1
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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: 0] [Impact Index Per Article: 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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2
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Rajan S, Yoon J, Wu H, Srapyan S, Baskar R, Ahmed G, Yang T, Grintsevich EE, Reisler E, Terman JR. Disassembly of bundled F-actin and cellular remodeling via an interplay of Mical, cofilin, and F-actin crosslinkers. Proc Natl Acad Sci U S A 2023; 120:e2309955120. [PMID: 37725655 PMCID: PMC10523612 DOI: 10.1073/pnas.2309955120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/11/2023] [Indexed: 09/21/2023] Open
Abstract
Cellular form and function are controlled by the assembly and stability of actin cytoskeletal structures-but disassembling/pruning these structures is equally essential for the plasticity and remodeling that underlie behavioral adaptations. Importantly, the mechanisms of actin assembly have been well-defined-including that it is driven by actin's polymerization into filaments (F-actin) and then often bundling by crosslinking proteins into stable higher-order structures. In contrast, it remains less clear how these stable bundled F-actin structures are rapidly disassembled. We now uncover mechanisms that rapidly and extensively disassemble bundled F-actin. Using biochemical, structural, and imaging assays with purified proteins, we show that F-actin bundled with one of the most prominent crosslinkers, fascin, is extensively disassembled by Mical, the F-actin disassembly enzyme. Furthermore, the product of this Mical effect, Mical-oxidized actin, is poorly bundled by fascin, thereby further amplifying Mical's disassembly effects on bundled F-actin. Moreover, another critical F-actin regulator, cofilin, also affects fascin-bundled filaments, but we find herein that it synergizes with Mical to dramatically amplify its disassembly of bundled F-actin compared to the sum of their individual effects. Genetic and high-resolution cellular assays reveal that Mical also counteracts crosslinking proteins/bundled F-actin in vivo to control cellular extension, axon guidance, and Semaphorin/Plexin cell-cell repulsion. Yet, our results also support the idea that fascin-bundling serves to dampen Mical's F-actin disassembly in vitro and in vivo-and that physiologically relevant cellular remodeling requires a fine-tuned interplay between the factors that build bundled F-actin networks and those that disassemble them.
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Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Jimok Yoon
- Department of Neuroscience, The University of Texas of Southwestern Medical Center, Dallas, TX75390
- Department of Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX75390
| | - Heng Wu
- Department of Neuroscience, The University of Texas of Southwestern Medical Center, Dallas, TX75390
- Department of Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX75390
| | - Sargis Srapyan
- Department of Chemistry and Biochemistry, California State University, Long Beach, CA90840
| | - Raju Baskar
- Department of Neuroscience, The University of Texas of Southwestern Medical Center, Dallas, TX75390
- Department of Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX75390
| | - Giasuddin Ahmed
- Department of Neuroscience, The University of Texas of Southwestern Medical Center, Dallas, TX75390
- Department of Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX75390
| | - Taehong Yang
- Department of Neuroscience, The University of Texas of Southwestern Medical Center, Dallas, TX75390
- Department of Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX75390
| | - Elena E. Grintsevich
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- Department of Chemistry and Biochemistry, California State University, Long Beach, CA90840
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- Molecular Biology Institute, University of California, Los Angeles, CA90095
| | - Jonathan R. Terman
- Department of Neuroscience, The University of Texas of Southwestern Medical Center, Dallas, TX75390
- Department of Pharmacology, The University of Texas of Southwestern Medical Center, Dallas, TX75390
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3
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Liu J, Liu J, Li M, Zhou L, Kong W, Zhang H, Jin P, Lu F, Lin G, Shi L. Division of developmental phases of freshwater leech Whitmania pigra and key genes related to neurogenesis revealed by whole genome and transcriptome analysis. BMC Genomics 2023; 24:203. [PMID: 37069497 PMCID: PMC10111769 DOI: 10.1186/s12864-023-09286-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 03/30/2023] [Indexed: 04/19/2023] Open
Abstract
The freshwater leech Whitmania pigra (W. pigra) Whitman (Annelida phylum) is a model organism for neurodevelopmental studies. However, molecular biology research on its embryonic development is still scarce. Here, we described a series of developmental stages of the W. pigra embryos and defined five broad stages of embryogenesis: cleavage stages, blastocyst stage, gastrula stage, organogenesis and refinement, juvenile. We obtained a total of 239.64 Gb transcriptome data of eight representative developmental phases of embryos (from blastocyst stage to maturity), which was then assembled into 21,482 unigenes according to our reference genome sequenced by single-molecule real-time (SMRT) long-read sequencing. We found 3114 genes differentially expressed during the eight phases with phase-specific expression pattern. Using a comprehensive transcriptome dataset, we demonstrated that 57, 49 and 77 DEGs were respectively related to morphogenesis, signal pathways and neurogenesis. 49 DEGs related to signal pathways included 30 wnt genes, 14 notch genes, and 5 hedgehog genes. In particular, we found a cluster consisting of 7 genes related to signal pathways as well as synapses, which were essential for regulating embryonic development. Eight genes cooperatively participated in regulating neurogenesis. Our results reveal the whole picture of W. pigra development mechanism from the perspective of transcriptome and provide new clues for organogenesis and neurodevelopmental studies of Annelida species.
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Affiliation(s)
- Jiali Liu
- Key Lab of Chinese Medicine Resources Conservation, State Administration of Traditional Chinese Medicine of the People's Republic of China, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100193, China Engineering Research Center of Chinese Medicine Resource, Ministry of Education, Beijing, 100193, China
| | - Jinxin Liu
- Key Lab of Chinese Medicine Resources Conservation, State Administration of Traditional Chinese Medicine of the People's Republic of China, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100193, China Engineering Research Center of Chinese Medicine Resource, Ministry of Education, Beijing, 100193, China
| | - Mingyue Li
- Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Lisi Zhou
- Key Lab of Chinese Medicine Resources Conservation, State Administration of Traditional Chinese Medicine of the People's Republic of China, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100193, China Engineering Research Center of Chinese Medicine Resource, Ministry of Education, Beijing, 100193, China
| | - Weijun Kong
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, 100069, China
| | - Hailin Zhang
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Medicine, School of Life Sciences and Technology, Tongji University, Shanghai, 200065, China
| | - Panpan Jin
- Key Lab of Chinese Medicine Resources Conservation, State Administration of Traditional Chinese Medicine of the People's Republic of China, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100193, China Engineering Research Center of Chinese Medicine Resource, Ministry of Education, Beijing, 100193, China
| | - Fuhua Lu
- Key Lab of Chinese Medicine Resources Conservation, State Administration of Traditional Chinese Medicine of the People's Republic of China, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100193, China Engineering Research Center of Chinese Medicine Resource, Ministry of Education, Beijing, 100193, China
| | - Gufa Lin
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Medicine, School of Life Sciences and Technology, Tongji University, Shanghai, 200065, China.
| | - Linchun Shi
- Key Lab of Chinese Medicine Resources Conservation, State Administration of Traditional Chinese Medicine of the People's Republic of China, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100193, China Engineering Research Center of Chinese Medicine Resource, Ministry of Education, Beijing, 100193, China.
