1
|
Carretero-Rodriguez L, Guðjónsdóttir R, Poparic I, Reilly ML, Chol M, Bianco IH, Chiapello M, Feret R, Deery MJ, Guthrie S. The Rac-GAP alpha2-Chimaerin Signals via CRMP2 and Stathmins in the Development of the Ocular Motor System. J Neurosci 2021; 41:6652-6672. [PMID: 34168008 PMCID: PMC8336708 DOI: 10.1523/jneurosci.0983-19.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 11/21/2022] Open
Abstract
A precise sequence of axon guidance events is required for the development of the ocular motor system. Three cranial nerves grow toward, and connect with, six extraocular muscles in a stereotyped pattern, to control eye movements. The signaling protein alpha2-chimaerin (α2-CHN) plays a pivotal role in the formation of the ocular motor system; mutations in CHN1, encoding α2-CHN, cause the human eye movement disorder Duane Retraction Syndrome (DRS). Our research has demonstrated that the manipulation of α2-chn signaling in the zebrafish embryo leads to ocular motor axon wiring defects, although the signaling cascades regulated by α2-chn remain poorly understood. Here, we demonstrate that several cytoskeletal regulatory proteins-collapsin response mediator protein 2 (CRMP2; encoded by the gene dpysl2), stathmin1, and stathmin 2-bind to α2-CHN. dpysl2, stathmin1, and especially stathmin2 are expressed by ocular motor neurons. We find that the manipulation of dpysl2 and of stathmins in zebrafish larvae leads to defects in both the axon wiring of the ocular motor system and the optokinetic reflex, impairing horizontal eye movements. Knockdowns of these molecules in zebrafish larvae of either sex caused axon guidance phenotypes that included defasciculation and ectopic branching; in some cases, these phenotypes were reminiscent of DRS. chn1 knock-down phenotypes were rescued by the overexpression of CRMP2 and STMN1, suggesting that these proteins act in the same signaling pathway. These findings suggest that CRMP2 and stathmins signal downstream of α2-CHN to orchestrate ocular motor axon guidance and to control eye movements.SIGNIFICANCE STATEMENT The precise control of eye movements is crucial for the life of vertebrate animals, including humans. In humans, this control depends on the arrangement of nerve wiring of the ocular motor system, composed of three nerves and six muscles, a system that is conserved across vertebrate phyla. Mutations in the protein alpha2-chimaerin have previously been shown to cause eye movement disorders (squint) and axon wiring defects in humans. Our recent work has unraveled how alpha2-chimaerin coordinates axon guidance of the ocular motor system in animal models. In this article, we demonstrate key roles for the proteins CRMP2 and stathmin 1/2 in the signaling pathway orchestrated by alpha2-chimaerin, potentially giving insight into the etiology of eye movement disorders in humans.
Collapse
Affiliation(s)
| | | | - Ivana Poparic
- Department of Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | | | - Mary Chol
- Department of Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Isaac H Bianco
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Marco Chiapello
- Cambridge Centre for Proteomics, Cambridge Systems Biology Centre, Department of Biochemistry, University of Cambridge, Cambridge CB2 1QR, United Kingdom
| | - Renata Feret
- Institute for Sustainable Plant Protection, National Research Council, 10135 Torino, Italy
| | - Michael J Deery
- Institute for Sustainable Plant Protection, National Research Council, 10135 Torino, Italy
| | - Sarah Guthrie
- School of Life Sciences, University of Sussex, Brighton BN7 9QG, United Kingdom
| |
Collapse
|
2
|
Lv L, Liu Y, Xie J, Wu Y, Zhao J, Li Q, Zhong Y. Interplay between α2-chimaerin and Rac1 activity determines dynamic maintenance of long-term memory. Nat Commun 2019; 10:5313. [PMID: 31757963 PMCID: PMC6876637 DOI: 10.1038/s41467-019-13236-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 10/22/2019] [Indexed: 12/05/2022] Open
Abstract
Memory consolidation theory suggests that once memory formation has been completed, memory is maintained at a stable strength and is incapable of further enhancement. However, the current study reveals that even long after formation, contextual fear memory could be further enhanced. Such unexpected enhancement is possible because memory is dynamically maintained at an intermediate level that allows for bidirectional regulation. Here we find that both Rac1 activation and expression of α2-chimaerin are stimulated by single-trial contextual fear conditioning. Such sustained Rac1 activity mediates reversible forgetting, and α2-chimaerin acts as a memory molecule that reverses forgetting to sustain memory through inhibition of Rac1 activity during the maintenance stage. Therefore, the balance between activated Rac1 and expressed α2-chimaerin defines dynamic long-term memory maintenance. Our findings demonstrate that consolidated memory maintains capacity for bidirectional regulation.
