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Mousele C, Holden D, Gnanapavan S. Neurofilaments in neurologic disease. Adv Clin Chem 2024; 123:65-128. [PMID: 39181624 DOI: 10.1016/bs.acc.2024.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Neurofilaments (NFs), major cytoskeletal constituents of neurons, have emerged as universal biomarkers of neuronal injury. Neuroaxonal damage underlies permanent disability in various neurological conditions. It is crucial to accurately quantify and longitudinally monitor this damage to evaluate disease progression, evaluate treatment effectiveness, contribute to novel treatment development, and offer prognostic insights. Neurofilaments show promise for this purpose, as their levels increase with neuroaxonal damage in both cerebrospinal fluid and blood, independent of specific causal pathways. New assays with high sensitivity allow reliable measurement of neurofilaments in body fluids and open avenues to investigate their role in neurological disorders. This book chapter will delve into the evolving landscape of neurofilaments, starting with their structure and cellular functions within neurons. It will then provide a comprehensive overview of their broad clinical value as biomarkers in diseases affecting the central or peripheral nervous system.
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Ding EA, Kumar S. Neurofilament Biophysics: From Structure to Biomechanics. Mol Biol Cell 2024; 35:re1. [PMID: 38598299 PMCID: PMC11151108 DOI: 10.1091/mbc.e23-11-0438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/25/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024] Open
Abstract
Neurofilaments (NFs) are multisubunit, neuron-specific intermediate filaments consisting of a 10-nm diameter filament "core" surrounded by a layer of long intrinsically disordered protein (IDP) "tails." NFs are thought to regulate axonal caliber during development and then stabilize the mature axon, with NF subunit misregulation, mutation, and aggregation featuring prominently in multiple neurological diseases. The field's understanding of NF structure, mechanics, and function has been deeply informed by a rich variety of biochemical, cell biological, and mouse genetic studies spanning more than four decades. These studies have contributed much to our collective understanding of NF function in axonal physiology and disease. In recent years, however, there has been a resurgence of interest in NF subunit proteins in two new contexts: as potential blood- and cerebrospinal fluid-based biomarkers of neuronal damage, and as model IDPs with intriguing properties. Here, we review established principles and more recent discoveries in NF structure and function. Where possible, we place these findings in the context of biophysics of NF assembly, interaction, and contributions to axonal mechanics.
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Affiliation(s)
- Erika A. Ding
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Sanjay Kumar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158
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LoBue C, Stopschinski BE, Calveras NS, Douglas PM, Huebinger R, Cullum CM, Hart J, Gonzales MM. Blood Markers in Relation to a History of Traumatic Brain Injury Across Stages of Cognitive Impairment in a Diverse Cohort. J Alzheimers Dis 2024; 97:345-358. [PMID: 38143366 PMCID: PMC10947497 DOI: 10.3233/jad-231027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2023]
Abstract
BACKGROUND Traumatic brain injury (TBI) has been linked to multiple pathophysiological processes that could increase risk for Alzheimer's disease and related dementias (ADRD). However, the impact of prior TBI on blood biomarkers for ADRD remains unknown. OBJECTIVE Using cross-sectional data, we assessed whether a history of TBI influences serum biomarkers in a diverse cohort (approximately 50% Hispanic) with normal cognition, mild cognitive impairment, or dementia. METHODS Levels of glial fibrillary acidic protein (GFAP), neurofilament light (NFL), total tau (T-tau), and ubiquitin carboxy-terminal hydrolase-L1 (UCHL1) were measured for participants across the cognitive spectrum. Participants were categorized based on presence and absence of a history of TBI with loss of consciousness, and study samples were derived through case-control matching. Multivariable general linear models compared concentrations of biomarkers in relation to a history of TBI and smoothing splines modelled biomarkers non-linearly in the cognitively impaired groups as a function of time since symptom onset. RESULTS Each biomarker was higher across stages of cognitive impairment, characterized by clinical diagnosis and Mini-Mental State Examination performance, but these associations were not influenced by a history of TBI. However, modelling biomarkers in relation to duration of cognitive symptoms for ADRD showed differences by history of TBI, with only GFAP and UCHL1 being elevated. CONCLUSIONS Serum GFAP, NFL, T-tau, and UCHL1 were higher across stages of cognitive impairment in this diverse clinical cohort, regardless of TBI history, though longitudinal investigation of the timing, order, and trajectory of the biomarkers in relation to prior TBI is warranted.
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Affiliation(s)
- Christian LoBue
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas,TX
- Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX
| | - Barbara E. Stopschinski
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX
- Center for Alzheimer’s and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, TX
| | - Nil Saez Calveras
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX
- Center for Alzheimer’s and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, TX
| | - Peter M. Douglas
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ryan Huebinger
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX
| | - C. Munro Cullum
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas,TX
- Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX
| | - John Hart
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas,TX
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Mitzi M. Gonzales
- Department of Neurology, Cedars Sinai Medical Center, Los Angeles, CA
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, San Antonio, TX
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Kotaich F, Caillol D, Bomont P. Neurofilaments in health and Charcot-Marie-Tooth disease. Front Cell Dev Biol 2023; 11:1275155. [PMID: 38164457 PMCID: PMC10758125 DOI: 10.3389/fcell.2023.1275155] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/02/2023] [Indexed: 01/03/2024] Open
Abstract
Neurofilaments (NFs) are the most abundant component of mature neurons, that interconnect with actin and microtubules to form the cytoskeleton. Specifically expressed in the nervous system, NFs present the particularity within the Intermediate Filament family of being formed by four subunits, the neurofilament light (NF-L), medium (NF-M), heavy (NF-H) proteins and α-internexin or peripherin. Here, we review the current knowledge on NF proteins and neurofilaments, from their domain structures and their model of assembly to the dynamics of their transport and degradation along the axon. The formation of the filament and its behaviour are regulated by various determinants, including post-transcriptional (miRNA and RBP proteins) and post-translational (phosphorylation and ubiquitination) modifiers. Altogether, the complex set of modifications enable the neuron to establish a stable but elastic NF array constituting the structural scaffold of the axon, while permitting the local expression of NF proteins and providing the dynamics necessary to fulfil local demands and respond to stimuli and injury. Thus, in addition to their roles in mechano-resistance, radial axonal outgrowth and nerve conduction, NFs control microtubule dynamics, organelle distribution and neurotransmission at the synapse. We discuss how the studies of neurodegenerative diseases with NF aggregation shed light on the biology of NFs. In particular, the NEFL and NEFH genes are mutated in Charcot-Marie-Tooth (CMT) disease, the most common inherited neurological disorder of the peripheral nervous system. The clinical features of the CMT forms (axonal CMT2E, CMT2CC; demyelinating CMT1F; intermediate I-CMT) with symptoms affecting the central nervous system (CNS) will allow us to further investigate the physiological roles of NFs in the brain. Thus, NF-CMT mouse models exhibit various degrees of sensory-motor deficits associated with CNS symptoms. Cellular systems brought findings regarding the dominant effect of NF-L mutants on NF aggregation and transport, although these have been recently challenged. Neurofilament detection without NF-L in recessive CMT is puzzling, calling for a re-examination of the current model in which NF-L is indispensable for NF assembly. Overall, we discuss how the fundamental and translational fields are feeding each-other to increase but also challenge our knowledge of NF biology, and to develop therapeutic avenues for CMT and neurodegenerative diseases with NF aggregation.
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Affiliation(s)
| | | | - Pascale Bomont
- ERC team, NeuroMyoGene Institute-Pathophysiology and Genetics of Neuron and Muscle, Inserm U1315, CNRS UMR5261, University of Lyon 1, Lyon, France
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Krieg JL, Leonard AV, Turner RJ, Corrigan F. Identifying the Phenotypes of Diffuse Axonal Injury Following Traumatic Brain Injury. Brain Sci 2023; 13:1607. [PMID: 38002566 PMCID: PMC10670443 DOI: 10.3390/brainsci13111607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023] Open
Abstract
Diffuse axonal injury (DAI) is a significant feature of traumatic brain injury (TBI) across all injury severities and is driven by the primary mechanical insult and secondary biochemical injury phases. Axons comprise an outer cell membrane, the axolemma which is anchored to the cytoskeletal network with spectrin tetramers and actin rings. Neurofilaments act as space-filling structural polymers that surround the central core of microtubules, which facilitate axonal transport. TBI has differential effects on these cytoskeletal components, with axons in the same white matter tract showing a range of different cytoskeletal and axolemma alterations with different patterns of temporal evolution. These require different antibodies for detection in post-mortem tissue. Here, a comprehensive discussion of the evolution of axonal injury within different cytoskeletal elements is provided, alongside the most appropriate methods of detection and their temporal profiles. Accumulation of amyloid precursor protein (APP) as a result of disruption of axonal transport due to microtubule failure remains the most sensitive marker of axonal injury, both acutely and chronically. However, a subset of injured axons demonstrate different pathology, which cannot be detected via APP immunoreactivity, including degradation of spectrin and alterations in neurofilaments. Furthermore, recent work has highlighted the node of Ranvier and the axon initial segment as particularly vulnerable sites to axonal injury, with loss of sodium channels persisting beyond the acute phase post-injury in axons without APP pathology. Given the heterogenous response of axons to TBI, further characterization is required in the chronic phase to understand how axonal injury evolves temporally, which may help inform pharmacological interventions.
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Affiliation(s)
| | | | | | - Frances Corrigan
- Translational Neuropathology Laboratory, School of Biomedicine, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide 5000, Australia; (J.L.K.)
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Uchida A, Peng J, Brown A. Regulation of neurofilament length and transport by a dynamic cycle of phospho-dependent polymer severing and annealing. Mol Biol Cell 2023; 34:ar68. [PMID: 36989035 PMCID: PMC10295484 DOI: 10.1091/mbc.e23-01-0024] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023] Open
Abstract
Neurofilaments are cargoes of axonal transport which are unique among known intracellular cargoes in that they are long, flexible protein polymers. These polymers are transported into axons, where they accumulate in large numbers to drive the expansion of axon caliber, which is an important determinant of axonal conduction velocity. We reported previously that neurofilaments can be lengthened by joining ends, called end-to-end annealing, and that they can be shortened by severing. Here, we show that neurofilament annealing and severing are robust and quantifiable phenomena in cultured neurons that act antagonistically to regulate neurofilament length. We show that this in turn regulates neurofilament transport and that severing is regulated by N-terminal phosphorylation of the neurofilament subunit proteins. We propose that focal destabilization of intermediate filaments by site-directed phosphorylation may be a general enzymatic mechanism for severing these cytoskeletal polymers, providing a mechanism to regulate the transport and accumulation of neurofilaments in axons.
