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Wang LM, Kuhl E. Mechanics of axon growth and damage: A systematic review of computational models. Semin Cell Dev Biol 2023; 140:13-21. [PMID: 35474150 DOI: 10.1016/j.semcdb.2022.04.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 04/12/2022] [Accepted: 04/19/2022] [Indexed: 01/28/2023]
Abstract
Normal axon development depends on the action of mechanical forces both generated within the cytoskeleton and outside the cell, but forces of large magnitude or rate cause damage instead. Computational models aid scientists in studying the role of mechanical forces in axon growth and damage. These studies use simulations to evaluate how different sources of force generation within the cytoskeleton interact with each other to regulate axon elongation and retraction. Furthermore, mathematical models can help optimize externally applied tension to promote axon growth without causing damage. Finally, scientists also use simulations of axon damage to investigate how forces are distributed among different components of the axon and how the tissue surrounding an axon influences its susceptibility to injury. In this review, we discuss how computational studies complement experimental studies in the areas of axon growth, regeneration, and damage.
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Affiliation(s)
- Lucy M Wang
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
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2
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Schneider F, Metz I, Rust MB. Regulation of actin filament assembly and disassembly in growth cone motility and axon guidance. Brain Res Bull 2023; 192:21-35. [PMID: 36336143 DOI: 10.1016/j.brainresbull.2022.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
Directed outgrowth of axons is fundamental for the establishment of neuronal networks. Axon outgrowth is guided by growth cones, highly motile structures enriched in filamentous actin (F-actin) located at the axons' distal tips. Growth cones exploit F-actin-based protrusions to scan the environment for guidance cues, and they contain the sensory apparatus to translate guidance cue information into intracellular signaling cascades. These cascades act upstream of actin-binding proteins (ABP) and thereby control assembly and disassembly of F-actin. Spatiotemporally controlled F-actin dis-/assembly in growth cones steers the axon towards attractants and away from repellents, and it thereby navigates the axon through the developing nervous system. Hence, ABP that control F-actin dynamics emerged as critical regulators of neuronal network formation. In the present review article, we will summarize and discuss current knowledge of the mechanisms that control remodeling of the actin cytoskeleton in growth cones, focusing on recent progress in the field. Further, we will introduce tools and techniques that allow to study actin regulatory mechanism in growth cones.
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Affiliation(s)
- Felix Schneider
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany; Molecular Urooncology, Department of Urology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Isabell Metz
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Marco B Rust
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University Giessen, 35032 Marburg, Germany.
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3
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Buscaglia G, Northington KR, Aiken J, Hoff KJ, Bates EA. Bridging the Gap: The Importance of TUBA1A α-Tubulin in Forming Midline Commissures. Front Cell Dev Biol 2022; 9:789438. [PMID: 35127710 PMCID: PMC8807549 DOI: 10.3389/fcell.2021.789438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Developing neurons undergo dramatic morphological changes to appropriately migrate and extend axons to make synaptic connections. The microtubule cytoskeleton, made of α/β-tubulin dimers, drives neurite outgrowth, promotes neuronal growth cone responses, and facilitates intracellular transport of critical cargoes during neurodevelopment. TUBA1A constitutes the majority of α-tubulin in the developing brain and mutations to TUBA1A in humans cause severe brain malformations accompanied by varying neurological defects, collectively termed tubulinopathies. Studies of TUBA1A function in mammalian cells have been limited by the presence of multiple genes encoding highly similar tubulin proteins, which leads to α-tubulin antibody promiscuity and makes genetic manipulation challenging. Here, we test mutant tubulin levels and assembly activity and analyze the impact of TUBA1A reduction on growth cone composition, neurite extension, and commissural axon architecture during brain development. We present a novel tagging method for studying and manipulating TUBA1A in cells without impairing tubulin function. Using this tool, we show that a TUBA1A loss-of-function mutation TUBA1A N102D (TUBA1A ND ), reduces TUBA1A protein levels and prevents incorporation of TUBA1A into microtubule polymers. Reduced Tuba1a α-tubulin in heterozygous Tuba1a ND/+ mice leads to grossly normal brain formation except a significant impact on axon extension and impaired formation of forebrain commissures. Neurons with reduced Tuba1a as a result of the Tuba1a ND mutation exhibit slower neuron outgrowth compared to controls. Neurons deficient in Tuba1a failed to localize microtubule associated protein-1b (Map1b) to the developing growth cone, likely impacting stabilization of microtubules. Overall, we show that reduced Tuba1a is sufficient to support neuronal migration and cortex development but not commissure formation, and provide mechanistic insight as to how TUBA1A tunes microtubule function to support neurodevelopment.
