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Wang M, Lassers SB, Vakilna YS, Mander BA, Tang WC, Brewer GJ. Spindle oscillations in communicating axons within a reconstituted hippocampal formation are strongest in CA3 without thalamus. Sci Rep 2024; 14:8384. [PMID: 38600114 PMCID: PMC11006914 DOI: 10.1038/s41598-024-58002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
Spindle-shaped waves of oscillations emerge in EEG scalp recordings during human and rodent non-REM sleep. The association of these 10-16 Hz oscillations with events during prior wakefulness suggests a role in memory consolidation. Human and rodent depth electrodes in the brain record strong spindles throughout the cortex and hippocampus, with possible origins in the thalamus. However, the source and targets of the spindle oscillations from the hippocampus are unclear. Here, we employed an in vitro reconstruction of four subregions of the hippocampal formation with separate microfluidic tunnels for single axon communication between subregions assembled on top of a microelectrode array. We recorded spontaneous 400-1000 ms long spindle waves at 10-16 Hz in single axons passing between subregions as well as from individual neurons in those subregions. Spindles were nested within slow waves. The highest amplitudes and most frequent occurrence suggest origins in CA3 neurons that send feed-forward axons into CA1 and feedback axons into DG. Spindles had 50-70% slower conduction velocities than spikes and were not phase-locked to spikes suggesting that spindle mechanisms are independent of action potentials. Therefore, consolidation of declarative-cognitive memories in the hippocampus may be separate from the more easily accessible consolidation of memories related to thalamic motor function.
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Affiliation(s)
- Mengke Wang
- Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
| | - Samuel B Lassers
- Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
| | - Yash S Vakilna
- Texas Institute of Restorative Neurotechnologies (TIRN), The University of Texas Health Science Center (UTHealth), Houston, TX, 77030, USA
| | - Bryce A Mander
- Center for Neurobiology of Learning and Memory and MIND Center, University of California, Irvine, CA, 92697, USA
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA, 92868, USA
| | - William C Tang
- Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
| | - Gregory J Brewer
- Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA.
- Center for Neurobiology of Learning and Memory and MIND Center, University of California, Irvine, CA, 92697, USA.
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, 92697, USA.
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2
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Dithmar S, Zare A, Salehi S, Briese M, Sendtner M. hnRNP R regulates mitochondrial movement and membrane potential in axons of motoneurons. Neurobiol Dis 2024; 193:106454. [PMID: 38408684 DOI: 10.1016/j.nbd.2024.106454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/12/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024] Open
Abstract
Axonal mitochondria defects are early events in the pathogenesis of motoneuron disorders such as spinal muscular atrophy and amyotrophic lateral sclerosis. The RNA-binding protein hnRNP R interacts with different motoneuron disease-related proteins such as SMN and TDP-43 and has important roles in axons of motoneurons, including axonal mRNA transport. However, whether hnRNP R also modulates axonal mitochondria is currently unknown. Here, we show that axonal mitochondria exhibit altered function and motility in hnRNP R-deficient motoneurons. Motoneurons lacking hnRNP R show decreased anterograde and increased retrograde transport of mitochondria in axons. Furthermore, hnRNP R-deficiency leads to mitochondrial hyperpolarization, caused by decreased complex I and reversed complex V activity within the respiratory chain. Taken together, our data indicate a role for hnRNP R in regulating transport and maintaining functionality of axonal mitochondria in motoneurons.
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Affiliation(s)
- Sophia Dithmar
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Abdolhossein Zare
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Saeede Salehi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
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3
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Mishra SK, Tiwari SP. Bioenergetics of Axon Integrity and Its Regulation by Oligodendrocytes and Schwann Cells. Mol Neurobiol 2024:10.1007/s12035-024-03950-x. [PMID: 38252382 DOI: 10.1007/s12035-024-03950-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 01/09/2024] [Indexed: 01/23/2024]
Abstract
Axons are long slender portions of neurons that transmit electrical impulses to maintain proper physiological functioning. Axons in the central nervous system (CNS) and peripheral nervous system (PNS) do not exist in isolation but are found to form a complex association with their surrounding glial cells, oligodendrocytes and Schwann cells. These cells not only myelinate them for faster nerve impulse conduction but are also known to provide metabolic support. Due to their incredible length, continuous growth, and distance from the cell body (where major energy synthesis takes place), axons are in high energetic demand. The stability and integrity of axons have long been associated with axonal energy levels. The current mini-review is thus focused on how axons accomplish their high energetic requirement in a cell-autonomous manner and how the surrounding glial cells help them in maintaining their integrity by fulfilling their energy demands (non-cell autonomous trophic support). The concept that adjacent glial cells (oligodendrocytes and Schwann cells) provide trophic support to axons and assist them in maintaining their integrity comes from the conditional knockout research and the studies in which the metabolic pathways controlling metabolism in these glial cells are modulated and its effect on axonal integrity is evaluated. In the later part of the mini-review, the current knowledge of axon-glial metabolic coupling during various neurodegenerative conditions was discussed, along with the potential lacunae in our current understanding of axon-glial metabolic coupling.
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Affiliation(s)
- Sandeep K Mishra
- Institute for Myelin and Glia Exploration, University at Buffalo, Buffalo, NY, 14203, USA.
- Faculty of Pharmacy, Kalinga University, Raipur, (C.G.), 492101, India.
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Langerscheidt F, Bell-Simons M, Zempel H. Differentiating SH-SY5Y Cells into Polarized Human Neurons for Studying Endogenous and Exogenous Tau Trafficking: Four Protocols to Obtain Neurons with Noradrenergic, Dopaminergic, and Cholinergic Properties. Methods Mol Biol 2024; 2754:521-532. [PMID: 38512687 DOI: 10.1007/978-1-0716-3629-9_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Pathological alterations of the neuronal Tau protein are characteristic for many neurodegenerative diseases, called tauopathies. To investigate the underlying mechanisms of tauopathies, human neuronal cell models are required to study Tau physiology and pathology in vitro. Primary rodent neurons are an often used model for studying Tau, but rodent Tau differs in sequence, splicing, and aggregation propensity, and rodent neuronal physiology cannot be compared to humans. Human-induced pluripotent stem cell (hiPSC)-derived neurons are expensive and time-consuming. Therefore, the human neuroblastoma SH-SY5Y cell line is a commonly used cell model in neuroscience as it combines convenient handling and low costs with the advantages of human-derived cells. Since naïve SH-SY5Y cells show little similarity to human neurons and almost no Tau expression, differentiation is necessary to obtain human-like neurons for studying Tau protein-related aspects of health and disease. As they express in principle all six Tau isoforms seen in the human brain, differentiated SH-SY5Y-derived neurons are suitable for investigating the human microtubule-associated protein Tau and, for example, its sorting and trafficking. Here, we describe and discuss a general cultivation procedure as well as four differentiation methods to obtain SH-SY5Y-derived neurons resembling noradrenergic, dopaminergic, and cholinergic properties, based on the treatment with retinoic acid (RA), brain-derived neurotrophic factor (BDNF), and 12-O-tetrade canoylphorbol-13-acetate (TPA). TPA and RA-/TPA-based protocols achieve differentiation efficiencies of 40-50% after 9 days of treatment. The highest differentiation efficiency (~75%) is accomplished by a combination of RA and BDNF; treatment only with RA is the most time-efficient method as ~50% differentiated cells can be obtained already after 7 days.
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Affiliation(s)
- Felix Langerscheidt
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Department of Chemistry and Biotechnology, Aachen University of Applied Sciences, Campus Jülich, Jülich, Germany
| | - Michael Bell-Simons
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Hans Zempel
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
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5
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Canepari M, Ross WN. Spatial and temporal aspects of neuronal calcium and sodium signals measured with low-affinity fluorescent indicators. Pflugers Arch 2024; 476:39-48. [PMID: 37798555 DOI: 10.1007/s00424-023-02865-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/12/2023] [Accepted: 09/21/2023] [Indexed: 10/07/2023]
Abstract
Low-affinity fluorescent indicators for Ca2+ or Na+ allow measuring the dynamics of intracellular concentration of these ions with little perturbation from physiological conditions because they are weak buffers. When using synthetic indicators, which are small molecules with fast kinetics, it is also possible to extract spatial and temporal information on the sources of ion transients, their localization, and their disposition. This review examines these important aspects from the biophysical point of view, and how they have been recently exploited in neurophysiological studies. We first analyze the environment where Ca2+ and Na+ indicators are inserted, highlighting the interpretation of the two different signals. Then, we address the information that can be obtained by analyzing the rising phase and the falling phase of the Ca2+ and Na+ transients evoked by different stimuli, focusing on the kinetics of ionic currents and on the spatial interpretation of these measurements, especially on events in axons and dendritic spines. Finally, we suggest how Ca2+ or Na+ imaging using low-affinity synthetic fluorescent indicators can be exploited in future fundamental or applied research.
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Affiliation(s)
- Marco Canepari
- LIPhy, CNRS, Univ. Grenoble Alpes, F-38000, Grenoble, France.
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France.
- Institut National de la Santé et Recherche Médicale, Paris, France.
| | - William N Ross
- Department of Physiology, New York Medical College, Valhalla, NY, 10595, USA
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Kehrer A, Engelmann S, Knoedler L, Klein SM, Anker AM, Heidekrueger P, Tamm E, Bleys RL, Prantl L, Ruewe M. The masseteric nerve for facial reanimation: Macroscopic and histomorphometric characteristics in 106 human cadavers and comparison of axonal ratio with recipient nerves. J Craniomaxillofac Surg 2024; 52:8-13. [PMID: 38129186 DOI: 10.1016/j.jcms.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 09/05/2023] [Indexed: 12/23/2023] Open
Abstract
Peripheral facial palsy causes severe impairments. Sufficient axonal load is critical for adequate functional outcomes in reanimation procedures. The aim of our study was to attain a better understanding of the anatomy of the masseteric nerve as a donor, in order to optimize neurotization procedures. Biopsies were obtained from 106 hemifaces of fresh frozen human cadavers. Histological cross-sections were fixed, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. Of the 154 evaluated branches, 74 specimens were of the main trunk (MT), 40 of the anterior branch (AB), and 38 of the descending branch (DB), while two halves of one cadaver featured an additional branch. The MT showed a diameter of 1.4 ± 0.41 mm (n = 74) with 2213 ± 957 axons (n = 55). The AB diameter was 0.9 ± 0.33 mm (n = 40) with 725 ± 714 axons (n = 30). The DB diameter was 1.15 ± 0.34 mm (n = 380) with 1562 ± 926 axons (n = 30). The DB demonstrated a high axonal capacity - valuable for nerve transfers or muscle transplants. Our findings should facilitate a balanced selection of axonal load, and are potentially helpful in achieving more predictable results while preserving masseter muscle function.
