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Schmitt C, Mauker P, Vepřek NA, Gierse C, Meiring JCM, Kuch J, Akhmanova A, Dehmelt L, Thorn-Seshold O. A Photocaged Microtubule-Stabilising Epothilone Allows Spatiotemporal Control of Cytoskeletal Dynamics. Angew Chem Int Ed Engl 2024; 63:e202410169. [PMID: 38961560 DOI: 10.1002/anie.202410169] [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: 05/29/2024] [Revised: 06/28/2024] [Accepted: 07/03/2024] [Indexed: 07/05/2024]
Abstract
The cytoskeleton is essential for spatial and temporal organisation of a wide range of cellular and tissue-level processes, such as proliferation, signalling, cargo transport, migration, morphogenesis, and neuronal development. Cytoskeleton research aims to study these processes by imaging, or by locally manipulating, the dynamics and organisation of cytoskeletal proteins with high spatiotemporal resolution: which matches the capabilities of optical methods. To date, no photoresponsive microtubule-stabilising tool has united all the features needed for a practical high-precision reagent: a low potency and biochemically stable non-illuminated state; then an efficient, rapid, and clean photoresponse that generates a high potency illuminated state; plus good solubility at suitable working concentrations; and efficient synthetic access. We now present CouEpo, a photocaged epothilone microtubule-stabilising reagent that combines these needs. Its potency increases approximately 100-fold upon irradiation by violet/blue light to reach low-nanomolar values, allowing efficient photocontrol of microtubule dynamics in live cells, and even the generation of cellular asymmetries in microtubule architecture and cell dynamics. CouEpo is thus a high-performance tool compound that can support high-precision research into many microtubule-associated processes, from biophysics to transport, cell motility, and neuronal physiology.
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Affiliation(s)
- Carina Schmitt
- Department of Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstrasse 7, Munich, 81377, Germany
| | - Philipp Mauker
- Department of Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstrasse 7, Munich, 81377, Germany
| | - Nynke A Vepřek
- Department of Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstrasse 7, Munich, 81377, Germany
| | - Carolin Gierse
- Department of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Str. 4a, Dortmund, 44227, Germany
| | - Joyce C M Meiring
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | - Jürgen Kuch
- Department of Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstrasse 7, Munich, 81377, Germany
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | - Leif Dehmelt
- Department of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Str. 4a, Dortmund, 44227, Germany
| | - Oliver Thorn-Seshold
- Department of Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstrasse 7, Munich, 81377, Germany
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2
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Dey S, Kumar N, Balakrishnan S, Koushika SP, Ghosh-Roy A. KLP-7/Kinesin-13 orchestrates axon-dendrite checkpoints for polarized trafficking in neurons. Mol Biol Cell 2024; 35:ar115. [PMID: 38985513 PMCID: PMC7616348 DOI: 10.1091/mbc.e23-08-0335] [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: 09/05/2023] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/12/2024] Open
Abstract
The polarized nature of neurons depends on their microtubule dynamics and orientation determined by both microtubule-stabilizing and destabilizing factors. The role of destabilizing factors in developing and maintaining neuronal polarity is unclear. We investigated the function of KLP-7, a microtubule depolymerizing motor of the Kinesin-13 family, in axon-dendrite compartmentalization using PVD neurons in Caenorhabditis elegans. Loss of KLP-7 caused a mislocalization of axonal proteins, including RAB-3, SAD-1, and their motor UNC-104, to dendrites. This is rescued by cell-autonomous expression of the KLP-7 or colchicine treatment, indicating the involvement of KLP-7-dependent microtubule depolymerization. The high mobility of KLP-7 is correlated to increased microtubule dynamics in the dendrites, which restricts the enrichment of UNC-44, an integral component of Axon Initial Segment (AIS) in these processes. Due to the loss of KLP-7, ectopic enrichment of UNC-44 in the dendrite potentially redirects axonal traffic into dendrites that include plus-end out microtubules, axonal motors, and cargoes. These observations indicate that KLP-7-mediated depolymerization defines the microtubule dynamics conducive to the specific enrichment of AIS components in dendrites. This further compartmentalizes dendritic and axonal microtubules, motors, and cargoes, thereby influencing neuronal polarity.
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Affiliation(s)
- Swagata Dey
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
| | - Nitish Kumar
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
| | - Supraja Balakrishnan
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
| | - Sandhya P. Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Anindya Ghosh-Roy
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
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3
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Nanda S, Calderon A, Sachan A, Duong TT, Koch J, Xin X, Solouk-Stahlberg D, Wu YW, Nalbant P, Dehmelt L. Rho GTPase activity crosstalk mediated by Arhgef11 and Arhgef12 coordinates cell protrusion-retraction cycles. Nat Commun 2023; 14:8356. [PMID: 38102112 PMCID: PMC10724141 DOI: 10.1038/s41467-023-43875-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 11/22/2023] [Indexed: 12/17/2023] Open
Abstract
Rho GTPases play a key role in the spatio-temporal coordination of cytoskeletal dynamics during cell migration. Here, we directly investigate crosstalk between the major Rho GTPases Rho, Rac and Cdc42 by combining rapid activity perturbation with activity measurements in mammalian cells. These studies reveal that Rac stimulates Rho activity. Direct measurement of spatio-temporal activity patterns show that Rac activity is tightly and precisely coupled to local cell protrusions, followed by Rho activation during retraction. Furthermore, we find that the Rho-activating Lbc-type GEFs Arhgef11 and Arhgef12 are enriched at transient cell protrusions and retractions and recruited to the plasma membrane by active Rac. In addition, their depletion reduces activity crosstalk, cell protrusion-retraction dynamics and migration distance and increases migration directionality. Thus, our study shows that Arhgef11 and Arhgef12 facilitate exploratory cell migration by coordinating cell protrusion and retraction by coupling the activity of the associated regulators Rac and Rho.
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Affiliation(s)
- Suchet Nanda
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Abram Calderon
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Arya Sachan
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
| | - Thanh-Thuy Duong
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Johannes Koch
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, 45141, Essen, Germany
| | - Xiaoyi Xin
- SciLifeLab and Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, 90187, Umeå, Sweden
| | - Djamschid Solouk-Stahlberg
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Yao-Wen Wu
- SciLifeLab and Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, 90187, Umeå, Sweden
| | - Perihan Nalbant
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, 45141, Essen, Germany.
| | - Leif Dehmelt
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany.
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4
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Bennison SA, Blazejewski SM, Liu X, Hacohen-Kleiman G, Sragovich S, Zoidou S, Touloumi O, Grigoriadis N, Gozes I, Toyo-Oka K. The cytoplasmic localization of ADNP through 14-3-3 promotes sex-dependent neuronal morphogenesis, cortical connectivity, and calcium signaling. Mol Psychiatry 2023; 28:1946-1959. [PMID: 36631597 DOI: 10.1038/s41380-022-01939-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 12/13/2022] [Accepted: 12/22/2022] [Indexed: 01/13/2023]
Abstract
Defective neuritogenesis is a contributing pathogenic mechanism underlying a variety of neurodevelopmental disorders. Single gene mutations in activity-dependent neuroprotective protein (ADNP) are the most frequent among autism spectrum disorders (ASDs) leading to the ADNP syndrome. Previous studies showed that during neuritogenesis, Adnp localizes to the cytoplasm/neurites, and Adnp knockdown inhibits neuritogenesis in culture. Here, we hypothesized that Adnp is localized in the cytoplasm during neurite formation and that this process is mediated by 14-3-3. Indeed, applying the 14-3-3 inhibitor, difopein, blocked Adnp cytoplasmic localization. Furthermore, co-immunoprecipitations showed that Adnp bound 14-3-3 proteins and proteomic analysis identified several potential phosphorylation-dependent Adnp/14-3-3 binding sites. We further discovered that knockdown of Adnp using in utero electroporation of mouse layer 2/3 pyramidal neurons in the somatosensory cortex led to previously unreported changes in neurite formation beginning at P0. Defects were sustained throughout development, the most notable included increased basal dendrite number and axon length. Paralleling the observed morphological aberrations, ex vivo calcium imaging revealed that Adnp deficient neurons had greater and more frequent spontaneous calcium influx in female mice. GRAPHIC, a novel synaptic tracing technology substantiated this finding, revealing increased interhemispheric connectivity between female Adnp deficient layer 2/3 pyramidal neurons. We conclude that Adnp is localized to the cytoplasm by 14-3-3 proteins, where it regulates neurite formation, maturation, and functional cortical connectivity significantly building on our current understanding of Adnp function and the etiology of ADNP syndrome.
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Affiliation(s)
- Sarah A Bennison
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Sara M Blazejewski
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Xiaonan Liu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA
| | - Gal Hacohen-Kleiman
- The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Shlomo Sragovich
- The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Sofia Zoidou
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Olga Touloumi
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Nikolaos Grigoriadis
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Illana Gozes
- The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Kazuhito Toyo-Oka
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA.
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5
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Bennison SA, Liu X, Toyo-Oka K. Nuak kinase signaling in development and disease of the central nervous system. Cell Signal 2022; 100:110472. [PMID: 36122883 DOI: 10.1016/j.cellsig.2022.110472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/11/2022] [Accepted: 09/13/2022] [Indexed: 01/14/2023]
Abstract
Protein kinases represent important signaling hubs for a variety of biological functions. Many kinases are traditionally studied for their roles in cancer cell biology, but recent advances in neuroscience research show repurposed kinase function to be important for nervous system development and function. Two members of the AMP-activated protein kinase (AMPK) related family, NUAK1 and NUAK2, have drawn attention in neuroscience due to their mutations in autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia, and intellectual disability (ID). Furthermore, Nuak kinases have also been implicated in tauopathy and other disorders of aging. This review highlights what is known about the Nuak kinases in nervous system development and disease and explores the possibility of Nuak kinases as targets for therapeutic innovation.