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Affiliation(s)
- Georgia Buscaglia
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Kyle R. Northington
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jayne Aiken
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Katelyn J. Hoff
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Emily A. Bates
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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Gamarra M, de la Cruz A, Blanco-Urrejola M, Baleriola J. Local Translation in Nervous System Pathologies. Front Integr Neurosci 2021; 15:689208. [PMID: 34276318 PMCID: PMC8279726 DOI: 10.3389/fnint.2021.689208] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/03/2021] [Indexed: 12/13/2022] Open
Abstract
Dendrites and axons can extend dozens to hundreds of centimeters away from the cell body so that a single neuron can sense and respond to thousands of stimuli. Thus, for an accurate function of dendrites and axons the neuronal proteome needs to be asymmetrically distributed within neurons. Protein asymmetry can be achieved by the transport of the protein itself or the transport of the mRNA that is then translated at target sites in neuronal processes. The latter transport mechanism implies local translation of localized mRNAs. The role of local translation in nervous system (NS) development and maintenance is well established, but recently there is growing evidence that this mechanism and its deregulation are also relevant in NS pathologies, including neurodegenerative diseases. For instance, upon pathological signals disease-related proteins can be locally synthesized in dendrites and axons. Locally synthesized proteins can exert their effects at or close to the site of translation, or they can be delivered to distal compartments like the nucleus and induce transcriptional responses that lead to neurodegeneration, nerve regeneration and other cell-wide responses. Relevant key players in the process of local protein synthesis are RNA binding proteins (RBPs), responsible for mRNA transport to neurites. Several neurological and neurodegenerative disorders, including amyotrophic lateral sclerosis or spinal motor atrophy, are characterized by mutations in genes encoding for RBPs and consequently mRNA localization and local translation are impaired. In other diseases changes in the local mRNA repertoire and altered local protein synthesis have been reported. In this review, we will discuss how deregulation of localized translation at different levels can contribute to the development and progression of nervous system pathologies.
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Affiliation(s)
- María Gamarra
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain
| | - Aida de la Cruz
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain
| | - Maite Blanco-Urrejola
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Neurociencias, Universidad del País Vasco (UPV/EHU), Leioa, Spain.,Departamento de Biología Celular e Histología, Universidad del País Vasco (UPV/EHU), Leioa, Spain
| | - Jimena Baleriola
- Laboratory of Local Translation in Neurons and Glia, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Departamento de Biología Celular e Histología, Universidad del País Vasco (UPV/EHU), Leioa, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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Prostaglandin E2 Increases Neurite Length and the Formation of Axonal Loops, and Regulates Cone Turning in Differentiating NE4C Cells Via PKA. Cell Mol Neurobiol 2021; 42:1385-1397. [PMID: 33389417 DOI: 10.1007/s10571-020-01029-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022]
Abstract
Prostaglandin E2 (PGE2) is a membrane-derived lipid signaling molecule important in neuronal development. Abnormal levels of PGE2, due to environmental insults prenatal development, have been linked to brain pathologies. We have previously shown that the addition of PGE2 to neuroectodermal (NE4C) stem cells affects early stages of neuronal differentiation (day 0-8) including increased stem cell motility, accelerated formation of neurospheres, and elevated calcium levels in growth cones. In this study, we further examine whether PGE2 can influence actin-dependent neuronal morphology in later stages (day 8-12) of NE4C cell differentiation. We show that exposure to PGE2 from the initiation of differentiation increased neurite length and the proportion of neurites that formed axonal loops. We also observed changes in the proportion of turning growth cones as the differentiation progressed, with a reduced likelihood of observing turning (or asymmetrical) growth cones on day 8 and increased odds on days 10 and 12. Moreover, we showed for the first time that the observed changes in cytoskeletal morphology were PGE2/PKA dependent. Interestingly, we also found that PGE2 decreased the total protein levels of the actin-bound form of spinophilin and increased levels of unbound PKA-phosphorylated ser94-spinophilin. Hence, we propose that exposure to PGE2 can destabilize the actin cytoskeleton at various stages of neuronal differentiation due to dissociation of ser94-spinophilin causing changes in neuronal morphology.