Collapse
Affiliation(s)
- Li Lv
- Peking University-Tsinghua University-National Institute Biological Science Joint Graduate Program, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yunlong Liu
- Peking University-Tsinghua University-National Institute Biological Science Joint Graduate Program, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianxin Xie
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100101, China
| | - Yan Wu
- Peking University-Tsinghua University-National Institute Biological Science Joint Graduate Program, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianjian Zhao
- Peking University-Tsinghua University-National Institute Biological Science Joint Graduate Program, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qian Li
- Peking University-Tsinghua University-National Institute Biological Science Joint Graduate Program, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yi Zhong
- Peking University-Tsinghua University-National Institute Biological Science Joint Graduate Program, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| |
Collapse
|
3
|
Nugent AA, Park JG, Wei Y, Tenney AP, Gilette NM, DeLisle MM, Chan WM, Cheng L, Engle EC. Mutant α2-chimaerin signals via bidirectional ephrin pathways in Duane retraction syndrome. J Clin Invest 2017; 127:1664-1682. [PMID: 28346224 DOI: 10.1172/jci88502] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 02/02/2017] [Indexed: 01/18/2023] Open
Abstract
Duane retraction syndrome (DRS) is the most common form of congenital paralytic strabismus in humans and can result from α2-chimaerin (CHN1) missense mutations. We report a knockin α2-chimaerin mouse (Chn1KI/KI) that models DRS. Whole embryo imaging of Chn1KI/KI mice revealed stalled abducens nerve growth and selective trochlear and first cervical spinal nerve guidance abnormalities. Stalled abducens nerve bundles did not reach the orbit, resulting in secondary aberrant misinnervation of the lateral rectus muscle by the oculomotor nerve. By contrast, Chn1KO/KO mice did not have DRS, and embryos displayed abducens nerve wandering distinct from the Chn1KI/KI phenotype. Murine embryos lacking EPH receptor A4 (Epha4KO/KO), which is upstream of α2-chimaerin in corticospinal neurons, exhibited similar abducens wandering that paralleled previously reported gait alterations in Chn1KO/KO and Epha4KO/KO adult mice. Findings from Chn1KI/KI Epha4KO/KO mice demonstrated that mutant α2-chimaerin and EphA4 have different genetic interactions in distinct motor neuron pools: abducens neurons use bidirectional ephrin signaling via mutant α2-chimaerin to direct growth, while cervical spinal neurons use only ephrin forward signaling, and trochlear neurons do not use ephrin signaling. These findings reveal a role for ephrin bidirectional signaling upstream of mutant α2-chimaerin in DRS, which may contribute to the selective vulnerability of abducens motor neurons in this disorder.
Collapse
|
4
|
Zhuang X, Sun F, Li L, Jiang D, Li X, Sun A, Pan Z, Lou N, Zhang L, Lou F. Therapeutic Effect of Metformin on Chemerin in Non-Obese Patients with Non-Alcoholic Fatty Liver Disease (NAFLD). Clin Lab 2015; 61:1409-14. [PMID: 26642701 DOI: 10.7754/clin.lab.2015.150211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Chemerin is an important risk factor of insulin resistance. Non-alcoholic fatty liver has typical characteristics of insulin resistance. The aim of this study was to explore the potential role of chemerin in NAFLD. METHODS 45 subjects included 22 control subjects (A group) and 23 subjects diagnosed with non-alcoholic fatty liver disease (B group) participated in the study. 23 patients in the NAFLD group received oral daily metformin at a dose of 20 mg/kg/day for 24 weeks follow-up. Chemerin and insulin resistance markers were determined at baseline and 24 weeks. RESULTS The levels of WHR, BMI, FINS, HOMA-IR, TG, ALT, AST, and Chemerin in B group were significantly higher than A group. After 24 weeks of metformin treatment, the levels of WHR, AST, ALT, TG, chemerin and HOMA-IR were significantly reduced (p < 0.05) and other indexes were not changed significantly. Correlation analysis indicated that serum chemerin concentrations were positively correlated with BMI, WHR, HOMA-IR, FINS, TG, ALT, and AST levels. Logistic regression analysis showed chemerin, TG, and ALT were independent variables associated with NAFLD. CONCLUSIONS These findings showed a significant increase of chemerin level in NAFLD patients. Metformin treatment can improve NAFLD and decrease the level of chemerin. Chemerin, TG, and ALT were independent variables associated with NAFLD.
