1
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Aksan B, Kenkel AK, Yan J, Sánchez Romero J, Missirlis D, Mauceri D. VEGFD signaling balances stability and activity-dependent structural plasticity of dendrites. Cell Mol Life Sci 2024; 81:354. [PMID: 39158743 PMCID: PMC11335284 DOI: 10.1007/s00018-024-05357-2] [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: 05/24/2024] [Revised: 07/08/2024] [Accepted: 07/09/2024] [Indexed: 08/20/2024]
Abstract
Mature neurons have stable dendritic architecture, which is essential for the nervous system to operate correctly. The ability to undergo structural plasticity, required to support adaptive processes like memory formation, is still present in mature neurons. It is unclear what molecular and cellular processes control this delicate balance between dendritic structural plasticity and stabilization. Failures in the preservation of optimal dendrite structure due to atrophy or maladaptive plasticity result in abnormal connectivity and are associated with various neurological diseases. Vascular endothelial growth factor D (VEGFD) is critical for the maintenance of mature dendritic trees. Here, we describe how VEGFD affects the neuronal cytoskeleton and demonstrate that VEGFD exerts its effects on dendrite stabilization by influencing the actin cortex and reducing microtubule dynamics. Further, we found that during synaptic activity-induced structural plasticity VEGFD is downregulated. Our findings revealed that VEGFD, acting on its cognate receptor VEGFR3, opposes structural changes by negatively regulating dendrite growth in cultured hippocampal neurons and in vivo in the adult mouse hippocampus with consequences on memory formation. A phosphoproteomic screening identified several regulatory proteins of the cytoskeleton modulated by VEGFD. Among the actin cortex-associated proteins, we found that VEGFD induces dephosphorylation of ezrin at tyrosine 478 via activation of the striatal-enriched protein tyrosine phosphatase (STEP). Activity-triggered structural plasticity of dendrites was impaired by expression of a phospho-deficient mutant ezrin in vitro and in vivo. Thus, VEGFD governs the equilibrium between stabilization and plasticity of dendrites by acting as a molecular brake of structural remodeling.
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Affiliation(s)
- Bahar Aksan
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences (IZN), Heidelberg University, INF 366, 69120, Heidelberg, Germany
| | - Ann-Kristin Kenkel
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences (IZN), Heidelberg University, INF 366, 69120, Heidelberg, Germany
| | - Jing Yan
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences (IZN), Heidelberg University, INF 366, 69120, Heidelberg, Germany
| | - Javier Sánchez Romero
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences (IZN), Heidelberg University, INF 366, 69120, Heidelberg, Germany
| | - Dimitris Missirlis
- Department of Cellular Biophysics, Max-Planck-Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Daniela Mauceri
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences (IZN), Heidelberg University, INF 366, 69120, Heidelberg, Germany.
- Department Molecular and Cellular Neuroscience, Institute of Anatomy and Cell Biology, University of Marburg, Robert-Koch-Str. 8, 35032, Marburg, Germany.
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2
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Nelson AC, Rolls MM, Ciocanel MV, McKinley SA. Minimal Mechanisms of Microtubule Length Regulation in Living Cells. Bull Math Biol 2024; 86:58. [PMID: 38627264 DOI: 10.1007/s11538-024-01279-z] [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: 11/18/2023] [Accepted: 03/05/2024] [Indexed: 04/19/2024]
Abstract
The microtubule cytoskeleton is responsible for sustained, long-range intracellular transport of mRNAs, proteins, and organelles in neurons. Neuronal microtubules must be stable enough to ensure reliable transport, but they also undergo dynamic instability, as their plus and minus ends continuously switch between growth and shrinking. This process allows for continuous rebuilding of the cytoskeleton and for flexibility in injury settings. Motivated by in vivo experimental data on microtubule behavior in Drosophila neurons, we propose a mathematical model of dendritic microtubule dynamics, with a focus on understanding microtubule length, velocity, and state-duration distributions. We find that limitations on microtubule growth phases are needed for realistic dynamics, but the type of limiting mechanism leads to qualitatively different responses to plausible experimental perturbations. We therefore propose and investigate two minimally-complex length-limiting factors: limitation due to resource (tubulin) constraints and limitation due to catastrophe of large-length microtubules. We combine simulations of a detailed stochastic model with steady-state analysis of a mean-field ordinary differential equations model to map out qualitatively distinct parameter regimes. This provides a basis for predicting changes in microtubule dynamics, tubulin allocation, and the turnover rate of tubulin within microtubules in different experimental environments.
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Affiliation(s)
- Anna C Nelson
- Department of Mathematics, Duke University, Durham, NC, 27710, USA.
| | - Melissa M Rolls
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, PA, 16801, USA
| | - Maria-Veronica Ciocanel
- Department of Mathematics, Duke University, Durham, NC, 27710, USA
- Department of Biology, Duke University, Durham, NC, 27710, USA
| | - Scott A McKinley
- Department of Mathematics, Tulane University, New Orleans, LA, 70118, USA
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3
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Nelson AC, Rolls MM, Ciocanel MV, McKinley SA. Minimal Mechanisms of Microtubule Length Regulation in Living Cells. ARXIV 2024:arXiv:2310.13666v3. [PMID: 37904745 PMCID: PMC10614985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/01/2023]
Abstract
The microtubule cytoskeleton is responsible for sustained, long-range intracellular transport of mRNAs, proteins, and organelles in neurons. Neuronal microtubules must be stable enough to ensure reliable transport, but they also undergo dynamic instability, as their plus and minus ends continuously switch between growth and shrinking. This process allows for continuous rebuilding of the cytoskeleton and for flexibility in injury settings. Motivated by in vivo experimental data on microtubule behavior in Drosophila neurons, we propose a mathematical model of dendritic microtubule dynamics, with a focus on understanding microtubule length, velocity, and state-duration distributions. We find that limitations on microtubule growth phases are needed for realistic dynamics, but the type of limiting mechanism leads to qualitatively different responses to plausible experimental perturbations. We therefore propose and investigate two minimally-complex length-limiting factors: limitation due to resource (tubulin) constraints and limitation due to catastrophe of large-length microtubules. We combine simulations of a detailed stochastic model with steady-state analysis of a mean-field ordinary differential equations model to map out qualitatively distinct parameter regimes. This provides a basis for predicting changes in microtubule dynamics, tubulin allocation, and the turnover rate of tubulin within microtubules in different experimental environments.