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Affiliation(s)
- Sarah A Bennison
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Xiaonan Liu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | - Kazuhito Toyo-Oka
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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6
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Powers RM, Daza R, Koehler AE, Courchet J, Calabrese B, Hevner RF, Halpain S. Growth cone macropinocytosis of neurotrophin receptor and neuritogenesis are regulated by neuron navigator 1. Mol Biol Cell 2022; 33:ar64. [PMID: 35352947 PMCID: PMC9561856 DOI: 10.1091/mbc.e21-12-0623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neuron navigator 1 (Nav1) is a cytoskeleton-associated protein expressed during brain development that is necessary for proper neuritogenesis, but the underlying mechanisms are poorly understood. Here we show that Nav1 is present in elongating axon tracts during mouse brain embryogenesis. We found that depletion of Nav1 in cultured neurons disrupts growth cone morphology and neurotrophin-stimulated neuritogenesis. In addition to regulating both F-actin and microtubule properties, Nav1 promotes actin-rich membrane ruffles in the growth cone and promotes macropinocytosis at those membrane ruffles, including internalization of the TrkB receptor for the neurotrophin brain-derived neurotropic factor (BDNF). Growth cone macropinocytosis is important for downstream signaling, neurite targeting, and membrane recycling, implicating Nav1 in one or more of these processes. Depletion of Nav1 also induces transient membrane blebbing via disruption of signaling in the Rho GTPase signaling pathway, supporting the novel role of Nav1 in dynamic actin-based membrane regulation at the cell periphery. These data demonstrate that Nav1 works at the interface of microtubules, actin, and plasma membrane to organize the cell periphery and promote uptake of growth and guidance cues to facilitate neural morphogenesis during development.
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Affiliation(s)
- Regina M. Powers
- Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093,Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037
| | - Ray Daza
- Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037,Department of Pathology, University of California, San Diego, La Jolla, CA 92161
| | - Alanna E. Koehler
- Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037,Department of Pathology, University of California, San Diego, La Jolla, CA 92161
| | - Julien Courchet
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon I, 69008 Lyon Cedex, France
| | - Barbara Calabrese
- Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093,Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037
| | - Robert F. Hevner
- Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037,Department of Pathology, University of California, San Diego, La Jolla, CA 92161
| | - Shelley Halpain
- Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093,Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037,*Address correspondence to: Shelley Halpain ()
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Higgs VE, Das RM. Establishing neuronal polarity: microtubule regulation during neurite initiation. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac007. [PMID: 38596701 PMCID: PMC10913830 DOI: 10.1093/oons/kvac007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/25/2022] [Accepted: 05/02/2022] [Indexed: 04/11/2024]
Abstract
The initiation of nascent projections, or neurites, from the neuronal cell body is the first stage in the formation of axons and dendrites, and thus a critical step in the establishment of neuronal architecture and nervous system development. Neurite formation relies on the polarized remodelling of microtubules, which dynamically direct and reinforce cell shape, and provide tracks for cargo transport and force generation. Within neurons, microtubule behaviour and structure are tightly controlled by an array of regulatory factors. Although microtubule regulation in the later stages of axon development is relatively well understood, how microtubules are regulated during neurite initiation is rarely examined. Here, we discuss how factors that direct microtubule growth, remodelling, stability and positioning influence neurite formation. In addition, we consider microtubule organization by the centrosome and modulation by the actin and intermediate filament networks to provide an up-to-date picture of this vital stage in neuronal development.
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Affiliation(s)
- Victoria E Higgs
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Raman M Das
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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8
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Hoff KJ, Aiken JE, Gutierrez MA, Franco SJ, Moore JK. Tubulinopathy mutations in TUBA1A that disrupt neuronal morphogenesis and migration override XMAP215/Stu2 regulation of microtubule dynamics. eLife 2022; 11:76189. [PMID: 35511030 PMCID: PMC9236607 DOI: 10.7554/elife.76189] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
Heterozygous, missense mutations in α- or β-tubulin genes are associated with a wide range of human brain malformations, known as tubulinopathies. We seek to understand whether a mutation’s impact at the molecular and cellular levels scale with the severity of brain malformation. Here, we focus on two mutations at the valine 409 residue of TUBA1A, V409I, and V409A, identified in patients with pachygyria or lissencephaly, respectively. We find that ectopic expression of TUBA1A-V409I/A mutants disrupt neuronal migration in mice and promote excessive neurite branching and a decrease in the number of neurite retraction events in primary rat neuronal cultures. These neuronal phenotypes are accompanied by increased microtubule acetylation and polymerization rates. To determine the molecular mechanisms, we modeled the V409I/A mutants in budding yeast and found that they promote intrinsically faster microtubule polymerization rates in cells and in reconstitution experiments with purified tubulin. In addition, V409I/A mutants decrease the recruitment of XMAP215/Stu2 to plus ends in budding yeast and ablate tubulin binding to TOG (tumor overexpressed gene) domains. In each assay tested, the TUBA1A-V409I mutant exhibits an intermediate phenotype between wild type and the more severe TUBA1A-V409A, reflecting the severity observed in brain malformations. Together, our data support a model in which the V409I/A mutations disrupt microtubule regulation typically conferred by XMAP215 proteins during neuronal morphogenesis and migration, and this impact on tubulin activity at the molecular level scales with the impact at the cellular and tissue levels. Proteins are molecules made up of long chains of building blocks called amino acids. When a mutation changes one of these amino acids, it can lead to the protein malfunctioning, which can have many effects at the cell and tissue level. Given that human proteins are made up of 20 different amino acids, each building block in a protein could mutate to any of the other 19 amino acids, and each mutations could have different effects. Tubulins are proteins that form microtubules, thin tubes that help give cells their shape and allow them to migrate. These proteins are added or removed to microtubules depending on the cell’s needs, meaning that microtubules can grow or shrink depending on the situation. Mutations in the tubulin proteins have been linked to malformations of varying severities involving the formation of ridges and folds on the surface of the brain, including lissencephaly, pachygyria or polymicrogyria. Hoff et al. wanted to establish links between tubulin mutations and the effects observed at both cell and tissue level in the brain. They focused on two mutations in the tubulin protein TUBA1A that affect the amino acid in position 409 in the protein, which is normally a valine. One of the mutations turns this valine into an amino acid called isoleucine. This mutation is associated with pachygyria, which leads to the brain developing few ridges that are broad and flat. The second mutation turns the valine into an alanine, and is linked to lissencephaly, a more severe condition in which the brain develops no ridges, appearing smooth. Hoff et al. found that both mutations interfere with the development of the brain by stopping neurons from migrating properly, which prevents them from forming the folds in the brain correctly. At the cellular level, the mutations lead to tubulins becoming harder to remove from microtubules, making microtubules more stable than usual. This results in longer microtubules that are harder for the cell to shorten or destroy as needed. Additionally, Hoff et al. showed that the mutant versions of TUBA1A have weaker interactions with a protein called XMAP215, which controls the addition of tubulin to microtubules. This causes the microtubules to grow uncontrollably. Hoff et al. also established that the magnitude of the effects of each mutation on microtubule growth scale with the severity of the disorder they cause. Specifically, cells in which TUBA1A is not mutated have microtubules that grow at a normal rate, and lead to typical brain development. Meanwhile, cells carrying the mutation that turns a valine into an alanine, which is linked to the more severe condition lissencephaly, have microtubules that grow very fast. Finally, cells in which the valine is mutated to an isoleucine – the mutation associated with the less severe malformation pachygyria – have microtubules that grow at an intermediate rate. These findings provide a link between mutations in tubulin proteins and larger effects on cell movement that lead to brain malformations. Additionally, they also link the severity of the malformation to the severity of the microtubule defect caused by each mutation. Further work could examine whether microtubule stabilization is also seen in other similar diseases, which, in the long term, could reveal ways to detect and treat these illnesses.
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Affiliation(s)
- Katelyn J Hoff
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Jayne E Aiken
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Mark A Gutierrez
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Santos J Franco
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Jeffrey K Moore
- University of Colorado School of Medicine, Aurora, United States
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9
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Muthu SJ, Lakshmanan G, Shimray KW, Kaliyappan K, Sathyanathan SB, Seppan P. Testosterone Influence on Microtubule-Associated Proteins and Spine Density in Hippocampus: Implications on Learning and Memory. Dev Neurosci 2022; 44:498-507. [PMID: 35609517 DOI: 10.1159/000525038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/26/2022] [Indexed: 11/19/2022] Open
Abstract
The thorny protrusions or spines increase the neuronal surface area, facilitate synaptic interconnections among neurons, and play an essential role in the hippocampus. Increasing evidence suggests that testosterone, the gonadal hormone, plays an important role in neurogenesis and synaptic plasticity. The role of testosterone on microtubule-associated proteins on dendritic neurite stability in the hippocampus and its impact on learning disability is not elucidated. Adult male Wistar albino rats were randomly selected for the control, castrated, castrated + testosterone, and control + testosterone groups. Bilateral orchidectomy was done, and the testosterone propionate was administered during the entire trial period, i.e., 14 days. The learning assessments were done using working/reference memory versions of the 8-arm radial maze and hippocampal tissues processed for histological and protein expressions. There were reduced expressions of microtubule-associated protein 2 (MAP2), postsynaptic density protein 95 (PSD95), and androgen receptor (AR) and increased expression of pTau in the castrated group. Conversely, the expression of MAP2, PSD95, and AR was increased, and the pTau expression was reduced in the hippocampus of the castrated rat administrated with testosterone. Androgen-depleted rats showed impaired synaptic plasticity in the hippocampus associated with contracted microtubule dynamics. Along with learning disability, there was an increased number of reference memory errors and working memory errors in castrated rats. Observations suggest that androgen regulates expression of neural tissue-specific MAPs and plays a vital role in hippocampus synaptic plasticity and that a similar mechanism may underlie neurological disorders in aging and hypogonadal men.
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Affiliation(s)
- Sakthi Jothi Muthu
- Department of Anatomy, Dr. Arcot Lakshmanasamy Mudaliar Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | - Ganesh Lakshmanan
- Department of Anatomy, Dr. Arcot Lakshmanasamy Mudaliar Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | - Khayinmi Wungpam Shimray
- Department of Anatomy, Dr. Arcot Lakshmanasamy Mudaliar Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | - Kathiravan Kaliyappan
- Department of Anatomy, Dr. Arcot Lakshmanasamy Mudaliar Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | | | - Prakash Seppan
- Department of Anatomy, Dr. Arcot Lakshmanasamy Mudaliar Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
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10
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Sánchez-Huertas C, Herrera E. With the Permission of Microtubules: An Updated Overview on Microtubule Function During Axon Pathfinding. Front Mol Neurosci 2021; 14:759404. [PMID: 34924953 PMCID: PMC8675249 DOI: 10.3389/fnmol.2021.759404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/01/2021] [Indexed: 01/27/2023] Open
Abstract
During the establishment of neural circuitry axons often need to cover long distances to reach remote targets. The stereotyped navigation of these axons defines the connectivity between brain regions and cellular subtypes. This chemotrophic guidance process mostly relies on the spatio-temporal expression patterns of extracellular proteins and the selective expression of their receptors in projection neurons. Axon guidance is stimulated by guidance proteins and implemented by neuronal traction forces at the growth cones, which engage local cytoskeleton regulators and cell adhesion proteins. Different layers of guidance signaling regulation, such as the cleavage and processing of receptors, the expression of co-receptors and a wide variety of intracellular cascades downstream of receptors activation, have been progressively unveiled. Also, in the last decades, the regulation of microtubule (MT) assembly, stability and interactions with the submembranous actin network in the growth cone have emerged as crucial effector mechanisms in axon pathfinding. In this review, we will delve into the intracellular signaling cascades downstream of guidance receptors that converge on the MT cytoskeleton of the growing axon. In particular, we will focus on the microtubule-associated proteins (MAPs) network responsible of MT dynamics in the axon and growth cone. Complementarily, we will discuss new evidences that connect defects in MT scaffold proteins, MAPs or MT-based motors and axon misrouting during brain development.
