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Zochodne DW. Growth factors and molecular-driven plasticity in neurological systems. HANDBOOK OF CLINICAL NEUROLOGY 2023; 196:569-598. [PMID: 37620091 DOI: 10.1016/b978-0-323-98817-9.00017-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
It has been almost 70 years since the discovery of nerve growth factor (NGF), a period of a dramatic evolution in our understanding of dynamic growth, regeneration, and rewiring of the nervous system. In 1953, the extraordinary finding that a protein found in mouse submandibular glands generated a halo of outgrowing axons has now redefined our concept of the nervous system connectome. Central and peripheral neurons and their axons or dendrites are no longer considered fixed or static "wiring." Exploiting this molecular-driven plasticity as a therapeutic approach has arrived in the clinic with a slate of new trials and ideas. Neural growth factors (GFs), soluble proteins that alter the behavior of neurons, have expanded in numbers and our understanding of the complexity of their signaling and interactions with other proteins has intensified. However, beyond these "extrinsic" determinants of neuron growth and function are the downstream pathways that impact neurons, ripe for translational development and potentially more important than individual growth factors that may trigger them. Persistent and ongoing nuances in clinical trial design in some of the most intractable and irreversible neurological conditions give hope for connecting new biological ideas with clinical benefits. This review is a targeted update on neural GFs, their signals, and new therapeutic ideas, selected from an expansive literature.
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Affiliation(s)
- Douglas W Zochodne
- Division of Neurology, Department of Medicine and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
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2
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Ha KCH, Sterne-Weiler T, Morris Q, Weatheritt RJ, Blencowe BJ. Differential contribution of transcriptomic regulatory layers in the definition of neuronal identity. Nat Commun 2021; 12:335. [PMID: 33436550 PMCID: PMC7804943 DOI: 10.1038/s41467-020-20483-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/25/2020] [Indexed: 12/23/2022] Open
Abstract
Previous transcriptomic profiling studies have typically focused on separately analyzing mRNA expression, alternative splicing and alternative polyadenylation differences between cell and tissue types. However, the relative contribution of these three transcriptomic regulatory layers to cell type specification is poorly understood. This question is particularly relevant to neurons, given their extensive heterogeneity associated with brain location, morphology and function. In the present study, we generated profiles for the three regulatory layers from developmentally and regionally distinct subpopulations of neurons from the mouse hippocampus and broader nervous system. Multi-omics factor analyses revealed differing contributions of each transcriptomic layer in the discrimination of neurons based on their stage of development, region, and function. Importantly, profiles of differential alternative splicing and polyadenylation better discriminated specific neuronal subtype populations than gene expression patterns. These results provide evidence for differential relative contributions of coordinated gene regulatory layers in the specification of neuronal subtypes.
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Affiliation(s)
- Kevin C H Ha
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5A 1A8, Canada
- Vector Institute, Toronto, ON, M5G 1M1, Canada
- BioSymetrics, Inc., Huntington, New York, NY, USA
| | - Timothy Sterne-Weiler
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Quaid Morris
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5A 1A8, Canada
- Vector Institute, Toronto, ON, M5G 1M1, Canada
- Department of Computer Science, University of Toronto, Toronto, ON, M5S 4G4, Canada
| | - Robert J Weatheritt
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada.
- EMBL Australia, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia.
- St. Vincent Clinical School, University of New South Wales, Darlinghurst, NSW, 2010, Australia.
| | - Benjamin J Blencowe
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5A 1A8, Canada.
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3
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Vasudevan A, Koushika SP. Molecular mechanisms governing axonal transport: a C. elegans perspective. J Neurogenet 2020; 34:282-297. [PMID: 33030066 DOI: 10.1080/01677063.2020.1823385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Axonal transport is integral for maintaining neuronal form and function, and defects in axonal transport have been correlated with several neurological diseases, making it a subject of extensive research over the past several years. The anterograde and retrograde transport machineries are crucial for the delivery and distribution of several cytoskeletal elements, growth factors, organelles and other synaptic cargo. Molecular motors and the neuronal cytoskeleton function as effectors for multiple neuronal processes such as axon outgrowth and synapse formation. This review examines the molecular mechanisms governing axonal transport, specifically highlighting the contribution of studies conducted in C. elegans, which has proved to be a tractable model system in which to identify both novel and conserved regulatory mechanisms of axonal transport.
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Affiliation(s)
- Amruta Vasudevan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sandhya P Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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Pacheco A, Merianda TT, Twiss JL, Gallo G. Mechanism and role of the intra-axonal Calreticulin translation in response to axonal injury. Exp Neurol 2019; 323:113072. [PMID: 31669485 DOI: 10.1016/j.expneurol.2019.113072] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/17/2019] [Accepted: 09/27/2019] [Indexed: 12/12/2022]
Abstract
Following injury, sensory axons locally translate mRNAs that encode proteins needed for the response to injury, locally and through retrograde signaling, and for regeneration. In this study, we addressed the mechanism and role of axotomy-induced intra-axonal translation of the ER chaperone Calreticulin. In vivo peripheral nerve injury increased Calreticulin levels in sensory axons. Using an in vitro model system of sensory neurons amenable to mechanistic dissection we provide evidence that axotomy induces local translation of Calreticulin through PERK (protein kinase RNA-like endoplasmic reticulum kinase) mediated phosphorylation of eIF2α by a mechanism that requires both 5' and 3'UTRs (untranslated regions) elements in Calreticulin mRNA. ShRNA mediated depletion of Calreticulin or inhibition of PERK signaling increased axon retraction following axotomy. In contrast, expression of axonally targeted, but not somatically restricted, Calreticulin mRNA decreased retraction and promoted axon regeneration following axotomy in vitro. Collectively, these data indicate that the intra-axonal translation of Calreticulin in response to axotomy serves to minimize the ensuing retraction, and overexpression of axonally targeted Calreticulin mRNA promotes axon regeneration.
