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Asghari Adib E, Shadrach JL, Reilly-Jankowiak L, Dwivedi MK, Rogers AE, Shahzad S, Passino R, Giger RJ, Pierchala BA, Collins CA. DLK signaling in axotomized neurons triggers complement activation and loss of upstream synapses. Cell Rep 2024; 43:113801. [PMID: 38363678 PMCID: PMC11088462 DOI: 10.1016/j.celrep.2024.113801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/27/2023] [Accepted: 01/31/2024] [Indexed: 02/18/2024] Open
Abstract
Axotomized spinal motoneurons (MNs) lose presynaptic inputs following peripheral nerve injury; however, the cellular mechanisms that lead to this form of synapse loss are currently unknown. Here, we delineate a critical role for neuronal kinase dual leucine zipper kinase (DLK)/MAP3K12, which becomes activated in axotomized neurons. Studies with conditional knockout mice indicate that DLK signaling activation in injured MNs triggers the induction of phagocytic microglia and synapse loss. Aspects of the DLK-regulated response include expression of C1q first from the axotomized MN and then later in surrounding microglia, which subsequently phagocytose presynaptic components of upstream synapses. Pharmacological ablation of microglia inhibits the loss of cholinergic C boutons from axotomized MNs. Together, the observations implicate a neuronal mechanism, governed by the DLK, in the induction of inflammation and the removal of synapses.
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Affiliation(s)
- Elham Asghari Adib
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Jennifer L Shadrach
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI, USA
| | | | - Manish K Dwivedi
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Abigail E Rogers
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Shameena Shahzad
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Ryan Passino
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Brian A Pierchala
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI, USA; Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Catherine A Collins
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA.
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2
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Grooms NW, Fitzgerald MQ, Zuckerman B, Ureña SE, Weinberger LS, Chung SH. Expression of thioredoxin-1 in the ASJ neuron corresponds with and enhances intrinsic regenerative capacity under lesion conditioning in C. elegans. FEBS Lett 2023; 597:1880-1893. [PMID: 37300530 PMCID: PMC10526644 DOI: 10.1002/1873-3468.14684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/02/2023] [Accepted: 05/17/2023] [Indexed: 06/12/2023]
Abstract
A conditioning lesion of the peripheral sensory axon triggers robust central axon regeneration in mammals. We trigger conditioned regeneration in the Caenorhabditis elegans ASJ neuron by laser surgery or genetic disruption of sensory pathways. Conditioning upregulates thioredoxin-1 (trx-1) expression, as indicated by trx-1 promoter-driven expression of green fluorescent protein and fluorescence in situ hybridization (FISH), suggesting trx-1 levels and associated fluorescence indicate regenerative capacity. The redox activity of trx-1 functionally enhances conditioned regeneration, but both redox-dependent and -independent activity inhibit non-conditioned regeneration. Six strains isolated in a forward genetic screen for reduced fluorescence, which suggests diminished regenerative potential, also show reduced axon outgrowth. We demonstrate an association between trx-1 expression and the conditioned state that we leverage to rapidly assess regenerative capacity.
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Affiliation(s)
- Noa W.F. Grooms
- Department of Bioengineering, Northeastern University, Boston, Massachusetts, 02115, USA
| | - Michael Q. Fitzgerald
- Department of Bioengineering, Northeastern University, Boston, Massachusetts, 02115, USA
| | - Binyamin Zuckerman
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA
| | - Samuel E. Ureña
- Department of Bioengineering, Northeastern University, Boston, Massachusetts, 02115, USA
| | - Leor S. Weinberger
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA
| | - Samuel H. Chung
- Department of Bioengineering, Northeastern University, Boston, Massachusetts, 02115, USA
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3
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Bu H, Li Z, Lu Y, Zhuang Z, Zhen Y, Zhang L. Deciphering the multifunctional role of dual leucine zipper kinase (DLK) and its therapeutic potential in disease. Eur J Med Chem 2023; 255:115404. [PMID: 37098296 DOI: 10.1016/j.ejmech.2023.115404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/19/2023] [Accepted: 04/19/2023] [Indexed: 04/27/2023]
Abstract
Dual leucine zipper kinase (DLK, MAP3K12), a serine/threonine protein kinase, plays a key role in neuronal development, as it regulates axon regeneration and degeneration through its downstream kinase. Importantly, DLK is closely related to the pathogenesis of numerous neurodegenerative diseases and the induction of β-cell apoptosis that leads to diabetes. In this review, we summarize the current understanding of DLK function, and then discuss the role of DLK signaling in human diseases. Furthermore, various types of small molecule inhibitors of DLK that have been published so far are described in detail in this paper, providing some strategies for the design of DLK small molecule inhibitors in the future.
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Affiliation(s)
- Haiqing Bu
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Zhijia Li
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Yingying Lu
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Zhiyao Zhuang
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Yongqi Zhen
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Lan Zhang
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China.
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4
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Shi Q, Yu J, Li PAA, Lu X, Wang W. MicroRNA-337 participates in the progression of early-stage diabetic retinopathy by upregulating MAP3K12. Minerva Med 2022; 113:1038-1040. [PMID: 33021359 DOI: 10.23736/s0026-4806.20.07035-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Qin Shi
- Department of Ophtalmology, Ningxia Medical University General Hospital, Yinchuan, China
| | - Jianqiang Yu
- Pharmaceutical Sciences, Ningxia Medical University, Yinchuan, China
| | - Ping-An Andy Li
- Pharmaceutical Sciences, American North Carolina Central University, Durham, NC, USA
| | - Xiaoli Lu
- Experimental Animal Center, Ningxia Medical University, Yinchuan, China
| | - Weiling Wang
- Department of Ophtalmology, Ningxia Medical University General Hospital, Yinchuan, China -
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5
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Kulkarni SS, Sabharwal V, Sheoran S, Basu A, Matsumoto K, Hisamoto N, Ghosh-Roy A, Koushika SP. UNC-16 alters DLK-1 localization and negatively regulates actin and microtubule dynamics in Caenorhabditis elegans regenerating neurons. Genetics 2021; 219:6359182. [PMID: 34740241 DOI: 10.1093/genetics/iyab139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
Neuronal regeneration after injury depends on the intrinsic growth potential of neurons. Our study shows that UNC-16, a Caenorhabditis elegans JIP3 homolog, inhibits axonal regeneration by regulating initiation and rate of regrowth. This occurs through the inhibition of the regeneration-promoting activity of the long isoform of DLK-1 and independently of the inhibitory short isoform of DLK-1. We show that UNC-16 promotes DLK-1 punctate localization in a concentration-dependent manner limiting the availability of the long isoform of DLK-1 at the cut site, minutes after injury. UNC-16 negatively regulates actin dynamics through DLK-1 and microtubule dynamics partially via DLK-1. We show that post-injury cytoskeletal dynamics in unc-16 mutants are also partially dependent on CEBP-1. The faster regeneration seen in unc-16 mutants does not lead to functional recovery. Our data suggest that the inhibitory control by UNC-16 and the short isoform of DLK-1 balances the intrinsic growth-promoting function of the long isoform of DLK-1 in vivo. We propose a model where UNC-16's inhibitory role in regeneration occurs through both a tight temporal and spatial control of DLK-1 and cytoskeletal dynamics.