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Affiliation(s)
- Andreas Kehrer
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany.
| | - Simon Engelmann
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Leonard Knoedler
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Silvan M Klein
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Alexandra M Anker
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Paul Heidekrueger
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Ernst Tamm
- Department of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Ronald Law Bleys
- Department of Anatomy, University Medical Center (UMC) Utrecht, Utrecht, Netherlands
| | - Lukas Prantl
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Marc Ruewe
- Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany
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Dogan EO, Bouley J, Zhong J, Harkins AL, Keeler AM, Bosco DA, Brown RH, Henninger N. Genetic ablation of Sarm1 attenuates expression and mislocalization of phosphorylated TDP-43 after mouse repetitive traumatic brain injury. Acta Neuropathol Commun 2023; 11:206. [PMID: 38124145 PMCID: PMC10731794 DOI: 10.1186/s40478-023-01709-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
Traumatic brain injury (TBI), particularly when moderate-to-severe and repetitive, is a strong environmental risk factor for several progressive neurodegenerative disorders. Mislocalization and deposition of transactive response DNA binding protein 43 (TDP-43) has been reported in both TBI and TBI-associated neurodegenerative diseases. It has been hypothesized that axonal pathology, an early event after TBI, may promote TDP-43 dysregulation and serve as a trigger for neurodegenerative processes. We sought to determine whether blocking the prodegenerative Sarm1 (sterile alpha and TIR motif containing 1) axon death pathway attenuates TDP-43 pathology after TBI. We subjected 111 male Sarm1 wild type, hemizygous, and knockout mice to moderate-to-severe repetitive TBI (rTBI) using a previously established injury paradigm. We conducted serial neurological assessments followed by histological analyses (NeuN, MBP, Iba-1, GFAP, pTDP-43, and AT8) at 1 month after rTBI. Genetic ablation of the Sarm1 gene attenuated the expression and mislocalization of phosphorylated TDP-43 (pTDP-43) and accumulation of pTau. In addition, Sarm1 knockout mice had significantly improved cortical neuronal and axonal integrity, functional deficits, and improved overall survival after rTBI. In contrast, removal of one Sarm1 allele delayed, but did not prevent, neurological deficits and neuroaxonal loss. Nevertheless, Sarm1 haploinsufficient mice showed significantly less microgliosis, pTDP-43 pathology, and pTau accumulation when compared to wild type mice. These data indicate that the Sarm1-mediated prodegenerative pathway contributes to pathogenesis in rTBI including the pathological accumulation of pTDP-43. This suggests that anti-Sarm1 therapeutics are a viable approach for preserving neurological function after moderate-to-severe rTBI.
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Affiliation(s)
- Elif O Dogan
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
| | - James Bouley
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
| | - Jianjun Zhong
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ashley L Harkins
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
- Graduate Program in Neuroscience, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA
- Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Allison M Keeler
- Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
- Department of Pediatrics, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
- NeuroNexus Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Daryl A Bosco
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
| | - Nils Henninger
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA.
- Department of Psychiatry, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA.
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8
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Andreasen M, Nedergaard S. Effects of carbonic anhydrase activity on the excitability of hippocampal axons during high-frequency firing. Brain Res 2023; 1821:148604. [PMID: 37748571 DOI: 10.1016/j.brainres.2023.148604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/24/2023] [Accepted: 09/22/2023] [Indexed: 09/27/2023]
Abstract
Epileptic activity is known to cause a lowering of intraneuronal pH, which has been suggested to serve as a feedback signal to terminate seizures. The mechanism of such signaling is unclear, but likely involves an altered function of several types of ligand- and voltage-gated channels in postsynaptic membranes caused by increasing cytosolic and extracellular [H+]. In addition, axonal conduction properties may be altered by endogenous pH signals, but this has not been investigated. In the present study, we have recorded the axonal compound action potential (fiber volley) in hippocampal slices in the presence of glutamatergic and GABAergic antagonists. During high-frequency stimulation (HFS) of the Schaffer collaterals, the fiber volley was depressed and its latency from stimulus to peak increased. In the CA1 stratum radiatum these changes were enhanced when the carbonic anhydrase inhibitor acetazolamide (1 mM) was co-perfused. The enhancing effect of acetazolamide was absent after lowering of [Ca2+] in the perfusion medium. Acetazolamide had no detectable effect on HFS-evoked fiber volleys recorded from a more proximal site along the Schaffer collaterals (at the CA2-CA3 border) or from axons in the alveus of CA1. Intracellular acidification imposed by washout of NH4Cl (5 mM) had qualitatively similar effects on fiber volleys evoked at low frequency as those observed with acetazolamide during HFS in CA1 stratum radiatum. The results suggest that carbonic anhydrase-dependent pH regulation counteracts activity-induced reduction of the excitability of Schaffer collateral axons in CA1. A possible influence from local synaptic terminals on this effect is discussed.
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Affiliation(s)
- Mogens Andreasen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Steen Nedergaard
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
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9
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Funakoshi M, Araki T. Mechanism of initiation and regulation of axonal degeneration with special reference to NMNATs and Sarm1. Neurosci Res 2023; 197:3-8. [PMID: 34767875 DOI: 10.1016/j.neures.2021.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 11/01/2021] [Indexed: 10/19/2022]
Abstract
Axonal degeneration is observed in a variety of contexts in both the central and peripheral nervous systems. Pathological signaling to regulate the progression of axonal degeneration has long been studied using Wallerian degeneration, the prototypical axonal degradation observed after injury, as a representative model. Understanding metabolism of nicotinamide adenine dinucleotide (NAD+) and the functional regulation of Sarm1 has generated great progress in this field, but there are a number of remaining questions. Here, in this short review, we describe our current understanding of the axonal degeneration mechanism, with special reference to the biology related to wlds mice and Sarm1. Furthermore, variations of axonal degeneration initiation are discussed in order to address the remaining questions needed for mechanistic clarification.
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Affiliation(s)
- Masabumi Funakoshi
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan
| | - Toshiyuki Araki
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.
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10
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You M, Xing H, Yan M, Zhang J, Chen J, Chen Y, Liu X, Zhu J. Schwann Cell-Derived Exosomes Ameliorate Paclitaxel-Induced Peripheral Neuropathy Through the miR-21-Mediated PTEN Signaling Pathway. Mol Neurobiol 2023; 60:6840-6851. [PMID: 37498480 DOI: 10.1007/s12035-023-03488-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/05/2023] [Indexed: 07/28/2023]
Abstract
Paclitaxel-induced peripheral neuropathy (PIPN) is a neurological disorder resulting from paclitaxel (PTX) treatment for cancer patients. There are currently no drugs available that can definitively prevent or treat PIPN. Exosomes are cell-secreted nanoscale vesicles that mediate communication between neurons and glial cells. We found that Schwann cell-derived exosomes (SC-EXOs) robustly improved PIPN both in vitro and in vivo. In vivo studies showed that SC-EXOs were able to alleviate PTX-induced mechanical nociceptive sensitization in rats. Pathomorphological analysis showed that SC-EXOs ameliorated PTX-induced plantar intraepidermal nerve fiber loss and dorsal root ganglion (DRG) injury. Additionally, the results of in vitro studies showed that SC-EXOs had significant protective effects on the DRG cells damaged by PTX, and did not affect the antitumor effect of PTX against Hela cells. Further, mechanism research revealed that SC-EXOs promoted axonal regeneration and protected damaged neurons by upregulating miR-21 to repress the phosphatase and tensin homolog (PTEN) pathway, which could improve PIPN. Taken together, these findings suggest that SC-EXOs ameliorate PTX-induced peripheral neuropathy via the miR-21-mediated PTEN signaling pathway, which provides a novel strategy for the treatment of PIPN.
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Affiliation(s)
- Min You
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China
| | - Haizhu Xing
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China
| | - Ming Yan
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China
| | - Jie Zhang
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China
| | - Jiayi Chen
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China
| | - Yang Chen
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China
| | - Xiaoli Liu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China.
| | - Jing Zhu
- Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, People's Republic of China.
- Department of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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11
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Tüfekci KK, Kaplan AA, Kaya A, Alrafiah A, Altun G, Aktaş A, Kaplan S. The potential protective effects of melatonin and omega-3 on the male rat optic nerve exposed to 900 MHz electromagnetic radiation during the prenatal period. Int J Neurosci 2023; 133:1424-1436. [PMID: 37712630 DOI: 10.1080/00207454.2023.2259078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/17/2023] [Accepted: 09/09/2023] [Indexed: 09/16/2023]
Abstract
BACKGROUND Due to children and adolescents' widespread use of electronic devices, researchers have focused on pre-and early postnatal electromagnetic field (EMF) exposure. However, little is known about the effects of EMF exposure on the optic nerve. The aim of study was to investigate the changes occurring in the optic nerve and the protective effects of melatonin (mel) and omega 3 (ω-3) in rats. METHODS Thirty-five pregnant rats were divided into seven groups, Cont, Sham, EMF, EMF + melatonin (EMF + Mel), EMF + ω3, Mel, and ω3. The EMF groups were exposed to 900 megahertz (MHz) EMF daily for two hours during pregnancy. After the experiment, the right optic nerve of each offspring rat was removed and fixed in glutaraldehyde. Thin and semi-thin sections were taken for electron microscopic and stereological analyses. Myelinated axon numbers, myelin sheath thicknesses, and axonal areas were estimated using stereological methods. RESULTS The groups had no significant differences regarding mean numbers of axons, mean axonal areas, or mean myelin sheath thicknesses (p > 0.05). Histological observations revealed impaired lamellae in the myelin sheath of most axons, and vacuolization was frequently observed between the myelin sheath and axon in the EMF-exposed group. The Mel and ω-3-treated EMF groups exhibited well-preserved myelinated nerve fibers and intact astrocytes and oligodendrocytes. CONCLUSIONS At the ultrastructural level, Mel and ω3 exhibits a neuroprotective effect on the optic nerve exposed to prenatal EMF. The protective effects of these antioxidants on oligodendrocytes, which play an essential role in myelin formation in the central nervous system, now require detailed investigation.
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Affiliation(s)
- Kıymet Kübra Tüfekci
- Department of Histology and Embryology, Faculty of Medicine, Kastamonu University, Kastamonu, Turkey
| | - Arife Ahsen Kaplan
- Department of Histology and Embryology, Faculty of Medicine, İstanbul Medipol University, İstanbul, Turkey
| | - Ayşenur Kaya
- Department of Histology and Embryology, Faculty of Medicine, Karamanoğlu Mehmetbey University, Karaman, Turkey
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Aziza Alrafiah
- Medical Laboratory Sciences Department, Faculty of Applied Medical Sciences, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Gamze Altun
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Abit Aktaş
- Department of Histology and Embryology, Faculty of Veterinary Medicine, İstanbul Cerrahpaşa University, İstanbul, Turkey
| | - Süleyman Kaplan
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
- Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
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12
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Liu T, Liu Y, Peng M, Liu Q, Si G. Slain2 attenuates brain injury following subarachnoid hemorrhage by controlling axonal microtubule structure in mice. Neurosci Lett 2023; 816:137495. [PMID: 37741612 DOI: 10.1016/j.neulet.2023.137495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 09/09/2023] [Accepted: 09/11/2023] [Indexed: 09/25/2023]
Abstract
Neuronal injury is accountable for the poor outcome of SAH patients. In this study, oxyhemoglobin (oxyHb) was used to treat cultured primary neurons to simulate SAH, while the SAH model was established by vascular puncture in mice. First, proteomics analysis and western blot assays showed Slain2 as an increased factor in neurons exposed to oxyHb treatment, which has been reported to play an important role in axonal development by regulating microtubule stability. Upregulation of neuronal Slain2 was also detected in the murine SAH model compared with sham surgery. In addition, there was no sex difference in the protein level of Slain2 in either the sham-operated or SAH groups. Furthermore, Slain2 overexpression rescued SAH-induced sensorimotor impairments in mice, while Slain2 knockdown had the opposite effect. Finally, Slain2 overexpression rescued SAH-induced axonal injury both in vivo and in vitro, which was exacerbated by Slain2 knockdown. Thus, we demonstrate here that Slain2 acts as an endogenous protective factor of neuronal axonal microtubule structure, which plays a key role in the protection against SAH-induced neuronal axonal injury. Facilitated axonal microtubule structure by Slain2 overexpression may reduce SAH-induced axonal injury and neurobehavioral dysfunction.