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Affiliation(s)
- Almudena Pacheco
- Temple University School of Medicine, Shriners Pediatric Research Center, Department of Anatomy and Cell Biology, 3500 North Broad St, Philadelphia, PA 19140, United States of America.
| | - Tanuja T Merianda
- Drexel University, Department of Biology, Philadelphia, PA 19104, United States of America
| | - Jeffery L Twiss
- University of South Carolina, Department of Biological Sciences, Columbia 29208, SC, United States of America.
| | - Gianluca Gallo
- Temple University School of Medicine, Shriners Pediatric Research Center, Department of Anatomy and Cell Biology, 3500 North Broad St, Philadelphia, PA 19140, United States of America.
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5
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Chakrabarty N, Jung P. Stochastic models of polymerization-based axonal actin transport. Phys Biol 2019; 16:056001. [PMID: 31195374 DOI: 10.1088/1478-3975/ab29cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent advances in live cell imaging of F-actin structures, combined with pulse-chase imaging and computational modeling have suggested that actin is transported along the axon via biased polymerization of metastable actin fibers (actin trails). This mechanism is distinct from motor driven polymer transport, such as for neurofilaments and can be best described as molecular hitchhiking, where G-actin molecules are intermittently incorporated into actin fibers which grow preferentially in the anterograde direction. In this paper, we discuss how various axonal and actin trail parameters like axon diameter, trail nucleation rates, basal G-actin concentration, and trail length influence the transport rate. These predictions can help guide future experiments to verify this novel protein transport mechanism. We introduce a simplified, analytically solvable model of actin transport which relates these parameters to experimentally measurable quantities. We also discuss why a simple diffusion-based transport mechanism cannot explain bulk actin transport in the axon.
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Affiliation(s)
- Nilaj Chakrabarty
- Department of Physics and Astronomy, Neuroscience Program and Quantitative Biology Institute, Athens, OH 45701, United States of America
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6
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Yarmishyn AA, Kremenskoy M, Batagov AO, Preuss A, Wong JH, Kurochkin IV. Genome-wide analysis of mRNAs associated with mouse peroxisomes. BMC Genomics 2016; 17:1028. [PMID: 28155669 PMCID: PMC5259856 DOI: 10.1186/s12864-016-3330-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Background RNA is often targeted to be localized to the specific subcellular compartments. Specific localization of mRNA is believed to be an important mechanism for targeting their protein products to the locations, where their function is required. Results In this study we performed the genome wide transcriptome analysis of peroxisome preparations from the mouse liver using microarrays. We demonstrate that RNA is absent inside peroxisomes, however it is associated at their exterior via the noncovalent contacts with the membrane proteins. We detect enrichment of specific sets of transcripts in two preparations of peroxisomes, purified with different degrees of stringency. Importantly, among these were mRNAs encoding bona fide peroxisomal proteins, such as peroxins and peroxisomal matrix enzymes involved in beta-oxidation of fatty acids and bile acid biosynthesis. The top-most enriched mRNA, whose association with peroxisomes we confirm microscopically was Hmgcs1, encoding 3-hydroxy-3-methylglutaryl-CoA synthase, a crucial enzyme of cholesterol biosynthesis pathway. We observed significant representation of mRNAs encoding mitochondrial and secreted proteins in the peroxisomal fractions. Conclusions This is a pioneer genome-wide study of localization of mRNAs to peroxisomes that provides foundation for more detailed dissection of mechanisms of RNA targeting to subcellular compartments. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3330-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aliaksandr A Yarmishyn
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Matrix, Singapore, 138671, Singapore
| | - Maksym Kremenskoy
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Matrix, Singapore, 138671, Singapore
| | - Arsen O Batagov
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Matrix, Singapore, 138671, Singapore
| | - Axel Preuss
- Institute of Molecular and Cellular Biology, Agency for Science, Technology and Research (A*STAR), Proteos, Singapore, 138673, Singapore
| | - Jin Huei Wong
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Matrix, Singapore, 138671, Singapore
| | - Igor V Kurochkin
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Matrix, Singapore, 138671, Singapore. .,, Present address: Sysmex Corporation, 4-4-4 Takatsukadai, Nishi-ku, Kobe, 651-2271, Japan.
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7
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Intra-axonal protein synthesis in development and beyond. Int J Dev Neurosci 2016; 55:140-149. [PMID: 26970010 DOI: 10.1016/j.ijdevneu.2016.03.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/03/2016] [Accepted: 03/07/2016] [Indexed: 12/15/2022] Open
Abstract
Proteins can be locally produced in the periphery of a cell, allowing a rapid and spatially precise response to the changes in its environment. This process is especially relevant in highly polarized and morphologically complex cells such as neurons. The study of local translation in axons has evolved from being primarily focused on developing axons, to the notion that also mature axons can produce proteins. Axonal translation has been implied in several physiological and pathological conditions, and in all cases it shares common molecular actors and pathways as well as regulatory mechanisms. Here, we review the main findings in these fields, and attempt to highlight shared principles.
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8
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Kipp M, Wagenknecht N, Beyer C, Samer S, Wuerfel J, Nikoubashman O. Thalamus pathology in multiple sclerosis: from biology to clinical application. Cell Mol Life Sci 2015; 72:1127-47. [PMID: 25417212 PMCID: PMC11113280 DOI: 10.1007/s00018-014-1787-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/29/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
There is a broad consensus that MS represents more than an inflammatory disease: it harbors several characteristic aspects of a classical neurodegenerative disorder, i.e. damage to axons, synapses and nerve cell bodies. While the clinician is equipped with appropriate tools to dampen peripheral cell recruitment and, thus, is able to prevent immune-cell driven relapses, effective therapeutic options to prevent the simultaneously progressing neurodegeneration are still missing. Furthermore, while several sophisticated paraclinical methods exist to monitor the inflammatory-driven aspects of the disease, techniques to monitor progression of early neurodegeneration are still in their infancy and have not been convincingly validated. In this review article, we aim to elaborate why the thalamus with its multiple reciprocal connections is sensitive to pathological processes occurring in different brain regions, thus acting as a "barometer" for diffuse brain parenchymal damage in MS. The thalamus might be, thus, an ideal region of interest to test the effectiveness of new neuroprotective MS drugs. Especially, we will address underlying pathological mechanisms operant during thalamus degeneration in MS, such as trans-neuronal or Wallerian degeneration. Furthermore, we aim at giving an overview about different paraclinical methods used to estimate the extent of thalamic pathology in MS patients, and we discuss their limitations. Finally, thalamus involvement in different MS animal models will be described, and their relevance for the design of preclinical trials elaborated.
