1
|
Wong W, Estep JA, Treptow AM, Rajabli N, Jahncke JN, Ubina T, Wright KM, Riccomagno MM. An adhesion signaling axis involving Dystroglycan, β1-Integrin, and Cas adaptor proteins regulates the establishment of the cortical glial scaffold. PLoS Biol 2023; 21:e3002212. [PMID: 37540708 PMCID: PMC10431685 DOI: 10.1371/journal.pbio.3002212] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 08/16/2023] [Accepted: 06/23/2023] [Indexed: 08/06/2023] Open
Abstract
The mature mammalian cortex is composed of 6 architecturally and functionally distinct layers. Two key steps in the assembly of this layered structure are the initial establishment of the glial scaffold and the subsequent migration of postmitotic neurons to their final position. These processes involve the precise and timely regulation of adhesion and detachment of neural cells from their substrates. Although much is known about the roles of adhesive substrates during neuronal migration and the formation of the glial scaffold, less is understood about how these signals are interpreted and integrated within these neural cells. Here, we provide in vivo evidence that Cas proteins, a family of cytoplasmic adaptors, serve a functional and redundant role during cortical lamination. Cas triple conditional knock-out (Cas TcKO) mice display severe cortical phenotypes that feature cobblestone malformations. Molecular epistasis and genetic experiments suggest that Cas proteins act downstream of transmembrane Dystroglycan and β1-Integrin in a radial glial cell-autonomous manner. Overall, these data establish a new and essential role for Cas adaptor proteins during the formation of cortical circuits and reveal a signaling axis controlling cortical scaffold formation.
Collapse
Affiliation(s)
- Wenny Wong
- Neuroscience Graduate Program, University of California, Riverside, California, United States of America
| | - Jason A. Estep
- Cell, Molecular and Developmental Biology Graduate Program, Department of Molecular, Cell & Systems Biology, University of California, Riverside, California, United States of America
| | - Alyssa M. Treptow
- Cell, Molecular and Developmental Biology Graduate Program, Department of Molecular, Cell & Systems Biology, University of California, Riverside, California, United States of America
| | - Niloofar Rajabli
- Cell, Molecular and Developmental Biology Graduate Program, Department of Molecular, Cell & Systems Biology, University of California, Riverside, California, United States of America
| | - Jennifer N. Jahncke
- Neuroscience Graduate Program, Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Teresa Ubina
- Neuroscience Graduate Program, University of California, Riverside, California, United States of America
| | - Kevin M. Wright
- Neuroscience Graduate Program, Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Martin M. Riccomagno
- Neuroscience Graduate Program, University of California, Riverside, California, United States of America
- Cell, Molecular and Developmental Biology Graduate Program, Department of Molecular, Cell & Systems Biology, University of California, Riverside, California, United States of America
| |
Collapse
|
2
|
Breau MA, Trembleau A. Chemical and mechanical control of axon fasciculation and defasciculation. Semin Cell Dev Biol 2023; 140:72-81. [PMID: 35810068 DOI: 10.1016/j.semcdb.2022.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/14/2022] [Accepted: 06/21/2022] [Indexed: 01/28/2023]
Abstract
Neural networks are constructed through the development of robust axonal projections from individual neurons, which ultimately establish connections with their targets. In most animals, developing axons assemble in bundles to navigate collectively across various areas within the central nervous system or the periphery, before they separate from these bundles in order to find their specific targets. These processes, called fasciculation and defasciculation respectively, were thought for many years to be controlled chemically: while guidance cues may attract or repulse axonal growth cones, adhesion molecules expressed at the surface of axons mediate their fasciculation. Recently, an additional non-chemical parameter, the mechanical longitudinal tension of axons, turned out to play a role in axon fasciculation and defasciculation, through zippering and unzippering of axon shafts. In this review, we present an integrated view of the currently known chemical and mechanical control of axon:axon dynamic interactions. We highlight the facts that the decision to cross or not to cross another axon depends on a combination of chemical, mechanical and geometrical parameters, and that the decision to fasciculate/defasciculate through zippering/unzippering relies on the balance between axon:axon adhesion and their mechanical tension. Finally, we speculate about possible functional implications of zippering-dependent axon shaft fasciculation, in the collective migration of axons, and in the sorting of subpopulations of axons.
Collapse
Affiliation(s)
- Marie Anne Breau
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS UMR 7622), Institut de Biologie Paris Seine (IBPS), Developmental Biology Laboratory, Paris, France
| | - Alain Trembleau
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS UMR8246), Inserm U1130, Institut de Biologie Paris Seine (IBPS), Neuroscience Paris Seine (NPS), Paris, France.