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Affiliation(s)
- Ting Liu
- Department of Traditional Chinese Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324 Jingwu Road, Huaiyin District, Jinan City, Shandong Province, China; Shandong University of Traditional Chinese Medicine, China
| | - Yuan Liu
- Department of Traditional Chinese Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324 Jingwu Road, Huaiyin District, Jinan City, Shandong Province, China
| | - Min Peng
- Department of Traditional Chinese Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324 Jingwu Road, Huaiyin District, Jinan City, Shandong Province, China
| | - Qianqian Liu
- Department of Traditional Chinese Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324 Jingwu Road, Huaiyin District, Jinan City, Shandong Province, China
| | - Guomin Si
- Department of Traditional Chinese Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324 Jingwu Road, Huaiyin District, Jinan City, Shandong Province, China.
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13
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Schneeweis A, Pak DTS. Wherefore Art Tau? Functional importance of site-specific tau phosphorylation in diverse subcellular domains. Int J Biochem Cell Biol 2023; 164:106475. [PMID: 37778693 DOI: 10.1016/j.biocel.2023.106475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 09/26/2023] [Accepted: 09/26/2023] [Indexed: 10/03/2023]
Abstract
Tau has canonically been considered as an axonal protein, but studies have observed tau localization in other subcellular domains of neurons. This relocated tau has been identified in both physiological and pathological conditions, and it is often labeled mislocalized. Furthermore, these forms of tau are referred to as "hyperphosphorylated" without specifying the phosphosites involved. On the contrary, we speculate that tau may have multiple physiological functions in various locations regulated via specific phosphorylation sites, although this picture is obscured by a lack of comprehensive phosphosite analysis. Here, we examine findings in the literature on the subcellular location of tau and potential roles tau has in those regions. We intentionally focus on the site-specific phosphorylated patterns involved in governing these properties, which are not well elucidated. To facilitate understanding of these events, we have begun establishing a comprehensive map of tau phosphorylation signatures. Such efforts may clarify tau's diverse physiological functions beyond the axon as well as promote development of novel therapeutic strategies directed against distinct tau subpopulations.
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Affiliation(s)
- Amanda Schneeweis
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Daniel T S Pak
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20057, USA.
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14
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Pizzano S, Sterne GR, Veling MW, Xu LA, Hergenreder T, Ye B. The Drosophila homolog of APP promotes Dscam expression to drive axon terminal growth, revealing interaction between Down syndrome genes. Dis Model Mech 2023; 16:dmm049725. [PMID: 37712356 PMCID: PMC10508694 DOI: 10.1242/dmm.049725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 08/08/2023] [Indexed: 09/16/2023] Open
Abstract
Down syndrome (DS) is caused by triplication of human chromosome 21 (HSA21). Although several HSA21 genes have been found to be responsible for aspects of DS, whether and how HSA21 genes interact with each other is poorly understood. DS patients and animal models present with a number of neurological changes, including aberrant connectivity and neuronal morphology. Previous studies have indicated that amyloid precursor protein (APP) and Down syndrome cell adhesion molecule (DSCAM) regulate neuronal morphology and contribute to neuronal aberrations in DS. Here, we report the functional interaction between the Drosophila homologs of these two genes, Amyloid precursor protein-like (Appl) and Dscam (Dscam1). We show that Appl requires Dscam to promote axon terminal growth in sensory neurons. Moreover, Appl increases Dscam protein expression post-transcriptionally. We further demonstrate that regulation of Dscam by Appl does not require the Appl intracellular domain or second extracellular domain. This study presents an example of functional interactions between HSA21 genes, providing insights into the pathogenesis of neuronal aberrations in DS.
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Affiliation(s)
- Sarah Pizzano
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gabriella R. Sterne
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Macy W. Veling
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - L. Amanda Xu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ty Hergenreder
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Bing Ye
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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15
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Ionescu A, Altman T, Perlson E. Looking for answers far away from the soma-the (un)known axonal functions of TDP-43, and their contribution to early NMJ disruption in ALS. Mol Neurodegener 2023; 18:35. [PMID: 37259156 DOI: 10.1186/s13024-023-00623-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 05/01/2023] [Indexed: 06/02/2023] Open
Abstract
Axon degeneration and Neuromuscular Junction (NMJ) disruption are key pathologies in the fatal neurodegenerative disease Amyotrophic Lateral Sclerosis (ALS). Despite accumulating evidence that axons and NMJs are impacted at a very early stage of the disease, current knowledge about the mechanisms leading to their degeneration remains elusive. Cytoplasmic mislocalization and accumulation of the protein TDP-43 are considered key pathological hallmarks of ALS, as they occur in ~ 97% of ALS patients, both sporadic and familial. Recent studies have identified pathological accumulation of TDP-43 in intramuscular nerves of muscle biopsies collected from pre-diagnosed, early symptomatic ALS patients. These findings suggest a gain of function for TDP-43 in axons, which might facilitate early NMJ disruption. In this review, we dissect the process leading to axonal TDP-43 accumulation and phosphorylation, discuss the known and hypothesized roles TDP-43 plays in healthy axons, and review possible mechanisms that connect TDP-43 pathology to the axon and NMJ degeneration in ALS.
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Affiliation(s)
- Ariel Ionescu
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Room 605, Ramat Aviv, 69978, Tel Aviv, Israel
| | - Topaz Altman
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Room 605, Ramat Aviv, 69978, Tel Aviv, Israel
| | - Eran Perlson
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Room 605, Ramat Aviv, 69978, Tel Aviv, Israel.
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
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16
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Huang LY, Sun X, Pan HX, Wang L, He CQ, Wei Q. Cell transplantation therapies for spinal cord injury focusing on bone marrow mesenchymal stem cells: Advances and challenges. World J Stem Cells 2023; 15:385-399. [PMID: 37342219 PMCID: PMC10277963 DOI: 10.4252/wjsc.v15.i5.385] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/17/2023] [Accepted: 03/21/2023] [Indexed: 05/26/2023] Open
Abstract
Spinal cord injury (SCI) is a devastating condition with complex pathological mechanisms that lead to sensory, motor, and autonomic dysfunction below the site of injury. To date, no effective therapy is available for the treatment of SCI. Recently, bone marrow-derived mesenchymal stem cells (BMMSCs) have been considered to be the most promising source for cellular therapies following SCI. The objective of the present review is to summarize the most recent insights into the cellular and molecular mechanism using BMMSC therapy to treat SCI. In this work, we review the specific mechanism of BMMSCs in SCI repair mainly from the following aspects: Neuroprotection, axon sprouting and/or regeneration, myelin regeneration, inhibitory microenvironments, glial scar formation, immunomodulation, and angiogenesis. Additionally, we summarize the latest evidence on the application of BMMSCs in clinical trials and further discuss the challenges and future directions for stem cell therapy in SCI models.
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Affiliation(s)
- Li-Yi Huang
- Rehabilitation Medicine Center and Institute of Rehabilitation Medicine, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610044, Sichuan Province, China
| | - Xin Sun
- Rehabilitation Medicine Center and Institute of Rehabilitation Medicine, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610044, Sichuan Province, China
| | - Hong-Xia Pan
- Rehabilitation Medicine Center and Institute of Rehabilitation Medicine, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610044, Sichuan Province, China
| | - Lu Wang
- Rehabilitation Medicine Center and Institute of Rehabilitation Medicine, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610044, Sichuan Province, China
| | - Cheng-Qi He
- Rehabilitation Medicine Center and Institute of Rehabilitation Medicine, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610044, Sichuan Province, China
| | - Quan Wei
- Rehabilitation Medicine Center and Institute of Rehabilitation Medicine, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610044, Sichuan Province, China
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17
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Wang LM, Kuhl E. Mechanics of axon growth and damage: A systematic review of computational models. Semin Cell Dev Biol 2023; 140:13-21. [PMID: 35474150 DOI: 10.1016/j.semcdb.2022.04.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 04/12/2022] [Accepted: 04/19/2022] [Indexed: 01/28/2023]
Abstract
Normal axon development depends on the action of mechanical forces both generated within the cytoskeleton and outside the cell, but forces of large magnitude or rate cause damage instead. Computational models aid scientists in studying the role of mechanical forces in axon growth and damage. These studies use simulations to evaluate how different sources of force generation within the cytoskeleton interact with each other to regulate axon elongation and retraction. Furthermore, mathematical models can help optimize externally applied tension to promote axon growth without causing damage. Finally, scientists also use simulations of axon damage to investigate how forces are distributed among different components of the axon and how the tissue surrounding an axon influences its susceptibility to injury. In this review, we discuss how computational studies complement experimental studies in the areas of axon growth, regeneration, and damage.
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Affiliation(s)
- Lucy M Wang
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
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18
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Zou Y, Guo Q, Chang Y, Zhong Y, Cheng L, Wei W. Alternative splicing affects synapses in the hippocampus of offspring after maternal fructose exposure during gestation and lactation. Chem Biol Interact 2023; 379:110518. [PMID: 37121297 DOI: 10.1016/j.cbi.2023.110518] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/15/2023] [Accepted: 04/27/2023] [Indexed: 05/02/2023]
Abstract
Increased fructose over-intake is a global issue. Maternal fructose exposure during gestation and lactation can impair brain development in offspring. However, the effect on synapses is still unknown. For the diversification of RNA and biological functions, alternative splicing (AS) and alternative polyadenylation (APA) are essential. We constructed a maternal high-fructose diet model by administering 13% and 40% fructose water. The student's t-test analyzed the results of RT-qPCR. All other results were analyzed by one-way analysis of variance. The animal behavior experiment results revealed that conditioning and associative memory had been damaged. The proteins that form synapses were consistently low-expressed. In addition, compared with the control group, the Oxford Nanopore Technologies platform's full-length RNA-sequencing identified 298 different spliced genes (DSGs) and 51 differentially expressed alternative splicing (DEAS) genes in the 13% fructose group. 313 DSGs and 74 DEAS genes were in the 40% fructose group. Enrichment analysis based on these altered genes revealed some enlightening items and pathways. Our findings demonstrated the transcriptome mechanism underlying maternal fructose exposure during gestation and lactation and impaired synapse function during the transcripts' editing.
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Affiliation(s)
- Yuchen Zou
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Qing Guo
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Yidan Chang
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Yongyong Zhong
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Lin Cheng
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Wei Wei
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China.
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19
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Zhong Y, Wang J, Beckel J, de Groat WC, Tai C. Mechanisms Underlying Poststimulation Block Induced by High-Frequency Biphasic Stimulation. Neuromodulation 2023; 26:577-588. [PMID: 34278654 PMCID: PMC8766610 DOI: 10.1111/ner.13501] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/30/2021] [Accepted: 06/21/2021] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To reveal the possible mechanisms underlying poststimulation block induced by high-frequency biphasic stimulation (HFBS). MATERIALS AND METHODS A new axonal conduction model is developed for unmyelinated axons. This new model is different from the classical axonal conduction model by including both ion concentrations and membrane ion pumps to allow analysis of axonal responses to long-duration stimulation. Using the new model, the post-HFBS block phenomenon reported in animal studies is simulated and analyzed for a wide range of stimulation frequencies (100 Hz-10 kHz). RESULTS HFBS can significantly change the Na+ and K+ concentrations inside and outside the axon to produce a post-HFBS block of either short-duration (<500 msec) or long-duration (>3 sec) depending on the duration of HFBS. The short-duration block is due to the fast recovery of the Na+ and K+ concentrations outside the axon in periaxonal space by diffusion of ions into and from the large extracellular space, while the long-duration block is due to the slow restoration of the normal Na+ concentration inside the axon by membrane ion pumps. The 100 Hz HFBS requires the minimal electrical energy to achieve the post-HFBS block, while the 10 kHz stimulation is the least effective frequency requiring high intensity and long duration to achieve the block. CONCLUSION This study reveals two possible ionic mechanisms underlying post-HFBS block of axonal conduction. Understanding these mechanisms is important for improving clinical applications of HFBS block and for developing new nerve block methods employing HFBS.