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Affiliation(s)
- Markus Kipp
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany,
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9
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Weinkauf B, Obreja O, Schmelz M, Rukwied R. Differential time course of NGF-induced hyperalgesia to heat versus mechanical and electrical stimulation in human skin. Eur J Pain 2014; 19:789-96. [DOI: 10.1002/ejp.603] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2014] [Indexed: 01/24/2023]
Affiliation(s)
- B. Weinkauf
- Department of Anaesthesiology; Medical Faculty Mannheim; University of Heidelberg; Germany
| | - O. Obreja
- Department of Anaesthesiology; Medical Faculty Mannheim; University of Heidelberg; Germany
| | - M. Schmelz
- Department of Anaesthesiology; Medical Faculty Mannheim; University of Heidelberg; Germany
| | - R. Rukwied
- Department of Anaesthesiology; Medical Faculty Mannheim; University of Heidelberg; Germany
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10
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Chaudhury A, De Miranda-Neto MH, Pereira RVF, Zanoni JN. Myosin Va but Not nNOSα is Significantly Reduced in Jejunal Musculomotor Nerve Terminals in Diabetes Mellitus. Front Med (Lausanne) 2014; 1:17. [PMID: 25705628 PMCID: PMC4335397 DOI: 10.3389/fmed.2014.00017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 06/05/2014] [Indexed: 12/18/2022] Open
Abstract
Nitric oxide (NO) mediated slow inhibitory junction potential and mechanical relaxation after electrical field stimulation (EFS) is impaired in diabetes mellitus. Externally added NO donor restore nitrergic function, indicating that this reduction result from diminution of NO synthesis within the pre-junctional nerve terminals. The present study aimed to investigate two specific aims that may potentially provide pathophysiological insights into diabetic nitrergic neuropathy. Specifically, alteration in nNOSα contents within jejunal nerve terminals and a local subcortical transporter myosin Va was tested 16 weeks after induction of diabetes by low dose streptozotocin (STZ) in male Wistar rats. The results show that diabetic rats, in contrast to vehicle treated animals, have: (a) nearly absent myosin Va expression in nerve terminals of axons innervating smooth muscles and (b) significant decrease of myosin Va in neuronal soma of myenteric plexus. In contrast, nNOSα staining in diabetic jejunum neuromuscular strips showed near intact expression in neuronal cell bodies. The space occupancy of nitrergic nerve fibers was comparable between groups. Normal concentration of nNOSα was visualized within a majority of nitrergic terminals in diabetes, suggesting intact axonal transport of nNOSα to distant nerve terminals. These results reveal the dissociation between presences of nNOSα in the nerve terminals but deficiency of its transporter myosin Va in the jejunum of diabetic rats. This significant observation of reduced motor protein myosin Va within jejunal nerve terminals may potentially explain impairment of pre-junctional NO synthesis during EFS of diabetic gut neuromuscular strips despite presence of the nitrergic synthetic enzyme nNOSα.
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Affiliation(s)
- Arun Chaudhury
- Department of Surgery, Brigham and Women's Hospital, Harvard Medical School and VA Boston HealthCare System , West Roxbury, MA , USA
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11
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Jung H, Gkogkas CG, Sonenberg N, Holt CE. Remote control of gene function by local translation. Cell 2014; 157:26-40. [PMID: 24679524 PMCID: PMC3988848 DOI: 10.1016/j.cell.2014.03.005] [Citation(s) in RCA: 233] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 02/04/2014] [Accepted: 03/04/2014] [Indexed: 12/12/2022]
Abstract
The subcellular position of a protein is a key determinant of its function. Mounting evidence indicates that RNA localization, where specific mRNAs are transported subcellularly and subsequently translated in response to localized signals, is an evolutionarily conserved mechanism to control protein localization. On-site synthesis confers novel signaling properties to a protein and helps to maintain local proteome homeostasis. Local translation plays particularly important roles in distal neuronal compartments, and dysregulated RNA localization and translation cause defects in neuronal wiring and survival. Here, we discuss key findings in this area and possible implications of this adaptable and swift mechanism for spatial control of gene function.
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Affiliation(s)
- Hosung Jung
- Department of Anatomy, Brain Research Institute, and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea
| | - Christos G Gkogkas
- Patrick Wild Centre, Centre for Integrative Physiology, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada.
| | - Christine E Holt
- Department of Physiology Development and Neuroscience, Anatomy Building, Downing Street, University of Cambridge, Cambridge CB2 3DY, UK.
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12
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Abstract
Chronic distal symmetrical sensory peripheral neuropathy is a common neurological complication of cancer chemotherapy, HIV treatment and diabetes. Although aetiology-specific differences in presentation are evident, the clinical signs and symptoms of these neuropathies are clearly similar. Data from animal models of neuropathic pain suggest that the similarities have a common cause: mitochondrial dysfunction in primary afferent sensory neurons. Mitochondrial dysfunction is caused by mitotoxic effects of cancer chemotherapeutic drugs of several chemical classes, HIV-associated viral proteins, and nucleoside reverse transcriptase inhibitor treatment, as well as the (possibly both direct and indirect) effects of excess glucose. The mitochondrial injury results in a chronic neuronal energy deficit, which gives rise to spontaneous nerve impulses and a compartmental neuronal degeneration that is first apparent in the terminal receptor arbor--that is, intraepidermal nerve fibres--of cutaneous afferent neurons. Preliminary data suggest that drugs that prevent mitochondrial injury or improve mitochondrial function could be useful in the treatment of these conditions.
