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Kulkarni R, Thakur A, Kumar H. Microtubule Dynamics Following Central and Peripheral Nervous System Axotomy. ACS Chem Neurosci 2022; 13:1358-1369. [PMID: 35451811 DOI: 10.1021/acschemneuro.2c00189] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Disturbance in the neuronal network leads to instability in the microtubule (MT) railroad of axons, causing hindrance in the intra-axonal transport and making it difficult to re-establish the broken network. Peripheral nervous system (PNS) neurons can stabilize their MTs, leading to the formation of regeneration-promoting structures called "growth cones". However, central nervous system (CNS) neurons lack this intrinsic reparative capability and, instead, form growth-incompetent structures called "retraction bulbs", which have a disarrayed MT network. It is evident from various studies that although axonal regeneration depends on both cell-extrinsic and cell-intrinsic factors, any therapy that aims at axonal regeneration ultimately converges onto MTs. Understanding the neuronal MT dynamics will help develop effective therapeutic strategies in diseases where the MT network gets disrupted, such as spinal cord injury, traumatic brain injury, multiple sclerosis, and amyotrophic lateral sclerosis. It is also essential to know the factors that aid or inhibit MT stabilization. In this review, we have discussed the MT dynamics postaxotomy in the CNS and PNS, and factors that can directly influence MT stability in various diseases.
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Affiliation(s)
- Riya Kulkarni
- National Institute of Pharmaceutical Education and Research, Ahmedabad, Opposite Air Force Station, Palaj, Gandhinagar, Gujarat 382355, India
| | - Akshata Thakur
- National Institute of Pharmaceutical Education and Research, Ahmedabad, Opposite Air Force Station, Palaj, Gandhinagar, Gujarat 382355, India
| | - Hemant Kumar
- National Institute of Pharmaceutical Education and Research, Ahmedabad, Opposite Air Force Station, Palaj, Gandhinagar, Gujarat 382355, India
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2
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King JR, Kabbani N. Alpha 7 nicotinic receptors attenuate neurite development through calcium activation of calpain at the growth cone. PLoS One 2018; 13:e0197247. [PMID: 29768467 PMCID: PMC5955587 DOI: 10.1371/journal.pone.0197247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/30/2018] [Indexed: 11/18/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (nAChR) is a ligand-gated ion channel that plays an important role in cellular calcium signaling contributing to synaptic development and plasticity, and is a key drug target for the treatment of neurodegenerative conditions such as Alzheimer's disease. Here we show that α7 nAChR mediated calcium signals in differentiating PC12 cells activate the proteolytic enzyme calpain leading to spectrin breakdown, microtubule retraction, and attenuation in neurite growth. Imaging in growth cones confirms that α7 activation decreases EB3 comet motility in a calcium dependent manner as demonstrated by the ability of α7 nAChR, ryanodine, or IP3 receptor antagonists to block the effect of α7 nAChR on growth. α7 nAChR mediated EB3 comet motility, spectrin breakdown, and neurite growth was also inhibited by the addition of the selective calpain blocker calpeptin and attenuated by the expression of an α7 subunit unable to bind Gαq and activate calcium store release. The findings indicate that α7 nAChRs regulate cytoskeletal dynamics through local calcium signals for calpain protease activity.
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Affiliation(s)
- Justin R. King
- School of Systems Biology, George Mason University, Fairfax, Virginia, United States of America
| | - Nadine Kabbani
- School of Systems Biology, George Mason University, Fairfax, Virginia, United States of America
- * E-mail:
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3
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Sainath R, Ketschek A, Grandi L, Gallo G. CSPGs inhibit axon branching by impairing mitochondria-dependent regulation of actin dynamics and axonal translation. Dev Neurobiol 2016; 77:454-473. [PMID: 27429169 DOI: 10.1002/dneu.22420] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/28/2016] [Accepted: 07/14/2016] [Indexed: 12/27/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) inhibit the formation of axon collateral branches. The regulation of the axonal cytoskeleton and mitochondria are important components of the mechanism of branching. Actin-dependent axonal plasticity, reflected in the dynamics of axonal actin patches and filopodia, is greatest along segments of the axon populated by mitochondria. It is reported that CSPGs partially depolarize the membrane potential of axonal mitochondria, which impairs the dynamics of the axonal actin cytoskeleton and decreases the formation and duration of axonal filopodia, the first steps in the mechanism of branching. The effects of CSPGs on actin cytoskeletal dynamics are specific to axon segments populated by mitochondria. In contrast, CSPGs do not affect the microtubule content of axons, or the localization of microtubules into axonal filopodia, a required step in the mechanism of branch formation. It is also reported that CSPGs decrease the mitochondria-dependent axonal translation of cortactin, an actin associated protein involved in branching. Finally, the inhibitory effects of CSPGs on axon branching, actin cytoskeletal dynamics and the axonal translation of cortactin are reversed by culturing neurons with acetyl-l-carnitine, which promotes mitochondrial respiration. Collectively these data indicate that CSPGs impair mitochondrial function in axons, an effect which contributes to the inhibition of axon branching. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 419-437, 2017.