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Affiliation(s)
- Anna C Nelson
- Department of Mathematics, Duke University, Durham, 27710, NC, USA
| | - Melissa M Rolls
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, 16801, PA, USA
| | - Maria-Veronica Ciocanel
- Department of Mathematics, Duke University, Durham, 27710, NC, USA
- Department of Biology, Duke University, Durham, 27710, NC, USA
| | - Scott A McKinley
- Department of Mathematics, Tulane University, New Orleans, 70118, LA, USA
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4
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Smart K, Sharp DJ. The fidgetin family: Shaking things up among the microtubule-severing enzymes. Cytoskeleton (Hoboken) 2024; 81:151-166. [PMID: 37823563 DOI: 10.1002/cm.21799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023]
Abstract
The microtubule cytoskeleton is required for several crucial cellular processes, including chromosome segregation, cell polarity and orientation, and intracellular transport. These functions rely on microtubule stability and dynamics, which are regulated by microtubule-binding proteins (MTBPs). One such type of regulator is the microtubule-severing enzymes (MSEs), which are ATPases Associated with Diverse Cellular Activities (AAA+ ATPases). The most recently identified family are the fidgetins, which contain three members: fidgetin, fidgetin-like 1 (FL1), and fidgetin-like 2 (FL2). Of the three known MSE families, the fidgetins have the most diverse range of functions in the cell, spanning mitosis/meiosis, development, cell migration, DNA repair, and neuronal function. Furthermore, they offer intriguing novel therapeutic targets for cancer, cardiovascular disease, and wound healing. In the two decades since their first report, there has been great progress in our understanding of the fidgetins; however, there is still much left unknown about this unusual family. This review aims to consolidate the present body of knowledge of the fidgetin family of MSEs and to inspire deeper exploration into the fidgetins and the MSEs as a whole.
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Affiliation(s)
- Karishma Smart
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - David J Sharp
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA
- Microcures, Inc., Bronx, New York, USA
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5
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Wang J, Sun L, Liu Y, Zhang Y. FIGNL1 Promotes Hepatocellular Carcinoma Formation via Remodeling ECM-receptor Interaction Pathway Mediated by HMMR. Curr Gene Ther 2024; 24:249-263. [PMID: 37929733 PMCID: PMC11071652 DOI: 10.2174/0115665232274223231017052707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 09/02/2023] [Accepted: 09/03/2023] [Indexed: 11/07/2023]
Abstract
BACKGROUND The development of novel biomarkers is crucial for the treatment of HCC. In this study, we investigated a new molecular therapeutic target for HCC. Fidgetin-like 1 (FIGNL1) has been reported to play a vital role in lung adenocarcinoma. However, the potential function of FIGNL1 in HCC is still unknown. OBJECTIVE This study aims to investigate the key regulatory mechanisms of FIGNL1 in the formation of HCC. METHODS The regulatory effect of FIGNL1 on HCC was studied by lentivirus infection. In vitro, the effects of FIGNL1 on the proliferation, migration and apoptosis of cells were investigated by CCK8, colony formation assay, transwell and flow cytometry. Meanwhile, the regulation of FIGNL1 on HCC formation in vivo was studied by subcutaneous transplanted tumors. In addition, using transcriptome sequencing technology, we further explored the specific molecular mechanism of FIGNL1 regulating the formation of HCC. RESULTS Functionally, we demonstrated that FIGNL1 knockdown significantly inhibited HCC cell proliferation, migration and promoted cell apoptosis in vitro. Similarly, the knockdown of FIGNL1 meaningfully weakened hepatocarcinogenesis in nude mice. Transcriptome sequencing revealed that FIGNL1 affected the expression of genes involved in extracellular matrix-receptor (ECM-receptor) interaction pathway, such as hyaluronan mediated motility receptor (HMMR). Further validation found that overexpression of HMMR based on knockdown FIGNL1 can rescue the expression abundance of related genes involved in the ECM-receptor interaction pathway. CONCLUSION Our study revealed that FIGNL1 could modulate the ECM-receptor interaction pathway through the regulation of HMMR, thus regulating the formation of HCC.
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Affiliation(s)
- Jiabei Wang
- Anhui Province Key Laboratory of Hepatopancreatobiliary Surgery, Department of Hepatobiliary Surgery, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, 230001, China
| | - Linmao Sun
- Anhui Province Key Laboratory of Hepatopancreatobiliary Surgery, Department of Hepatobiliary Surgery, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, 230001, China
| | - Yao Liu
- Anhui Province Key Laboratory of Hepatopancreatobiliary Surgery, Department of Hepatobiliary Surgery, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, 230001, China
| | - Yunguang Zhang
- Anhui Province Key Laboratory of Hepatopancreatobiliary Surgery, Department of Hepatobiliary Surgery, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, 230001, China
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6
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Dzaki N, Bu S, Lau SSY, Yong WL, Yu F. Drosophila GSK3β promotes microtubule disassembly and dendrite pruning in sensory neurons. Development 2022; 149:281771. [PMID: 36264221 DOI: 10.1242/dev.200844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 10/06/2022] [Indexed: 11/17/2022]
Abstract
The evolutionarily conserved Glycogen Synthase Kinase 3β (GSK3β), a negative regulator of microtubules, is crucial for neuronal polarization, growth and migration during animal development. However, it remains unknown whether GSK3β regulates neuronal pruning, which is a regressive process. Here, we report that the Drosophila GSK3β homologue Shaggy (Sgg) is cell-autonomously required for dendrite pruning of ddaC sensory neurons during metamorphosis. Sgg is necessary and sufficient to promote microtubule depolymerization, turnover and disassembly in the dendrites. Although Sgg is not required for the minus-end-out microtubule orientation in dendrites, hyperactivated Sgg can disturb the dendritic microtubule orientation. Moreover, our pharmacological and genetic data suggest that Sgg is required to promote dendrite pruning at least partly via microtubule disassembly. We show that Sgg and Par-1 kinases act synergistically to promote microtubule disassembly and dendrite pruning. Thus, Sgg and Par-1 might converge on and phosphorylate a common downstream microtubule-associated protein(s) to disassemble microtubules and thereby facilitate dendrite pruning.
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Affiliation(s)
- Najat Dzaki
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604
| | - Shufeng Bu
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.,Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Samuel Song Yuan Lau
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604
| | - Wei Lin Yong
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.,Department of Biological Sciences, National University of Singapore, Singapore 117543
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7
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Bhattacharjee S, Lottes EN, Nanda S, Golshir A, Patel AA, Ascoli GA, Cox DN. PP2A phosphatase regulates cell-type specific cytoskeletal organization to drive dendrite diversity. Front Mol Neurosci 2022; 15:926567. [PMID: 36452406 PMCID: PMC9702092 DOI: 10.3389/fnmol.2022.926567] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 10/27/2022] [Indexed: 11/15/2022] Open
Abstract
Uncovering molecular mechanisms regulating dendritic diversification is essential to understanding the formation and modulation of functional neural circuitry. Transcription factors play critical roles in promoting dendritic diversity and here, we identify PP2A phosphatase function as a downstream effector of Cut-mediated transcriptional regulation of dendrite development. Mutant analyses of the PP2A catalytic subunit (mts) or the scaffolding subunit (PP2A-29B) reveal cell-type specific regulatory effects with the PP2A complex required to promote dendritic growth and branching in Drosophila Class IV (CIV) multidendritic (md) neurons, whereas in Class I (CI) md neurons, PP2A functions in restricting dendritic arborization. Cytoskeletal analyses reveal requirements for Mts in regulating microtubule stability/polarity and F-actin organization/dynamics. In CIV neurons, mts knockdown leads to reductions in dendritic localization of organelles including mitochondria and satellite Golgi outposts, while CI neurons show increased Golgi outpost trafficking along the dendritic arbor. Further, mts mutant neurons exhibit defects in neuronal polarity/compartmentalization. Finally, genetic interaction analyses suggest β-tubulin subunit 85D is a common PP2A target in CI and CIV neurons, while FoxO is a putative target in CI neurons.