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4
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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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5
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Bhattacharjee S, Iyer EPR, Iyer SC, Nanda S, Rubaharan M, Ascoli GA, Cox DN. The Zinc-BED Transcription Factor Bedwarfed Promotes Proportional Dendritic Growth and Branching through Transcriptional and Translational Regulation in Drosophila. Int J Mol Sci 2023; 24:6344. [PMID: 37047316 PMCID: PMC10094446 DOI: 10.3390/ijms24076344] [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: 02/21/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023] Open
Abstract
Dendrites are the primary points of sensory or synaptic input to a neuron and play an essential role in synaptic integration and neural function. Despite the functional importance of dendrites, relatively less is known about the underlying mechanisms regulating cell type-specific dendritic patterning. Herein, we have dissected the functional roles of a previously uncharacterized gene, CG3995, in cell type-specific dendritic development in Drosophila melanogaster. CG3995, which we have named bedwarfed (bdwf), encodes a zinc-finger BED-type protein that is required for proportional growth and branching of dendritic arbors. It also exhibits nucleocytoplasmic expression and functions in both transcriptional and translational cellular pathways. At the transcriptional level, we demonstrate a reciprocal regulatory relationship between Bdwf and the homeodomain transcription factor (TF) Cut. We show that Cut positively regulates Bdwf expression and that Bdwf acts as a downstream effector of Cut-mediated dendritic development, whereas overexpression of Bdwf negatively regulates Cut expression in multidendritic sensory neurons. Proteomic analyses revealed that Bdwf interacts with ribosomal proteins and disruption of these proteins resulted in phenotypically similar dendritic hypotrophy defects as observed in bdwf mutant neurons. We further demonstrate that Bdwf and its ribosomal protein interactors are required for normal microtubule and F-actin cytoskeletal architecture. Finally, our findings reveal that Bdwf is required to promote protein translation and ribosome trafficking along the dendritic arbor. These findings shed light on the complex, combinatorial, and multi-functional roles of transcription factors (TFs) in directing the diversification of cell type-specific dendritic development.
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Affiliation(s)
| | | | | | - Sumit Nanda
- Center for Neural Informatics, Structures, and Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
| | - Myurajan Rubaharan
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302, USA
| | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, and Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302, 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, Iyer EPR, Iyer SC, Nanda S, Rubaharan M, Ascoli GA, Cox DN. The Zinc-BED transcription factor Bedwarfed promotes proportional dendritic growth and branching through transcriptional and translational regulation in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.15.528686. [PMID: 36824896 PMCID: PMC9948997 DOI: 10.1101/2023.02.15.528686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Dendrites are the primary points of sensory or synaptic inputs to a neuron and play an essential role in synaptic integration and neural function. Despite the functional importance of dendrites, relatively less is known about the underlying mechanisms regulating cell-type specific dendritic patterning. Herein, we have dissected functional roles of a previously uncharacterized gene, CG3995 , in cell-type specific dendritic development in Drosophila melanogaster . CG3995 , which we have named bedwarfed ( bdwf ), encodes a zinc-finger BED-type protein which is required for proportional growth and branching of dendritic arbors, exhibits nucleocytoplasmic expression, and functions in both transcriptional and translational cellular pathways. At the transcriptional level, we demonstrate a reciprocal regulatory relationship between Bdwf and the homeodomain transcription factor (TF) Cut. We show that Cut positively regulates Bdwf expression and that Bdwf acts as a downstream effector of Cut-mediated dendritic development, whereas overexpression of Bdwf negatively regulates Cut expression in multidendritic sensory neurons. Proteomic analyses revealed that Bdwf interacts with ribosomal proteins and disruption of these proteins produced phenotypically similar dendritic hypotrophy defects as observed in bdwf mutant neurons. We further demonstrate that Bdwf and its ribosomal protein interactors are required for normal microtubule and F-actin cytoskeletal architecture. Finally, our findings reveal that Bdwf is required to promote protein translation and ribosome trafficking along the dendritic arbor. Taken together, these results provide new insights into the complex, combinatorial and multi-functional roles of transcription factors (TFs) in directing diversification of cell-type specific dendritic development.
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Affiliation(s)
| | | | | | - Sumit Nanda
- Center for Neural Informatics, Structures, & Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, 22030, USA
| | | | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, & Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, 22030, USA
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
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8
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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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Zeyn Y, Harms G, Tubbe I, Montermann E, Röhrig N, Hartmann M, Grabbe S, Bros M. Inhibitors of the Actin-Bundling Protein Fascin-1 Developed for Tumor Therapy Attenuate the T-Cell Stimulatory Properties of Dendritic Cells. Cancers (Basel) 2022; 14:cancers14112738. [PMID: 35681718 PMCID: PMC9179534 DOI: 10.3390/cancers14112738] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 05/28/2022] [Accepted: 05/29/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Expression of the actin-bundling protein Fascin-1 (Fscn1) is largely restricted to neuronal cells and to activated dendritic cells (DCs). DCs are important inducers of (antitumor) immune responses. In tumor cells, de novo expression of Fscn-1 correlates with their invasive and metastatic activities. Pharmacological Fscn1 inhibitors, which are currently under clinical trials for tumor therapy, were demonstrated to counteract tumor metastasis. Within this study, we were interested in better understanding the effects of Fscn1 inhibitors on DCs and discovered that two distinct Fascin-1 inhibitors affect the immune-phenotype and T-cell stimulatory activity of DCs. Our results suggest that systemic application of Fscn1 inhibitors for tumor therapy may also modulate antitumor immune responses. Abstract Background: Stimulated dendritic cells (DCs), which constitute the most potent population of antigen-presenting cells (APCs), express the actin-bundling protein Fascin-1 (Fscn1). In tumor cells, de novo expression of Fscn1 correlates with their invasive and metastatic properties. Therefore, Fscn1 inhibitors have been developed to serve as antitumor agents. In this study, we were interested in better understanding the impact of Fscn1 inhibitors on DCs. Methods: In parallel settings, murine spleen cells and bone-marrow-derived DCs (BMDCs) were stimulated with lipopolysaccharide in the presence of Fscn1 inhibitors (NP-G2-044 and BDP-13176). An analysis of surface expression of costimulatory and coinhibitory receptors, as well as cytokine production, was performed by flow cytometry. Cytoskeletal alterations were assessed by confocal microscopy. The effects on the interactions of BMDCs with antigen-specific T cells were monitored by time lapse microscopy. The T-cell stimulatory and polarizing capacity of BMDCs were measured in proliferation assays and cytokine studies. Results: Administration of Fscn1 inhibitors diminished Fscn1 expression and the formation of dendritic processes by stimulated BMDCs and elevated CD273 (PD-L2) expression. Fscn1 inhibition attenuated the interaction of DCs with antigen-specific T cells and concomitant T-cell proliferation. Conclusions: Systemic administration of Fscn1 inhibitors for tumor therapy may also modulate DC-induced antitumor immune responses.
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Affiliation(s)
- Yanira Zeyn
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
| | - Gregory Harms
- Cell Biology Unit, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany;
- Departments of Biology and Physics, Wilkes University, 84 W. South St., Wilkes Barre, PA 18766, USA
| | - Ingrid Tubbe
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
| | - Evelyn Montermann
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
| | - Nadine Röhrig
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
| | - Maike Hartmann
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
| | - Stephan Grabbe
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
| | - Matthias Bros
- Department of Dermatology, University Medical Center Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany; (Y.Z.); (I.T.); (E.M.); (N.R.); (M.H.); (S.G.)
- Correspondence: ; Tel.: +49-6131-17-9846
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10
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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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11
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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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12
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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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13
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Cordero Cervantes D, Zurzolo C. Peering into tunneling nanotubes-The path forward. EMBO J 2021; 40:e105789. [PMID: 33646572 PMCID: PMC8047439 DOI: 10.15252/embj.2020105789] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/21/2020] [Accepted: 01/15/2021] [Indexed: 12/19/2022] Open
Abstract
The identification of Tunneling Nanotubes (TNTs) and TNT-like structures signified a critical turning point in the field of cell-cell communication. With hypothesized roles in development and disease progression, TNTs' ability to transport biological cargo between distant cells has elevated these structures to a unique and privileged position among other mechanisms of intercellular communication. However, the field faces numerous challenges-some of the most pressing issues being the demonstration of TNTs in vivo and understanding how they form and function. Another stumbling block is represented by the vast disparity in structures classified as TNTs. In order to address this ambiguity, we propose a clear nomenclature and provide a comprehensive overview of the existing knowledge concerning TNTs. We also discuss their structure, formation-related pathways, biological function, as well as their proposed role in disease. Furthermore, we pinpoint gaps and dichotomies found across the field and highlight unexplored research avenues. Lastly, we review the methods employed to date and suggest the application of new technologies to better understand these elusive biological structures.
