1
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Wang W, Rui M. Advances in understanding the roles of actin scaffolding and membrane trafficking in dendrite development. J Genet Genomics 2024:S1673-8527(24)00152-8. [PMID: 38925347 DOI: 10.1016/j.jgg.2024.06.010] [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: 04/24/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 06/28/2024]
Abstract
Dendritic morphology is typically highly branched, and the branching and synaptic abundance of dendrites can enhance the receptive range of neurons and the diversity of information received, thus providing the basis for information processing in the nervous system. Once dendritic development is aberrantly compromised or damaged, it may lead to abnormal connectivity of the neural network, affecting the function and stability of the nervous system and ultimately triggering a series of neurological disorders. Research on the regulation of dendritic developmental processes has flourished, and much progress is now being made in its regulatory mechanisms. Noteworthily, dendrites are characterized by an extremely complex dendritic arborization that cannot be attributed to individual protein functions alone, requiring a systematic analysis of the intrinsic and extrinsic signals and the coordinated roles among them. Actin cytoskeleton organization and membrane vesicle trafficking are required during dendrite development, with actin providing tracks for vesicles and vesicle trafficking in turn providing material for actin assembly. In this review, we focus on these two basic biological processes and discuss the molecular mechanisms and their synergistic effects underlying the morphogenesis of neuronal dendrites. We also offer insights and discuss strategies for the potential preventive and therapeutic treatment of neuropsychiatric disorders.
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Affiliation(s)
- Wanting Wang
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu 210031, China
| | - Menglong Rui
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu 210031, China.
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2
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Mukherjee A, Andrés Jeske Y, Becam I, Taïeb A, Brooks P, Aouad J, Monguillon C, Conduit PT. γ-TuRCs and the augmin complex are required for the development of highly branched dendritic arbors in Drosophila. J Cell Sci 2024; 137:jcs261534. [PMID: 38606636 PMCID: PMC11128279 DOI: 10.1242/jcs.261534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 04/05/2024] [Indexed: 04/13/2024] Open
Abstract
Microtubules are nucleated by γ-tubulin ring complexes (γ-TuRCs) and are essential for neuronal development. Nevertheless, γ-TuRC depletion has been reported to perturb only higher-order branching in elaborated Drosophila larval class IV dendritic arborization (da) neurons. This relatively mild phenotype has been attributed to defects in microtubule nucleation from Golgi outposts, yet most Golgi outposts lack associated γ-TuRCs. By analyzing dendritic arbor regrowth in pupae, we show that γ-TuRCs are also required for the growth and branching of primary and secondary dendrites, as well as for higher-order branching. Moreover, we identify the augmin complex (hereafter augmin), which recruits γ-TuRCs to the sides of pre-existing microtubules, as being required predominantly for higher-order branching. Augmin strongly promotes the anterograde growth of microtubules in terminal dendrites and thus terminal dendrite stability. Consistent with a specific role in higher-order branching, we find that augmin is expressed less strongly and is largely dispensable in larval class I da neurons, which exhibit few higher-order dendrites. Thus, γ-TuRCs are essential for various aspects of complex dendritic arbor development, and they appear to function in higher-order branching via the augmin pathway, which promotes the elaboration of dendritic arbors to help define neuronal morphology.
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Affiliation(s)
- Amrita Mukherjee
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- MRC Toxicology Unit, Gleeson Building, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Yaiza Andrés Jeske
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Isabelle Becam
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Anaelle Taïeb
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Paul Brooks
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Joanna Aouad
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | | | - Paul T. Conduit
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
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3
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Zhang Y, Sung HH, Ziegler AB, Wu YC, Viais R, Sánchez-Huertas C, Kilo L, Agircan FG, Cheng YJ, Mouri K, Uemura T, Lüders J, Chien CT, Tavosanis G. Augmin complex activity finetunes dendrite morphology through non-centrosomal microtubule nucleation in vivo. J Cell Sci 2024; 137:jcs261512. [PMID: 38587100 PMCID: PMC11128282 DOI: 10.1242/jcs.261512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 04/03/2024] [Indexed: 04/09/2024] Open
Abstract
During development, neurons achieve a stereotyped neuron type-specific morphology, which relies on dynamic support by microtubules (MTs). An important player is the augmin complex (hereafter augmin), which binds to existing MT filaments and recruits the γ-tubulin ring complex (γ-TuRC), to form branched MTs. In cultured neurons, augmin is important for neurite formation. However, little is known about the role of augmin during neurite formation in vivo. Here, we have revisited the role of mammalian augmin in culture and then turned towards the class four Drosophila dendritic arborization (c4da) neurons. We show that MT density is maintained through augmin in cooperation with the γ-TuRC in vivo. Mutant c4da neurons show a reduction of newly emerging higher-order dendritic branches and in turn also a reduced number of their characteristic space-filling higher-order branchlets. Taken together, our data reveal a cooperative function for augmin with the γ-TuRC in forming enough MTs needed for the appropriate differentiation of morphologically complex dendrites in vivo.
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Affiliation(s)
- Yun Zhang
- German Center for Neurodegenerative Diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Hsin-Ho Sung
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Anna B. Ziegler
- German Center for Neurodegenerative Diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Ying-Chieh Wu
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Ricardo Viais
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Carlos Sánchez-Huertas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Lukas Kilo
- German Center for Neurodegenerative Diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Fikret Gürkan Agircan
- German Center for Neurodegenerative Diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Kousuke Mouri
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tadashi Uemura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
- Center for Living Systems Information Science, Kyoto University
| | - Jens Lüders
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Gaia Tavosanis
- German Center for Neurodegenerative Diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
- LIMES Institute, University of Bonn, 53115 Bonn, Germany
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4
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Ouzounidis VR, Prevo B, Cheerambathur DK. Sculpting the dendritic landscape: Actin, microtubules, and the art of arborization. Curr Opin Cell Biol 2023; 84:102214. [PMID: 37544207 DOI: 10.1016/j.ceb.2023.102214] [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: 07/06/2022] [Revised: 06/20/2023] [Accepted: 07/05/2023] [Indexed: 08/08/2023]
Abstract
Dendrites are intricately designed neuronal compartments that play a vital role in the gathering and processing of sensory or synaptic inputs. Their diverse and elaborate structures are distinct features of neuronal organization and function. Central to the generation of these dendritic arbors is the neuronal cytoskeleton. In this review, we delve into the current progress toward our understanding of how dendrite arbors are generated and maintained, focusing on the role of the actin and microtubule cytoskeleton.
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Affiliation(s)
- Vasileios R Ouzounidis
- Wellcome Centre for Cell Biology & Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Bram Prevo
- Wellcome Centre for Cell Biology & Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Dhanya K Cheerambathur
- Wellcome Centre for Cell Biology & Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK.