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Affiliation(s)
- Carlos Sánchez-Huertas
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández (CSIC-UMH), Alicante, Spain
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11
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Agbaegbu Iweka C, Hussein RK, Yu P, Katagiri Y, Geller HM. The lipid phosphatase-like protein PLPPR1 associates with RhoGDI1 to modulate RhoA activation in response to axon growth inhibitory molecules. J Neurochem 2021; 157:494-507. [PMID: 33320336 DOI: 10.1111/jnc.15271] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 11/29/2022]
Abstract
Phospholipid Phosphatase-Related Protein Type 1 (PLPPR1) is a member of a family of lipid phosphatase related proteins, integral membrane proteins characterized by six transmembrane domains. This family of proteins is enriched in the brain and recent data indicate potential pleiotropic functions in several different contexts. An inherent ability of this family of proteins is to induce morphological changes, and we have previously reported that members of this family interact with each other and may function co-operatively. However, the function of PLPPR1 is not yet understood. Here we show that the expression of PLPPR1 reduces the inhibition of neurite outgrowth of cultured mouse hippocampal neurons by chondroitin sulfate proteoglycans and the retraction of neurites of Neuro-2a cells by lysophosphatidic acid (LPA). Further, we show that PLPPR1 reduces the activation of Ras homolog family member A (RhoA) by LPA in Neuro-2a cells, and that this is because of an association of PLPPR1with the Rho-specific guanine nucleotide dissociation inhibitor (RhoGDI1). These results establish a novel signaling pathway for the PLPPR1 protein.
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Affiliation(s)
- Chinyere Agbaegbu Iweka
- Laboratory of Developmental Neurobiology, National Heart Lung and Blood Institute, NIH, Bethesda, MD, USA.,Department of Neuroscience, Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, USA
| | - Rowan K Hussein
- Laboratory of Developmental Neurobiology, National Heart Lung and Blood Institute, NIH, Bethesda, MD, USA
| | - Panpan Yu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Yasuhiro Katagiri
- Laboratory of Developmental Neurobiology, National Heart Lung and Blood Institute, NIH, Bethesda, MD, USA
| | - Herbert M Geller
- Laboratory of Developmental Neurobiology, National Heart Lung and Blood Institute, NIH, Bethesda, MD, USA
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12
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Taran AS, Shuvalova LD, Lagarkova MA, Alieva IB. Huntington's Disease-An Outlook on the Interplay of the HTT Protein, Microtubules and Actin Cytoskeletal Components. Cells 2020; 9:E1514. [PMID: 32580314 PMCID: PMC7348758 DOI: 10.3390/cells9061514] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 12/13/2022] Open
Abstract
Huntington's disease is a severe and currently incurable neurodegenerative disease. An autosomal dominant mutation in the Huntingtin gene (HTT) causes an increase in the polyglutamine fragment length at the protein N-terminus. The consequence of the mutation is the death of neurons, mostly striatal neurons, leading to the occurrence of a complex of motor, cognitive and emotional-volitional personality sphere disorders in carriers. Despite intensive studies, the functions of both mutant and wild-type huntingtin remain poorly understood. Surprisingly, there is the selective effect of the mutant form of HTT even on nervous tissue, whereas the protein is expressed ubiquitously. Huntingtin plays a role in cell physiology and affects cell transport, endocytosis, protein degradation and other cellular and molecular processes. Our experimental data mining let us conclude that a significant part of the Huntingtin-involved cellular processes is mediated by microtubules and other cytoskeletal cell structures. The review attempts to look at unresolved issues in the study of the huntingtin and its mutant form, including their functions affecting microtubules and other components of the cell cytoskeleton.
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Affiliation(s)
- Aleksandra S. Taran
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 1–73, Leninsky Gory, 119992 Moscow, Russia; (A.S.T.); (L.D.S.)
| | - Lilia D. Shuvalova
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 1–73, Leninsky Gory, 119992 Moscow, Russia; (A.S.T.); (L.D.S.)
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
| | - Maria A. Lagarkova
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
| | - Irina B. Alieva
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1–40, Leninsky Gory, 119992 Moscow, Russia
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13
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Jakobs MAH, Franze K, Zemel A. Mechanical Regulation of Neurite Polarization and Growth: A Computational Study. Biophys J 2020; 118:1914-1920. [PMID: 32229314 DOI: 10.1016/j.bpj.2020.02.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 02/19/2020] [Accepted: 02/27/2020] [Indexed: 01/14/2023] Open
Abstract
The densely packed microtubule (MT) array found in neuronal cell projections (neurites) serves two fundamental functions simultaneously: it provides a mechanically stable track for molecular motor-based transport and produces forces that drive neurite growth. The local pattern of MT polarity along the neurite shaft has been found to differ between axons and dendrites. In axons, the neurons' dominating long projections, roughly 90% of the MTs orient with their rapidly growing plus end away from the cell body, whereas in vertebrate dendrites, their orientations are locally mixed. Molecular motors are known to be responsible for cytoskeletal ordering and force generation, but their collective function in the dense MT cytoskeleton of neurites remains elusive. We here hypothesized that both the polarity pattern of MTs along the neurite shaft and the shaft's global extension are simultaneously driven by molecular motor forces and should thus be regulated by the mechanical load acting on the MT array as a whole. To investigate this, we simulated cylindrical bundles of MTs that are cross-linked and powered by molecular motors by iteratively solving a set of force-balance equations. The bundles were subjected to a fixed load arising from actively generated tension in the actomyosin cortex enveloping the MTs. The magnitude of the load and the level of motor-induced connectivity between the MTs have been varied systematically. With an increasing load and decreasing motor-induced connectivity between MTs, the bundles became wider in cross section and extended more slowly, and the local MT orientational order was reduced. These results reveal two, to our knowledge, novel mechanical factors that may underlie the distinctive development of the MT cytoskeleton in axons and dendrites: the cross-linking level of MTs by motors and the load acting on this cytoskeleton during growth.
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Affiliation(s)
- Maximilian A H Jakobs
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Assaf Zemel
- Institute of Dental Sciences and Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem, Jerusalem, Israel.
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14
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Wang Y, Zhang X, Tian J, Shan J, Hu Y, Zhai Y, Guo J. Talin promotes integrin activation accompanied by generation of tension in talin and an increase in osmotic pressure in neurite outgrowth. FASEB J 2019; 33:6311-6326. [PMID: 30768370 DOI: 10.1096/fj.201801949rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Neuronal polarization depends on the interaction of intracellular chemical and mechanical activities in which the cytoplasmic protein, talin, plays a pivotal role during neurite growth. To better understand the mechanism underlying talin function in neuronal polarization, we overexpressed several truncated forms of talin and found that the presence of the rod domain within the overexpressed talin is required for its positive effect on neurite elongation because the neurite number only increased when the talin head region was overexpressed. The tension in the talin rod was recognized using a Förster resonance energy transfer-based tension probe. Nerve growth factor treatment resulted in inward tension of talin elicited by microfilament force and outward osmotic pressure. By contrast, the glial scar-inhibitor aggrecan weakened these forces, suggesting that interactions between inward pull forces in the talin rod and outward osmotic pressure participate in neuronal polarization. Integrin activation is also involved in up-regulation of talin tension and osmotic pressure. Aggrecan stimuli resulted in up-regulation of docking protein 1 (DOK1), leading to the down-regulation of integrin activity and attenuation of the intracellular mechanical force. Our study suggests interactions between the intracellular inward tension in talin and the outward osmotic pressure as the effective channel for promoting neurite outgrowth, which can be up-regulated by integrin activation and down-regulated by DOK1.-Wang, Y., Zhang, X., Tian, J., Shan, J., Hu, Y., Zhai, Y., Guo, J. Talin promotes integrin activation accompanied by generation of tension in talin and an increase in osmotic pressure in neurite outgrowth.
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Affiliation(s)
- Yifan Wang
- State Key Laboratory Cultivation Base for Traditional Chinese Medicine (TCM) Quality and Efficacy, School of Medicine and Life Science, Nanjing University of Chinese Medicine, Nanjing, China
- Key Laboratory of Drug Targets and Drugs for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing, China
| | - Xiaolong Zhang
- State Key Laboratory Cultivation Base for Traditional Chinese Medicine (TCM) Quality and Efficacy, School of Medicine and Life Science, Nanjing University of Chinese Medicine, Nanjing, China
- Key Laboratory of Drug Targets and Drugs for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jilai Tian
- State Key Laboratory Cultivation Base for Traditional Chinese Medicine (TCM) Quality and Efficacy, School of Medicine and Life Science, Nanjing University of Chinese Medicine, Nanjing, China
- Key Laboratory of Drug Targets and Drugs for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jinjun Shan
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yunfeng Hu
- State Key Laboratory Cultivation Base for Traditional Chinese Medicine (TCM) Quality and Efficacy, School of Medicine and Life Science, Nanjing University of Chinese Medicine, Nanjing, China
- Key Laboratory of Drug Targets and Drugs for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yiqian Zhai
- State Key Laboratory Cultivation Base for Traditional Chinese Medicine (TCM) Quality and Efficacy, School of Medicine and Life Science, Nanjing University of Chinese Medicine, Nanjing, China
- Key Laboratory of Drug Targets and Drugs for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jun Guo
- State Key Laboratory Cultivation Base for Traditional Chinese Medicine (TCM) Quality and Efficacy, School of Medicine and Life Science, Nanjing University of Chinese Medicine, Nanjing, China
- Key Laboratory of Drug Targets and Drugs for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing, China
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
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15
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Oelz DB, Del Castillo U, Gelfand VI, Mogilner A. Microtubule Dynamics, Kinesin-1 Sliding, and Dynein Action Drive Growth of Cell Processes. Biophys J 2018; 115:1614-1624. [PMID: 30268540 PMCID: PMC6260207 DOI: 10.1016/j.bpj.2018.08.046] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/14/2018] [Accepted: 08/30/2018] [Indexed: 01/08/2023] Open
Abstract
Recent experimental studies of the role of microtubule sliding in neurite outgrowth suggested a qualitative model, according to which kinesin-1 motors push the minus-end-out microtubules against the cell membrane and generate the early cell processes. At the later stage, dynein takes over the sliding, expels the minus-end-out microtubules from the neurites, and pulls in the plus-end-out microtubules that continue to elongate the nascent axon. This model leaves unanswered a number of questions: why is dynein unable to generate the processes alone, whereas kinesin-1 can? What is the role of microtubule dynamics in process initiation and growth? Can the model correctly predict the rates of process growth in control and dynein-inhibited cases? What triggers the transition from kinesin-driven to dynein-driven sliding? To answer these questions, we combine computational modeling of a network of elastic dynamic microtubules and kinesin-1 and dynein motors with measurements of the process growth kinetics and pharmacological perturbations in Drosophila S2 cells. The results verify quantitatively the qualitative model of the microtubule polarity sorting and suggest that dynein-powered elongation is effective only when the processes are longer than a threshold length, which explains why kinesin-1 alone, but not dynein, is sufficient for the process growth. Furthermore, we show that the mechanism of process elongation depends critically on microtubule dynamic instability. Both modeling and experimental measurements show, surprisingly, that dynein inhibition accelerates the process extension. We discuss implications of the model for the general problems of cell polarization, cytoskeletal polarity emergence, and cell process protrusion.