| |
Collapse
|
3
|
Moreland T, Poulain FE. To Stick or Not to Stick: The Multiple Roles of Cell Adhesion Molecules in Neural Circuit Assembly. Front Neurosci 2022; 16:889155. [PMID: 35573298 PMCID: PMC9096351 DOI: 10.3389/fnins.2022.889155] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 03/28/2022] [Indexed: 01/02/2023] Open
Abstract
Precise wiring of neural circuits is essential for brain connectivity and function. During development, axons respond to diverse cues present in the extracellular matrix or at the surface of other cells to navigate to specific targets, where they establish precise connections with post-synaptic partners. Cell adhesion molecules (CAMs) represent a large group of structurally diverse proteins well known to mediate adhesion for neural circuit assembly. Through their adhesive properties, CAMs act as major regulators of axon navigation, fasciculation, and synapse formation. While the adhesive functions of CAMs have been known for decades, more recent studies have unraveled essential, non-adhesive functions as well. CAMs notably act as guidance cues and modulate guidance signaling pathways for axon pathfinding, initiate contact-mediated repulsion for spatial organization of axonal arbors, and refine neuronal projections during circuit maturation. In this review, we summarize the classical adhesive functions of CAMs in axonal development and further discuss the increasing number of other non-adhesive functions CAMs play in neural circuit assembly.
Collapse
|
4
|
Kamemura K, Moriya H, Ukita Y, Okumura M, Miura M, Chihara T. Endoplasmic reticulum proteins Meigo and Gp93 govern dendrite targeting by regulating Toll-6 localization. Dev Biol 2022; 484:30-39. [DOI: 10.1016/j.ydbio.2022.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/29/2021] [Accepted: 02/02/2022] [Indexed: 12/15/2022]
|
5
|
Trans-Axonal Signaling in Neural Circuit Wiring. Int J Mol Sci 2020; 21:ijms21145170. [PMID: 32708320 PMCID: PMC7404203 DOI: 10.3390/ijms21145170] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/15/2020] [Accepted: 07/17/2020] [Indexed: 12/24/2022] Open
Abstract
The development of neural circuits is a complex process that relies on the proper navigation of axons through their environment to their appropriate targets. While axon–environment and axon–target interactions have long been known as essential for circuit formation, communication between axons themselves has only more recently emerged as another crucial mechanism. Trans-axonal signaling governs many axonal behaviors, including fasciculation for proper guidance to targets, defasciculation for pathfinding at important choice points, repulsion along and within tracts for pre-target sorting and target selection, repulsion at the target for precise synaptic connectivity, and potentially selective degeneration for circuit refinement. This review outlines the recent advances in identifying the molecular mechanisms of trans-axonal signaling and discusses the role of axon–axon interactions during the different steps of neural circuit formation.
Collapse
|
6
|
Luo X, Seveau de Noray V, Aoun L, Biarnes-Pelicot M, Strale PO, Studer V, Valignat MP, Theodoly O. Lymphocyte perform reverse adhesive haptotaxis mediated by integrins LFA-1. J Cell Sci 2020; 133:jcs.242883. [DOI: 10.1242/jcs.242883] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 07/13/2020] [Indexed: 01/10/2023] Open
Abstract
Cell Guidance by anchored molecules, or haptotaxis, is crucial in development, immunology and cancer. Adhesive haptotaxis, or guidance by adhesion molecules, is well established for mesenchymal cells like fibroblasts, whereas its existence remains unreported for amoeboid cells that require less or no adhesion to migrate. We show here in vitro that amoeboid human T lymphocytes develop adhesive haptotaxis versus densities of integrin ligands expressed by high endothelial venules. Moreover, lymphocytes orient towards increasing adhesion with VLA-4 integrins, like all mesenchymal cells, but towards decreasing adhesion with LFA-1 integrins, which has never been observed. This counterintuitive ‘reverse haptotaxis’ cannot be explained with the existing mesenchymal mechanisms of competition between cells’ pulling edges or of lamellipodia growth activated by integrins, which favor orientation towards increasing adhesion. Mechanisms and functions of amoeboid adhesive haptotaxis remain unclear, however multidirectional integrin-mediated haptotaxis may operate around transmigration ports on endothelium, stromal cells in lymph nodes, and inflamed tissue where integrin ligands are spatially modulated.
Collapse
Affiliation(s)
- Xuan Luo
- LAI, Aix Marseille Univ, CNRS, INSERM, Marseille, France
| | | | - Laurene Aoun
- LAI, Aix Marseille Univ, CNRS, INSERM, Marseille, France
| | | | | | - Vincent Studer
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, Bordeaux, France
- CNRS UMR 5297, F-33000 Bordeaux, France
| | | | | |
Collapse
|
7
|
Vahedi-Hunter TA, Estep JA, Rosette KA, Rutlin ML, Wright KM, Riccomagno MM. Cas Adaptor Proteins Coordinate Sensory Axon Fasciculation. Sci Rep 2018; 8:5996. [PMID: 29662228 PMCID: PMC5902548 DOI: 10.1038/s41598-018-24261-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 03/29/2018] [Indexed: 11/09/2022] Open
Abstract
Development of complex neural circuits like the peripheral somatosensory system requires intricate mechanisms to ensure axons make proper connections. While much is known about ligand-receptor pairs required for dorsal root ganglion (DRG) axon guidance, very little is known about the cytoplasmic effectors that mediate cellular responses triggered by these guidance cues. Here we show that members of the Cas family of cytoplasmic signaling adaptors are highly phosphorylated in central projections of the DRG as they enter the spinal cord. Furthermore, we provide genetic evidence that Cas proteins regulate fasciculation of DRG sensory projections. These data establish an evolutionarily conserved requirement for Cas adaptor proteins during peripheral nervous system axon pathfinding. They also provide insight into the interplay between axonal fasciculation and adhesion to the substrate.