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5
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Nanda S, Bhattacharjee S, Cox DN, Ascoli GA. Local Microtubule and F-Actin Distributions Fully Constrain the Spatial Geometry of Drosophila Sensory Dendritic Arbors. Int J Mol Sci 2023; 24:6741. [PMID: 37047715 PMCID: PMC10095360 DOI: 10.3390/ijms24076741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/29/2023] [Accepted: 04/01/2023] [Indexed: 04/09/2023] Open
Abstract
Dendritic morphology underlies the source and processing of neuronal signal inputs. Morphology can be broadly described by two types of geometric characteristics. The first is dendrogram topology, defined by the length and frequency of the arbor branches; the second is spatial embedding, mainly determined by branch angles and straightness. We have previously demonstrated that microtubules and actin filaments are associated with arbor elongation and branching, fully constraining dendrogram topology. Here, we relate the local distribution of these two primary cytoskeletal components with dendritic spatial embedding. We first reconstruct and analyze 167 sensory neurons from the Drosophila larva encompassing multiple cell classes and genotypes. We observe that branches with a higher microtubule concentration tend to deviate less from the direction of their parent branch across all neuron types. Higher microtubule branches are also overall straighter. F-actin displays a similar effect on angular deviation and branch straightness, but not as consistently across all neuron types as microtubule. These observations raise the question as to whether the associations between cytoskeletal distributions and arbor geometry are sufficient constraints to reproduce type-specific dendritic architecture. Therefore, we create a computational model of dendritic morphology purely constrained by the cytoskeletal composition measured from real neurons. The model quantitatively captures both spatial embedding and dendrogram topology across all tested neuron groups. These results suggest a common developmental mechanism regulating diverse morphologies, where the local cytoskeletal distribution can fully specify the overall emergent geometry of dendritic arbors.
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Affiliation(s)
- Sumit Nanda
- Center for Neural Informatics, Structures, and Plasticity and Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA;
| | - Shatabdi Bhattacharjee
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA; (S.B.); (D.N.C.)
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA; (S.B.); (D.N.C.)
| | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, and Plasticity and Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA;
- Bioengineering Department, College of Engineering and Computing, George Mason University, Fairfax, VA 22032, USA
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6
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Nanda S, Bhattacharjee S, Cox DN, Ascoli GA. Local microtubule and F-actin distributions fully determine the spatial geometry of Drosophila sensory dendritic arbors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.24.529978. [PMID: 36909461 PMCID: PMC10002631 DOI: 10.1101/2023.02.24.529978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Dendritic morphology underlies the source and processing of neuronal signal inputs. Morphology can be broadly described by two types of geometric characteristics. The first is dendrogram topology, defined by the length and frequency of the arbor branches; the second is spatial embedding, mainly determined by branch angles and tortuosity. We have previously demonstrated that microtubules and actin filaments are associated with arbor elongation and branching, fully constraining dendrogram topology. Here we relate the local distribution of these two primary cytoskeletal components with dendritic spatial embedding. We first reconstruct and analyze 167 sensory neurons from the Drosophila larva encompassing multiple cell classes and genotypes. We observe that branches with higher microtubule concentration are overall straighter and tend to deviate less from the direction of their parent branch. F-actin displays a similar effect on the angular deviation from the parent branch direction, but its influence on branch tortuosity varies by class and genotype. We then create a computational model of dendritic morphology purely constrained by the cytoskeletal composition imaged from real neurons. The model quantitatively captures both spatial embedding and dendrogram topology across all tested neuron groups. These results suggest a common developmental mechanism regulating diverse morphologies, where the local cytoskeletal distribution can fully specify the overall emergent geometry of dendritic arbors.
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7
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Bhattacharjee S, Lottes EN, Nanda S, Golshir A, Patel AA, Ascoli GA, Cox DN. PP2A phosphatase regulates cell-type specific cytoskeletal organization to drive dendrite diversity. Front Mol Neurosci 2022; 15:926567. [PMID: 36452406 PMCID: PMC9702092 DOI: 10.3389/fnmol.2022.926567] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 10/27/2022] [Indexed: 11/15/2022] Open
Abstract
Uncovering molecular mechanisms regulating dendritic diversification is essential to understanding the formation and modulation of functional neural circuitry. Transcription factors play critical roles in promoting dendritic diversity and here, we identify PP2A phosphatase function as a downstream effector of Cut-mediated transcriptional regulation of dendrite development. Mutant analyses of the PP2A catalytic subunit (mts) or the scaffolding subunit (PP2A-29B) reveal cell-type specific regulatory effects with the PP2A complex required to promote dendritic growth and branching in Drosophila Class IV (CIV) multidendritic (md) neurons, whereas in Class I (CI) md neurons, PP2A functions in restricting dendritic arborization. Cytoskeletal analyses reveal requirements for Mts in regulating microtubule stability/polarity and F-actin organization/dynamics. In CIV neurons, mts knockdown leads to reductions in dendritic localization of organelles including mitochondria and satellite Golgi outposts, while CI neurons show increased Golgi outpost trafficking along the dendritic arbor. Further, mts mutant neurons exhibit defects in neuronal polarity/compartmentalization. Finally, genetic interaction analyses suggest β-tubulin subunit 85D is a common PP2A target in CI and CIV neurons, while FoxO is a putative target in CI neurons.
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Affiliation(s)
| | - Erin N. Lottes
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Sumit Nanda
- Center for Neural Informatics, Structures, and Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, United States
| | - Andre Golshir
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Atit A. Patel
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, and Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, United States
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
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8
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Lin CH, Chen YC, Chan SP, Ou CY. TIAM-1 differentially regulates dendritic and axonal microtubule organization in patterning neuronal development through its multiple domains. PLoS Genet 2022; 18:e1010454. [PMID: 36223408 PMCID: PMC9612824 DOI: 10.1371/journal.pgen.1010454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 10/27/2022] [Accepted: 09/29/2022] [Indexed: 12/02/2022] Open
Abstract
Axon and dendrite development require the cooperation of actin and microtubule cytoskeletons. Microtubules form a well-organized network to direct polarized trafficking and support neuronal processes formation with distinct actin structures. However, it is largely unknown how cytoskeleton regulators differentially regulate microtubule organization in axon and dendrite development. Here, we characterize the role of actin regulators in axon and dendrite development and show that the RacGEF TIAM-1 regulates dendritic patterns through its N-terminal domains and suppresses axon growth through its C-terminal domains. TIAM-1 maintains plus-end-out microtubule orientation in posterior dendrites and prevents the accumulation of microtubules in the axon. In somatodendritic regions, TIAM-1 interacts with UNC-119 and stabilizes the organization between actin filaments and microtubules. UNC-119 is required for TIAM-1 to control axon growth, and its expression levels determine axon length. Taken together, TIAM-1 regulates neuronal microtubule organization and patterns axon and dendrite development respectively through its different domains.