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Affiliation(s)
- Dietmar B Oelz
- School of Mathematics and Physics, The University of Queensland, Brisbane, Australia
| | - Urko Del Castillo
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Evanston, Illinois
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Evanston, Illinois
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York City, New York.
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16
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Lasser M, Tiber J, Lowery LA. The Role of the Microtubule Cytoskeleton in Neurodevelopmental Disorders. Front Cell Neurosci 2018; 12:165. [PMID: 29962938 PMCID: PMC6010848 DOI: 10.3389/fncel.2018.00165] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/28/2018] [Indexed: 12/28/2022] Open
Abstract
Neurons depend on the highly dynamic microtubule (MT) cytoskeleton for many different processes during early embryonic development including cell division and migration, intracellular trafficking and signal transduction, as well as proper axon guidance and synapse formation. The coordination and support from MTs is crucial for newly formed neurons to migrate appropriately in order to establish neural connections. Once connections are made, MTs provide structural integrity and support to maintain neural connectivity throughout development. Abnormalities in neural migration and connectivity due to genetic mutations of MT-associated proteins can lead to detrimental developmental defects. Growing evidence suggests that these mutations are associated with many different neurodevelopmental disorders, including intellectual disabilities (ID) and autism spectrum disorders (ASD). In this review article, we highlight the crucial role of the MT cytoskeleton in the context of neurodevelopment and summarize genetic mutations of various MT related proteins that may underlie or contribute to neurodevelopmental disorders.
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Affiliation(s)
- Micaela Lasser
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Jessica Tiber
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Laura Anne Lowery
- Department of Biology, Boston College, Chestnut Hill, MA, United States
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17
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Cornell B, Wachi T, Zhukarev V, Toyo-Oka K. Regulation of neuronal morphogenesis by 14-3-3epsilon (Ywhae) via the microtubule binding protein, doublecortin. Hum Mol Genet 2018; 25:4405-4418. [PMID: 28173130 DOI: 10.1093/hmg/ddw270] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 08/03/2016] [Accepted: 08/05/2016] [Indexed: 01/09/2023] Open
Abstract
17p13.3 microduplication syndrome is a newly identified genetic disorder characterized by duplications in the 17p13.3 chromosome locus, resulting in a variety of disorders including autism spectrum disorder (ASD). Importantly, a minimum duplication region has been defined, and this region exclusively contains the gene encoding 14-3-3ε. Furthermore, duplication of this minimum region is strongly associated with the appearance of ASD in human patients, thus implicating the overexpression of 14-3-3ε in ASD. Using in vitro and in vivo techniques, we have found that 14-3-3ε binds to the microtubule binding protein doublecortin preventing its degradation. We also found that 14-3-3ε overexpression disrupts neurite formation by preventing the invasion of microtubules into primitive neurites, which can be rescued by the knockdown of doublecortin. To analyse the function of 14-3-3ε in neurite formation, we used 14-3-3ε flox mice and found that 14-3-3ε deficiency results in an increase in neurite formation. Our findings provide the first evidence of cellular pathology in 17p13.3 microduplication syndrome.
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Affiliation(s)
- Brett Cornell
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA USA
| | - Tomoka Wachi
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA USA
| | - Vladimir Zhukarev
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA USA
| | - Kazuhito Toyo-Oka
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA USA
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18
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An Essential Postdevelopmental Role for Lis1 in Mice. eNeuro 2018; 5:eN-NWR-0350-17. [PMID: 29404402 PMCID: PMC5797476 DOI: 10.1523/eneuro.0350-17.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 01/13/2018] [Accepted: 01/17/2018] [Indexed: 12/15/2022] Open
Abstract
LIS1 mutations cause lissencephaly (LIS), a severe developmental brain malformation. Much less is known about its role in the mature nervous system. LIS1 regulates the microtubule motor cytoplasmic dynein 1 (dynein), and as LIS1 and dynein are both expressed in the adult nervous system, Lis1 could potentially regulate dynein-dependent processes such as axonal transport. We therefore knocked out Lis1 in adult mice using tamoxifen-induced, Cre-ER-mediated recombination. When an actin promoter was used to drive Cre-ER expression (Act-Cre-ER), heterozygous Lis1 knockout (KO) caused no obvious change in viability or behavior, despite evidence of widespread recombination by a Cre reporter three weeks after tamoxifen exposure. In contrast, homozygous Lis1 KO caused the rapid onset of neurological symptoms in both male and female mice. One tamoxifen-dosing regimen caused prominent recombination in the midbrain/hindbrain, PNS, and cardiac/skeletal muscle within a week; these mice developed severe symptoms in that time frame and were killed. A different tamoxifen regimen resulted in delayed recombination in midbrain/hindbrain, but not in other tissues, and also delayed the onset of symptoms. This indicates that Lis1 loss in the midbrain/hindbrain causes the severe phenotype. In support of this, brainstem regions known to house cardiorespiratory centers showed signs of axonal dysfunction in KO animals. Transport defects, neurofilament (NF) alterations, and varicosities were observed in axons in cultured DRG neurons from KO animals. Because no symptoms were observed when a cardiac specific Cre-ER promoter was used, we propose a vital role for Lis1 in autonomic neurons and implicate defective axonal transport in the KO phenotype.
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19
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Lu W, Gelfand VI. Moonlighting Motors: Kinesin, Dynein, and Cell Polarity. Trends Cell Biol 2017; 27:505-514. [PMID: 28284467 DOI: 10.1016/j.tcb.2017.02.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 02/14/2017] [Accepted: 02/15/2017] [Indexed: 01/22/2023]
Abstract
In addition to their well-known role in transporting cargoes in the cytoplasm, microtubule motors organize their own tracks - the microtubules. While this function is mostly studied in the context of cell division, it is essential for microtubule organization and generation of cell polarity in interphase cells. Kinesin-1, the most abundant microtubule motor, plays a role in the initial formation of neurites. This review describes the mechanism of kinesin-1-driven microtubule sliding and discusses its biological significance in neurons. Recent studies describing the interplay between kinesin-1 and cytoplasmic dynein in the translocation of microtubules are discussed. In addition, we evaluate recent work exploring the developmental regulation of microtubule sliding during axonal outgrowth and regeneration. Collectively, the discussed works suggest that sliding of interphase microtubules by motors is a novel force-generating mechanism that reorganizes the cytoskeleton and drives shape change and polarization.
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Affiliation(s)
- Wen Lu
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Ward 11-100, Chicago, IL 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Ward 11-100, Chicago, IL 60611, USA.
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20
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Sharma G, Tsutsumi K, Saito T, Asada A, Ando K, Tomomura M, Hisanaga SI. Kinase activity of endosomal kinase LMTK1A regulates its cellular localization and interactions with cytoskeletons. Genes Cells 2016; 21:1080-1094. [PMID: 27600567 DOI: 10.1111/gtc.12404] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/31/2016] [Indexed: 01/07/2023]
Abstract
Neurite formation, a fundamental process in neuronal maturation, requires the coordinated regulation of cytoskeletal reorganization and membrane transport. Compared to the understanding of cytoskeletal functions, less is known about the supply of membranes to growing neurites. Lemur kinase 1A (LMTK1A) is an endosomal protein kinase that is highly expressed in neurons. We recently reported that LMTK1A regulates the trafficking of Rab11-positive recycling endosomes in growing axons and dendrites. Here, we used the kinase-negative (kn) mutant to investigate the role of the kinase activity of LMTK1A in its cellular localization and interactions with the cytoskeleton in Neuro2A and PC-12 cells. Kinase activity was required for the localization of LMTK1A in the perinuclear endocytic recycling compartment. Perinuclear accumulation was microtubule dependent, and LMTK1A wild type (wt) localized mainly on microtubules, whereas kn LMTK1A was found in the actin-rich cell periphery. In the neurites of PC-12 cells, LMTK1A showed contrasting distributions depending on the kinase activity, with wt being located in the microtubule-rich shaft and the kn form in the actin-rich tip. Taken together, these results suggest that the kinase activity of LMTK1A regulates the pathway for endosomal vesicles to transfer from microtubules to actin filaments at the tip of growing neurites.
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Affiliation(s)
- Govinda Sharma
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Koji Tsutsumi
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Taro Saito
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Akiko Asada
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Kanae Ando
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Mineko Tomomura
- Integral Education Center, Meikai University, Urayasu, Chiba, 279-9950, Japan
| | - Shin-Ichi Hisanaga
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan.
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21
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Braun A, Caesar NM, Dang K, Myers KA. High-resolution Time-lapse Imaging and Automated Analysis of Microtubule Dynamics in Living Human Umbilical Vein Endothelial Cells. J Vis Exp 2016. [PMID: 27584860 PMCID: PMC5091855 DOI: 10.3791/54265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The physiological process by which new vasculature forms from existing vasculature requires specific signaling events that trigger morphological changes within individual endothelial cells (ECs). These processes are critical for homeostatic maintenance such as wound healing, and are also crucial in promoting tumor growth and metastasis. EC morphology is defined by the organization of the cytoskeleton, a tightly regulated system of actin and microtubule (MT) dynamics that is known to control EC branching, polarity and directional migration, essential components of angiogenesis. To study MT dynamics, we used high-resolution fluorescence microscopy coupled with computational image analysis of fluorescently-labeled MT plus-ends to investigate MT growth dynamics and the regulation of EC branching morphology and directional migration. Time-lapse imaging of living Human Umbilical Vein Endothelial Cells (HUVECs) was performed following transfection with fluorescently-labeled MT End Binding protein 3 (EB3) and Mitotic Centromere Associated Kinesin (MCAK)-specific cDNA constructs to evaluate effects on MT dynamics. PlusTipTracker software was used to track EB3-labeled MT plus ends in order to measure MT growth speeds and MT growth lifetimes in time-lapse images. This methodology allows for the study of MT dynamics and the identification of how localized regulation of MT dynamics within sub-cellular regions contributes to the angiogenic processes of EC branching and migration.