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Affiliation(s)
| | - Chiara Zurzolo
- Institut PasteurMembrane Traffic and PathogenesisParisFrance
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14
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Abstract
Neurons develop dendritic morphologies that bear cell type-specific features in dendritic field size and geometry, branch placement and density, and the types and distributions of synaptic contacts. Dendritic patterns influence the types and numbers of inputs a neuron receives, and the ways in which neural information is processed and transmitted in the circuitry. Even subtle alterations in dendritic structures can have profound consequences on neuronal function and are implicated in neurodevelopmental disorders. In this chapter, I review how growing dendrites acquire their exquisite patterns by drawing examples from diverse neuronal cell types in vertebrate and invertebrate model systems. Dendrite morphogenesis is shaped by intrinsic and extrinsic factors such as transcriptional regulators, guidance and adhesion molecules, neighboring cells and synaptic partners. I discuss molecular mechanisms that regulate dendrite morphogenesis with a focus on five aspects of dendrite patterning: (1) Dendritic cytoskeleton and cellular machineries that build the arbor; (2) Gene regulatory mechanisms; (3) Afferent cues that regulate dendritic arbor growth; (4) Space-filling strategies that optimize dendritic coverage; and (5) Molecular cues that specify dendrite wiring. Cell type-specific implementation of these patterning mechanisms produces the diversity of dendrite morphologies that wire the nervous system.
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15
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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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16
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Nanda S, Bhattacharjee S, Cox DN, Ascoli GA. Distinct Relations of Microtubules and Actin Filaments with Dendritic Architecture. iScience 2020; 23:101865. [PMID: 33319182 PMCID: PMC7725934 DOI: 10.1016/j.isci.2020.101865] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 09/09/2020] [Accepted: 11/20/2020] [Indexed: 12/15/2022] Open
Abstract
Microtubules (MTs) and F-actin (F-act) have long been recognized as key regulators of dendritic morphology. Nevertheless, precisely ascertaining their distinct influences on dendritic trees have been hampered until now by the lack of direct, arbor-wide cytoskeletal quantification. We pair live confocal imaging of fluorescently labeled dendritic arborization (da) neurons in Drosophila larvae with complete multi-signal neural tracing to separately measure MTs and F-act. We demonstrate that dendritic arbor length is highly interrelated with local MT quantity, whereas local F-act enrichment is associated with dendritic branching. Computational simulation of arbor structure solely constrained by experimentally observed subcellular distributions of these cytoskeletal components generated synthetic morphological and molecular patterns statistically equivalent to those of real da neurons, corroborating the efficacy of local MT and F-act in describing dendritic architecture. The analysis and modeling outcomes hold true for the simplest (class I), most complex (class IV), and genetically altered (Formin3 overexpression) da neuron types.
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Affiliation(s)
- Sumit Nanda
- Center for Neural Informatics, Structures, & Plasticity and Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
| | | | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, & Plasticity and Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, VA 22032, USA
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17
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Lamb MC, Tootle TL. Fascin in Cell Migration: More Than an Actin Bundling Protein. BIOLOGY 2020; 9:biology9110403. [PMID: 33212856 PMCID: PMC7698196 DOI: 10.3390/biology9110403] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022]
Abstract
Simple Summary Cell migration is an essential biological process that regulates both development and diseases, such as cancer metastasis. Therefore, understanding the factors that promote cell migration is crucial. One of the factors known to regulate cell migration is the actin-binding protein, Fascin. Fascin is typically thought to promote cell migration through bundling actin to form migratory structures such as filopodia and invadapodia. However, Fascin has many other functions in the cell that may contribute to cell migration. How these novel functions promote cell migration and are regulated is still not well understood. Here, we review the structure of Fascin, the many functions of Fascin and how they may promote cell migration, how Fascin is regulated, and Fascin’s role in diseases such as cancer metastasis. Abstract Fascin, an actin-binding protein, regulates many developmental migrations and contributes to cancer metastasis. Specifically, Fascin promotes cell motility, invasion, and adhesion by forming filopodia and invadopodia through its canonical actin bundling function. In addition to bundling actin, Fascin has non-canonical roles in the cell that are thought to promote cell migration. These non-canonical functions include regulating the activity of other actin-binding proteins, binding to and regulating microtubules, mediating mechanotransduction to the nucleus via interaction with the Linker of the Nucleoskeleton and Cytoskeleton (LINC) Complex, and localizing to the nucleus to regulate nuclear actin, the nucleolus, and chromatin modifications. The many functions of Fascin must be coordinately regulated to control cell migration. While much remains to be learned about such mechanisms, Fascin is regulated by post-translational modifications, prostaglandin signaling, protein–protein interactions, and transcriptional means. Here, we review the structure of Fascin, the various functions of Fascin and how they contribute to cell migration, the mechanisms regulating Fascin, and how Fascin contributes to diseases, specifically cancer metastasis.
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18
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Poe AR, Xu Y, Zhang C, Lei J, Li K, Labib D, Han C. Low FoxO expression in Drosophila somatosensory neurons protects dendrite growth under nutrient restriction. eLife 2020; 9:53351. [PMID: 32427101 PMCID: PMC7308081 DOI: 10.7554/elife.53351] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 05/18/2020] [Indexed: 12/22/2022] Open
Abstract
During prolonged nutrient restriction, developing animals redistribute vital nutrients to favor brain growth at the expense of other organs. In Drosophila, such brain sparing relies on a glia-derived growth factor to sustain proliferation of neural stem cells. However, whether other aspects of neural development are also spared under nutrient restriction is unknown. Here we show that dynamically growing somatosensory neurons in the Drosophila peripheral nervous system exhibit organ sparing at the level of arbor growth: Under nutrient stress, sensory dendrites preferentially grow as compared to neighboring non-neural tissues, resulting in dendrite overgrowth. These neurons express lower levels of the stress sensor FoxO than neighboring epidermal cells, and hence exhibit no marked induction of autophagy and a milder suppression of Tor signaling under nutrient stress. Preferential dendrite growth allows for heightened animal responses to sensory stimuli, indicative of a potential survival advantage under environmental challenges.
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Affiliation(s)
- Amy R Poe
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Yineng Xu
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Christine Zhang
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Joyce Lei
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Kailyn Li
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - David Labib
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Chun Han
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
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19
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Yoong LF, Lim HK, Tran H, Lackner S, Zheng Z, Hong P, Moore AW. Atypical Myosin Tunes Dendrite Arbor Subdivision. Neuron 2020; 106:452-467.e8. [DOI: 10.1016/j.neuron.2020.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 08/30/2019] [Accepted: 01/31/2020] [Indexed: 12/13/2022]
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20
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Abstract
Current understanding of the neuroanatomical abnormalities in autism includes gross anatomical changes in several brain areas and microstructural alterations in neuronal cells as well. There are many controversies in the interpretation of the imaging data, evaluation of volume and size of particular brain areas, and their functional translation into a broad autism phenotype. Critical questions of neuronal pathology in autism include the concept of the reversible plasticity of morphological changes, volume alterations of brain areas, and both short- and long-term consequences of adverse events present during the brain development. At the cellular level, remodeling of the actin cytoskeleton is considered as one of the critical factors associated with the autism spectrum disorders. Alterations in the composition of the neuronal cytoskeleton, in particular abnormalities in the polymerization of actin filaments and their associated proteins underlie the functional consequences in behavior resulting in symptoms and clinical correlates of autism spectrum disorder. In the present review, a special attention is devoted to the role of oxytocin in experimental models of neurodevelopmental disorders manifesting alterations in neuronal morphology.