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Affiliation(s)
- Rajiv Sainath
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
| | - Andrea Ketschek
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
| | - Leah Grandi
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
| | - Gianluca Gallo
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
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4
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King JR, Kabbani N. Alpha 7 nicotinic receptor coupling to heterotrimeric G proteins modulates RhoA activation, cytoskeletal motility, and structural growth. J Neurochem 2016; 138:532-45. [DOI: 10.1111/jnc.13660] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/27/2016] [Accepted: 05/06/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Justin R. King
- Department of Molecular Neuroscience; Krasnow Institute for Advanced Study; George Mason University; Fairfax Virginia USA
| | - Nadine Kabbani
- Department of Molecular Neuroscience; Krasnow Institute for Advanced Study; George Mason University; Fairfax Virginia USA
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5
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Cavolo SL, Zhou C, Ketcham SA, Suzuki MM, Ukalovic K, Silverman MA, Schroer TA, Levitan ES. Mycalolide B dissociates dynactin and abolishes retrograde axonal transport of dense-core vesicles. Mol Biol Cell 2015; 26:2664-72. [PMID: 26023088 PMCID: PMC4501363 DOI: 10.1091/mbc.e14-11-1564] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 05/19/2015] [Indexed: 11/21/2022] Open
Abstract
Although dynactin was believed to be a bidirectional facilitator of axonal transport, here mycalolide B is identified as a dynactin dissociator and shown to selectively abolish retrograde axonal transport of dense-core vesicles in hippocampal and Drosophila neurons. Thus dynactin has a strict obligatory unidirectional role in axonal transport. Axonal transport is critical for maintaining synaptic transmission. Of interest, anterograde and retrograde axonal transport appear to be interdependent, as perturbing one directional motor often impairs movement in the opposite direction. Here live imaging of Drosophila and hippocampal neuron dense-core vesicles (DCVs) containing a neuropeptide or brain-derived neurotrophic factor shows that the F-actin depolymerizing macrolide toxin mycalolide B (MB) rapidly and selectively abolishes retrograde, but not anterograde, transport in the axon and the nerve terminal. Latrunculin A does not mimic MB, demonstrating that F-actin depolymerization is not responsible for unidirectional transport inhibition. Given that dynactin initiates retrograde transport and that amino acid sequences implicated in macrolide toxin binding are found in the dynactin component actin-related protein 1, we examined dynactin integrity. Remarkably, cell extract and purified protein experiments show that MB induces disassembly of the dynactin complex. Thus imaging selective retrograde transport inhibition led to the discovery of a small-molecule dynactin disruptor. The rapid unidirectional inhibition by MB suggests that dynactin is absolutely required for retrograde DCV transport but does not directly facilitate ongoing anterograde DCV transport in the axon or nerve terminal. More generally, MB's effects bolster the conclusion that anterograde and retrograde axonal transport are not necessarily interdependent.