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Affiliation(s)
- Alexander Braun
- Department of Biological Sciences, University of the Sciences in Philadelphia
| | - Nicole M Caesar
- Department of Biological Sciences, University of the Sciences in Philadelphia
| | - Kyvan Dang
- Department of Biological Sciences, University of the Sciences in Philadelphia
| | - Kenneth A Myers
- Department of Biological Sciences, University of the Sciences in Philadelphia;
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22
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Pacheco A, Gallo G. Actin filament-microtubule interactions in axon initiation and branching. Brain Res Bull 2016; 126:300-310. [PMID: 27491623 DOI: 10.1016/j.brainresbull.2016.07.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 07/28/2016] [Accepted: 07/30/2016] [Indexed: 10/21/2022]
Abstract
Neurons begin life as spherical cells. A major hallmark of neuronal development is the formation of elongating processes from the cell body which subsequently differentiate into dendrites and the axon. The formation and later development of neuronal processes is achieved through the concerted organization of actin filaments and microtubules. Here, we review the literature regarding recent advances in the understanding of cytoskeletal interactions in neurons focusing on the initiation of processes from neuronal cell bodies and the collateral branching of axons. The complex crosstalk between cytoskeletal elements is mediated by a cohort of proteins that either bind both cytoskeletal systems or allow one to regulate the other. Recent studies have highlighted the importance of microtubule plus-tip proteins in the regulation of the dynamics and organization of actin filaments, while also providing a mechanism for the subcellular capture and guidance of microtubule tips by actin filaments. Although the understanding of cytoskeletal crosstalk and interactions in neuronal morphogenesis has advanced significantly in recent years the appreciation of the neuron as an integrated cytoskeletal system remains a frontier.
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Affiliation(s)
- Almudena Pacheco
- Temple University, Lewis Kats School of Medicine, Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, 3500 North Broad Street, Philadelphia, PA 19140, United States
| | - Gianluca Gallo
- Temple University, Lewis Kats School of Medicine, Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, 3500 North Broad Street, Philadelphia, PA 19140, United States.
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23
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van de Willige D, Hoogenraad CC, Akhmanova A. Microtubule plus-end tracking proteins in neuronal development. Cell Mol Life Sci 2016; 73:2053-77. [PMID: 26969328 PMCID: PMC4834103 DOI: 10.1007/s00018-016-2168-3] [Citation(s) in RCA: 48] [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: 12/13/2015] [Revised: 02/04/2016] [Accepted: 02/22/2016] [Indexed: 11/28/2022]
Abstract
Regulation of the microtubule cytoskeleton is of pivotal importance for neuronal development and function. One such regulatory mechanism centers on microtubule plus-end tracking proteins (+TIPs): structurally and functionally diverse regulatory factors, which can form complex macromolecular assemblies at the growing microtubule plus-ends. +TIPs modulate important properties of microtubules including their dynamics and their ability to control cell polarity, membrane transport and signaling. Several neurodevelopmental and neurodegenerative diseases are associated with mutations in +TIPs or with misregulation of these proteins. In this review, we focus on the role and regulation of +TIPs in neuronal development and associated disorders.
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Affiliation(s)
- Dieudonnée van de Willige
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Casper C Hoogenraad
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - Anna Akhmanova
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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Jing Z, Yin H, Wang P, Gao J, Yuan L. Centlein, a novel microtubule-associated protein stabilizing microtubules and involved in neurite formation. Biochem Biophys Res Commun 2016; 472:360-5. [DOI: 10.1016/j.bbrc.2016.02.079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 02/19/2016] [Indexed: 11/24/2022]
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Audette DS, Scheiblin DA, Duncan MK. The molecular mechanisms underlying lens fiber elongation. Exp Eye Res 2016; 156:41-49. [PMID: 27015931 DOI: 10.1016/j.exer.2016.03.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 03/14/2016] [Accepted: 03/16/2016] [Indexed: 12/28/2022]
Abstract
Lens fiber cells are highly elongated cells with complex membrane morphologies that are critical for the transparency of the ocular lens. Investigations into the molecular mechanisms underlying lens fiber cell elongation were first reported in the 1960s, however, our understanding of the process is still poor nearly 50 years later. This review summarizes what is currently hypothesized about the regulation of lens fiber cell elongation along with the available experimental evidence, and how this information relates to what is known about the regulation of cell shape/elongation in other cell types, particularly neurons.
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Affiliation(s)
- Dylan S Audette
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - David A Scheiblin
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Melinda K Duncan
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA.
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26
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Jakobs M, Franze K, Zemel A. Force Generation by Molecular-Motor-Powered Microtubule Bundles; Implications for Neuronal Polarization and Growth. Front Cell Neurosci 2015; 9:441. [PMID: 26617489 PMCID: PMC4639704 DOI: 10.3389/fncel.2015.00441] [Citation(s) in RCA: 21] [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: 06/24/2015] [Accepted: 10/26/2015] [Indexed: 11/16/2022] Open
Abstract
The heavily cross-linked microtubule (MT) bundles found in neuronal processes play a central role in the initiation, growth and maturation of axons and dendrites; however, a quantitative understanding of their mechanical function is still lacking. We here developed computer simulations to investigate the dynamics of force generation in 1D bundles of MTs that are cross-linked and powered by molecular motors. The motion of filaments and the forces they exert are investigated as a function of the motor type (unipolar or bipolar), MT density and length, applied load, and motor connectivity. We demonstrate that only unipolar motors (e.g., kinesin-1) can provide the driving force for bundle expansion, while bipolar motors (e.g., kinesin-5) oppose it. The force generation capacity of the bundles is shown to depend sharply on the fraction of unipolar motors due to a percolation transition that must occur in the bundle. Scaling laws between bundle length, force, MT length and motor fraction are presented. In addition, we investigate the dynamics of growth in the presence of a constant influx of MTs. Beyond a short equilibration period, the bundles grow linearly in time. In this growth regime, the bundle extends as one mass forward with most filaments sliding with the growth velocity. The growth velocity is shown to be dictated by the inward flux of MTs, to inversely scale with the load and to be independent of the free velocity of the motors. These findings provide important molecular-level insights into the mechanical function of the MT cytoskeleton in normal axon growth and regeneration after injury.
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Affiliation(s)
- Maximilian Jakobs
- Department of Physiology, Development and Neuroscience, University of CambridgeCambridge, UK
- Bonn Cologne Graduate School of Physics and Astronomy, University of CologneCologne, Germany
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of CambridgeCambridge, UK
| | - Assaf Zemel
- Institute of Dental Sciences and Fritz Haber Research Center for Molecular Dynamics, Hebrew University of JerusalemJerusalem, Israel
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Jeruschke S, Jeruschke K, DiStasio A, Karaterzi S, Büscher AK, Nalbant P, Klein-Hitpass L, Hoyer PF, Weiss J, Stottmann RW, Weber S. Everolimus Stabilizes Podocyte Microtubules via Enhancing TUBB2B and DCDC2 Expression. PLoS One 2015; 10:e0137043. [PMID: 26331477 PMCID: PMC4557973 DOI: 10.1371/journal.pone.0137043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 08/12/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Glomerular podocytes are highly differentiated cells that are key components of the kidney filtration units. The podocyte cytoskeleton builds the basis for the dynamic podocyte cytoarchitecture and plays a central role for proper podocyte function. Recent studies implicate that immunosuppressive agents including the mTOR-inhibitor everolimus have a protective role directly on the stability of the podocyte actin cytoskeleton. In contrast, a potential stabilization of microtubules by everolimus has not been studied so far. METHODS To elucidate mechanisms underlying mTOR-inhibitor mediated cytoskeletal rearrangements, we carried out microarray gene expression studies to identify target genes and corresponding pathways in response to everolimus. We analyzed the effect of everolimus in a puromycin aminonucleoside experimental in vitro model of podocyte injury. RESULTS Upon treatment with puromycin aminonucleoside, microarray analysis revealed gene clusters involved in cytoskeletal reorganization, cell adhesion, migration and extracellular matrix composition to be affected. Everolimus was capable of protecting podocytes from injury, both on transcriptional and protein level. Rescued genes included tubulin beta 2B class IIb (TUBB2B) and doublecortin domain containing 2 (DCDC2), both involved in microtubule structure formation in neuronal cells but not identified in podocytes so far. Validating gene expression data, Western-blot analysis in cultured podocytes demonstrated an increase of TUBB2B and DCDC2 protein after everolimus treatment, and immunohistochemistry in healthy control kidneys confirmed a podocyte-specific expression. Interestingly, Tubb2bbrdp/brdp mice revealed a delay in glomerular podocyte development as showed by podocyte-specific markers Wilm's tumour 1, Podocin, Nephrin and Synaptopodin. CONCLUSIONS Taken together, our study suggests that off-target, non-immune mediated effects of the mTOR-inhibitor everolimus on the podocyte cytoskeleton might involve regulation of microtubules, revealing a potential novel role of TUBB2B and DCDC2 in glomerular podocyte development.
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Affiliation(s)
- Stefanie Jeruschke
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
- * E-mail:
| | - Kay Jeruschke
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Duesseldorf, Germany
| | - Andrew DiStasio
- Divisions of Human Genetics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Sinem Karaterzi
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
| | - Anja K. Büscher
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
| | - Perihan Nalbant
- Center for Medical Biotechnology, Molecular Cell Biology, University of Duisburg-Essen, Essen, Germany
| | | | - Peter F. Hoyer
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
| | - Jürgen Weiss
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Duesseldorf, Germany
| | - Rolf W. Stottmann
- Divisions of Human Genetics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Stefanie Weber
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
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Bakos J, Bacova Z, Grant SG, Castejon AM, Ostatnikova D. Are Molecules Involved in Neuritogenesis and Axon Guidance Related to Autism Pathogenesis? Neuromolecular Med 2015; 17:297-304. [PMID: 25989848 DOI: 10.1007/s12017-015-8357-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/08/2015] [Indexed: 12/27/2022]
Abstract
Autism spectrum disorder is a heterogeneous disease, and numerous alterations of gene expression come into play to attempt to explain potential molecular and pathophysiological causes. Abnormalities of brain development and connectivity associated with alterations in cytoskeletal rearrangement, neuritogenesis and elongation of axons and dendrites might represent or contribute to the structural basis of autism pathology. Slit/Robo signaling regulates cytoskeletal remodeling related to axonal and dendritic branching. Components of its signaling pathway (ABL and Cdc42) are suspected to be molecular bases of alterations of normal development. The present review describes the most important mechanisms underlying neuritogenesis, axon pathfinding and the role of GTPases in neurite outgrowth, with special emphasis on alterations associated with autism spectrum disorders. On the basis of analysis of publicly available microarray data, potential biomarkers of autism are discussed.