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Affiliation(s)
- Atsuko Uchida
- Department of Neuroscience, Ohio State University, Columbus, OH 43210
| | - Juan Peng
- Center for Biostatistics and Department of Biomedical Informatics, Ohio State University, Columbus, OH 43210
| | - Anthony Brown
- Department of Neuroscience, Ohio State University, Columbus, OH 43210
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Chen X, Fang L, Peng F, Wang Y, Dai Z, Wang J, Shu Y, Qiu W. Serum neurofilament light chain is associated with disturbed limbic-based functional connectivity in patients with anti-NMDAR encephalitis. J Neurochem 2023; 164:210-225. [PMID: 36184969 DOI: 10.1111/jnc.15700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/20/2022] [Accepted: 09/22/2022] [Indexed: 01/31/2023]
Abstract
Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis shows a predilection for affecting the limbic system, but structural MRI in most patients is usually unremarkable. However, the functional connectivity reorganization of limbic nodes remains unknown. Serum neurofilament light chains (sNfL) are clinically linked with the disease severity and neurological disability of anti-NMDAR encephalitis. However, the relationship between sNfL and limbic-based functional architecture has not been explored. We consecutively recruited 20 convalescent patients with anti-NMDAR encephalitis and 24 healthy controls from March 2018 to March 2021. Resting-state functional MRI metrics, including fractional amplitude of low-frequency fluctuation (fALFF), regional homogeneity (ReHo), and atlas-based seed functional connectivity, were analyzed to investigate regional activities and functional connectivity alterations. Correlation analysis among functional connectivity, sNfL, Mini-Mental State Examination (MMSE), and Montreal cognitive assessment outcomes were explored in patients. Compared with those of healthy controls, the fALFF and ReHo were consistently increased in regions of the posterior default mode network (DMN) hub, mainly the bilateral supramarginal gyrus and precuneus, in patients with anti-NMDAR encephalitis (FWE-corrected p < 0.05). Patients demonstrated disturbed functional organization characterized by reduced connectivity of the posterior DMN hub with the sensorimotor cortex and hypoconnectivity of the parahippocampal gyrus (PHG) with the right fusiform gyrus but extensively enhanced thalamocortical connectivity (FWE-corrected p < 0.05). Furthermore, convalescent sNfL showed a positive correlation with enhanced thalamocortical connectivity (r = 0.4659, p = 0.0384). Onset sNfL with an independent linear correlation to convalescent MMSE performance (B coefficient, -0.013, 95% CI, -0.025 ~ -0.002, p = 0.0260) was positively correlated with intra-DMN connectivity (r = 0.8969, p < 0.0001) and limbic-sensory connectivity (r = 0.4866, p = 0.0346 for hippocampus seed and r = 0.5218, p = 0.0220 for PHG seed). Patients with anti-NMDAR encephalitis demonstrated disturbed functional organization with substantial thalamocortical hyperconnectivity, that was positively correlated with convalescent sNfL. Onset sNfL showed a positive correlation with intra-DMN connectivity and limbic-sensory connectivity.
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Affiliation(s)
- Xiaodong Chen
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China.,Department of Neurology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Ling Fang
- Department of Radiology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Fuhua Peng
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yuge Wang
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhengjia Dai
- Department of Psychology, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jinhui Wang
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou, China
| | - Yaqing Shu
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wei Qiu
- Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
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Schwann cell functions in peripheral nerve development and repair. Neurobiol Dis 2023; 176:105952. [PMID: 36493976 DOI: 10.1016/j.nbd.2022.105952] [Citation(s) in RCA: 47] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/23/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
The glial cell of the peripheral nervous system (PNS), the Schwann cell (SC), counts among the most multifaceted cells of the body. During development, SCs secure neuronal survival and participate in axonal path finding. Simultaneously, they orchestrate the architectural set up of the developing nerves, including the blood vessels and the endo-, peri- and epineurial layers. Perinatally, in rodents, SCs radially sort and subsequently myelinate individual axons larger than 1 μm in diameter, while small calibre axons become organised in non-myelinating Remak bundles. SCs have a vital role in maintaining axonal health throughout life and several specialized SC types perform essential functions at specific locations, such as terminal SC at the neuromuscular junction (NMJ) or SC within cutaneous sensory end organs. In addition, neural crest derived satellite glia maintain a tight communication with the soma of sensory, sympathetic, and parasympathetic neurons and neural crest derivatives are furthermore an indispensable part of the enteric nervous system. The remarkable plasticity of SCs becomes evident in the context of a nerve injury, where SC transdifferentiate into intriguing repair cells, which orchestrate a regenerative response that promotes nerve repair. Indeed, the multiple adaptations of SCs are captivating, but remain often ill-resolved on the molecular level. Here, we summarize and discuss the knowns and unknowns of the vast array of functions that this single cell type can cover in peripheral nervous system development, maintenance, and repair.
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Tyagi M, Kapoor I, Mahajan C, Gupta N, Prabhakar H. Brain Biomarkers in Patients with COVID-19 and Neurological Manifestations: A Narrative Review. JOURNAL OF NEUROANAESTHESIOLOGY AND CRITICAL CARE 2022. [DOI: 10.1055/s-0042-1744395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AbstractAcute hyperinflammatory response (cytokine storm) and immunosuppression are responsible for critical illness in patients infected with coronavirus disease 2019 (COVID-19). It is a serious public health crisis that has affected millions of people worldwide. The main clinical manifestations are mostly by respiratory tract involvement and have been extensively researched. Increasing numbers of evidence from emerging studies point out the possibility of neurological involvement by COVID-19 highlighting the need for developing technology to diagnose, manage, and treat brain injury in such patients. Here, we aimed to discuss the rationale for the use of an emerging spectrum of blood biomarkers to guide future diagnostic strategies to mitigate brain injury-associated morbidity and mortality risks in COVID-19 patients, their use in clinical practice, and prediction of neurological outcomes.
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Affiliation(s)
- Mayank Tyagi
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Indu Kapoor
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Charu Mahajan
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Nidhi Gupta
- Department of Neuroanesthesia, Indraprastha Apollo Hospital, New Delhi, India
| | - Hemanshu Prabhakar
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
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Biernacki T, Kokas Z, Sandi D, Füvesi J, Fricska-Nagy Z, Faragó P, Kincses TZ, Klivényi P, Bencsik K, Vécsei L. Emerging Biomarkers of Multiple Sclerosis in the Blood and the CSF: A Focus on Neurofilaments and Therapeutic Considerations. Int J Mol Sci 2022; 23:ijms23063383. [PMID: 35328802 PMCID: PMC8951485 DOI: 10.3390/ijms23063383] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/12/2022] [Accepted: 03/17/2022] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Multiple Sclerosis (MS) is the most common immune-mediated chronic neurodegenerative disease of the central nervous system (CNS) affecting young people. This is due to the permanent disability, cognitive impairment, and the enormous detrimental impact MS can exert on a patient's health-related quality of life. It is of great importance to recognise it in time and commence adequate treatment at an early stage. The currently used disease-modifying therapies (DMT) aim to reduce disease activity and thus halt disability development, which in current clinical practice are monitored by clinical and imaging parameters but not by biomarkers found in blood and/or the cerebrospinal fluid (CSF). Both clinical and radiological measures routinely used to monitor disease activity lack information on the fundamental pathophysiological features and mechanisms of MS. Furthermore, they lag behind the disease process itself. By the time a clinical relapse becomes evident or a new lesion appears on the MRI scan, potentially irreversible damage has already occurred in the CNS. In recent years, several biomarkers that previously have been linked to other neurological and immunological diseases have received increased attention in MS. Additionally, other novel, potential biomarkers with prognostic and diagnostic properties have been detected in the CSF and blood of MS patients. AREAS COVERED In this review, we summarise the most up-to-date knowledge and research conducted on the already known and most promising new biomarker candidates found in the CSF and blood of MS patients. DISCUSSION the current diagnostic criteria of MS relies on three pillars: MRI imaging, clinical events, and the presence of oligoclonal bands in the CSF (which was reinstated into the diagnostic criteria by the most recent revision). Even though the most recent McDonald criteria made the diagnosis of MS faster than the prior iteration, it is still not an infallible diagnostic toolset, especially at the very early stage of the clinically isolated syndrome. Together with the gold standard MRI and clinical measures, ancillary blood and CSF biomarkers may not just improve diagnostic accuracy and speed but very well may become agents to monitor therapeutic efficacy and make even more personalised treatment in MS a reality in the near future. The major disadvantage of these biomarkers in the past has been the need to obtain CSF to measure them. However, the recent advances in extremely sensitive immunoassays made their measurement possible from peripheral blood even when present only in minuscule concentrations. This should mark the beginning of a new biomarker research and utilisation era in MS.
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Affiliation(s)
- Tamás Biernacki
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Zsófia Kokas
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Dániel Sandi
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Judit Füvesi
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Zsanett Fricska-Nagy
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Péter Faragó
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Tamás Zsigmond Kincses
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
- Albert Szent-Györgyi Clinical Centre, Department of Radiology, Albert Szent-Györgyi Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary
| | - Péter Klivényi
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - Krisztina Bencsik
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
| | - László Vécsei
- Albert Szent-Györgyi Clinical Centre, Department of Neurology, Faculty of General Medicine, University of Szeged, 6725 Szeged, Hungary; (T.B.); (Z.K.); (D.S.); (J.F.); (Z.F.-N.); (P.F.); (T.Z.K.); (P.K.); (K.B.)
- MTA-SZTE Neuroscience Research Group, University of Szeged, 6725 Szeged, Hungary
- Correspondence: ; Tel.: +36-62-545-356; Fax: +36-62-545-597
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Studying Neuronal Biology Using Spinning Disc Confocal Microscopy. Methods Mol Biol 2021. [PMID: 34028722 DOI: 10.1007/978-1-0716-1402-0_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Cytoskeletal integrity is essential for neuronal complexity and functionality. Certain inherited neurological diseases are associated with mutated genes that directly or indirectly compromise cytoskeletal stability. While the large size and complexity of the neurons grown in culture poses certain challenges for imaging, live-cell imaging is an excellent approach to determine the morphological consequences of such mutants. This protocol details the use of spinning disk confocal microscopy and image analysis tools to evaluate branching and neurite length of healthy iPSC-derived glutamatergic neurons that express specific fluorescent proteins. The protocols can be adapted to neuronal cell lines of choice by the investigator.