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Affiliation(s)
| | - Erin N. Lottes
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Sumit Nanda
- Center for Neural Informatics, Structures, and Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, United States
| | - Andre Golshir
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Atit A. Patel
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, and Plasticity, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, United States
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
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8
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Kwon JT, Kim Y, Choi S, Yoon BL, Kim HS, Shim I, Sul D. Pulmonary Toxicity and Proteomic Analysis in Bronchoalveolar Lavage Fluids and Lungs of Rats Exposed to Copper Oxide Nanoparticles. Int J Mol Sci 2022; 23:13265. [PMID: 36362054 PMCID: PMC9655042 DOI: 10.3390/ijms232113265] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 10/14/2022] [Accepted: 10/25/2022] [Indexed: 07/21/2023] Open
Abstract
Copper oxide nanoparticles (CuO NPs) were intratracheally instilled into lungs at concentrations of 0, 0.15, and 1.5 mg/kg bodyweight to 7-week-old Sprague-Dawley rats. The cytotoxicity, immunotoxicity, and oxidative stress were evaluated, followed by proteomic analysis of bronchoalveolar lavage fluid (BALF) and lungs of rats. The CuO NPs-exposed groups revealed dose-dependent increases in total cells, polymorphonuclear leukocytes, lactate dyhydrogenase, and total protein levels in BALF. Inflammatory cytokines, including macrophage inflammatory protein-2 and tumor necrosis factor-α, were increased in the CuO NPs-treated groups. The expression levels of catalase, glutathione peroxidase-1, and peroxiredoxin-2 were downregulated, whereas that of superoxide dismutase-2 was upregulated in the CuO NPs-exposed groups. Five heat shock proteins were downregulated in rats exposed to high concentrations of CuO NPs. In proteomic analysis, 17 proteins were upregulated or downregulated, and 6 proteins were validated via Western blot analysis. Significant upregulation of 3-hydroxy-3-methylglutaryl-CoA synthase and fidgetin-like 1 and downregulation of annexin II, HSP 47 and proteasome α1 occurred in the CuO NPs exposed groups. Taken together, this study provides additional insight into pulmonary cytotoxicity and immunotoxicity as well as oxidative stress in rats exposed to CuO NPs. Proteomic analysis revealed potential toxicological biomarkers of CuO NPs, which also reveals the toxicity mechanisms of CuO NPs.
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Affiliation(s)
- Jung-Taek Kwon
- Environmental Health Research Department, National Institute of Environmental Research, Incheon 22689, Korea
| | - Yoonjin Kim
- Environmental Health Research Department, National Institute of Environmental Research, Incheon 22689, Korea
| | - Seonyoung Choi
- Graduate School of Medicine, Korea University, 73 Inchon-ro, Sungbuk-ku, Seoul 136-705, Korea
| | - Byung-ll Yoon
- College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 24341, Korea
| | - Hyun-Sook Kim
- Department of Biomedical Laboratory Science, College of Health Science, Cheongju University, Cheongju 28503, Korea
| | - Ilseob Shim
- Environmental Health Research Department, National Institute of Environmental Research, Incheon 22689, Korea
| | - Donggeun Sul
- Graduate School of Medicine, Korea University, 73 Inchon-ro, Sungbuk-ku, Seoul 136-705, Korea
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9
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Das R, Bhattacharjee S, Letcher JM, Harris JM, Nanda S, Foldi I, Lottes EN, Bobo HM, Grantier BD, Mihály J, Ascoli GA, Cox DN. Formin 3 directs dendritic architecture via microtubule regulation and is required for somatosensory nociceptive behavior. Development 2021; 148:271101. [PMID: 34322714 DOI: 10.1242/dev.187609] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 07/12/2021] [Indexed: 01/26/2023]
Abstract
Dendrite shape impacts functional connectivity and is mediated by organization and dynamics of cytoskeletal fibers. Identifying the molecular factors that regulate dendritic cytoskeletal architecture is therefore important in understanding the mechanistic links between cytoskeletal organization and neuronal function. We identified Formin 3 (Form3) as an essential regulator of cytoskeletal architecture in nociceptive sensory neurons in Drosophila larvae. Time course analyses reveal that Form3 is cell-autonomously required to promote dendritic arbor complexity. We show that form3 is required for the maintenance of a population of stable dendritic microtubules (MTs), and mutants exhibit defects in the localization of dendritic mitochondria, satellite Golgi, and the TRPA channel Painless. Form3 directly interacts with MTs via FH1-FH2 domains. Mutations in human inverted formin 2 (INF2; ortholog of form3) have been causally linked to Charcot-Marie-Tooth (CMT) disease. CMT sensory neuropathies lead to impaired peripheral sensitivity. Defects in form3 function in nociceptive neurons result in severe impairment of noxious heat-evoked behaviors. Expression of the INF2 FH1-FH2 domains partially recovers form3 defects in MTs and nocifensive behavior, suggesting conserved functions, thereby providing putative mechanistic insights into potential etiologies of CMT sensory neuropathies.
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Affiliation(s)
- Ravi Das
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | | | - Jamin M Letcher
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | - Jenna M Harris
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | - Sumit Nanda
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
| | - Istvan Foldi
- Biological Research Centre, Hungarian Academy of Sciences, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Erin N Lottes
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | - Hansley M Bobo
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | | | - József Mihály
- Biological Research Centre, Hungarian Academy of Sciences, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Temesvári krt. 62, Szeged H-6726, Hungary
| | - Giorgio A Ascoli
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
| | - Daniel N Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
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10
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Bu S, Yong WL, Lim BJW, Kondo S, Yu F. A systematic analysis of microtubule-destabilizing factors during dendrite pruning in Drosophila. EMBO Rep 2021; 22:e52679. [PMID: 34338441 DOI: 10.15252/embr.202152679] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 11/09/2022] Open
Abstract
It has long been thought that microtubule disassembly, one of the earliest cellular events, contributes to neuronal pruning and neurodegeneration in development and disease. However, how microtubule disassembly drives neuronal pruning remains poorly understood. Here, we conduct a systematic investigation of various microtubule-destabilizing factors and identify exchange factor for Arf6 (Efa6) and Stathmin (Stai) as new regulators of dendrite pruning in ddaC sensory neurons during Drosophila metamorphosis. We show that Efa6 is both necessary and sufficient to regulate dendrite pruning. Interestingly, Efa6 and Stai facilitate microtubule turnover and disassembly prior to dendrite pruning without compromising the minus-end-out microtubule orientation in dendrites. Moreover, our pharmacological and genetic manipulations strongly support a key role of microtubule disassembly in promoting dendrite pruning. Thus, this systematic study highlights the importance of two selective microtubule destabilizers in dendrite pruning and substantiates a causal link between microtubule disassembly and neuronal pruning.