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21
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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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22
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Wang Y, Rui M, Tang Q, Bu S, Yu F. Patronin governs minus-end-out orientation of dendritic microtubules to promote dendrite pruning in Drosophila. eLife 2019; 8:39964. [PMID: 30920370 PMCID: PMC6438692 DOI: 10.7554/elife.39964] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 03/08/2019] [Indexed: 01/09/2023] Open
Abstract
Class IV ddaC neurons specifically prune larval dendrites without affecting axons during Drosophila metamorphosis. ddaCs distribute the minus ends of microtubules (MTs) to dendrites but the plus ends to axons. However, a requirement of MT minus-end-binding proteins in dendrite-specific pruning remains completely unknown. Here, we identified Patronin, a minus-end-binding protein, for its crucial and dose-sensitive role in ddaC dendrite pruning. The CKK domain is important for Patronin’s function in dendrite pruning. Moreover, we show that both patronin knockdown and overexpression resulted in a drastic decrease of MT minus ends and a concomitant increase of plus-end-out MTs in ddaC dendrites, suggesting that Patronin stabilizes dendritic minus-end-out MTs. Consistently, attenuation of Klp10A MT depolymerase in patronin mutant neurons significantly restored minus-end-out MTs in dendrites and thereby rescued dendrite-pruning defects. Thus, our study demonstrates that Patronin orients minus-end-out MT arrays in dendrites to promote dendrite-specific pruning mainly through antagonizing Klp10A activity. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that minor issues remain unresolved (see decision letter).
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Affiliation(s)
- Yan Wang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
| | - Menglong Rui
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Quan Tang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shufeng Bu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore.,Neuroscience and Behavioral Disorder Program, Duke-NUS Graduate Medical School, National University of Singapore, Singapore, Singapore
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23
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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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24
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Clark SG, Graybeal LL, Bhattacharjee S, Thomas C, Bhattacharya S, Cox DN. Basal autophagy is required for promoting dendritic terminal branching in Drosophila sensory neurons. PLoS One 2018; 13:e0206743. [PMID: 30395636 PMCID: PMC6218061 DOI: 10.1371/journal.pone.0206743] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 10/18/2018] [Indexed: 01/22/2023] Open
Abstract
Dendrites function as the primary sites for synaptic input and integration with impairments in dendritic arborization being associated with dysfunctional neuronal circuitry. Post-mitotic neurons require high levels of basal autophagy to clear cytotoxic materials and autophagic dysfunction under native or cellular stress conditions has been linked to neuronal cell death as well as axo-dendritic degeneration. However, relatively little is known regarding the developmental role of basal autophagy in directing aspects of dendritic arborization or the mechanisms by which the autophagic machinery may be transcriptionally regulated to promote dendritic diversification. We demonstrate that autophagy-related (Atg) genes are positively regulated by the homeodomain transcription factor Cut, and that basal autophagy functions as a downstream effector pathway for Cut-mediated dendritic terminal branching in Drosophila multidendritic (md) sensory neurons. Further, loss of function analyses implicate Atg genes in promoting cell type-specific dendritic arborization and terminal branching, while gain of function studies suggest that excessive autophagy leads to dramatic reductions in dendritic complexity. We demonstrate that the Atg1 initiator kinase interacts with the dual leucine zipper kinase (DLK) pathway by negatively regulating the E3 ubiquitin ligase Highwire and positively regulating the MAPKKK Wallenda. Finally, autophagic induction partially rescues dendritic atrophy defects observed in a model of polyglutamine toxicity. Collectively, these studies implicate transcriptional control of basal autophagy in directing dendritic terminal branching and demonstrate the importance of homeostatic control of autophagic levels for dendritic arbor complexity under native or cellular stress conditions.
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Affiliation(s)
- Sarah G. Clark
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
| | - Lacey L. Graybeal
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
| | - Shatabdi Bhattacharjee
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
| | - Caroline Thomas
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
| | - Surajit Bhattacharya
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
- * E-mail:
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25
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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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26
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Fischer RS, Lam PY, Huttenlocher A, Waterman CM. Filopodia and focal adhesions: An integrated system driving branching morphogenesis in neuronal pathfinding and angiogenesis. Dev Biol 2018; 451:86-95. [PMID: 30193787 DOI: 10.1016/j.ydbio.2018.08.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/08/2018] [Accepted: 08/29/2018] [Indexed: 12/31/2022]
Abstract
Single cell branching during development in vertebrates is typified by neuronal branching to form neurites and vascular branches formed by sprouting angiogenesis. Neurons and endothelial tip cells possess subcellular protrusions that share many common features from the morphological to the molecular level. Both systems utilize filopodia as their cellular protrusion organelles and depend on specific integrin-mediated adhesions to the local extracellular matrix for guidance in their pathfinding. We discuss the similar molecular machineries involved in these two types of cell branch formation and use their analogy to propose a new mechanism for angiogenic filopodia function, namely as adhesion assembly sites. In support of this model we provide primary data of angiogenesis in zebrafish in vivo showing that the actin assembly factor VASP participates in both filopodia formation and adhesion assembly at the base of the filopodia, enabling forward progress of the tip cell. The use of filopodia and their associated adhesions provide a common mechanism for neuronal and endothelial pathfinding during development in response to extracellular matrix cues.
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Affiliation(s)
- Robert S Fischer
- Cell and Developmental Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, United States
| | - Pui-Ying Lam
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, United States
| | - Anna Huttenlocher
- Departments of Pediatrics and Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin, United States
| | - Clare M Waterman
- Cell and Developmental Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, United States.
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27
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Nithianandam V, Chien CT. Actin blobs prefigure dendrite branching sites. J Cell Biol 2018; 217:3731-3746. [PMID: 30042190 PMCID: PMC6168249 DOI: 10.1083/jcb.201711136] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/28/2018] [Accepted: 07/09/2018] [Indexed: 02/08/2023] Open
Abstract
Nithianandam and Chien show via in vivo imaging that a dynamic population of F-actin termed actin blobs propagates bidirectionally in dendrites and stalls at future branching sites. The F-actin–severing protein Tsr/cofilin is a regulator of actin blob dynamics and dendrite branching. The actin cytoskeleton provides structural stability and adaptability to the cell. Neuronal dendrites frequently undergo morphological changes by emanating, elongating, and withdrawing branches. However, the knowledge about actin dynamics in dendrites during these processes is limited. By performing in vivo imaging of F-actin markers, we found that F-actin was highly dynamic and heterogeneously distributed in dendritic shafts with enrichment at terminal dendrites. A dynamic F-actin population that we named actin blobs propagated bidirectionally at an average velocity of 1 µm/min. Interestingly, these actin blobs stalled at sites where new dendrites would branch out in minutes. Overstabilization of F-actin by the G15S mutant abolished actin blobs and dendrite branching. We identified the F-actin–severing protein Tsr/cofilin as a regulator of dynamic actin blobs and branching activity. Hence, actin blob localization at future branching sites represents a dendrite-branching mechanism to account for highly diversified dendritic morphology.