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Affiliation(s)
- Sucheta S Kulkarni
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, 560065, India
| | - Vidur Sabharwal
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Seema Sheoran
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, 560065, India
| | - Atrayee Basu
- Department of Biotechnology National Brain Research Centre, Manesar 122052, India
| | - Kunihiro Matsumoto
- Department of Molecular Biology, Nagoya University, Nagoya 4648601, Japan
| | - Naoki Hisamoto
- Department of Molecular Biology, Nagoya University, Nagoya 4648601, Japan
| | - Anindya Ghosh-Roy
- Department of Biotechnology National Brain Research Centre, Manesar 122052, India
| | - Sandhya P Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
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6
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Wang C, Wan H, Li M, Zhang C. Celastrol attenuates ischemia/reperfusion-mediated memory dysfunction by downregulating AK005401/MAP3K12. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2021; 82:153441. [PMID: 33387968 DOI: 10.1016/j.phymed.2020.153441] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 11/11/2020] [Accepted: 12/15/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Oxidative stress induces mitochondrial dysfunction, causing memory loss. Long noncoding RNAs influence mitochondrial function and suppress oxidative stress by regulating target protein expression and gene transcription. Celastrol, a natural antioxidant extracted from Tripterygium wilfordii Hook F. ("Thunder of God Vine"), effectively alleviates oxidative stress-mediated tissue injury. In the present study, we examined the effects of celastrol on memory dysfunction induced by ischemia/reperfusion (I/R) and elucidated the mechanisms underlying these effects. METHODS C57BL/6 mice were used to mimic I/R using the bilateral common carotid clip reperfusion method, and a hippocampal cell line (HT-22) cells were used to establish a model of oxygen-glucose deprivation/reoxygenation (OGD/R). We observed changes in behavior and mitochondrial structure. Cell activity, cell respiration, and antioxidant capacity were measured. MAP3K12, p-JNK, p-c-Jun, p-Akt/Akt, PI3K, Bcl-2, and Bax expression were evaluated. RESULTS I/R or OGD/R significantly increased AK005401 and MAP3K12 expression, further attenuating PI3K/Akt activation, promoting reactive oxygen species generation and causing mitochondrial dysfunction and cell apoptosis, thereby resulting in memory dysfunction. Celastrol increased antioxidant capacity, inhibited cell apoptosis, and improved mitochondrial function, effectively improving learning and memory by downregulating AK005401 and MAP3K12 and activating PI3K/Akt. CONCLUSIONS The AK005401/MAP3K12 signaling pathway has an important role in I/R-mediated hippocampal injury, and celastrol can potentially reduce or possibly prevent I/R-induced neuronal injury by downregulating AK005401/MAP3K12 signaling.
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Affiliation(s)
- Chaoyun Wang
- Basic Medical School, Binzhou Medical University, Yantai, P. R. China.
| | - Hongzhi Wan
- School of Pharmacy, Binzhou Medical University, Yantai, P. R. China
| | - Miao Li
- School of Pharmacy, Binzhou Medical University, Yantai, P. R. China
| | - Chunxiang Zhang
- Department of Biomedical Engineering, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.
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7
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Jin Y, Zheng B. Multitasking: Dual Leucine Zipper-Bearing Kinases in Neuronal Development and Stress Management. Annu Rev Cell Dev Biol 2020; 35:501-521. [PMID: 31590586 DOI: 10.1146/annurev-cellbio-100617-062644] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The dual leucine zipper-bearing kinase (DLK) and leucine zipper-bearing kinase (LZK) are evolutionarily conserved MAPKKKs of the mixed-lineage kinase family. Acting upstream of stress-responsive JNK and p38 MAP kinases, DLK and LZK have emerged as central players in neuronal responses to a variety of acute and traumatic injuries. Recent studies also implicate their function in astrocytes, microglia, and other nonneuronal cells, reflecting their expanding roles in the multicellular response to injury and in disease. Of particular note is the potential link of these kinases to neurodegenerative diseases and cancer. It is thus critical to understand the physiological contexts under which these kinases are activated, as well as the signal transduction mechanisms that mediate specific functional outcomes. In this review we first provide a historical overview of the biochemical and functional dissection of these kinases. We then discuss recent findings on regulating their activity to enhance cellular protection following injury and in disease, focusing on but not limited to the nervous system.
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Affiliation(s)
- Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093, USA; .,Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA;
| | - Binhai Zheng
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA; .,VA San Diego Healthcare System, San Diego, California 92161, USA
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8
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Lizarraga-Valderrama LR, Nigmatullin R, Ladino B, Taylor CS, Boccaccini AR, Knowles JC, Claeyssens F, Haycock JW, Roy I. Modulation of neuronal cell affinity of composite scaffolds based on polyhydroxyalkanoates and bioactive glasses. ACTA ACUST UNITED AC 2020; 15:045024. [PMID: 32100724 DOI: 10.1088/1748-605x/ab797b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The biocompatibility and neuron regenerating properties of various bioactive glass (BG)/polyhydroxyalkanoate (PHA) blend composites were assessed in order to study their suitability for peripheral nerve tissue applications, specifically as lumen structures for nerve guidance conduits. BG/PHA blend composites were fabricated using Bioactive glass® 45 S5 (BG1) and BG 1393 (BG2) with the 25:75 poly(3-hydroxyoctanoate/poly3-hydroxybutyrate), 25:75 P(3HO)/P(3HB) blend (PHA blend). Various concentrations of each BG (0.5 wt%, 1.0 wt% and 2.5 wt%) were used to determine the effect of BG on neuronal growth and differentiation, in single culture using NG108-15 neuronal cells and in a co-culture along with RN22 Schwann cells. NG108-15 cells exhibited good growth and differentiation on all the PHA blend composites showing that both BGs have good biocompatibility at 0.5 wt%, 1.0 wt% and 2.5 wt% within the PHA blend. The Young's modulus values displayed by all the PHA blend/BG composites ranged from 385.6 MPa to 1792.6 MPa, which are able to provide the required support and protective effect for the regeneration of peripheral nerves. More specifically, the tensile strength obtained in the PHA blend/BG1 (1.0 wt%) (10.0 ± 0.6 MPa) was found to be similar to that of the rabbit peroneal nerve. This composite also exhibited the best biological performance in supporting growth and neuronal differentiation among all the substrates. The neurite extension on this composite was found to be remarkable with the neurites forming a complex connection network.
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Affiliation(s)
- Lorena R Lizarraga-Valderrama
- Applied Biotechnology Research Group, School of Life Sciences, College of Liberal Arts and Sciences, University of Westminster, London, United Kingdom. School of Life Sciences, Medical School, University of Nottingham, Nottigham, United Kingdom
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9
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Wang X, Zhou T, Maynard GD, Terse PS, Cafferty WB, Kocsis JD, Strittmatter SM. Nogo receptor decoy promotes recovery and corticospinal growth in non-human primate spinal cord injury. Brain 2020; 143:1697-1713. [PMID: 32375169 PMCID: PMC7850069 DOI: 10.1093/brain/awaa116] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 12/19/2019] [Accepted: 02/23/2020] [Indexed: 12/20/2022] Open
Abstract
After CNS trauma such as spinal cord injury, the ability of surviving neural elements to sprout axons, reorganize neural networks and support recovery of function is severely restricted, contributing to chronic neurological deficits. Among limitations on neural recovery are myelin-associated inhibitors functioning as ligands for neuronal Nogo receptor 1 (NgR1). A soluble decoy (NgR1-Fc, AXER-204) blocks these ligands and provides a means to promote recovery of function in multiple preclinical rodent models of spinal cord injury. However, the safety and efficacy of this reagent in non-human primate spinal cord injury and its toxicological profile have not been described. Here, we provide evidence that chronic intrathecal and intravenous administration of NgR1-Fc to cynomolgus monkey and to rat are without evident toxicity at doses of 20 mg and greater every other day (≥2.0 mg/kg/day), and far greater than the projected human dose. Adult female African green monkeys underwent right C5/6 lateral hemisection with evidence of persistent disuse of the right forelimb during feeding and right hindlimb during locomotion. At 1 month post-injury, the animals were randomized to treatment with vehicle (n = 6) or 0.10-0.17 mg/kg/day of NgR1-Fc (n = 8) delivered via intrathecal lumbar catheter and osmotic minipump for 4 months. One animal was removed from the study because of surgical complications of the catheter, but no treatment-related adverse events were noted in either group. Animal behaviour was evaluated at 6-7 months post-injury, i.e. 1-2 months after treatment cessation. The use of the impaired forelimb during spontaneous feeding and the impaired hindlimb during locomotion were both significantly greater in the treatment group. Tissue collected at 7-12 months post-injury showed no significant differences in lesion size, fibrotic scar, gliosis or neuroinflammation between groups. Serotoninergic raphespinal fibres below the lesion showed no deficit, with equal density on the lesioned and intact side below the level of the injury in both groups. Corticospinal axons traced from biotin-dextran-amine injections in the left motor cortex were equally labelled across groups and reduced caudal to the injury. The NgR1-Fc group tissue exhibited a significant 2-3-fold increased corticospinal axon density in the cervical cord below the level of the injury relative to the vehicle group. The data show that NgR1-Fc does not have preclinical toxicological issues in healthy animals or safety concerns in spinal cord injury animals. Thus, it presents as a potential therapeutic for spinal cord injury with evidence for behavioural improvement and growth of injured pathways in non-human primate spinal cord injury.