Collapse
|
5
|
Miyake N, Chilton J, Psatha M, Cheng L, Andrews C, Chan WM, Law K, Crosier M, Lindsay S, Cheung M, Allen J, Gutowski NJ, Ellard S, Young E, Iannaccone A, Appukuttan B, Stout JT, Christiansen S, Ciccarelli ML, Baldi A, Campioni M, Zenteno JC, Davenport D, Mariani LE, Sahin M, Guthrie S, Engle EC. Human CHN1 mutations hyperactivate alpha2-chimaerin and cause Duane's retraction syndrome. Science 2008; 321:839-43. [PMID: 18653847 PMCID: PMC2593867 DOI: 10.1126/science.1156121] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Duane's retraction syndrome (DRS) is a complex congenital eye movement disorder caused by aberrant innervation of the extraocular muscles by axons of brainstem motor neurons. Studying families with a variant form of the disorder (DURS2-DRS), we have identified causative heterozygous missense mutations in CHN1, a gene on chromosome 2q31 that encodes alpha2-chimaerin, a Rac guanosine triphosphatase-activating protein (RacGAP) signaling protein previously implicated in the pathfinding of corticospinal axons in mice. We found that these are gain-of-function mutations that increase alpha2-chimaerin RacGAP activity in vitro. Several of the mutations appeared to enhance alpha2-chimaerin translocation to the cell membrane or enhance its ability to self-associate. Expression of mutant alpha2-chimaerin constructs in chick embryos resulted in failure of oculomotor axons to innervate their target extraocular muscles. We conclude that alpha2-chimaerin has a critical developmental function in ocular motor axon pathfinding.
Collapse
Affiliation(s)
- Noriko Miyake
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - John Chilton
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Research Way, Plymouth PL6 8BU, UK
| | - Maria Psatha
- MRC Centre for Developmental Neurobiology, King's College, Guy's Campus, London SE1 1UL, UK
| | - Long Cheng
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Caroline Andrews
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115, USA
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Wai-Man Chan
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115, USA
| | - Krystal Law
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115, USA
| | - Moira Crosier
- MRC-Wellcome Trust Human Developmental Biology Resource (Newcastle), Institute of Human Genetics, Newcastle University, International Centre for Life, Newcastle upon Tyne, NE1 3BZ, UK
| | - Susan Lindsay
- MRC-Wellcome Trust Human Developmental Biology Resource (Newcastle), Institute of Human Genetics, Newcastle University, International Centre for Life, Newcastle upon Tyne, NE1 3BZ, UK
| | - Michelle Cheung
- MRC Centre for Developmental Neurobiology, King's College, Guy's Campus, London SE1 1UL, UK
| | - James Allen
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Research Way, Plymouth PL6 8BU, UK
| | - Nick J Gutowski
- Department of Neurology, Royal Devon and Exeter Hospital, Barrack Road, Exeter, Devon, EX2 5DW, UK
- Peninsula Medical School, Barrack Road, Exeter EX2 5DW, UK
| | - Sian Ellard
- Department of Molecular Genetics, Royal Devon and Exeter Hospital, Barrack Road, Exeter, Devon, EX2 5DW, UK
- Peninsula Medical School, Barrack Road, Exeter EX2 5DW, UK
| | | | - Alessandro Iannaccone
- University of Tennessee Health Science Center, Hamilton Eye Institute, 930 Madison Avenue, Suite 731, Memphis, TN 38163, USA
| | - Binoy Appukuttan
- Casey Eye Institute, Oregon Health and Science University, 3375 SW Terwilliger Blvd, Portland, OR 97239, USA
| | - J. Timothy Stout
- Casey Eye Institute, Oregon Health and Science University, 3375 SW Terwilliger Blvd, Portland, OR 97239, USA
| | - Stephen Christiansen
- Department of Ophthalmology, University of Minnesota, MMC 493, 420 Delaware St, SE, Minneapolis, MN 55455-0501, USA
| | | | - Alfonso Baldi
- Department of Biochemistry 'F. Cedrangolo', Section of Pathologic Anatomy, Second University of Naples, Naples, Italy
| | - Mara Campioni
- Department of Biochemistry 'F. Cedrangolo', Section of Pathologic Anatomy, Second University of Naples, Naples, Italy
| | - Juan C. Zenteno
- Department of Genetics and Research Unit, Institute of Ophthalmology “Conde de Valenciana”, Mexico City, Mexico
| | - Dominic Davenport
- MRC Centre for Developmental Neurobiology, King's College, Guy's Campus, London SE1 1UL, UK
| | - Laura E. Mariani
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115, USA