Collapse
Affiliation(s)
- Tyler A Vahedi-Hunter
- Neuroscience Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Jason A Estep
- Cell, Molecular and Developmental Biology Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Kylee A Rosette
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Michael L Rutlin
- Department of Biochemistry and Molecular Biophysics, Columbia College of Physicians and Surgeons, Columbia University, New York, New York, 10032, USA
| | - Kevin M Wright
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Martin M Riccomagno
- Neuroscience Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA. .,Cell, Molecular and Developmental Biology Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA.
| |
Collapse
|
8
|
Grintsevich EE, Yesilyurt HG, Rich SK, Hung RJ, Terman JR, Reisler E. F-actin dismantling through a redox-driven synergy between Mical and cofilin. Nat Cell Biol 2016; 18:876-85. [PMID: 27454820 PMCID: PMC4966907 DOI: 10.1038/ncb3390] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/21/2016] [Indexed: 02/06/2023]
Abstract
Numerous cellular functions depend on actin filament (F-actin) disassembly. The
best-characterized disassembly proteins, the ADF/cofilins/twinstar, sever filaments and
recycle monomers to promote actin assembly. Cofilin is also a relatively weak actin
disassembler, posing questions about mechanisms of cellular F-actin destabilization. Here
we uncover a key link to targeted F-actin disassembly by finding that F-actin is
efficiently dismantled through a post-translational-mediated synergism between cofilin and
the actin-oxidizing enzyme Mical. We find that Mical-mediated oxidation of actin improves
cofilin binding to filaments, where their combined effect dramatically accelerates F-actin
disassembly compared to either effector alone. This synergism is also necessary and
sufficient for F-actin disassembly in vivo, magnifying the effects of
both Mical and cofilin on cellular remodeling, axon guidance, and Semaphorin/Plexin
repulsion. Mical and cofilin, therefore, form a Redox-dependent synergistic pair that
promotes F-actin instability by rapidly dismantling F-actin and generating
post-translationally modified actin that has altered assembly properties.
Collapse
Affiliation(s)
- Elena E Grintsevich
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, USA
| | - Hunkar Gizem Yesilyurt
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Shannon K Rich
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Ruei-Jiun Hung
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Jonathan R Terman
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, USA.,Molecular Biology Institute, University of California-Los Angeles, Los Angeles, California 90095, USA
| |
Collapse
|
9
|
Abstract
Neuronal growth cones are exquisite sensory-motor machines capable of transducing features contacted in their local extracellular environment into guided process extension during development. Extensive research has shown that chemical ligands activate cell surface receptors on growth cones leading to intracellular signals that direct cytoskeletal changes. However, the environment also provides mechanical support for growth cone adhesion and traction forces that stabilize leading edge protrusions. Interestingly, recent work suggests that both the mechanical properties of the environment and mechanical forces generated within growth cones influence axon guidance. In this review we discuss novel molecular mechanisms involved in growth cone force production and detection, and speculate how these processes may be necessary for the development of proper neuronal morphogenesis.
Collapse
Affiliation(s)
- Patrick C Kerstein
- Neuroscience Training Program, Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison Madison, WI, USA
| | - Robert H Nichol
- Neuroscience Training Program, Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison Madison, WI, USA
| | - Timothy M Gomez
- Neuroscience Training Program, Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison Madison, WI, USA
| |
Collapse
|
10
|
Camacho Leal MDP, Sciortino M, Tornillo G, Colombo S, Defilippi P, Cabodi S. p130Cas/BCAR1 scaffold protein in tissue homeostasis and pathogenesis. Gene 2015; 562:1-7. [PMID: 25727852 DOI: 10.1016/j.gene.2015.02.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/01/2015] [Indexed: 12/11/2022]
Abstract
BCAR1 (also known as p130Cas/BCAR1) is an adaptor protein that belongs to the CAS family of scaffold proteins. In the past years, increasing evidence has demonstrated the ability of p130Cas/BCAR1 to activate signaling originating from mechanical stimuli, cell-extracellular matrix (ECM) adhesion and growth factor stimulation cascades during normal development and disease in various biological models. In this review we will specifically discuss the more recent data on the contribution of p130Cas/BCAR1 in the regulation of tissue homeostasis and its potential implications in pathological conditions.