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Affiliation(s)
- Jan Bakos
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, Bratislava, Slovakia,
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29
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Abstract
Neurons begin their life as simple spheres, but can ultimately assume an elaborate morphology with numerous, highly arborized dendrites, and long axons. This is achieved via an astounding developmental progression which is dependent upon regulated assembly and dynamics of the cellular cytoskeleton. As neurites emerge out of the soma, neurons break their spherical symmetry and begin to acquire the morphological features that define their structure and function. Neurons regulate their cytoskeleton to achieve changes in cell shape, velocity, and direction as they migrate, extend neurites, and polarize. Of particular importance, the organization and dynamics of actin and microtubules directs the migration and morphogenesis of neurons. This review focuses on the regulation of intrinsic properties of the actin and microtubule cytoskeletons and how specific cytoskeletal structures and dynamics are associated with the earliest phase of neuronal morphogenesis—neuritogenesis.
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30
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Duan W, Que L, Lv X, Li Q, Yin H, Zhang L. Tolerance of neurite outgrowth to Rho kinase inhibitors decreased by cyclooxygenase-2 inhibitor. Neural Regen Res 2014; 7:2705-12. [PMID: 25337117 PMCID: PMC4200739 DOI: 10.3969/j.issn.1673-5374.2012.34.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 07/24/2012] [Indexed: 11/21/2022] Open
Abstract
In this study, PC12 Adh cells and Neuro-2a cells were treated with Rho-associated kinase inhibitors (Y27632 and Fasudil), a cyclooxygenase-1 selective inhibitor (SC560), and a cyclooxygenase-2 inhibitor (NS398). We found that these cells became tolerant to Rho-associated kinase inhibitors, as neurite outgrowth induced by these inhibitors diminished following more than 3 days of exposure in either cell line. The proteins cyclooxygenase-2 and cytosolic prostaglandin E synthetase were upregulated at day 3. NS398 decreased the tolerance to neurite outgrowth induction in both cell lines, whereas SC560 had almost no effect. These findings indicate that cells become tolerant to neurite outgrowth induced by Rho-associated kinase inhibitors, this is at least partly associated with upregulation of proteins involved in the cyclooxygenase-2 pathway, and cyclooxygenases-2 inhibition prevents this tolerance.
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Affiliation(s)
- Weigang Duan
- Key Laboratory of Molecular Biology for Sinomedicine, Yunnan University of Traditional Chinese Medicine, Kunming 650500, Yunnan Province, China
| | - Ling Que
- Key Laboratory of Molecular Biology for Sinomedicine, Yunnan University of Traditional Chinese Medicine, Kunming 650500, Yunnan Province, China
| | - Xiaoman Lv
- Key Laboratory of Molecular Biology for Sinomedicine, Yunnan University of Traditional Chinese Medicine, Kunming 650500, Yunnan Province, China
| | - Qifeng Li
- Key Laboratory of Molecular Biology for Sinomedicine, Yunnan University of Traditional Chinese Medicine, Kunming 650500, Yunnan Province, China
| | - Hua Yin
- Key Laboratory of Molecular Biology for Sinomedicine, Yunnan University of Traditional Chinese Medicine, Kunming 650500, Yunnan Province, China
| | - Luyong Zhang
- New Drug Screening Center, China Pharmaceutical University, Nanjing 210009, Jiangsu Province, China
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31
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Braun A, Dang K, Buslig F, Baird MA, Davidson MW, Waterman CM, Myers KA. Rac1 and Aurora A regulate MCAK to polarize microtubule growth in migrating endothelial cells. ACTA ACUST UNITED AC 2014; 206:97-112. [PMID: 25002679 PMCID: PMC4085700 DOI: 10.1083/jcb.201401063] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A Rac1–Aurora A–MCAK signaling pathway mediates endothelial cell polarization and directional migration by promoting regional differences in microtubule dynamics in the leading and trailing cell edges. Endothelial cells (ECs) migrate directionally during angiogenesis and wound healing by polarizing to extracellular cues to guide directional movement. EC polarization is controlled by microtubule (MT) growth dynamics, which are regulated by MT-associated proteins (MAPs) that alter MT stability. Mitotic centromere-associated kinesin (MCAK) is a MAP that promotes MT disassembly within the mitotic spindle, yet its function in regulating MT dynamics to promote EC polarity and migration has not been investigated. We used high-resolution fluorescence microscopy coupled with computational image analysis to elucidate the role of MCAK in regulating MT growth dynamics, morphology, and directional migration of ECs. Our results show that MCAK-mediated depolymerization of MTs is specifically targeted to the trailing edge of polarized wound-edge ECs. Regulation of MCAK function is dependent on Aurora A kinase, which is regionally enhanced by signaling from the small guanosine triphosphatase, Rac1. Thus, a Rac1–Aurora A–MCAK signaling pathway mediates EC polarization and directional migration by promoting regional differences in MT dynamics in the leading and trailing cell edges.
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Affiliation(s)
- Alexander Braun
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA 19104
| | - Kyvan Dang
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA 19104
| | - Felinah Buslig
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA 19104
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, The Florida State University, Tallahassee, FL 32310 National High Magnetic Field Laboratory and Department of Biological Science, The Florida State University, Tallahassee, FL 32310
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, The Florida State University, Tallahassee, FL 32310 National High Magnetic Field Laboratory and Department of Biological Science, The Florida State University, Tallahassee, FL 32310
| | - Clare M Waterman
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Kenneth A Myers
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA 19104 Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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32
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Cytoskeletal and signaling mechanisms of neurite formation. Cell Tissue Res 2014; 359:267-78. [PMID: 25080065 DOI: 10.1007/s00441-014-1955-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 07/01/2014] [Indexed: 10/25/2022]
Abstract
The formation of a neurite, the basis for axons and dendrites, begins with the concerted accumulation and organization of actin and microtubules. Whereas much is known about the proteins that play a role in these processes, because they perform similar functions in axon branching and filopodia formation, much remains to be discovered concerning the interaction of these individual cytoskeletal regulators during neurite formation. Here, we review the literature regarding various models of filopodial formation and the way in which proteins that control actin organization and polymerization induce neurite formation. Although several different regulators of actin polymerization are involved in neurite initiation, redundancy occurs between these regulators, as the effects of the loss of a single regulator can be mitigated by the addition of neurite-promoting substrates and proteins. Similar to actin dynamics, both microtubule stabilizing and destabilizing proteins play a role in neurite initiation. Furthermore, interactions between the actin and microtubule cytoskeleton are required for neurite formation. Several lines of evidence indicate that the interactions between these two components of the cytoskeleton are needed for force generation and for the localization of microtubules at sites of nascent neurites. The general theme that emerges is the existence of several central regulatory pathways on which extracellular cues converge to control and organize both actin and microtubules to induce the formation of neurites.
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Roossien DH, Lamoureux P, Miller KE. Cytoplasmic dynein pushes the cytoskeletal meshwork forward during axonal elongation. J Cell Sci 2014; 127:3593-602. [PMID: 24951117 DOI: 10.1242/jcs.152611] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
During development, neurons send out axonal processes that can reach lengths hundreds of times longer than the diameter of their cell bodies. Recent studies indicate that en masse microtubule translocation is a significant mechanism underlying axonal elongation, but how cellular forces drive this process is unknown. Cytoplasmic dynein generates forces on microtubules in axons to power their movement through 'stop-and-go' transport, but whether these forces influence the bulk translocation of long microtubules embedded in the cytoskeletal meshwork has not been tested. Here, we use both function-blocking antibodies targeted to the dynein intermediate chain and the pharmacological dynein inhibitor ciliobrevin D to ask whether dynein forces contribute to en bloc cytoskeleton translocation. By tracking docked mitochondria as fiducial markers for bulk cytoskeleton movements, we find that translocation is reduced after dynein disruption. We then directly measure net force generation after dynein disruption and find a dramatic increase in axonal tension. Taken together, these data indicate that dynein generates forces that push the cytoskeletal meshwork forward en masse during axonal elongation.
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Affiliation(s)
- Douglas H Roossien
- Cell and Molecular Biology Program, Michigan State University, 288 Farm Ln Room 336, East Lansing, MI 48824, USA
| | - Phillip Lamoureux
- Department of Zoology, Michigan State University, 288 Farm Ln Room 336, East Lansing, MI 48824, USA
| | - Kyle E Miller
- Department of Zoology, Michigan State University, 288 Farm Ln Room 336, East Lansing, MI 48824, USA
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Abstract
Cellular membranes are constantly reshaped by vesicular fission and fusion as well as by interactions with the dynamic cytoskeleton. Signaling activity at membranes depends on their geometric parameters, such as surface area and curvature; these affect local concentration and thereby regulate the potency of molecular reactions. A membrane's shape is thus inextricably tied to information processing. Here, we review how a trinity of signaling, cytoskeletal dynamics, and membrane shape interact within a closed-loop causality that gives rise to an energy-consuming, self-organized system that changes shape to sense the extracellular environment.
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35
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Abstract
Self-organization of dynamic microtubules via interactions with associated motors plays a critical role in spindle formation. The microtubule-based mechanisms underlying other aspects of cellular morphogenesis, such as the formation and development of protrusions from neuronal cells is less well understood. In a recent study, we investigated the molecular mechanism that underlies the massive reorganization of microtubules induced in non-neuronal cells by expression of the neuronal microtubule stabilizer MAP2c. In that study we directly observed cortical dynein complexes and how they affect the dynamic behavior of motile microtubules in living cells. We found that stationary dynein complexes transiently associate with motile microtubules near the cell cortex and that their rapid turnover facilitates efficient microtubule transport. Here, we discuss our findings in the larger context of cellular morphogenesis with specific focus on self-organizing principles from which cellular shape patterns such as the thin protrusions of neurons can emerge.