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Affiliation(s)
- Xingxing Wang
- Cellular Neuroscience, Neurodegeneration and Repair Program, Yale University School of Medicine, New Haven, CT, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Tianna Zhou
- Cellular Neuroscience, Neurodegeneration and Repair Program, Yale University School of Medicine, New Haven, CT, USA
| | | | - Pramod S Terse
- National Center for Translational Sciences, NIH, Rockville, MD, USA
| | - William B Cafferty
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Jeffery D Kocsis
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Stephen M Strittmatter
- Cellular Neuroscience, Neurodegeneration and Repair Program, Yale University School of Medicine, New Haven, CT, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
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10
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Ko SH, Apple EC, Liu Z, Chen L. Age-dependent autophagy induction after injury promotes axon regeneration by limiting NOTCH. Autophagy 2020; 16:2052-2068. [PMID: 31920157 DOI: 10.1080/15548627.2020.1713645] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Macroautophagy/autophagy is essential for maintaining cellular homeostasis through the degradation of organelles and proteins. It also has a prominent role in modulating aging. However, the role of autophagy in the neuronal response to axon injury and axon regeneration, particularly in the context of aging, remains largely unknown. Our candidate genetic screen for axon regeneration regulators has identified genes in the autophagy pathway. Using a reporter that monitors autophagosomes and autolysosomes, we were able to monitor the dynamics of autophagy during axon regeneration. In response to axon injury, there was a significant increase in the number of autophagic vesicles. Injury-triggered autophagy activation and axon regeneration capacity undergo an age-dependent decline, and autophagy-activating agents partially rescued these declines. We found that DLK-1 was both required and sufficient for injury-induced autophagy activation. Autophagic vesicles co-localized with the NOTCH4 ortholog, LIN-12 receptor, a previously identified inhibitor of axon regeneration. Epistasis analyses indicate that LIN-12 might be a target of autophagy in axon regeneration. Together, our data suggest that DLK-mediated injury signaling can activate autophagy, which might limit the level of LIN-12 and NOTCH proteins to promote axon regeneration. Our findings reveal that autophagy activation can promote axon regeneration in neurons that lack maximal regrowth capacity, providing a promising therapeutic strategy for axon injury. Abbreviations: 3-MA: 3-methyladenine; ALs: autolysosomes; APs: autophagosomes; ARF-6: ADP-Ribosylation Factor related 6; ATG-9: AuTophaGy (yeast Atg homolog) 9; ATG9A: autophagy related 9A; BA1: bafilomycin A1; BEC-1: BEClin (human autophagy) homolog; BECN1: beclin 1; C. elegans: Caenorhabditis elegans; CEBP-1: C/EBP (CCAAT/enhancer-binding protein) homolog; CNS: central nervous system; DLK-1: Dual-Leucine zipper Kinase; DMSO: dimethyl sulfoxide; DRG: dorsal root ganglion; FOS: Fos proto-oncogene, AP-1 transcription factor subunit; GABA: gamma-aminobutyric acid; GFP: green fluorescent protein; HDA-3: Histone DeAcetylase; IP3: inositol trisphosphate; ITR-1: Inositol Triphosphate Receptor; KLF-2: Kruppel-Like Factor (zinc finger protein) 2; LGG-1: LC3, GABARAP and GATE-16 family; MAK-2: MAP kinase Activated protein Kinase; MAP kinase: mitogen-activated protein kinase; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MKK-4: mitogen activated protein kinase kinase 4; MTOR: mechanistic target of rapamycin kinase; NGM: nematode growth medium; NICD: Notch intracellular domain; NOTCH: notch receptor; PLM: posterior lateral microtubule; PMK-3: P38 Map kinase family; PNS: peripheral nervous system; SCG10: superior cervical ganglion protein 10; SCI: spinal cord injury; UNC-51: UNCoordinated 51; ULK1: unc-51 like autophagy activating kinase 1; wnd: wallenda.
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Affiliation(s)
- Su-Hyuk Ko
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA.,Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA.,Department of Molecular Medicine, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA
| | - Ellen C Apple
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA.,Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA.,Department of Molecular Medicine, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA
| | - Zhijie Liu
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA
| | - Lizhen Chen
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA.,Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA.,Department of Molecular Medicine, University of Texas Health Science Center at San Antonio , San Antonio, TX, USA
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11
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Shin JE, Ha H, Kim YK, Cho Y, DiAntonio A. DLK regulates a distinctive transcriptional regeneration program after peripheral nerve injury. Neurobiol Dis 2019; 127:178-192. [PMID: 30735704 PMCID: PMC6588443 DOI: 10.1016/j.nbd.2019.02.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/03/2019] [Accepted: 02/04/2019] [Indexed: 12/13/2022] Open
Abstract
Following damage to a peripheral nerve, injury signaling pathways converge in the cell body to generate transcriptional changes that support axon regeneration. Here, we demonstrate that dual leucine zipper kinase (DLK), a central regulator of injury responses including axon regeneration and neuronal apoptosis, is required for the induction of the pro-regenerative transcriptional program in response to peripheral nerve injury. Using a sensory neuron-conditional DLK knockout mouse model, we show a time course for the dependency of gene expression changes on the DLK pathway after sciatic nerve injury. Gene ontology analysis reveals that DLK-dependent gene sets are enriched for specific functional annotations such as ion transport and immune response. A series of comparative analyses shows that the DLK-dependent transcriptional program is distinct from that promoted by the importin-dependent retrograde signaling pathway, while it is partially shared between PNS and CNS injury responses. We suggest that DLK-dependency might provide a selective filter for regeneration-associated genes among the injury-responsive transcriptome.
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Affiliation(s)
- Jung Eun Shin
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Hongseok Ha
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea; Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea
| | - Yoon Ki Kim
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea; Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea
| | - Yongcheol Cho
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea.
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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12
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Bremer J, Marsden KC, Miller A, Granato M. The ubiquitin ligase PHR promotes directional regrowth of spinal zebrafish axons. Commun Biol 2019; 2:195. [PMID: 31149640 PMCID: PMC6531543 DOI: 10.1038/s42003-019-0434-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/16/2019] [Indexed: 01/05/2023] Open
Abstract
To reconnect with their synaptic targets, severed axons need to regrow robustly and directionally along the pre-lesional trajectory. While mechanisms directing axonal regrowth are poorly understood, several proteins direct developmental axon outgrowth, including the ubiquitin ligase PHR (Mycbp2). Invertebrate PHR also limits regrowth of injured axons, whereas its role in vertebrate axonal regrowth remains elusive. Here we took advantage of the high regrowth capacity of spinal zebrafish axons and observed robust and directional regrowth following laser transection of spinal Mauthner axons. We found that PHR directs regrowing axons along the pre-lesional trajectory and across the transection site. At the transection site, initial regrowth of wild-type axons was multidirectional. Over time, misdirected sprouts were corrected in a PHR-dependent manner. Ablation of cyfip2, known to promote F-actin-polymerization and pharmacological inhibition of JNK reduced misdirected regrowth of PHR-deficient axons, suggesting that PHR controls directional Mauthner axonal regrowth through cyfip2- and JNK-dependent pathways.