Collapse
Affiliation(s)
| | - Marianna Sciortino
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Italy
| | - Giusy Tornillo
- European Cancer Stem Cell Research Institute and Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - Shana Colombo
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Italy
| | - Paola Defilippi
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Italy
| | - Sara Cabodi
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Italy.
| |
Collapse
|
11
|
Riccomagno MM, Sun LO, Brady CM, Alexandropoulos K, Seo S, Kurokawa M, Kolodkin AL. Cas adaptor proteins organize the retinal ganglion cell layer downstream of integrin signaling. Neuron 2014; 81:779-86. [PMID: 24559672 DOI: 10.1016/j.neuron.2014.01.036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2014] [Indexed: 10/25/2022]
Abstract
Stratification of retinal neuronal cell bodies and lamination of their processes provide a scaffold upon which neural circuits can be built. However, the molecular mechanisms that direct retinal ganglion cells (RGCs) to resolve into a single-cell retinal ganglion cell layer (GCL) are not well understood. The extracellular matrix protein laminin conveys spatial information that instructs the migration, process outgrowth, and reorganization of GCL cells. Here, we show that the β1-Integrin laminin receptor is required for RGC positioning and reorganization into a single-cell GCL layer. β1-Integrin signaling within migrating GCL cells requires Cas signaling-adaptor proteins, and in the absence of β1-Integrin or Cas function retinal neurons form ectopic cell clusters beyond the inner-limiting membrane (ILM), phenocopying laminin mutants. These data reveal an essential role for Cas adaptor proteins in β1-Integrin-mediated signaling events critical for the formation of the single-cell GCL in the mammalian retina.
Collapse
Affiliation(s)
- Martin M Riccomagno
- The Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Lu O Sun
- The Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Colleen M Brady
- The Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Konstantina Alexandropoulos
- Department of Medicine, Division of Clinical Immunology, The Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Sachiko Seo
- Department of Hematology & Oncology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Mineo Kurokawa
- Department of Hematology & Oncology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Alex L Kolodkin
- The Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| |
Collapse
|
12
|
Santiago C, Labrador JP, Bashaw GJ. The homeodomain transcription factor Hb9 controls axon guidance in Drosophila through the regulation of Robo receptors. Cell Rep 2014; 7:153-65. [PMID: 24685136 DOI: 10.1016/j.celrep.2014.02.037] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 02/06/2014] [Accepted: 02/25/2014] [Indexed: 02/05/2023] Open
Abstract
Transcription factors establish neural diversity and wiring specificity; however, how they orchestrate changes in cell morphology remains poorly understood. The Drosophila Roundabout (Robo) receptors regulate connectivity in the CNS, but how their precise expression domains are established is unknown. Here, we show that the homeodomain transcription factor Hb9 acts upstream of Robo2 and Robo3 to regulate axon guidance in the Drosophila embryo. In ventrally projecting motor neurons, hb9 is required for robo2 expression, and restoring Robo2 activity in hb9 mutants rescues motor axon defects. Hb9 requires its conserved repressor domain and functions in parallel with Nkx6 to regulate robo2. Moreover, hb9 can regulate the medio-lateral position of axons through robo2 and robo3, and restoring robo3 expression in hb9 mutants rescues the lateral position defects of a subset of neurons. Altogether, these data identify Robo2 and Robo3 as key effectors of Hb9 in regulating nervous system development.
Collapse
Affiliation(s)
- Celine Santiago
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| |
Collapse
|
13
|
What axons tell each other: axon-axon signaling in nerve and circuit assembly. Curr Opin Neurobiol 2013; 23:974-82. [PMID: 23973157 DOI: 10.1016/j.conb.2013.08.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 08/02/2013] [Accepted: 08/05/2013] [Indexed: 01/29/2023]
Abstract
A remarkable feature of nervous system development is the ability of axons emerging from newly formed neurons to traverse, by cellular scale, colossal distances to appropriate targets. The earliest axons achieve this in an essentially axon-free environment, but the vast majority of axons eventually grow along a scaffold of nerve tracts created by earlier extending axons. Signal exchange between sequentially or simultaneously extending axons may well represent the predominant mode of axonal navigation, but proportionally few efforts have so far been directed at deciphering the underlying mechanisms. This review intends to provide a conceptual update on the cellular and molecular principles driving axon-axon interactions, with emphasis on those contributing to the fidelity of axonal navigation, sorting and connectivity during nerve and circuit assembly.
Collapse
|
14
|
Chen S, Charness ME. Ethanol disrupts axon outgrowth stimulated by netrin-1, GDNF, and L1 by blocking their convergent activation of Src family kinase signaling. J Neurochem 2012; 123:602-12. [PMID: 22924694 DOI: 10.1111/j.1471-4159.2012.07954.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/23/2012] [Accepted: 08/23/2012] [Indexed: 01/17/2023]
Abstract
Pre-natal alcohol exposure causes fetal alcohol spectrum disorders (FASD), the most common, preventable cause of developmental disability. The developing cerebellum is particularly vulnerable to the effects of ethanol. We reported that ethanol inhibits the stimulation of axon outgrowth in cerebellar granule neurons (CGN) by NAP, an active motif of activity-dependent neuroprotective protein (ADNP), by blocking NAP activation of Fyn kinase and its downstream signaling molecule, the scaffolding protein Cas. Here, we asked whether ethanol inhibits the stimulation of axon outgrowth by diverse axon guidance molecules through a common action on the Src family kinases (SFK). We first demonstrated that netrin-1, glial cell line-derived neurotrophic factor (GDNF), and neural cell adhesion molecule L1 stimulate axon outgrowth in CGNs by activating SFK, Cas, and extracellular signal-regulated kinase 1 and 2 (ERK1/2). The specific SFK inhibitor, PP2, blocked the stimulation of axon outgrowth and the activation of the SFK-Cas-ERK1/2 signaling pathway by each of these axon-guidance molecules. In contrast, brain-derived neurotrophic factor (BDNF) stimulated axon outgrowth and activated ERK1/2 without first activating SFK or Cas. Clinically relevant concentrations of ethanol inhibited axon outgrowth and the activation of the SFK-Cas-ERK1/2 pathway by netrin-1, GDNF, and L1, but did not disrupt BDNF-induced axon outgrowth or ERK1/2 activation. These results indicate that SFK, but not ERK1/2, is a primary target for ethanol inhibition of axon outgrowth. The ability of ethanol to block the convergent activation of the SFK-Cas-ERK1/2 pathway by netrin-1, GDNF, L1, and ADNP could contribute significantly to the pathogenesis of FASD.