| | - Mustafa Sahin
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Sarah Guthrie
- MRC Centre for Developmental Neurobiology, King's College, Guy's Campus, London SE1 1UL, UK
| | - Elizabeth C. Engle
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115, USA
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115, USA
- Department of Ophthalmology, Children’s Hospital Boston, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| |
Collapse
|
6
|
Fawcett JP, Georgiou J, Ruston J, Bladt F, Sherman A, Warner N, Saab BJ, Scott R, Roder JC, Pawson T. Nck adaptor proteins control the organization of neuronal circuits important for walking. Proc Natl Acad Sci U S A 2007; 104:20973-8. [PMID: 18093944 PMCID: PMC2409251 DOI: 10.1073/pnas.0710316105] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Indexed: 01/15/2023] Open
Abstract
The intracellular signaling targets used by mammalian axon guidance receptors to organize the nervous system in vivo are unclear. The Nck1 and Nck2 SH2/SH3 adaptors (collectively Nck) can couple phosphotyrosine (pTyr) signals to reorganization of the actin cytoskeleton and are therefore candidates for linking guidance cues to the regulatory machinery of the cytoskeleton. We find that selective inactivation of Nck in the murine nervous system causes a hopping gait and a defect in the spinal central pattern generator, which is characterized by synchronous firing of bilateral ventral motor neurons. Nck-deficient mice also show abnormal projections of corticospinal tract axons and defective development of the posterior tract of the anterior commissure. These phenotypes are consistent with a role for Nck in signaling initiated by different classes of guidance receptors, including the EphA4 receptor tyrosine kinase. Our data indicate that Nck adaptors couple pTyr guidance signals to cytoskeletal events required for the ipsilateral projections of spinal cord neurons and thus for normal limb movement.
Collapse
Affiliation(s)
- James P. Fawcett
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
- Departments of Pharmacology and Surgery, Dalhousie University, 5850 College Street, Halifax, NS, Canada B3H 1X5
| | - John Georgiou
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
| | - Julie Ruston
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
| | - Friedhelm Bladt
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
| | - Andrew Sherman
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8; and
| | - Neil Warner
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8; and
| | - Bechara J. Saab
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8; and
| | - Rizaldy Scott
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
| | - John C. Roder
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8; and
| | - Tony Pawson
- *Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8; and
| |
Collapse
|
7
|
Beg AA, Sommer JE, Martin JH, Scheiffele P. alpha2-Chimaerin is an essential EphA4 effector in the assembly of neuronal locomotor circuits. Neuron 2007; 55:768-78. [PMID: 17785183 DOI: 10.1016/j.neuron.2007.07.036] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 07/23/2007] [Accepted: 07/31/2007] [Indexed: 10/22/2022]
Abstract
The assembly of neuronal networks during development requires tightly controlled cell-cell interactions. Multiple cell surface receptors that control axon guidance and synapse maturation have been identified. However, the signaling mechanisms downstream of these receptors have remained unclear. Receptor signals might be transmitted through dedicated signaling lines defined by specific effector proteins. Alternatively, a single cell surface receptor might couple to multiple effectors with overlapping functions. We identified the neuronal RacGAP alpha2-chimaerin as an effector for the receptor tyrosine kinase EphA4. alpha2-Chimaerin interacts with activated EphA4 and is required for ephrin-induced growth cone collapse in cortical neurons. alpha2-Chimaerin mutant mice exhibit a rabbit-like hopping gait with synchronous hindlimb movements that phenocopies mice lacking EphA4 kinase activity. Anatomical and functional analyses of corticospinal and spinal interneuron projections reveal that loss of alpha2-chimaerin results in impairment of EphA4 signaling in vivo. These findings identify alpha2-chimaerin as an indispensable effector for EphA4 in cortical and spinal motor circuits.