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Affiliation(s)
- Samantha L Cavolo
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Chaoming Zhou
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | | | - Matthew M Suzuki
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Kresimir Ukalovic
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Michael A Silverman
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Trina A Schroer
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
| | - Edwin S Levitan
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
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6
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Laht P, Otsus M, Remm J, Veske A. B-plexins control microtubule dynamics and dendrite morphology of hippocampal neurons. Exp Cell Res 2014; 326:174-84. [PMID: 24954409 DOI: 10.1016/j.yexcr.2014.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/09/2014] [Indexed: 11/26/2022]
Abstract
Semaphorins and their receptors plexins are implicated in various processes in the nervous system, but how B-plexins regulate the growth of dendrites remains poorly characterized. We had previously observed that Plexin-B1 and B3 interact with microtubule end-binding proteins (EBs) that are central adapters at growing microtubule tips, and this interaction is involved in neurite growth. Therefore, we hypothesized that plexins regulate microtubule dynamics and through that also dendritogenesis. The role of all three B-plexins was systematically examined in these processes. B-plexins and their ligand Semaphorin-4D influence the dynamics of microtubule tips both EB-dependently and independendently. EB3 as well as Plexin-B1, B2 and B3 turned out to have a significant role in the development of dendritic arbor of rat hippocampal neurons. Our results clearly indicate that semaphorin-plexin-EB pathway is one molecular mechanism how extracellular guidance cues are translated into intracellular mechanics. Taken together, Semaphorin-4D and B-plexins modulate the dynamic behavior of microtubule tips, and are therefore important in neurite growth.
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Affiliation(s)
- Piret Laht
- Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia; Competence Centre for Cancer Research, Tallinn, Estonia
| | - Maarja Otsus
- Competence Centre for Cancer Research, Tallinn, Estonia
| | - Jaanus Remm
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - Andres Veske
- Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia; Competence Centre for Cancer Research, Tallinn, Estonia.
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7
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Nordman JC, Kabbani N. Microtubule dynamics at the growth cone are mediated by α7 nicotinic receptor activation of a Gαq and IP3 receptor pathway. FASEB J 2014; 28:2995-3006. [PMID: 24687992 DOI: 10.1096/fj.14-251439] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The α7 nicotinic receptor (α7) plays an important role in neuronal growth and structural plasticity in the developing brain. We have recently characterized a G-protein-signaling pathway regulated by α7 that directs the growth of neurites in developing neural cells. Now we show that choline activation of α7 promotes a rise in intracellular calcium from local ER stores via Gαq signaling, leading to IP3 receptor (IP3R) activation at the growth cone of differentiating PC12 cells. A mutant α7 significantly attenuated in calcium conductance (D44A; P<0.001) was found to be unable to promote IP3R signaling and calcium store release. In addition, calcium elevation via α7 correlates with a significant attenuation in the rate of microtubule invasion of the growth cone (P<0.001). This process was also attenuated in the D44A mutant and blocked by an inhibitor of the IP3R, suggesting that calcium flow through the α7 channel and activation of the Gαq pathway are necessary for growth. Taken together, the findings reveal an inhibitory mechanism of α7 on cytoskeletal growth via the intracellular calcium activity of the receptor channel and the Gαq signaling pathway at the growth cone.-Nordman, J. C., Kabbani, N. Microtubule dynamics at the growth cone are mediated by α7 nicotinic receptor activation of a Gαq and IP3 receptor pathway.
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Affiliation(s)
- Jacob C Nordman
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, USA
| | - Nadine Kabbani
- Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, USA
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8
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Awakening the stalled axon - surprises in CSPG gradients. Exp Neurol 2014; 254:12-7. [PMID: 24424282 DOI: 10.1016/j.expneurol.2013.12.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/23/2013] [Accepted: 12/25/2013] [Indexed: 01/11/2023]
Abstract
The remarkably poor regeneration of axons seen after injury of the brain and spinal cord can result in permanent loss of neural function. This failure of meaningful regeneration has been attributed to both a low intrinsic growth potential of CNS neurons and extrinsic factors that actively block axon growth in the adult CNS. Injury exacerbates this situation by increasing the expression of and exposure to proteins that actively block axonal growth in the CNS. Much experimental efforts have been aimed at overcoming the extrinsic growth inhibitory environment of the injured brain and spinal cord. A recent publication in Experimental Neurology from Kuboyama and colleagues shows that activation of protein kinase A signaling is responsible for the stalling of axon growth in gradients of CNS inhibitory molecules. This observation is unexpected given the role of cAMP signaling in supporting intrinsic growth mechanisms, emphasizing the need to consider spatial and temporal aspects of intracellular signaling in future strategies for neural repair.