Collapse
Affiliation(s)
- Suzhen Chen
- VA Boston Healthcare System and Department of Neurology, Harvard Medical School, West Roxbury, MA, USA
| | | |
Collapse
|
15
|
Cell adhesion in Drosophila: versatility of cadherin and integrin complexes during development. Curr Opin Cell Biol 2012; 24:702-12. [PMID: 22938782 DOI: 10.1016/j.ceb.2012.07.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/16/2012] [Accepted: 07/26/2012] [Indexed: 01/22/2023]
Abstract
We highlight recent progress in understanding cadherin and integrin function in the model organism Drosophila. New functions for these adhesion receptors continue to be discovered in this system, emphasising the importance of cell adhesion within the developing organism and showing that the requirement for cell adhesion changes between cell types. New ways to control adhesion have been discovered, including controlling the expression and recruitment of adhesion components, their posttranslational modification, recycling and turnover. Importantly, even ubiquitous adhesion components can function differently in distinct cellular contexts.
Collapse
|
16
|
Yang T, Terman JR. 14-3-3ε couples protein kinase A to semaphorin signaling and silences plexin RasGAP-mediated axonal repulsion. Neuron 2012; 74:108-21. [PMID: 22500634 DOI: 10.1016/j.neuron.2011.12.034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2011] [Indexed: 10/28/2022]
Abstract
The biochemical means through which multiple signaling pathways are integrated in navigating axons is poorly understood. Semaphorins are among the largest families of axon guidance cues and utilize Plexin (Plex) receptors to exert repulsive effects on axon extension. However, Semaphorin repulsion can be silenced by other distinct cues and signaling cascades, raising questions of the logic underlying these events. We now uncover a simple biochemical switch that controls Semaphorin/Plexin repulsive guidance. Plexins are Ras/Rap family GTPase activating proteins (GAPs) and we find that the PlexA GAP domain is phosphorylated by the cAMP-dependent protein kinase (PKA). This PlexA phosphorylation generates a specific binding site for 14-3-3ε, a phospho-binding protein that we find to be necessary for axon guidance. These PKA-mediated Plexin-14-3-3ε interactions prevent PlexA from interacting with its Ras family GTPase substrate and antagonize Semaphorin repulsion. Our results indicate that these interactions switch repulsion to adhesion and identify a point of convergence for multiple guidance molecules.
Collapse
Affiliation(s)
- Taehong Yang
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | |
Collapse
|
17
|
Myers JP, Santiago-Medina M, Gomez TM. Regulation of axonal outgrowth and pathfinding by integrin-ECM interactions. Dev Neurobiol 2011; 71:901-23. [PMID: 21714101 PMCID: PMC3192254 DOI: 10.1002/dneu.20931] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Developing neurons use a combination of guidance cues to assemble a functional neural network. A variety of proteins immobilized within the extracellular matrix (ECM) provide specific binding sites for integrin receptors on neurons. Integrin receptors on growth cones associate with a number of cytosolic adaptor and signaling proteins that regulate cytoskeletal dynamics and cell adhesion. Recent evidence suggests that soluble growth factors and classic axon guidance cues may direct axon pathfinding by controlling integrin-based adhesion. Moreover, because classic axon guidance cues themselves are immobilized within the ECM and integrins modulate cellular responses to many axon guidance cues, interactions between activated receptors modulate cell signals and adhesion. Ultimately, growth cones control axon outgrowth and pathfinding behaviors by integrating distinct biochemical signals to promote the proper assembly of the nervous system. In this review, we discuss our current understanding how ECM proteins and their associated integrin receptors control neural network formation.