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Affiliation(s)
- Shufeng Bu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Wei Lin Yong
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Bryan Jian Wei Lim
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shu Kondo
- Invertebrate Genetics Laboratory, National Institute of Genetics, Shizuoka, Japan
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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11
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Clemente V, Hoshino A, Meints J, Shetty M, Starr T, Lee M, Bazzaro M. UNC-45A Is Highly Expressed in the Proliferative Cells of the Mouse Genital Tract and in the Microtubule-Rich Areas of the Mouse Nervous System. Cells 2021; 10:1604. [PMID: 34206743 PMCID: PMC8303485 DOI: 10.3390/cells10071604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 11/16/2022] Open
Abstract
UNC-45A (Protein unc-45 homolog A) is a cytoskeletal-associated protein with a dual and non-mutually exclusive role as a regulator of the actomyosin system and a Microtubule (MT)-destabilizing protein, which is overexpressed in human cancers including in ovarian cancer patients resistant to the MT-stabilizing drug paclitaxel. Mapping of UNC-45A in the mouse upper genital tract and central nervous system reveals its enrichment not only in highly proliferating and prone to remodeling cells, but also in microtubule-rich areas, of the ovaries and the nervous system, respectively. In both apparatuses, UNC-45A is also abundantly expressed in the ciliated epithelium. As regulators of actomyosin contractility and MT stability are essential for the physiopathology of the female reproductive tract and of neuronal development, our findings suggest that UNC-45A may have a role in ovarian cancer initiation and development as well as in neurodegeneration.
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Affiliation(s)
- Valentino Clemente
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, MN 55455, USA; (V.C.); (A.H.); (M.S.); (T.S.)
| | - Asumi Hoshino
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, MN 55455, USA; (V.C.); (A.H.); (M.S.); (T.S.)
| | - Joyce Meints
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA; (J.M.); (M.L.)
| | - Mihir Shetty
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, MN 55455, USA; (V.C.); (A.H.); (M.S.); (T.S.)
| | - Tim Starr
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, MN 55455, USA; (V.C.); (A.H.); (M.S.); (T.S.)
| | - Michael Lee
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA; (J.M.); (M.L.)
| | - Martina Bazzaro
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women’s Health, University of Minnesota, Minneapolis, MN 55455, USA; (V.C.); (A.H.); (M.S.); (T.S.)
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12
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Dong Z, Chen X, Li Y, Zhuo R, Lai X, Liu M. Microtubule Severing Protein Fignl2 Contributes to Endothelial and Neuronal Branching in Zebrafish Development. Front Cell Dev Biol 2021; 8:593234. [PMID: 33585441 PMCID: PMC7873885 DOI: 10.3389/fcell.2020.593234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 12/21/2020] [Indexed: 11/13/2022] Open
Abstract
Previously, fidgetin (fign) and its family members fidgetin-like 1 (fignl1) and fidgetin-like 2 (fignl2) were found to be highly expressed during zebrafish brain development, suggesting their functions in the nervous system. In this study, we report the effects of loss-of-function of these genes on development. We designed and identified single-guide RNAs targeted to generate fign, fignl1, and fignl2 mutants and then observed the overall morphological and behavioral changes. Our findings showed that while fign and fignl1 null mutants displayed no significant defects, fignl2 null zebrafish mutants displayed pericardial edema, reduced heart rate, and smaller eyes; fignl2 null mutants responded to the light-darkness shift with a lower swimming velocity. fignl2 mRNAs were identified in vascular endothelial cells by in situ hybridization and re-analysis of an online dataset of single-cell RNAseq results. Finally, we used morpholino oligonucleotides to confirm that fignl2 knockdown resulted in severe heart edema, which was caused by abnormal vascular branching. The zebrafish fignl2 morphants also showed longer axonal length and more branches of caudal primary neurons. Taken together, we summarize that Fignl2 functions on cellular branches in endothelial cells and neurons. This study reported for the first time that the microtubule-severing protein Fignl2 contributes to cell branching during development.
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Affiliation(s)
- Zhangji Dong
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Xu Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yuanyuan Li
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Run Zhuo
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Xiaona Lai
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Mei Liu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
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13
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Furusawa K, Emoto K. Scrap and Build for Functional Neural Circuits: Spatiotemporal Regulation of Dendrite Degeneration and Regeneration in Neural Development and Disease. Front Cell Neurosci 2021; 14:613320. [PMID: 33505249 PMCID: PMC7829185 DOI: 10.3389/fncel.2020.613320] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/04/2020] [Indexed: 01/01/2023] Open
Abstract
Dendrites are cellular structures essential for the integration of neuronal information. These elegant but complex structures are highly patterned across the nervous system but vary tremendously in their size and fine architecture, each designed to best serve specific computations within their networks. Recent in vivo imaging studies reveal that the development of mature dendrite arbors in many cases involves extensive remodeling achieved through a precisely orchestrated interplay of growth, degeneration, and regeneration of dendritic branches. Both degeneration and regeneration of dendritic branches involve precise spatiotemporal regulation for the proper wiring of functional networks. In particular, dendrite degeneration must be targeted in a compartmentalized manner to avoid neuronal death. Dysregulation of these developmental processes, in particular dendrite degeneration, is associated with certain types of pathology, injury, and aging. In this article, we review recent progress in our understanding of dendrite degeneration and regeneration, focusing on molecular and cellular mechanisms underlying spatiotemporal control of dendrite remodeling in neural development. We further discuss how developmental dendrite degeneration and regeneration are molecularly and functionally related to dendrite remodeling in pathology, disease, and aging.
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Affiliation(s)
- Kotaro Furusawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Kazuo Emoto
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Tokyo, Japan
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14
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Li M, Rui Y, Peng W, Hu J, Jiang A, Yang Z, Huang L. FIGNL1 promotes non‑small cell lung cancer cell proliferation. Int J Oncol 2021; 58:83-99. [PMID: 33367932 PMCID: PMC7721085 DOI: 10.3892/ijo.2020.5154] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 08/31/2020] [Indexed: 12/03/2022] Open
Abstract
Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer‑associated mortality worldwide. In the present study, a novel molecular therapeutic target for lung cancer was investigated. The protein expression level of fidgetin‑like 1 (FIGNL1) in human lung cancer tissues was determined and its potential functions in the H1299 and A549 lung cancer cell lines was subsequently studied. In addition, the protein expression level of FIGNL1 in 109 lung cancer samples and corresponding para‑cancerous tissues was investigated, using immunohistochemical staining. RNA interference and overexpression of FIGNL1 was used to determine the role of FIGNL1 in regulating cell proliferation, and cDNA microarray analysis was performed to identify the potential regulatory pathways. Lastly, the potential role of FIGNL1 in regulating tumorigenesis in lungs and also the proliferation of lung cancer cells was investigated. Firstly, lung cancer tissues were found to express higher protein levels of FIGNL1 and was significantly associated with decreased cell proliferation, migration and invasion abilities, and enhanced cell death. Overexpression of FIGNL1 significantly promoted cell proliferation, including decreased arrest at the G1 phase of the cell cycle and apoptosis, as well as increased ability for fission and migration. These in vitro findings were consistent with the results of the cell‑line derived xenografts in BALB/c nude mice, where tumor growth was decreased when injected with cells transfected with shFIGNL1. Collectively, these results provide suggest that FIGNL1 is involved in cell growth and tumorigenesis.