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Affiliation(s)
- Leif Dehmelt
- Department of Systemic Cell Biology; Max Planck Institute of Molecular Physiology; Dortmund, Germany; Fakultät für Chemie und Chemische Biologie; Dortmund University of Technology; Dortmund, Germany
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36
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Arens J, Duong TT, Dehmelt L. A morphometric screen identifies specific roles for microtubule-regulating genes in neuronal development of P19 stem cells. PLoS One 2013; 8:e79796. [PMID: 24260302 PMCID: PMC3832585 DOI: 10.1371/journal.pone.0079796] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 09/25/2013] [Indexed: 11/18/2022] Open
Abstract
The first morphological change after neuronal differentiation is the microtubule-dependent initiation of thin cell protrusions called neurites. Here we performed a siRNA-based morphometric screen in P19 stem cells to evaluate the role of 408 microtubule-regulating genes during this early neuromorphogenesis step. This screen uncovered several novel regulatory factors, including specific complex subunits of the microtubule motor dynein involved in neurite initiation and a novel role for the microtubule end-binding protein EB2 in attenuation of neurite outgrowth. Epistasis analysis suggests that competition between EB1 and EB2 regulates neurite length, which links its expression to neurite outgrowth. We propose a model that explains how microtubule regulators can mediate cellular morphogenesis during the early steps of neuronal development by controlling microtubule stabilization and organizing dynein-generated forces.
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Affiliation(s)
- Julia Arens
- Department of Systemic Cell Biology, Max Planck Institute of Molekular Physiology, and Fachbereich Chemische Biologie, Dortmund University of Technology, Dortmund, Germany
| | - Thanh-Thuy Duong
- Department of Systemic Cell Biology, Max Planck Institute of Molekular Physiology, and Fachbereich Chemische Biologie, Dortmund University of Technology, Dortmund, Germany
| | - Leif Dehmelt
- Department of Systemic Cell Biology, Max Planck Institute of Molekular Physiology, and Fachbereich Chemische Biologie, Dortmund University of Technology, Dortmund, Germany
- * E-mail:
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Curthoys NM, Freittag H, Connor A, Desouza M, Brettle M, Poljak A, Hall A, Hardeman E, Schevzov G, Gunning PW, Fath T. Tropomyosins induce neuritogenesis and determine neurite branching patterns in B35 neuroblastoma cells. Mol Cell Neurosci 2013; 58:11-21. [PMID: 24211701 DOI: 10.1016/j.mcn.2013.10.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/21/2013] [Accepted: 10/29/2013] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The actin cytoskeleton is critically involved in the regulation of neurite outgrowth. RESULTS The actin cytoskeleton-associated protein tropomyosin induces neurite outgrowth in B35 neuroblastoma cells and regulates neurite branching in an isoform-dependent manner. CONCLUSIONS Our data indicate that tropomyosins are key regulators of the actin cytoskeleton during neurite outgrowth. SIGNIFICANCE Revealing the molecular machinery that regulates the actin cytoskeleton during neurite outgrowth may provide new therapeutic strategies to promote neurite regeneration after nerve injury. SUMMARY The formation of a branched network of neurites between communicating neurons is required for all higher functions in the nervous system. The dynamics of the actin cytoskeleton is fundamental to morphological changes in cell shape and the establishment of these branched networks. The actin-associated proteins tropomyosins have previously been shown to impact on different aspects of neurite formation. Here we demonstrate that an increased expression of tropomyosins is sufficient to induce the formation of neurites in B35 neuroblastoma cells. Furthermore, our data highlight the functional diversity of different tropomyosin isoforms during neuritogenesis. Tropomyosins differentially impact on the expression levels of the actin filament bundling protein fascin and increase the formation of filopodia along the length of neurites. Our data suggest that tropomyosins are central regulators of actin filament populations which drive distinct aspects of neuronal morphogenesis.
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Affiliation(s)
- Nikki Margarita Curthoys
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia; Oncology Research Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Hannah Freittag
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia; Neuromuscular and Regenerative Medicine Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Andrea Connor
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia; Oncology Research Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Melissa Desouza
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia; Oncology Research Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Merryn Brettle
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Anne Poljak
- Bioanalytical Mass Spectrometry Facility, Bioanalytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Amelia Hall
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Edna Hardeman
- Neuromuscular and Regenerative Medicine Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Galina Schevzov
- Oncology Research Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Peter William Gunning
- Oncology Research Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia
| | - Thomas Fath
- Neurodegeneration and Repair Unit, School of Medical Sciences, The University of New South Wales, Sydney NSW 2052, Australia.
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Mazel T, Biesemann A, Krejczy M, Nowald J, Müller O, Dehmelt L. Direct observation of microtubule pushing by cortical dynein in living cells. Mol Biol Cell 2013; 25:95-106. [PMID: 24173713 PMCID: PMC3873897 DOI: 10.1091/mbc.e13-07-0376] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Single-molecule speckle microscopy and computational modeling reveal the relation between cortical dynein complex dynamics and microtubule behavior in mammalian cells. Experimentally observed rapid turnover of dynein complexes at the cell cortex facilitates their search to efficiently capture and push microtubules with leading plus ends. Microtubules are under the influence of forces mediated by cytoplasmic dynein motors associated with the cell cortex. If such microtubules are free to move, they are rapidly transported inside cells. Here we directly observe fluorescent protein–labeled cortical dynein speckles and motile microtubules. We find that several dynein complex subunits, including the heavy chain, the intermediate chain, and the associated dynactin subunit Dctn1 (also known as p150glued) form spatially resolved, dynamic speckles at the cell cortex, which are preferentially associated with microtubules. Measurements of bleaching and dissociation kinetics at the cell cortex reveal that these speckles often contain multiple labeled dynein heavy-chain molecules and turn over rapidly within seconds. The dynamic behavior of microtubules, such as directional movement, bending, or rotation, is influenced by association with dynein speckles, suggesting a direct physical and functional interaction. Our results support a model in which rapid turnover of cell cortex–associated dynein complexes facilitates their search to efficiently capture and push microtubules directionally with leading plus ends.
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Affiliation(s)
- Tomáš Mazel
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, and Fakultät Chemie, Chemische Biologie, Dortmund University of Technology, 44227 Dortmund, Germany
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Prokop A. The intricate relationship between microtubules and their associated motor proteins during axon growth and maintenance. Neural Dev 2013; 8:17. [PMID: 24010872 PMCID: PMC3846809 DOI: 10.1186/1749-8104-8-17] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 08/14/2013] [Indexed: 12/15/2022] Open
Abstract
The hallmarks of neurons are their slender axons which represent the longest cellular processes of animals and which act as the cables that electrically wire the brain, and the brain to the body. Axons extend along reproducible paths during development and regeneration, and they have to be maintained for the lifetime of an organism. Both axon extension and maintenance essentially depend on the microtubule (MT) cytoskeleton. For this, MTs organize into parallel bundles that are established through extension at the leading axon tips within growth cones, and these bundles then form the architectural backbones, as well as the highways for axonal transport essential for supply and intracellular communication. Axon transport over these enormous distances takes days or even weeks and is a substantial logistical challenge. It is performed by kinesins and dynein/dynactin, which are molecular motors that form close functional links to the MTs they walk along. The intricate machinery which regulates MT dynamics, axonal transport and the motors is essential for nervous system development and function, and its investigation has huge potential to bring urgently required progress in understanding the causes of many developmental and degenerative brain disorders. During the last years new explanations for the highly specific properties of axonal MTs and for their close functional links to motor proteins have emerged, and it has become increasingly clear that motors play active roles also in regulating axonal MT networks. Here, I will provide an overview of these new developments.
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Affiliation(s)
- Andreas Prokop
- Faculty of Life Sciences, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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Shea TB, Lee S. The discontinuous nature of neurofilament transport accommodates both establishment and repair of the axonal neurofilament array. Cytoskeleton (Hoboken) 2012; 70:67-73. [PMID: 23124969 DOI: 10.1002/cm.21087] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/08/2012] [Accepted: 10/11/2012] [Indexed: 12/19/2022]
Abstract
Neurofilaments (NFs) provide structural support to axons. Timely and regional deposition of NFs is essential during axonogenesis, since progressive stabilization of proximal axons is essential to support continued pathfinding of distal axonal regions. NFs undergo short bursts of microtubule-mediated axonal transport interspersed by prolonged pauses. We demonstrate herein that it is this unique "on-off" method of axonal transport, coupled with the ability of NFs to form cation-dependent, phosphomediated lateral associations that allow neurons to mediate the orderly transition from exploratory process to stabilized axon following synaptogenesis. We further demonstrate how this transport method provides for NF maintenance following maturation and encompasses the potential for regeneration.
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Affiliation(s)
- Thomas B Shea
- Department of Biological Sciences, Center for Cellular Neurobiology and Neurodegeneration Research, University of Massachusetts, Lowell, One University Avenue, Lowell, MA 01854, USA.
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Baas PW, Mozgova OI. A novel role for retrograde transport of microtubules in the axon. Cytoskeleton (Hoboken) 2012; 69:416-25. [PMID: 22328357 DOI: 10.1002/cm.21013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 01/26/2012] [Accepted: 01/27/2012] [Indexed: 01/14/2023]
Abstract
Short microtubules move within the axon in both directions. In the past, it had been assumed that all of the short moving microtubules are oriented with their plus-ends distal to the cell body, regardless of their direction of movement. The anterogradely moving microtubules were posited to play critical roles in the establishment, expansion, and maintenance of the axonal microtubule array. There was no known function for the retrogradely moving microtubules. In considering the mechanism of their transport, we had assumed that all of the short microtubules have a plus-end-distal polarity orientation, as is characteristic of the long microtubules that dominate the axon. Here we discuss an alternative hypothesis, namely that the short microtubules moving retrogradely have the opposite polarity orientation of those moving anterogradely. Those that move anterogradely have their plus-ends distal to the cell body while those that move retrogradely have their minus ends distal to the cell body. In this view, retrograde transport is a means for clearing the axon of incorrectly oriented microtubules. This new model, if correct, has profound implications for the manner by which healthy axons preserve their characteristic pattern of microtubule polarity orientation. We speculate that pathological flaws in this mechanism may be a critical factor in the degeneration of axons during disease and injury, as well as in neuropathy caused by microtubule-active drugs.
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Affiliation(s)
- Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, USA.