Collapse
Affiliation(s)
- Jonathan P Myers
- Department of Neuroscience, Neuroscience Training Program, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | |
Collapse
|
18
|
Broadie K, Baumgartner S, Prokop A. Extracellular matrix and its receptors in Drosophila neural development. Dev Neurobiol 2011; 71:1102-30. [PMID: 21688401 PMCID: PMC3192297 DOI: 10.1002/dneu.20935] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Extracellular matrix (ECM) and matrix receptors are intimately involved in most biological processes. The ECM plays fundamental developmental and physiological roles in health and disease, including processes underlying the development, maintenance, and regeneration of the nervous system. To understand the principles of ECM-mediated functions in the nervous system, genetic model organisms like Drosophila provide simple, malleable, and powerful experimental platforms. This article provides an overview of ECM proteins and receptors in Drosophila. It then focuses on their roles during three progressive phases of neural development: (1) neural progenitor proliferation, (2) axonal growth and pathfinding, and (3) synapse formation and function. Each section highlights known ECM and ECM-receptor components and recent studies done in mutant conditions to reveal their in vivo functions, all illustrating the enormous opportunities provided when merging work on the nervous system with systematic research into ECM-related gene functions.
Collapse
Affiliation(s)
- Kendal Broadie
- Departments of Biological Sciences and Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232 USA
| | - Stefan Baumgartner
- Department of Experimental Medical Sciences, Lund University, BMC B12, 22184 Lund, Sweden
| | - Andreas Prokop
- Faculty of Life Sciences, Wellcome Trust Centre for Cell-Matrix Research, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| |
Collapse
|
19
|
Roselli S, Wallez Y, Wang L, Vervoort V, Pasquale EB. The SH2 domain protein Shep1 regulates the in vivo signaling function of the scaffolding protein Cas. Cell Signal 2010; 22:1745-52. [PMID: 20603213 PMCID: PMC2948029 DOI: 10.1016/j.cellsig.2010.06.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 06/29/2010] [Indexed: 01/07/2023]
Abstract
The members of the p130Cas (Cas) family are important scaffolding proteins that orchestrate cell adhesion, migration and invasiveness downstream of integrin adhesion receptors and receptor tyrosine kinases by recruiting enzymes and structural molecules. Shep1, BCAR3/AND-34 and NSP1 define a recently identified family of SH2 domain-containing proteins that constitutively bind Cas proteins through a Cdc25-type nucleotide exchange factor-like domain. To gain insight into the functional interplay between Shep1 and Cas in vivo, we have inactivated the Shep1 gene in the mouse through Cre-mediated deletion of the exon encoding the SH2 domain. Analysis of Cas tyrosine phosphorylation in the brains of newborn mice, where Shep1 is highly expressed, revealed a strong decrease in Cas substrate domain phosphorylation in knockout compared to wild-type brains. Src family kinases bind to Cas via their SH3 and SH2 domains, which contributes to their activation, and phosphorylate multiple tyrosines in the Cas substrate domain. These tyrosine-phosphorylated motifs represent docking sites for the Crk adaptor, linking Cas to the downstream Rac1 and Rap1 GTPases to regulate cell adhesion and actin cytoskeleton organization. Accordingly, we detected lower Cas-Crk association and lower phosphorylation of the Src activation loop in Shep1 knockout brains compared to wild-type. Conversely, Shep1 transfection in COS cells increases Cas tyrosine phosphorylation. The SH2 domain is likely critical for the effects of Shep1 on Cas and Src signaling because the knockout mice express Shep1 fragments that lack the amino-terminal region including the SH2 domain, presumably due to aberrant translation from internal ATG codons. These fragments retain the ability to increase Cas levels in transfected cells, similar to full-length Shep1. However, they do not affect Cas phosphorylation on their own or in the presence of co-transfected full-length Shep1. They also do not show dominant negative effects on the activity of full-length Shep1 in vivo because the heterozygous mice, which express the fragments, have a normal life span. This is in contrast to the homozygous knockout mice, most of which die soon after birth. These data demonstrate that Shep1 plays a critical role in the in vivo regulation of Src activity and Cas downstream signaling through Crk, and suggest that the SH2 domain of Shep1 is critical for these effects.
Collapse
Affiliation(s)
- Séverine Roselli
- Sanford-Burnham Medical Research Institute, 10901 N Torrey Pines Rd, La Jolla, CA 92037, USA
| | | | | | | | | |
Collapse
|
20
|
The SRC homology 2 domain protein Shep1 plays an important role in the penetration of olfactory sensory axons into the forebrain. J Neurosci 2010; 30:13201-10. [PMID: 20881139 DOI: 10.1523/jneurosci.3289-10.2010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Shep1 is a multidomain signaling protein that forms a complex with Cas, a key scaffolding component of integrin signaling pathways, to promote the migration of non-neuronal cells. However, the physiological function of Shep1 in the nervous system remains unknown. Interestingly, we found that Shep1 and Cas are both concentrated in the axons of developing olfactory sensory neurons (OSNs). These neurons extend their axons from the olfactory epithelium to the olfactory bulb located at the anterior tip of the forebrain. However, in developing Shep1 knock-out mice, we did not detect penetration of OSN axons across the pial basement membrane surrounding the olfactory bulb, suggesting that Shep1 function is important for the establishment of OSN connections with the olfactory bulb. Interestingly, we observed reduced levels of Cas tyrosine phosphorylation in OSN axons of Shep1 knock-out mice, suggesting compromised Cas signaling function. Indeed, when embedded in a three-dimensional gel of basement membrane proteins, explants from Shep1 knock-out olfactory epithelium extend neuronal processes less efficiently than explants from control epithelium. Furthermore, ectopic expression of Shep1 in non-neuronal cells promotes cell migration through a collagen gel. Later in development, loss of Shep1 function also causes a marked reduction in olfactory bulb size and disruption of bulb lamination, which may be primarily attributable to the defective innervation. The greatly reduced OSN connections and hypoplasia of the olfactory bulb, likely resulting in anosmia, are reminiscent of the symptoms of Kallmann syndrome, a human developmental disease that can be caused by mutations in a growing number of genes.