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9
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Yu P, Pisitkun T, Wang G, Wang R, Katagiri Y, Gucek M, Knepper MA, Geller HM. Global analysis of neuronal phosphoproteome regulation by chondroitin sulfate proteoglycans. PLoS One 2013; 8:e59285. [PMID: 23527152 PMCID: PMC3601063 DOI: 10.1371/journal.pone.0059285] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 02/13/2013] [Indexed: 01/01/2023] Open
Abstract
Chondroitin sulfate proteoglycans (CSPGs) are major components of the extracellular matrix which mediate inhibition of axonal regeneration after injury to the central nervous system (CNS). Several neuronal receptors for CSPGs have recently been identified; however, the signaling pathways by which CSPGs restrict axonal growth are still largely unknown. In this study, we applied quantitative phosphoproteomics to investigate the global changes in protein phosphorylation induced by CSPGs in primary neurons. In combination with isobaric Tags for Relative and Absolute Quantitation (iTRAQ) labeling, strong cation exchange chromatography (SCX) fractionation, immobilized metal affinity chromatography (IMAC) and LC-MS/MS, we identified and quantified 2214 unique phosphopeptides corresponding to 1118 phosphoproteins, with 118 changing significantly in abundance with CSPG treatment. The proteins that were regulated by CSPGs included key components of synaptic vesicle trafficking, axon guidance mediated by semaphorins, integrin signaling, cadherin signaling and EGF receptor signaling pathways. A significant number of the regulated proteins are cytoskeletal and related proteins that have been implicated in regulating neurite growth. Another highly represented protein category regulated by CSPGs is nucleic acid binding proteins involved in RNA post-transcriptional regulation. Together, by screening the overall phosphoproteome changes induced by CSPGs, this data expand our understanding of CSPG signaling, which provides new insights into development of strategies for overcoming CSPG inhibition and promoting axonal regeneration after CNS injury.
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Affiliation(s)
- Panpan Yu
- Developmental Neurobiology Section, Cell Biology and Physiology Center, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Trairak Pisitkun
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, Division of Intramural Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Guanghui Wang
- Proteomics Core Facility, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rong Wang
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Bethesda, Maryland, United States of America
| | - Yasuhiro Katagiri
- Developmental Neurobiology Section, Cell Biology and Physiology Center, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marjan Gucek
- Proteomics Core Facility, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mark A. Knepper
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, Division of Intramural Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Herbert M. Geller
- Developmental Neurobiology Section, Cell Biology and Physiology Center, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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10
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Yaka C, Björk P, Schönberg T, Erlandsson A. A Novel In Vitro Injury Model Based on Microcontact Printing Demonstrates Negative Effects of Hydrogen Peroxide on Axonal Regeneration both in Absence and Presence of Glia. J Neurotrauma 2013; 30:392-402. [DOI: 10.1089/neu.2012.2562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Cane Yaka
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | | | | | - Anna Erlandsson
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
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11
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Schwend T, Deaton RJ, Zhang Y, Caterson B, Conrad GW. Corneal sulfated glycosaminoglycans and their effects on trigeminal nerve growth cone behavior in vitro: roles for ECM in cornea innervation. Invest Ophthalmol Vis Sci 2012; 53:8118-37. [PMID: 23132805 PMCID: PMC3522437 DOI: 10.1167/iovs.12-10832] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/16/2012] [Accepted: 10/27/2012] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Sensory trigeminal nerve growth cones innervate the cornea in a highly coordinated fashion. The purpose of this study was to determine if extracellular matrix glycosaminoglycans (ECM-GAGs), including keratan sulfate (KS), dermatan sulfate (DS), and chondroitin sulfate A (CSA) and C (CSC), polymerized in developing eyefronts, may provide guidance cues to nerves during cornea innervation. METHODS Immunostaining using antineuron-specific-β-tubulin and monoclonal antibodies for KS, DS, and CSA/C was performed on eyefronts from embryonic day (E) 9 to E14 and staining visualized by confocal microscopy. Effects of purified GAGs on trigeminal nerve growth cone behavior were tested using in vitro neuronal explant cultures. RESULTS At E9 to E10, nerves exiting the pericorneal nerve ring grew as tight fascicles, advancing straight toward the corneal stroma. In contrast, upon entering the stroma, nerves bifurcated repeatedly as they extended anteriorly toward the epithelium. KS was localized in the path of trigeminal nerves, whereas DS and CSA/C-rich areas were avoided by growth cones. When E10 trigeminal neurons were cultured on different substrates comprised of purified GAG molecules, their neurite growth cone behavior varied depending on GAG type, concentration, and mode of presentation (immobilized versus soluble). High concentrations of immobilized KS, DS, and CSA/C inhibited neurite growth to varying degrees. Neurites traversing lower, permissive concentrations of immobilized DS and CSA/C displayed increased fasciculation and decreased branching, whereas KS caused decreased fasciculation and increased branching. Enzymatic digestion of sulfated GAGs canceled their effects on trigeminal neurons. CONCLUSIONS Data herein suggest that GAGs may direct the movement of trigeminal nerve growth cones innervating the cornea.