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Affiliation(s)
- Vanitha Nithianandam
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Cheng-Ting Chien
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan .,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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28
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Dendritic Cytoskeletal Architecture Is Modulated by Combinatorial Transcriptional Regulation in Drosophila melanogaster. Genetics 2017; 207:1401-1421. [PMID: 29025914 PMCID: PMC5714456 DOI: 10.1534/genetics.117.300393] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 10/04/2017] [Indexed: 01/08/2023] Open
Abstract
Transcription factors (TFs) have emerged as essential cell autonomous mediators of subtype specific dendritogenesis; however, the downstream effectors of these TFs remain largely unknown, as are the cellular events that TFs control to direct morphological change. As dendritic morphology is largely dictated by the organization of the actin and microtubule (MT) cytoskeletons, elucidating TF-mediated cytoskeletal regulatory programs is key to understanding molecular control of diverse dendritic morphologies. Previous studies in Drosophila melanogaster have demonstrated that the conserved TFs Cut and Knot exert combinatorial control over aspects of dendritic cytoskeleton development, promoting actin and MT-based arbor morphology, respectively. To investigate transcriptional targets of Cut and/or Knot regulation, we conducted systematic neurogenomic studies, coupled with in vivo genetic screens utilizing multi-fluor cytoskeletal and membrane marker reporters. These analyses identified a host of putative Cut and/or Knot effector molecules, and a subset of these putative TF targets converge on modulating dendritic cytoskeletal architecture, which are grouped into three major phenotypic categories, based upon neuromorphometric analyses: complexity enhancer, complexity shifter, and complexity suppressor. Complexity enhancer genes normally function to promote higher order dendritic growth and branching with variable effects on MT stabilization and F-actin organization, whereas complexity shifter and complexity suppressor genes normally function in regulating proximal-distal branching distribution or in restricting higher order branching complexity, respectively, with spatially restricted impacts on the dendritic cytoskeleton. Collectively, we implicate novel genes and cellular programs by which TFs distinctly and combinatorially govern dendritogenesis via cytoskeletal modulation.
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Wang B, Fan B, Dai Q, Xu X, Jiang P, Zhu L, Dai H, Yao Z, Xu Z, Liu X. Fascin-1 Contributes to Neuropathic Pain by Promoting Inflammation in Rat Spinal Cord. Neurochem Res 2017; 43:287-296. [PMID: 29052088 DOI: 10.1007/s11064-017-2420-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/17/2017] [Accepted: 10/13/2017] [Indexed: 12/27/2022]
Abstract
Neuropathic pain is a complicated clinical syndrome caused by heterogeneous etiology. Despite the fact that the underlying mechanisms remain elusive, it is well accepted that neuroinflammation plays a critical role in the development of neuropathic pain. Fascin-1, an actin-bundling protein, has been proved to be involved in the processing of diverse biological events including cellular development, immunity, and tumor invasion etc. Recent studies have shown that Fascin-1 participates in antigen presentation and the regulation of pro-inflammatory agents. However, whether Fascin-1 is involved in neuropathic pain has not been reported. In the present study we examined the potential role of Fascin-1 by using a rodent model of chronic constriction injury (CCI). Our results showed that Fascin-1 increased rapidly in dorsal root ganglions (DRG) and spinal cord (SC) after CCI. The increased Fascin-1 widely expressed in DRG, however, it localized predominantly in microglia, seldom in neuron, and hardly in astrocyte in the SC. Intrathecal injection of Fascin-1 siRNA not only suppressed the activation of microglia and the release of pro-inflammatory mediators, but also attenuated the mechanical allodynia and thermal hyperalgesia induced by CCI.
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Affiliation(s)
- Binbin Wang
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China
| | - Bingbing Fan
- Department of Radiology, Zhongshan Hospital and Shanghai Institute of Medical Imaging, Department of Medical Imaging, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Qijun Dai
- Nanjing University of Traditional Chinese Medicine Hanlin College Affiliated Hai'an Chinese Medicine Hospital, Nanjing University of Traditional Chinese Medicine, Haian, Jiangsu, China
| | - Xingguo Xu
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China
| | - Peipei Jiang
- Nanjing University of Traditional Chinese Medicine Hanlin College Affiliated Hai'an Chinese Medicine Hospital, Nanjing University of Traditional Chinese Medicine, Haian, Jiangsu, China
| | - Lin Zhu
- Nanjing University of Traditional Chinese Medicine Hanlin College Affiliated Hai'an Chinese Medicine Hospital, Nanjing University of Traditional Chinese Medicine, Haian, Jiangsu, China
| | - Haifeng Dai
- Nanjing University of Traditional Chinese Medicine Hanlin College Affiliated Hai'an Chinese Medicine Hospital, Nanjing University of Traditional Chinese Medicine, Haian, Jiangsu, China
| | - Zhigang Yao
- Nanjing University of Traditional Chinese Medicine Hanlin College Affiliated Hai'an Chinese Medicine Hospital, Nanjing University of Traditional Chinese Medicine, Haian, Jiangsu, China
| | - Zhongling Xu
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China.
| | - Xiaojuan Liu
- Department of Pathogen Biology, Medical College, Nantong University, Nantong, 2266001, Jiangsu, China.
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Sears JC, Broihier HT. FoxO regulates microtubule dynamics and polarity to promote dendrite branching in Drosophila sensory neurons. Dev Biol 2016; 418:40-54. [PMID: 27546375 DOI: 10.1016/j.ydbio.2016.08.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 01/15/2023]
Abstract
The size and shape of dendrite arbors are defining features of neurons and critical determinants of neuronal function. The molecular mechanisms establishing arborization patterns during development are not well understood, though properly regulated microtubule (MT) dynamics and polarity are essential. We previously found that FoxO regulates axonal MTs, raising the question of whether it also regulates dendritic MTs and morphology. Here we demonstrate that FoxO promotes dendrite branching in all classes of Drosophila dendritic arborization (da) neurons. FoxO is required both for initiating growth of new branches and for maintaining existing branches. To elucidate FoxO function, we characterized MT organization in both foxO null and overexpressing neurons. We find that FoxO directs MT organization and dynamics in dendrites. Moreover, it is both necessary and sufficient for anterograde MT polymerization, which is known to promote dendrite branching. Lastly, FoxO promotes proper larval nociception, indicating a functional consequence of impaired da neuron morphology in foxO mutants. Together, our results indicate that FoxO regulates dendrite structure and function and suggest that FoxO-mediated pathways control MT dynamics and polarity.
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Affiliation(s)
- James C Sears
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Heather T Broihier
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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31
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Ori-McKenney KM, McKenney RJ, Huang HH, Li T, Meltzer S, Jan LY, Vale RD, Wiita AP, Jan YN. Phosphorylation of β-Tubulin by the Down Syndrome Kinase, Minibrain/DYRK1a, Regulates Microtubule Dynamics and Dendrite Morphogenesis. Neuron 2016; 90:551-63. [PMID: 27112495 DOI: 10.1016/j.neuron.2016.03.027] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 02/02/2016] [Accepted: 03/16/2016] [Indexed: 12/31/2022]
Abstract
Dendritic arborization patterns are consistent anatomical correlates of genetic disorders such as Down syndrome (DS) and autism spectrum disorders (ASDs). In a screen for abnormal dendrite development, we identified Minibrain (MNB)/DYRK1a, a kinase implicated in DS and ASDs, as a regulator of the microtubule cytoskeleton. We show that MNB is necessary to establish the length and cytoskeletal composition of terminal dendrites by controlling microtubule growth. Altering MNB levels disrupts dendrite morphology and perturbs neuronal electrophysiological activity, resulting in larval mechanosensation defects. Using in vivo and in vitro approaches, we uncover a molecular pathway whereby direct phosphorylation of β-tubulin by MNB inhibits tubulin polymerization, a function that is conserved for mammalian DYRK1a. Our results demonstrate that phosphoregulation of microtubule dynamics by MNB/DYRK1a is critical for dendritic patterning and neuronal function, revealing a previously unidentified mode of posttranslational microtubule regulation in neurons and uncovering a conserved pathway for a DS- and ASD-associated kinase.
