, dominantly enhance the mutant phenotypes of max-1, whereas overexpression of unc-5 or unc-6, but not of unc-40, bypasses the requirement for max-1. MAX-1 proteins contain PH, MyTH4, and FERM domains and appear to be localized to neuronal processes. Human MAX-1 and UNC5H2 colocalize in discrete subcellular regions of transfected cells. Our results suggest a possible role for MAX-1 in netrin-induced axon repulsion by modulating the UNC-5 receptor signaling pathway.
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Affiliation(s)
- Xun Huang
- Department of Molecular, Cellular, and Developmental Biology, Santa Cruz, CA 95064, USA
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317
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Dallol A, Forgacs E, Martinez A, Sekido Y, Walker R, Kishida T, Rabbitts P, Maher ER, Minna JD, Latif F. Tumour specific promoter region methylation of the human homologue of the Drosophila Roundabout gene DUTT1 (ROBO1) in human cancers. Oncogene 2002; 21:3020-8. [PMID: 12082532 DOI: 10.1038/sj.onc.1205421] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2001] [Revised: 02/01/2002] [Accepted: 02/19/2002] [Indexed: 11/08/2022]
Abstract
The human homologue of the Drosophila Roundabout gene DUTT1 (Deleted in U Twenty Twenty) or ROBO1 (Locus Link ID 6091), a member of the NCAM family of receptors, was recently cloned from the lung cancer tumour suppressor gene region 2 (LCTSGR2 or U2020 region) at 3p12. DUTT1 maps within a region of overlapping homozygous deletions characterized in both small cell lung cancer lines (SCLC) and in a breast cancer line. In this report we (a) defined the genomic organization of the DUTT1 gene, (b) performed mutation and expression analysis of DUTT1 in lung, breast and kidney cancers, (c) identified tumour specific promoter region methylation of DUTT1 in human cancers. The gene was found to contain 29 exons and spans at least 240 kb of genomic sequence. The 5' region contains a CpG island, and the poly(A)(+) tail has an atypical 5'-GATAAA-3' signal. We analysed DUTT1 for mutations in lung, breast and kidney cancers, no inactivating mutations were detected by PCR-SSCP. However, seven germline missense changes were found and characterized. DUTT1 expression was not detectable in one out of 18 breast tumour lines analysed by RT-PCR. Bisulfite sequencing of the promoter region of DUTT1 gene in the HTB-19 breast tumour cell line (not expressing DUTT1) showed complete hypermethylation of CpG sites within the promoter region of the DUTT1 gene (-244 to +27 relative to the translation start site). The expression of DUTT1 gene was reactivated in HTB-19 after treatment with the demethylating agent 5-aza-2'-deoxycytidine. The same region was also found to be hypermethylated in six out of 32 (19%) primary invasive breast carcinomas and eight out of 44 (18%) primary clear cell renal cell carcinomas (CC-RCC) and in one out of 26 (4%) primary NSCLC tumours. Furthermore 80% of breast and 75% of CC-RCC tumours showing DUTT1 methylation had allelic losses for 3p12 markers hence obeying Knudson's two hit hypothesis. Our findings suggest that DUTT1 warrants further analysis as a candidate for the tumour suppressor gene (TSG) at 3p12, a region defined by hemi and homozygous deletions and functional analysis.
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MESH Headings
- Animals
- Azacitidine/analogs & derivatives
- Azacitidine/pharmacology
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Carcinoma/genetics
- Carcinoma/pathology
- Carcinoma, Non-Small-Cell Lung/genetics
- Carcinoma, Non-Small-Cell Lung/pathology
- Chromosomes, Human, Pair 3/genetics
- CpG Islands
- DNA Methylation
- DNA Mutational Analysis
- DNA, Neoplasm/genetics
- Decitabine
- Drosophila Proteins/genetics
- Drosophila melanogaster/genetics
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- Genes, Tumor Suppressor
- Humans
- Kidney Neoplasms/genetics
- Kidney Neoplasms/pathology
- Loss of Heterozygosity
- Lung Neoplasms/genetics
- Lung Neoplasms/pathology
- Mutation, Missense
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/physiology
- Promoter Regions, Genetic/genetics
- Receptors, Immunologic
- Sequence Homology, Nucleic Acid
- Tumor Cells, Cultured
- Roundabout Proteins
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Affiliation(s)
- Ashraf Dallol
- Section of Medical and Molecular Genetics, Department of Paediatrics and Child Health, University of Birmingham, The Medical School, Edgbaston, Birmingham B15 2TT, UK.
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318
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Abstract
Neuronal migration requires the integration of a number of diverse environmental cues and subsequent translation to specific responses such as directed cytoskeletal remodeling. Accurate knowledge of the signal transduction pathways linking activation of surface receptors to actin dynamics is necessary in order to understand the regulation of such processes. Activation of the Roundabout (Robo) receptor mediates a repulsive response in certain pioneering axons and migratory neurons. Recently, Wong et al have described a signaling link between Robo activation and specific GTPase activity that appears to regulate neuronal migration. A novel family of GTPase regulators, responsive to Slit-Robo engagement, has been identified and convincingly shown to alter the migration of neuronal cells. This study not only delineates a specific signaling route from guidance receptors to directed neuronal movement, but also offers clues towards potential regulatory mechanisms that ensure specificity of the Slit-Robo response.