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Affiliation(s)
- Juliane Bremer
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
| | - Kurt C. Marsden
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
- Present Address: Department of Biological Sciences, North Carolina State University, Raleigh, 27607 NC USA
| | - Adam Miller
- Institute of Neuroscience, University of Oregon, Eugene, 97405 OR USA
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
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13
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Dubový P, Klusáková I, Hradilová-Svíženská I, Brázda V, Kohoutková M, Joukal M. A Conditioning Sciatic Nerve Lesion Triggers a Pro-regenerative State in Primary Sensory Neurons Also of Dorsal Root Ganglia Non-associated With the Damaged Nerve. Front Cell Neurosci 2019; 13:11. [PMID: 30778286 PMCID: PMC6369159 DOI: 10.3389/fncel.2019.00011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/14/2019] [Indexed: 12/19/2022] Open
Abstract
The primary sensory neurons of dorsal root ganglia (DRG) are a very useful model to study the neuronal regenerative program that is a prerequisite for successful axon regeneration after peripheral nerve injury. Seven days after a unilateral sciatic nerve injury by compression or transection, we detected a bilateral increase in growth-associated protein-43 (GAP-43) and superior cervical ganglion-10 (SCG-10) mRNA and protein levels not only in DRG neurons of lumbar spinal cord segments (L4-L5) associated with injured nerve, but also in remote cervical segments (C6-C8). The increase in regeneration-associated proteins in the cervical DRG neurons was associated with the greater length of regenerated axons 1 day after ulnar nerve crush following prior sciatic nerve injury as compared to controls with only ulnar nerve crush. The increased axonal regeneration capacity of cervical DRG neurons after a prior conditioning sciatic nerve lesion was confirmed by neurite outgrowth assay of in vitro cultivated DRG neurons. Intrathecal injection of IL-6 or a JAK2 inhibitor (AG490) revealed a role for the IL-6 signaling pathway in activating the pro-regenerative state in remote DRG neurons. Our results suggest that the pro-regenerative state induced in the DRG neurons non-associated with the injured nerve reflects a systemic reaction of these neurons to unilateral sciatic nerve injury.
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Affiliation(s)
- Petr Dubový
- Department of Anatomy, Laboratory of Cellular and Molecular Neurobiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ilona Klusáková
- Department of Anatomy, Laboratory of Cellular and Molecular Neurobiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ivana Hradilová-Svíženská
- Department of Anatomy, Laboratory of Cellular and Molecular Neurobiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Václav Brázda
- Department of Anatomy, Laboratory of Cellular and Molecular Neurobiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Marcela Kohoutková
- Department of Anatomy, Laboratory of Cellular and Molecular Neurobiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Marek Joukal
- Department of Anatomy, Laboratory of Cellular and Molecular Neurobiology, Faculty of Medicine, Masaryk University, Brno, Czechia
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14
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Caneo M, Julian V, Byrne AB, Alkema MJ, Calixto A. Diapause induces functional axonal regeneration after necrotic insult in C. elegans. PLoS Genet 2019; 15:e1007863. [PMID: 30640919 PMCID: PMC6347329 DOI: 10.1371/journal.pgen.1007863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 01/25/2019] [Accepted: 11/29/2018] [Indexed: 02/07/2023] Open
Abstract
Many neurons are unable to regenerate after damage. The ability to regenerate after an insult depends on life stage, neuronal subtype, intrinsic and extrinsic factors. C. elegans is a powerful model to test the genetic and environmental factors that affect axonal regeneration after damage, since its axons can regenerate after neuronal insult. Here we demonstrate that diapause promotes the complete morphological regeneration of truncated touch receptor neuron (TRN) axons expressing a neurotoxic MEC-4(d) DEG/ENaC channel. Truncated axons of different lengths were repaired during diapause and we observed potent axonal regrowth from somas alone. Complete morphological regeneration depends on DLK-1 but neuronal sprouting and outgrowth is DLK-1 independent. We show that TRN regeneration is fully functional since animals regain their ability to respond to mechanical stimulation. Thus, diapause induced regeneration provides a simple model of complete axonal regeneration which will greatly facilitate the study of environmental and genetic factors affecting the rate at which neurons die.
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Affiliation(s)
- Mauricio Caneo
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago de Chile, Chile
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile
| | - Victoria Julian
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Alexandra B. Byrne
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Mark J. Alkema
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Andrea Calixto
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago de Chile, Chile
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile
- * E-mail: ,
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15
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Asghari Adib E, Smithson LJ, Collins CA. An axonal stress response pathway: degenerative and regenerative signaling by DLK. Curr Opin Neurobiol 2018; 53:110-119. [PMID: 30053694 DOI: 10.1016/j.conb.2018.07.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/02/2018] [Indexed: 02/08/2023]
Abstract
Signaling through the dual leucine zipper-bearing kinase (DLK) is required for injured neurons to initiate new axonal growth; however, activation of this kinase also leads to neuronal degeneration and death in multiple models of injury and neurodegenerative diseases. This has spurred current consideration of DLK as a candidate therapeutic target, and raises a vital question: in what context is DLK a friend or foe to neurons? Here, we review our current understanding of DLK's function and mechanisms in regulating both regenerative and degenerative responses to axonal damage and stress in the nervous system.
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Affiliation(s)
- Elham Asghari Adib
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Laura J Smithson
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Catherine A Collins
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
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16
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Girouard MP, Bueno M, Julian V, Drake S, Byrne AB, Fournier AE. The Molecular Interplay between Axon Degeneration and Regeneration. Dev Neurobiol 2018; 78:978-990. [PMID: 30022605 DOI: 10.1002/dneu.22627] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/29/2018] [Accepted: 06/04/2018] [Indexed: 12/30/2022]
Abstract
Neurons face a series of morphological and molecular changes following trauma and in the progression of neurodegenerative disease. In neurons capable of mounting a spontaneous regenerative response, including invertebrate neurons and mammalian neurons of the peripheral nervous system (PNS), axons regenerate from the proximal side of the injury and degenerate on the distal side. Studies of Wallerian degeneration slow (WldS /Ola) mice have revealed that a level of coordination between the processes of axon regeneration and degeneration occurs during successful repair. Here, we explore how shared cellular and molecular pathways that regulate both axon regeneration and degeneration coordinate the two distinct outcomes in the proximal and distal axon segments. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Marie-Pier Girouard
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
| | - Mardja Bueno
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
| | - Victoria Julian
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Sienna Drake
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
| | - Alexandra B Byrne
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Alyson E Fournier
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
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17
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The Heterochronic Gene lin-14 Controls Axonal Degeneration in C. elegans Neurons. Cell Rep 2018; 20:2955-2965. [PMID: 28930688 DOI: 10.1016/j.celrep.2017.08.083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 07/31/2017] [Accepted: 08/25/2017] [Indexed: 01/23/2023] Open
Abstract
The disproportionate length of an axon makes its structural and functional maintenance a major task for a neuron. The heterochronic gene lin-14 has previously been implicated in regulating the timing of key developmental events in the nematode C. elegans. Here, we report that LIN-14 is critical for maintaining neuronal integrity. Animals lacking lin-14 display axonal degeneration and guidance errors in both sensory and motor neurons. We demonstrate that LIN-14 functions both cell autonomously within the neuron and non-cell autonomously in the surrounding tissue, and we show that interaction between the axon and its surrounding tissue is essential for the preservation of axonal structure. Furthermore, we demonstrate that lin-14 expression is only required during a short period early in development in order to promote axonal maintenance throughout the animal's life. Our results identify a crucial role for LIN-14 in preventing axonal degeneration and in maintaining correct interaction between an axon and its surrounding tissue.