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Affiliation(s)
- Kassandra M Ori-McKenney
- Department of Physiology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Richard J McKenney
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Hector H Huang
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tun Li
- Department of Physiology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Shan Meltzer
- Department of Physiology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lily Yeh Jan
- Department of Physiology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Arun P Wiita
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuh Nung Jan
- Department of Physiology and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
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32
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Abstract
Dendrite branching is an essential process for building complex nervous systems. It determines the number, distribution and integration of inputs into a neuron, and is regulated to create the diverse dendrite arbor branching patterns characteristic of different neuron types. The microtubule cytoskeleton is critical to provide structure and exert force during dendrite branching. It also supports the functional requirements of dendrites, reflected by differential microtubule architectural organization between neuron types, illustrated here for sensory neurons. Both anterograde and retrograde microtubule polymerization occur within growing dendrites, and recent studies indicate that branching is enhanced by anterograde microtubule polymerization events in nascent branches. The polarities of microtubule polymerization events are regulated by the position and orientation of microtubule nucleation events in the dendrite arbor. Golgi outposts are a primary microtubule nucleation center in dendrites and share common nucleation machinery with the centrosome. In addition, pre-existing dendrite microtubules may act as nucleation sites. We discuss how balancing the activities of distinct nucleation machineries within the growing dendrite can alter microtubule polymerization polarity and dendrite branching, and how regulating this balance can generate neuron type-specific morphologies.
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Affiliation(s)
- Caroline Delandre
- a Laboratory for Genetic Control of Neuronal Architecture, RIKEN Brain Science Institute , Wako , Saitama , Japan
| | - Reiko Amikura
- a Laboratory for Genetic Control of Neuronal Architecture, RIKEN Brain Science Institute , Wako , Saitama , Japan
| | - Adrian W Moore
- a Laboratory for Genetic Control of Neuronal Architecture, RIKEN Brain Science Institute , Wako , Saitama , Japan
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Menon S, Gupton SL. Building Blocks of Functioning Brain: Cytoskeletal Dynamics in Neuronal Development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:183-245. [PMID: 26940519 PMCID: PMC4809367 DOI: 10.1016/bs.ircmb.2015.10.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neural connectivity requires proper polarization of neurons, guidance to appropriate target locations, and establishment of synaptic connections. From when neurons are born to when they finally reach their synaptic partners, neurons undergo constant rearrangment of the cytoskeleton to achieve appropriate shape and polarity. Of particular importance to neuronal guidance to target locations is the growth cone at the tip of the axon. Growth-cone steering is also dictated by the underlying cytoskeleton. All these changes require spatiotemporal control of the cytoskeletal machinery. This review summarizes the proteins that are involved in modulating the actin and microtubule cytoskeleton during the various stages of neuronal development.
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Affiliation(s)
- Shalini Menon
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America; Neuroscience Center and Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC, United States of America; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America.
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34
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Ma Y, Machesky LM. Fascin1 in carcinomas: Its regulation and prognostic value. Int J Cancer 2015; 137:2534-44. [PMID: 25302416 DOI: 10.1002/ijc.29260] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 10/01/2014] [Indexed: 01/06/2023]
Abstract
Previous cell biological studies demonstrate that the actin bundling protein fascin1 regulates cell motility, migration and invasion. Human studies demonstrate that fascin1 is upregulated in many epithelial cancers. This review gives a brief overview of the role of fascin1 in cell migration and invasion, but focuses mainly on the regulation and clinical relevance of fascin1 in epithelial cancers. Here, we propose fascin1 as a potent prognostic biomarker for breast, colorectal, esophageal cancers and head and neck squamous cell carcinomas. Fascin1 may also be an attractive drug target against these carcinomas in the future, but more studies are needed.
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Affiliation(s)
- Yafeng Ma
- School of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- Medical Oncology Group, Ingham Institute for Applied Medical Research, Liverpool, NSW2170, New South Wales, Australia
| | - Laura M Machesky
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD, Scotland, United Kingdom
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35
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Abstract
The nervous system is populated by numerous types of neurons, each bearing a dendritic arbor with a characteristic morphology. These type-specific features influence many aspects of a neuron's function, including the number and identity of presynaptic inputs and how inputs are integrated to determine firing properties. Here, we review the mechanisms that regulate the construction of cell type-specific dendrite patterns during development. We focus on four aspects of dendrite patterning that are particularly important in determining the function of the mature neuron: (a) dendrite shape, including branching pattern and geometry of the arbor; (b) dendritic arbor size;
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Affiliation(s)
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138;
| | - Jeremy N Kay
- Departments of Neurobiology and Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27710;
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36
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Bauke AC, Sasse S, Matzat T, Klämbt C. A transcriptional network controlling glial development in the Drosophila visual system. Development 2015; 142:2184-93. [DOI: 10.1242/dev.119750] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 04/28/2015] [Indexed: 01/07/2023]
Abstract
In the nervous system, glial cells need to be specified from a set of progenitor cells. In the developing Drosophila eye, perineurial glia proliferate and differentiate as wrapping glia in response to a neuronal signal conveyed by the FGF receptor pathway. To unravel the underlying transcriptional network we silenced all genes encoding predicted DNA-binding proteins in glial cells using RNAi. Dref and other factors of the TATA box-binding protein-related factor 2 (TRF2) complex were previously predicted to be involved in cellular metabolism and cell growth. Silencing of these genes impaired early glia proliferation and subsequent differentiation. Dref controls proliferation via activation of the Pdm3 transcription factor, whereas glial differentiation is regulated via Dref and the homeodomain protein Cut. Cut expression is controlled independently of Dref by FGF receptor activity. Loss- and gain-of-function studies show that Cut is required for glial differentiation and is sufficient to instruct the formation of membrane protrusions, a hallmark of wrapping glial morphology. Our work discloses a network of transcriptional regulators controlling the progression of a naïve perineurial glia towards the fully differentiated wrapping glia.
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Affiliation(s)
- Ann-Christin Bauke
- Institute of Neurobiology, University of Münster, Münster 48149, Germany
| | - Sofia Sasse
- Institute of Neurobiology, University of Münster, Münster 48149, Germany
| | - Till Matzat
- Institute of Neurobiology, University of Münster, Münster 48149, Germany
| | - Christian Klämbt
- Institute of Neurobiology, University of Münster, Münster 48149, Germany
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37
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Case of 7p22.1 Microduplication Detected by Whole Genome Microarray (REVEAL) in Workup of Child Diagnosed with Autism. Case Rep Genet 2015; 2015:212436. [PMID: 25893121 PMCID: PMC4393924 DOI: 10.1155/2015/212436] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 02/01/2015] [Accepted: 03/06/2015] [Indexed: 01/03/2023] Open
Abstract
Introduction. More than 60 cases of 7p22 duplications and deletions have been reported with over 16 of them occurring without concomitant chromosomal abnormalities. Patient and Methods. We report a 29-month-old male diagnosed with autism. Whole genome chromosome SNP microarray (REVEAL) demonstrated a 1.3 Mb interstitial duplication of 7p22.1 ->p22.1 arr 7p22.1 (5,436,367-6,762,394), the second smallest interstitial 7p duplication reported to date. This interval included 14 OMIM annotated genes (FBXL18, ACTB, FSCN1, RNF216, OCM, EIF2AK1, AIMP2, PMS2, CYTH3, RAC1, DAGLB, KDELR2, GRID2IP, and ZNF12). Results. Our patient presented features similar to previously reported cases with 7p22 duplication, including brachycephaly, prominent ears, cryptorchidism, speech delay, poor eye contact, and outburst of aggressive behavior with autism-like features. Among the genes located in the duplicated segment, ACTB gene has been proposed as a candidate gene for the alteration of craniofacial development. Overexpression of RNF216L has been linked to autism. FSCN1 may play a role in neurodevelopmental disease. Conclusion. Characterization of a possible 7p22.1 Duplication Syndrome has yet to be made. Recognition of the clinical spectrum in patients with a smaller duplication of 7p should prove valuable for determining the minimal critical region, helping delineate a better prediction of outcome and genetic counseling.