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Affiliation(s)
- Chih-Hsien Lin
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ying-Chun Chen
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shih-Peng Chan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chan-Yen Ou
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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9
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Antagonistic Activities of Fmn2 and ADF Regulate Axonal F-Actin Patch Dynamics and the Initiation of Collateral Branching. J Neurosci 2022; 42:7355-7369. [PMID: 36481742 PMCID: PMC9525169 DOI: 10.1523/jneurosci.3107-20.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 08/17/2022] [Accepted: 08/22/2022] [Indexed: 12/15/2022] Open
Abstract
Interstitial collateral branching of axons is a critical component in the development of functional neural circuits. Axon collateral branches are established through a series of cellular processes initiated by the development of a specialized, focal F-actin network in axons. The formation, maintenance and remodeling of this F-actin patch is critical for the initiation of axonal protrusions that are subsequently consolidated to form a collateral branch. However, the mechanisms regulating F-actin patch dynamics are poorly understood. Fmn2 is a formin family member implicated in multiple neurodevelopmental disorders. We find that Fmn2 regulates the initiation of axon collateral protrusions in chick spinal neurons and in zebrafish motor neurons. Fmn2 localizes to the protrusion-initiating axonal F-actin patches and regulates the lifetime and size of these F-actin networks. The F-actin nucleation activity of Fmn2 is necessary for F-actin patch stability but not for initiating patch formation. We show that Fmn2 insulates the F-actin patches from disassembly by the actin-depolymerizing factor, ADF, and promotes long-lived, larger patches that are competent to initiate axonal protrusions. The regulation of axonal branching can contribute to the neurodevelopmental pathologies associated with Fmn2 and the dynamic antagonism between Fmn2 and ADF may represent a general mechanism of formin-dependent protection of Arp2/3-initiated F-actin networks from disassembly.SIGNIFICANCE STATEMENT Axonal branching is a key process in the development of functional circuits and neural plasticity. Axon collateral branching is initiated by the elaboration of F-actin filaments from discrete axonal F-actin networks. We show that the neurodevelopmental disorder-associated formin, Fmn2, is a critical regulator of axon collateral branching. Fmn2 localizes to the collateral branch-inducing F-actin patches in axons and regulates the stability of these actin networks. The F-actin nucleation activity of Fmn2 protects the patches from ADF-mediated disassembly. Opposing activities of Fmn2 and ADF exert a dynamic regulatory control on axon collateral branch initiation and may underly the neurodevelopmental defects associated with Fmn2.
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10
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Li H, Sung HH, Huang YC, Cheng YJ, Yeh HF, Pi H, Giniger E, Chien CT. Fringe-positive Golgi outposts unite temporal Furin 2 convertase activity and spatial Delta signal to promote dendritic branch retraction. Cell Rep 2022; 40:111372. [PMID: 36130510 DOI: 10.1016/j.celrep.2022.111372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 07/07/2022] [Accepted: 08/25/2022] [Indexed: 11/19/2022] Open
Abstract
Golgi outposts (GOPs) in dendrites are known for their role in promoting branch extension, but whether GOPs have other functions is unclear. We found that terminal branches of Drosophila class IV dendritic arborization (C4da) neurons actively grow during the early third-instar (E3) larval stage but retract in the late third (L3) stage. Interestingly, the Fringe (Fng) glycosyltransferase localizes increasingly at GOPs in distal dendritic regions through the E3 to the L3 stage. Expression of the endopeptidase Furin 2 (Fur2), which proteolyzes and inactivates Fng, decreases from E3 to L3 in C4da neurons, thereby increasing Fng-positive GOPs in dendrites. The epidermal Delta ligand and neuronal Notch receptor, the substrate for Fng-mediated O-glycosylation, also negatively regulate dendrite growth. Fng inhibits actin dynamics in dendrites, linking dendritic branch retraction to suppression of the C4da-mediated thermal nociception response in late larval stages. Thus, Fng-positive GOPs function in dendrite retraction, which would add another function to the repertoire of GOPs in dendrite arborization.
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Affiliation(s)
- Hsun Li
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan; Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang Ming Chiao Tung University and Academia Sinica, Taipei 11529, Taiwan
| | - Hsin-Ho Sung
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Chun Huang
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hsiao-Fong Yeh
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan 33302, Taiwan
| | - Haiwei Pi
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan 33302, Taiwan
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan; Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang Ming Chiao Tung University and Academia Sinica, Taipei 11529, Taiwan; Neuroscience Program of Academia Sinica, Academia Sinica, Taipei 11529, Taiwan.
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11
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Li H, Gavis ER. The Drosophila fragile X mental retardation protein modulates the neuronal cytoskeleton to limit dendritic arborization. Development 2022; 149:275257. [DOI: 10.1242/dev.200379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 04/21/2022] [Indexed: 01/02/2023]
Abstract
ABSTRACT
Dendritic arbor development is a complex, highly regulated process. Post-transcriptional regulation mediated by RNA-binding proteins plays an important role in neuronal dendrite morphogenesis by delivering on-site, on-demand protein synthesis. Here, we show how the Drosophila fragile X mental retardation protein (FMRP), a conserved RNA-binding protein, limits dendrite branching to ensure proper neuronal function during larval sensory neuron development. FMRP knockdown causes increased dendritic terminal branch growth and a resulting overelaboration defect due, in part, to altered microtubule stability and dynamics. FMRP also controls dendrite outgrowth by regulating the Drosophila profilin homolog chickadee (chic). FMRP colocalizes with chic mRNA in dendritic granules and regulates its dendritic localization and protein expression. Whereas RNA-binding domains KH1 and KH2 are both crucial for FMRP-mediated dendritic regulation, KH2 specifically is required for FMRP granule formation and chic mRNA association, suggesting a link between dendritic FMRP granules and FMRP function in dendrite elaboration. Our studies implicate FMRP-mediated modulation of both the neuronal microtubule and actin cytoskeletons in multidendritic neuronal architecture, and provide molecular insight into FMRP granule formation and its relevance to FMRP function in dendritic patterning.
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Affiliation(s)
- Hui Li
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Elizabeth R. Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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12
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The branching code: A model of actin-driven dendrite arborization. Cell Rep 2022; 39:110746. [PMID: 35476974 DOI: 10.1016/j.celrep.2022.110746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/24/2021] [Accepted: 04/06/2022] [Indexed: 11/21/2022] Open
Abstract
The cytoskeleton is crucial for defining neuronal-type-specific dendrite morphologies. To explore how the complex interplay of actin-modulatory proteins (AMPs) can define neuronal types in vivo, we focused on the class III dendritic arborization (c3da) neuron of Drosophila larvae. Using computational modeling, we reveal that the main branches (MBs) of c3da neurons follow general models based on optimal wiring principles, while the actin-enriched short terminal branches (STBs) require an additional growth program. To clarify the cellular mechanisms that define this second step, we thus concentrated on STBs for an in-depth quantitative description of dendrite morphology and dynamics. Applying these methods systematically to mutants of six known and novel AMPs, we revealed the complementary roles of these individual AMPs in defining STB properties. Our data suggest that diverse dendrite arbors result from a combination of optimal-wiring-related growth and individualized growth programs that are neuron-type specific.
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13
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Zanganeh S, Goodarzi N, Doroudian M, Movahed E. Potential COVID-19 therapeutic approaches targeting angiotensin-converting enzyme 2; An updated review. Rev Med Virol 2021; 32:e2321. [PMID: 34958163 DOI: 10.1002/rmv.2321] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/24/2021] [Accepted: 11/30/2021] [Indexed: 12/14/2022]
Abstract
COVID-19 has spread swiftly throughout the world posing a global health emergency. The significant numbers of deaths attributed to this pandemic have researchers battling to understand this new, dangerous virus. Researchers are looking to find possible treatment regimens and develop effective therapies. This study aims to provide an overview of published scientific information on potential treatments, emphasizing angiotensin-converting enzyme II (ACE2) inhibitors as one of the most important drug targets. SARS-CoV-2 receptor-binding domain (RBD); as a viral attachment or entry inhibitor against SARS-CoV-2, human recombinant soluble ACE2; as a genetically modified soluble form of ACE2 to compete with membrane-bound ACE2, and microRNAs (miRNAs); as a negative regulator of the expression of ACE2/TMPRSS2 to inhibit SARS-CoV2 entry into cells, are the potential therapeutic approaches discussed thoroughly in this article. This review provides the groundwork for the ongoing development of therapeutic agents and effective treatments against SARS-COV-2.