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13
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Hjorth JJJ, van Pelt J, Mansvelder HD, van Ooyen A. Competitive dynamics during resource-driven neurite outgrowth. PLoS One 2014; 9:e86741. [PMID: 24498280 PMCID: PMC3911915 DOI: 10.1371/journal.pone.0086741] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 12/17/2013] [Indexed: 11/18/2022] Open
Abstract
Neurons form networks by growing out neurites that synaptically connect to other neurons. During this process, neurites develop complex branched trees. Interestingly, the outgrowth of neurite branches is often accompanied by the simultaneous withdrawal of other branches belonging to the same tree. This apparent competitive outgrowth between branches of the same neuron is relevant for the formation of synaptic connectivity, but the underlying mechanisms are unknown. An essential component of neurites is the cytoskeleton of microtubules, long polymers of tubulin dimers running throughout the entire neurite. To investigate whether competition between neurites can emerge from the dynamics of a resource such as tubulin, we developed a multi-compartmental model of neurite growth. In the model, tubulin is produced in the soma and transported by diffusion and active transport to the growth cones at the tip of the neurites, where it is assembled into microtubules to elongate the neurite. Just as in experimental studies, we find that the outgrowth of a neurite branch can lead to the simultaneous retraction of its neighboring branches. We show that these competitive interactions occur in simple neurite morphologies as well as in complex neurite arborizations and that in developing neurons competition for a growth resource such as tubulin can account for the differential outgrowth of neurite branches. The model predicts that competition between neurite branches decreases with path distance between growth cones, increases with path distance from growth cone to soma, and decreases with a higher rate of active transport. Together, our results suggest that competition between outgrowing neurites can already emerge from relatively simple and basic dynamics of a growth resource. Our findings point to the need to test the model predictions and to determine, by monitoring tubulin concentrations in outgrowing neurons, whether tubulin is the resource for which neurites compete.
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Affiliation(s)
- J J Johannes Hjorth
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Jaap van Pelt
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Arjen van Ooyen
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
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14
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Deregulated mTOR-mediated translation in intellectual disability. Prog Neurobiol 2012; 96:268-82. [DOI: 10.1016/j.pneurobio.2012.01.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 01/02/2012] [Accepted: 01/12/2012] [Indexed: 02/04/2023]
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15
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Abbas AK, Huang FS, Li R, Ekström J, Wigström H. Emetine treatment masks initial LTP without affecting long-term stability. Brain Res 2011; 1426:18-29. [DOI: 10.1016/j.brainres.2011.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 10/04/2011] [Accepted: 10/05/2011] [Indexed: 11/29/2022]
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16
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Jung H, Holt CE. Local translation of mRNAs in neural development. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 2:153-65. [PMID: 21956974 DOI: 10.1002/wrna.53] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Growing axons encounter numerous developmental signals to which they must promptly respond in order to properly form complex neural circuitry. In the axons, these signals are often transduced into a local increase or decrease in protein levels. Contrary to the traditional view that the cell bodies are the exclusive source of axonal proteins, it is becoming increasingly clear not only that de novo protein synthesis takes place in axons, but also that it is required for the axons to respond to certain signals. Here we review the current knowledge of local mRNA translation in developing neurons with a special focus on protein synthesis occurring in axons and growth cones.
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Affiliation(s)
- Hosung Jung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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17
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Day IN, Thompson RJ. UCHL1 (PGP 9.5): Neuronal biomarker and ubiquitin system protein. Prog Neurobiol 2010; 90:327-62. [DOI: 10.1016/j.pneurobio.2009.10.020] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 10/18/2009] [Accepted: 10/21/2009] [Indexed: 12/16/2022]
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18
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Uittenbogaard M, Baxter KK, Chiaramello A. NeuroD6 genomic signature bridging neuronal differentiation to survival via the molecular chaperone network. J Neurosci Res 2010; 88:33-54. [PMID: 19610105 DOI: 10.1002/jnr.22182] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
During neurogenesis, expression of the basic helix-loop-helix NeuroD6/Nex1/MATH-2 transcription factor parallels neuronal differentiation and is maintained in differentiated neurons in the adult brain. To dissect NeuroD6 differentiation properties further, we previously generated a NeuroD6-overexpressing stable PC12 cell line, PC12-ND6, which displays a neuronal phenotype characterized by spontaneous neuritogenesis, accelerated NGF-induced differentiation, and increased regenerative capacity. Furthermore, we reported that NeuroD6 promotes long-term neuronal survival upon serum deprivation. In this study, we identified the NeuroD6-mediated transcriptional regulatory pathways linking neuronal differentiation to survival, by conducting a genome-wide microarray analysis using PC12-ND6 cells and serum deprivation as a stress paradigm. Through a series of filtering steps and a gene-ontology analysis, we found that NeuroD6 promotes distinct but overlapping gene networks, consistent with the differentiation, regeneration, and survival properties of PC12-ND6 cells. By using a gene-set-enrichment analysis, we provide the first evidence of a compelling link between NeuroD6 and a set of heat shock proteins in the absence of stress, which may be instrumental in conferring stress tolerance on PC12-ND6 cells. Immunocytochemistry results showed that HSP27 and HSP70 interact with cytoskeletal elements, consistent with their roles in neuritogenesis and preserving cellular integrity. HSP70 also colocalizes with mitochondria located in the soma, growing neurites, and growth cones of PC12-ND6 cells prior to and upon stress stimulus, consistent with its neuroprotective functions. Collectively, our findings support the notion that NeuroD6 links neuronal differentiation to survival via the network of molecular chaperones and endows the cells with increased stress tolerance.