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Parcerisas A, Ortega-Gascó A, Hernaiz-Llorens M, Odena MA, Ulloa F, de Oliveira E, Bosch M, Pujadas L, Soriano E. New Partners Identified by Mass Spectrometry Assay Reveal Functions of NCAM2 in Neural Cytoskeleton Organization. Int J Mol Sci 2021; 22:ijms22147404. [PMID: 34299022 PMCID: PMC8304497 DOI: 10.3390/ijms22147404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 02/06/2023] Open
Abstract
Neuronal cell adhesion molecule 2 (NCAM2) is a membrane protein with an important role in the morphological development of neurons. In the cortex and the hippocampus, NCAM2 is essential for proper neuronal differentiation, dendritic and axonal outgrowth and synapse formation. However, little is known about NCAM2 functional mechanisms and its interactive partners during brain development. Here we used mass spectrometry to study the molecular interactome of NCAM2 in the second postnatal week of the mouse cerebral cortex. We found that NCAM2 interacts with >100 proteins involved in numerous processes, including neuronal morphogenesis and synaptogenesis. We validated the most relevant interactors, including Neurofilaments (NEFs), Microtubule-associated protein 2 (MAP2), Calcium/calmodulin kinase II alpha (CaMKIIα), Actin and Nogo. An in silico analysis of the cytosolic tail of the NCAM2.1 isoform revealed specific phosphorylation site motifs with a putative affinity for some of these interactors. Our results expand the knowledge of NCAM2 interactome and confirm the key role of NCAM2 in cytoskeleton organization, neuronal morphogenesis and synaptogenesis. These findings are of interest in explaining the phenotypes observed in different pathologies with alterations in the NCAM2 gene.
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Affiliation(s)
- Antoni Parcerisas
- Department of Cell Biology, Physiology and Immunology, University of Barcelona and Institute of Neurosciences, 08028 Barcelona, Spain; (A.O.-G.); (M.H.-L.); (F.U.); (L.P.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Basic Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Spain;
- Correspondence: (A.P.); (E.S.)
| | - Alba Ortega-Gascó
- Department of Cell Biology, Physiology and Immunology, University of Barcelona and Institute of Neurosciences, 08028 Barcelona, Spain; (A.O.-G.); (M.H.-L.); (F.U.); (L.P.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Marc Hernaiz-Llorens
- Department of Cell Biology, Physiology and Immunology, University of Barcelona and Institute of Neurosciences, 08028 Barcelona, Spain; (A.O.-G.); (M.H.-L.); (F.U.); (L.P.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Maria Antonia Odena
- Plataforma de Proteòmica, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain; (M.A.O.); (E.d.O.)
| | - Fausto Ulloa
- Department of Cell Biology, Physiology and Immunology, University of Barcelona and Institute of Neurosciences, 08028 Barcelona, Spain; (A.O.-G.); (M.H.-L.); (F.U.); (L.P.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Eliandre de Oliveira
- Plataforma de Proteòmica, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain; (M.A.O.); (E.d.O.)
| | - Miquel Bosch
- Department of Basic Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Spain;
| | - Lluís Pujadas
- Department of Cell Biology, Physiology and Immunology, University of Barcelona and Institute of Neurosciences, 08028 Barcelona, Spain; (A.O.-G.); (M.H.-L.); (F.U.); (L.P.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Eduardo Soriano
- Department of Cell Biology, Physiology and Immunology, University of Barcelona and Institute of Neurosciences, 08028 Barcelona, Spain; (A.O.-G.); (M.H.-L.); (F.U.); (L.P.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Correspondence: (A.P.); (E.S.)
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13
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Jia Z, Li Y. A possible mechanism for neurofilament slowing down in myelinated axon: Phosphorylation-induced variation of NF kinetics. PLoS One 2021; 16:e0247656. [PMID: 33711034 PMCID: PMC7954336 DOI: 10.1371/journal.pone.0247656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 02/10/2021] [Indexed: 11/18/2022] Open
Abstract
Neurofilaments(NFs) are the most abundant intermediate filaments that make up the inner volume of axon, with possible phosphorylation on their side arms, and their slow axonal transport by molecular motors along microtubule tracks in a “stop-and-go” manner with rapid, intermittent and bidirectional motion. The kinetics of NFs and morphology of axon are dramatically different between myelinate internode and unmyelinated node of Ranvier. The NFs in the node transport as 7.6 times faster as in the internode, and the distribution of NFs population in the internode is 7.6 folds as much as in the node of Ranvier. We hypothesize that the phosphorylation of NFs could reduce the on-track rate and slow down their transport velocity in the internode. By modifying the ‘6-state’ model with (a) an extra phosphorylation kinetics to each six state and (b) construction a new ‘8-state’ model in which NFs at off-track can be phosphorylated and have smaller on-track rate, our model and simulation demonstrate that the phosphorylation-induced decrease of on-track rate could slow down the NFs average velocity and increase the axonal caliber. The degree of phosphorylation may indicate the extent of velocity reduction. The Continuity equation used in our paper predicts that the ratio of NFs population is inverse proportional to the ratios of average velocity of NFs between node of Ranvier and internode. We speculate that the myelination of axon could increase the level of phosphorylation of NF side arms, and decrease the possibility of NFs to get on-track of microtubules, therefore slow down their transport velocity. In summary, our work provides a potential mechanism for understanding the phosphorylation kinetics of NFs in regulating their transport and morphology of axon in myelinated axons, and the different kinetics of NFs between node and internode.
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Affiliation(s)
- Zelin Jia
- School of Systems Science, Beijing Normal University, Beijing, China
| | - Yinyun Li
- School of Systems Science, Beijing Normal University, Beijing, China
- * E-mail:
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14
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Bomont P. The dazzling rise of neurofilaments: Physiological functions and roles as biomarkers. Curr Opin Cell Biol 2021; 68:181-191. [PMID: 33454158 DOI: 10.1016/j.ceb.2020.10.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 12/15/2022]
Abstract
In the last two years, neurofilaments (NFs) have become one of the most blazing topics in clinical neuroscience. NFs are major cytoskeletal constituents of neurons, can be detected in body fluids, and have recently emerged as universal biomarkers of neuronal injury and neurological diseases. This review will examine the evolving landscape of NFs, from their specific cellular functions within neurons to their broad clinical value as biomarkers. Particular attention will be given to the dynamic nature of the NF network and its novel roles in microtubule regulation, neurotransmission, and nanomedicine. Building from the initial evidence of causative mutations in NF genes in Charcot-Marie-Tooth diseases, the latest advances at the frontiers of basic and clinical sciences have expanded the scope and relevance of NFs for human health remarkably and have poised to fuel innovation in cell biology and neuroscience.
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Affiliation(s)
- Pascale Bomont
- ERC team, INMG, INSERM U1217, CNRS UMR5310, University of Lyon 1, University of Lyon, Lyon, France.
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15
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Gafson AR, Barthélemy NR, Bomont P, Carare RO, Durham HD, Julien JP, Kuhle J, Leppert D, Nixon RA, Weller RO, Zetterberg H, Matthews PM. Neurofilaments: neurobiological foundations for biomarker applications. Brain 2020; 143:1975-1998. [PMID: 32408345 DOI: 10.1093/brain/awaa098] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/20/2019] [Accepted: 01/20/2020] [Indexed: 12/11/2022] Open
Abstract
Interest in neurofilaments has risen sharply in recent years with recognition of their potential as biomarkers of brain injury or neurodegeneration in CSF and blood. This is in the context of a growing appreciation for the complexity of the neurobiology of neurofilaments, new recognition of specialized roles for neurofilaments in synapses and a developing understanding of mechanisms responsible for their turnover. Here we will review the neurobiology of neurofilament proteins, describing current understanding of their structure and function, including recently discovered evidence for their roles in synapses. We will explore emerging understanding of the mechanisms of neurofilament degradation and clearance and review new methods for future elucidation of the kinetics of their turnover in humans. Primary roles of neurofilaments in the pathogenesis of human diseases will be described. With this background, we then will review critically evidence supporting use of neurofilament concentration measures as biomarkers of neuronal injury or degeneration. Finally, we will reflect on major challenges for studies of the neurobiology of intermediate filaments with specific attention to identifying what needs to be learned for more precise use and confident interpretation of neurofilament measures as biomarkers of neurodegeneration.
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Affiliation(s)
- Arie R Gafson
- Department of Brain Sciences, Imperial College, London, UK
| | - Nicolas R Barthélemy
- Department of Neurology, Washington University School of Medicine, St Louis, MO, USA
| | - Pascale Bomont
- ATIP-Avenir team, INM, INSERM, Montpellier University, Montpellier, France
| | - Roxana O Carare
- Clinical Neurosciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Heather D Durham
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Jean-Pierre Julien
- Department of Psychiatry and Neuroscience, Laval University, Quebec, Canada.,CERVO Brain Research Center, 2601 Chemin de la Canardière, Québec, QC, G1J 2G3, Canada
| | - Jens Kuhle
- Neurologic Clinic and Policlinic, Departments of Medicine, Biomedicine and Clinical Research, University Hospital Basel, University of Basel, Basel, Switzerland
| | - David Leppert
- Neurologic Clinic and Policlinic, Departments of Medicine, Biomedicine and Clinical Research, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, 10962, USA.,Departments of Psychiatry, New York University School of Medicine, New York, NY, 10016, USA.,Neuroscience Institute, New York University School of Medicine, New York, NY, 10016, USA.,Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA
| | - Roy O Weller
- Clinical Neurosciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Henrik Zetterberg
- University College London Queen Square Institute of Neurology, London, UK.,UK Dementia Research Institute at University College London, London, UK.,Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.,Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Paul M Matthews
- Department of Brain Sciences, Imperial College, London, UK.,UK Dementia Research Institute at Imperial College, London
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16
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Serum neurofilament light chain levels are associated with white matter integrity in autosomal dominant Alzheimer's disease. Neurobiol Dis 2020; 142:104960. [PMID: 32522711 PMCID: PMC7363568 DOI: 10.1016/j.nbd.2020.104960] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/03/2020] [Accepted: 06/04/2020] [Indexed: 12/12/2022] Open
Abstract
Neurofilament light chain (NfL) is a protein that is selectively expressed in neurons. Increased levels of NfL measured in either cerebrospinal fluid or blood is thought to be a biomarker of neuronal damage in neurodegenerative diseases. However, there have been limited investigations relating NfL to the concurrent measures of white matter (WM) decline that it should reflect. White matter damage is a common feature of Alzheimer's disease. We hypothesized that serum levels of NfL would associate with WM lesion volume and diffusion tensor imaging (DTI) metrics cross-sectionally in 117 autosomal dominant mutation carriers (MC) compared to 84 non-carrier (NC) familial controls as well as in a subset (N = 41) of MC with longitudinal NfL and MRI data. In MC, elevated cross-sectional NfL was positively associated with WM hyperintensity lesion volume, mean diffusivity, radial diffusivity, and axial diffusivity and negatively with fractional anisotropy. Greater change in NfL levels in MC was associated with larger changes in fractional anisotropy, mean diffusivity, and radial diffusivity, all indicative of reduced WM integrity. There were no relationships with NfL in NC. Our results demonstrate that blood-based NfL levels reflect WM integrity and supports the view that blood levels of NfL are predictive of WM damage in the brain. This is a critical result in improving the interpretability of NfL as a marker of brain integrity, and for validating this emerging biomarker for future use in clinical and research settings across multiple neurodegenerative diseases. Serum NfL levels reflect white matter integrity in autosomal dominant Alzheimer disease. Associations between NfL and white matter imaging are present throughout all brain regions. Longitudinal white matter alterations are associated with changes in blood NfL. Results improve interpretability of NfL as a marker of brain integrity.