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38
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Santiago C, Bashaw GJ. Transcription factors and effectors that regulate neuronal morphology. Development 2015; 141:4667-80. [PMID: 25468936 DOI: 10.1242/dev.110817] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Transcription factors establish the tremendous diversity of cell types in the nervous system by regulating the expression of genes that give a cell its morphological and functional properties. Although many studies have identified requirements for specific transcription factors during the different steps of neural circuit assembly, few have identified the downstream effectors by which they control neuronal morphology. In this Review, we highlight recent work that has elucidated the functional relationships between transcription factors and the downstream effectors through which they regulate neural connectivity in multiple model systems, with a focus on axon guidance and dendrite morphogenesis.
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Affiliation(s)
- Celine Santiago
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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39
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Okenve-Ramos P, Llimargas M. A role for fascin in preventing filopodia breakage in Drosophila tracheal cells. Commun Integr Biol 2014; 7:972846. [PMID: 26843903 PMCID: PMC4594546 DOI: 10.4161/cib.29741] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 06/26/2014] [Indexed: 11/19/2022] Open
Abstract
Filopodia are long and thin finger-like protrusions essential for cell migration. They
are formed by parallel actin bundles tightly packed by cell type and context dependent
actin-bundling proteins. Our recent work analyzing the role of Fascin during tracheal
development in Drosophila has shown that Singed (the
Drosophila Fascin homolog) acts as a molecular link between the
Branchless (FGF)/Breathless (FGFR) pathway and the actin cytoskeleton. We have reported
that the lack of Singed (Sn) leads to wavy and flaccid filopodia due to the
disorganization of the tracheal actin cytoskeleton. Here we describe for the first time
filopodia breakage in Drosophila, and show that Fascin plays a role in
this event. We propose that actin filaments in sn mutant filopodia buckle under membrane
pressure due to lower bending stiffness, eventually undergoing breakage. Both Filopodia
buckling and breakage would impair correct cell navigation and migration.
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Affiliation(s)
| | - Marta Llimargas
- Institute of Molecular Biology of Barcelona (CSIC) ; Barcelona, Spain
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40
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Wei Z, Sun M, Liu X, Zhang J, Jin Y. Rufy3, a protein specifically expressed in neurons, interacts with actin-bundling protein Fascin to control the growth of axons. J Neurochem 2014; 130:678-92. [PMID: 24720729 DOI: 10.1111/jnc.12740] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 04/02/2014] [Accepted: 04/07/2014] [Indexed: 01/10/2023]
Abstract
For our nervous system to function properly, each neuron must generate a single axon and elongate the axon to reach its target. It is known that actin filaments and their dynamic interaction with microtubules within growth cones play important roles in inducing axon extension. However, it remains unclear how cytoskeletal dynamics is controlled in growth cones. In this study, we report that Rufy3, a RUN domain-containing protein, is a neuron-specific and actin filament-relevant protein. We find that the appropriate expression of Rufy3 in mouse hippocampal neurons is required for the development of a single axon and axon growth. Our results show that Rufy3 specifically interacts with actin filament-binding proteins, such as Fascin, and colocalizes with Fascin in growth cones. Knockdown of Rufy3 impairs the distribution of Fascin and actin filaments, accompanied by an increased proportion of neurons with multiple axons and a decrease in the axon length. Therefore, Rufy3 may be particularly important for neuronal axon elongation by interacting with Fascin to control actin filament organization in axonal growth cones. We propose that Rufy3 may control mouse neuron axon development through its specific interaction with Fascin and Drebrin. Over-expression of Rufy3 (Rufy3 OE) leads to longer axons and expands the distribution of Drebrin to almost the entire growth cone. In contrast, knockdown of Rufy3 (Rufy3 RNAi) results in shortened axons and enhanced the percentage of mutipolar neurons. Moreover, silencing of Rufy3 reduces and restricts the expression of Fascin and F-actin to the edge of the growth cone. These findings provide new insights into the molecular regulation of axonal outgrowth and cell polarization in neurons.
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Affiliation(s)
- Zhe Wei
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
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41
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Singhania A, Grueber WB. Development of the embryonic and larval peripheral nervous system of Drosophila. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 3:193-210. [PMID: 24896657 DOI: 10.1002/wdev.135] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 02/19/2014] [Accepted: 03/05/2014] [Indexed: 01/01/2023]
Abstract
The peripheral nervous system (PNS) of embryonic and larval stage Drosophila consists of diverse types of sensory neurons positioned along the body wall. Sensory neurons, and associated end organs, show highly stereotyped locations and morphologies. Many powerful genetic tools for gene manipulation available in Drosophila make the PNS an advantageous system for elucidating basic principles of neural development. Studies of the Drosophila PNS have provided key insights into molecular mechanisms of cell fate specification, asymmetric cell division, and dendritic morphogenesis. A canonical lineage gives rise to sensory neurons and associated organs, and cells within this lineage are diversified through asymmetric cell divisions. Newly specified sensory neurons develop specific dendritic patterns, which are controlled by numerous factors including transcriptional regulators, interactions with neighboring neurons, and intracellular trafficking systems. In addition, sensory axons show modality specific terminations in the central nervous system, which are patterned by secreted ligands and their receptors expressed by sensory axons. Modality-specific axon projections are critical for coordinated larval behaviors. We review the molecular basis for PNS development and address some of the instances in which the mechanisms and molecules identified are conserved in vertebrate development.
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Affiliation(s)
- Aditi Singhania
- Department of Genetics and Development, Columbia University Medical Center, New York, NY, USA
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42
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Okenve-Ramos P, Llimargas M. Fascin links Btl/FGFR signalling to the actin cytoskeleton during Drosophila tracheal morphogenesis. Development 2014; 141:929-39. [PMID: 24496629 DOI: 10.1242/dev.103218] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A key challenge in normal development and in disease is to elucidate the mechanisms of cell migration. Here we approach this question using the tracheal system of Drosophila as a model. Tracheal cell migration requires the Breathless/FGFR pathway; however, how the pathway induces migration remains poorly understood. We find that the Breathless pathway upregulates singed at the tip of tracheal branches, and that this regulation is functionally relevant. singed encodes Drosophila Fascin, which belongs to a conserved family of actin-bundling proteins involved in cancer progression and metastasis upon misregulation. We show that singed is required for filopodia stiffness and proper morphology of tracheal tip cells, defects that correlate with an abnormal actin organisation. We propose that singed-regulated filopodia and cell fronts are required for timely and guided branch migration and for terminal branching and branch fusion. We find that singed requirements rely on its actin-bundling activity controlled by phosphorylation, and that active Singed can promote tip cell features. Furthermore, we find that singed acts in concert with forked, another actin cross-linker. The absence of both cross-linkers further stresses the relevance of tip cell morphology and filopodia for tracheal development. In summary, our results on the one hand reveal a previously undescribed role for forked in the organisation of transient actin structures such as filopodia, and on the other hand identify singed as a new target of Breathless signal, establishing a link between guidance cues, the actin cytoskeleton and tracheal morphogenesis.
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Affiliation(s)
- Pilar Okenve-Ramos
- Institut de Biologia Molecular de Barcelona, CSIC, Parc Científic de Barcelona, Baldiri Reixac, 4-8, 08028 Barcelona, Spain
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43
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Ferreira T, Ou Y, Li S, Giniger E, van Meyel DJ. Dendrite architecture organized by transcriptional control of the F-actin nucleator Spire. Development 2014; 141:650-60. [PMID: 24449841 DOI: 10.1242/dev.099655] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The architectures of dendritic trees are crucial for the wiring and function of neuronal circuits because they determine coverage of receptive territories, as well as the nature and strength of sensory or synaptic inputs. Here, we describe a cell-intrinsic pathway sculpting dendritic arborization (da) neurons in Drosophila that requires Longitudinals Lacking (Lola), a BTB/POZ transcription factor, and its control of the F-actin cytoskeleton through Spire (Spir), an actin nucleation protein. Loss of Lola from da neurons reduced the overall length of dendritic arbors, increased the expression of Spir, and produced inappropriate F-actin-rich dendrites at positions too near the cell soma. Selective removal of Lola from only class IV da neurons decreased the evasive responses of larvae to nociception. The increased Spir expression contributed to the abnormal F-actin-rich dendrites and the decreased nocifensive responses because both were suppressed by reduced dose of Spir. Thus, an important role of Lola is to limit expression of Spir to appropriate levels within da neurons. We found Spir to be expressed in dendritic arbors and to be important for their development. Removal of Spir from class IV da neurons reduced F-actin levels and total branch number, shifted the position of greatest branch density away from the cell soma, and compromised nocifensive behavior. We conclude that the Lola-Spir pathway is crucial for the spatial arrangement of branches within dendritic trees and for neural circuit function because it provides balanced control of the F-actin cytoskeleton.