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Affiliation(s)
- Yihua Zhong
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA; School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Jicheng Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jonathan Beckel
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Changfeng Tai
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
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20
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Song Z, Mao H, Liu J, Sun W, Wu S, Lu X, Jin C, Yang J. Lanthanum Chloride Induces Axon Abnormality Through LKB1-MARK2 and LKB1-STK25-GM130 Signaling Pathways. Cell Mol Neurobiol 2023; 43:1181-1196. [PMID: 35661286 DOI: 10.1007/s10571-022-01237-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/23/2022] [Indexed: 11/24/2022]
Abstract
Lanthanum (La) is a natural rare-earth element that can damage the central nervous system and impair learning and memory. However, its neurotoxic mechanism remains unclear. In this study, adult female rats were divided into 4 groups and given distilled water solution containing 0%, 0.125%, 0.25%, and 0.5% LaCl3, respectively, and this was done from conception to the end of the location. Their offspring rats were used to establish animal models to investigate LaCl3 neurotoxicity. Primary neurons cultured in vitro were treated with LaCl3 and infected with LKB1 overexpression lentivirus. The results showed that LaCl3 exposure resulted in abnormal axons in the hippocampus and primary cultured neurons. LaCl3 reduced the expression of LKB1, p-LKB1, STRAD and MO25 proteins, and directly or indirectly affected the expression of LKB1, leading to decreased activity of LKB1-MARK2 and LKB1-STK25-GM130 pathways. This study indicated that LaCl3 exposure could interfere with the normal effects of LKB1 in the brain and downregulate LKB1-MARK2 and LKB1-STK25-GM130 signaling pathways, resulting in abnormal axon in offspring rats.
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Affiliation(s)
- Zeli Song
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Haoyue Mao
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Jinxuan Liu
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Wenchang Sun
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Shengwen Wu
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Xiaobo Lu
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Cuihong Jin
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China
| | - Jinghua Yang
- Department of Toxicology, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang, 110122, People's Republic of China.
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21
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Kikuchi S, Kohno T, Kojima T, Tatsumi H, Ohsaki Y, Ninomiya T. Oxygen-Glucose Deprivation Decreases the Motility and Length of Axonal Mitochondria in Cultured Dorsal Root Ganglion Cells of Rats. Cell Mol Neurobiol 2023; 43:1267-80. [PMID: 35771293 DOI: 10.1007/s10571-022-01247-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/20/2022] [Indexed: 11/03/2022]
Abstract
Controlling axonal mitochondria is important for maintaining normal function of the neural network. Oxygen-glucose deprivation (OGD), a model used for mimicking ischemia, eventually induces neuronal cell death similar to axonal degeneration. Axonal mitochondria are disrupted during OGD-induced neural degeneration; however, the mechanism underlying mitochondrial dysfunction has not been completely understood. We focused on the dynamics of mitochondria in axons exposed to OGD; we observed that the number of motile mitochondria significantly reduced in 1 h following OGD exposure. In our observation, the decreased length of stationary mitochondria was affected by the following factors: first, the halt of motile mitochondria; second, the fission of longer stationary mitochondria; and third, a transformation from tubular to spherical shape in OGD-exposed axons. Motile mitochondria reduction preceded stationary mitochondria fragmentation in OGD exposure; these conditions induced the decrease of stationary mitochondria in three different ways. Our results suggest that mitochondrial morphological changes precede the axonal degeneration while ischemia-induced neurodegeneration.
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22
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Pestronk A, Schmidt RE, Bucelli R, Sim J. Schwann Cells and Myelin in Human Peripheral Nerve: Major Protein Components Vary with Age, Axon Size and Pathology. Neuropathol Appl Neurobiol 2023; 49:e12898. [PMID: 36868780 DOI: 10.1111/nan.12898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/28/2022] [Accepted: 02/21/2023] [Indexed: 03/05/2023]
Abstract
AIMS We examined major protein components of Schwann cells (SC) and myelin in normal and diseased human peripheral nerves. METHODS We evaluated distributions of neural cell adhesion molecule (NCAM), P0 protein (P0), and myelin basic protein (MBP) in frozen sections of 98 sural nerves. RESULTS Non-myelinating SC in normal adults, contained NCAM, but not P0 or MBP. With chronic axon loss, SC without associated axons (Büngner band cells) often co-stained for both NCAM and P0. Onion bulb cells also co-stained for both P0 and NCAM. Infants had many SC with MBP but no P0. All myelin sheaths contained P0. Myelin around large, and some intermediate-sized, axons co-stained for both MBP and P0. Myelin on other intermediate-sized axons had P0, but no MBP. Regenerated axons often had sheaths with MBP, P0, and some NCAM. During active axon degeneration, myelin ovoids often co-stained for MBP, P0 and NCAM. Demyelinating neuropathy patterns included SC (NCAM) loss, and myelin with abnormally distributed, or reduced, P0. CONCLUSIONS Peripheral nerve SC and myelin have varied molecular phenotypes, related to age, axon size and nerve pathology. In normal adult peripheral nerve, myelin has two different patterns of molecular composition. MBP is mostly absent from myelin around a population of intermediate-sized axons, while P0 is present in myelin around all axons. Denervated SC have a molecular signature that differs from normal SC types. With acute denervation, SC may stain for both NCAM and MBP. Chronically denervated SC often stain for both NCAM and P0.
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Affiliation(s)
- Alan Pestronk
- Departments of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA.,Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Robert E Schmidt
- Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Robert Bucelli
- Departments of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA.,Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Julia Sim
- Departments of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA
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Abstract
Degenerative ataxias and hereditary spastic paraplegias (HSPs) form a continuous, often overlapping disease spectrum sharing not only phenotypic features and underlying genes, but also cellular pathways and disease mechanisms. Mitochondrial metabolism presents a major molecular theme underlying both multiple ataxias and HSPs, thus indicating a heightened vulnerability of Purkinje cells, spinocerebellar tracts, and motor neurons to mitochondrial dysfunction, which is of particular interest for translational approaches. Mitochondrial dysfunction might be the primary (upstream) or secondary (downstream) result of a genetic defect, with underlying genetic defects in nuclear-encoded genes being much more frequent than in mtDNA genes in both, ataxias and HSPs. Here, we outline the substantial number of ataxias, spastic ataxias and HSPs caused by mutated genes implicated in (primary or secondary) mitochondrial dysfunction, highlighting several key "mitochondrial" ataxias and HSPs which are of particular interest for their frequency, pathogenesis and translational opportunities. We then showcase prototypic mitochondrial mechanisms by which disruption of these ataxia and HSP genes contributes to Purkinje cells or corticospinal neuron dysfunction, thus elucidating hypotheses on Purkinje cells and corticospinal neuron vulnerability to mitochondrial dysfunction.
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Affiliation(s)
- Matthis Synofzik
- Department of Neurodegenerative Diseases, Center for Neurology & Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany; German Center of Neurodegenerative Diseases (DZNE), Tübingen, Germany.
| | - Elena Rugarli
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, and Center for Molecular Medicine, University of Cologne, Cologne, Germany
| | - Evan Reid
- Cambridge Institute for Medical Research and Department of Medical Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Rebecca Schüle
- Department of Neurodegenerative Diseases, Center for Neurology & Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany; German Center of Neurodegenerative Diseases (DZNE), Tübingen, Germany
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Pizzolato M, Canales-Rodríguez EJ, Andersson M, Dyrby TB. Axial and radial axonal diffusivities and radii from single encoding strongly diffusion-weighted MRI. Med Image Anal 2023; 86:102767. [PMID: 36867913 DOI: 10.1016/j.media.2023.102767] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 12/13/2022] [Accepted: 02/08/2023] [Indexed: 02/18/2023]
Abstract
We enable the estimation of the per-axon axial diffusivity from single encoding, strongly diffusion-weighted, pulsed gradient spin echo data. Additionally, we improve the estimation of the per-axon radial diffusivity compared to estimates based on spherical averaging. The use of strong diffusion weightings in magnetic resonance imaging (MRI) allows to approximate the signal in white matter as the sum of the contributions from only axons. At the same time, spherical averaging leads to a major simplification of the modeling by removing the need to explicitly account for the unknown distribution of axonal orientations. However, the spherically averaged signal acquired at strong diffusion weightings is not sensitive to the axial diffusivity, which cannot therefore be estimated although needed for modeling axons - especially in the context of multi-compartmental modeling. We introduce a new general method for the estimation of both the axial and radial axonal diffusivities at strong diffusion weightings based on kernel zonal modeling. The method could lead to estimates that are free from partial volume bias with gray matter or other isotropic compartments. The method is tested on publicly available data from the MGH Adult Diffusion Human Connectome project. We report reference values of axonal diffusivities based on 34 subjects, and derive estimates of axonal radii from only two shells. The estimation problem is also addressed from the angle of the required data preprocessing, the presence of biases related to modeling assumptions, current limitations, and future possibilities.
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Affiliation(s)
- Marco Pizzolato
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark; Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark.
| | | | - Mariam Andersson
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
| | - Tim B Dyrby
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark; Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Copenhagen, Denmark
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25
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Imanaka C, Shimada S, Ito S, Kamada M, Iguchi T, Konishi Y. A model for generating differences in microtubules between axonal branches depending on the distance from terminals. Brain Res 2023; 1799:148166. [PMID: 36402177 DOI: 10.1016/j.brainres.2022.148166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/11/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022]
Abstract
In the remodeling of axonal arbor, the growth and retraction of branches are differentially regulated within a single axon. Although cell-autonomously generated differences in microtubule (MT) turnover are thought to be involved in selective branch regulation, the cellular system whereby neurons generate differences of MTs between axonal branches has not been clarified. Because MT turnover tends to be slower in longer branches compared with neighboring shorter branches, feedback regulation depending on branch length is thought to be involved. In the present study, we generated a model of MT lifetime in axonal terminal branches by adapting a length-dependent model in which parameters for MT dynamics were constant in the arbor. The model predicted that differences in MT lifetime between neighboring branches could be generated depending on the distance from terminals. In addition, the following points were predicted. Firstly, destabilization of MTs throughout the arbor decreased the differences in MT lifetime between branches. Secondly, differences of MT lifetime existed even before MTs entered the branch point. In axonal MTs in primary neurons, treatment with a low concentration of nocodazole significantly decreased the differences of detyrosination (deTyr) and tyrosination (Tyr) of tubulins, indicators of MT turnover. Expansion microscopy of the axonal shaft before the branch point revealed differences in deTyr/Tyr modification on MTs. Our model recapitulates the differences in MT turnover between branches and provides a feedback mechanism for MT regulation that depends on the axonal arbor geometry.