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17
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Anti-neurofilament antibodies and neurodegeneration: Markers and generators. J Neuroimmunol 2020; 344:577248. [PMID: 32344161 DOI: 10.1016/j.jneuroim.2020.577248] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 04/19/2020] [Accepted: 04/21/2020] [Indexed: 11/24/2022]
Abstract
Neuroaxonal injury and loss result in the release of cytoskeleton components, including neurofilaments, into the cerebrospinal fluid and peripheral blood. Once released, neurofilaments are highly immunogenic, inducing a specific antibody response. Anti-neurofilament antibody levels correlate with the progression of diverse neurological diseases; however, their role both in the pathogenesis of disease and as a tool for monitoring disease progression is not well understood. This study reviews the current literature on anti-neurofilament antibodies. We suggest the testing of anti-neurofilament antibodies be further developed for diagnosis and targeted for treatment.
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18
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Much More Than a Scaffold: Cytoskeletal Proteins in Neurological Disorders. Cells 2020; 9:cells9020358. [PMID: 32033020 PMCID: PMC7072452 DOI: 10.3390/cells9020358] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 02/08/2023] Open
Abstract
Recent observations related to the structure of the cytoskeleton in neurons and novel cytoskeletal abnormalities involved in the pathophysiology of some neurological diseases are changing our view on the function of the cytoskeletal proteins in the nervous system. These efforts allow a better understanding of the molecular mechanisms underlying neurological diseases and allow us to see beyond our current knowledge for the development of new treatments. The neuronal cytoskeleton can be described as an organelle formed by the three-dimensional lattice of the three main families of filaments: actin filaments, microtubules, and neurofilaments. This organelle organizes well-defined structures within neurons (cell bodies and axons), which allow their proper development and function through life. Here, we will provide an overview of both the basic and novel concepts related to those cytoskeletal proteins, which are emerging as potential targets in the study of the pathophysiological mechanisms underlying neurological disorders.
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19
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Alifirova VM, Kamenskikh EM, Koroleva ES. [Evaluation of serum neurofilament light chains levels for diagnosis, treatment monitoring and prognosis in multiple sclerosis]. Zh Nevrol Psikhiatr Im S S Korsakova 2020; 119:7-13. [PMID: 31934983 DOI: 10.17116/jnevro2019119107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pathophysiological processes in multiple sclerosis frequently not diagnosed by clinicians become available for analysis only on the basis of paraclinical data (biomarkers). Nowadays neurofilament light chain can be defined as a promising biomarker for multiple sclerosis (MS). Neurofilaments are a structural part of normal neuronal processes consisting of light, intermediate and heavy chains. However, a damage of neurons such as neurodegeneration or axonal damage causes the escape of neurofilaments into extracellular space. Cutting-edge highly sensitive methods make it possible to detect neurofilament light chains not only in the cerebrospinal fluid but also in the blood serum thus opening the opportunities to utilize them in routine diagnosis in clinical practice. This review comprises existing data on the possible opportunities for research of serum neurofilament light chains in terms of exacerbations, effectiveness of basic therapy, assessment of individual disability, the atrophy of central nervous system structures. Also, there is some information on comparison of two methods: routine MRI of the brain with the contrast agents and detection of serum neurofilament light chains.
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Affiliation(s)
| | | | - E S Koroleva
- Siberian State Medical University, Tomsk, Russia
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20
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Barretto TA, Park K, Maghen L, Park E, Kenigsberg S, Gallagher D, Liu E, Gauthier-Fisher A, Librach C, Baker A. Axon Degeneration Is Rescued with Human Umbilical Cord Perivascular Cells: A Potential Candidate for Neuroprotection After Traumatic Brain Injury. Stem Cells Dev 2019; 29:198-211. [PMID: 31701812 DOI: 10.1089/scd.2019.0135] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) leads to delayed secondary injury events consisting of cellular and molecular cascades that exacerbate the initial injury. Human umbilical cord perivascular cells (HUCPVCs) secrete neurotrophic and prosurvival factors. In this study, we examined the effects of HUCPVC in sympathetic axon and cortical axon survival models and sought to determine whether HUCPVC provide axonal survival cues. We then examined the effects of the HUCPVC in an in vivo fluid percussion injury model of TBI. Our data indicate that HUCPVCs express neurotrophic and neural survival factors. They also express and secrete relevant growth and survival proteins when cultured alone, or in the presence of injured axons. Coculture experiments indicate that HUCPVCs interact preferentially with axons when cocultured with sympathetic neurons and reduce axonal degeneration. Nerve growth factor withdrawal in axonal compartments resulted in 66 ± 3% axon degeneration, whereas HUCPVC coculture rescued axon degeneration to 35 ± 3%. Inhibition of Akt (LY294002) resulted in a significant increase in degeneration compared with HUCPVC cocultures (48 ± 7% degeneration). Under normoxic conditions, control cultures showed 39 ± 5% degeneration. Oxygen glucose deprivation (OGD) resulted in 58 ± 3% degeneration and OGD HUCPVC cocultures reduced degeneration to 34 ± 5% (p < 0.05). In an in vivo model of TBI, immunohistochemical analysis of NF200 showed improved axon morphology in HUCPVC-treated animals compared with injured animals. These data presented in this study indicate an important role for perivascular cells in protecting axons from injury and a potential cell-based therapy to treat secondary injury after TBI.
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Affiliation(s)
- Tanya A Barretto
- Keenan Research Center, St. Michael's Hospital, Toronto, Canada.,Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Katya Park
- CReATe Fertility Center, Toronto, Canada
| | | | - Eugene Park
- Institute of Medical Science, University of Toronto, Toronto, Canada
| | | | | | - Elaine Liu
- Institute of Medical Science, University of Toronto, Toronto, Canada
| | | | - Clifford Librach
- CReATe Fertility Center, Toronto, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada.,Division of Reproductive Endocrinology and Infertility, Departments of Obstetrics and Gynecology, Sunnybrook Health Sciences Center and Women's College Hospital, Toronto, Canada
| | - Andrew Baker
- Keenan Research Center, St. Michael's Hospital, Toronto, Canada.,Institute of Medical Science, University of Toronto, Toronto, Canada.,Department of Critical Care, St. Michael's Hospital, Toronto, Canada.,Department of Anesthesia, University of Toronto, Toronto, Canada
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21
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Hahn I, Voelzmann A, Liew YT, Costa-Gomes B, Prokop A. The model of local axon homeostasis - explaining the role and regulation of microtubule bundles in axon maintenance and pathology. Neural Dev 2019; 14:11. [PMID: 31706327 PMCID: PMC6842214 DOI: 10.1186/s13064-019-0134-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 10/02/2019] [Indexed: 12/20/2022] Open
Abstract
Axons are the slender, cable-like, up to meter-long projections of neurons that electrically wire our brains and bodies. In spite of their challenging morphology, they usually need to be maintained for an organism's lifetime. This makes them key lesion sites in pathological processes of ageing, injury and neurodegeneration. The morphology and physiology of axons crucially depends on the parallel bundles of microtubules (MTs), running all along to serve as their structural backbones and highways for life-sustaining cargo transport and organelle dynamics. Understanding how these bundles are formed and then maintained will provide important explanations for axon biology and pathology. Currently, much is known about MTs and the proteins that bind and regulate them, but very little about how these factors functionally integrate to regulate axon biology. As an attempt to bridge between molecular mechanisms and their cellular relevance, we explain here the model of local axon homeostasis, based on our own experiments in Drosophila and published data primarily from vertebrates/mammals as well as C. elegans. The model proposes that (1) the physical forces imposed by motor protein-driven transport and dynamics in the confined axonal space, are a life-sustaining necessity, but pose a strong bias for MT bundles to become disorganised. (2) To counterbalance this risk, MT-binding and -regulating proteins of different classes work together to maintain and protect MT bundles as necessary transport highways. Loss of balance between these two fundamental processes can explain the development of axonopathies, in particular those linking to MT-regulating proteins, motors and transport defects. With this perspective in mind, we hope that more researchers incorporate MTs into their work, thus enhancing our chances of deciphering the complex regulatory networks that underpin axon biology and pathology.
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Affiliation(s)
- Ines Hahn
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - André Voelzmann
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - Yu-Ting Liew
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - Beatriz Costa-Gomes
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK
| | - Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, The University of Manchester, School of Biology, Manchester, UK.