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Affiliation(s)
- Aurnab Ghose
- Department of Cell Biology, Program in Neuroscience and DFCI/Harvard Cancer Center, Harvard Medical School, Boston, MA 02115, USA
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319
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Ectopic expression in the giant fiber system of Drosophila reveals distinct roles for roundabout (Robo), Robo2, and Robo3 in dendritic guidance and synaptic connectivity. J Neurosci 2002. [PMID: 11943815 DOI: 10.1523/jneurosci.22-08-03117.2002] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Roundabout (Robo) receptors have been intensively studied for their role in regulating axon guidance in the embryonic nervous system, whereas a role in dendritic guidance has not been explored. In the adult giant fiber system of Drosophila, we have revealed that ectopic Robo expression can regulate the growth and guidance of specific motor neuron dendrites, whereas Robo2 and Robo3 have no effect. We also show that the effect of Robo on dendritic guidance can be suppressed by Commissureless coexpression. Although we confirmed a role for all three Robo receptors in giant fiber axon guidance, the strong axon guidance alterations caused by overexpression of Robo2 or Robo3 have no effect on synaptic connectivity. In contrast, Robo overexpression in the giant fiber seems to directly interfere with synaptic function. We conclude that axon guidance, dendritic guidance, and synaptogenesis are separable processes and that the different Robo family members affect them distinctly.
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320
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Shyamala BV, Bhat KM. A positive role for Patched-Smoothened signaling in promoting cell proliferation during normal head development in Drosophila. Development 2002; 129:1839-47. [PMID: 11934850 DOI: 10.1242/dev.129.8.1839] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The transmembrane receptor Patched regulates several developmental processes in both invertebrates and vertebrates. In vertebrates, Patched also acts as a tumor suppressor. The Patched pathway normally operates by negatively regulating Smoothened, a G-protein-coupled receptor; binding of Hedgehog ligand to Patched relieves this negative interaction and allows signaling by Smoothened. We show that Ptc regulates Drosophila head development by promoting cell proliferation in the eye-antennal disc. During head morphogenesis, Patched positively interacts with Smoothened, which leads to the activation of Activin type I receptor Baboon and stimulation of cell proliferation in the eye-antennal disc. Thus, loss of Ptc or Smoothened activity affects cell proliferation in the eye-antennal disc and results in adult head capsule defects. Similarly, reducing the dose of smoothened in a patched background enhances the head defects. Consistent with these results, gain-of-function Hedgehog interferes with the activation of Baboon by Patched and Smoothened, leading to a similar head capsule defect. Expression of an activated form of Baboon in the patched domain in a patched mutant background completely rescues the head defects. These results provide insight into head morphogenesis, a process we know very little about, and reveal an unexpected non-canonical positive signaling pathway in which Patched and Smoothened function to promote cell proliferation as opposed to repressing it.
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Affiliation(s)
- Baragur V Shyamala
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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321
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Huminiecki L, Gorn M, Suchting S, Poulsom R, Bicknell R. Magic roundabout is a new member of the roundabout receptor family that is endothelial specific and expressed at sites of active angiogenesis. Genomics 2002; 79:547-52. [PMID: 11944987 DOI: 10.1006/geno.2002.6745] [Citation(s) in RCA: 258] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have used bioinformatic data mining to identify a novel, endothelial-specific gene encoding a protein with homology to the axon guidance protein roundabout (ROBO1). The new gene has been called magic roundabout (ROBO4; GenBank acc. no. AF361473) and is smaller than other members of the roundabout gene family. Thus, in the extracellular region, magic roundabout has only two of the five immunoglobulin and two of the three fibronectin domains present in other roundabout genes. Expression of magic roundabout in vitro was detected in only endothelial cells and was greater in cells exposed to hypoxia. In situ hybridization and immunohistochemistry validated the bioinformatic prediction that magic roundabout expression would be endothelial specific in vivo. Magic roundabout expression in the adult was restricted exclusively to sites of active angiogenesis, notably tumor vessels. The identification of magic roundabout shows that the roundabout gene family extends beyond neuronal tissue and that roundabout/slit interactions are likely to have a role in angiogenesis.
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Affiliation(s)
- Lukasz Huminiecki
- Molecular Angiogenesis Laboratory, Cancer Research UK, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
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322
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Abstract
Recent advances in the study of axon guidance have begun to clarify the intricate signalling mechanisms utilised by receptors that mediate path-finding. Many of these axon guidance receptors, including Plexin B, EphA, ephrin B and Robo, regulate the Rho family of GTPases, to effect changes in motility. Recent studies demonstrate a critical role for the cytoplasmic tails of guidance receptors in signalling and also reveal the potential for a great deal of crosstalk between the various receptor-signalling pathways.
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Affiliation(s)
- Bharatkumar N Patel
- Program in Neuroscience, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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323
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Woodring PJ, Litwack ED, O'Leary DDM, Lucero GR, Wang JYJ, Hunter T. Modulation of the F-actin cytoskeleton by c-Abl tyrosine kinase in cell spreading and neurite extension. J Cell Biol 2002; 156:879-92. [PMID: 11864995 PMCID: PMC2173320 DOI: 10.1083/jcb.200110014] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The nonreceptor tyrosine kinase encoded by the c-Abl gene has the unique feature of an F-actin binding domain (FABD). Purified c-Abl tyrosine kinase is inhibited by F-actin, and this inhibition can be relieved through mutation of its FABD. The c-Abl kinase is activated by physiological signals that also regulate the actin cytoskeleton. We show here that c-Abl stimulated the formation of actin microspikes in fibroblasts spreading on fibronectin. This function of c-Abl is dependent on kinase activity and is not shared by c-Src tyrosine kinase. The Abl-dependent F-actin microspikes occurred under conditions where the Rho-family GTPases were inhibited. The FABD-mutated c-Abl, which is active in detached fibroblasts, stimulated F-actin microspikes independent of cell attachment. Moreover, FABD-mutated c-Abl stimulated the formation of F-actin branches in neurites of rat embryonic cortical neurons. The reciprocal regulation between F-actin and the c-Abl tyrosine kinase may provide a self-limiting mechanism in the control of actin cytoskeleton dynamics.