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Affiliation(s)
- Chiaki Imanaka
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Satoshi Shimada
- Department of Human and Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Shino Ito
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Marina Kamada
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Tokuichi Iguchi
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan; Department of Nursing, Faculty of Health Science, Fukui Health Science University, Fukui 910-3190, Japan
| | - Yoshiyuki Konishi
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan; Life Science Innovation Center, University of Fukui, Fukui 910-8507, Japan.
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26
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Cason SE, Fenton AR, Holzbaur ELF. Employing Live-Cell Imaging to Study Motor-Mediated Transport. Methods Mol Biol 2023; 2623:45-59. [PMID: 36602678 DOI: 10.1007/978-1-0716-2958-1_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Microtubule-based transport is a highly regulated process, requiring kinesin and/or dynein motors, a multitude of motor-associated regulatory proteins including activating adaptors and scaffolding proteins, and microtubule tracks that also provide regulatory cues. While in vitro studies are invaluable, fully replicating the physiological conditions under which motility occurs in cells is not yet possible. Here, we describe two methods that can be employed to study motor-based transport and motor regulation in a cellular context. Live-cell imaging of organelle transport in neurons leverages the uniform polarity of microtubules in axons to better understand the factors regulating microtubule-based motility. Peroxisome recruitment assays allow users to examine the net effect of motors and motor-regulatory proteins on organelle distribution. Together, these methods open the door to motility experiments that more fully interrogate the complex cellular environment.
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Affiliation(s)
- Sydney E Cason
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Adam R Fenton
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
- Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
- Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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27
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Jacobi A, Tran NM. Defining Selective Neuronal Resilience and Identifying Targets for Neuroprotection and Axon Regeneration Using Single-Cell RNA Sequencing: Experimental Approaches. Methods Mol Biol 2023; 2636:1-18. [PMID: 36881292 DOI: 10.1007/978-1-0716-3012-9_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
A prevalent feature among neurodegenerative conditions, including axonal injury, is that certain neuronal types are disproportionately affected, while others are more resilient. Identifying molecular features that separate resilient from susceptible populations could reveal potential targets for neuroprotection and axon regeneration. A powerful approach to resolve molecular differences across cell types is single-cell RNA-sequencing (scRNA-seq). scRNA-seq is a robustly scalable approach that enables the parallel sampling of gene expression across many individual cells. Here we present a systematic framework to apply scRNA-seq to track neuronal survival and gene expression changes following axonal injury. Our methods utilize the mouse retina because it is an experimentally accessible central nervous system tissue and its cell types have been comprehensively characterized by scRNA-seq. This chapter will focus on preparing retinal ganglion cells (RGCs) for scRNA-seq and pre-processing of sequencing results.
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Affiliation(s)
- Anne Jacobi
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Nicholas M Tran
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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28
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Kumar P, Sharma S, Kaur C, Pal I, Bhardwaj DN, Nag TC, Roy TS, Jacob TG. Nerve fibre morphometry with transmission electron microscopy: Application of the nucleator probe in ImageJ. MethodsX 2023; 10:102085. [PMID: 36926271 PMCID: PMC10011813 DOI: 10.1016/j.mex.2023.102085] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/18/2023] [Indexed: 03/05/2023] Open
Abstract
Stereology and semiautomated binary image histomorphometry are two common methods used for morphometry of nerve fibres. Nucleator probe can be used for the estimation of morphometric parameters like diameter, perimeter, area and volume of a structure that is approximately either a circle or a sphere. In this study, we estimated these parameters with the help of ImageJ software on calibrated transmission electron micrographs. We procured samples of the cochlear nerve (CN) during winter months, within 6-12 hours of death, to reduce post-mortem autolytic changes. The temporal bones containing the CN were fixed by immersion in chilled paraformaldehyde. After dissecting out from the petrous part of the temporal bone, the CN were osmicated and processed for embedding in resin. From the resin blocks, silver coloured (70 nm) ultrathin sections were cut and picked on 300-mesh copper grids, stained with uranyl acetate and lead citrate and viewed under Tecnai G2-20 transmission electron microscope. The transmission electron micrographs had scale bars embedded into them by the software at the time of imaging, and the morphometric parameters of randomly selected nerve fibres were measured using the ImageJ software. The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.•Nucleator probe is used for the estimation of morphometric parameters like diameter, perimeter, area or volume•Morphometric parameters were estimated by the ImageJ software on calibrated transmission electron micrographs•The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.
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Key Words
- Application of the nucleator probe with ImageJ
- Axon
- CN, cochlear nerve
- DDSA, Dodecenyl Succinic Anhydride
- DDW, double distilled water
- DMP-30, 2,4,6- Tri (dimethylaminomethyl) Phenol-30
- IAM, internal acoustic meatus: M, myelin
- MNA, Methyl Nadic Anhydride
- Myelin
- PB, phosphate buffer
- RT, room temperature
- Stereology
- axe, axon
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Affiliation(s)
- Punit Kumar
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Saroj Sharma
- Department of Anatomy, Dr. Baba Saheb Ambedkar Medical College & Hospital, Delhi, India
| | - Charanjeet Kaur
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Dept of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA, United States
| | - Indra Pal
- Department of Neurobiology School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Daya Nand Bhardwaj
- Department of Forensic Medicine & Toxicology, All India Institute of Medical Sciences, New Delhi, India
| | - Tapas Chandra Nag
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Tara Sankar Roy
- Department of Anatomy, North DMC Medical College & Hindu Rao Hospital, New Delhi, India
| | - Tony George Jacob
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
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Adula KP, Sagasti A. Live Imaging of Axonal Dynamics After Laser Axotomy of Peripheral Neurons in Zebrafish. Methods Mol Biol 2023; 2636:247-261. [PMID: 36881305 DOI: 10.1007/978-1-0716-3012-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Axon severing results in diverse outcomes, including successful regeneration and reestablishment of function, failure to regenerate, or neuronal cell death. Experimentally injuring an axon makes it possible to study degeneration of the distal stump that was detached from the cell body and document the successive steps of regeneration. Precise injury reduces damage to the environment surrounding an axon, and thereby the involvement of extrinsic processes, such as scarring or inflammation, enabling researchers to isolate the role that intrinsic factors play in regeneration. Several methods have been used to sever axons, each with advantages and disadvantages. This chapter describes using a laser on a two-photon microscope to cut individual axons of touch-sensing neurons in zebrafish larvae, and live confocal imaging to monitor its regeneration, a method that provides exceptional resolution.
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Affiliation(s)
- Kadidia P Adula
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA
| | - Alvaro Sagasti
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA.
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30
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Plotegher N. Physiological roles of organelles at the pre-synapse in neurons. Int J Biochem Cell Biol 2023; 154:106345. [PMID: 36521722 DOI: 10.1016/j.biocel.2022.106345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/03/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022]
Abstract
Mitochondria, endoplasmic reticulum and lysosomes are involved in different pathways that can regulate pre-synaptic function. In particular, they could modulate ATP availability in response to rapid changes, could control synaptic protein levels and adjust Ca2+ signalling, which could all impact on neuronal activity. Organelles functions in these processes need to be considered alone when describing the impact of pre-synaptic organelles on neurotransmission. However, the interplay among organelles, which occurs either via signalling pathways or through physical membranous contacts, has to be considered. In this brief review, the physiological role of organelles localized at the pre-synapse in neuronal function is discussed.
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31
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Madhoun S, Martins MTC, Korneva A, Johnson TV, Kimball E, Quillen S, Pease ME, Edwards M, Quigley H. Effects of experimental glaucoma in Lama1 nmf223 mutant mice. Exp Eye Res 2023; 226:109341. [PMID: 36476399 DOI: 10.1016/j.exer.2022.109341] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/10/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022]
Abstract
To identify changes in response to experimental intraocular pressure (IOP) elevation associated with the laminin α1 nmf223 mutation in mice. Laminin mutant (LM) mice (Lama1nmf223) and C57BL/6J (B6) mice in two age groups each (4-5 months and >1 year) underwent intracameral microbead injections to produce unilaterally elevated IOP. We assessed axonal transport block of immunofluorescently labeled amyloid precursor protein (APP) after 3 days and retinal ganglion cell (RGC) axon loss after 6 weeks. Light, electron and fluorescent microscopy was used to study baseline anatomic differences and effects of 3-day IOP elevation in younger LM mice. In younger mice of both LM and B6 strains, elevated IOP led to increased APP block in the retina, prelaminar optic nerve head (preONH), unmyelinated optic nerve (UON), and myelinated optic nerve (MON). APP blockade not significantly different between younger B6 and LM mouse strains. Older LM mice had greater APP accumulation in both control and glaucoma eyes compared to older B6, however, accumulation was not significantly greater in LM glaucoma eyes compared to LM controls. Axon loss at 6 weeks was 12.2% in younger LM and 18.7% in younger B6 mice (difference between strains, p = 0.22, Mann Whitney test). Untreated LM optic nerve area was lower compared to B6 (nerve area, p < 0.0001, t-test). Aberrant axon bundles, as well as defects, thickening and reduplication of pia mater, were seen in the optic nerves of younger LM mice. Axonal transport blockade significantly differed between old B6 and old LM mice in control and glaucoma eyes, and younger LM mice had abnormal axon paths and lower optic nerve area.
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Affiliation(s)
- Salaheddine Madhoun
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | | | - Arina Korneva
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Thomas V Johnson
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Elizabeth Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Sarah Quillen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Mary Ellen Pease
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Malia Edwards
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Harry Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
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32
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Moss HG, Benitez A, Jensen JH. Optimized rectification of fiber orientation density function with background threshold. Magn Reson Imaging 2023; 95:80-89. [PMID: 36368495 PMCID: PMC9695117 DOI: 10.1016/j.mri.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022]
Abstract
PURPOSE To describe an optimized fiber orientation density function (fODF) rectification procedure that removes negative values and absorbs all features below a specified threshold into a constant background. THEORY AND METHODS The fODF for a white matter imaging voxel describes the angular density of axons. Because of signal noise and Gibbs ringing, fODFs estimated with diffusion MRI may take on unphysical negative values in some directions and contain spurious peaks. In order to suppress such artifacts, an fODF rectification procedure is proposed that both eliminates all negative values and incorporates all features below a specified threshold, η, into a constant background while at the same time minimizing the mean square deviation from the original, unrectified fODF. Calculating this fODF is straightforward, and the directions and shapes of peaks not absorbed into the background are preserved. The rectification method is illustrated for an analytic fODF model and for experimental diffusion MRI data obtained in healthy human brain, with the original fODFs being obtained from fiber ball imaging. RESULTS Examples of optimal rectified fODFs are given for three choices of the background threshold referred to as minimal rectification (η = 0), average-level rectification (η ≈ 0.08), and fractional-anisotropy-axonal-based rectification (η ≈ 0.1). As η is increased, artifacts and other small features are more strongly suppressed, but the major fODF peaks are largely unaffected for the range of η values illustrated by these three alternatives. CONCLUSION Artifactual features of fODFs estimated with diffusion MRI can be effectively suppressed by applying the proposed optimized rectification procedure. Since it minimizes fODF distortion in the mean square sense, it may be useful in the study of how fODF fine structure is affected by aging and disease.
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Affiliation(s)
- Hunter G Moss
- Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States of America; Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States of America
| | - Andreana Benitez
- Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States of America; Department of Neurology, Medical University of South Carolina, Charleston, SC, United States of America
| | - Jens H Jensen
- Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States of America; Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States of America; Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, United States of America.