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Leite SC, Pinto-Costa R, Sousa MM. Actin dynamics in the growth cone: a key player in axon regeneration. Curr Opin Neurobiol 2020; 69:11-18. [PMID: 33359956 DOI: 10.1016/j.conb.2020.11.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 01/01/2023]
Abstract
Neuronal development, maintenance and function depends on the tight regulation of cytoskeleton organization and dynamics. Following injury, adult central nervous system neurons have a limited ability to regenerate and to recapitulate their robust developmental axon growth. This decreased regenerative capacity is set by their inability to establish regeneration-competent growth cones. Growth cones are actin-enriched structures that regulate axon extension rate and direction. During neuronal development, increasing actin dynamics in the growth cone through the regulation of the activity of specific actin-binding proteins leads to increased axon elongation. Here, we will focus on recent findings showing that enhanced axon regeneration in the adult nervous system can be achieved by promoting actin dynamics, or by decreasing actomyosin contraction in the growth cone. These discoveries underscore the importance of actin organization in the growth cone as a key factor to promote axon (re)growth that should be further explored in the future.
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Affiliation(s)
- Sérgio Carvalho Leite
- Institute of Psychiatry and Neurosciences of Paris, INSERM U1266, Université de Paris, 75014 Paris, France
| | - Rita Pinto-Costa
- Nerve Regeneration Group, i3S- Instituto de Investigação e Inovação em Saúde and IBMC- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal
| | - Monica Mendes Sousa
- Nerve Regeneration Group, i3S- Instituto de Investigação e Inovação em Saúde and IBMC- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
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Chen Y, Xu J, Zhang Y, Ma S, Yi W, Liu S, Yu X, Wang J, Chen Y. Coronin 2B regulates dendrite outgrowth by modulating actin dynamics. FEBS Lett 2020; 594:2975-2987. [PMID: 32692409 DOI: 10.1002/1873-3468.13886] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/13/2020] [Accepted: 07/06/2020] [Indexed: 01/31/2023]
Abstract
Cytoskeletal remodeling is indispensable for the development and maintenance of neuronal structures and functions. However, the molecular machinery that controls the balance between actin polymerization and depolymerization during these processes is incompletely understood. Here, we report that coronin 2B, a conserved actin-binding protein, is concentrated at the tips of developing dendrites and that knockdown of coronin 2B inhibits the growth of dendrites. Importantly, coronin 2B interacts with actin and reduces the F-actin/G-actin ratio. Furthermore, the coiled-coil domain of coronin 2B is required for its oligomerization, thus confining coronin 2B to neurite tips. Our findings collectively suggest that coronin 2B is important for promoting dendrite outgrowth by limiting the speed of actin polymerization at growth cones.
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Affiliation(s)
- Yuewen Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science - Shenzhen Fundamental Research Institutions, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China.,Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Jinying Xu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science - Shenzhen Fundamental Research Institutions, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yulin Zhang
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Shuangshuang Ma
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Wanying Yi
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Saijuan Liu
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Xiaojun Yu
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Jiali Wang
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
| | - Yu Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science - Shenzhen Fundamental Research Institutions, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China.,Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, Shenzhen-Hong Kong Institute of Brain Science, HKUST Shenzhen Research Institute, Shenzhen, China
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