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22
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Klymkowsky MW. Filaments and phenotypes: cellular roles and orphan effects associated with mutations in cytoplasmic intermediate filament proteins. F1000Res 2019; 8. [PMID: 31602295 PMCID: PMC6774051 DOI: 10.12688/f1000research.19950.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/20/2019] [Indexed: 12/11/2022] Open
Abstract
Cytoplasmic intermediate filaments (IFs) surround the nucleus and are often anchored at membrane sites to form effectively transcellular networks. Mutations in IF proteins (IFps) have revealed mechanical roles in epidermis, muscle, liver, and neurons. At the same time, there have been phenotypic surprises, illustrated by the ability to generate viable and fertile mice null for a number of IFp-encoding genes, including vimentin. Yet in humans, the vimentin ( VIM) gene displays a high probability of intolerance to loss-of-function mutations, indicating an essential role. A number of subtle and not so subtle IF-associated phenotypes have been identified, often linked to mechanical or metabolic stresses, some of which have been found to be ameliorated by the over-expression of molecular chaperones, suggesting that such phenotypes arise from what might be termed "orphan" effects as opposed to the absence of the IF network per se, an idea originally suggested by Toivola et al. and Pekny and Lane.
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Affiliation(s)
- Michael W Klymkowsky
- Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, Boulder, CO, 80303, USA
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23
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Didonna A, Opal P. The role of neurofilament aggregation in neurodegeneration: lessons from rare inherited neurological disorders. Mol Neurodegener 2019; 14:19. [PMID: 31097008 PMCID: PMC6524292 DOI: 10.1186/s13024-019-0318-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 04/26/2019] [Indexed: 12/13/2022] Open
Abstract
Many neurodegenerative disorders, including Parkinson's, Alzheimer's, and amyotrophic lateral sclerosis, are well known to involve the accumulation of disease-specific proteins. Less well known are the accumulations of another set of proteins, neuronal intermediate filaments (NFs), which have been observed in these diseases for decades. NFs belong to the family of cytoskeletal intermediate filament proteins (IFs) that give cells their shape; they determine axonal caliber, which controls signal conduction; and they regulate the transport of synaptic vesicles and modulate synaptic plasticity by binding to neurotransmitter receptors. In the last two decades, a number of rare disorders caused by mutations in genes that encode NFs or regulate their metabolism have been discovered. These less prevalent disorders are providing novel insights into the role of NF aggregation in the more common neurological disorders.
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Affiliation(s)
- Alessandro Didonna
- Department of Neurology and Weill Institute for Neurosciences, University of California at San Francisco, San Francisco, CA, 94158, USA
| | - Puneet Opal
- Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA. .,Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA.
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24
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Khalil M, Teunissen CE, Otto M, Piehl F, Sormani MP, Gattringer T, Barro C, Kappos L, Comabella M, Fazekas F, Petzold A, Blennow K, Zetterberg H, Kuhle J. Neurofilaments as biomarkers in neurological disorders. Nat Rev Neurol 2018; 14:577-589. [DOI: 10.1038/s41582-018-0058-z] [Citation(s) in RCA: 767] [Impact Index Per Article: 127.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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25
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Villalón E, Barry DM, Byers N, Frizzi K, Jones MR, Landayan DS, Dale JM, Downer NL, Calcutt NA, Garcia ML. Internode length is reduced during myelination and remyelination by neurofilament medium phosphorylation in motor axons. Exp Neurol 2018; 306:158-168. [PMID: 29772247 PMCID: PMC5994378 DOI: 10.1016/j.expneurol.2018.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 05/03/2018] [Accepted: 05/09/2018] [Indexed: 01/04/2023]
Abstract
The distance between nodes of Ranvier, referred to as internode length, positively correlates with axon diameter, and is optimized during development to ensure maximal neuronal conduction velocity. Following myelin loss, internode length is reestablished through remyelination. However, remyelination results in short internode lengths and reduced conduction rates. We analyzed the potential role of neurofilament phosphorylation in regulating internode length during remyelination and myelination. Following ethidium bromide induced demyelination, levels of neurofilament medium (NF-M) and heavy (NF-H) phosphorylation were unaffected. Preventing NF-M lysine-serine-proline (KSP) repeat phosphorylation increased internode length by 30% after remyelination. To further analyze the role of NF-M phosphorylation in regulating internode length, gene replacement was used to produce mice in which all KSP serine residues were replaced with glutamate to mimic constitutive phosphorylation. Mimicking constitutive KSP phosphorylation reduced internode length by 16% during myelination and motor nerve conduction velocity by ~27% without altering sensory nerve structure or function. Our results suggest that NF-M KSP phosphorylation is part of a cooperative mechanism between axons and Schwann cells that together determine internode length, and suggest motor and sensory axons utilize different mechanisms to establish internode length.
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Affiliation(s)
- Eric Villalón
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States
| | - Devin M Barry
- Department of Anesthesiology, Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - Nathan Byers
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, United States
| | - Katie Frizzi
- Department of Pathology, University of California San Diego, La Jolla, CA 92093, United States
| | - Maria R Jones
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States
| | - Dan S Landayan
- Department of Quantitative and Systems Biology, University of California Merced, Merced, CA 95343, United States
| | - Jeffrey M Dale
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States
| | - Natalie L Downer
- Department of Biological Science, Moberly Area Community College, Moberly, MO 65270, United States
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA 92093, United States
| | - Michael L Garcia
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States.
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Horga A, Laurà M, Jaunmuktane Z, Jerath NU, Gonzalez MA, Polke JM, Poh R, Blake JC, Liu YT, Wiethoff S, Bettencourt C, Lunn MP, Manji H, Hanna MG, Houlden H, Brandner S, Züchner S, Shy M, Reilly MM. Genetic and clinical characteristics of NEFL-related Charcot-Marie-Tooth disease. J Neurol Neurosurg Psychiatry 2017; 88:575-585. [PMID: 28501821 PMCID: PMC5580821 DOI: 10.1136/jnnp-2016-315077] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/20/2017] [Accepted: 01/24/2017] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To analyse and describe the clinical and genetic spectrum of Charcot-Marie-Tooth disease (CMT) caused by mutations in the neurofilament light polypeptide gene (NEFL). METHODS Combined analysis of newly identified patients with NEFL-related CMT and all previously reported cases from the literature. RESULTS Five new unrelated patients with CMT carrying the NEFL mutations P8R and N98S and the novel variant L311P were identified. Combined data from these cases and 62 kindreds from the literature revealed four common mutations (P8R, P22S, N98S and E396K) and three mutational hotspots accounting for 37 (55%) and 50 (75%) kindreds, respectively. Eight patients had de novo mutations. Loss of large-myelinated fibres was a uniform feature in a total of 21 sural nerve biopsies and 'onion bulb' formations and/or thin myelin sheaths were observed in 14 (67%) of them. The neurophysiological phenotype was broad but most patients with E90K and N98S had upper limb motor conduction velocities <38 m/s. Age of onset was ≤3 years in 25 cases. Pyramidal tract signs were described in 13 patients and 7 patients were initially diagnosed with or tested for inherited ataxia. Patients with E90K and N98S frequently presented before age 3 years and developed hearing loss or other neurological features including ataxia and/or cerebellar atrophy on brain MRI. CONCLUSIONS NEFL-related CMT is clinically and genetically heterogeneous. Based on this study, however, we propose mutational hotspots and relevant clinical-genetic associations that may be helpful in the evaluation of NEFL sequence variants and the differential diagnosis with other forms of CMT.
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Affiliation(s)
- Alejandro Horga
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK.,Department of Neurology, Hospital Clinico Universitario San Carlos, Madrid, Spain
| | - Matilde Laurà
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK.,UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, UK
| | - Zane Jaunmuktane
- Division of Neuropathology and Department of Neurodegenerative Disease, The National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, London, UK
| | | | - Michael A Gonzalez
- Department of Human Genetics and Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, Florida, USA.,The Genesis Project Foundation, The Genesis Project Foundation, Miami, Florida, USA
| | - James M Polke
- Department of Neurogenetics, The National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, London, UK.,Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Roy Poh
- Department of Neurogenetics, The National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, London, UK
| | - Julian C Blake
- Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery (and Norfolk and Norwich University Hospital), London, UK
| | - Yo-Tsen Liu
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK.,Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Sarah Wiethoff
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | | | - Michael Pt Lunn
- Department of Neurology, National Hospital for Neurology and Neurosurgery, London, UK
| | - Hadi Manji
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Henry Houlden
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Sebastian Brandner
- Division of Neuropatholgoy, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | | | - Michael Shy
- Department of Neurology, University of Iowa, Iowa City, Iowa, USA.,Wayne State University, Michigan, Michigan, USA
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK.,MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
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Kirkcaldie MTK, Dwyer ST. The third wave: Intermediate filaments in the maturing nervous system. Mol Cell Neurosci 2017; 84:68-76. [PMID: 28554564 DOI: 10.1016/j.mcn.2017.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/10/2017] [Accepted: 05/25/2017] [Indexed: 01/16/2023] Open
Abstract
Intermediate filaments are critical for the extreme structural specialisations of neurons, providing integrity in dynamic environments and efficient communication along axons a metre or more in length. As neurons mature, an initial expression of nestin and vimentin gives way to the neurofilament triplet proteins and α-internexin, substituted by peripherin in axons outside the CNS, which physically consolidate axons as they elongate and find their targets. Once connection is established, these proteins are transported, assembled, stabilised and modified, structurally transforming axons and dendrites as they acquire their full function. The interaction between these neurons and myelinating glial cells optimises the structure of axons for peak functional efficiency, a property retained across their lifespan. This finely calibrated structural regulation allows the nervous system to maintain timing precision and efficient control across large distances throughout somatic growth and, in maturity, as a plasticity mechanism allowing functional adaptation.
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Affiliation(s)
- Matthew T K Kirkcaldie
- School of Medicine, Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia.
| | - Samuel T Dwyer
- School of Medicine, Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia
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Yuan A, Rao MV, Veeranna, Nixon RA. Neurofilaments and Neurofilament Proteins in Health and Disease. Cold Spring Harb Perspect Biol 2017; 9:9/4/a018309. [PMID: 28373358 DOI: 10.1101/cshperspect.a018309] [Citation(s) in RCA: 436] [Impact Index Per Article: 62.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
SUMMARYNeurofilaments (NFs) are unique among tissue-specific classes of intermediate filaments (IFs) in being heteropolymers composed of four subunits (NF-L [neurofilament light]; NF-M [neurofilament middle]; NF-H [neurofilament heavy]; and α-internexin or peripherin), each having different domain structures and functions. Here, we review how NFs provide structural support for the highly asymmetric geometries of neurons and, especially, for the marked radial expansion of myelinated axons crucial for effective nerve conduction velocity. NFs in axons extensively cross-bridge and interconnect with other non-IF components of the cytoskeleton, including microtubules, actin filaments, and other fibrous cytoskeletal elements, to establish a regionally specialized network that undergoes exceptionally slow local turnover and serves as a docking platform to organize other organelles and proteins. We also discuss how a small pool of oligomeric and short filamentous precursors in the slow phase of axonal transport maintains this network. A complex pattern of phosphorylation and dephosphorylation events on each subunit modulates filament assembly, turnover, and organization within the axonal cytoskeleton. Multiple factors, and especially turnover rate, determine the size of the network, which can vary substantially along the axon. NF gene mutations cause several neuroaxonal disorders characterized by disrupted subunit assembly and NF aggregation. Additional NF alterations are associated with varied neuropsychiatric disorders. New evidence that subunits of NFs exist within postsynaptic terminal boutons and influence neurotransmission suggests how NF proteins might contribute to normal synaptic function and neuropsychiatric disease states.