Collapse
|
21
|
Renfranz PJ, Blankman E, Beckerle MC. The cytoskeletal regulator zyxin is required for viability in Drosophila melanogaster. Anat Rec (Hoboken) 2010; 293:1455-69. [PMID: 20648572 DOI: 10.1002/ar.21193] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The zyxin family of proteins function as cytoskeletal regulators in adhesion, actin assembly, and cell motility. Though fibroblasts derived from zyxin-null mice show striking defects in motility and response to mechanical stimuli, the mice are viable and fertile. In Drosophila melanogaster, the family is represented by a single homologue, Zyx102. To study the role of zyxin during development, we generated a zyx102 RNA-interference transgenic line that allows for the conditional knockdown of Zyx102. When UAST-zyx102-dsRNAi expression is driven broadly by Actin5C-GAL4, loss of Zyx102 results in lethality during the pharate adult stage, a narrow developmental window during which the fly must molt, resorb molting fluid, fill adult trachea with air, and execute a behavioral program to eclose. Zyx102 knockdown animals attempt to emerge, but their adult trachea do not fill with air. If dissected from the pupal case, knockdown individuals appear morphologically normal, but remain inviable.
Collapse
Affiliation(s)
- Patricia J Renfranz
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112-5550, USA
| | | | | |
Collapse
|
22
|
Tikhmyanova N, Tulin AV, Roegiers F, Golemis EA. Dcas supports cell polarization and cell-cell adhesion complexes in development. PLoS One 2010; 5:e12369. [PMID: 20808771 PMCID: PMC2927436 DOI: 10.1371/journal.pone.0012369] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 07/29/2010] [Indexed: 01/17/2023] Open
Abstract
Mammalian Cas proteins regulate cell migration, division and survival, and are often deregulated in cancer. However, the presence of four paralogous Cas family members in mammals (BCAR1/p130Cas, EFS/Sin1, NEDD9/HEF1/Cas-L, and CASS4/HEPL) has limited their analysis in development. We deleted the single Drosophila Cas gene, Dcas, to probe the developmental function of Dcas. Loss of Dcas had limited effect on embryonal development. However, we found that Dcas is an important modulator of the severity of the developmental phenotypes of mutations affecting integrins (If and mew) and their downstream effectors Fak56D or Src42A. Strikingly, embryonic lethal Fak56D-Dcas double mutant embryos had extensive cell polarity defects, including mislocalization and reduced expression of E-cadherin. Further genetic analysis established that loss of Dcas modified the embryonal lethal phenotypes of embryos with mutations in E-cadherin (Shg) or its signaling partners p120- and beta-catenin (Arm). These results support an important role for Cas proteins in cell-cell adhesion signaling in development.
Collapse
Affiliation(s)
- Nadezhda Tikhmyanova
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
- Department of Biochemistry, Drexel University Medical School, Philadelphia, Pennsylvania, United States of America
| | - Alexei V. Tulin
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Fabrice Roegiers
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Erica A. Golemis
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| |
Collapse
|
23
|
Tikhmyanova N, Little JL, Golemis EA. CAS proteins in normal and pathological cell growth control. Cell Mol Life Sci 2010; 67:1025-48. [PMID: 19937461 PMCID: PMC2836406 DOI: 10.1007/s00018-009-0213-1] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 11/03/2009] [Accepted: 11/09/2009] [Indexed: 12/20/2022]
Abstract
Proteins of the CAS (Crk-associated substrate) family (BCAR1/p130Cas, NEDD9/HEF1/Cas-L, EFS/SIN and CASS4/HEPL) are integral players in normal and pathological cell biology. CAS proteins act as scaffolds to regulate protein complexes controlling migration and chemotaxis, apoptosis, cell cycle, and differentiation, and have more recently been linked to a role in progenitor cell function. Reflecting these complex functions, over-expression of CAS proteins has now been strongly linked to poor prognosis and increased metastasis in cancer, as well as resistance to first-line chemotherapeutics in multiple tumor types including breast and lung cancers, glioblastoma, and melanoma. Further, CAS proteins have also been linked to additional pathological conditions including inflammatory disorders, Alzheimer's and Parkinson's disease, as well as developmental defects. This review will explore the roles of the CAS proteins in normal and pathological states in the context of the many mechanistic insights into CAS protein function that have emerged in the past decade.