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Affiliation(s)
- Miao Li
- Department of Respiratory Medicine, Anhui Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021
- Department of General Medicine, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233000
| | - Yan Rui
- Department of Respiration and Critical Care Medicine, Anhui Provincial Key Laboratory of Clinical Basic Research on Respiratory Disease, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004
| | - Wenjia Peng
- Department of Epidemiology and Health Statistics, Bengbu Medical College, Bengbu, Anhui 233030
| | - Junfeng Hu
- Department of Respiration and Critical Care Medicine, Anhui Provincial Key Laboratory of Clinical Basic Research on Respiratory Disease, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004
| | - Anbang Jiang
- Department of Respiration and Critical Care Medicine, Anhui Provincial Key Laboratory of Clinical Basic Research on Respiratory Disease, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004
| | - Zeyu Yang
- Department of Respiration and Critical Care Medicine, Anhui Provincial Key Laboratory of Clinical Basic Research on Respiratory Disease, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004
| | - Linian Huang
- Department of Respiration and Critical Care Medicine, Anhui Provincial Key Laboratory of Clinical Basic Research on Respiratory Disease, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233004
- Department of Respiratory Medicine, Anhui Provincial Hospital, Hefei, Anhui 230000, P.R. China
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15
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Hertzler JI, Simonovitch SI, Albertson RM, Weiner AT, Nye DMR, Rolls MM. Kinetochore proteins suppress neuronal microtubule dynamics and promote dendrite regeneration. Mol Biol Cell 2020; 31:2125-2138. [PMID: 32673176 PMCID: PMC7530905 DOI: 10.1091/mbc.e20-04-0237-t] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Kinetochores connect centromeric chromatin to spindle microtubules during mitosis. Neurons are postmitotic, so it was surprising to identify transcripts of structural kinetochore (KT) proteins and regulatory chromosome passenger complex (CPC) and spindle assembly checkpoint (SAC) proteins in Drosophila neurons after dendrite injury. To test whether these proteins function during dendrite regeneration, postmitotic RNA interference (RNAi) was performed and dendrites or axons were removed using laser microsurgery. Reduction of KT, CPC, and SAC proteins decreased dendrite regeneration without affecting axon regeneration. To understand whether neuronal functions of these proteins rely on microtubules, we analyzed microtubule behavior in uninjured neurons. The number of growing plus, but not minus, ends increased in dendrites with reduced KT, CPC, and SAC proteins, while axonal microtubules were unaffected. Increased dendritic microtubule dynamics was independent of dual leucine zipper kinase (DLK)-mediated stress but was rescued by concurrent reduction of γ-tubulin, the core microtubule nucleation protein. Reduction of γ-tubulin also rescued dendrite regeneration in backgrounds containing kinetochore RNAi transgenes. We conclude that kinetochore proteins function postmitotically in neurons to suppress dendritic microtubule dynamics by inhibiting nucleation.
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Affiliation(s)
- James I Hertzler
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802
| | - Samantha I Simonovitch
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802
| | - Richard M Albertson
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.,MSTP Program, Milton S. Hershey College of Medicine, Hershey, PA 17033
| | - Alexis T Weiner
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802
| | - Derek M R Nye
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.,MSTP Program, Milton S. Hershey College of Medicine, Hershey, PA 17033
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802
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16
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Rolls MM, Thyagarajan P, Feng C. Microtubule dynamics in healthy and injured neurons. Dev Neurobiol 2020; 81:321-332. [PMID: 32291942 DOI: 10.1002/dneu.22746] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/22/2020] [Accepted: 04/08/2020] [Indexed: 12/28/2022]
Abstract
Most neurons must last a lifetime and their microtubule cytoskeleton is an important contributor to their longevity. Neurons have some of the most stable microtubules of all cells, but the tip of every microtubule remains dynamic and, although requiring constant GTP consumption, microtubules are always being rebuilt. While some ongoing level of rebuilding always occurs, overall microtubule stability can be modulated in response to injury and stress as well as the normal developmental process of pruning. Specific microtubule severing proteins act in different contexts to increase microtubule dynamicity and promote degeneration and pruning. After axon injury, complex changes in dynamics occur and these are important for both neuroprotection induced by injury and subsequent outgrowth of a new axon. Understanding how microtubule dynamics is modulated in different scenarios, as well as the impact of the changes in stability, is an important avenue to explore for development of strategies to promote neuroprotection and regeneration.
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Affiliation(s)
- Melissa M Rolls
- Biochemistry and Molecular Biology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Pankajam Thyagarajan
- Biochemistry and Molecular Biology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Chengye Feng
- Biochemistry and Molecular Biology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
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17
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Tang Q, Rui M, Bu S, Wang Y, Chew LY, Yu F. A microtubule polymerase is required for microtubule orientation and dendrite pruning in Drosophila. EMBO J 2020; 39:e103549. [PMID: 32267553 DOI: 10.15252/embj.2019103549] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 01/12/2023] Open
Abstract
Drosophila class IV ddaC neurons selectively prune all larval dendrites to refine the nervous system during metamorphosis. During dendrite pruning, severing of proximal dendrites is preceded by local microtubule (MT) disassembly. Here, we identify an unexpected role of Mini spindles (Msps), a conserved MT polymerase, in governing dendrite pruning. Msps associates with another MT-associated protein TACC, and both stabilize each other in ddaC neurons. Moreover, Msps and TACC are required to orient minus-end-out MTs in dendrites. We further show that the functions of msps in dendritic MT orientation and dendrite pruning are antagonized by the kinesin-13 MT depolymerase Klp10A. Excessive MT depolymerization, which is induced by pharmacological treatment and katanin overexpression, also perturbs dendritic MT orientation and dendrite pruning, phenocopying msps mutants. Thus, we demonstrate that the MT polymerase Msps is required to form dendritic minus-end-out MTs and thereby promotes dendrite pruning in Drosophila sensory neurons.