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324
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Fischer DD, Cai R, Bhatia U, Asselbergs FAM, Song C, Terry R, Trogani N, Widmer R, Atadja P, Cohen D. Isolation and characterization of a novel class II histone deacetylase, HDAC10. J Biol Chem 2002; 277:6656-66. [PMID: 11739383 DOI: 10.1074/jbc.m108055200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel histone deacetylase, HDAC10, was isolated from a mixed tissue human cDNA library. HDAC10 was classified as a class II subfamily member based upon similarity to HDAC6. The genomic structure of HDAC10 was found to consist of 20 exons. HDAC10 has two sequence variants, HDAC10v1 and HDAC10v2, and two transcripts were detectable by Northern blot analysis. HDAC10v1 and HDAC10v2 were found to be identical through exon 17 but diverged after this exon. HDAC10v2 has an 82-bp alternate exon that generates a frameshift and shortens the sequence by 11 amino acids. In this study, the characterization of HDAC10v1 was performed. HDAC10v1 has an N-terminal catalytic domain, two putative C-terminal retinoblastoma protein binding domains, and a nuclear hormone receptor binding motif. The HDAC10v1 enzyme was found to be catalytically active based upon its ability to deacetylate a (3)H-acetylated histone H4 N-terminal peptide. Immunofluorescence detection of transfected HDAC10v1-FLAG indicated that the enzyme is a nuclear protein. Furthermore, coimmunoprecipitation experiments indicated that HDAC10v1 associated with HDAC2 and SMRT (silencing mediator for retinoid and thyroid hormone receptors). In addition, based upon the public data base, a single nucleotide polymorphism was found in the C terminus of HDAC10 which changes a Gly residue to Cys, suggesting that HDAC10 molecules containing these single nucleotide polymorphisms may be folded improperly. HDAC10 extends the HDAC superfamily and adds to a growing number of HDACs that have been found to have splice variants, suggesting that RNA processing may play a role in mediating the activity of HDACs.
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Affiliation(s)
- Denise D Fischer
- Department of Functional Genomics, Novartis Pharmaceuticals, Summit, New Jersey 07901, USA
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325
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Abstract
Drosophila enabled/vasodilator-stimulated phosphoprotein homology 1 (EVH1) domains are 115 residue protein-protein interaction modules which provide essential links for their host proteins to various signal transduction pathways. Many EVH1-containing proteins are associated closely with actin-based structures and are involved in re-organization of the actin cytoskeleton. EVH1 domains are also present in proteins enriched in neuronal tissue, thus implicating them as potential mediators of synaptic plasticity, linking them to memory formation and learning. Like Src homology 3, WW and GYF domains and profilin, EVH1 domains recognize and bind specific proline-rich sequences (PRSs). The binding is of low affinity, but tightly regulated by the high specificity encoded into residues in the protein:peptide interface. In general, a small (3-6 residue) 'core' PRS in the target protein binds a 'recognition pocket' on the domain surface. Further affinity- and specificity-increasing interactions are then formed between additional domain epitopes and peptide 'core-flanking' residues. The three-dimensional structures of EVH1:peptide complexes now reveal, in great detail, some of the most important features of these interactions and allow us to better understand the origins of specificity, ligand orientation and sequence degeneracy of target peptides, in low affinity signalling complexes.
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Affiliation(s)
- Linda J Ball
- Forschunginstitut für Molekulare Pharmacologie, Campus Berlin-Buch, Berlin, Germany.
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326
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Renfranz PJ, Beckerle MC. Doing (F/L)PPPPs: EVH1 domains and their proline-rich partners in cell polarity and migration. Curr Opin Cell Biol 2002; 14:88-103. [PMID: 11792550 DOI: 10.1016/s0955-0674(01)00299-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Actin filament assembly is a tightly regulated process that functions in many aspects of cell physiology. Members of the Ena/VASP (Drosophila Enabled/vasodilator-stimulated phosphoprotein) family are key players in regulating actin filament assembly, in many cases through their association with binding partners that display a particular proline-rich motif, FPPPP. Ena/VASP proteins interact with these partners via the highly conserved Ena/VASP homology 1 (EVH1) domain. The diverse array of binding partners for EVH1 domains, including cytoskeletal proteins such as zyxin, transmembrane guidance receptors such as Roundabout, and the T-cell signaling protein Fyb/SLAP, shows that these interactions are likely to be important in a number of cellular processes that require regulated actin filament assembly.
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Affiliation(s)
- Patricia J Renfranz
- Department of Biology and Huntsman Cancer Institute, 2000 East Circle of Hope, University of Utah, Salt Lake City, UT 84112-5550, USA
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327
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Whitford KL, Marillat V, Stein E, Goodman CS, Tessier-Lavigne M, Chédotal A, Ghosh A. Regulation of cortical dendrite development by Slit-Robo interactions. Neuron 2002; 33:47-61. [PMID: 11779479 DOI: 10.1016/s0896-6273(01)00566-9] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Slit proteins have previously been shown to regulate axon guidance, branching, and neural migration. Here we report that, in addition to acting as a chemorepellant for cortical axons, Slit1 regulates dendritic development. Slit1 is expressed in the developing cortex, and exposure to Slit1 leads to increased dendritic growth and branching. Conversely, inhibition of Slit-Robo interactions by Robo-Fc fusion proteins or by a dominant-negative Robo attenuates dendritic branching. Stimulation of neurons transfected with a Met-Robo chimeric receptor with Hepatocyte growth factor leads to a robust induction of dendritic growth and branching, suggesting that Robo-mediated signaling is sufficient to induce dendritic remodeling. These experiments indicate that Slit-Robo interactions may exert a significant influence over the specification of cortical neuron morphology by regulating both axon guidance and dendritic patterning.