Collapse
Affiliation(s)
- Nadezhda Tikhmyanova
- Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111 USA
- Department of Biochemistry, Drexel University Medical School, Philadelphia, PA 19102 USA
| | - Joy L. Little
- Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111 USA
| | - Erica A. Golemis
- Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111 USA
| |
Collapse
|
24
|
Barouki R, Coumoul X. Cell migration and metastasis markers as targets of environmental pollutants and the Aryl hydrocarbon receptor. Cell Adh Migr 2010; 4:72-6. [PMID: 20009531 DOI: 10.4161/cam.4.1.10313] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
During the last few years, several studies have pointed to a surprising link between environmental pollutants cellular signaling and important cell functions such as plasticity, adhesion and migration. This unexpected link could be related to endogenous functions of pollutants receptors that may be disrupted by environmental factors, which is supported by observations in invertebrate species. It could also reveal novel toxic end-points and mechanisms of those pollutants, such as teratogenesis and cancer metastasis that are highly relevant from a public health point of view. In the present short article, we will review our recent observations on the aryl hydrocarbon receptor and its new molecular and cellular targets. We identified HEF1/NEDD9/CAS-L, a multifunctional protein involved in integrin-based signaling as a transcriptional target of the receptor, and showed that its induction was critical for cell plasticity mediated by environmental pollutants. We will put our studies in perspective with other observations made by several groups.
Collapse
|
25
|
A genetic pathway composed of Sox14 and Mical governs severing of dendrites during pruning. Nat Neurosci 2009; 12:1497-505. [PMID: 19881505 PMCID: PMC3101876 DOI: 10.1038/nn.2415] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 09/04/2009] [Indexed: 11/08/2022]
Abstract
Pruning that selectively eliminates neuronal processes is crucial for the refinement of neural circuits during development. In Drosophila, the class IV dendritic arborization neuron (ddaC) undergoes pruning to remove its larval dendrites during metamorphosis. We identified Sox14 as a transcription factor that was necessary and sufficient to mediate dendrite severing during pruning in response to ecdysone signaling. We found that Sox14 mediated dendrite pruning by directly regulating the expression of the target gene mical. mical Encodes a large cytosolic protein with multiple domains that are known to associate with cytoskeletal components. mical Mutants had marked severing defects during dendrite pruning that were similar to those of sox14 mutants. Overexpression of Mical could significantly rescue pruning defects in sox14 mutants, suggesting that Mical is a major downstream target of Sox14 during pruning. Thus, our findings indicate that a previously unknown pathway composed of Sox14 and its cytoskeletal target Mical governs dendrite severing.
Collapse
|
26
|
Birge RB, Kalodimos C, Inagaki F, Tanaka S. Crk and CrkL adaptor proteins: networks for physiological and pathological signaling. Cell Commun Signal 2009; 7:13. [PMID: 19426560 PMCID: PMC2689226 DOI: 10.1186/1478-811x-7-13] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 05/10/2009] [Indexed: 01/24/2023] Open
Abstract
The Crk adaptor proteins (Crk and CrkL) constitute an integral part of a network of essential signal transduction pathways in humans and other organisms that act as major convergence points in tyrosine kinase signaling. Crk proteins integrate signals from a wide variety of sources, including growth factors, extracellular matrix molecules, bacterial pathogens, and apoptotic cells. Mounting evidence indicates that dysregulation of Crk proteins is associated with human diseases, including cancer and susceptibility to pathogen infections. Recent structural work has identified new and unusual insights into the regulation of Crk proteins, providing a rationale for how Crk can sense diverse signals and produce a myriad of biological responses.
Collapse
Affiliation(s)
- Raymond B Birge
- Department of Biochemistry & Molecular Biology, UMDNJ-New Jersey Medical School, 185 South Orange Ave, Newark, NJ 07103, USA.
| | | | | | | |
Collapse
|
27
|
The glucose transporter (GLUT4) enhancer factor is required for normal wing positioning in Drosophila. Genetics 2008; 178:919-29. [PMID: 18245850 DOI: 10.1534/genetics.107.078030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Many of the transcription factors and target genes that pattern the developing adult remain unknown. In the present study, we find that an ortholog of the poorly understood transcription factor, glucose transporter (GLUT4) enhancer factor (Glut4EF, GEF) [also known as the Huntington's disease gene regulatory region-binding protein (HDBP) 1], plays a critical role in specifying normal wing positioning in adult Drosophila. Glut4EF proteins are zinc-finger transcription factors named for their ability to regulate expression of GLUT4 but nothing is known of Glut4EF's in vivo physiological functions. Here, we identify a family of Glut4EF proteins that are well conserved from Drosophila to humans and find that mutations in Drosophila Glut4EF underlie the wing-positioning defects seen in stretch mutants. In addition, our results indicate that previously uncharacterized mutations in Glut4EF are present in at least 11 publicly available fly lines and on the widely used TM3 balancer chromosome. These results indicate that previous observations utilizing these common stocks may be complicated by the presence of Glut4EF mutations. For example, our results indicate that Glut4EF mutations are also present on the same chromosome as two gain-of-function mutations of the homeobox transcription factor Antennapedia (Antp) and underlie defects previously attributed to Antp. In fact, our results support a role for Glut4EF in the modulation of morphogenetic processes mediated by Antp, further highlighting the importance of Glut4EF transcription factors in patterning and morphogenesis.
Collapse
|