Collapse
Affiliation(s)
- Asim A Beg
- Department of Physiology and Cellular Biophysics, Department of Neuroscience, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA
| | | | | | | |
Collapse
|
8
|
Abstract
In two manuscripts published in Neuron (Beg et al. and Wegmeyer et al.) and one published in Cell (Iwasato et al.), investigators have found that a particular GAP, alpha-chimaerin, is required in vivo for ephrinB3/EphA4-dependent motor circuit formation.
Collapse
Affiliation(s)
- Matthew B Dalva
- Department of Neuroscience, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA.
| |
Collapse
|
9
|
Iwasato T, Katoh H, Nishimaru H, Ishikawa Y, Inoue H, Saito YM, Ando R, Iwama M, Takahashi R, Negishi M, Itohara S. Rac-GAP alpha-chimerin regulates motor-circuit formation as a key mediator of EphrinB3/EphA4 forward signaling. Cell 2007; 130:742-53. [PMID: 17719550 DOI: 10.1016/j.cell.2007.07.022] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 05/24/2007] [Accepted: 07/16/2007] [Indexed: 11/16/2022]
Abstract
The ephrin/Eph system plays a central role in neuronal circuit formation; however, its downstream effectors are poorly understood. Here we show that alpha-chimerin Rac GTPase-activating protein mediates ephrinB3/EphA4 forward signaling. We discovered a spontaneous mouse mutation, miffy (mfy), which results in a rabbit-like hopping gait, impaired corticospinal axon guidance, and abnormal spinal central pattern generators. Using positional cloning, transgene rescue, and gene targeting, we demonstrated that loss of alpha-chimerin leads to mfy phenotypes similar to those of EphA4(-/-) and ephrinB3(-/-) mice. alpha-chimerin interacts with EphA4 and, in response to ephrinB3/EphA4 signaling, inactivates Rac, which is a positive regulator of process outgrowth. Moreover, downregulation of alpha-chimerin suppresses ephrinB3-induced growth cone collapse in cultured neurons. Our findings indicate that ephrinB3/EphA4 signaling prevents growth cone extension in motor circuit formation via alpha-chimerin-induced inactivation of Rac. They also highlight the role of a Rho family GTPase-activating protein as a key mediator of ephrin/Eph signaling.
Collapse
MESH Headings
- Animals
- Animals, Newborn
- Cells, Cultured
- Cerebral Cortex/cytology
- Chimerin 1/metabolism
- Chromosomes, Mammalian
- Crosses, Genetic
- Ephrin-B3/genetics
- Ephrin-B3/metabolism
- Genes, Recessive
- Genetic Linkage
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Knockout
- Mice, Transgenic
- Molecular Sequence Data
- Motor Activity/genetics
- Mutation
- N-Methylaspartate/pharmacology
- Neurons/cytology
- Neurons/metabolism
- Polymorphism, Single Nucleotide
- Serotonin/pharmacology
- Signal Transduction
- Spinal Cord/drug effects
- rac GTP-Binding Proteins/physiology
Collapse
Affiliation(s)
- Takuji Iwasato
- Laboratory for Behavioral Genetics, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa Wako-shi, Saitama 351-0198, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Shi L, Fu WY, Hung KW, Porchetta C, Hall C, Fu AKY, Ip NY. Alpha2-chimaerin interacts with EphA4 and regulates EphA4-dependent growth cone collapse. Proc Natl Acad Sci U S A 2007; 104:16347-52. [PMID: 17911252 PMCID: PMC2042209 DOI: 10.1073/pnas.0706626104] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
EphA4-dependent growth cone collapse requires reorganization of actin cytoskeleton through coordinated activation of Rho family GTPases. Whereas various guanine exchange factors have recently been identified to be involved in EphA4-mediated regulation of Rho GTPases and growth cone collapse, the functional roles of GTPase-activating proteins in the process are largely unknown. Here we report that EphA4 interacts with alpha2-chimaerin through its Src homology 2 domain. Activated EphA4 induces a rapid increase of tyrosine phosphorylation of alpha2-chimaerin and enhances its GTPase-activating protein activity toward Rac1. More importantly, alpha2-chimaerin regulates the action of EphA4 in growth cone collapse through modulation of Rac1 activity. Our findings have therefore identified a new alpha2-chimaerin-dependent signaling mechanism through which EphA4 transduces its signals to the actin cytoskeleton and modulates growth cone morphology.