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Affiliation(s)
- Saba Zanganeh
- Department of Cell and Molecular Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran
| | - Nima Goodarzi
- Department of Cell and Molecular Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran
| | - Mohammad Doroudian
- Department of Cell and Molecular Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran
| | - Elaheh Movahed
- Wadsworth Center, New York State Department of Health, Albany, New Year, USA
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14
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Hogg PW, Coleman P, Dellazizzo Toth T, Haas K. Quantifying neuronal structural changes over time using dynamic morphometrics. Trends Neurosci 2021; 45:106-119. [PMID: 34815102 DOI: 10.1016/j.tins.2021.10.011] [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: 06/07/2021] [Revised: 10/12/2021] [Accepted: 10/25/2021] [Indexed: 11/29/2022]
Abstract
Brain circuit development involves tremendous structural formation and rearrangement of dendrites, axons, and the synaptic connections between them. Direct studies of neuronal morphogenesis are now possible through recent developments in multiple technologies, including single-neuron labeling, time-lapse imaging in intact tissues, and 4D rendering software capable of tracking neural growth over periods spanning minutes to days. These methods allow detailed quantification of structural changes of neurons over time, called dynamic morphometrics, providing new insights into fundamental growth patterns, underlying molecular mechanisms, and the intertwined influences of external factors, including neural activity, and intrinsic genetic programs. Here, we review the methods of dynamic morphometrics sampling and analyses, focusing on their applications to studies of activity-driven dendritogenesis in vertebrate systems.
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Affiliation(s)
- Peter William Hogg
- Department of Cellular and Physiological Sciences, Centre for Brain Health, School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
| | - Patrick Coleman
- Department of Cellular and Physiological Sciences, Centre for Brain Health, School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
| | - Tristan Dellazizzo Toth
- Department of Cellular and Physiological Sciences, Centre for Brain Health, School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
| | - Kurt Haas
- Department of Cellular and Physiological Sciences, Centre for Brain Health, School of Biomedical Engineering, University of British Columbia, Vancouver, Canada.
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15
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Kilo L, Stürner T, Tavosanis G, Ziegler AB. Drosophila Dendritic Arborisation Neurons: Fantastic Actin Dynamics and Where to Find Them. Cells 2021; 10:2777. [PMID: 34685757 PMCID: PMC8534399 DOI: 10.3390/cells10102777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 01/27/2023] Open
Abstract
Neuronal dendrites receive, integrate, and process numerous inputs and therefore serve as the neuron's "antennae". Dendrites display extreme morphological diversity across different neuronal classes to match the neuron's specific functional requirements. Understanding how this structural diversity is specified is therefore important for shedding light on information processing in the healthy and diseased nervous system. Popular models for in vivo studies of dendrite differentiation are the four classes of dendritic arborization (c1da-c4da) neurons of Drosophila larvae with their class-specific dendritic morphologies. Using da neurons, a combination of live-cell imaging and computational approaches have delivered information on the distinct phases and the time course of dendrite development from embryonic stages to the fully developed dendritic tree. With these data, we can start approaching the basic logic behind differential dendrite development. A major role in the definition of neuron-type specific morphologies is played by dynamic actin-rich processes and the regulation of their properties. This review presents the differences in the growth programs leading to morphologically different dendritic trees, with a focus on the key role of actin modulatory proteins. In addition, we summarize requirements and technological progress towards the visualization and manipulation of such actin regulators in vivo.
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Affiliation(s)
- Lukas Kilo
- Dendrite Differentiation, German Center for Neurodegenerative Diseases, 53115 Bonn, Germany; (L.K.); (G.T.)
| | - Tomke Stürner
- Department of Zoology, University of Cambridge, Cambridge CB2 1TN, UK;
| | - Gaia Tavosanis
- Dendrite Differentiation, German Center for Neurodegenerative Diseases, 53115 Bonn, Germany; (L.K.); (G.T.)
- LIMES-Institute, University of Bonn, 53115 Bonn, Germany
| | - Anna B. Ziegler
- Institute of Neuro- and Behavioral Biology, University of Münster, 48149 Münster, Germany
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16
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Chen J, Cao J. Astrocyte-to-neuron transportation of enhanced green fluorescent protein in cerebral cortex requires F-actin dependent tunneling nanotubes. Sci Rep 2021; 11:16798. [PMID: 34408233 PMCID: PMC8373867 DOI: 10.1038/s41598-021-96332-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 08/06/2021] [Indexed: 11/25/2022] Open
Abstract
Tunneling nanotube (TNT), a dynamic cell–cell contact, is dependent on actin polymerization. TNTs are efficient in transporting ions, proteins and organelles intercellularly, which are important mechanisms in physiological and pathological processes. Reported studies on the existence and function of TNTs among neural cells focus on cultured cell for the convenience in detecting TNTs’ ultrastructure. In this study, the adeno-associated virus (AAV-GFAP-EGFP-p2A-cre) was injected into the cerebral cortex of knock-in mice ROSA26 GNZ. GFAP promoter initiated the expression of enhanced green fluorescent protein (EGFP) in infected astrocytes. At 10 days post injection (10 DPI), EGFP transferred from astrocytes in layer I–III to neurons in layer V. The dissemination of EGFP was not through endocytosis or exosome. Applying microscopes, we found that the intercellular transportation of EGFP through contact connection was F-actin dependent. Therefore, we concluded that EGFP transported from astrocytes to neurons in cortex via F-actin dependent TNTs. This study first proved that proteins transported intercellularly via TNTs in brain.
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Affiliation(s)
- Jing Chen
- Institute of Life Sciences, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China. .,Key Lab of Organ Development and Regeneration of Zhejiang Province, Hangzhou, Zhejiang, China. .,Key Lab of GEM Resource and Model Research of Hangzhou, Hangzhou, Zhejiang, China.