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Mouton-Liger F, Thomas S, Rattenbach R, Magnol L, Larigaldie V, Ledru A, Herault Y, Verney C, Créau N. PCP4 (PEP19) overexpression induces premature neuronal differentiation associated with Ca(2+) /calmodulin-dependent kinase II-δ activation in mouse models of Down syndrome. J Comp Neurol 2011; 519:2779-802. [PMID: 21491429 DOI: 10.1002/cne.22651] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Pcp4/pep19 is a modulator of Ca(2+) -CaM, a key molecule for calcium signaling, expressed in postmitotic neuroectoderm cells during mouse embryogenesis. The PCP4 gene is located on human chromosome 21 and is present in three copies in Down syndrome (DS). To evaluate the consequences of three copies of this gene on the development of these cells in the nervous system, we constructed a transgenic (TgPCP4) mouse model, with one copy of human PCP4, and investigated the effects in this model and in the Ts1Cje, a mouse model of DS. During embryogenesis, we analyzed 1) the level of pcp4 transcript and protein in the two models; 2) the extent of colabeling for markers of neuronal differentiation (βIII-tubulin, Map2c, calbindin, and calretinin) and pcp4 by immunofluorescence analysis and overall protein levels of these markers by Western blotting; and 3) the rate of activation of CaMKII, a Ca(2+) -CaM target, to evaluate the impact of pcp4 overexpression on the Ca(2+) -CaM signaling pathway. We showed that three copies of the pcp4 gene induced the overexpression of transcripts and proteins during embryogenesis. Pcp4 overexpression 1) induced precocious neuronal differentiation, as shown by the distribution and levels of early neuronal markers; and 2) was associated with an increase in CaMKIIδ activation, confirming involvement in neuronal differentiation in vivo via a Pcp4-Ca(2+) -CaM pathway. TgPCP4 and Ts1Cje mice developed similar modifications, demonstrating that these mechanisms may account for abnormal neuronal development in DS.
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Affiliation(s)
- François Mouton-Liger
- Functional Adaptive Biology (BFA), Centre National de la Recherche Scientifique (CNRS) EAC4413, Université Paris Diderot-Paris7, 75205 Paris Cedex 13, France
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Dehmelt L, Poplawski G, Hwang E, Halpain S. NeuriteQuant: an open source toolkit for high content screens of neuronal morphogenesis. BMC Neurosci 2011; 12:100. [PMID: 21989414 PMCID: PMC3208608 DOI: 10.1186/1471-2202-12-100] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 10/11/2011] [Indexed: 11/30/2022] Open
Abstract
Background To date, some of the most useful and physiologically relevant neuronal cell culture systems, such as high density co-cultures of astrocytes and primary hippocampal neurons, or differentiated stem cell-derived cultures, are characterized by high cell density and partially overlapping cellular structures. Efficient analytical strategies are required to enable rapid, reliable, quantitative analysis of neuronal morphology in these valuable model systems. Results Here we present the development and validation of a novel bioinformatics pipeline called NeuriteQuant. This tool enables fully automated morphological analysis of large-scale image data from neuronal cultures or brain sections that display a high degree of complexity and overlap of neuronal outgrowths. It also provides an efficient web-based tool to review and evaluate the analysis process. In addition to its built-in functionality, NeuriteQuant can be readily extended based on the rich toolset offered by ImageJ and its associated community of developers. As proof of concept we performed automated screens for modulators of neuronal development in cultures of primary neurons and neuronally differentiated P19 stem cells, which demonstrated specific dose-dependent effects on neuronal morphology. Conclusions NeuriteQuant is a freely available open-source tool for the automated analysis and effective review of large-scale high-content screens. It is especially well suited to quantify the effect of experimental manipulations on physiologically relevant neuronal cultures or brain sections that display a high degree of complexity and overlap among neurites or other cellular structures.
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Affiliation(s)
- Leif Dehmelt
- Max-Planck-Institute of Molecular Physiology, Otto-Hahn-Str, 11, 44227 Dortmund, Germany.
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Baas PW, Lin S. Hooks and comets: The story of microtubule polarity orientation in the neuron. Dev Neurobiol 2011; 71:403-18. [PMID: 21557497 DOI: 10.1002/dneu.20818] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
It is widely believed that signature patterns of microtubule polarity orientation within axons and dendrites underlie compositional and morphological differences that distinguish these neuronal processes from one another. Axons of vertebrate neurons display uniformly plus-end-distal microtubules, whereas their dendrites display non-uniformly oriented microtubules. Recent studies on insect neurons suggest that it is the minus-end-distal microtubules that are the critical feature of the dendritic microtubule array, whether or not they are accompanied by plus-end-distal microtubules. Discussed in this article are the history of these findings, their implications for the regulation of neuronal polarity across the animal kingdom, and potential mechanisms by which neurons establish the distinct microtubule polarity patterns that define axons and dendrites.
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Affiliation(s)
- Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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Abstract
Dynamic microtubules are important to maintain neuronal morphology and function, but whether neuronal activity affects the organization of dynamic microtubules is unknown. Here, we show that a protocol to induce NMDA-dependent long-term depression (LTD) rapidly attenuates microtubule dynamics in primary rat hippocampal neurons, removing the microtubule-binding protein EB3 from the growing microtubule plus-ends in dendrites. This effect requires the entry of calcium and is mediated by activation of NR2B-containing NMDA-type glutamate receptor. The rapid NMDA effect is followed by a second, more prolonged response, during which EB3 accumulates along MAP2-positive microtubule bundles in the dendritic shaft. MAP2 is both required and sufficient for this activity-dependent redistribution of EB3. Importantly, NMDA receptor activation suppresses microtubule entry in dendritic spines, whereas overexpression of EB3-GFP prevents NMDA-induced spine shrinkage. These results suggest that short-lasting and long-lasting changes in dendritic microtubule dynamics are important determinants for NMDA-induced LTD.
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Riboldi G, Nizzardo M, Simone C, Falcone M, Bresolin N, Comi GP, Corti S. ALS genetic modifiers that increase survival of SOD1 mice and are suitable for therapeutic development. Prog Neurobiol 2011; 95:133-48. [PMID: 21816207 DOI: 10.1016/j.pneurobio.2011.07.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 07/19/2011] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a frequently fatal motor neuron disease without any cure. To find molecular therapeutic targets, several studies crossed transgenic ALS murine models with animals transgenic for some ALS target genes. We aimed to revise the new discoveries and new works in this field. We selected the 10 most promising genes, according to their capability when down-regulated or up-regulated in ALS animal models, for increasing life span and mitigating disease progression: XBP-1, NogoA and NogoB, dynein, heavy and medium neurofilament, NOX1 and NOX2, MLC-mIGF-1, NSE-VEGF, and MMP-9. Interestingly, some crucial modifier genes have been described as being involved in common pathways, the most significant of which are inflammation and cytoskeletal activities. The endoplasmic reticulum also seems to play an important role in ALS pathogenesis, as it is involved in different selected gene pathways. In addition, these genes have evident links to each other, introducing the hypothesis of a single unknown, common pathway involving all of these identified genes and others to be discovered.
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Affiliation(s)
- Giulietta Riboldi
- Department of Neurological Sciences, Dino Ferrari Centre, University of Milan, IRCCS Fondazione Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy
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Rescue of neurons from undergoing hallmark tau-induced Alzheimer's disease cell pathologies by the antimitotic drug paclitaxel. Neurobiol Dis 2011; 43:163-75. [DOI: 10.1016/j.nbd.2011.03.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/14/2011] [Accepted: 03/06/2011] [Indexed: 11/18/2022] Open
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Dong B, Deng W, Jiang D. Distinct cytoskeleton populations and extensive crosstalk control Ciona notochord tubulogenesis. Development 2011; 138:1631-41. [PMID: 21427145 DOI: 10.1242/dev.057208] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cell elongation is a fundamental process that allows cells and tissues to adopt new shapes and functions. During notochord tubulogenesis in the ascidian Ciona intestinalis, a dramatic elongation of individual cells takes place that lengthens the notochord and, consequently, the entire embryo. We find a novel dynamic actin- and non-muscle myosin II-containing constriction midway along the anteroposterior aspect of each notochord cell during this process. Both actin polymerization and myosin II activity are required for the constriction and cell elongation. Discontinuous localization of myosin II in the constriction indicates that the actomyosin network produces local contractions along the circumference. This reveals basal constriction by the actomyosin network as a novel mechanism for cell elongation. Following elongation, the notochord cells undergo a mesenchymal-epithelial transition and form two apical domains at opposite ends. Extracellular lumens then form at the apical surfaces. We show that cortical actin and Ciona ezrin/radixin/moesin (ERM) are essential for lumen formation and that a polarized network of microtubules, which contributes to lumen development, forms in an actin-dependent manner at the apical cortex. Later in notochord tubulogenesis, when notochord cells initiate a bi-directional crawling movement on the notochordal sheath, the microtubule network rotates 90° and becomes organized as parallel bundles extending towards the leading edges of tractive lamellipodia. This process is required for the correct organization of actin-based protrusions and subsequent lumen coalescence. In summary, we establish the contribution of the actomyosin and microtubule networks to notochord tubulogenesis and reveal extensive crosstalk and regulation between these two cytoskeleton components.
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Affiliation(s)
- Bo Dong
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, Bergen, Norway
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Lee S, Sunil N, Tejada JM, Shea TB. Differential roles of kinesin and dynein in translocation of neurofilaments into axonal neurites. J Cell Sci 2011; 124:1022-31. [PMID: 21363889 DOI: 10.1242/jcs.079046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Neurofilament (NF) subunits translocate within axons as short NFs, non-filamentous punctate structures ('puncta') and diffuse material that might comprise individual subunits and/or oligomers. Transport of NFs into and along axons is mediated by the microtubule (MT) motor proteins kinesin and dynein. Despite being characterized as a retrograde motor, dynein nevertheless participates in anterograde NF transport through associating with long MTs or the actin cortex through its cargo domain; relatively shorter MTs associated with the motor domain are then propelled in an anterograde direction, along with any linked NFs. Here, we show that inhibition of dynein function, through dynamitin overexpression or intracellular delivery of anti-dynein antibody, selectively reduced delivery of GFP-tagged short NFs into the axonal hillock, with a corresponding increase in the delivery of puncta, suggesting that dynein selectively delivered short NFs into axonal neurites. Nocodazole-mediated depletion of short MTs had the same effect. By contrast, intracellular delivery of anti-kinesin antibody inhibited anterograde transport of short NFs and puncta to an equal extent. These findings suggest that anterograde axonal transport of linear NFs is more dependent upon association with translocating MTs (which are themselves translocated by dynein) than is transport of NF puncta or oligomers.
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Affiliation(s)
- Sangmook Lee
- Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts, One University Avenue, Lowell, MA 01854, USA
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Phosphorylation of SCG10/stathmin-2 determines multipolar stage exit and neuronal migration rate. Nat Neurosci 2011; 14:305-13. [DOI: 10.1038/nn.2755] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 01/13/2011] [Indexed: 01/20/2023]
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