Collapse
Affiliation(s)
- Lei Shi
- *Department of Biochemistry, Biotechnology Research Institute, and Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; and
| | - Wing-Yu Fu
- *Department of Biochemistry, Biotechnology Research Institute, and Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; and
| | - Kwok-Wang Hung
- *Department of Biochemistry, Biotechnology Research Institute, and Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; and
| | - Cassandra Porchetta
- Department of Molecular Neuroscience, Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, United Kingdom
| | - Christine Hall
- Department of Molecular Neuroscience, Institute of Neurology, University College London, 1 Wakefield Street, London WC1N 1PJ, United Kingdom
| | - Amy K. Y. Fu
- *Department of Biochemistry, Biotechnology Research Institute, and Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; and
| | - Nancy Y. Ip
- *Department of Biochemistry, Biotechnology Research Institute, and Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; and
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
11
|
Wegmeyer H, Egea J, Rabe N, Gezelius H, Filosa A, Enjin A, Varoqueaux F, Deininger K, Schnütgen F, Brose N, Klein R, Kullander K, Betz A. EphA4-Dependent Axon Guidance Is Mediated by the RacGAP α2-Chimaerin. Neuron 2007; 55:756-67. [PMID: 17785182 DOI: 10.1016/j.neuron.2007.07.038] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 07/20/2007] [Accepted: 07/30/2007] [Indexed: 01/19/2023]
Abstract
Neuronal network formation in the developing nervous system is dependent on the accurate navigation of nerve cell axons and dendrites, which is controlled by attractive and repulsive guidance cues. Ephrins and their cognate Eph receptors mediate many repulsive axonal guidance decisions by intercellular interactions resulting in growth cone collapse and axon retraction of the Eph-presenting neuron. We show that the Rac-specific GTPase-activating protein alpha2-chimaerin binds activated EphA4 and mediates EphA4-triggered axonal growth cone collapse. alpha-Chimaerin mutant mice display a phenotype similar to that of EphA4 mutant mice, including aberrant midline axon guidance and defective spinal cord central pattern generator activity. Our results reveal an alpha-chimaerin-dependent signaling pathway downstream of EphA4, which is essential for axon guidance decisions and neuronal circuit formation in vivo.
Collapse
Affiliation(s)
- Heike Wegmeyer
- Department of Molecular Neurobiology and DFG Center for Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Van de Ven TJ, VanDongen HMA, VanDongen AMJ. The nonkinase phorbol ester receptor alpha 1-chimerin binds the NMDA receptor NR2A subunit and regulates dendritic spine density. J Neurosci 2006; 25:9488-96. [PMID: 16221859 PMCID: PMC6725706 DOI: 10.1523/jneurosci.2450-05.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Abnormalities in dendritic spines have long been associated with cognitive dysfunction and neurodevelopmental delay, whereas rapid changes in spine shape underlie synaptic plasticity. The key regulators of cytoskeletal reorganization in dendrites and spines are the Rho GTPases, which modify actin polymerization in response to synaptic signaling. Rho GTPase activity is modulated by multiple regulatory proteins, some of which have been found to associate with proteins localized to spines. Here, we show that the nonkinase phorbol ester receptor alpha1-chimerin is present in dendrites and spines, where it binds to the NMDA receptor NR2A subunit in a phorbol ester-dependent manner. Alpha1-chimerin contains a GTPase activating (GAP) domain, with activity toward the Rho family member Rac1. Overexpression of alpha1-chimerin in cultured hippocampal neurons inhibits formation of new spines and removes existing spines. This reduction in spine density is mediated by Rac1 inhibition, because it depends critically on the presence of a functional GAP domain. Conversely, depletion of alpha1-chimerin leads to an increase in spine density, indicating that a basal inhibition of Rac1 maintains the number of spines at a submaximal level. The ability of alpha1-chimerin to modulate spine number requires an interaction with the NMDA receptor, because an alpha1-chimerin mutant that binds weakly to NR2A fails to decrease spine density. Together, these results suggest that alpha1-chimerin is able to modulate dendritic spine morphology by binding to synaptic NMDA receptors and locally inactivating Rac1.