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Affiliation(s)
- Aidong Yuan
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016
| | - Mala V Rao
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016
| | - Veeranna
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016
| | - Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016.,Cell Biology, New York University School of Medicine, New York, New York 10016
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Vickers J, Kirkcaldie M, Phipps A, King A. Alterations in neurofilaments and the transformation of the cytoskeleton in axons may provide insight into the aberrant neuronal changes of Alzheimer’s disease. Brain Res Bull 2016; 126:324-333. [DOI: 10.1016/j.brainresbull.2016.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 01/09/2023]
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Yuan A, Nixon RA. Specialized roles of neurofilament proteins in synapses: Relevance to neuropsychiatric disorders. Brain Res Bull 2016; 126:334-346. [PMID: 27609296 PMCID: PMC5079776 DOI: 10.1016/j.brainresbull.2016.09.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/02/2016] [Accepted: 09/03/2016] [Indexed: 01/05/2023]
Abstract
Neurofilaments are uniquely complex among classes of intermediate filaments in being composed of four subunits (NFL, NFM, NFH and alpha-internexin in the CNS) that differ in structure, regulation, and function. Although neurofilaments have been traditionally viewed as axonal structural components, recent evidence has revealed that distinctive assemblies of neurofilament subunits are integral components of synapses, especially at postsynaptic sites. Within the synaptic compartment, the individual subunits differentially modulate neurotransmission and behavior through interactions with specific neurotransmitter receptors. These newly uncovered functions suggest that alterations of neurofilament proteins not only underlie axonopathy in various neurological disorders but also may play vital roles in cognition and neuropsychiatric diseases. Here, we review evidence that synaptic neurofilament proteins are a sizable population in the CNS and we advance the concept that changes in the levels or post-translational modification of individual NF subunits contribute to synaptic and behavioral dysfunction in certain neuropsychiatric conditions.
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Affiliation(s)
- Aidong Yuan
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, 10962, United States; Departments of Psychiatry, New York University School of Medicine, New York, NY, 10016, United States.
| | - Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, 10962, United States; Departments of Psychiatry, New York University School of Medicine, New York, NY, 10016, United States; Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, United States.
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Kirkcaldie MTK, Collins JM. The axon as a physical structure in health and acute trauma. J Chem Neuroanat 2016; 76:9-18. [PMID: 27233660 DOI: 10.1016/j.jchemneu.2016.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 05/22/2016] [Accepted: 05/22/2016] [Indexed: 10/21/2022]
Abstract
The physical structure of neurons - dendrites converging on the soma, with an axon conveying activity to distant locations - is uniquely tied to their function. To perform their role, axons need to maintain structural precision in the soft, gelatinous environment of the central nervous system and the dynamic, flexible paths of nerves in the periphery. This requires close mechanical coupling between axons and the surrounding tissue, as well as an elastic, robust axoplasm resistant to pinching and flattening, and capable of sustaining transport despite physical distortion. These mechanical properties arise primarily from the properties of the internal cytoskeleton, coupled to the axonal membrane and the extracellular matrix. In particular, the two large constituents of the internal cytoskeleton, microtubules and neurofilaments, are braced against each other and flexibly interlinked by specialised proteins. Recent evidence suggests that the primary function of neurofilament sidearms is to structure the axoplasm into a linearly organised, elastic gel. This provides support and structure to the contents of axons in peripheral nerves subject to bending, protecting the relatively brittle microtubule bundles and maintaining them as transport conduits. Furthermore, a substantial proportion of axons are myelinated, and this thick jacket of membrane wrappings alters the form, function and internal composition of the axons to which it is applied. Together these structures determine the physical properties and integrity of neural tissue, both under conditions of normal movement, and in response to physical trauma. The effects of traumatic injury are directly dependent on the physical properties of neural tissue, especially axons, and because of axons' extreme structural specialisation, post-traumatic effects are usually characterised by particular modes of axonal damage. The physical realities of axons in neural tissue are integral to both normal function and their response to injury, and require specific consideration in evaluating research models of neurotrauma.
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Affiliation(s)
- Matthew T K Kirkcaldie
- School of Medicine, University of Tasmania, Australia; Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia.
| | - Jessica M Collins
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia
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Methyl-Arginine Profile of Brain from Aged PINK1-KO+A53T-SNCA Mice Suggests Altered Mitochondrial Biogenesis. PARKINSONS DISEASE 2016; 2016:4686185. [PMID: 27034888 PMCID: PMC4791501 DOI: 10.1155/2016/4686185] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 01/13/2016] [Accepted: 01/14/2016] [Indexed: 11/29/2022]
Abstract
Hereditary Parkinson's disease can be triggered by an autosomal dominant overdose of alpha-Synuclein (SNCA) or the autosomal recessive deficiency of PINK1. We recently showed that the combination of PINK1-knockout with overexpression of A53T-SNCA in double mutant (DM) mice potentiates phenotypes and reduces survival. Now we studied brain hemispheres of DM mice at age of 18 months in a hypothesis-free approach, employing a quantitative label-free global proteomic mass spectrometry scan of posttranslational modifications focusing on methyl-arginine. The strongest effects were documented for the adhesion modulator CMAS, the mRNA decapping/deadenylation factor PATL1, and the synaptic plasticity mediator CRTC1/TORC1. In addition, an intriguing effect was observed for the splicing factor PSF/SFPQ, known to interact with the dopaminergic differentiation factor NURR1 as well as with DJ-1, the protein responsible for the autosomal recessive PARK7 variant of PD. CRTC1, PSF, and DJ-1 are modulators of PGC1alpha and of mitochondrial biogenesis. This pathway was further stressed by dysregulations of oxygen sensor EGLN3 and of nuclear TMPO. PSF and TMPO cooperate with dopaminergic differentiation factors LMX1B and NURR1. Further dysregulations concerned PRR18, TRIO, HNRNPA1, DMWD, WAVE1, ILDR2, DBNDD1, and NFM. Thus, we report selective novel endogenous stress responses in brain, which highlight early dysregulations of mitochondrial homeostasis and midbrain vulnerability.
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Jones MR, Villalón E, Garcia ML. Genetic Manipulation of Neurofilament Protein Phosphorylation. Methods Enzymol 2015; 568:461-76. [PMID: 26795480 DOI: 10.1016/bs.mie.2015.07.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Neurofilament biology is important to understanding structural properties of axons, such as establishment of axonal diameter by radial growth. In order to study the function of neurofilaments, a series of genetically modified mice have been generated. Here, we describe a brief history of genetic modifications used to study neurofilaments, as well as an overview of the steps required to generate a gene-targeted mouse. In addition, we describe steps utilized to analyze neurofilament phosphorylation status using immunoblotting. Taken together, these provide comprehensive analysis of neurofilament function in vivo, which can be applied to many systems.
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Affiliation(s)
- Maria R Jones
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA; C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
| | - Eric Villalón
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA; C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
| | - Michael L Garcia
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA; C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA.
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Yuan A, Hassinger L, Rao MV, Julien JP, Miller CCJ, Nixon RA. Dissociation of Axonal Neurofilament Content from Its Transport Rate. PLoS One 2015. [PMID: 26208164 PMCID: PMC4514674 DOI: 10.1371/journal.pone.0133848] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The axonal cytoskeleton of neurofilament (NF) is a long-lived network of fibrous elements believed to be a stationary structure maintained by a small pool of transported cytoskeletal precursors. Accordingly, it may be predicted that NF content in axons can vary independently from the transport rate of NF. In the present report, we confirm this prediction by showing that human NFH transgenic mice and transgenic mice expressing human NFL Ser55 (Asp) develop nearly identical abnormal patterns of NF accumulation and distribution in association with opposite changes in NF slow transport rates. We also show that the rate of NF transport in wild-type mice remains constant along a length of the optic axon where NF content varies 3-fold. Moreover, knockout mice lacking NFH develop even more extreme (6-fold) proximal to distal variation in NF number, which is associated with a normal wild-type rate of NF transport. The independence of regional NF content and NF transport is consistent with previous evidence suggesting that the rate of incorporation of transported NF precursors into a metabolically stable stationary cytoskeletal network is the major determinant of axonal NF content, enabling the generation of the striking local variations in NF number seen along axons.
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Affiliation(s)
- Aidong Yuan
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, United States of America
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (AY); (RAN)
| | - Linda Hassinger
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, United States of America
| | - Mala V. Rao
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, United States of America
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
| | - Jean-Pierre Julien
- Centre de Recherche du Centre Hospitalier de l'Université Laval, Département d'anatomie et physiologie de l'Université Laval, Québec, Canada
| | - Christopher C. J. Miller
- Department of Neuroscience, Institute of Psychiatry, Kings College London, London, United Kingdom
- Clinical Neurosciences, Institute of Psychiatry, Kings College London, London, United Kingdom
| | - Ralph A. Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, United States of America
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (AY); (RAN)
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Chang RYK, Etheridge N, Nouwens AS, Dodd PR. SWATH analysis of the synaptic proteome in Alzheimer's disease. Neurochem Int 2015; 87:1-12. [PMID: 25958317 DOI: 10.1016/j.neuint.2015.04.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 10/23/2022]
Abstract
Brain tissue from Alzheimer's disease patients exhibits synaptic degeneration in selected regions. Synaptic dysfunction occurs early in the disease and is a primary pathological target for treatment. The molecular mechanisms underlying this degeneration remain unknown. Quantifying the synaptic proteome in autopsy brain and comparing tissue from Alzheimer's disease cases and subjects with normal aging are critical to understanding the molecular mechanisms associated with Alzheimer pathology. We isolated synaptosomes from hippocampus and motor cortex so as to reduce sample complexity relative to whole-tissue homogenates. Synaptosomal extracts were subjected to strong cation exchange (SCX) fractionation to further partition sample complexity; each fraction received SWATH-based information-dependent acquisition to generate a comprehensive peptide-ion library. The expression of synaptic proteins from AD hippocampus and motor cortex was then compared between groups. A total of 2077 unique proteins were identified at a critical local false discovery rate <5%. Thirty of these, including 17 novel proteins, exhibited significant expression differences between cases and controls; these proteins are involved in cellular functions including structural maintenance, signal transduction, autophagy, oxidative stress, and proteasome activity, or they have synaptic-vesicle related or energy-related functions. Differentially expressed proteins were subjected to pathway analysis to identify protein-protein interactions. This revealed that the most perturbed molecular and cellular functions were cellular assembly and organization. Core analysis revealed RhoA signaling to be the top canonical pathway. Network analysis showed that differentially expressed proteins were related to cellular assembly and organization, and cellular function and maintenance. This is the first study to combine SCX fractionation with SWATH analysis. SWATH is a promising new technique that can greatly enhance protein identification in any proteome, and has many other benefits; however, there are limitations yet to be resolved.