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Affiliation(s)
- Tyler Schwend
- From the Division of Biology, Kansas State University, Manhattan, Kansas
| | - Ryan J. Deaton
- Department of Pathology, University of Illinois at Chicago, Chicago, Illinois; and
| | - Yuntao Zhang
- From the Division of Biology, Kansas State University, Manhattan, Kansas
| | - Bruce Caterson
- Connective Tissue Biology Laboratories, School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Gary W. Conrad
- From the Division of Biology, Kansas State University, Manhattan, Kansas
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12
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Meseke M, Cavus E, Förster E. Reelin promotes microtubule dynamics in processes of developing neurons. Histochem Cell Biol 2012; 139:283-97. [PMID: 22990595 DOI: 10.1007/s00418-012-1025-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2012] [Indexed: 11/24/2022]
Abstract
The extracellular matrix protein reelin controls radial migration and layer formation of cortical neurons, in part by modulation of cytoskeletal dynamics. A stabilizing effect of reelin on the actin cytoskeleton has been described recently. However, it is poorly understood how reelin modulates microtubule dynamics. Here, we provide evidence that reelin increases microtubule assembly. This effect is mediated, at least in part, by promoting microtubule plus end dynamics in processes of developing neurons. Thus, we treated primary neuronal cultures with nocodazole to disrupt microtubules. After nocodazole washout, we found microtubule reassembly to be accelerated in the presence of reelin. Moreover, we show that reelin treatment promoted the formation of microtubule plus end binding protein 3 (EB3) comets in developing dendrites, and that EB3 immunostaining in the developing wild-type neocortex is most intense in the reelin-rich marginal zone where leading processes of radially migrating neurons project to. This characteristic EB3 staining pattern was absent in reeler. Also reassembly of nocodazole-dispersed dendritic Golgi apparati, which are closely associated to microtubules, was accelerated by reelin treatment, though with a substantially slower time course when compared to microtubule reassembly. In support of our in vitro results, we found that the subcellular distribution of α-tubulin and acetylated tubulin in reeler cortical sections differed from wild-type and from mice lacking the very low density lipoprotein receptor (VLDLR), known to bind reelin. Taken together, our results suggest that reelin promotes microtubule assembly, at least in part, by increasing microtubule plus end dynamics.
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Affiliation(s)
- Maurice Meseke
- Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
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13
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Yu P, Santiago LY, Katagiri Y, Geller HM. Myosin II activity regulates neurite outgrowth and guidance in response to chondroitin sulfate proteoglycans. J Neurochem 2012; 120:1117-28. [PMID: 22191382 PMCID: PMC3296867 DOI: 10.1111/j.1471-4159.2011.07638.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) are major components of the extracellular matrix in the CNS that inhibit axonal regeneration after CNS injury. Signaling pathways in neurons triggered by CSPGs are still largely unknown. In this study, using well-characterized in vitro assays for neurite outgrowth and neurite guidance, we demonstrate a major role for myosin II in the response of neurons to CSPGs. We found that the phosphorylation of myosin II regulatory light chains is increased by CSPGs. Specific inhibition of myosin II activity with blebbistatin allows growing neurites to cross onto CSPG-rich areas and increases the length of neurites of neurons growing on CSPGs. Using specific gene knockdown, we demonstrate selective roles for myosin IIA and IIB in these processes. Time lapse microscopy and immunocytochemistry demonstrated that CSPGs also inhibit cell adhesion and cell spreading. Inhibition of myosin II selectively accelerated neurite initiation without altering cell adhesion and spreading on CSPGs.