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Affiliation(s)
- Martine Uittenbogaard
- Department of Anatomy and Regenerative Biology, George Washington University Medical Center, Washington, DC, USA
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19
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Campenot RB, Lund K, Mok SA. Production of compartmented cultures of rat sympathetic neurons. Nat Protoc 2009; 4:1869-87. [DOI: 10.1038/nprot.2009.210] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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20
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Andreassi C, Riccio A. To localize or not to localize: mRNA fate is in 3'UTR ends. Trends Cell Biol 2009; 19:465-74. [PMID: 19716303 DOI: 10.1016/j.tcb.2009.06.001] [Citation(s) in RCA: 257] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 06/17/2009] [Accepted: 06/18/2009] [Indexed: 01/30/2023]
Abstract
Translation of localized mRNA is a fast and efficient way of reacting to extracellular stimuli with the added benefit of providing spatial resolution to the cellular response. The efficacy of this adaptive response ultimately relies on the ability to express a particular protein at the right time and in the right place. Although mRNA localization is a mechanism shared by most organisms, it is especially relevant in highly polarized cells, such as differentiated neurons. 3'-Untranslated regions (3'UTRs) of mRNAs are critical both for the targeting of transcripts to specific subcellular compartments and for translational control. Here we review recent studies that indicate how, in response to extracellular cues, nuclear and cytoplasmic remodeling of the 3'UTR contributes to mRNA localization and local protein synthesis.
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Affiliation(s)
- Catia Andreassi
- MRC Laboratory for Molecular and Cell Biology, University College London, London WC1E 6BT, UK
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Protein synthesis in distal axons is not required for growth cone responses to guidance cues. J Neurosci 2009; 29:638-52. [PMID: 19158291 DOI: 10.1523/jneurosci.3845-08.2009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Recent evidence suggests that growth cone responses to guidance cues require local protein synthesis. Using chick neurons, we investigated whether protein synthesis is required for growth cones of several types to respond to guidance cues. First, we found that global inhibition of protein synthesis stops axonal elongation after 2 h. When protein synthesis inhibitors were added 15 min before adding guidance cues, we found no changes in the typical responses of retinal, sensory, and sympathetic growth cones. In the presence of cycloheximide or anisomycin, ephrin-A2, slit-3, and semaphorin3A still induced growth cone collapse and loss of actin filaments, nerve growth factor (NGF) and neurotrophin-3 still induced growth cone protrusion and increased filamentous actin, and sensory growth cones turned toward an NGF source. In compartmented chambers that separated perikarya from axons, axons grew for 24-48 h in the presence of cycloheximide and responded to negative and positive cues. Our results indicate that protein synthesis is not strictly required in the mechanisms for growth cone responses to many guidance cues. Differences between our results and other studies may exist because of different cellular metabolic levels in in vitro conditions and a difference in when axonal functions become dependent on local protein synthesis.
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O'Toole M, Latham R, Baqri RM, Miller KE. Modeling mitochondrial dynamics during in vivo axonal elongation. J Theor Biol 2008; 255:369-77. [PMID: 18845167 DOI: 10.1016/j.jtbi.2008.09.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 09/03/2008] [Accepted: 09/04/2008] [Indexed: 01/05/2023]
Abstract
Many models of axonal elongation are based on the assumption that the rate of lengthening is driven by the production of cellular materials in the soma. These models make specific predictions about transport and concentration gradients of proteins both over time and along the length of the axon. In vivo, it is well accepted that for a particular neuron the length and rate of growth are controlled by the body size and rate of growth of the animal. In terms of modeling axonal elongation this radically changes the relationships between key variables. It raises fundamental questions. For example, during in vivo lengthening is the production of material constant or does it change over time? What is the density profile of material along the nerve during in vivo elongation? Does density change over time or vary along the nerve? To answer these questions we measured the length, mitochondrial density, and estimated the half-life of mitochondria in the axons of the medial segmental nerves of 1st, 2nd, and 3rd instar Drosophila larvae. The nerves were found to linearly increase in length at an average rate of 9.24 microm h(-1) over the 96 h period of larval life. Further, mitochondrial density increases over this period at an average rate of 4.49x10(-3) (mitochondria microm(-1))h(-1). Mitochondria in the nerves had a half-life of 35.2h. To account for the distribution of the mitochondria we observe, we derived a mathematical model which suggests that cellular production of mitochondria increases quadratically over time and that a homeostatic mechanism maintains a constant density of mitochondria along the nerve. These data suggest a complex relationship between axonal length and mass production and that the neuron may have an "axonal length sensor."
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Affiliation(s)
- Matthew O'Toole
- Department of Mathematics, Michigan State University, A-106 Wells Hall, East Lansing, MI 48824-1115, USA
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23
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Miller KE, Heidemann SR. What is slow axonal transport? Exp Cell Res 2008; 314:1981-90. [DOI: 10.1016/j.yexcr.2008.03.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 02/29/2008] [Accepted: 03/06/2008] [Indexed: 12/26/2022]
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Šatkauskas S, Bagnard D. Local protein synthesis in axonal growth cones: what is next? Cell Adh Migr 2007; 1:179-84. [PMID: 19262143 PMCID: PMC2634104 DOI: 10.4161/cam.1.4.5561] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 01/11/2008] [Indexed: 01/17/2023] Open
Abstract
While initially thought to be essentially a developmental characteristic, observed in artificial in vitro models, local protein synthesis in growth cones has been described in the adult, and more interestingly, during nerve regeneration. This emerging field is under intense investigation, revealing new functions of localized protein synthesis that include axon guidance, growth cone adaptation and sensitivity modulation at intermediate targets or axon regeneration. Here, we will review these functions and provide a short survey of the current knowledge on mechanisms of mRNA transport and regulation of localized protein synthesis. In addition, we will consider what lessons can be learned from localized protein synthesis in dendrites, and what developments can be expected next in the field. This latter question relates to the crucial point of which technical strategy to adopt for an ideal and pertinent analysis of the phenomenon.