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33
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Eckel BD, Cruz R, Craig EM, Baas PW. Microtubule polarity flaws as a treatable driver of neurodegeneration. Brain Res Bull 2023; 192:208-215. [PMID: 36442694 DOI: 10.1016/j.brainresbull.2022.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/07/2022] [Accepted: 11/17/2022] [Indexed: 11/26/2022]
Abstract
Microtubule disruption is a common downstream mechanism leading to axonal degeneration in a number of neurological diseases. To date, most studies on this topic have focused on the loss of microtubule mass from the axon, as well as changes in the stability properties of the microtubules and/or their tubulin composition. Here we posit corruption of the normal pattern of microtubule polarity orientation as an underappreciated and yet treatable contributor to axonal degeneration. We include computational modeling to fortify the rigor of our considerations. Our simulations demonstrate that even a small deviation from the usual polarity pattern of axonal microtubules is detrimental to motor-based trafficking of organelles and other intracellular cargo. Additional modeling predicts that axons with such deviations will exhibit significantly reduced speed and reliability of organelle transport, and that localized clusters of wrongly oriented microtubules will result in traffic jams of accumulated organelles.
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Affiliation(s)
- Bridie D Eckel
- Dept Neurobiol/Anat, Drexel University, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | - Roy Cruz
- Dept Physics, Central Washington University, Ellensburg, WA 98926, USA
| | - Erin M Craig
- Dept Physics, Central Washington University, Ellensburg, WA 98926, USA
| | - Peter W Baas
- Dept Neurobiol/Anat, Drexel University, 2900 Queen Lane, Philadelphia, PA 19129, USA.
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34
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Abad-Rodríguez J, Brocca ME, Higuero AM. Glycans and Carbohydrate-Binding/Transforming Proteins in Axon Physiology. Adv Neurobiol 2023; 29:185-217. [PMID: 36255676 DOI: 10.1007/978-3-031-12390-0_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The mature nervous system relies on the polarized morphology of neurons for a directed flow of information. These highly polarized cells use their somatodendritic domain to receive and integrate input signals while the axon is responsible for the propagation and transmission of the output signal. However, the axon must perform different functions throughout development before being fully functional for the transmission of information in the form of electrical signals. During the development of the nervous system, axons perform environmental sensing functions, which allow them to navigate through other regions until a final target is reached. Some axons must also establish a regulated contact with other cells before reaching maturity, such as with myelinating glial cells in the case of myelinated axons. Mature axons must then acquire the structural and functional characteristics that allow them to perform their role as part of the information processing and transmitting unit that is the neuron. Finally, in the event of an injury to the nervous system, damaged axons must try to reacquire some of their immature characteristics in a regeneration attempt, which is mostly successful in the PNS but fails in the CNS. Throughout all these steps, glycans perform functions of the outermost importance. Glycans expressed by the axon, as well as by their surrounding environment and contacting cells, encode key information, which is fine-tuned by glycan modifying enzymes and decoded by glycan binding proteins so that the development, guidance, myelination, and electrical transmission functions can be reliably performed. In this chapter, we will provide illustrative examples of how glycans and their binding/transforming proteins code and decode instructive information necessary for fundamental processes in axon physiology.
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Affiliation(s)
- José Abad-Rodríguez
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain.
| | - María Elvira Brocca
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Alonso Miguel Higuero
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
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35
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Mitchell JW, Wildonger J. Live Imaging of Golgi Outposts in Drosophila Dendritic Arbors. Methods Mol Biol 2022; 2557:635-644. [PMID: 36512242 DOI: 10.1007/978-1-0716-2639-9_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Neurons are polarized cells whose polarity and morphology rely on the robust localization of cellular organelles and cargo to axons or dendrites. Developing neurons require an active secretory pathway, which includes the endoplasmic reticulum and Golgi apparatus, to supply membrane and proteins to growing dendrites and axons. In some neurons, a subset of the Golgi called Golgi "outposts" localize to dendrites and contribute to local secretory networks. The movement and positioning of Golgi outposts have been correlated with dendrite branch growth and stabilization as the dendritic arbor is established. Live imaging is essential to capture the dynamic nature of these organelles. Here we outline a protocol to image and quantify Golgi outposts in peripheral sensory neurons in live, intact Drosophila larvae.
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Affiliation(s)
- Josephine W Mitchell
- Integrated Program in Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.,Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Jill Wildonger
- Pediatrics, University of California, San Diego, La Jolla, CA, USA. .,Biological Sciences, Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA.
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36
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Hooshmand K, Goldstein D, Timmins HC, Li T, Harrison M, Friedlander ML, Lewis CR, Lees JG, Moalem-Taylor G, Guennewig B, Park SB, Kwok JB. Polygenic risk of paclitaxel-induced peripheral neuropathy: a genome-wide association study. J Transl Med 2022; 20:564. [PMID: 36474270 PMCID: PMC9724416 DOI: 10.1186/s12967-022-03754-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/04/2022] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Genetic risk factors for chemotherapy-induced peripheral neuropathy (CIPN), a major dose-limiting side-effect of paclitaxel, are not well understood. METHODS We performed a genome-wide association study (GWAS) in 183 paclitaxel-treated patients to identify genetic loci associated with CIPN assessed via comprehensive neuropathy phenotyping tools (patient-reported, clinical and neurological grading scales). Bioinformatic analyses including pathway enrichment and polygenic risk score analysis were used to identify mechanistic pathways of interest. RESULTS In total, 77% of the cohort were classified with CIPN (n = 139), with moderate/severe neuropathy in 36%. GWAS was undertaken separately for the three measures of CIPN. GWAS of patient-reported CIPN identified 4 chromosomal regions that exceeded genome-wide significance (rs9846958, chromosome 3; rs117158921, chromosome 18; rs4560447, chromosome 4; rs200091415, chromosome 10). rs4560447 is located within a protein-coding gene, LIMCH1, associated with actin and neural development and expressed in the dorsal root ganglia (DRG). There were additional risk loci that exceeded the statistical threshold for suggestive genome-wide association (P < 1 × 10-5) for all measures. A polygenic risk score calculated from the top 46 ranked SNPs was highly correlated with patient-reported CIPN (r2 = 0.53; P = 1.54 × 10-35). Overlap analysis was performed to identify 3338 genes which were in common between the patient-reported CIPN, neurological grading scale and clinical grading scale GWAS. The common gene set was subsequently analysed for enrichment of gene ontology (GO) and Reactome pathways, identifying a number of pathways, including the axon development pathway (GO:0061564; P = 1.78 × 10-6) and neuronal system (R-HSA-112316; adjusted P = 3.33 × 10-7). CONCLUSIONS Our findings highlight the potential role of axon development and regeneration pathways in paclitaxel-induced CIPN.
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Affiliation(s)
- Kosar Hooshmand
- grid.1013.30000 0004 1936 834XSchool of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XBrain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia
| | - David Goldstein
- grid.1005.40000 0004 4902 0432Prince of Wales Clinical School, University of New South Wales, Sydney, NSW Australia
| | - Hannah C. Timmins
- grid.1013.30000 0004 1936 834XSchool of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XBrain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia
| | - Tiffany Li
- grid.1013.30000 0004 1936 834XSchool of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XBrain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia
| | | | - Michael L. Friedlander
- grid.1005.40000 0004 4902 0432Prince of Wales Clinical School, University of New South Wales, Sydney, NSW Australia
| | - Craig R. Lewis
- grid.1005.40000 0004 4902 0432Prince of Wales Clinical School, University of New South Wales, Sydney, NSW Australia
| | - Justin G. Lees
- grid.1005.40000 0004 4902 0432School of Biomedical Sciences, University of New South Wales, UNSW Sydney, Sydney, NSW Australia
| | - Gila Moalem-Taylor
- grid.1005.40000 0004 4902 0432School of Biomedical Sciences, University of New South Wales, UNSW Sydney, Sydney, NSW Australia
| | - Boris Guennewig
- grid.1013.30000 0004 1936 834XSchool of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XBrain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia
| | - Susanna B. Park
- grid.1013.30000 0004 1936 834XSchool of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XBrain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia
| | - John B. Kwok
- grid.1013.30000 0004 1936 834XSchool of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XBrain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW Australia
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Swope RD, Hertzler JI, Stone MC, Kothe GO, Rolls MM. The exocyst complex is required for developmental and regenerative neurite growth in vivo. Dev Biol 2022; 492:1-13. [PMID: 36162553 PMCID: PMC10228574 DOI: 10.1016/j.ydbio.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/13/2022] [Accepted: 09/19/2022] [Indexed: 11/30/2022]
Abstract
The exocyst complex is an important regulator of intracellular trafficking and tethers secretory vesicles to the plasma membrane. Understanding of its role in neuron outgrowth remains incomplete, and previous studies have come to different conclusions about its importance for axon and dendrite growth, particularly in vivo. To investigate exocyst function in vivo we used Drosophila sensory neurons as a model system. To bypass early developmental requirements in other cell types, we used neuron-specific RNAi to target seven exocyst subunits. Initial neuronal development proceeded normally in these backgrounds, however, we considered this could be due to residual exocyst function. To probe neuronal growth capacity at later times after RNAi initiation, we used laser microsurgery to remove axons or dendrites and prompt regrowth. Exocyst subunit RNAi reduced axon regeneration, although new axons could be specified. In control neurons, a vesicle trafficking marker often concentrated in the new axon, but this pattern was disrupted in Sec6 RNAi neurons. Dendrite regeneration was also severely reduced by exocyst RNAi, even though the trafficking marker did not accumulate in a strongly polarized manner during normal dendrite regeneration. The requirement for the exocyst was not limited to injury contexts as exocyst subunit RNAi eliminated dendrite regrowth after developmental pruning. We conclude that the exocyst is required for injury-induced and developmental neurite outgrowth, but that residual protein function can easily mask this requirement.
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Affiliation(s)
- Rachel D Swope
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - J Ian Hertzler
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - Michelle C Stone
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - Gregory O Kothe
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, University Park, PA, 16802, USA.
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38
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Miryala CSJ, Holland ED, Dent EW. Contributions of microtubule dynamics and transport to presynaptic and postsynaptic functions. Mol Cell Neurosci 2022; 123:103787. [PMID: 36252720 PMCID: PMC9838116 DOI: 10.1016/j.mcn.2022.103787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/07/2022] [Accepted: 10/11/2022] [Indexed: 11/27/2022] Open
Abstract
Microtubules (MT) are elongated, tubular, cytoskeletal structures formed from polymerization of tubulin dimers. They undergo continuous cycles of polymerization and depolymerization, primarily at their plus ends, termed dynamic instability. Although this is an intrinsic property of MTs, there are a myriad of MT-associated proteins that function in regulating MT dynamic instability and other dynamic processes that shape the MT array. Additionally, MTs assemble into long, semi-rigid structures which act as substrates for long-range, motor-driven transport of many different types of cargoes throughout the cell. Both MT dynamics and motor-based transport play important roles in the function of every known type of cell. Within the last fifteen years many groups have shown that MT dynamics and transport play ever-increasing roles in the neuronal function of mature neurons. Not only are neurons highly polarized cells, but they also connect with one another through synapses to form complex networks. Here we will focus on exciting studies that have illuminated how MTs function both pre-synaptically in axonal boutons and post-synaptically in dendritic spines. It is becoming clear that MT dynamics and transport both serve important functions in synaptic plasticity. Thus, it is not surprising that disruption of MTs, either through hyperstabilization or destabilization, has profound consequences for learning and memory. Together, the studies described here suggest that MT dynamics and transport play key roles in synaptic function and when disrupted result in compromised learning and memory.
