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Spencer PS. Neuroprotein Targets of γ-Diketone Metabolites of Aliphatic and Aromatic Solvents That Induce Central-Peripheral Axonopathy. Toxicol Pathol 2020; 48:411-421. [PMID: 32162603 DOI: 10.1177/0192623320910960] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Peripheral neuropathy associated with chronic occupational and deliberate overexposure to neurotoxic organic solvents results from axonal degeneration in the central and peripheral nervous system. Human and experimental studies show that axonopathy is triggered by the action of neuroprotein-reactive γ-diketone metabolites formed from exposure to certain aliphatic solvents (n-hexane, 2-hexanone) and aromatic compounds (1,2-diethylbenzene, 1,2-4-triethylbenzene, 6-acetyl-1,1,4,4-tetramethyl-7-ethyl-1,2,3,4-tetralin). Neuroprotein susceptibility is related primarily to their differential content of lysine, the ∊-amino group of which is targeted by γ-diketones. Specific neuroprotein targets have been identified, and the sequence of molecular mechanisms leading to axonal pathology has been illuminated. While occupational n-hexane neuropathy continues to be reported, lessons learned from its experimental study may have relevance to other causes of peripheral neuropathy, including those associated with aging and diabetes mellitus.
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Affiliation(s)
- Peter S Spencer
- Oregon Institute of Occupational Health Sciences and Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR, USA
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2
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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: 419] [Impact Index Per Article: 59.9] [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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3
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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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4
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Order and disorder in intermediate filament proteins. FEBS Lett 2015; 589:2464-76. [PMID: 26231765 DOI: 10.1016/j.febslet.2015.07.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/21/2015] [Accepted: 07/22/2015] [Indexed: 11/20/2022]
Abstract
Intermediate filaments (IFs), important components of the cytoskeleton, provide a versatile, tunable network of self-assembled proteins. IF proteins contain three distinct domains: an α-helical structured rod domain, flanked by intrinsically disordered head and tail domains. Recent studies demonstrated the functional importance of the disordered domains, which differ in length and amino-acid sequence among the 70 different human IF genes. Here, we investigate the biophysical properties of the disordered domains, and review recent findings on the interactions between them. Our analysis highlights key components governing IF functional roles in the cytoskeleton, where the intrinsically disordered domains dictate protein-protein interactions, supramolecular assembly, and macro-scale order.
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Pesaresi M, Soon-Shiong R, French L, Kaplan DR, Miller FD, Paus T. Axon diameter and axonal transport: In vivo and in vitro effects of androgens. Neuroimage 2015; 115:191-201. [PMID: 25956809 DOI: 10.1016/j.neuroimage.2015.04.048] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/23/2015] [Accepted: 04/24/2015] [Indexed: 01/05/2023] Open
Abstract
Testosterone is a sex hormone involved in brain maturation via multiple molecular mechanisms. Previous human studies described age-related changes in the overall volume and structural properties of white matter during male puberty. Based on this work, we have proposed that testosterone may induce a radial growth of the axon and, possibly, modulate axonal transport. In order to determine whether this is the case we have used two different experimental approaches. With electron microscopy, we have evaluated sex differences in the structural properties of axons in the corpus callosum (splenium) of young rats, and tested consequences of castration carried out after weaning. Then we examined in vitro the effect of the non-aromatizable androgen Mibolerone on the structure and bidirectional transport of wheat-germ agglutinin vesicles in the axons of cultured sympathetic neurons. With electron microscopy, we found robust sex differences in axonal diameter (males>females) and g ratio (males>females). Removal of endogenous testosterone by castration was associated with lower axon diameter and lower g ratio in castrated (vs. intact) males. In vitro, Mibolerone influenced the axonal transport in a time- and dose-dependent manner, and increased the axon caliber as compared with vehicle-treated neurons. These findings are consistent with the role of testosterone in shaping the axon by regulating its radial growth, as predicted by the initial human studies.
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Affiliation(s)
- M Pesaresi
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada
| | - R Soon-Shiong
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada
| | - L French
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada
| | - D R Kaplan
- Program in Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - F D Miller
- Program in Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - T Paus
- Rotman Research Institute, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada.