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Affiliation(s)
- Panpan Yu
- Developmental Neurobiology Section, Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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14
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Tymanskyj SR, Scales TM, Gordon-Weeks PR. MAP1B enhances microtubule assembly rates and axon extension rates in developing neurons. Mol Cell Neurosci 2012; 49:110-9. [DOI: 10.1016/j.mcn.2011.10.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 09/28/2011] [Accepted: 10/07/2011] [Indexed: 11/16/2022] Open
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15
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Applegate KT, Besson S, Matov A, Bagonis M, Jaqaman K, Danuser G. plusTipTracker: Quantitative image analysis software for the measurement of microtubule dynamics. J Struct Biol 2011; 176:168-84. [PMID: 21821130 PMCID: PMC3298692 DOI: 10.1016/j.jsb.2011.07.009] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Revised: 07/17/2011] [Accepted: 07/20/2011] [Indexed: 01/10/2023]
Abstract
Here we introduce plusTipTracker, a Matlab-based open source software package that combines automated tracking, data analysis, and visualization tools for movies of fluorescently-labeled microtubule (MT) plus end binding proteins (+TIPs). Although +TIPs mark only phases of MT growth, the plusTipTracker software allows inference of additional MT dynamics, including phases of pause and shrinkage, by linking collinear, sequential growth tracks. The algorithm underlying the reconstruction of full MT trajectories relies on the spatially and temporally global tracking framework described in Jaqaman et al. (2008). Post-processing of track populations yields a wealth of quantitative phenotypic information about MT network architecture that can be explored using several visualization modalities and bioinformatics tools included in plusTipTracker. Graphical user interfaces enable novice Matlab users to track thousands of MTs in minutes. In this paper, we describe the algorithms used by plusTipTracker and show how the package can be used to study regional differences in the relative proportion of MT subpopulations within a single cell. The strategy of grouping +TIP growth tracks for the analysis of MT dynamics has been introduced before (Matov et al., 2010). The numerical methods and analytical functionality incorporated in plusTipTracker substantially advance this previous work in terms of flexibility and robustness. To illustrate the enhanced performance of the new software we thus compare computer-assembled +TIP-marked trajectories to manually-traced MT trajectories from the same movie used in Matov et al. (2010).
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Affiliation(s)
| | | | | | | | - Khuloud Jaqaman
- The Scripps Research Institute, La Jolla, CA 92037, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Gaudenz Danuser
- The Scripps Research Institute, La Jolla, CA 92037, USA
- Harvard Medical School, Boston, MA 02115, USA
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16
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Fukui K, Takatsu H, Koike T, Urano S. Hydrogen peroxide induces neurite degeneration: Prevention by tocotrienols. Free Radic Res 2011; 45:681-91. [PMID: 21417547 DOI: 10.3109/10715762.2011.567984] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Reactive oxygen species (ROS) may attack several types of tissues and chronic exposure to ROS may attenuate various biological functions and increase the risk of several types of serious disorders. It is known that treatments with ROS attack neurons and induce cell death. However, the mechanisms of neuronal change by ROS prior to induction of cell death are not yet understood. Here, it was found that treatment of neurons with low concentrations of hydrogen peroxide induced neurite injury, but not cell death. Unusual bands located above the original collapsin response mediator protein (CRMP)-2 protein were detected by western blotting. Treatment with tocopherol or tocotrienols significantly inhibited these changes in neuro2a cells and cerebellar granule neurons (CGCs). Furthermore, prevention by tocotrienols of hydrogen peroxide-induced neurite degeneration was stronger than that by tocopherol. These findings indicate that neurite beading is one of the early events of neuronal degeneration prior to induction of death of hydrogen peroxide-treated neurons. Treatment with tocotrienols may protect neurite function through its neuroprotective function.
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Affiliation(s)
- Koji Fukui
- Physiological Chemistry Laboratory, Department of Bioscience and Engineering, College of Systems Engineering and Sciences, Shibaura Institute of Technology,Fukasaku 307, Minuma-ku, Saitama, 337-8570, Japan.
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