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Affiliation(s)
- Chandra S. J. Miryala
- Department of Neuroscience, University of Wisconsin, School of Medicine and Public Health, Madison, WI 53705
| | - Elizabeth D. Holland
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53705
| | - Erik W. Dent
- Department of Neuroscience, University of Wisconsin, School of Medicine and Public Health, Madison, WI 53705,Corresponding Author: Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705,
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Rossi SL, Subramanian P, Bu G, Di Polo A, Golde TE, Bovenkamp DE. Common features of neurodegenerative disease: exploring the brain-eye connection and beyond (part 2): the 2021 pre-symposium of the 15th international conference on Alzheimer's and Parkinson's diseases. Mol Neurodegener 2022; 17:69. [PMID: 36316783 PMCID: PMC9623952 DOI: 10.1186/s13024-022-00571-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 09/23/2022] [Indexed: 11/28/2022] Open
Affiliation(s)
- Sharyn L. Rossi
- grid.453152.40000 0000 8621 6363BrightFocus Foundation, 22512 Gateway Center Dr, Clarksburg, 20871 MD USA
| | - Preeti Subramanian
- grid.453152.40000 0000 8621 6363BrightFocus Foundation, 22512 Gateway Center Dr, Clarksburg, 20871 MD USA
| | - Guojun Bu
- grid.417467.70000 0004 0443 9942Department of Neuroscience, Mayo Clinic, Jacksonville, FL USA
| | - Adriana Di Polo
- grid.14848.310000 0001 2292 3357Departments of Neuroscience and Ophthalmology, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), University of Montreal, Montreal, QC Canada
| | - Todd E. Golde
- grid.15276.370000 0004 1936 8091Departments of Neuroscience and Neurology, Norman Fixel Institute for Neurological Diseases, Center for Translational Research in Neurodegenerative Disease, Evelyn F. and William L. McKnight Brain Institute, University of Florida, Gainesville, Fl USA ,grid.189967.80000 0001 0941 6502Departments of Pharmacology & Chemical Biology, and Neurology, Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, GA USA
| | - Diane E. Bovenkamp
- grid.453152.40000 0000 8621 6363BrightFocus Foundation, 22512 Gateway Center Dr, Clarksburg, 20871 MD USA
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40
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Song H, Chen C, Kelley B, Tomasevich A, Lee H, Dolle JP, Cheng J, Garcia B, Meaney DF, Smith DH. Traumatic brain injury recapitulates developmental changes of axons. Prog Neurobiol 2022; 217:102332. [PMID: 35870679 PMCID: PMC9454890 DOI: 10.1016/j.pneurobio.2022.102332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 11/28/2022]
Abstract
During development, half of brain white matter axons are maintained for growth, while the remainder undergo developmental axon degeneration. After traumatic brain injury (TBI), injured axons also appear to follow pathways leading to either degeneration or repair. These observations raise the intriguing, but unexamined possibility that TBI recapitulates developmental axonal programs. Here, we examined axonal changes in the developing brain in young rats and after TBI in adult rat. Multiple shared changes in axonal microtubule (MT) through tubulin post-translational modifications and MT associated proteins (MAPs), tau and MAP6, were found in both development and TBI. Specifically, degenerating axons in both development and TBI underwent phosphorylation of tau and excessive tubulin tyrosination, suggesting MT instability and depolyermization. Conversely, nearby axons without degenerating morphologies, had increased MAP6 expression and maintenance of tubulin acetylation, suggesting enhanced MT stabilization, thereby supporting survival or repair. Quantitative proteomics revealed similar signaling pathways of axon degeneration and growth/repair, including protein clusters and networks. This comparison approach demonstrates how focused evaluation of developmental processes may provide insight into pathways initiated by TBI. In particular, the data suggest that TBI may reawaken dormant axonal programs that direct axons towards either degeneration or growth/repair, supporting further study in this area.
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Affiliation(s)
- Hailong Song
- Department of Neurosurgery, Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Chen Chen
- Department of Computer Sciences, University of Missouri, Columbia, MO 65211, United States
| | - Brian Kelley
- Department of Neurosurgery, Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Alexandra Tomasevich
- Department of Neurosurgery, Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Hyoungjoo Lee
- Department of Biochemistry and Biophysics, Quantitative Proteomics Resource Core, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Jean-Pierre Dolle
- Department of Neurosurgery, Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Jianlin Cheng
- Department of Computer Sciences, University of Missouri, Columbia, MO 65211, United States
| | - Benjamin Garcia
- Department of Biochemistry and Biophysics, Quantitative Proteomics Resource Core, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - David F Meaney
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Douglas H Smith
- Department of Neurosurgery, Center for Brain Injury and Repair, University of Pennsylvania, Philadelphia, PA 19104, United States.
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41
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Kroll MW, Melinek J, Martin JA, Brave MA, Williams HE. Confusion between firearms and electrical weapons as a factor in police shootings. Forensic Sci Med Pathol 2022; 18:280-287. [PMID: 35067809 DOI: 10.1007/s12024-022-00457-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2022] [Indexed: 12/14/2022]
Abstract
Conducted electrical weapons (CEW) have risks including trauma associated with uncontrolled falls, probes penetrating the eye, and fume ignition. A lesser-known risk is weapon-confusion error with officers mistakenly discharging their firearm when they intended to deploy their electrical weapon. We searched for incidents of possible weapon confusion with the TASER® brand CEWs via open-source media, litigation filings, and a survey of CEW law enforcement master instructors. We found 19 incidents of possible CEW weapon confusion in law enforcement field uses from January 2001 to April 2021. We eliminated a case as not meeting our criteria for probable weapons confusion leaving 18 cases, thus giving a demonstrated CEW discharge risk of 3.9 per million with confidence limits (2.4-6.2 per million) by Wilson score interval. Ipsilateral carry of the weapons was historically correlated with increased risk vs. contralateral carry. Officer gender was not a predictor of weapon confusion. The psychological issues behind weapon confusion under stress are discussed. The concurrent carry of electrical weapons and firearms presents a very small but real risk of injury and death from confusion between an electrical weapon and a firearm.
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Affiliation(s)
- Mark W Kroll
- Biomedical Engineering, California Polytechnical Institute, San Luis Obispo, USA.
| | | | | | | | - Howard E Williams
- School of Criminal Justice and Criminology, Texas State University, San Marcos, TX, USA
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42
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Naznin F, Waise TMZ, Fernyhough P. Antagonism of the Muscarinic Acetylcholine Type 1 Receptor Enhances Mitochondrial Membrane Potential and Expression of Respiratory Chain Components via AMPK in Human Neuroblastoma SH-SY5Y Cells and Primary Neurons. Mol Neurobiol 2022. [PMID: 36002781 DOI: 10.1007/s12035-022-03003-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/16/2022] [Indexed: 12/05/2022]
Abstract
Impairments in mitochondrial physiology play a role in the progression of multiple neurodegenerative conditions, including peripheral neuropathy in diabetes. Blockade of muscarinic acetylcholine type 1 receptor (M1R) with specific/selective antagonists prevented mitochondrial dysfunction and reversed nerve degeneration in in vitro and in vivo models of peripheral neuropathy. Specifically, in type 1 and type 2 models of diabetes, inhibition of M1R using pirenzepine or muscarinic toxin 7 (MT7) induced AMP-activated protein kinase (AMPK) activity in dorsal root ganglia (DRG) and prevented sensory abnormalities and distal nerve fiber loss. The human neuroblastoma SH-SY5Y cell line has been extensively used as an in vitro model system to study mechanisms of neurodegeneration in DRG neurons and other neuronal sub-types. Here, we tested the hypothesis that pirenzepine or MT7 enhance AMPK activity and via this pathway augment mitochondrial function in SH-SY5Y cells. M1R expression was confirmed by utilizing a fluorescent dye, ATTO590-labeled MT7, that exhibits great specificity for this receptor. M1R antagonist treatment in SH-SY5Y culture increased AMPK phosphorylation and mitochondrial protein expression (OXPHOS). Mitochondrial membrane potential (MMP) was augmented in pirenzepine and MT7 treated cultured SH-SY5Y cells and DRG neurons. Compound C or AMPK-specific siRNA suppressed pirenzepine or MT7-induced elevation of OXPHOS expression and MMP. Moreover, muscarinic antagonists induced hyperpolarization by activating the M-current and, thus, suppressed neuronal excitability. These results reveal that negative regulation of this M1R-dependent pathway could represent a potential therapeutic target to elevate AMPK activity, enhance mitochondrial function, suppress neuropathic pain, and enhance nerve repair in peripheral neuropathy.
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43
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Henn RE, Noureldein MH, Elzinga SE, Kim B, Savelieff MG, Feldman EL. Glial-neuron crosstalk in health and disease: A focus on metabolism, obesity, and cognitive impairment. Neurobiol Dis 2022; 170:105766. [PMID: 35584728 PMCID: PMC10071699 DOI: 10.1016/j.nbd.2022.105766] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/28/2022] [Accepted: 05/11/2022] [Indexed: 12/12/2022] Open
Abstract
Dementia is a complex set of disorders affecting normal cognitive function. Recently, several clinical studies have shown that diabetes, obesity, and components of the metabolic syndrome (MetS) are associated with cognitive impairment, including dementias such as Alzheimer's disease. Maintaining normal cognitive function is an intricate process involving coordination of neuron function with multiple brain glia. Well-orchestrated bioenergetics is a central requirement of neurons, which need large amounts of energy but lack significant energy storage capacity. Thus, one of the most important glial functions is to provide metabolic support and ensure an adequate energy supply for neurons. Obesity and metabolic disease dysregulate glial function, leading to a failure to respond to neuron energy demands, which results in neuronal damage. In this review, we outline evidence for links between diabetes, obesity, and MetS components to cognitive impairment. Next, we focus on the metabolic crosstalk between the three major glial cell types, oligodendrocytes, astrocytes, and microglia, with neurons under physiological conditions. Finally, we outline how diabetes, obesity, and MetS components can disrupt glial function, and how this disruption might impair glia-neuron metabolic crosstalk and ultimately promote cognitive impairment.
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Affiliation(s)
- Rosemary E Henn
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America.
| | - Mohamed H Noureldein
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America.
| | - Sarah E Elzinga
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America.
| | - Bhumsoo Kim
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America.
| | - Masha G Savelieff
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America.
| | - Eva L Feldman
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America.
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Almasieh M, Faris H, Levin LA. Pivotal roles for membrane phospholipids in axonal degeneration. Int J Biochem Cell Biol 2022; 150:106264. [PMID: 35868612 DOI: 10.1016/j.biocel.2022.106264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/16/2022] [Accepted: 07/17/2022] [Indexed: 10/17/2022]
Abstract
Membrane phospholipids are critical components of several signaling pathways. Maintained in a variety of asymmetric distributions, their trafficking across the membrane can be induced by intra-, extra-, and intercellular events. A familiar example is the externalization of phosphatidylserine from the inner leaflet to the outer leaflet in apoptosis, inducing phagocytosis of the soma. Recently, it has been recognized that phospholipids in the axonal membrane may be a signal for axonal degeneration, regeneration, or other processes. This review focuses on key recent developments and areas for ongoing investigations. KEY FACTS: Phosphatidylserine externalization propagates along an axon after axonal injury and is delayed in the Wallerian degeneration slow (WldS) mutant. The ATP8A2 flippase mutant has spontaneous axonal degeneration. Microdomains of axonal degeneration in spheroid bodies have differential externalization of phosphatidylserine and phosphatidylethanolamine. Phospholipid trafficking could represent a mechanism for coordinated axonal degeneration and elimination, i.e. axoptosis, analogous to apoptosis of the cell body.