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Affiliation(s)
- Kristin L Whitford
- Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
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328
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Grevengoed EE, Loureiro JJ, Jesse TL, Peifer M. Abelson kinase regulates epithelial morphogenesis in Drosophila. J Cell Biol 2001; 155:1185-98. [PMID: 11756472 PMCID: PMC2199330 DOI: 10.1083/jcb.200105102] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2001] [Revised: 11/05/2001] [Accepted: 11/06/2001] [Indexed: 11/22/2022] Open
Abstract
Activation of the nonreceptor tyrosine kinase Abelson (Abl) contributes to the development of leukemia, but the complex roles of Abl in normal development are not fully understood. Drosophila Abl links neural axon guidance receptors to the cytoskeleton. Here we report a novel role for Drosophila Abl in epithelial cells, where it is critical for morphogenesis. Embryos completely lacking both maternal and zygotic Abl die with defects in several morphogenetic processes requiring cell shape changes and cell migration. We describe the cellular defects that underlie these problems, focusing on dorsal closure as an example. Further, we show that the Abl target Enabled (Ena), a modulator of actin dynamics, is involved with Abl in morphogenesis. We find that Ena localizes to adherens junctions of most epithelial cells, and that it genetically interacts with the adherens junction protein Armadillo (Arm) during morphogenesis. The defects of abl mutants are strongly enhanced by heterozygosity for shotgun, which encodes DE-cadherin. Finally, loss of Abl reduces Arm and alpha-catenin accumulation in adherens junctions, while having little or no effect on other components of the cytoskeleton or cell polarity machinery. We discuss possible models for Abl function during epithelial morphogenesis in light of these data.
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Affiliation(s)
- E E Grevengoed
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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329
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Bashaw GJ, Hu H, Nobes CD, Goodman CS. A novel Dbl family RhoGEF promotes Rho-dependent axon attraction to the central nervous system midline in Drosophila and overcomes Robo repulsion. J Cell Biol 2001; 155:1117-22. [PMID: 11756465 PMCID: PMC2199320 DOI: 10.1083/jcb.200110077] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The key role of the Rho family GTPases Rac, Rho, and CDC42 in regulating the actin cytoskeleton is well established (Hall, A. 1998. Science. 279:509-514). Increasing evidence suggests that the Rho GTPases and their upstream positive regulators, guanine nucleotide exchange factors (GEFs), also play important roles in the control of growth cone guidance in the developing nervous system (Luo, L. 2000. Nat. Rev. Neurosci. 1:173-180; Dickson, B.J. 2001. Curr. Opin. Neurobiol. 11:103-110). Here, we present the identification and molecular characterization of a novel Dbl family Rho GEF, GEF64C, that promotes axon attraction to the central nervous system midline in the embryonic Drosophila nervous system. In sensitized genetic backgrounds, loss of GEF64C function causes a phenotype where too few axons cross the midline. In contrast, ectopic expression of GEF64C throughout the nervous system results in a phenotype in which far too many axons cross the midline, a phenotype reminiscent of loss of function mutations in the Roundabout (Robo) repulsive guidance receptor. Genetic analysis indicates that GEF64C expression can in fact overcome Robo repulsion. Surprisingly, evidence from genetic, biochemical, and cell culture experiments suggests that the promotion of axon attraction by GEF64C is dependent on the activation of Rho, but not Rac or Cdc42.
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Affiliation(s)
- G J Bashaw
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104, USA.
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330
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Calderwood DA, Huttenlocher A, Kiosses WB, Rose DM, Woodside DG, Schwartz MA, Ginsberg MH. Increased filamin binding to beta-integrin cytoplasmic domains inhibits cell migration. Nat Cell Biol 2001; 3:1060-8. [PMID: 11781567 DOI: 10.1038/ncb1201-1060] [Citation(s) in RCA: 182] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Multicellular animal development depends on integrins. These adhesion receptors link to the actin cytoskeleton, transmitting biochemical signals and force during cell migration and interactions with the extracellular matrix. Many integrin-cytoskeleton connections are formed by filamins and talin. The beta7 integrin tail binds strongly to filamin and supports less migration, fibronectin matrix assembly and focal adhesion formation than either the beta1D tail, which binds strongly to talin, or the beta1A tail, which binds modestly to both filamin and talin. To probe the role of filamin binding, we mapped the filamin-binding site of integrin tails and identified amino acid substitutions that led to selective loss of filamin binding to the beta7 tail and gain of filamin binding to the beta1A tail. These changes affected cell migration and membrane protrusions but not fibronectin matrix assembly or focal adhesion formation. Thus, tight filamin binding restricts integrin-dependent cell migration by inhibiting transient membrane protrusion and cell polarization.
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Affiliation(s)
- D A Calderwood
- Department of Vascular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, California 92037, USA
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331
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Tong J, Killeen M, Steven R, Binns KL, Culotti J, Pawson T. Netrin stimulates tyrosine phosphorylation of the UNC-5 family of netrin receptors and induces Shp2 binding to the RCM cytodomain. J Biol Chem 2001; 276:40917-25. [PMID: 11533026 DOI: 10.1074/jbc.m103872200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Caenorhabditis elegans UNC-5 and its mammalian homologues such as RCM are receptors for the secreted axon guidance cue UNC-6/netrin and are required to mediate the repulsive effects of UNC-6/netrin on growth cones. We find that C. elegans UNC-5 and mouse RCM are phosphorylated on tyrosine in vivo. C. elegans UNC-5 tyrosine phosphorylation is reduced in unc-6 null mutants, and RCM tyrosine phosphorylation is induced by netrin-1 in transfected HEK-293 cells, demonstrating that phosphorylation of UNC-5 proteins is enhanced by UNC-6/netrin stimulation in both worms and mammalian cells. An activated Src tyrosine kinase induces phosphorylation of RCM at multiple cytoplasmic tyrosine residues creating potential binding sites for cytoplasmic signaling proteins. Indeed, the NH2-terminal SH2 domain of the Shp2 tyrosine phosphatase bound specifically to a Tyr(568) RCM phosphopeptide. Furthermore, Shp2 associated with RCM in a netrin-dependent manner in transfected cells, and co-immunoprecipitated with RCM from an embryonic mouse brain lysate. A Y568F mutant RCM receptor failed to bind Shp2 and was more highly phosphorylated on tyrosine than the wild type receptor. These results suggest that netrin-stimulated phosphorylation of RCM Tyr(568) recruits Shp2 to the cell membrane where it can potentially modify RCM phosphorylation and function.