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Affiliation(s)
- Saulius Šatkauskas
- INSERM U575 Physiopathologie du Système Nerveux; Strasbourg, France
- Department of Biology; Vytautas Magnus University; Kaunas, Lithuania
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Mark KA, Quinton MS, Russek SJ, Yamamoto BK. Dynamic changes in vesicular glutamate transporter 1 function and expression related to methamphetamine-induced glutamate release. J Neurosci 2007; 27:6823-31. [PMID: 17581970 PMCID: PMC6672707 DOI: 10.1523/jneurosci.0013-07.2007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The vesicular glutamate (GLU) transporter (VGLUT1) is a critical component of glutamatergic neurons that regulates GLU release. Despite the likely role of GLU release in drug abuse pathology, there is no information that links VGLUT1 with drugs of abuse. This study provides the first evidence that methamphetamine (METH) alters the dynamic regulation of striatal VGLUT1 function and expression through a polysynaptic pathway. METH increases cortical VGLUT1 mRNA, striatal VGLUT1 protein in subcellular fractions, and the Vmax of striatal vesicular GLU uptake. METH also increases glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein in the crude vesicle fraction. METH-induced increases in cortical VGLUT1 mRNA, as well as striatal VGLUT1 and GAPDH, are GABA(A) receptor-dependent because they are blocked by GABA(A) receptor antagonism in the substantia nigra. These results show that VGLUT1 can be dynamically regulated via a polysynaptic pathway to facilitate vesicular accumulation of GLU for subsequent release after METH.
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Affiliation(s)
| | | | - Shelley J. Russek
- Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts 02118
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26
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Yin HH, Davis MI, Ronesi JA, Lovinger DM. The role of protein synthesis in striatal long-term depression. J Neurosci 2006; 26:11811-20. [PMID: 17108154 PMCID: PMC6674864 DOI: 10.1523/jneurosci.3196-06.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Long-term depression (LTD) at the corticostriatal synapse is postsynaptically induced but presynaptically expressed, the depression being a result of retrograde endocannabinoid signaling that activates presynaptic cannabinoid CB1 receptors and reduces the probability of glutamate release. To study the role of protein synthesis in striatal LTD, we used a striatum-only preparation in which the presynaptic cell body is cut off, leaving intact only its axons, whose terminals synapse on medium spiny neurons. LTD (duration >150 min) was induced in this preparation, thus providing evidence that transcription in the presynaptic cell nucleus is not necessary for this form of plasticity. The maintenance of striatal LTD, however, was blocked by bath application of protein translation inhibitors but not by the same inhibitors loaded into the postsynaptic cell. These results suggest that local translation is critical for the expression of striatal LTD, distinguishing this form of mammalian synaptic plasticity from other forms that require postsynaptic protein synthesis. Possible roles of axonal or glial translation in striatal LTD are considered.
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Affiliation(s)
- Henry H. Yin
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892
| | - Margaret I. Davis
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892
| | - Jennifer A. Ronesi
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892
| | - David M. Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892
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Abstract
Axonal growth depends on axonal transport. We report the first global analysis of mitochondrial transport during axonal growth and pauses. In the proximal axon, we found that docked mitochondria attached to the cytoskeletal framework that were stationary relative to the substrate and fast axonal transport fully accounted for mitochondrial transport. In the distal axon, we found both fast mitochondrial transport and a coherent slow transport of the mitochondria docked to the axonal framework (low velocity transport [LVT]). LVT was distinct from previously described transport processes; it was coupled with stretching of the axonal framework and, surprisingly, was independent of growth cone advance. Fast mitochondrial transport decreased and LVT increased in a proximodistal gradient along the axon, but together they generated a constant mitochondrial flux. These findings suggest that the viscoelastic stretching/creep of axons caused by tension exerted by the growth cone, with or without advance, is seen as LVT that is followed by compensatory intercalated addition of new mitochondria by fast axonal transport.
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Affiliation(s)
- Kyle E Miller
- Department of Zoology, Michigan State University, East Lansing, MI 48824, USA.
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28
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Chia SM, Lin PC, Quek CH, Yin C, Mao HQ, Leong KW, Xu X, Goh CH, Ng ML, Yu H. Engineering microenvironment for expansion of sensitive anchorage-dependent mammalian cells. J Biotechnol 2005; 118:434-47. [PMID: 16026880 DOI: 10.1016/j.jbiotec.2005.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Revised: 05/02/2005] [Accepted: 05/12/2005] [Indexed: 01/07/2023]
Abstract
Tissue engineering involves ex vivo seeding of anchorage-dependent mammalian cells onto scaffolds, or transplanting cells in vivo. The cell expansion currently requires repeated cell detachment from solid substrata by enzymatic, chemical or mechanical means. The report here presents a high yield three-dimensional culture and harvest system circumventing the conventional detachment requirements. Cells mixed with dilute cationic collagen were microencapsulated within an ultra-thin shell of synthetic polymers. The cationic collagen could rapidly form a conformal layer of collagen fibers around cells to support cell proliferation and functions. The collagen could be readily removed from cells with a buffer rinse after harvesting from the fragile microcapsules. The cells harvested from this system demonstrate improved attachment, morphology and functions over conventionally cultured cells, upon binding to ligand-conjugated polymer surfaces. The harvested cells can be re-encapsulated and allowed to proliferate again, or used immediately in applications.
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Affiliation(s)
- Ser-Mien Chia
- Faculty of Medicine, National University of Singapore, Singapore
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29
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Abstract
The cell body has classically been considered the exclusive source of axonal proteins. However, significant evidence has accumulated recently to support the view that protein synthesis can occur in axons themselves, remote from the cell body. Indeed, local translation in axons may be integral to aspects of synaptogenesis, long-term facilitation, and memory storage in invertebrate axons, and for growth cone navigation in response to environmental stimuli in developing vertebrate axons. Here we review the evidence supporting mRNA translation in axons and discuss the potential roles that local protein synthesis may play during development and subsequent neuronal function. We advance the view that local translation provides a rapid supply of nascent proteins in restricted axonal compartments that can potentially underlie long-term responses to transient stimuli.