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Affiliation(s)
| | - Naomi Etheridge
- School of Chemistry and Molecular Biosciences, University of Queensland, Australia
| | - Amanda S Nouwens
- School of Chemistry and Molecular Biosciences, University of Queensland, Australia
| | - Peter R Dodd
- School of Chemistry and Molecular Biosciences, University of Queensland, Australia.
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37
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Gentil BJ, Tibshirani M, Durham HD. Neurofilament dynamics and involvement in neurological disorders. Cell Tissue Res 2015; 360:609-20. [PMID: 25567110 DOI: 10.1007/s00441-014-2082-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 11/19/2014] [Indexed: 12/21/2022]
Abstract
Neurons are extremely polarised cells in which the cytoskeleton, composed of microtubules, microfilaments and neurofilaments, plays a crucial role in maintaining structure and function. Neurofilaments, the 10-nm intermediate filaments of neurons, provide structure and mechanoresistance but also provide a scaffolding for the organization of the nucleus and organelles such as mitochondria and ER. Disruption of neurofilament organization and expression or metabolism of neurofilament proteins is characteristic of certain neurological syndromes including Amyotrophic Lateral Sclerosis, Charcot-Marie-Tooth sensorimotor neuropathies and Giant Axonal Neuropathy. Microfluorometric live imaging techniques have been instrumental in revealing the dynamics of neurofilament assembly and transport and their functions in organizing intracellular organelle networks. The insolubility of neurofilament proteins has limited identifying interactors by conventional biochemical techniques but yeast two-hybrid experiments have revealed new roles for oligomeric, nonfilamentous structures including vesicular trafficking. Although having long half-lives, new evidence points to degradation of subunits by the ubiquitin-proteasome system as a mechanism of normal turnover. Although certain E3-ligases ubiquitinating neurofilament proteins have been identified, the overall process of neurofilament degradation is not well understood. We review these mechanisms of neurofilament homeostasis and abnormalities in motor neuron and peripheral nerve disorders. Much remains to discover about the disruption of processes that leads to their pathological aggregation and accumulation and the relevance to pathogenesis. Understanding these mechanisms is crucial for identifying novel therapeutic strategies.
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Affiliation(s)
- Benoit J Gentil
- Department of Neurology/Neurosurgery and Montreal Neurological Institute, McGill University, Montreal, QC, H3A 2B4, Canada,
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Specific calpain inhibition by calpastatin prevents tauopathy and neurodegeneration and restores normal lifespan in tau P301L mice. J Neurosci 2014; 34:9222-34. [PMID: 25009256 DOI: 10.1523/jneurosci.1132-14.2014] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Tau pathogenicity in Alzheimer's disease and other tauopathies is thought to involve the generation of hyperphosphorylated, truncated, and oligomeric tau species with enhanced neurotoxicity, although the generative mechanisms and the implications for disease therapy are not well understood. Here, we report a striking rescue from mutant tau toxicity in the JNPL3 mouse model of tauopathy. We show that pathological activation of calpains gives rise to a range of potentially toxic forms of tau, directly, and by activating cdk5. Calpain overactivation in brains of these mice is accelerated as a result of the marked depletion of the endogenous calpain inhibitor, calpastatin. When levels of this inhibitor are restored in neurons of JNPL3 mice by overexpressing calpastatin, tauopathy is prevented, including calpain-mediated breakdown of cytoskeletal proteins, cdk5 activation, tau hyperphosphorylation, formation of potentially neurotoxic tau fragments by either calpain or caspase-3, and tau oligomerization. Calpastatin overexpression also prevents loss of motor axons, delays disease onset, and extends survival of JNPL3 mice by 3 months to within the range of normal lifespan. Our findings support the therapeutic promise of highly specific calpain inhibition in the treatment of tauopathies and other neurodegenerative states.
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39
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Yang C, Sun L, Li X, Xie L, Yu M, Feng L, Jiang Z, Guo W, Tian W. The potential of dental stem cells differentiating into neurogenic cell lineage after cultivation in different modes in vitro. Cell Reprogram 2014; 16:379-91. [PMID: 25072651 DOI: 10.1089/cell.2014.0026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Trauma or degenerative diseases of the central nervous system (CNS) cause the loss of neurons or glial cells. Stem cell transplantation has become a vital strategy for CNS regeneration. It is necessary to effectively induce nonneurogenic stem cells to differentiate into neurogenic cell lineages because of the limited source of neurogenic stem cells, relatively difficult cultivation, and ethical issues. Previous studies have found that dental stem cells can be used for transplantation therapy. The aim of this study was to explore a better inductive mode and time point for dental stem cells to differentiate into neural-like cells and evaluate a better candidate cell. In this study, dental follicle stem cells (DFSCs), dental papilla stem cells (DPSCs), and stem cells from apical papilla (SCAPs) were cultivated in five different modes. The proliferation ability, morphology, and expression of neural marker genes were analyzed. Results showed that DFSCs showed a higher proliferation potential. The proliferation was decreased after cultivation in chemical inductive medium as cultivation modes 3 and 5. The cells could present neural-like cell morphology after cultivation with human epidermal growth factor (EGF) and fibroblast growth factor-basic (bFGF) as cultivation modes 4 and 5. The vast majority of DFSCs gene expression levels in mode 4 on the third day was upregulated significantly. In conclusion, our data suggested that different dental stem cells exhibited different neural differentiation potentials. DFSCs might be the better candidate cell type. Furthermore, cultivation mode 4 and timing of the third day may promote differentiation into neurogenic cell lineages more effectively before transplantation to treat neurological diseases.
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Affiliation(s)
- Chao Yang
- 1 National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University , Chengdu, 610041, China
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Affiliation(s)
- Aidong Yuan
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, NY 10962, USA.
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Innocenti GM, Vercelli A, Caminiti R. The diameter of cortical axons depends both on the area of origin and target. ACTA ACUST UNITED AC 2013; 24:2178-88. [PMID: 23529006 DOI: 10.1093/cercor/bht070] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In primates, different cortical areas send axons of different diameters into comparable tracts, notably the corpus callosum (Tomasi S, Caminiti R, Innocenti GM. 2012. Areal differences in diameter and length of corticofugal projections. Cereb Cortex. 22:1463-1472). We now explored if an area also sends axons of different diameters to different targets. We find that the parietal area PEc sends thicker axons to area 4 and 6, and thinner ones to the cingulate region (area 24). Areas 4 and 9, each sends axons of different diameters to the nucleus caudatus, to different levels of the internal capsule, and to the thalamus. The internal capsule receives the thickest axon, followed by thalamus and nucleus caudatus. The 2 areas (4 and 9) differ in the diameter and length of axons to corresponding targets. We calculated how diameter determines conduction velocity of the axons and together with pathway length determines transmission delays between different brain sites. We propose that projections from and within the cerebral cortex consist of a complex system of lines of communication with different geometrical and time computing properties.
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Affiliation(s)
| | - Alessandro Vercelli
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Department of Neuroscience, University of Turin, Turin, Italy and
| | - Roberto Caminiti
- Department of Physiology and Pharmacology, University of Rome Sapienza, Rome, Italy
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Holmgren A, Bouhy D, Timmerman V. Neurofilament phosphorylation and their proline-directed kinases in health and disease. J Peripher Nerv Syst 2012; 17:365-76. [DOI: 10.1111/j.1529-8027.2012.00434.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Rao MV, Yuan A, Campbell J, Kumar A, Nixon RA. The C-terminal domains of NF-H and NF-M subunits maintain axonal neurofilament content by blocking turnover of the stationary neurofilament network. PLoS One 2012; 7:e44320. [PMID: 23028520 PMCID: PMC3448626 DOI: 10.1371/journal.pone.0044320] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/01/2012] [Indexed: 02/03/2023] Open
Abstract
Newly synthesized neurofilaments or protofilaments are incorporated into a highly stable stationary cytoskeleton network as they are transported along axons. Although the heavily phosphorylated carboxyl-terminal tail domains of the heavy and medium neurofilament (NF) subunits have been proposed to contribute to this process and particularly to stability of this structure, their function is still obscure. Here we show in NF-H/M tail deletion [NF-(H/M)(tailΔ)] mice that the deletion of both of these domains selectively lowers NF levels 3-6 fold along optic axons without altering either rates of subunit synthesis or the rate of slow axonal transport of NF. Pulse labeling studies carried out over 90 days revealed a significantly faster rate of disappearance of NF from the stationary NF network of optic axons in NF-(H/M)(tailΔ) mice. Faster NF disappearance was accompanied by elevated levels of NF-L proteolytic fragments in NF-(H/M)(tailΔ) axons. We conclude that NF-H and NF-M C-terminal domains do not normally regulate NF transport rates as previously proposed, but instead increase the proteolytic resistance of NF, thereby stabilizing the stationary neurofilament cytoskeleton along axons.
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Affiliation(s)
- Mala V Rao
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, United States of America.