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Affiliation(s)
- Quan Tang
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore
| | - Menglong Rui
- Temasek Life Sciences Laboratory, Singapore City, Singapore
| | - Shufeng Bu
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore
| | - Yan Wang
- Temasek Life Sciences Laboratory, Singapore City, Singapore
| | - Liang Yuh Chew
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, Singapore City, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore City, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, Singapore City, Singapore.,Neuroscience and Behavioral Disorder Program, Duke-NUS Graduate Medical School Singapore, Singapore City, Singapore
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18
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Hu C, Kanellopoulos AK, Richter M, Petersen M, Konietzny A, Tenedini FM, Hoyer N, Cheng L, Poon CLC, Harvey KF, Windhorst S, Parrish JZ, Mikhaylova M, Bagni C, Calderon de Anda F, Soba P. Conserved Tao Kinase Activity Regulates Dendritic Arborization, Cytoskeletal Dynamics, and Sensory Function in Drosophila. J Neurosci 2020; 40:1819-1833. [PMID: 31964717 PMCID: PMC7046460 DOI: 10.1523/jneurosci.1846-19.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 12/11/2022] Open
Abstract
Dendritic arborization is highly regulated and requires tight control of dendritic growth, branching, cytoskeletal dynamics, and ion channel expression to ensure proper function. Abnormal dendritic development can result in altered network connectivity, which has been linked to neurodevelopmental disorders, including autism spectrum disorders (ASDs). How neuronal growth control programs tune dendritic arborization to ensure function is still not fully understood. Using Drosophila dendritic arborization (da) neurons as a model, we identified the conserved Ste20-like kinase Tao as a negative regulator of dendritic arborization. We show that Tao kinase activity regulates cytoskeletal dynamics and sensory channel localization required for proper sensory function in both male and female flies. We further provide evidence for functional conservation of Tao kinase, showing that its ASD-linked human ortholog, Tao kinase 2 (Taok2), could replace Drosophila Tao and rescue dendritic branching, dynamic microtubule alterations, and behavioral defects. However, several ASD-linked Taok2 variants displayed impaired rescue activity, suggesting that Tao/Taok2 mutations can disrupt sensory neuron development and function. Consistently, we show that Tao kinase activity is required in developing and as well as adult stages for maintaining normal dendritic arborization and sensory function to regulate escape and social behavior. Our data suggest an important role for Tao kinase signaling in cytoskeletal organization to maintain proper dendritic arborization and sensory function, providing a strong link between developmental sensory aberrations and behavioral abnormalities relevant for Taok2-dependent ASDs.SIGNIFICANCE STATEMENT Autism spectrum disorders (ASDs) are linked to abnormal dendritic arbors. However, the mechanisms of how dendritic arbors develop to promote functional and proper behavior are unclear. We identified Drosophila Tao kinase, the ortholog of the ASD risk gene Taok2, as a regulator of dendritic arborization in sensory neurons. We show that Tao kinase regulates cytoskeletal dynamics, controls sensory ion channel localization, and is required to maintain somatosensory function in vivo Interestingly, ASD-linked human Taok2 mutations rendered it nonfunctional, whereas its WT form could restore neuronal morphology and function in Drosophila lacking endogenous Tao. Our findings provide evidence for a conserved role of Tao kinase in dendritic development and function of sensory neurons, suggesting that aberrant sensory function might be a common feature of ASDs.
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Affiliation(s)
- Chun Hu
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | | | - Melanie Richter
- Neuronal Development Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Meike Petersen
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Anja Konietzny
- Neuronal Protein Transport Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Federico M Tenedini
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Nina Hoyer
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Lin Cheng
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Carole L C Poon
- Peter MacCallum Cancer Centre, Melbourne, 3000 Victoria, Australia
| | - Kieran F Harvey
- Peter MacCallum Cancer Centre, Melbourne, 3000 Victoria, Australia
- Department of Anatomy and Developmental Biology, and Biomedicine Discovery Institute, Monash University, Clayton, 3800 Victoria, Australia
| | - Sabine Windhorst
- Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, 98195 Washington, and
| | - Marina Mikhaylova
- Neuronal Protein Transport Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Claudia Bagni
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Froylan Calderon de Anda
- Neuronal Development Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Peter Soba
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany,
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19
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Vargas EJM, Matamoros AJ, Qiu J, Jan CH, Wang Q, Gorczyca D, Han TW, Weissman JS, Jan YN, Banerjee S, Song Y. The microtubule regulator ringer functions downstream from the RNA repair/splicing pathway to promote axon regeneration. Genes Dev 2020; 34:194-208. [PMID: 31919191 PMCID: PMC7000917 DOI: 10.1101/gad.331330.119] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/10/2019] [Indexed: 12/17/2022]
Abstract
In this study, Vargas et al. set out to elucidate the downstream effectors of the Rtca-mediated RNA repair/splicing pathway. Using genome-wide transcriptome analysis, the authors demonstrate that the microtubule-associated protein (MAP) tubulin polymerization-promoting protein (TPPP) ringer functions downstream from and is suppressed by Rtca via Xbp1-dependent transcription. Ringer cell-autonomously promotes axon regeneration in the peripheral and central nervous system. Promoting axon regeneration in the central and peripheral nervous system is of clinical importance in neural injury and neurodegenerative diseases. Both pro- and antiregeneration factors are being identified. We previously reported that the Rtca mediated RNA repair/splicing pathway restricts axon regeneration by inhibiting the nonconventional splicing of Xbp1 mRNA under cellular stress. However, the downstream effectors remain unknown. Here, through transcriptome profiling, we show that the tubulin polymerization-promoting protein (TPPP) ringmaker/ringer is dramatically increased in Rtca-deficient Drosophila sensory neurons, which is dependent on Xbp1. Ringer is expressed in sensory neurons before and after injury, and is cell-autonomously required for axon regeneration. While loss of ringer abolishes the regeneration enhancement in Rtca mutants, its overexpression is sufficient to promote regeneration both in the peripheral and central nervous system. Ringer maintains microtubule stability/dynamics with the microtubule-associated protein futsch/MAP1B, which is also required for axon regeneration. Furthermore, ringer lies downstream from and is negatively regulated by the microtubule-associated deacetylase HDAC6, which functions as a regeneration inhibitor. Taken together, our findings suggest that ringer acts as a hub for microtubule regulators that relays cellular status information, such as cellular stress, to the integrity of microtubules in order to instruct neuroregeneration.
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Affiliation(s)
- Ernest J Monahan Vargas
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Andrew J Matamoros
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jingyun Qiu
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Calvin H Jan
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94158, USA.,Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA
| | - Qin Wang
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - David Gorczyca
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Tina W Han
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94158, USA.,Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Swati Banerjee
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health Science Center, San Antonio, Texas 78229, USA
| | - Yuanquan Song
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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20
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Hahn I, Voelzmann A, Liew YT, Costa-Gomes B, Prokop A. The model of local axon homeostasis - explaining the role and regulation of microtubule bundles in axon maintenance and pathology. Neural Dev 2019; 14:11. [PMID: 31706327 PMCID: PMC6842214 DOI: 10.1186/s13064-019-0134-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 10/02/2019] [Indexed: 12/20/2022] Open
Abstract
Axons are the slender, cable-like, up to meter-long projections of neurons that electrically wire our brains and bodies. In spite of their challenging morphology, they usually need to be maintained for an organism's lifetime. This makes them key lesion sites in pathological processes of ageing, injury and neurodegeneration. The morphology and physiology of axons crucially depends on the parallel bundles of microtubules (MTs), running all along to serve as their structural backbones and highways for life-sustaining cargo transport and organelle dynamics. Understanding how these bundles are formed and then maintained will provide important explanations for axon biology and pathology. Currently, much is known about MTs and the proteins that bind and regulate them, but very little about how these factors functionally integrate to regulate axon biology. As an attempt to bridge between molecular mechanisms and their cellular relevance, we explain here the model of local axon homeostasis, based on our own experiments in Drosophila and published data primarily from vertebrates/mammals as well as C. elegans. The model proposes that (1) the physical forces imposed by motor protein-driven transport and dynamics in the confined axonal space, are a life-sustaining necessity, but pose a strong bias for MT bundles to become disorganised. (2) To counterbalance this risk, MT-binding and -regulating proteins of different classes work together to maintain and protect MT bundles as necessary transport highways. Loss of balance between these two fundamental processes can explain the development of axonopathies, in particular those linking to MT-regulating proteins, motors and transport defects. With this perspective in mind, we hope that more researchers incorporate MTs into their work, thus enhancing our chances of deciphering the complex regulatory networks that underpin axon biology and pathology.