| | - Junyan Cao
- Institute of Life Sciences, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China.,Key Lab of Organ Development and Regeneration of Zhejiang Province, Hangzhou, Zhejiang, China.,Key Lab of GEM Resource and Model Research of Hangzhou, Hangzhou, Zhejiang, China
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17
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Shi R, Kramer DA, Chen B, Shen K. A two-step actin polymerization mechanism drives dendrite branching. Neural Dev 2021; 16:3. [PMID: 34281597 PMCID: PMC8290545 DOI: 10.1186/s13064-021-00154-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 06/14/2021] [Indexed: 11/10/2022] Open
Abstract
Background Dendrite morphogenesis plays an essential role in establishing the connectivity and receptive fields of neurons during the development of the nervous system. To generate the diverse morphologies of branched dendrites, neurons use external cues and cell surface receptors to coordinate intracellular cytoskeletal organization; however, the molecular mechanisms of how this signaling forms branched dendrites are not fully understood. Methods We performed in vivo time-lapse imaging of the PVD neuron in C. elegans in several mutants of actin regulatory proteins, such as the WAVE Regulatory Complex (WRC) and UNC-34 (homolog of Enabled/Vasodilator-stimulated phosphoprotein (Ena/VASP)). We examined the direct interaction between the WRC and UNC-34 and analyzed the localization of UNC-34 in vivo using transgenic worms expressing UNC-34 fused to GFP. Results We identify a stereotyped sequence of morphological events during dendrite outgrowth in the PVD neuron in C. elegans. Specifically, local increases in width (“swellings”) give rise to filopodia to facilitate a “rapid growth and pause” mode of growth. In unc-34 mutants, filopodia fail to form but swellings are intact. In WRC mutants, dendrite growth is largely absent, resulting from a lack of both swelling and filopodia formation. We also found that UNC-34 can directly bind to the WRC. Disrupting this binding by deleting the UNC-34 EVH1 domain prevented UNC-34 from localizing to swellings and dendrite tips, resulting in a stunted dendritic arbor and reduced filopodia outgrowth. Conclusions We propose that regulators of branched and linear F-actin cooperate to establish dendritic branches. By combining our work with existing literature, we propose that the dendrite guidance receptor DMA-1 recruits the WRC, which polymerizes branched F-actin to generate “swellings” on a mother dendrite. Then, WRC recruits the actin elongation factor UNC-34/Ena/VASP to initiate growth of a new dendritic branch from the swelling, with the help of the actin-binding protein UNC-115/abLIM. Extension of existing dendrites also proceeds via swelling formation at the dendrite tip followed by UNC-34-mediated outgrowth. Following dendrite initiation and extension, the stabilization of branches by guidance receptors further recruits WRC, resulting in an iterative process to build a complex dendritic arbor. Supplementary Information The online version contains supplementary material available at 10.1186/s13064-021-00154-0.
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Affiliation(s)
- Rebecca Shi
- Department of Biology, Stanford University, Stanford, CA, 94305, USA.,Neurosciences IDP, Stanford University, Stanford, CA, 94305, USA
| | - Daniel A Kramer
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Baoyu Chen
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Kang Shen
- Department of Biology, Stanford University, Stanford, CA, 94305, USA. .,Howard Hughes Medical Institute, Stanford University, Stanford, CA, 94305, USA.
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18
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Liao M, Liang X, Howard J. The narrowing of dendrite branches across nodes follows a well-defined scaling law. Proc Natl Acad Sci U S A 2021; 118:e2022395118. [PMID: 34215693 PMCID: PMC8271565 DOI: 10.1073/pnas.2022395118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The systematic variation of diameters in branched networks has tantalized biologists since the discovery of da Vinci's rule for trees. Da Vinci's rule can be formulated as a power law with exponent two: The square of the mother branch's diameter is equal to the sum of the squares of those of the daughters. Power laws, with different exponents, have been proposed for branching in circulatory systems (Murray's law with exponent 3) and in neurons (Rall's law with exponent 3/2). The laws have been derived theoretically, based on optimality arguments, but, for the most part, have not been tested rigorously. Using superresolution methods to measure the diameters of dendrites in highly branched Drosophila class IV sensory neurons, we have found that these types of power laws do not hold. In their place, we have discovered a different diameter-scaling law: The cross-sectional area is proportional to the number of dendrite tips supported by the branch plus a constant, corresponding to a minimum diameter of the terminal dendrites. The area proportionality accords with a requirement for microtubules to transport materials and nutrients for dendrite tip growth. The minimum diameter may be set by the force, on the order of a few piconewtons, required to bend membrane into the highly curved surfaces of terminal dendrites. Because the observed scaling differs from Rall's law, we propose that cell biological constraints, such as intracellular transport and protrusive forces generated by the cytoskeleton, are important in determining the branched morphology of these cells.
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Affiliation(s)
- Maijia Liao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520;
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19
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Aihara S, Fujimoto S, Sakaguchi R, Imai T. BMPR-2 gates activity-dependent stabilization of primary dendrites during mitral cell remodeling. Cell Rep 2021; 35:109276. [PMID: 34161760 DOI: 10.1016/j.celrep.2021.109276] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 04/28/2021] [Accepted: 05/28/2021] [Indexed: 11/29/2022] Open
Abstract
Developing neurons initially form excessive neurites and then remodel them based on molecular cues and neuronal activity. Developing mitral cells in the olfactory bulb initially extend multiple primary dendrites. They then stabilize single primary dendrites while eliminating others. However, the mechanisms underlying selective dendrite remodeling remain elusive. Using CRISPR-Cas9-based knockout screening combined with in utero electroporation, we identify BMPR-2 as a key regulator for selective dendrite stabilization. Bmpr2 knockout and its rescue experiments show that BMPR-2 inhibits LIMK without ligands and thereby permits dendrite destabilization. In contrast, the overexpression of antagonists and agonists indicates that ligand-bound BMPR-2 stabilizes dendrites, most likely by releasing LIMK. Using genetic and FRET imaging experiments, we demonstrate that free LIMK is activated by NMDARs via Rac1, facilitating dendrite stabilization through F-actin formation. Thus, the selective stabilization of primary dendrites is ensured by concomitant inputs of BMP ligands and neuronal activity.
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Affiliation(s)
- Shuhei Aihara
- Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Laboratory for Sensory Circuit Formation, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Satoshi Fujimoto
- Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Laboratory for Sensory Circuit Formation, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Richi Sakaguchi
- Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Laboratory for Sensory Circuit Formation, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Takeshi Imai
- Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Laboratory for Sensory Circuit Formation, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
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20
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Tavosanis G. Dendrite enlightenment. Curr Opin Neurobiol 2021; 69:222-230. [PMID: 34134010 DOI: 10.1016/j.conb.2021.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 12/18/2022]
Abstract
Neuronal dendrites acquire complex morphologies during development. These are not just the product of cell-intrinsic developmental programs; rather they are defined in close interaction with the cellular environment. Thus, to understand the molecular cascades that yield appropriate morphologies, it is essential to investigate them in vivo, in the actual complex tissue environment encountered by the differentiating neuron in the developing animal. Particularly, genetic approaches have pointed to factors controlling dendrite differentiation in vivo. These suggest that localized and transient molecular cascades might underlie the formation and stabilization of dendrite branches with neuron type-specific characteristics. Here, I highlight the need for studies of neuronal dendrite differentiation in the animal, the challenges provided by such an approach, and the promising pathways that have recently opened.
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Affiliation(s)
- Gaia Tavosanis
- German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1/99, Bonn, 53127, Germany; LIMES Institute, University of Bonn, Carl-Troll-Str. 3, Bonn, 53115, Germany.