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Affiliation(s)
- J Tong
- Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
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332
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Abstract
To reach their proper targets, axons rely upon the actions of highly conserved families of attractive and repulsive guidance molecules, including the netrins, Slits, semaphorins and ephrins. These guidance systems are used to generate an astonishingly varied set of neuronal circuits. Here we consider the mechanisms by which a few guidance systems can be used to generate diverse outcomes. Recent studies have revealed extensive transcriptional and post-transcriptional regulation of guidance cues and their receptors, as well as combinatorial mechanisms that integrate information from different families of guidance cues.
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Affiliation(s)
- T W Yu
- Howard Hughes Medical Institute, Program in Neuroscience, Department of Anatomy, University of California, San Francisco, California 94143, USA
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333
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Abstract
The semaphorins are a family of secreted, transmembrane, and membrane-associated proteins initially identified as causing the repulsion of nerve growth cone guidance. However, subsequent experiments have demonstrated that they can induce retraction in non-neural cells and affect the development of non-neural organs. Two related secreted semaphorins, SEMA3F and SEMA3B, were isolated from a recurrent 3p21.3 homozygous deletion region in small-cell lung cancer (SCLC) cell lines. Moreover, a functionally related molecule, Roundabout/DUTT1, was identified as the target of a more proximal chromosome 3p deletion also involving SCLCs. Based on current data, it is likely that the loss of these semaphorins or Roundabout may affect cell migration, metastasis, and apoptosis. In addition, receptors for the secreted semaphorins, neuropilin-1 and neuropilin-2, have been shown to function as coreceptors for a subset of vascular endothelial growth factor (VEGF) isoforms and related growth factors. Since semaphorins and VEGF bind antagonistically to neuropilins, their loss is likely to facilitate angiogenesis. In lung cancer specimens, antibody staining against SEMA3F has been shown to correlate with stage and histologic subtypes with more aggressive tumors showing increased VEGF and decreased SEMA3F staining. This review is focused on a basic understanding of these pathways with an emphasis on their role in lung cancer.
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Affiliation(s)
- J Roche
- Institut de Biologie Moleculaire et d'Ingénierie Génétique, CNRS FRE 2224, Université de Poitiers, France
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334
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Koretzky GA, Myung PS. Positive and negative regulation of T-cell activation by adaptor proteins. Nat Rev Immunol 2001; 1:95-107. [PMID: 11905825 DOI: 10.1038/35100523] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adaptor proteins, molecules that mediate intermolecular interactions, are now known to be as crucial for lymphocyte activation as are receptors and effectors. Extensive work from numerous laboratories has identified and characterized many of these adaptors, demonstrating their roles as both positive and negative regulators. Studies into the molecular basis for the actions of these molecules shows that they function in various ways, including: recruitment of positive or negative regulators into signalling networks, modulation of effector function by allosteric regulation of enzymatic activity, and by targeting other proteins for degradation. This review will focus on a number of adaptors that are important for lymphocyte function and emphasize the various ways in which these proteins carry out their essential roles.
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Affiliation(s)
- G A Koretzky
- Abramson Family Cancer Research Institute and Department of Pathology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
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335
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Wong K, Ren XR, Huang YZ, Xie Y, Liu G, Saito H, Tang H, Wen L, Brady-Kalnay SM, Mei L, Wu JY, Xiong WC, Rao Y. Signal transduction in neuronal migration: roles of GTPase activating proteins and the small GTPase Cdc42 in the Slit-Robo pathway. Cell 2001; 107:209-21. [PMID: 11672528 DOI: 10.1016/s0092-8674(01)00530-x] [Citation(s) in RCA: 431] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Slit protein guides neuronal and leukocyte migration through the transmembrane receptor Roundabout (Robo). We report here that the intracellular domain of Robo interacts with a novel family of Rho GTPase activating proteins (GAPs). Two of the Slit-Robo GAPs (srGAPs) are expressed in regions responsive to Slit. Slit increased srGAP1-Robo1 interaction and inactivated Cdc42. A dominant negative srGAP1 blocked Slit inactivation of Cdc42 and Slit repulsion of migratory cells from the anterior subventricular zone (SVZa) of the forebrain. A constitutively active Cdc42 blocked the repulsive effect of Slit. These results have demonstrated important roles for GAPs and Cdc42 in neuronal migration. We propose a signal transduction pathway from the extracellular guidance cue to intracellular actin polymerization.