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Affiliation(s)
- Ines Hahn
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - André Voelzmann
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - Yu-Ting Liew
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - Beatriz Costa-Gomes
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK.
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21
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Feng C, Thyagarajan P, Shorey M, Seebold DY, Weiner AT, Albertson RM, Rao KS, Sagasti A, Goetschius DJ, Rolls MM. Patronin-mediated minus end growth is required for dendritic microtubule polarity. J Cell Biol 2019; 218:2309-2328. [PMID: 31076454 PMCID: PMC6605808 DOI: 10.1083/jcb.201810155] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 03/13/2019] [Accepted: 04/23/2019] [Indexed: 02/06/2023] Open
Abstract
Feng et al. describe persistent neuronal microtubule minus end growth that depends on the CAMSAP protein Patronin and is needed for dendritic minus-end-out polarity. Microtubule minus ends are thought to be stable in cells. Surprisingly, in Drosophila and zebrafish neurons, we observed persistent minus end growth, with runs lasting over 10 min. In Drosophila, extended minus end growth depended on Patronin, and Patronin reduction disrupted dendritic minus-end-out polarity. In fly dendrites, microtubule nucleation sites localize at dendrite branch points. Therefore, we hypothesized minus end growth might be particularly important beyond branch points. Distal dendrites have mixed polarity, and reduction of Patronin lowered the number of minus-end-out microtubules. More strikingly, extra Patronin made terminal dendrites almost completely minus-end-out, indicating low Patronin normally limits minus-end-out microtubules. To determine whether minus end growth populated new dendrites with microtubules, we analyzed dendrite development and regeneration. Minus ends extended into growing dendrites in the presence of Patronin. In sum, our data suggest that Patronin facilitates sustained microtubule minus end growth, which is critical for populating dendrites with minus-end-out microtubules.
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Affiliation(s)
- Chengye Feng
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Pankajam Thyagarajan
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Matthew Shorey
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Dylan Y Seebold
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Alexis T Weiner
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Richard M Albertson
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Kavitha S Rao
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Alvaro Sagasti
- Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA
| | - Daniel J Goetschius
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA
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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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Kounakis K, Tavernarakis N. The Cytoskeleton as a Modulator of Aging and Neurodegeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1178:227-245. [PMID: 31493230 DOI: 10.1007/978-3-030-25650-0_12] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The cytoskeleton consists of filamentous protein polymers that form organized structures, contributing to a multitude of cell life aspects. It includes three types of polymers: the actin microfilaments, the microtubules and the intermediate filaments. Decades of research have implicated the cytoskeleton in processes that regulate cellular and organismal aging, as well as neurodegeneration associated with injury or neurodegenerative disease, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic Lateral Sclerosis, or Charcot Marie Tooth disease. Here, we provide a brief overview of cytoskeletal structure and function, and discuss experimental evidence linking cytoskeletal function and dynamics with aging and neurodegeneration.
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Affiliation(s)
- Konstantinos Kounakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece.,Department of Basic Sciences, Medical School, University of Crete, Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece. .,Department of Basic Sciences, Medical School, University of Crete, Heraklion, Greece.
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24
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McNally FJ, Roll-Mecak A. Microtubule-severing enzymes: From cellular functions to molecular mechanism. J Cell Biol 2018; 217:4057-4069. [PMID: 30373906 PMCID: PMC6279391 DOI: 10.1083/jcb.201612104] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/13/2018] [Accepted: 10/04/2018] [Indexed: 12/24/2022] Open
Abstract
McNally and Roll-Mecak review the molecular mechanism of microtubule-severing enzymes and their diverse roles in processes ranging from cell division to ciliogensis and morphogenesis. Microtubule-severing enzymes generate internal breaks in microtubules. They are conserved in eukaryotes from ciliates to mammals, and their function is important in diverse cellular processes ranging from cilia biogenesis to cell division, phototropism, and neurogenesis. Their mutation leads to neurodegenerative and neurodevelopmental disorders in humans. All three known microtubule-severing enzymes, katanin, spastin, and fidgetin, are members of the meiotic subfamily of AAA ATPases that also includes VPS4, which disassembles ESCRTIII polymers. Despite their conservation and importance to cell physiology, the cellular and molecular mechanisms of action of microtubule-severing enzymes are not well understood. Here we review a subset of cellular processes that require microtubule-severing enzymes as well as recent advances in understanding their structure, biophysical mechanism, and regulation.
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Affiliation(s)
- Francis J McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD .,Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD
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25
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Identification of Proteins Required for Precise Positioning of Apc2 in Dendrites. G3-GENES GENOMES GENETICS 2018; 8:1841-1853. [PMID: 29602811 PMCID: PMC5940173 DOI: 10.1534/g3.118.200205] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In Drosophila neurons, uniform minus-end-out polarity in dendrites is maintained in part by kinesin-2-mediated steering of growing microtubules at branch points. Apc links the kinesin motor to growing microtubule plus ends and Apc2 recruits Apc to branch points where it functions. Because Apc2 acts to concentrate other steering proteins to branch points, we wished to understand how Apc2 is targeted. From an initial broad candidate RNAi screen, we found Miro (a mitochondrial transport protein), Ank2, Axin, spastin and Rac1 were required to position Apc2-GFP at dendrite branch points. YFP-Ank2-L8, Axin-GFP and mitochondria also localized to branch points suggesting the screen identified relevant proteins. By performing secondary screens, we found that energy production by mitochondria was key for Apc2-GFP positioning and spastin acted upstream of mitochondria. Ank2 seems to act independently from other players, except its membrane partner, Neuroglian (Nrg). Rac1 likely acts through Arp2/3 to generate branched actin to help recruit Apc2-GFP. Axin can function in a variety of wnt signaling pathways, one of which includes heterotrimeric G proteins and Frizzleds. Knockdown of Gαs, Gαo, Fz and Fz2, reduced targeting of Apc2 and Axin to branch points. Overall our data suggest that mitochondrial energy production, Nrg/Ank2, branched actin generated by Arp2/3 and Fz/G proteins/Axin function as four modules that control localization of the microtubule regulator Apc2 to its site of action in dendrite branch points.