Collapse
Affiliation(s)
- Thomas J Van de Ven
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | | | | |
Collapse
|
13
|
Buttery P, Beg AA, Chih B, Broder A, Mason CA, Scheiffele P. The diacylglycerol-binding protein alpha1-chimaerin regulates dendritic morphology. Proc Natl Acad Sci U S A 2006; 103:1924-9. [PMID: 16446429 PMCID: PMC1413663 DOI: 10.1073/pnas.0510655103] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The morphological and functional differentiation of neuronal dendrites is controlled through transcriptional programs and cell-cell signaling. Synaptic activity is thought to play an important role in the maturation of dendritic arbors, but the signaling pathways that couple neuronal activity and morphological changes in dendrites are not well understood. We explored the function of alpha1-chimaerin, a neuronal diacylglycerol-binding protein with a Rho GTPase-activating protein domain that inactivates Rac1. We find that stimulation of phospholipase Cbeta-coupled cell surface receptors recruits alpha1-chimaerin to the plasma membrane of cultured hippocampal neurons. We further show that alpha1-chimaerin protein levels are controlled by synaptic activity and that increased alpha1-chimaerin expression results in the pruning of dendritic spines and branches. This pruning activity requires both the diacylglycerol-binding and Rac GTPase-activating protein activity of alpha1-chimaerin. Suppression of alpha1-chimaerin expression resulted in increased process growth from the dendritic shaft and from spine heads. Our data suggest that alpha1-chimaerin is an activity-regulated Rho GTPase regulator that is activated by phospholipase Cbeta-coupled cell surface receptors and contributes to pruning of dendritic arbors.
Collapse
Affiliation(s)
- Philip Buttery
- *Department of Pathology and Cell Biology, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, P&S 14-509, 630 West 168th Street, New York, NY 10032; and
| | - Asim A. Beg
- Department of Physiology and Cellular Biophysics, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, P&S 11-511, 630 West 168th Street, New York, NY 10032
| | - Ben Chih
- Department of Physiology and Cellular Biophysics, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, P&S 11-511, 630 West 168th Street, New York, NY 10032
| | - Arkady Broder
- Department of Physiology and Cellular Biophysics, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, P&S 11-511, 630 West 168th Street, New York, NY 10032
| | - Carol A. Mason
- *Department of Pathology and Cell Biology, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, P&S 14-509, 630 West 168th Street, New York, NY 10032; and
| | - Peter Scheiffele
- Department of Physiology and Cellular Biophysics, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, P&S 11-511, 630 West 168th Street, New York, NY 10032
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
14
|
Brown M, Jacobs T, Eickholt B, Ferrari G, Teo M, Monfries C, Qi RZ, Leung T, Lim L, Hall C. Alpha2-chimaerin, cyclin-dependent Kinase 5/p35, and its target collapsin response mediator protein-2 are essential components in semaphorin 3A-induced growth-cone collapse. J Neurosci 2005; 24:8994-9004. [PMID: 15483118 PMCID: PMC6730050 DOI: 10.1523/jneurosci.3184-04.2004] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurite outgrowth is influenced by positive and negative signals that include the semaphorins, an important family of axonal outgrowth inhibitors. Here we report that the Rac GTPase activating protein (GAP)alpha2-chimaerin is involved in Semaphorin 3A (Sema 3A) signaling. In dorsal root ganglion neurons, Sema 3A-induced growth cone collapse was inhibited by alpha2-chimaerin mutated to eliminate GAP activity or interaction with phosphotyrosine. Activation of alpha2-chimaerin by phorbol ester caused growth cone collapse. Active alpha2-chimaerin interacts with collapsin response mediator protein-2 (CRMP-2) and cyclin-dependent kinase (Cdk) 5/p35 kinase through its SH2 and GAP domains, respectively. Cdk5 phosphorylates CRMP-2 at serine 522, possibly facilitating phosphorylation of serine 518 and threonine 514 by glycogen synthase kinase 3beta (GSK3beta), a kinase previously implicated in Sema 3A signaling. Phosphorylation of CRMP-2 serine 522 was essential for Sema 3A-induced growth cone collapse, which is dependent on Cdk5 but not Rho kinase activity. alpha2-chimaerin, like CRMP-2, can associate with the Sema 3A receptor. These results indicate that active alpha2-chimaerin Rac GAP, Cdk5/p35, and its substrate CRMP-2, are implicated in the dynamics of growth cone guidance initiated through Sema 3A signaling.