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21
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Ricolo D, Castro-Ribera J, Araújo SJ. Cytoskeletal players in single-cell branching morphogenesis. Dev Biol 2021; 477:22-34. [PMID: 34004181 DOI: 10.1016/j.ydbio.2021.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/25/2021] [Accepted: 05/04/2021] [Indexed: 12/22/2022]
Abstract
Branching networks are a very common feature of multicellular animals and underlie the formation and function of numerous organs including the nervous system, the respiratory system, the vasculature and many internal glands. These networks range from subcellular structures such as dendritic trees to large multicellular tissues such as the lungs. The production of branched structures by single cells, so called subcellular branching, which has been better described in neurons and in cells of the respiratory and vascular systems, involves complex cytoskeletal remodelling events. In Drosophila, tracheal system terminal cells (TCs) and nervous system dendritic arborisation (da) neurons are good model systems for these subcellular branching processes. During development, the generation of subcellular branches by single-cells is characterized by extensive remodelling of the microtubule (MT) network and actin cytoskeleton, followed by vesicular transport and membrane dynamics. In this review, we describe the current knowledge on cytoskeletal regulation of subcellular branching, based on the terminal cells of the Drosophila tracheal system, but drawing parallels with dendritic branching and vertebrate vascular subcellular branching.
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Affiliation(s)
- Delia Ricolo
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028, Barcelona, Spain; Institute of Biomedicine University of Barcelona (IBUB), Barcelona, Spain
| | - Judith Castro-Ribera
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028, Barcelona, Spain; Institute of Biomedicine University of Barcelona (IBUB), Barcelona, Spain
| | - Sofia J Araújo
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028, Barcelona, Spain; Institute of Biomedicine University of Barcelona (IBUB), Barcelona, Spain.
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22
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Lin TY, Chen PJ, Yu HH, Hsu CP, Lee CH. Extrinsic Factors Regulating Dendritic Patterning. Front Cell Neurosci 2021; 14:622808. [PMID: 33519386 PMCID: PMC7838386 DOI: 10.3389/fncel.2020.622808] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/17/2020] [Indexed: 12/18/2022] Open
Abstract
Stereotypic dendrite arborizations are key morphological features of neuronal identity, as the size, shape and location of dendritic trees determine the synaptic input fields and how information is integrated within developed neural circuits. In this review, we focus on the actions of extrinsic intercellular communication factors and their effects on intrinsic developmental processes that lead to dendrite patterning. Surrounding neurons or supporting cells express adhesion receptors and secreted proteins that respectively, act via direct contact or over short distances to shape, size, and localize dendrites during specific developmental stages. The different ligand-receptor interactions and downstream signaling events appear to direct dendrite morphogenesis by converging on two categorical mechanisms: local cytoskeletal and adhesion modulation and global transcriptional regulation of key dendritic growth components, such as lipid synthesis enzymes. Recent work has begun to uncover how the coordinated signaling of multiple extrinsic factors promotes complexity in dendritic trees and ensures robust dendritic patterning.
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Affiliation(s)
- Tzu-Yang Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Pei-Ju Chen
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Hung-Hsiang Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Chao-Ping Hsu
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chi-Hon Lee
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
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23
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Alizzi RA, Xu D, Tenenbaum CM, Wang W, Gavis ER. The ELAV/Hu protein Found in neurons regulates cytoskeletal and ECM adhesion inputs for space-filling dendrite growth. PLoS Genet 2020; 16:e1009235. [PMID: 33370772 PMCID: PMC7793258 DOI: 10.1371/journal.pgen.1009235] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 01/08/2021] [Accepted: 10/29/2020] [Indexed: 12/17/2022] Open
Abstract
Dendritic arbor morphology influences how neurons receive and integrate extracellular signals. We show that the ELAV/Hu family RNA-binding protein Found in neurons (Fne) is required for space-filling dendrite growth to generate highly branched arbors of Drosophila larval class IV dendritic arborization neurons. Dendrites of fne mutant neurons are shorter and more dynamic than in wild-type, leading to decreased arbor coverage. These defects result from both a decrease in stable microtubules and loss of dendrite-substrate interactions within the arbor. Identification of transcripts encoding cytoskeletal regulators and cell-cell and cell-ECM interacting proteins as Fne targets using TRIBE further supports these results. Analysis of one target, encoding the cell adhesion protein Basigin, indicates that the cytoskeletal defects contributing to branch instability in fne mutant neurons are due in part to decreased Basigin expression. The ability of Fne to coordinately regulate the cytoskeleton and dendrite-substrate interactions in neurons may shed light on the behavior of cancer cells ectopically expressing ELAV/Hu proteins. Different types of neurons have different sizes and shapes that are tailored to their particular functions. In the fruit fly larva, a set of sensory neurons called class IV da neurons have highly branched trees of dendrites that cover the epidermis to sense potentially harmful stimuli. Neurons whose dendrites completely fill the territory they sample are also found in zebrafish, worms, mice and humans. We show that an RNA-binding protein called Fne plays an important role in coordinating different contributions to dendrite branching in class IV da neurons by impacting the organization of the cytoskeleton within the neuron and the ability of the dendrite to contact the substratum outside of it. The identification of mRNAs that code for cytoskeleton regulators and adhesive proteins as targets of Fne using a genome-wide approach further supports these results. While the ability of Fne to exert control over such proteins is crucial to generating the space-filling growth of neurons, it can be deleterious if not properly employed, such as when the homologs of Fne are expressed in cancer cells.
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Affiliation(s)
- Rebecca A. Alizzi
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Derek Xu
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Conrad M. Tenenbaum
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Wei Wang
- Lewis-Sigler Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Elizabeth R. Gavis
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
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24
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Wolterhoff N, Gigengack U, Rumpf S. PP2A phosphatase is required for dendrite pruning via actin regulation in Drosophila. EMBO Rep 2020; 21:e48870. [PMID: 32207238 PMCID: PMC7202059 DOI: 10.15252/embr.201948870] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 02/27/2020] [Accepted: 03/04/2020] [Indexed: 12/22/2022] Open
Abstract
Large‐scale pruning, the developmentally regulated degeneration of axons or dendrites, is an important specificity mechanism during neuronal circuit formation. The peripheral sensory class IV dendritic arborization (c4da) neurons of Drosophila larvae specifically prune their dendrites at the onset of metamorphosis in an ecdysone‐dependent manner. Dendrite pruning requires local cytoskeleton remodeling, and the actin‐severing enzyme Mical is an important ecdysone target. In a screen for pruning factors, we identified the protein phosphatase 2 A (PP2A). PP2A interacts genetically with the actin‐severing enzymes Mical and cofilin as well as other actin regulators during pruning. Moreover, Drosophila cofilin undergoes a change in localization at the onset of metamorphosis indicative of a change in actin dynamics. This change is abolished both upon loss of Mical and PP2A. We conclude that PP2A regulates actin dynamics during dendrite pruning.
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Affiliation(s)
- Neele Wolterhoff
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Ulrike Gigengack
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Sebastian Rumpf
- Institute for Neurobiology, University of Münster, Münster, Germany
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25
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Yang WK, Chien CT. Beyond being innervated: the epidermis actively shapes sensory dendritic patterning. Open Biol 2020; 9:180257. [PMID: 30914004 PMCID: PMC6451362 DOI: 10.1098/rsob.180257] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sensing environmental cues requires well-built neuronal circuits linked to the body surface. Sensory neurons generate dendrites to innervate surface epithelium, thereby making it the largest sensory organ in the body. Previous studies have illustrated that neuronal type, physiological function and branching patterns are determined by intrinsic factors. Perhaps for effective sensation or protection, sensory dendrites bind to or are surrounded by the substrate epidermis. Recent studies have shed light on the mechanisms by which dendrites interact with their substrates. These interactions suggest that substrates can regulate dendrite guidance, arborization and degeneration. In this review, we focus on recent studies of Drosophila and Caenorhabditis elegans that demonstrate how epidermal cells can regulate dendrites in several aspects.