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18
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Distinct homeostatic modulations stabilize reduced postsynaptic receptivity in response to presynaptic DLK signaling. Nat Commun 2018; 9:1856. [PMID: 29748610 PMCID: PMC5945772 DOI: 10.1038/s41467-018-04270-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 04/16/2018] [Indexed: 11/08/2022] Open
Abstract
Synapses are constructed with the stability to last a lifetime, yet sufficiently flexible to adapt during injury. Although fundamental pathways that mediate intrinsic responses to neuronal injury have been defined, less is known about how synaptic partners adapt. We have investigated responses in the postsynaptic cell to presynaptic activation of the injury-related Dual Leucine Zipper Kinase pathway at the Drosophila neuromuscular junction. We find that the postsynaptic compartment reduces neurotransmitter receptor levels, thus depressing synaptic strength. Interestingly, this diminished state is stabilized through distinct modulations to two postsynaptic homeostatic signaling systems. First, a retrograde response normally triggered by reduced receptor levels is silenced, preventing a compensatory enhancement in presynaptic neurotransmitter release. However, when global presynaptic release is attenuated, a postsynaptic receptor scaling mechanism persists to adaptively stabilize this diminished neurotransmission state. Thus, the homeostatic set point of synaptic strength is recalibrated to a reduced state as synapses acclimate to injury.
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19
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Murillo B, Mendes Sousa M. Neuronal Intrinsic Regenerative Capacity: The Impact of Microtubule Organization and Axonal Transport. Dev Neurobiol 2018; 78:952-959. [PMID: 29738096 DOI: 10.1002/dneu.22602] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/20/2018] [Accepted: 04/25/2018] [Indexed: 11/06/2022]
Abstract
In the adult vertebrate central nervous system, axons generally fail to regenerate. In contrast, peripheral nervous system axons are able to form a growth cone and regenerate upon lesion. Among the multiple intrinsic mechanisms leading to the formation of a new growth cone and to successful axon regrowth, cytoskeleton organization and dynamics is central. Here we discuss how multiple pathways that define the regenerative capacity converge into the regulation of the axonal microtubule cytoskeleton and transport. We further explore the use of dorsal root ganglion neurons as a model to study the neuronal regenerative ability. Finally, we address some of the unanswered questions in the field, including the mechanisms by which axonal transport might be modulated by injury, and the relationship between microtubule organization, dynamics, and axonal transport. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Blanca Murillo
- Nerve Regeneration group, Instituto de Biologia Molecular e Celular - IBMC and Instituto de Inovação e Investigação em Saúde, University of Porto, Rua Alfredo Allen 208, Porto, 4200-135, Portugal
| | - Mónica Mendes Sousa
- Nerve Regeneration group, Instituto de Biologia Molecular e Celular - IBMC and Instituto de Inovação e Investigação em Saúde, University of Porto, Rua Alfredo Allen 208, Porto, 4200-135, Portugal
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20
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Chen L. Microtubules and axon regeneration in C. elegans. Mol Cell Neurosci 2018; 91:160-166. [PMID: 29551667 DOI: 10.1016/j.mcn.2018.03.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 11/28/2022] Open
Abstract
Axon regeneration is a fundamental and conserved process that allows the nervous system to repair circuits after trauma. Due to its conserved genome, transparent body, and relatively simple neuroanatomy, C. elegans has become a powerful model organism for studying the cellular and molecular mechanisms underlying axon regeneration. Various studies from different model organisms have found microtubule dynamics to be pivotal to axon regrowth. In this review, we will discuss the latest findings on how microtubule dynamics are regulated during axon regeneration in C. elegans. Understanding the mechanisms of axon regeneration will aid in the development of more effective therapeutic strategies for treatments of diseases involving disconnection of axons, such as spinal cord injury and stroke.
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Affiliation(s)
- Lizhen Chen
- Barshop Institute for Longevity and Aging Studies, Department of Cell Systems and Anatomy, Department of Molecular Medicine, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
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21
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Koch M, Nicolas M, Zschaetzsch M, de Geest N, Claeys A, Yan J, Morgan MJ, Erfurth ML, Holt M, Schmucker D, Hassan BA. A Fat-Facets-Dscam1-JNK Pathway Enhances Axonal Growth in Development and after Injury. Front Cell Neurosci 2018; 11:416. [PMID: 29472843 PMCID: PMC5809495 DOI: 10.3389/fncel.2017.00416] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 12/12/2017] [Indexed: 11/13/2022] Open
Abstract
Injury to the adult central nervous systems (CNS) can result in severe long-term disability because damaged CNS connections fail to regenerate after trauma. Identification of regulators that enhance the intrinsic growth capacity of severed axons is a first step to restore function. Here, we conducted a gain-of-function genetic screen in Drosophila to identify strong inducers of axonal growth after injury. We focus on a novel axis the Down Syndrome Cell Adhesion Molecule (Dscam1), the de-ubiquitinating enzyme Fat Facets (Faf)/Usp9x and the Jun N-Terminal Kinase (JNK) pathway transcription factor Kayak (Kay)/Fos. Genetic and biochemical analyses link these genes in a common signaling pathway whereby Faf stabilizes Dscam1 protein levels, by acting on the 3'-UTR of its mRNA, and Dscam1 acts upstream of the growth-promoting JNK signal. The mammalian homolog of Faf, Usp9x/FAM, shares both the regenerative and Dscam1 stabilizing activities, suggesting a conserved mechanism.
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Affiliation(s)
- Marta Koch
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Maya Nicolas
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Marlen Zschaetzsch
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Natalie de Geest
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Annelies Claeys
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Jiekun Yan
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Matthew J Morgan
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium
| | - Maria-Luise Erfurth
- Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium.,Neuronal Wiring Lab, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium
| | - Matthew Holt
- Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium.,Laboratory of Glia Biology, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium
| | - Dietmar Schmucker
- Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium.,Neuronal Wiring Lab, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium
| | - Bassem A Hassan
- Laboratory of Neurogenetics, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, KU Leuven, Leuven, Belgium.,Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut du Cerveau et de la Moelle Epinière, Hôpital Pitié-Salpêtrière, UPMC, Sorbonne Universités, Paris, France
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22
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Vibert L, Daulny A, Jarriault S. Wound healing, cellular regeneration and plasticity: the elegans way. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2018; 62:491-505. [PMID: 29938761 PMCID: PMC6161810 DOI: 10.1387/ijdb.180123sj] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Regeneration and wound healing are complex processes that allow organs and tissues to regain their integrity and functionality after injury. Wound healing, a key property of epithelia, involves tissue closure that in some cases leads to scar formation. Regeneration, a process rather limited in mammals, is the capacity to regrow (parts of) an organ or a tissue, after damage or amputation. What are the properties of organs and the features of tissue permitting functional regrowth and repair? What are the cellular and molecular mechanisms underlying these processes? These questions are crucial both in fundamental and applied contexts, with important medical implications. The mechanisms and cells underlying tissue repair have thus been the focus of intense investigation. The last decades have seen rapid progress in the domain and new models emerging. Here, we review the fundamental advances and the perspectives that the use of C. elegans as a model have brought to the mechanisms of wound healing and cellular plasticity, axon regeneration and transdifferentiation in vivo.