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Affiliation(s)
- Michael Piper
- Department of Anatomy, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
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30
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Beirowski B, Adalbert R, Wagner D, Grumme DS, Addicks K, Ribchester RR, Coleman MP. The progressive nature of Wallerian degeneration in wild-type and slow Wallerian degeneration (WldS) nerves. BMC Neurosci 2005; 6:6. [PMID: 15686598 PMCID: PMC549193 DOI: 10.1186/1471-2202-6-6] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Accepted: 02/01/2005] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The progressive nature of Wallerian degeneration has long been controversial. Conflicting reports that distal stumps of injured axons degenerate anterogradely, retrogradely, or simultaneously are based on statistical observations at discontinuous locations within the nerve, without observing any single axon at two distant points. As axon degeneration is asynchronous, there are clear advantages to longitudinal studies of individual degenerating axons. We recently validated the study of Wallerian degeneration using yellow fluorescent protein (YFP) in a small, representative population of axons, which greatly improves longitudinal imaging. Here, we apply this method to study the progressive nature of Wallerian degeneration in both wild-type and slow Wallerian degeneration (WldS) mutant mice. RESULTS In wild-type nerves, we directly observed partially fragmented axons (average 5.3%) among a majority of fully intact or degenerated axons 37-42 h after transection and 40-44 h after crush injury. Axons exist in this state only transiently, probably for less than one hour. Surprisingly, axons degenerated anterogradely after transection but retrogradely after a crush, but in both cases a sharp boundary separated intact and fragmented regions of individual axons, indicating that Wallerian degeneration progresses as a wave sequentially affecting adjacent regions of the axon. In contrast, most or all WldS axons were partially fragmented 15-25 days after nerve lesion, WldS axons degenerated anterogradely independent of lesion type, and signs of degeneration increased gradually along the nerve instead of abruptly. Furthermore, the first signs of degeneration were short constrictions, not complete breaks. CONCLUSIONS We conclude that Wallerian degeneration progresses rapidly along individual wild-type axons after a heterogeneous latent phase. The speed of progression and its ability to travel in either direction challenges earlier models in which clearance of trophic or regulatory factors by axonal transport triggers degeneration. WldS axons, once they finally degenerate, do so by a fundamentally different mechanism, indicated by differences in the rate, direction and abruptness of progression, and by different early morphological signs of degeneration. These observations suggest that WldS axons undergo a slow anterograde decay as axonal components are gradually depleted, and do not simply follow the degeneration pathway of wild-type axons at a slower rate.
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Affiliation(s)
- Bogdan Beirowski
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann Strasse 9, D-50931 Cologne, Germany
| | - Robert Adalbert
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
- Babraham Institute, Babraham, Cambridge CB2 4 AT, UK
| | - Diana Wagner
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
| | - Daniela S Grumme
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
| | - Klaus Addicks
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann Strasse 9, D-50931 Cologne, Germany
| | - Richard R Ribchester
- Division of Neuroscience, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - Michael P Coleman
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
- Babraham Institute, Babraham, Cambridge CB2 4 AT, UK
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Khandjian EW, Huot ME, Tremblay S, Davidovic L, Mazroui R, Bardoni B. Biochemical evidence for the association of fragile X mental retardation protein with brain polyribosomal ribonucleoparticles. Proc Natl Acad Sci U S A 2004; 101:13357-62. [PMID: 15329415 PMCID: PMC516571 DOI: 10.1073/pnas.0405398101] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fragile X syndrome is caused by the absence of the fragile X mental retardation protein (FMRP). This RNA-binding protein is widely expressed in human and mouse tissues, and it is particularly abundant in the brain because of its high expression in neurons, where it localizes in the cell body and in granules throughout dendrites. Although FMRP is thought to regulate trafficking of repressed mRNA complexes and to influence local protein synthesis in synapses, it is not known whether it has additional functions in the control of translation in the cell body. Here, we have used recently developed approaches to investigate whether FMRP is associated with the translation apparatus. We demonstrate that, in the brain, FMRP is present in actively translating polyribosomes, and we show that this association is acutely sensitive to the type of detergent required to release polyribosomes from membranous structures. In addition, proteomic analyses of purified brain polyribosomes reveal the presence of several RNA-binding proteins that, similarly to FMRP, have been previously localized in neuronal granules. Our findings highlight the complex roles of FMRP both in actively translating polyribosomes and in repressed trafficking ribonucleoparticle granules.
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Affiliation(s)
- Edouard W Khandjian
- Unité de Recherche en Génétique Humaine et Moléculaire, Centre de Recherche Hôpital Saint-François d'Assise, Centre Hospitalier Universitaire de Québec, Québec, QC, Canada G1L 3L5.
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Atlas R, Behar L, Elliott E, Ginzburg I. The insulin-like growth factor mRNA binding-protein IMP-1 and the Ras-regulatory protein G3BP associate with tau mRNA and HuD protein in differentiated P19 neuronal cells. J Neurochem 2004; 89:613-26. [PMID: 15086518 DOI: 10.1111/j.1471-4159.2004.02371.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tau mRNA is axonally localized mRNA that is found in developing neurons and targeted by an axonal localization signal (ALS) that is located in the 3'UTR of the message. The tau mRNA is trafficked in an RNA-protein complex (RNP) from the neuronal cell body to the distal parts of the axon, reaching as far as the growth cone. This movement is microtubule-dependent and is observed as granules that contain tau mRNA and additional proteins. A major protein contained in the granule is HuD, an Elav protein family member, which has an identified mRNA binding site on the tau 3'UTR and stabilizes the tau message and several axonally targeted mRNAs. Using GST-HuD fusion protein as bait, we have identified four proteins contained within the tau RNP, in differentiated P19 neuronal cells. In this work, we studied two of the identified proteins, i.e. IGF-II mRNA binding protein 1 (IMP-1), the orthologue of chick beta-actin binding protein-ZBP1, and RAS-GAP SH3 domain binding protein (G3BP). We show that IMP-1 associates with HuD and G3BP-1 proteins in an RNA-dependent manner and binds directly to tau mRNA. We also show an RNA-dependent association between G3BP-1 and HuD proteins. These associations are investigated in relation to the neuronal differentiation of P19 cells.