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Lavrnja I, Savic D, Parabucki A, Dacic S, Laketa D, Pekovic S, Stojiljkovic M. Effect of stab injury in the rat cerebral cortex on temporal pattern of expression of neuronal cytoskeletal proteins: an immunohistochemical study. Acta Histochem 2015; 117:155-62. [PMID: 25592752 DOI: 10.1016/j.acthis.2014.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 12/01/2014] [Accepted: 12/02/2014] [Indexed: 12/20/2022]
Abstract
Compelling evidence now points to the critical role of the cytoskeleton in neurodegeneration. In the present study, using an immunohistochemical approach, we have shown that cortical stab injury (CSI) in adult Wistar rats significantly affects temporal pattern of expression of neurofilament proteins (NFs), a major cytoskeleton components of neurons, and microtubule-associated proteins (MAP2). At 3 days post-injury (dpi) most of the NFs immunoreactivity was found in pyknotic neurons and in fragmentized axonal processes in the perilesioned cortex. These cytoskeletal alterations became more pronounced by 10dpi. At the subcellular level CSI also showed significant impact on NFs and MAP-2 expression. Thus, at 3dpi most of the dendrites disappeared, while large neuronal somata appeared like open circles pointing to membrane disintegration. Conversely, at 10dpi neuronal perikarya and a few new apical dendrites were strongly labeled. Since aberrant NF phosphorylation is a pathological hallmark of many human neurodegenerative disorders, as well as is found after stressor stimuli, the present results shed light into the expression of neurofilaments after the stab brain injury.
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Affiliation(s)
- Irena Lavrnja
- Department of Neurobiology, Institute for Biological Research "Sinisa Stankovic" University of Belgrade, Belgrade, Serbia.
| | - Danijela Savic
- Department of Neurobiology, Institute for Biological Research "Sinisa Stankovic" University of Belgrade, Belgrade, Serbia
| | - Ana Parabucki
- Department of Neurobiology, Institute for Biological Research "Sinisa Stankovic" University of Belgrade, Belgrade, Serbia
| | - Sanja Dacic
- Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Danijela Laketa
- Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Sanja Pekovic
- Department of Neurobiology, Institute for Biological Research "Sinisa Stankovic" University of Belgrade, Belgrade, Serbia
| | - Mirjana Stojiljkovic
- Department of Neurobiology, Institute for Biological Research "Sinisa Stankovic" University of Belgrade, Belgrade, Serbia
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7
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Laser-Azogui A, Kornreich M, Malka-Gibor E, Beck R. Neurofilament assembly and function during neuronal development. Curr Opin Cell Biol 2015; 32:92-101. [PMID: 25635910 DOI: 10.1016/j.ceb.2015.01.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 01/06/2015] [Accepted: 01/09/2015] [Indexed: 02/06/2023]
Abstract
Studies on the assembly of neuronal intermediate filaments (IFs) date back to the early work of Alzheimer. Developing neurons express a series of IF proteins, sequentially, at distinct stages of mammalian cell differentiation. This correlates with altered morphologies during the neuronal development, including axon outgrowth, guidance and conductivity. Importantly, neuronal IFs that fail to properly assemble into a filamentous network are a hallmark of neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's, and Parkinson's disease. Traditional structural methodologies fail to fully describe neuronal IF assembly, interactions and resulting function due to IFs structural plasticity, particularly in their C-terminal domains. We review here current progress in the field of neuronal-specific IFs, a dominant component affecting the cytoskeletal structure and function of neurons.
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Affiliation(s)
- Adi Laser-Azogui
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Micha Kornreich
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Eti Malka-Gibor
- Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Roy Beck
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel.
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8
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Mechanisms of Pelvic Organ Cross-Talk: 2. Impact of Colorectal Distention on Afferent Nerve Activity of the Rat Bladder. J Urol 2013; 190:1123-30. [DOI: 10.1016/j.juro.2013.03.079] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2013] [Indexed: 12/30/2022]
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9
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Gentil BJ, Mushynski WE, Durham HD. Heterogeneity in the properties of NEFL mutants causing Charcot-Marie-Tooth disease results in differential effects on neurofilament assembly and susceptibility to intervention by the chaperone-inducer, celastrol. Int J Biochem Cell Biol 2013; 45:1499-508. [PMID: 23618875 DOI: 10.1016/j.biocel.2013.04.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 04/05/2013] [Indexed: 11/25/2022]
Abstract
Aberrant aggregation of neurofilament proteins is a common feature of neurodegenerative diseases. For example, neurofilament light protein (NEFL) mutants causing Charcot-Marie-Tooth disease induce misassembly of neurofilaments. This study demonstrated that mutations in different functional domains of NEFL have different effects on filament assembly and susceptibility to interventions to restore function. The mouse NEFL mutants, NEFL(Q333P) and NEFL(P8R), exhibited different assembly properties in SW13-cells, cells lacking endogenous intermediate filaments, indicating different consequences of these mutations on the biochemical properties of NEFL. The p.Q333P mutation caused reversible misfolding of the protein. NEFL(Q333P) could be refolded and form coil-coiled dimers, in vitro using chaotropic agent, and in cultured cells by induction of HSPA1 and HSPB1. Celastrol, an inducer of chaperone proteins, induced HSPA1 expression in motor neurons and prevented the formation of neurofilament inclusions and mitochondrial shortening induced by expression of NEFL(Q333P), but not in sensory neurons. Conversely, celastrol had a protective effect against the toxicity of NEFL(P8R), a mutant which is sensitive to HSBP1 but not HSPA1 chaperoning, only in large-sized sensory neurons, not in motor neurons. Importantly, sensory and motor neurons do not respond identically to celastrol and different chaperones are upregulated by the same treatment. Thus, effective therapy of CMT not only depends on the identity of the mutated gene, but the consequences of the specific mutation on the properties of the protein and the neuronal population targeted.