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Affiliation(s)
- Laura Vibert
- Department of Development and Stem Cells, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), CNRS UMR 7104/INSERM U1258, Université de Strasbourg, Strasbourg, France
| | - Anne Daulny
- Department of Development and Stem Cells, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), CNRS UMR 7104/INSERM U1258, Université de Strasbourg, Strasbourg, France
| | - Sophie Jarriault
- Department of Development and Stem Cells, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), CNRS UMR 7104/INSERM U1258, Université de Strasbourg, Strasbourg, France
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23
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Thomson SE, Charalambous C, Smith CA, Tsimbouri PM, Déjardin T, Kingham PJ, Hart AM, Riehle MO. Microtopographical cues promote peripheral nerve regeneration via transient mTORC2 activation. Acta Biomater 2017; 60:220-231. [PMID: 28754648 PMCID: PMC5593812 DOI: 10.1016/j.actbio.2017.07.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/04/2017] [Accepted: 07/20/2017] [Indexed: 12/16/2022]
Abstract
Despite microsurgical repair, recovery of function following peripheral nerve injury is slow and often incomplete. Outcomes could be improved by an increased understanding of the molecular biology of regeneration and by translation of experimental bioengineering strategies. Topographical cues have been shown to be powerful regulators of the rate and directionality of neurite regeneration, and in this study we investigated the downstream molecular effects of linear micropatterned structures in an organotypic explant model. Linear topographical cues enhanced neurite outgrowth and our results demonstrated that the mTOR pathway is important in regulating these responses. mTOR gene expression peaked between 48 and 72 h, coincident with the onset of rapid neurite outgrowth and glial migration, and correlated with neurite length at 48 h. mTOR protein was located to glia and in a punctate distribution along neurites. mTOR levels peaked at 72 h and were significantly increased by patterned topography (p < 0.05). Furthermore, the topographical cues could override pharmacological inhibition. Downstream phosphorylation assays and inhibition of mTORC1 using rapamycin highlighted mTORC2 as an important mediator, and more specific therapeutic target. Quantitative immunohistochemistry confirmed the presence of the mTORC2 component rictor at the regenerating front where it co-localised with F-actin and vinculin. Collectively, these results provide a deeper understanding of the mechanism of action of topography on neural regeneration, and support the incorporation of topographical patterning in combination with pharmacological mTORC2 potentiation within biomaterial constructs used to repair peripheral nerves. Statement of Significance Peripheral nerve injury is common and functionally devastating. Despite microsurgical repair, healing is slow and incomplete, with lasting functional deficit. There is a clear need to translate bioengineering approaches and increase our knowledge of the molecular processes controlling nerve regeneration to improve the rate and success of healing. Topographical cues are powerful determinants of neurite outgrowth and represent a highly translatable engineering strategy. Here we demonstrate, for the first time, that microtopography potentiates neurite outgrowth via the mTOR pathway, with the mTORC2 subtype being of particular importance. These results give further evidence for the incorporation of microtopographical cues into peripheral nerve regeneration conduits and indicate that mTORC2 may be a suitable therapeutic target to potentiate nerve regeneration.
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24
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Hisamoto N, Matsumoto K. Signal transduction cascades in axon regeneration: insights from C. elegans. Curr Opin Genet Dev 2017; 44:54-60. [PMID: 28213159 DOI: 10.1016/j.gde.2017.01.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/13/2017] [Accepted: 01/26/2017] [Indexed: 02/07/2023]
Abstract
Axon regeneration after nerve injury is a conserved biological process in many animals, including humans. The nematode Caenorhabditis elegans (C. elegans) has recently emerged as a genetically tractable model for studying regenerative responses in neurons. Extensive studies over several years using this organism have revealed a number of intrinsic and extrinsic signal transduction cascades that regulate axon regeneration, and these are found to be conserved from worms to humans. Further studies have demonstrated that these cascades consist of several signaling networks that ultimately merge into the c-Jun N-terminal kinase (JNK) cascade. In this review, we describe some recent insights into the signaling cascades controlling axon regeneration in C. elegans and describe their conserved roles in other organisms including mammals.
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Affiliation(s)
- Naoki Hisamoto
- Department of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Kunihiro Matsumoto
- Department of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
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25
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O'Donovan KJ. Intrinsic Axonal Growth and the Drive for Regeneration. Front Neurosci 2016; 10:486. [PMID: 27833527 PMCID: PMC5081384 DOI: 10.3389/fnins.2016.00486] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/10/2016] [Indexed: 02/01/2023] Open
Abstract
Following damage to the adult nervous system in conditions like stroke, spinal cord injury, or traumatic brain injury, many neurons die and most of the remaining spared neurons fail to regenerate. Injured neurons fail to regrow both because of the inhibitory milieu in which they reside as well as a loss of the intrinsic growth capacity of the neurons. If we are to develop effective therapeutic interventions that promote functional recovery for the devastating injuries described above, we must not only better understand the molecular mechanisms of developmental axonal growth in hopes of re-activating these pathways in the adult, but at the same time be aware that re-activation of adult axonal growth may proceed via distinct mechanisms. With this knowledge in hand, promoting adult regeneration of central nervous system neurons can become a more tractable and realistic therapeutic endeavor.
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Affiliation(s)
- Kevin J O'Donovan
- Department of Chemistry and Life Science, United States Military Academy West Point, NY, USA
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26
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Egawa N, Lok J, Washida K, Arai K. Mechanisms of Axonal Damage and Repair after Central Nervous System Injury. Transl Stroke Res 2016; 8:14-21. [PMID: 27566737 DOI: 10.1007/s12975-016-0495-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 08/14/2016] [Accepted: 08/16/2016] [Indexed: 01/19/2023]
Abstract
Central nervous system (CNS) injury initiates spatial and temporal neurodegeneration. Under pathologic conditions, damaged glial cells cannot supply sufficient metabolites to neurons, leading to energy deficiency for neuronal axons. The widespread disruption of cellular membranes causes disturbed intracellular signaling via dysregulated ionic gradients in neurons. Although several deleterious cascades are activated during the acute phase of CNS injury, some compensatory responses may tend to promote axonal repair during the chronic/remodeling phase. Because it may not be easy to block all multifactorial neurodegenerative pathways after CNS injury, supporting or boosting endogenous regenerative mechanisms would be an important therapeutic approach for CNS diseases. In this mini-review, we briefly but broadly introduce basic mechanisms that trigger axonal degeneration and then discuss potential targets for promoting axonal regeneration after CNS injury.
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Affiliation(s)
- Naohiro Egawa
- Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, MGH East 149-2401, Charlestown, MA, 02129, USA
| | - Josephine Lok
- Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, MGH East 149-2401, Charlestown, MA, 02129, USA.,Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Kazuo Washida
- Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, MGH East 149-2401, Charlestown, MA, 02129, USA
| | - Ken Arai
- Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, MGH East 149-2401, Charlestown, MA, 02129, USA.
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27
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Byrne AB, Hammarlund M. Axon regeneration in C. elegans: Worming our way to mechanisms of axon regeneration. Exp Neurol 2016; 287:300-309. [PMID: 27569538 DOI: 10.1016/j.expneurol.2016.08.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 08/19/2016] [Accepted: 08/24/2016] [Indexed: 12/12/2022]
Abstract
How axons repair themselves after injury is a fundamental question in neurobiology. With its conserved genome, relatively simple nervous system, and transparent body, C. elegans has recently emerged as a productive model to uncover the cellular mechanisms that regulate and execute axon regeneration. In this review, we discuss the strengths and weaknesses of the C. elegans model of regeneration. We explore the technical advances that enable the use of C. elegans for in vivo regeneration studies, review findings in C. elegans that have contributed to our understanding of the regeneration response across species, discuss the potential of C. elegans research to provide insight into mechanisms that function in the injured mammalian nervous system, and present potential future directions of axon regeneration research using C. elegans.
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Affiliation(s)
- Alexandra B Byrne
- Department of Genetics, Yale University School of Medicine, New Haven, CT, United States; Department of Neuroscience, Yale University School of Medicine, New Haven, CT, United States
| | - Marc Hammarlund
- Department of Genetics, Yale University School of Medicine, New Haven, CT, United States; Department of Neuroscience, Yale University School of Medicine, New Haven, CT, United States.