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Affiliation(s)
- Roee Atlas
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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Abstract
Axons from the retina traverse different molecular territories as they navigate to the tectum. A single territory might span only a few cell diameters and harbour multiple guidance cues, many of which are beginning to be characterized. Also present in the pathway are 'modulators' that influence a growth cone's response to a coincident signal but do not guide growth directly. An emerging principle is that the growth cone, itself, changes molecularly as it journeys through the visual pathway. Growing retinal axons contain mRNAs, ubiquitinating and apoptotic enzymes, translation and degradation machinery. Guidance cues can trigger rapid and local synthesis, degradation and endocytosis of proteins, providing a fast and flexible way for growth cones to respond to cues in their microenvironment and to alter their responsiveness. The data raise the idea that the localized synthesis and downregulation of proteins might help to steer retinal axon growth and, further, might contribute to the changing character of a growth cone as it ages.
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Ma Y, Shakiryanova D, Vardya I, Popov SV. Quantitative Analysis of Microtubule Transport in Growing Nerve Processes. Curr Biol 2004; 14:725-30. [PMID: 15084289 DOI: 10.1016/j.cub.2004.03.061] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2003] [Revised: 01/19/2004] [Accepted: 03/02/2004] [Indexed: 11/24/2022]
Abstract
In neurons, tubulin is synthesized primarily in the cell body, whereas the molecular machinery for neurite extension and elaboration of microtubule (MT) array is localized to the growth cone region. This unique functional and biochemical compartmentalization of neuronal cells requires transport mechanisms for the delivery of newly synthesized tubulin and other cytoplasmic components from the cell body to the growing axon. According to the polymer transport model, tubulin is transported along the axon as a polymer. Because the majority of axonal MTs are stationary at any given moment, it has been assumed that only a small fraction of MTs translocates along the axon by saltatory movement reminiscent of the fast axonal transport. Such intermittent "stop and go" MT transport has been difficult to detect or to exclude by using direct video microscopy methods. In this study, we measured the translocation of MT plus ends in the axonal shaft by expressing GFP-EB1 in Xenopus embryo neurons in culture. Formal quantitative analysis of MT assembly/disassembly indicated that none of the MTs in the axonal shaft were rapidly transported. Our results suggest that transport of axonal MTs is not required for delivery of newly synthesized tubulin to the growing nerve processes.
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Affiliation(s)
- Yitao Ma
- Department of Physiology and Biophysics, M/C 901, University of Illinois at Chicago, 835 South Wolcott Avenue, Chicago, IL 60612, USA
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Abstract
Neuromuscular junctions (NMJs) on fast and slow muscle fibers display different transmitter release characteristics that appear well adapted to the different patterns of nerve impulses that they transmit in vivo. Here, we ask whether the release properties of such NMJs, termed fast and slow, can be transformed by chronic nerve stimulation. In young adult rats, nerve impulse conduction in the sciatic nerve was blocked by TTX, and the nerve to the fast extensor digitorum longus (EDL) or the slow soleus (SOL) muscle stimulated directly below the block with slow (20 Hz for 10 sec every 30 sec) or fast (150 Hz for 1 sec every 60 sec) stimulus patterns, respectively. After 3-4 weeks, originally fast EDL-NMJs and slow SOL-NMJs had become almost fully transformed to slow and fast NMJs, respectively, with respect to maintenance of transmitter release during tonic 20 Hz stimulation in vitro and ratio of quantal content to vesicle pool size. TTX block alone had no such transforming effect. Vesicle recycle time was unaffected by the stimulation, whereas initial quantal content and vesicle pool size were reduced (by 49% and 57% in EDL and 33% and 67% in SOL). Muscle fiber diameter also declined (by 49% in EDL and 33% in SOL vs 46% in unstimulated SOL; unstimulated EDL was not examined). We conclude that fast and slow NMJs display marked plasticity by being able to adapt important release characteristics to the impulse patterns imposed on them.
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Durand S, Fromy B, Tartas M, Jardel A, Saumet JL, Abraham P. Prolonged aspirin inhibition of anodal vasodilation is not due to the trafficking delay of neural mediators. Am J Physiol Regul Integr Comp Physiol 2003; 285:R155-61. [PMID: 12793996 DOI: 10.1152/ajpregu.00742.2002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We previously reported that forearm vasodilation to a delivered all-at-once over 5 min or a 1-min repeated monopolar anodal 0.10-mA current application is aspirin sensitive and that a single high-dose aspirin exerts a long-lived effect in the former case. We hypothesized that 1) in the latter case, the effect of aspirin would also be long lived and 2) the time required to resupply nerve endings with unblocked cyclooxygenase through axonal transport could explain this phenomenon. We studied the time course for the recovery of vasodilation to repeated current application after placebo or 1-g aspirin treatment. We then searched for a difference at a proximal vs. distal site in the recovery of the response. Aspirin abolished current-induced vasodilation at 2 h, 10 h, and 3 days, with a progressive recovery thereafter, but no difference between distal and proximal site was observed for the recovery of the response. This suggests that, although neural cyclooxygenase could participate in the response, the time course of aspirin inhibition of current-induced cutaneous vasodilation is not due to the time required through neural transport to resupply nerve endings with unblocked proteins.
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Affiliation(s)
- S Durand
- Laboratoire de Physiologie et Explorations Vasculaires, Centre Hospitalier Universitaire, 49033 Angers cedex, France
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37
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Abstract
Ramon y Cajal proclaimed in 1928 that "once development was ended, the founts of growth and regeneration of the axons and dendrites dried up irrevocably. In the adult centers the nerve paths are something fixed, ended and immutable. Everything must die, nothing may be regenerated. It is for the science of the future to change, if possible, this harsh decree." (Ramon y Cajal, 1928). In large part, despite the extensive knowledge gained since then, the latter directive has not yet been achieved by 'modern' science. Although we know now that Ramon y Cajal's observation on CNS plasticity is largely true (for lower brain and primary cortical structures), there are mechanisms for recovery from CNS injury. These mechanisms, however, may contribute to the vulnerability to neurodegenerative disease. They may also be exploited therapeutically to help alleviate the suffering from neurodegenerative conditions.
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Affiliation(s)
- Bruce Teter
- Department of Medicine, University of California Los Angeles, California and Veteran's Affairs-Greater Los Angeles Healthcare System, Sepulveda, California 91343, USA
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