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Affiliation(s)
- Tiago Ferreira
- McGill Centre for Research in Neuroscience, McGill University Health Centre, 1650 Cedar Avenue, Montreal, QC H3G 1A4, Canada
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44
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Abstract
The proper formation and morphogenesis of dendrites is fundamental to the establishment of neural circuits in the brain. Following cell cycle exit and migration, neurons undergo organized stages of dendrite morphogenesis, which include dendritic arbor growth and elaboration followed by retraction and pruning. Although these developmental stages were characterized over a century ago, molecular regulators of dendrite morphogenesis have only recently been defined. In particular, studies in Drosophila and mammalian neurons have identified numerous cell-intrinsic drivers of dendrite morphogenesis that include transcriptional regulators, cytoskeletal and motor proteins, secretory and endocytic pathways, cell cycle-regulated ubiquitin ligases, and components of other signaling cascades. Here, we review cell-intrinsic drivers of dendrite patterning and discuss how the characterization of such crucial regulators advances our understanding of normal brain development and pathogenesis of diverse cognitive disorders.
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Affiliation(s)
- Sidharth V Puram
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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45
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Zupanc GKH, Ilies I, Sîrbulescu RF, Zupanc MM. Large-scale identification of proteins involved in the development of a sexually dimorphic behavior. J Neurophysiol 2014; 111:1646-54. [PMID: 24478160 DOI: 10.1152/jn.00750.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sexually dimorphic behaviors develop under the influence of sex steroids, which induce reversible changes in the underlying neural network of the brain. However, little is known about the proteins that mediate these activational effects of sex steroids. Here, we used a proteomics approach for large-scale identification of proteins involved in the development of a sexually dimorphic behavior, the electric organ discharge of brown ghost knifefish, Apteronotus leptorhynchus. In this weakly electric fish, the discharge frequency is controlled by the medullary pacemaker nucleus and is higher in males than in females. After lowering the discharge frequency by chronic administration of β-estradiol, 2-dimensional difference gel electrophoresis revealed 62 proteins spots in tissue samples from the pacemaker nucleus that exhibited significant changes in abundance of >1.5-fold. The 20 identified protein spots indicated, among others, a potential involvement of astrocytes in the establishment of the behavioral dimorphism. Indeed, immunohistochemical analysis demonstrated higher expression of the astrocytic marker protein GFAP and increased gap-junction coupling between astrocytes in females compared with males. We hypothesize that changes in the size of the glial syncytium, glial coupling, and/or number of glia-specific potassium channels lead to alterations in the firing frequency of the pacemaker nucleus via a mechanism mediating the uptake of extracellular potassium ions from the extracellular space.
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Affiliation(s)
- Günther K H Zupanc
- Department of Biology, Northeastern University, Boston, Massachusetts; and
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Iyer SC, Ramachandran Iyer EP, Meduri R, Rubaharan M, Kuntimaddi A, Karamsetty M, Cox DN. Cut, via CrebA, transcriptionally regulates the COPII secretory pathway to direct dendrite development in Drosophila. J Cell Sci 2013; 126:4732-45. [PMID: 23902691 DOI: 10.1242/jcs.131144] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Dendrite development is crucial in the formation of functional neural networks. Recent studies have provided insights into the involvement of secretory transport in dendritogenesis, raising the question of how the secretory pathway is controlled to direct dendritic elaboration. Here, we identify a functional link between transcriptional regulatory programs and the COPII secretory machinery in driving dendrite morphogenesis in Drosophila dendritic arborization (da) sensory neurons. MARCM analyses and gain-of-function studies reveal cell-autonomous requirements for the COPII coat protein Sec31 in mediating da neuron dendritic homeostasis. We demonstrate that the homeodomain protein Cut transcriptionally regulates Sec31 in addition to other components of COPII secretory transport, to promote dendrite elaboration, accompanied by increased satellite secretory endoplasmic reticulum (ER) and Golgi outposts primarily localized to dendritic branch points. We further establish a novel functional role for the transcription factor CrebA in regulating dendrite development and show that Cut initiates a gene expression cascade through CrebA that coordinately affects the COPII machinery to mediate dendritic morphology.
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Sonego M, Gajendra S, Parsons M, Ma Y, Hobbs C, Zentar MP, Williams G, Machesky LM, Doherty P, Lalli G. Fascin regulates the migration of subventricular zone-derived neuroblasts in the postnatal brain. J Neurosci 2013; 33:12171-85. [PMID: 23884926 PMCID: PMC3721833 DOI: 10.1523/jneurosci.0653-13.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/17/2013] [Accepted: 06/08/2013] [Indexed: 01/01/2023] Open
Abstract
After birth, stem cells in the subventricular zone (SVZ) generate neuroblasts that migrate along the rostral migratory stream (RMS) to become interneurons in the olfactory bulb (OB). This migration is a fundamental event controlling the proper integration of new neurons in a pre-existing synaptic network. Many regulators of neuroblast migration have been identified; however, still very little is known about the intracellular molecular mechanisms controlling this process. Here, we show that the actin-bundling protein fascin is highly upregulated in mouse SVZ-derived migratory neuroblasts. Fascin-1ko mice display an abnormal RMS and a smaller OB. Bromodeoxyuridine labeling experiments show that lack of fascin significantly impairs neuroblast migration, but does not appear to affect cell proliferation. Moreover, fascin depletion substantially alters the polarized morphology of rat neuroblasts. Protein kinase C (PKC)-dependent phosphorylation of fascin on Ser39 regulates its actin-bundling activity. In vivo postnatal electroporation of phosphomimetic (S39D) or nonphosphorylatable (S39A) fascin variants followed by time-lapse imaging of brain slices demonstrates that the phospho-dependent modulation of fascin activity ensures efficient neuroblast migration. Finally, fluorescence lifetime imaging microscopy studies in rat neuroblasts reveal that the interaction between fascin and PKC can be modulated by cannabinoid signaling, which controls neuroblast migration in vivo. We conclude that fascin, whose upregulation appears to mark the transition to the migratory neuroblast stage, is a crucial regulator of neuroblast motility. We propose that a tightly regulated phospho/dephospho-fascin cycle modulated by extracellular signals is required for the polarized morphology and migration in neuroblasts, thus contributing to efficient neurogenesis.
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Affiliation(s)
| | | | - Maddy Parsons
- Randall Division, King's College London, Guy's Campus, London SE1 1UL, United Kingdom, and
| | - Yafeng Ma
- Beatson Institute for Cancer Research, Glasgow University College of Medical, Veterinary and Life Sciences, Garscube Estate, Bearsden, Glasgow G61 1BD, United Kingdom
| | - Carl Hobbs
- Wolfson Centre for Age-Related Diseases, and
| | | | | | - Laura M. Machesky
- Beatson Institute for Cancer Research, Glasgow University College of Medical, Veterinary and Life Sciences, Garscube Estate, Bearsden, Glasgow G61 1BD, United Kingdom
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