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Wakeling EN, Joussemet B, Costiou P, Fanuel D, Moullier P, Barkats M, Fyfe JC. Failure of lower motor neuron radial outgrowth precedes retrograde degeneration in a feline model of spinal muscular atrophy. J Comp Neurol 2012; 520:1737-50. [PMID: 22120001 DOI: 10.1002/cne.23010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Feline spinal muscular atrophy (SMA) is a fully penetrant, autosomal recessive lower motor neuron disease in domestic cats that clinically resembles human SMA Type III. A whole genome linkage scan identified a ∼140-kb deletion that abrogates expression of LIX1, a novel SMA candidate gene of unknown function. To characterize the progression of feline SMA, we assessed pathological changes in muscle and spinal cord from 3 days of age to beyond onset of clinical signs. Electromyographic (EMG) analysis indicating denervation occurred between 10 and 12 weeks, with the first neurological signs occurring at the same time. Compound motor action potential (CMAP) amplitudes were significantly reduced in the soleus and extensor carpi radialis muscles at 8-11 weeks. Quadriceps femoris muscle fibers from affected cats appeared smaller at 10 weeks; by 12 weeks atrophic fibers were more prevalent than in age-matched controls. In affected cats, significant loss of L5 ventral root axons was observed at 12 weeks. By 21 weeks of age, affected cats had 40% fewer L5 motor axons than normal. There was no significant difference in total L5 soma number, even at 21 weeks; thus degeneration begins distal to the cell body and proceeds retrogradely. Morphometric analysis of L5 ventral roots and horns revealed that 4 weeks prior to axon loss, motor axons in affected cats failed to undergo radial enlargement, suggesting a role for the putative disease gene LIX1 in radial growth of axons.
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Affiliation(s)
- Erin N Wakeling
- Genetics Program, Michigan State University East Lansing, Michigan 48824, USA.
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Neurofilament Phosphorylation during Development and Disease: Which Came First, the Phosphorylation or the Accumulation? JOURNAL OF AMINO ACIDS 2012; 2012:382107. [PMID: 22570767 PMCID: PMC3337605 DOI: 10.1155/2012/382107] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 01/31/2012] [Indexed: 11/17/2022]
Abstract
Posttranslational modification of proteins is a ubiquitous cellular mechanism for regulating protein function. Some of the most heavily modified neuronal proteins are cytoskeletal proteins of long myelinated axons referred to as neurofilaments (NFs). NFs are type IV intermediate filaments (IFs) that can be composed of four subunits, neurofilament heavy (NF-H), neurofilament medium (NF-M), neurofilament light (NF-L), and α-internexin. Within wild type axons, NFs are responsible for mediating radial growth, a process that determines axonal diameter. NFs are phosphorylated on highly conserved lysine-serine-proline (KSP) repeats located along the C-termini of both NF-M and NF-H within myelinated axonal regions. Phosphorylation is thought to regulate aspects of NF transport and function. However, a key pathological hallmark of several neurodegenerative diseases is ectopic accumulation and phosphorylation of NFs. The goal of this review is to provide an overview of the posttranslational modifications that occur in both normal and diseased axons. We review evidence that challenges the role of KSP phosphorylation as essential for radial growth and suggests an alternative role for NF phosphorylation in myelinated axons. Furthermore, we demonstrate that regulation of NF phosphorylation dynamics may be essential to avoiding NF accumulations.
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Cantuti-Castelvetri L, Zhu H, Givogri MI, Chidavaenzi RL, Lopez-Rosas A, Bongarzone ER. Psychosine induces the dephosphorylation of neurofilaments by deregulation of PP1 and PP2A phosphatases. Neurobiol Dis 2012; 46:325-35. [PMID: 22326830 DOI: 10.1016/j.nbd.2012.01.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 01/16/2012] [Accepted: 01/26/2012] [Indexed: 11/25/2022] Open
Abstract
Patients with Krabbe disease, a genetic demyelinating syndrome caused by deficiency of galactosyl-ceramidase and the resulting accumulation of galactosyl-sphingolipids, develop signs of a dying-back axonopathy compounded by a deficiency of large-caliber axons. Here, we show that axonal caliber in Twitcher mice, an animal model for Krabbe disease, is impaired in peripheral axons and is accompanied by a progressive reduction in the abundance and phosphorylation of the three neurofilament (NF) subunits. These changes correlate with an increase in the density of NFs per cross-sectional area in numerous mutant peripheral axons and abnormal increases in the activity of two serine/threonine phosphatases (PP1 and PP2A) in mutant tissue. Similarly, acutely isolated mutant cortical neurons show abnormal phosphorylation of NFs. Psychosine, the neurotoxin accumulated in Krabbe disease, was sufficient to induce abnormal dephosphorylation of NF subunits in a normal motor neuron cell line as well as in acutely isolated normal cortical neurons. This in vitro effect was mediated by PP1 and PP2A, which specifically dephosphorylated NFs. These results demonstrate that the reduced caliber observed in some axons in Krabbe disease involves abnormal dephosphorylation of NFs. We propose that a psychosine-driven pathogenic mechanism through deregulated phosphotransferase activities may be involved in this process.
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Shea TB, Lee S. Neurofilament phosphorylation regulates axonal transport by an indirect mechanism: a merging of opposing hypotheses. Cytoskeleton (Hoboken) 2011; 68:589-95. [PMID: 21990272 DOI: 10.1002/cm.20535] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 09/22/2011] [Indexed: 01/22/2023]
Abstract
Neurofilaments (NFs) are among the most abundant constituents of the axonal cytoskeleton. NFs consist of four subunits, termed NF-H, NF-M and NF-L, corresponding to heavy, medium and light in reference to their molecular mass and α-internexin. Phosphorylation of the C-terminal "sidearms" of NF-H and NF-M regulates the ability of NFs to form a cytoskeletal lattice that supports the mature axon. C-terminal phosphorylation events have classically been considered to regulate NF axonal transport. By contrast, studies demonstrating that NF axonal transport was not accelerated following sidearm deletion provided evidence that phosphorylation does not regulate NF transport. Herein, we demonstrate how comparison of transport and distribution of differentially phosphorylated NFs along axons identify common ground between these hypotheses and may resolve this controversy.
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Affiliation(s)
- Thomas B Shea
- Department of Biological Sciences, Center for Cellular Neurobiology and Neurodegeneration Research, University of Massachusetts-Lowell, Lowell, Massachusetts 01854, USA.
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Tang YS, Khan RA, Zhang Y, Xiao S, Wang M, Hansen DK, Jayaram HN, Antony AC. Incrimination of heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1) as a candidate sensor of physiological folate deficiency. J Biol Chem 2011; 286:39100-15. [PMID: 21930702 DOI: 10.1074/jbc.m111.230938] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism underlying the sensing of varying degrees of physiological folate deficiency, prior to adaptive optimization of cellular folate uptake through the translational up-regulation of folate receptors (FR) is unclear. Because homocysteine, which accumulates intracellularly during folate deficiency, stimulated interactions between heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1) and an 18-base FR-α mRNA cis-element that led to increased FR biosynthesis and net up-regulation of FR at cell surfaces, hnRNP-E1 was a plausible candidate sensor of folate deficiency. Accordingly, using purified components, we evaluated the physiological basis whereby L-homocysteine triggered these RNA-protein interactions to stimulate FR biosynthesis. L-homocysteine induced a concentration-dependent increase in RNA-protein binding affinity throughout the range of physiological folate deficiency, which correlated with a proportionate increase in translation of FR in vitro and in cultured human cells. Targeted reduction of newly synthesized hnRNP-E1 proteins by siRNA to hnRNP-E1 mRNA reduced both constitutive and L-homocysteine-induced rates of FR biosynthesis. Furthermore, L-homocysteine covalently bound hnRNP-E1 via multiple protein-cysteine-S-S-homocysteine mixed disulfide bonds within K-homology domains known to interact with mRNA. These data suggest that a concentration-dependent, sequential disruption of critical cysteine-S-S-cysteine bonds by covalently bound L-homocysteine progressively unmasks an underlying RNA-binding pocket in hnRNP-E1 to optimize interaction with FR-α mRNA cis-element preparatory to FR up-regulation. Collectively, such data incriminate hnRNP-E1 as a physiologically relevant, sensitive, cellular sensor of folate deficiency. Because diverse mammalian and viral mRNAs also interact with this RNA-binding domain with functional consequences to their protein expression, homocysteinylated hnRNP-E1 also appears well positioned to orchestrate a novel, nutrition-sensitive (homocysteine-responsive), posttranscriptional RNA operon in folate-deficient cells.
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Affiliation(s)
- Ying-Sheng Tang
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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Stevenson W, Chang R, Gebremichael Y. Phosphorylation-mediated conformational changes in the mouse neurofilament architecture: insight from a neurofilament brush model. J Mol Biol 2010; 405:1101-18. [PMID: 21134382 DOI: 10.1016/j.jmb.2010.11.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 11/08/2010] [Accepted: 11/11/2010] [Indexed: 11/24/2022]
Abstract
Neurofilaments (NFs) are important cytoskeletal filaments that consist of long flexible C-terminal tails that are abundant with charges. The tails attain additional negative charges through serine phosphorylation of Lys-Ser-Pro (KSP) repeat motifs that are particularly found in neurofilament heavy (NF-H) and neurofilament medium (NF-M) proteins. These side-arm protrusions mediate the interaction between neighboring filaments and maintain axonal diameter. However, the precise role of NF proteins and their phosphorylation in regulating interfilament distances and axonal diameter still remains unclear. In this regard, a recent gene replacement study revealed that the phosphorylation of mouse NF-M KSP repeats does not affect axonal cytoarchitecture, challenging the conventional viewpoint on the role of NF phosphorylation. To better understand the effect of phosphorylation, particularly NF-M phosphorylation, we applied a computational method to reveal phosphorylation-mediated conformational changes in mouse NF architecture. We employed a three-dimensional sequence-based coarse-grained NF brush model to perform Monte Carlo simulations of mouse NF by using the sequence and stoichiometry of mouse NF proteins. Our result shows that the phosphorylation of mouse NF-M does not change the radial extension of NF-M side arms under a salt-free condition and in ionic solution, highlighting a structural factor that supports the notion that NF-M KSP phosphorylation has no effect on the axonal diameter of mouse. On the other hand, significant phosphorylation-mediated conformational changes were found in NF-H side arms under the salt-free condition, while the changes in ionic solution are not significant. However, NF-H side arms are found at the periphery of mouse NF architecture, implying a role in linking neighboring filaments.
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Affiliation(s)
- William Stevenson
- Department of Biomedical Engineering, Wayne State University, Detroit, MI 48201, USA
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