Collapse
Affiliation(s)
- Matthew Brown
- Department of Molecular Neuroscience, Institute of Neurology, University College London, London WC1N 1PJ, United Kingdom
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Qi RZ, Ching YP, Kung HF, Wang JH. Alpha-chimaerin exists in a functional complex with the Cdk5 kinase in brain. FEBS Lett 2004; 561:177-80. [PMID: 15013773 DOI: 10.1016/s0014-5793(04)00174-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 01/07/2004] [Accepted: 01/08/2004] [Indexed: 10/26/2022]
Abstract
Cyclin-dependent kinase 5 (Cdk5) in association with its neuronal activators p35 and p39 shows a complex involvement in the control of neurocytoskeletal dynamics. Here we show that alpha-chimaerin, a GTPase-activating protein specific for Rac and Cdc42, is a p35-binding protein. The interaction domains of p35 and alpha-chimaerin were delineated. In transfected HeLa cells, p35 and alpha-chimaerin displayed an overlapping distribution pattern and they could be co-immunoprecipitated from the cell lysate. As alpha-chimaerin has a regulatory function in actin repolymerization, these results suggested that the regulation of neurocytoskeleton dynamics by Cdk5 is mediated at least in part via alpha-chimaerin.
Collapse
Affiliation(s)
- Robert Z Qi
- Institute of Molecular Biology, University of Hong Kong, Pokfulam, Hong Kong
| | | | | | | |
Collapse
|
16
|
Lee DJ, Cox D, Li J, Greenberg S. Rac1 and Cdc42 are required for phagocytosis, but not NF-kappaB-dependent gene expression, in macrophages challenged with Pseudomonas aeruginosa. J Biol Chem 2000; 275:141-6. [PMID: 10617597 DOI: 10.1074/jbc.275.1.141] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Macrophages respond to Gram-negative bacterial pathogens by phagocytosis and pro-inflammatory gene expression. These responses may require GTPases that have been implicated in cytoskeletal alterations and activation of NF-kappaB. To determine the role of Rac1 and Cdc42 in signal transduction events triggered by Pseudomonas aeruginosa, we expressed GTP binding-deficient alleles of Rac1 or Cdc42, or Chim-GAP, a Rac1/Cdc42-specific GTPase-activating protein domain, in a subline of RAW 264.7 cells, and challenged the transfected cells with a laboratory strain of P. aeruginosa, PAO1. Expression of Rac1 N17, Cdc42 N17, or Chim-GAP led to a marked reduction of phagocytosis. In contrast, nuclear translocation of p65 NF-kappaB was unaffected by expression of the same constructs. Incubation of macrophages with PAO1 led to NF-kappaB-dependent expression of inducible nitric-oxide synthase, COX-2, and tumor necrosis factor-alpha, which was unaffected by inhibition of Rac1 or Cdc42 function. Isogenic strains of PAO1 that lacked surface adhesins were poorly ingested; however, they induced pro-inflammatory gene expression with an efficiency equal to that of PAO1. These results indicate that the signal transduction events leading to phagocytosis and pro-inflammatory protein expression are distinct. Rac1 and Cdc42 serve as effectors of phagocytosis, but not NF-kappaB-dependent gene expression, in the macrophage response to P. aeruginosa.
Collapse
Affiliation(s)
- D J Lee
- Department of Pediatrics, Columbia University, New York, New York 10032, USA
| | | | | | | |
Collapse
|