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Affiliation(s)
- Wei-Kang Yang
- Institute of Molecular Biology, Academia Sinica , Taipei 115 , Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica , Taipei 115 , Taiwan
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26
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Lai WF, Wong WT. Roles of the actin cytoskeleton in aging and age-associated diseases. Ageing Res Rev 2020; 58:101021. [PMID: 31968269 DOI: 10.1016/j.arr.2020.101021] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 01/06/2020] [Accepted: 01/17/2020] [Indexed: 12/12/2022]
Abstract
The integrity of the cytoskeleton is essential to diverse cellular processes such as phagocytosis and intracellular trafficking. Disruption of the organization and dynamics of the actin cytoskeleton leads to age-associated symptoms and diseases, ranging from cancer to neurodegeneration. In addition, changes in the integrity of the actin cytoskeleton disrupt the functioning of not only somatic and stem cells but also gametes, resulting in aberrant embryonic development. Strategies to preserve the integrity and dynamics of the cytoskeleton are, therefore, potentially therapeutic to age-related disorders. The objective of this article is to revisit the current understanding of the roles played by the actin cytoskeleton in aging, and to review the opportunities and challenges for the transition of basic research into intervention development. It is hoped that, with the snapshot of evidence regarding changes in actin dynamics with advanced age, insights into future research directions can be attained.
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Affiliation(s)
- Wing-Fu Lai
- School of Pharmaceutical Sciences, Shenzhen University, PR China; School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, PR China; Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong Special Administrative Region, PR China.
| | - Wing-Tak Wong
- Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong Special Administrative Region, PR China
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27
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Chakrabarty N, Jung P. Stochastic models of polymerization-based axonal actin transport. Phys Biol 2019; 16:056001. [PMID: 31195374 DOI: 10.1088/1478-3975/ab29cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent advances in live cell imaging of F-actin structures, combined with pulse-chase imaging and computational modeling have suggested that actin is transported along the axon via biased polymerization of metastable actin fibers (actin trails). This mechanism is distinct from motor driven polymer transport, such as for neurofilaments and can be best described as molecular hitchhiking, where G-actin molecules are intermittently incorporated into actin fibers which grow preferentially in the anterograde direction. In this paper, we discuss how various axonal and actin trail parameters like axon diameter, trail nucleation rates, basal G-actin concentration, and trail length influence the transport rate. These predictions can help guide future experiments to verify this novel protein transport mechanism. We introduce a simplified, analytically solvable model of actin transport which relates these parameters to experimentally measurable quantities. We also discuss why a simple diffusion-based transport mechanism cannot explain bulk actin transport in the axon.
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Affiliation(s)
- Nilaj Chakrabarty
- Department of Physics and Astronomy, Neuroscience Program and Quantitative Biology Institute, Athens, OH 45701, United States of America
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28
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Sundararajan L, Smith CJ, Watson JD, Millis BA, Tyska MJ, Miller DM. Actin assembly and non-muscle myosin activity drive dendrite retraction in an UNC-6/Netrin dependent self-avoidance response. PLoS Genet 2019; 15:e1008228. [PMID: 31220078 PMCID: PMC6605669 DOI: 10.1371/journal.pgen.1008228] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/02/2019] [Accepted: 06/04/2019] [Indexed: 01/08/2023] Open
Abstract
Dendrite growth is constrained by a self-avoidance response that induces retraction but the downstream pathways that balance these opposing mechanisms are unknown. We have proposed that the diffusible cue UNC-6(Netrin) is captured by UNC-40(DCC) for a short-range interaction with UNC-5 to trigger self-avoidance in the C. elegans PVD neuron. Here we report that the actin-polymerizing proteins UNC-34(Ena/VASP), WSP-1(WASP), UNC-73(Trio), MIG-10(Lamellipodin) and the Arp2/3 complex effect dendrite retraction in the self-avoidance response mediated by UNC-6(Netrin). The paradoxical idea that actin polymerization results in shorter rather than longer dendrites is explained by our finding that NMY-1 (non-muscle myosin II) is necessary for retraction and could therefore mediate this effect in a contractile mechanism. Our results also show that dendrite length is determined by the antagonistic effects on the actin cytoskeleton of separate sets of effectors for retraction mediated by UNC-6(Netrin) versus outgrowth promoted by the DMA-1 receptor. Thus, our findings suggest that the dendrite length depends on an intrinsic mechanism that balances distinct modes of actin assembly for growth versus retraction. Neurons may extend highly branched dendrites to detect input over a broad receptive field. The formation of actin filaments may drive dendrite elongation. The architecture of the dendritic arbor also depends on mechanisms that limit expansion. For example, sister dendrites from a single neuron usually do not overlap due to self-avoidance. Although cell surface proteins are known to mediate self-avoidance, the downstream pathways that drive dendrite retraction in this phenomenon are largely unknown. Studies of the highly branched PVD sensory neuron in C. elegans have suggested a model of self-avoidance in which the UNC-40/DCC receptor captures the diffusible cue UNC-6/Netrin at the tips of PVD dendrites where it interacts with the UNC-5 receptor on an opposing sister dendrite to induce retraction. Here we report genetic evidence that UNC-5-dependent retraction requires downstream actin polymerization. This finding evokes a paradox: How might actin polymerization drive both dendrite growth and retraction? We propose two answers: (1) Distinct sets of effectors are involved in actin assembly for growth vs retraction; (2) Non-muscle myosin interacts with a nascent actin assemblage to trigger retraction. Our results show that dendrite length depends on the balanced effects of specific molecular components that induce growth vs retraction.
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Affiliation(s)
- Lakshmi Sundararajan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Cody J. Smith
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Joseph D. Watson
- Neuroscience Graduate Program, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
| | - Bryan A. Millis
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Cell Imaging Shared Resource, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
- Vanderbilt Biophotonics Center, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
| | - Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - David M. Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Neuroscience Graduate Program, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
- * E-mail:
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29
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Yang WK, Chueh YR, Cheng YJ, Siegenthaler D, Pielage J, Chien CT. Epidermis-Derived L1CAM Homolog Neuroglian Mediates Dendrite Enclosure and Blocks Heteroneuronal Dendrite Bundling. Curr Biol 2019; 29:1445-1459.e3. [PMID: 31006568 DOI: 10.1016/j.cub.2019.03.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/31/2019] [Accepted: 03/23/2019] [Indexed: 12/31/2022]
Abstract
Building sensory dendritic arbors requires branching, growth, spacing, and substrate support. The conserved L1CAM family of cell-adhesion molecules generates neuronal isoforms to regulate neurite development in various aspects. However, whether non-neuronal isoforms participate in any of these aspects is unclear. In Drosophila, the L1CAM homolog Neuroglian (Nrg) is expressed as two isoforms: the neuronal isoform Nrg180 on dendritic surfaces of dendritic arborization (da) neurons and the non-neuronal isoform Nrg167 in epidermis innervated by dendrites. We found that epidermal Nrg167 encircles dendrites by interactions with dendritic Nrg180 to support dendrite growth, stabilization, and enclosure inside epidermis. Interestingly, whereas Nrg180 forms homophilic interactions to facilitate axonal bundling, heteroneuronal dendrites in the same innervating field avoid bundling through unknown mechanisms to maintain individual dendritic patterns. Here, we show that both epidermal Nrg167 depletion and neuronal Nrg180 overexpression can cause dendrite bundling, with genetic analyses suggesting that Nrg167-Nrg180 interactions antagonize Nrg180-Nrg180 homophilic interaction to prevent dendrite bundling. Furthermore, internalization of Nrg180 also participates in resolving dendrite bundling, as overexpression of endocytosis-defective Nrg180 and compromising endocytosis in neurons both exacerbated dendrite-bundling defects. Together, our study highlights the functional significance of substrate-derived Nrg167 in conferring dendrite stability, positioning, and avoidance.