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Affiliation(s)
- K Wong
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO 63110, USA
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336
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Castellano F, Le Clainche C, Patin D, Carlier MF, Chavrier P. A WASp-VASP complex regulates actin polymerization at the plasma membrane. EMBO J 2001; 20:5603-14. [PMID: 11598004 PMCID: PMC125672 DOI: 10.1093/emboj/20.20.5603] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Proteins of the Wiskott-Aldrich syndrome and Ena/VASP families both play essential functions in the regulation of actin dynamics at the cell leading edge. However, possibilities of functional interplay between members of these two families have not been addressed. Here we show that, in hemopoietic cells, recruitment of the C-terminal VCA (Verprolin homology, Cofilin homology, Acidic) domain of WASp at the plasma membrane by a ligand technique using rapamycin as an intermediate is not sufficient to elicit efficient Arp2/3 complex-mediated actin polymerization. Other domains of WASp, in particular the proline-rich domain, are required for the formation of actin-rich structures. An in vitro analysis demonstrates that the proline-rich domain of WASp binds VASP with an affinity of approximately 10(6) M(-1). In addition, WASp and VASP both accumulate in actin-rich phagocytic cups. Finally, in a reconstituted motility medium, VASP enhances actin-based propulsion of WASp-coated beads in a fashion reminiscent of its effect on Listeria movement. We propose that VASP and WASp cooperation is essential in stimulating actin assembly and membrane protrusion at the leading edge.
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Affiliation(s)
| | - Christophe Le Clainche
- Laboratoire de la Dynamique de la Membrane et du Cytosquelette, Centre National de la Recherche Scientifique UMR 144, Institut Curie, 26 rue d’Ulm, 75241 Paris Cedex 5 and
Laboratoire d’Enzymologie et Biochimie Structurale, CNRS, 91198 Gif-sur-Yvette, France Corresponding author e-mail:
| | | | - Marie-France Carlier
- Laboratoire de la Dynamique de la Membrane et du Cytosquelette, Centre National de la Recherche Scientifique UMR 144, Institut Curie, 26 rue d’Ulm, 75241 Paris Cedex 5 and
Laboratoire d’Enzymologie et Biochimie Structurale, CNRS, 91198 Gif-sur-Yvette, France Corresponding author e-mail:
| | - Philippe Chavrier
- Laboratoire de la Dynamique de la Membrane et du Cytosquelette, Centre National de la Recherche Scientifique UMR 144, Institut Curie, 26 rue d’Ulm, 75241 Paris Cedex 5 and
Laboratoire d’Enzymologie et Biochimie Structurale, CNRS, 91198 Gif-sur-Yvette, France Corresponding author e-mail:
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337
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Brümmendorf T, Lemmon V. Immunoglobulin superfamily receptors: cis-interactions, intracellular adapters and alternative splicing regulate adhesion. Curr Opin Cell Biol 2001; 13:611-8. [PMID: 11544031 DOI: 10.1016/s0955-0674(00)00259-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The immunoglobulin domain is a module found in vertebrates and invertebrates. Its ability to form linear rods when deployed in series, combined with its propensity to bind specifically to other proteins has made it ideal for building cell surface receptors and cell adhesion molecules. These features have resulted in the incorporation of immunoglobulin domains into many hundreds of cell surface molecules. Recently three major advances have been made in understanding immunoglobulin receptors. One is the recognition that their intracellular binding partners are likely to link to multiple cell surface molecules, allowing cross-talk or oligomeric complex formation. A second, but related phenomenon, is their participation in cis-interactions on the extracellular surface that regulate signaling or adhesion. The third is the dramatic ability to form dozens to thousands of different isoforms via alternative splicing. Although antibodies may have been the first example of immunoglobulin-domain-containing proteins using cis-interactions to form receptor like molecules, and the grandest instance of diversity production from limited genetic material, these are clearly old ideas in this superfamily.
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Affiliation(s)
- T Brümmendorf
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Strasse 10, D-13092 Berlin, Germany.
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338
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Abstract
The developmental steps required to build a brain have been recognized as a distinctive sequence since the turn of the twentieth century. As marking tools for experimental embryology emerged, the cellular events of cortical histogenesis have been intensively scrutinized. On this rich backdrop, molecular genetics provides the opportunity to play out the molecular programs that orchestrate these cellular events. Genetic studies of human brain malformation have proven a surprising source for finding the molecules that regulate CNS neuronal migration. These studies also serve to relate the significance of genes first identified in murine species to the more complex human brain. The known genetic repertoire that is special to neuronal migration in brain has rapidly expanded over the past five years, making this an appropriate time to take stock of the emerging picture. We do this from the perspective of human brain malformation syndromes, noting both what is now known of their genetic bases and what remains to be discovered.
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Affiliation(s)
- M E Ross
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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339
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Schimmelpfeng K, Gögel S, Klämbt C. The function of leak and kuzbanian during growth cone and cell migration. Mech Dev 2001; 106:25-36. [PMID: 11472832 DOI: 10.1016/s0925-4773(01)00402-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Axonal growth cones require an evolutionary conserved repulsive guidance system to ensure proper crossing of the CNS midline. In Drosophila, the Slit protein is a repulsive signal secreted by the midline glial cells. It binds to the Roundabout receptors, which are expressed on CNS axons in the longitudinal tracts but not in the commissural tracts. Here we present an analysis of the genes leak and kuzbanian and show that both genes are involved in the repulsive guidance system operating at the CNS midline. Mutations in leak, which encodes the Roundabout-2 Slit receptor, were first recovered by Nüsslein-Volhard and co-workers based on defects in the larval cuticle. Analysis of the head phenotype suggests that slit may be able to act as an attractive guidance cue while directing the movements of the dorsal ectodermal cell sheath. kuzbanian also regulates midline crossing of CNS axons. It encodes a metalloprotease of the ADAM family and genetically interacts with slit. Expression of a dominant negative Kuzbanian protein in the CNS midline cells results in an abnormal midline crossing of axons and prevents the clearance of the Roundabout receptor from commissural axons. Our analyses support a model in which Kuzbanian mediates the proteolytic activation of the Slit/Roundabout receptor complex.