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28
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Blondeau A, Lucier JF, Matteau D, Dumont L, Rodrigue S, Jacques PÉ, Blouin R. Dual leucine zipper kinase regulates expression of axon guidance genes in mouse neuronal cells. Neural Dev 2016; 11:13. [PMID: 27468987 PMCID: PMC4965899 DOI: 10.1186/s13064-016-0068-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 07/25/2016] [Indexed: 11/10/2022] Open
Abstract
Background Recent genetic studies in model organisms, such as Drosophila, C. elegans and mice, have highlighted a critical role for dual leucine zipper kinase (DLK) in neural development and axonal responses to injury. However, exactly how DLK fulfills these functions remains to be determined. Using RNA-seq profiling, we evaluated the global changes in gene expression that are caused by shRNA-mediated knockdown of endogenous DLK in differentiated Neuro-2a neuroblastoma cells. Results Our analysis led to the identification of numerous up- and down-regulated genes, among which several were found to be associated with system development and axon guidance according to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, respectively. Because of their importance in axonal growth, pruning and regeneration during development and adult life, we then examined by quantitative RT-PCR the mRNA expression levels of the identified axon guidance genes in DLK-depleted cells. Consistent with the RNA-seq data, our results confirmed that loss of DLK altered expression of the genes encoding neuropilin 1 (Nrp1), plexin A4 (Plxna4), Eph receptor A7 (Epha7), Rho family GTPase 1 (Rnd1) and semaphorin 6B (Sema6b). Interestingly, this regulation of Nrp1 and Plxna4 mRNA expression by DLK in Neuro-2a cells was also reflected at the protein level, implicating DLK in the modulation of the function of these axon guidance molecules. Conclusions Collectively, these results provide the first evidence that axon guidance genes are downstream targets of the DLK signaling pathway, which through their regulation probably modulates neuronal cell development, structure and function. Electronic supplementary material The online version of this article (doi:10.1186/s13064-016-0068-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andréanne Blondeau
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada
| | - Jean-François Lucier
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada
| | - Dominick Matteau
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada
| | - Lauralyne Dumont
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada
| | - Sébastien Rodrigue
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada
| | - Pierre-Étienne Jacques
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada.,Département d'informatique, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.,Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, Canada
| | - Richard Blouin
- Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. de l'Université, Sherbrooke, Québec, J1K 2R1, Canada.
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29
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30
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Abstract
The capacity of an axon to regenerate is regulated by its external environment and by cell-intrinsic factors. Studies in a variety of organisms suggest that alterations in axonal microtubule (MT) dynamics have potent effects on axon regeneration. We review recent findings on the regulation of MT dynamics during axon regeneration, focusing on the nematode Caenorhabditis elegans. In C. elegans the dual leucine zipper kinase (DLK) promotes axon regeneration, whereas the exchange factor for Arf6 (EFA-6) inhibits axon regeneration. Both DLK and EFA-6 respond to injury and control axon regeneration in part via MT dynamics. How the DLK and EFA-6 pathways are related is a topic of active investigation, as is the mechanism by which EFA-6 responds to axonal injury. We evaluate potential candidates, such as the MT affinity-regulating kinase PAR-1/MARK, in regulation of EFA-6 and axonal MT dynamics in regeneration.
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Affiliation(s)
- Ngang Heok Tang
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Andrew D Chisholm
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
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31
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Novel DLK-independent neuronal regeneration in Caenorhabditis elegans shares links with activity-dependent ectopic outgrowth. Proc Natl Acad Sci U S A 2016; 113:E2852-60. [PMID: 27078101 DOI: 10.1073/pnas.1600564113] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
During development, a neuron transitions from a state of rapid growth to a stable morphology, and neurons within the adult mammalian CNS lose their ability to effectively regenerate in response to injury. Here, we identify a novel form of neuronal regeneration, which is remarkably independent of DLK-1/DLK, KGB-1/JNK, and other MAPK signaling factors known to mediate regeneration in Caenorhabditis elegans, Drosophila, and mammals. This DLK-independent regeneration in C. elegans has direct genetic and molecular links to a well-studied form of endogenous activity-dependent ectopic axon outgrowth in the same neuron type. Both neuron outgrowth types are triggered by physical lesion of the sensory dendrite or mutations disrupting sensory activity, calcium signaling, or genes that restrict outgrowth during neuronal maturation, such as SAX-1/NDR kinase or UNC-43/CaMKII. These connections suggest that ectopic outgrowth represents a powerful platform for gene discovery in neuronal regeneration. Moreover, we note numerous similarities between C. elegans DLK-independent regeneration and lesion conditioning, a phenomenon producing robust regeneration in the mammalian CNS. Both regeneration types are triggered by lesion of a sensory neurite via reduction of neuronal activity and enhanced by disrupting L-type calcium channels or elevating cAMP. Taken as a whole, our study unites disparate forms of neuronal outgrowth to uncover fresh molecular insights into activity-dependent control of the adult nervous system's intrinsic regenerative capacity.
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32
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Grill B, Murphey RK, Borgen MA. The PHR proteins: intracellular signaling hubs in neuronal development and axon degeneration. Neural Dev 2016; 11:8. [PMID: 27008623 PMCID: PMC4806438 DOI: 10.1186/s13064-016-0063-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/15/2016] [Indexed: 11/10/2022] Open
Abstract
During development, a coordinated and integrated series of events must be accomplished in order to generate functional neural circuits. Axons must navigate toward target cells, build synaptic connections, and terminate outgrowth. The PHR proteins (consisting of mammalian Phr1/MYCBP2, Drosophila Highwire and C. elegans RPM-1) function in each of these events in development. Here, we review PHR function across species, as well as the myriad of signaling pathways PHR proteins regulate. These findings collectively suggest that the PHR proteins are intracellular signaling hubs, a concept we explore in depth. Consistent with prominent developmental functions, genetic links have begun to emerge between PHR signaling networks and neurodevelopmental disorders, such as autism, schizophrenia and intellectual disability. Finally, we discuss the recent and important finding that PHR proteins regulate axon degeneration, which has further heightened interest in this fascinating group of molecules.
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Affiliation(s)
- Brock Grill
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA.
| | - Rodney K Murphey
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, 33458, USA
| | - Melissa A Borgen
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA
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33
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Nichols ALA, Meelkop E, Linton C, Giordano-Santini R, Sullivan RK, Donato A, Nolan C, Hall DH, Xue D, Neumann B, Hilliard MA. The Apoptotic Engulfment Machinery Regulates Axonal Degeneration in C. elegans Neurons. Cell Rep 2016; 14:1673-1683. [PMID: 26876181 PMCID: PMC4821572 DOI: 10.1016/j.celrep.2016.01.050] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/23/2015] [Accepted: 01/13/2016] [Indexed: 01/31/2023] Open
Abstract
Axonal degeneration is a characteristic feature of neurodegenerative disease and nerve injury. Here, we characterize axonal degeneration in Caenorhabditis elegans neurons following laser-induced axotomy. We show that this process proceeds independently of the WLD(S) and Nmnat pathway and requires the axonal clearance machinery that includes the conserved transmembrane receptor CED-1/Draper, the adaptor protein CED-6, the guanine nucleotide exchange factor complex Crk/Mbc/dCed-12 (CED-2/CED-5/CED-12), and the small GTPase Rac1 (CED-10). We demonstrate that CED-1 and CED-6 function non-cell autonomously in the surrounding hypodermis, which we show acts as the engulfing tissue for the severed axon. Moreover, we establish a function in this process for CED-7, an ATP-binding cassette (ABC) transporter, and NRF-5, a lipid-binding protein, both associated with release of lipid-vesicles during apoptotic cell clearance. Thus, our results reveal the existence of a WLD(S)/Nmnat-independent axonal degeneration pathway, conservation of the axonal clearance machinery, and a function for CED-7 and NRF-5 in this process.
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Affiliation(s)
- Annika L A Nichols
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ellen Meelkop
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Casey Linton
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert K Sullivan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Alessandra Donato
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cara Nolan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David H Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Brent Neumann
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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34
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Li C, Hisamoto N, Matsumoto K. Axon Regeneration Is Regulated by Ets-C/EBP Transcription Complexes Generated by Activation of the cAMP/Ca2+ Signaling Pathways. PLoS Genet 2015; 11:e1005603. [PMID: 26484536 PMCID: PMC4618690 DOI: 10.1371/journal.pgen.1005603] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 09/23/2015] [Indexed: 11/19/2022] Open
Abstract
The ability of specific neurons to regenerate their axons after injury is governed by cell-intrinsic regeneration pathways. In Caenorhabditis elegans, the JNK and p38 MAPK pathways are important for axon regeneration. Axonal injury induces expression of the svh-2 gene encoding a receptor tyrosine kinase, stimulation of which by the SVH-1 growth factor leads to activation of the JNK pathway. Here, we identify ETS-4 and CEBP-1, related to mammalian Ets and C/EBP, respectively, as transcriptional activators of svh-2 expression following axon injury. ETS-4 and CEBP-1 function downstream of the cAMP and Ca2+-p38 MAPK pathways, respectively. We show that PKA-dependent phosphorylation of ETS-4 promotes its complex formation with CEBP-1. Furthermore, activation of both cAMP and Ca2+ signaling is required for activation of svh-2 expression. Thus, the cAMP/Ca2+ signaling pathways cooperatively activate the JNK pathway, which then promotes axon regeneration.