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Affiliation(s)
- Benoit J Gentil
- Department of Neurology/Neurosurgery and Montreal Neurological Institute, Montreal, QC, Canada.
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10
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Jayanthi L, Stevenson W, Kwak Y, Chang R, Gebremichael Y. Conformational properties of interacting neurofilaments: Monte Carlo simulations of cylindrically grafted apposing neurofilament brushes. J Biol Phys 2012; 39:343-62. [PMID: 23860913 DOI: 10.1007/s10867-012-9293-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 11/04/2012] [Indexed: 10/27/2022] Open
Abstract
Neurofilaments are essential cytoskeletal filaments that impart mechanical stability to axons. They are mostly assembled from three neurofilament proteins that form the core of the filament and its sidearms. Adjacent neurofilaments interact with each other through their apposing sidearms and attain unique conformations depending on the ionic condition, phosphorylation state, and interfilament separations. To understand the conformational properties of apposing sidearms under various conditions and gain insight into interfilament interactions, we performed Monte Carlo simulations of neurofilament pairs. We employed a sequence-based coarse-grained model of apposing NF sidearms that are end-tethered to cylindrical geometries according to the stoichiometry of the three neurofilament subunits. Monte Carlo simulations were conducted under different conditions such as phosphorylation state, ionic condition, and interfilament separations. Under salt-free conditions, apposing sidearms are found to adopt mutually excluding stretched but bent away conformations that are reminiscent of a repulsive type of interaction. Under physiological conditions, apposing sidearms are found to be in a coiled conformation, suggesting a short-range steric repulsive type of interaction. Increased sidearm mutual interpenetration and a simultaneous decrease in the individual brush heights were observed as the interfilament separation was reduced from 60 to 40 nm. The observed conformations suggest entropic interaction as a likely mechanism for sidearm-mediated interfilament interactions under physiological conditions.
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Affiliation(s)
- Lakshmi Jayanthi
- Department of Biomedical Engineering, Wayne State University, Detroit, MI 48201, USA
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11
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Barry DM, Stevenson W, Bober BG, Wiese PJ, Dale JM, Barry GS, Byers NS, Strope JD, Chang R, Schulz DJ, Shah S, Calcutt NA, Gebremichael Y, Garcia ML. Expansion of neurofilament medium C terminus increases axonal diameter independent of increases in conduction velocity or myelin thickness. J Neurosci 2012; 32:6209-19. [PMID: 22553027 PMCID: PMC3363292 DOI: 10.1523/jneurosci.0647-12.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 03/13/2012] [Accepted: 03/17/2012] [Indexed: 12/30/2022] Open
Abstract
Maturation of the peripheral nervous system requires specification of axonal diameter, which, in turn, has a significant influence on nerve conduction velocity. Radial axonal growth initiates with myelination, and is dependent upon the C terminus of neurofilament medium (NF-M). Molecular phylogenetic analysis in mammals suggested that expanded NF-M C termini correlated with larger-diameter axons. We used gene targeting and computational modeling to test this new hypothesis. Increasing the length of NF-M C terminus in mice increased diameter of motor axons without altering neurofilament subunit stoichiometry. Computational modeling predicted that an expanded NF-M C terminus extended farther from the neurofilament core independent of lysine-serine-proline (KSP) phosphorylation. However, expansion of NF-M C terminus did not affect the distance between adjacent neurofilaments. Increased axonal diameter did not increase conduction velocity, possibly due to a failure to increase myelin thickness by the same proportion. Failure of myelin to compensate for larger axonal diameters suggested a lack of plasticity during the processes of myelination and radial axonal growth.
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Affiliation(s)
- Devin M. Barry
- Department of Biological Sciences and
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - William Stevenson
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan 48201
| | | | | | - Jeffrey M. Dale
- Department of Biological Sciences and
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Garet S. Barry
- Department of Biological Sciences and
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Nathan S. Byers
- Department of Biological Sciences and
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Jonathan D. Strope
- Department of Biological Sciences and
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Rakwoo Chang
- Department of Chemistry, Kwangwoon University, Seoul 139-701, Republic of Korea
| | | | | | - Nigel A. Calcutt
- Pathology, University of California, San Diego, La Jolla, California 92093, and
| | | | - Michael L. Garcia
- Department of Biological Sciences and
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
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