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Affiliation(s)
- K Schimmelpfeng
- Institut für Neurobiologie, Universität Münster, Badestrasse 9, 48149, Münster, Germany
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340
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The leukocyte common antigen-related protein tyrosine phosphatase receptor regulates regenerative neurite outgrowth in vivo. J Neurosci 2001. [PMID: 11438588 DOI: 10.1523/jneurosci.21-14-05130.2001] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Drosophila and leech models of nervous system development demonstrate that protein tyrosine phosphatase (PTP) receptors regulate developmental neurite outgrowth. Whether PTP receptors regulate neurite outgrowth in adult systems or in regenerative states remains unknown. The leukocyte common antigen-related (LAR) receptor is known to be present in rodent dorsal root ganglion (DRG) neurons; therefore, the well established model of postcrush sciatic nerve regeneration was used to test the hypothesis that LAR is required for neurite outgrowth in the adult mammalian nervous system. In uninjured sciatic nerves, no differences in nerve morphology and sensory function were detected between wild-type and LAR-deficient littermate transgenic mice. Sciatic nerve crush resulted in increased LAR protein expression in DRG neurons. In addition, nerve injury led to an increase in the proportion of LAR protein isoforms known to have increased binding affinity to neurite-promoting laminin-nidogen complexes. Two weeks after nerve crush, morphological analysis of distal nerve segments in LAR-deficient transgenic mice demonstrated significantly decreased densities of myelinated fibers, decreased axonal areas, and increased myelin/axon area ratios compared with littermate controls. Electron microscopy analysis revealed a significant twofold reduction in the density of regenerating unmyelinated fibers in LAR-/- nerves distal to the crush site. Sensory testing at the 2 week time point revealed a corresponding 3 mm lag in the proximal-to-distal progression of functioning sensory fibers along the distal nerve segment. These studies introduce PTP receptors as a major new gene family regulating regenerative neurite outgrowth in vivo in the adult mammalian system.
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341
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Sabo SL, Ikin AF, Buxbaum JD, Greengard P. The Alzheimer amyloid precursor protein (APP) and FE65, an APP-binding protein, regulate cell movement. J Cell Biol 2001; 153:1403-14. [PMID: 11425871 PMCID: PMC2150733 DOI: 10.1083/jcb.153.7.1403] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
FE65 binds to the Alzheimer amyloid precursor protein (APP), but the function of this interaction has not been identified. Here, we report that APP and FE65 are involved in regulation of cell movement. APP and FE65 colocalize with actin and Mena, an Abl-associated signaling protein thought to regulate actin dynamics, in lamellipodia. APP and FE65 specifically concentrate with beta 1-integrin in dynamic adhesion sites known as focal complexes, but not in more static adhesion sites known as focal adhesions. Overexpression of APP accelerates cell migration in an MDCK cell wound--healing assay. Coexpression of APP and FE65 dramatically enhances the effect of APP on cell movement, probably by regulating the amount of APP at the cell surface. These data are consistent with a role for FE65 and APP, possibly in a Mena-containing macromolecular complex, in regulation of actin-based motility.
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Affiliation(s)
- S L Sabo
- Laboratory of Molecular and Cellular Neuroscience and the Zachary and Elizabeth M. Fisher Center, The Rockefeller University, New York, New York 10021, USA.
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342
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Lee JS, Ray R, Chien CB. Cloning and expression of three zebrafish roundabout homologs suggest roles in axon guidance and cell migration. Dev Dyn 2001; 221:216-30. [PMID: 11376489 DOI: 10.1002/dvdy.1136] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report the cloning and expression patterns of three novel zebrafish Roundabout homologs. The Roundabout (robo) gene encodes a transmembrane receptor that is essential for axon guidance in Drosophila and Robo family members have been implicated in cell migration. Analysis of extracellular domains and conserved cytoplasmic motifs shows that zebrafish Robo1 and Robo2 are orthologs of mammalian Robo1 and Robo2, respectively, while zebrafish Robo3 is likely to be an ortholog of mouse Rig-1. The three zebrafish robos are expressed in distinct but overlapping patterns during embryogenesis. They are highly expressed in the developing nervous system, including the olfactory system, visual system, hindbrain, cranial ganglia, spinal cord, and posterior lateral line primordium. They are also expressed in several nonneuronal tissues, including somites and fin buds. The timing and patterns of expression suggest roles for zebrafish robos in axon guidance and cell migration. Wiley-Liss, Inc.
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Affiliation(s)
- J S Lee
- Department of Neurobiology and Anatomy, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA
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343
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Nakagawa H, Miki H, Ito M, Ohashi K, Takenawa T, Miyamoto S. N-WASP, WAVE and Mena play different roles in the organization of actin cytoskeleton in lamellipodia. J Cell Sci 2001; 114:1555-65. [PMID: 11282031 DOI: 10.1242/jcs.114.8.1555] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
WASP- and Ena/VASP-family proteins have been reported to regulate the cortical actin cytoskeleton as downstream effectors of the Ρ-family small G-proteins Rac and Cdc42, but their functions are little understood. We observed the localization of the WASP family proteins, N-WASP and WAVE, and the Ena/VASP family protein, Mena, in protruding lamellipodia. Rat fibroblast cell line 3Y1 protruded lamellipodia on poly-L-lysine-coated substrate without any trophic factor. N-WASP and Cdc42 were concentrated along the actin filament bundles of microspikes but not at the tips. By immunofluorescence and immunoelectron microscopy, both WAVE and Mena were observed to localize at the lamellipodium edge. Interestingly, Mena tended to concentrate at the microspike tips but WAVE did not. At the edge of the lamellipodium, the correlation between the fluorescence from Mena and actin filaments stained with the specific antibody and rhodamine-phalloidin, respectively, was much higher than that between WAVE and actin filament. The Ena/VASP homology 2 (EVH2) domain of avian Ena, an avian homolog of Mena, was localized to the lamellipodium edge and concentrated at the tip of microspikes. The SCAR homology domain (SHD) of human WAVE was distributed along the lamellipodium edge. These results indicate that N-WASP, WAVE and Mena have different roles in the regulation of the cortical actin cytoskeleton in the protruding lamellipodium. WAVE and Mena should be recruited to the lamellipodium edge through SHD and the EVH2 domain, respectively, to regulate the actin polymerization near the cell membrane. N-WASP should regulate the formation of the actin filament bundle in addition to activating Arp2/3 complex in lamellipodium under the control of Cdc42.