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26
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Alp M, Cucinotta FA. Biophysics Model of Heavy-Ion Degradation of Neuron Morphology in Mouse Hippocampal Granular Cell Layer Neurons. Radiat Res 2018; 189:312-325. [PMID: 29502499 PMCID: PMC5872156 DOI: 10.1667/rr14923.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Exposure to heavy-ion radiation during cancer treatment or space travel may cause cognitive detriments that have been associated with changes in neuron morphology and plasticity. Observations in mice of reduced neuronal dendritic complexity have revealed a dependence on radiation quality and absorbed dose, suggesting that microscopic energy deposition plays an important role. In this work we used morphological data for mouse dentate granular cell layer (GCL) neurons and a stochastic model of particle track structure and microscopic energy deposition (ED) to develop a predictive model of high-charge and energy (HZE) particle-induced morphological changes to the complex structures of dendritic arbors. We represented dendrites as cylindrical segments of varying diameter with unit aspect ratios, and developed a fast sampling method to consider the stochastic distribution of ED by δ rays (secondary electrons) around the path of heavy ions, to reduce computational times. We introduce probabilistic models with a small number of parameters to describe the induction of precursor lesions that precede dendritic snipping, denoted as snip sites. Predictions for oxygen (16O, 600 MeV/n) and titanium (48Ti, 600 MeV/n) particles with LET of 16.3 and 129 keV/μm, respectively, are considered. Morphometric parameters to quantify changes in neuron morphology are described, including reduction in total dendritic length, number of branch points and branch numbers. Sholl analysis is applied for single neurons to elucidate dose-dependent reductions in dendritic complexity. We predict important differences in measurements from imaging of tissues from brain slices with single neuron cell observations due to the role of neuron death through both soma apoptosis and excessive dendritic length reduction. To further elucidate the role of track structure, random segment excision (snips) models are introduced and a sensitivity study of the effects of the modes of neuron death in predictions of morphometric parameters is described. An important conclusion of this study is that δ rays play a major role in neuron morphological changes due to the large spatial distribution of damage sites, which results in a reduced dependence on LET, including modest difference between 16O and 48Ti, compared to damages resulting from ED in localized damage sites.
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Affiliation(s)
- Murat Alp
- Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada
| | - Francis A. Cucinotta
- Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada
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27
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Hao Y, Collins C. Intrinsic mechanisms for axon regeneration: insights from injured axons in Drosophila. Curr Opin Genet Dev 2017; 44:84-91. [PMID: 28232273 PMCID: PMC5447494 DOI: 10.1016/j.gde.2017.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/17/2017] [Accepted: 01/26/2017] [Indexed: 12/18/2022]
Abstract
Axonal damage and loss are common and negative consequences of neuronal injuries, and also occur in some neurodegenerative diseases. For neurons to have a chance to repair their connections, they need to survive the damage, initiate new axonal growth, and ultimately establish new synaptic connections. This review discusses how recent work in Drosophila models have informed our understanding of the cellular pathways used by neurons to respond to axonal injuries. Similarly to mammalian neurons, Drosophila neurons appear to be more limited in their capacity regrow (regenerate) damaged axons in the central nervous system, but can undergo axonal regeneration to varying extents in the peripheral nervous system. Conserved cellular pathways are activated by axonal injury via mechanisms that are specific to axons but not dendrites, and new unanticipated inhibitors of axon regeneration can be identified via genetic screening. These findings, made predominantly via genetic and live imaging methods in Drosophila, emphasize the utility of this model organism for the identification and study of basic cellular mechanisms used for neuronal repair.
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Affiliation(s)
- Yan Hao
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Catherine Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
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28
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Herzmann S, Krumkamp R, Rode S, Kintrup C, Rumpf S. PAR-1 promotes microtubule breakdown during dendrite pruning in Drosophila. EMBO J 2017; 36:1981-1991. [PMID: 28554895 DOI: 10.15252/embj.201695890] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 04/21/2017] [Accepted: 04/26/2017] [Indexed: 11/09/2022] Open
Abstract
Pruning of unspecific neurites is an important mechanism during neuronal morphogenesis. Drosophila sensory neurons prune their dendrites during metamorphosis. Pruning dendrites are severed in their proximal regions. Prior to severing, dendritic microtubules undergo local disassembly, and dendrites thin extensively through local endocytosis. Microtubule disassembly requires a katanin homologue, but the signals initiating microtubule breakdown are not known. Here, we show that the kinase PAR-1 is required for pruning and dendritic microtubule breakdown. Our data show that neurons lacking PAR-1 fail to break down dendritic microtubules, and PAR-1 is required for an increase in neuronal microtubule dynamics at the onset of metamorphosis. Mammalian PAR-1 is a known Tau kinase, and genetic interactions suggest that PAR-1 promotes microtubule breakdown largely via inhibition of Tau also in Drosophila Finally, PAR-1 is also required for dendritic thinning, suggesting that microtubule breakdown might precede ensuing plasma membrane alterations. Our results shed light on the signaling cascades and epistatic relationships involved in neurite destabilization during dendrite pruning.
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Affiliation(s)
- Svende Herzmann
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Rafael Krumkamp
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Sandra Rode
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Carina Kintrup
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Sebastian Rumpf
- Institute for Neurobiology, University of Münster, Münster, Germany
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29
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Oren-Suissa M, Gattegno T, Kravtsov V, Podbilewicz B. Extrinsic Repair of Injured Dendrites as a Paradigm for Regeneration by Fusion in Caenorhabditis elegans. Genetics 2017; 206:215-230. [PMID: 28283540 PMCID: PMC5419471 DOI: 10.1534/genetics.116.196386] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 03/07/2017] [Indexed: 11/18/2022] Open
Abstract
Injury triggers regeneration of axons and dendrites. Research has identified factors required for axonal regeneration outside the CNS, but little is known about regeneration triggered by dendrotomy. Here, we study neuronal plasticity triggered by dendrotomy and determine the fate of complex PVD arbors following laser surgery of dendrites. We find that severed primary dendrites grow toward each other and reconnect via branch fusion. Simultaneously, terminal branches lose self-avoidance and grow toward each other, meeting and fusing at the tips via an AFF-1-mediated process. Ectopic branch growth is identified as a step in the regeneration process required for bypassing the lesion site. Failure of reconnection to the severed dendrites results in degeneration of the distal end of the neuron. We discover pruning of excess branches via EFF-1 that acts to recover the original wild-type arborization pattern in a late stage of the process. In contrast, AFF-1 activity during dendritic auto-fusion is derived from the lateral seam cells and not autonomously from the PVD neuron. We propose a model in which AFF-1-vesicles derived from the epidermal seam cells fuse neuronal dendrites. Thus, EFF-1 and AFF-1 fusion proteins emerge as new players in neuronal arborization and maintenance of arbor connectivity following injury in Caenorhabditis elegans Our results demonstrate that there is a genetically determined multi-step pathway to repair broken dendrites in which EFF-1 and AFF-1 act on different steps of the pathway. EFF-1 is essential for dendritic pruning after injury and extrinsic AFF-1 mediates dendrite fusion to bypass injuries.
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Affiliation(s)
- Meital Oren-Suissa
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Tamar Gattegno
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Veronika Kravtsov
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Benjamin Podbilewicz
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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