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Affiliation(s)
- Wei-Kang Yang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ru Chueh
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Dominique Siegenthaler
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jan Pielage
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
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30
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Sundararajan L, Stern J, Miller DM. Mechanisms that regulate morphogenesis of a highly branched neuron in C. elegans. Dev Biol 2019; 451:53-67. [PMID: 31004567 DOI: 10.1016/j.ydbio.2019.04.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 03/09/2019] [Accepted: 04/05/2019] [Indexed: 02/08/2023]
Abstract
The shape of an individual neuron is linked to its function with axons sending signals to other cells and dendrites receiving them. Although much is known of the mechanisms for axonal outgrowth, the striking complexity of dendritic architecture has hindered efforts to uncover pathways that direct dendritic branching. Here we review the results of an experimental strategy that exploits the power of genetic analysis and live cell imaging of the PVD sensory neuron in C. elegans to reveal key molecular drivers of dendrite morphogenesis.
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Affiliation(s)
- Lakshmi Sundararajan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Jamie Stern
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - David M Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA.
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31
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Stürner T, Tatarnikova A, Mueller J, Schaffran B, Cuntz H, Zhang Y, Nemethova M, Bogdan S, Small V, Tavosanis G. Transient localization of the Arp2/3 complex initiates neuronal dendrite branching in vivo. Development 2019; 146:dev.171397. [PMID: 30910826 DOI: 10.1242/dev.171397] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 03/08/2019] [Indexed: 01/02/2023]
Abstract
The formation of neuronal dendrite branches is fundamental for the wiring and function of the nervous system. Indeed, dendrite branching enhances the coverage of the neuron's receptive field and modulates the initial processing of incoming stimuli. Complex dendrite patterns are achieved in vivo through a dynamic process of de novo branch formation, branch extension and retraction. The first step towards branch formation is the generation of a dynamic filopodium-like branchlet. The mechanisms underlying the initiation of dendrite branchlets are therefore crucial to the shaping of dendrites. Through in vivo time-lapse imaging of the subcellular localization of actin during the process of branching of Drosophila larva sensory neurons, combined with genetic analysis and electron tomography, we have identified the Actin-related protein (Arp) 2/3 complex as the major actin nucleator involved in the initiation of dendrite branchlet formation, under the control of the activator WAVE and of the small GTPase Rac1. Transient recruitment of an Arp2/3 component marks the site of branchlet initiation in vivo These data position the activation of Arp2/3 as an early hub for the initiation of branchlet formation.
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Affiliation(s)
- Tomke Stürner
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V./German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Anastasia Tatarnikova
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V./German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany.,MPI for Neurobiology, 82152 Munich- Martinsried, Germany
| | - Jan Mueller
- Institute of Molecular biotechnology (IMBA), 1030 Wien, Austria
| | - Barbara Schaffran
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V./German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Hermann Cuntz
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, 60528 Frankfurt, Germany.,Frankfurt Institute for Advanced Studies, 60438 Frankfurt, Germany
| | - Yun Zhang
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V./German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Maria Nemethova
- Institute of Molecular biotechnology (IMBA), 1030 Wien, Austria
| | - Sven Bogdan
- Institut für Physiologie und Pathophysiologie, Abteilung Molekulare Zellphysiologie, Phillips-Universität Marburg, 35037 Marburg, Germany
| | - Vic Small
- Institute of Molecular biotechnology (IMBA), 1030 Wien, Austria
| | - Gaia Tavosanis
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V./German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
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32
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Functions of Microtubule Disassembly during Neurite Pruning. Trends Cell Biol 2019; 29:291-297. [PMID: 30683460 DOI: 10.1016/j.tcb.2019.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/27/2018] [Accepted: 01/02/2019] [Indexed: 11/23/2022]
Abstract
Large-scale neurite pruning, the developmentally regulated degeneration of axons or dendrites, is an important specificity mechanism during neuronal circuit formation. Pruning is usually restricted to single neurite branches and can occur by local degeneration or retraction. How this spatial regulation is achieved, and what triggers degeneration locally, are still poorly understood. At the cellular level, pruning involves local cytoskeleton disassembly before branch removal. Recent evidence suggests that microtubule disassembly is the local trigger and that the specific local microtubule organization of axons or dendrites determines where and how neurites degenerate. Based on these data, we propose a general model for spatial pruning regulation by microtubules and discuss how microtubule-associated proteins such as Tau could contribute to these regulatory aspects.
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33
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Yoong LF, Pai YJ, Moore AW. Stages and transitions in dendrite arbor differentiation. Neurosci Res 2019; 138:70-78. [DOI: 10.1016/j.neures.2018.09.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 08/10/2018] [Accepted: 08/14/2018] [Indexed: 12/26/2022]
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34
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Abstract
Proper neuronal wiring is central to all bodily functions, sensory perception, cognition, memory, and learning. Establishment of a functional neuronal circuit is a highly regulated and dynamic process involving axonal and dendritic branching and navigation toward appropriate targets and connection partners. This intricate circuitry includes axo-dendritic synapse formation, synaptic connections formed with effector cells, and extensive dendritic arborization that function to receive and transmit mechanical and chemical sensory inputs. Such complexity is primarily achieved by extensive axonal and dendritic branch formation and pruning. Fundamental to neuronal branching are cytoskeletal dynamics and plasma membrane expansion, both of which are regulated via numerous extracellular and intracellular signaling mechanisms and molecules. This review focuses on recent advances in understanding the biology of neuronal branching.
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Affiliation(s)
- Shalini Menon
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Stephanie Gupton
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, Chapel Hill, NC, 27599, USA.,Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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35
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Abstract
Pai and Moore preview work from Nithianandam and Chien describing new actin structures called blobs that prefigure dendrite branching. The mechanisms by which the actin cytoskeleton regulates dendritic branching are not fully understood. Nithianandam and Chien (2018. J. Cell Biol.https://doi.org/10.1083/jcb.201711136) discover actin blobs, new structures that mediate dynamic actin delivery within a growing dendrite arbor and that mark sites of future branch formation.
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Affiliation(s)
- Yun-Jin Pai
- Neurodiversity, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Adrian W Moore
- Neurodiversity, RIKEN Center for Brain Science, Wako, Saitama, Japan
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