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Affiliation(s)
- H Nakagawa
- Dept of Biochemical Engineering and Science, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan.
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344
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Affiliation(s)
- R J Giger
- Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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345
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The N-terminal leucine-rich regions in Slit are sufficient to repel olfactory bulb axons and subventricular zone neurons. J Neurosci 2001. [PMID: 11222645 DOI: 10.1523/jneurosci.21-05-01548.2001] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Slit proteins are a new family of secreted guidance cues involved in axon guidance and neuronal migration. Each mammalian Slit protein contains >1400 amino acid residues, with four leucine-rich regions (LRRs), nine epidermal growth factor repeats, a laminin G domain, and a C-terminal cysteine-rich domain. A receptor for Slit is the transmembrane protein Roundabout (Robo), whose extracellular part contains five Ig domains and three fibronectin type III repeats. We report here that the LRRs in Slit are sufficient for binding to the Ig domains of Robo. Mutant forms of Slit containing only the LRRs function as chemorepellents for axons projecting from the olfactory bulb both in vitro and in the telencephalon. The LRRs can repel neurons migrating from the anterior subventricular zone (SVZa) to the olfactory bulb in brain slices isolated from neonatal rodents. However, the LRRs do not show repulsive effects on the SVZa neurons migrating in collagen gels. Our results indicate that the same LRRs are sufficient for guiding both axon projection and neuronal migration and suggest that the other regions in the Slit proteins may be involved in regulating the diffusion and distribution of the Slit proteins. The fact that the same domains are involved in guiding axon projection and neuronal migration further strengthens the idea of a conserved guidance mechanism for these important processes.
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346
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Abstract
Recent technical advances have made possible the visualization and genetic manipulation of individual dendritic trees. These studies have led to the identification and characterization of molecules that are important for different aspects of dendritic development. Although much remains to be learned, the existing knowledge has allowed us to take initial steps toward a comprehensive understanding of how complex dendritic trees are built. In this review, we describe recent advances in our understanding of the molecular mechanisms underlying dendritic morphogenesis, and discuss their cell-biological implications.
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Affiliation(s)
- E K Scott
- Department of Biological Sciences, Stanford University, Stanford, California 94305, USA
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347
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Kim YS, Furman S, Sink H, VanBerkum MF. Calmodulin and profilin coregulate axon outgrowth in Drosophila. JOURNAL OF NEUROBIOLOGY 2001; 47:26-38. [PMID: 11257611 DOI: 10.1002/neu.1013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coordinated regulation of actin cytoskeletal dynamics is critical to growth cone movement. The intracellular molecules calmodulin and profilin actively regulate actin-based motility and participate in the signaling pathways used to steer growth cones. Here we show that in the developing Drosophila embryo, calmodulin and profilin convey complimentary information that is necessary for appropriate growth cone advance. Reducing calmodulin activity by expression of a dominant inhibitor (KA) stalls axon extension of pioneer neurons within the CNS, while a partial loss of profilin function decreases extension of motor axons in the periphery. Yet, surprisingly, when calmodulin and profilin are simultaneously reduced, the ability of both CNS pioneer axons and motor axons to extend beyond the choice points is restored. In the CNS, at the time when growth cones must decide whether to cross or not to cross the midline, a reduction in calmodulin and/or roundabout signaling causes axons to cross the midline inappropriately. These inappropriate crossings are suppressed when profilin activity is simultaneously reduced. Interestingly, the mutual suppression of calmodulin and profilin activity requires a minimal level of profilin. In KA combinations with profilin null alleles, defects in axon extension and midline guidance are synergistically enhanced rather than suppressed. Together, our data indicate that the growth cone must coordinate the activity of both calmodulin and profilin in order to advance past selected choice points, including those dictating midline crossovers.
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Affiliation(s)
- Y S Kim
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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348
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Abstract
Cellular actin assembly is tightly regulated. The study of pathogen motility has led to the identification of several cellular factors that are critical for controlling this process. Pathogens such as Listeria require Ena/VASP and Arp2/3 proteins to translate actin polymerization into movement. Recent work has extended these observations and uncovered some similarities and surprising differences in the way cells and pathogens utilize the actin cytoskeleton.
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Affiliation(s)
- J E Bear
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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349
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Abstract
Proteins of the Ena/VASP (Enabled/vasodilator-stimulated phosphoprotein) family are involved in Abl and/or cyclic nucleotide-dependent protein kinase signaling pathways. These proteins are also crucial factors in regulating actin dynamics and associated processes such as cell-cell adhesion, platelet function and actin-based motility of both cytopathogenic Listeria and their eukaryotic host cells. Although biochemical mechanisms have emerged depicting Ena/VASP proteins as enhancers of actin filament formation, increasing evidence also suggests that these proteins have inhibitory functions in integrin regulation, cell motility and axon guidance.
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Affiliation(s)
- M Reinhard
- Institut für Klinische Biochemie und Pathobiochemie, Klinikum der Universität Würzburg, Versbacher Str. 5, D-97078, Würzburg, Germany.
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350
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Affiliation(s)
- B J Dickson
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
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