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Affiliation(s)
- Mohammadali Almasieh
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Canada
| | - Hannah Faris
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Canada
| | - Leonard A Levin
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, Canada.
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45
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Savelieff MG, Feldman EL, Stino AM. Neurological sequela and disruption of neuron-glia homeostasis in SARS-CoV-2 infection. Neurobiol Dis 2022; 168:105715. [PMID: 35364273 PMCID: PMC8963977 DOI: 10.1016/j.nbd.2022.105715] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/10/2022] [Accepted: 03/26/2022] [Indexed: 12/15/2022] Open
Abstract
The coronavirus disease 2019 (COVID-19) pandemic is responsible for 267 million infections and over 5 million deaths globally. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a single-stranded RNA beta-coronavirus, which causes a systemic inflammatory response, multi-organ damage, and respiratory failure requiring intubation in serious cases. SARS-CoV-2 can also trigger neurological conditions and syndromes, which can be long-lasting and potentially irreversible. Since COVID-19 infections continue to mount, the burden of SARS-CoV-2-induced neurologic sequalae will rise in parallel. Therefore, understanding the spectrum of neurological clinical presentations in SARS-CoV-2 is needed to manage COVID-19 patients, facilitate diagnosis, and expedite earlier treatment to improve outcomes. Furthermore, a deeper knowledge of the neurological SARS-CoV-2 pathomechanisms could uncover potential therapeutic targets to prevent or mitigate neurologic damage secondary to COVID-19 infection. Evidence indicates a multifaceted pathology involving viral neurotropism and direct neuroinvasion along with cytokine storm and neuroinflammation leading to nerve injury. Importantly, pathological processes in neural tissue are non-cell autonomous and occur through a concerted breakdown in neuron-glia homeostasis, spanning neuron axonal damage, astrogliosis, microgliosis, and impaired neuron-glia communication. A clearer mechanistic and molecular picture of neurological pathology in SARS-CoV-2 may lead to effective therapies that prevent or mitigate neural damage in patients contracting and developing severe COVID-19 infection.
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Affiliation(s)
- Masha G Savelieff
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America.
| | - Eva L Feldman
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America; Division of Neuromuscular Medicine, University of Michigan, Ann Arbor, MI, United States of America.
| | - Amro M Stino
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America; Division of Neuromuscular Medicine, University of Michigan, Ann Arbor, MI, United States of America.
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Thyagarajan P, Feng C, Lee D, Shorey M, Rolls MM. Microtubule polarity is instructive for many aspects of neuronal polarity. Dev Biol 2022; 486:56-70. [PMID: 35341730 PMCID: PMC9058238 DOI: 10.1016/j.ydbio.2022.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/04/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022]
Abstract
Many neurons in bilaterian animals are polarized with functionally distinct axons and dendrites. Microtubule polarity, microtubule stability, and the axon initial segment (AIS) have all been shown to influence polarized transport in neurons. Each of these cytoskeletal cues could act independently to control axon and dendrite identity, or there could be a hierarchy in which one acts upstream of the others. Here we test the hypothesis that microtubule polarity acts as a master regulator of neuronal polarity by using a Drosophila genetic background in which some dendrites have normal minus-end-out microtubule polarity and others have the axonal plus-end-out polarity. In these mosaic dendrite arbors, we found that ribosomes, which are more abundant in dendrites than axons, were reduced in plus-end-out dendrites, while an axonal cargo was increased. In addition, we determined that microtubule stability was different in plus-end-out and minus-end-out dendrites, with plus-end-out ones having more stable microtubules like axons. Similarly, we found that ectopic diffusion barriers, like those at the AIS, formed at the base of dendrites with plus-end-out regions. Thus, changes in microtubule polarity were sufficient to rearrange other cytoskeletal features associated with neuronal polarization. However, overall neuron shape was maintained with only subtle changes in branching in mosaic arbors. We conclude that microtubule polarity can act upstream of many aspects of intracellular neuronal polarization, but shape is relatively resilient to changes in microtubule polarity in vivo.
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Affiliation(s)
- Pankajam Thyagarajan
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chengye Feng
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - David Lee
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Matthew Shorey
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
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Li M, Lu S, Huang P, Xia T, Yu Z, Jiang W, Mao Y, Yang C, Yu S, Wu W, Zhang Y. High-quality, large-scale, semi-thin, & ultra-thin sections of the optic nerve in large animals: An optimized procedure. Exp Eye Res 2022; 219:108956. [PMID: 35367250 DOI: 10.1016/j.exer.2022.108956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/10/2022] [Accepted: 01/17/2022] [Indexed: 11/25/2022]
Abstract
Large animal model of optic nerve (ON) injury is an essential tool for translational medicine. Perfusion fixation with paraformaldehyde is mainly used for preparing the semi-thin (1-2 μm thick) and ultra-thin (<0.5 μm thick) sections of the ON tissues. However, this conventional fixation technique in large animals needs a large volume of fixatives, which increases the risk of toxic exposure and is environmentally unfriendly. Additionally, fixed residual ON cannot be used for other tests that require fresh tissue samples. Although conventional immersion fixation is feasible for preparing a semi-thin section of the ON in small animals (0.2-0.6 mm in diameter), it faces technical challenges when fixing the ON of large animals (3 mm in diameters), as increased diameter limits the permeability of the fixatives into deeper tissue. Therefore, we optimized the immersion-fixation method to obtain high-quality, large-scale, semi-thin, and ultra-thin sections for the ON of goat and rhesus macaques. Using this optimized technique, the ON microstructure was well preserved throughout the entire area of 1.5*1.5 square millimeters, allowing confident quantification of axon density/diameter on semi-thin section and identification of specific organelles and glial cells on ultra-thin sections. Furthermore, the optimized technique is a quick, simple, and environmentally friendly fixation method. Notably, the ON regions of large animals with or without an intact neurovascular system can be prepared for light and electron microscopy. In contrast, the residual unfixed ON from the same animal can be further utilized for experiments such as tissue culture and biomolecular tests.
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Affiliation(s)
- Mengyun Li
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Shenjian Lu
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - PingPing Huang
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Tian Xia
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Zhonghao Yu
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Wenhao Jiang
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Yiyang Mao
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Chen Yang
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China
| | - Shuaishuai Yu
- School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, 325027, China
| | - Wencan Wu
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China.
| | - Yikui Zhang
- The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, 325027, China.
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Choi S, Kang D, Kang J, Hong DK, Kang BS, Kho AR, Choi BY, Huh SO, Suh SW. The Role of Zinc in Axon Formation via the mTORC1 Pathway. Mol Neurobiol 2022; 59:3206-3217. [PMID: 35293604 DOI: 10.1007/s12035-022-02785-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 02/15/2022] [Indexed: 10/18/2022]
Abstract
Zinc is an essential micronutrient required for proper function during neuronal development because it can modulate neuronal function and structure. A fully functional description of zinc in axonal processing in the central nervous system remains elusive. Here, we define the role of intracellular zinc in axon formation and elongation, involving the mammalian target of rapamycin complex 1 (mTORC1). To investigate the involvement of zinc in axon growth, we performed an ex vivo culture of mouse hippocampal neurons and administrated ZnCl2 as a media supplement. At 2 days in vitro, the administration of zinc induced the formation of multiple and elongated axons in the ex vivo culture system. A similar outcome was witnessed in callosal projection neurons in a developing mouse brain. Treatment with extracellular zinc activated the mTORC1 signaling pathway in mouse hippocampal neuronal cultures. The zinc-dependent enhancement of neuronal processing was inhibited either by the deactivation of mTORC1 with RAPTOR shRNA or by mTOR-insensitive 4EBP1 mutants. Additionally, zinc-dependent mTORC1 activation enhanced the axonal translation of TC10 and Par3 may be responsible for axonal growth. We identified a promising role of zinc in controlling axonogenesis in the developing brain, which, in turn, may indicate a novel structural role of zinc in the cytoskeleton and developing neurons.
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Affiliation(s)
- Seunghyuk Choi
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Donghyeon Kang
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Jieun Kang
- Department of Pharmacology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Dae Ki Hong
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Beom Seok Kang
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - A Ra Kho
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Bo Young Choi
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Sung-Oh Huh
- Department of Pharmacology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea
| | - Sang Won Suh
- Department of Physiology, College of Medicine, Hallym University, Hallymdaehak-gil 1, Chuncheon, 24252, Republic of Korea.
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Abstract
The endocannabinoid (eCB) system is one of the most widespread neuromodulatory systems in the mammalian brain, with a multifaceted role in functions ranging from development to synaptic plasticity. Endocannabinoids are synthesized on demand from membrane lipid precursors, and act primarily on a single G-protein coupled receptor type, CB1, to carry out diverse functions. Despite the importance of the eCB system both in healthy brain function and in disease, critically important details of eCB signaling remained unknown. How eCBs are released from the membrane, how these lipid molecules are transported between cells, and how the distribution of their receptors is controlled, remained elusive. Recent advances in optical microscopy methods and biosensor engineering may open up new avenues for studying eCB signaling. We summarize applications of superresolution microscopy using single molecule localization to reveal distinct patterns of nanoscale CB1 distribution in neuronal axons and axon terminals. We review single particle tracking studies using quantum dots that allowed visualizing CB1 trajectories. We highlight the recent development of fluorescent eCB biosensors, that revealed spatiotemporally specific eCB release in live cells and live animals. Finally, we discuss future directions where method development may help to advance a precise understanding of eCB signaling.
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Affiliation(s)
- Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
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Kuznetsov IA, Kuznetsov AV. Can the lack of fibrillar form of alpha-synuclein in Lewy bodies be explained by its catalytic activity? Math Biosci 2022; 344:108754. [PMID: 34890628 PMCID: PMC8882444 DOI: 10.1016/j.mbs.2021.108754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 02/03/2023]
Abstract
Finding the causative pathophysiological mechanisms for Parkinson's disease (PD) is important for developing therapeutic interventions. Until recently, it was believed that Lewy bodies (LBs), the hallmark of PD, are mostly composed of alpha-synuclein (α-syn) fibrils. Recent results (Shahmoradian et al. (2019)) demonstrated that the fibrillar form of α-syn is lacking from LBs. Here we propose that this surprising observation can be explained by the catalytic activity of the fibrillar form of α-syn. We assumed that α-syn fibrils catalyze the formation of LBs, but do not become part of them. We developed a mathematical model based on this hypothesis. By using the developed model, we investigated the consequences of this hypothesis. In particular, the model suggests that the long incubation time of PD can be explained by a two-step aggregation process that leads to its development: (i) aggregation of monomeric α-syn into α-syn oligomers and fibrils and (ii) clustering of membrane-bound organelles, which may cause disruption of axonal trafficking and lead to neuron starvation and death. The model shows that decreasing the rate of destruction of α-syn aggregates in somatic lysosomes accelerates the formation of LBs. Another consequence of the model is the prediction that removing α-syn aggregates from the brain after the aggregation of membrane-bound organelles into LBs has started may not stop the progression of PD because LB formation is an autocatalytic process; hence, the formation of LBs will be catalyzed by aggregates of membrane-bound organelles even in the absence of α-syn aggregates. The performed sensitivity study made it possible to establish the hierarchy of model parameters with respect to their effect on the formation of vesicle aggregates in the soma.
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Affiliation(s)
- Ivan A. Kuznetsov
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA,Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrey V. Kuznetsov
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA
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