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Affiliation(s)
- Chun Li
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Naoki Hisamoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
- * E-mail: (NH); (KM)
| | - Kunihiro Matsumoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
- * E-mail: (NH); (KM)
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35
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DeFrancesco-Lisowitz A, Lindborg JA, Niemi JP, Zigmond RE. The neuroimmunology of degeneration and regeneration in the peripheral nervous system. Neuroscience 2015; 302:174-203. [PMID: 25242643 PMCID: PMC4366367 DOI: 10.1016/j.neuroscience.2014.09.027] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/08/2014] [Accepted: 09/10/2014] [Indexed: 12/25/2022]
Abstract
Peripheral nerves regenerate following injury due to the effective activation of the intrinsic growth capacity of the neurons and the formation of a permissive pathway for outgrowth due to Wallerian degeneration (WD). WD and subsequent regeneration are significantly influenced by various immune cells and the cytokines they secrete. Although macrophages have long been known to play a vital role in the degenerative process, recent work has pointed to their importance in influencing the regenerative capacity of peripheral neurons. In this review, we focus on the various immune cells, cytokines, and chemokines that make regeneration possible in the peripheral nervous system, with specific attention placed on the role macrophages play in this process.
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Affiliation(s)
| | - J A Lindborg
- Department of Neurosciences, Case Western Reserve University, Cleveland OH 44106-4975
| | - J P Niemi
- Department of Neurosciences, Case Western Reserve University, Cleveland OH 44106-4975
| | - R E Zigmond
- Department of Neurosciences, Case Western Reserve University, Cleveland OH 44106-4975
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36
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Valakh V, Frey E, Babetto E, Walker LJ, DiAntonio A. Cytoskeletal disruption activates the DLK/JNK pathway, which promotes axonal regeneration and mimics a preconditioning injury. Neurobiol Dis 2015; 77:13-25. [PMID: 25726747 DOI: 10.1016/j.nbd.2015.02.014] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 01/12/2015] [Accepted: 02/15/2015] [Indexed: 10/23/2022] Open
Abstract
Nerve injury can lead to axonal regeneration, axonal degeneration, and/or neuronal cell death. Remarkably, the MAP3K dual leucine zipper kinase, DLK, promotes each of these responses, suggesting that DLK is a sensor of axon injury. In Drosophila, mutations in proteins that stabilize the actin and microtubule cytoskeletons activate the DLK pathway, suggesting that DLK may be activated by cytoskeletal disruption. Here we test this model in mammalian sensory neurons. We find that pharmacological agents designed to disrupt either the actin or microtubule cytoskeleton activate the DLK pathway, and that activation is independent of calcium influx or induction of the axon degeneration program. Moreover, activation of the DLK pathway by targeting the cytoskeleton induces a pro-regenerative state, enhancing axon regeneration in response to a subsequent injury in a process akin to preconditioning. This highlights the potential utility of activating the DLK pathway as a method to improve axon regeneration. Moreover, DLK is required for these responses to cytoskeletal perturbations, suggesting that DLK functions as a key neuronal sensor of cytoskeletal damage.
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Affiliation(s)
- Vera Valakh
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Erin Frey
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Elisabetta Babetto
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Lauren J Walker
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Aaron DiAntonio
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA.
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37
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Lu W, Lakonishok M, Gelfand VI. Kinesin-1-powered microtubule sliding initiates axonal regeneration in Drosophila cultured neurons. Mol Biol Cell 2015; 26:1296-307. [PMID: 25657321 PMCID: PMC4454177 DOI: 10.1091/mbc.e14-10-1423] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Microtubule sliding drives initial axon regeneration in Drosophila neurons. Axotomy leads to fast calcium influx and subsequent microtubule reorganization. Kinesin-1 heavy chain drives the sliding of antiparallel microtubules to power axonal regrowth, and the JNK pathway promotes axonal regeneration by enhancing microtubule sliding. Understanding the mechanism underlying axon regeneration is of great practical importance for developing therapeutic treatment for traumatic brain and spinal cord injuries. Dramatic cytoskeleton reorganization occurs at the injury site, and microtubules have been implicated in the regeneration process. Previously we demonstrated that microtubule sliding by conventional kinesin (kinesin-1) is required for initiation of neurite outgrowth in Drosophila embryonic neurons and that sliding is developmentally down-regulated when neurite outgrowth is completed. Here we report that mechanical axotomy of Drosophila neurons in culture triggers axonal regeneration and regrowth. Regenerating neurons contain actively sliding microtubules; this sliding, like sliding during initial neurite outgrowth, is driven by kinesin-1 and is required for axonal regeneration. The injury induces a fast spike of calcium, depolymerization of microtubules near the injury site, and subsequent formation of local new microtubule arrays with mixed polarity. These events are required for reactivation of microtubule sliding at the initial stages of regeneration. Furthermore, the c-Jun N-terminal kinase pathway promotes regeneration by enhancing microtubule sliding in injured mature neurons.
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Affiliation(s)
- Wen Lu
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Margot Lakonishok
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
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38
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Liu X, Williams PR, He Z. SOCS3: a common target for neuronal protection and axon regeneration after spinal cord injury. Exp Neurol 2014; 263:364-7. [PMID: 25446722 DOI: 10.1016/j.expneurol.2014.10.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 10/30/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Xuefeng Liu
- F.M. Kirby Neurobiology Center, Children's Hospital of Boston, Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Philip R Williams
- F.M. Kirby Neurobiology Center, Children's Hospital of Boston, Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Children's Hospital of Boston, Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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39
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Abstract
Motoneuron death after transection of the axons (axotomy) in neonates is believed to share the same mechanistic bases as naturally occurring programmed cell death during development. The c-Jun N-terminal kinase pathway is activated in both forms of motoneuron death, but it remains unknown to what extent these two forms of motoneuron death depend on this pathway and which upstream kinases are involved. We found that numbers of facial motoneurons are doubled in neonatal mice deficient in either ZPK/DLK (zipper protein kinase, also known as dual leucine zipper kinase), a mitogen-activated protein kinase kinase kinase, or in MKK4/MAP2K4, a mitogen-activated protein kinase kinase directly downstream of ZPK/DLK, and that the facial motoneurons in those mutant mice are completely resistant to axotomy-induced death. Conditional deletion of MKK4/MAP2K4 in neurons further suggested that ZPK/DLK and MKK4/MAP2K4-dependent mechanisms underlying axotomy-induced death are motoneuron autonomous. Nevertheless, quantitative analysis of facial motoneurons during embryogenesis revealed that both ZPK/DLK and MKK4/MAP2K4-dependent and -independent mechanisms contribute to developmental elimination of excess motoneurons. In contrast to MKK4/MAP2K4, mice lacking MKK7/MAP2K7, another mitogen-activated protein kinase kinase directly downstream of ZPK/DLK, conditionally in neurons did not have excess facial motoneurons. However, some MKK7/MAP2K7-deficient facial motoneurons were resistant to axotomy-induced death, indicating a synergistic effect of MKK7/MAP2K7 on axotomy-induced death of these facial motoneurons. Together, our study provides compelling evidence for the pivotal roles of the ZPK/DLK and MKK4/MAP2K4-dependent mechanism in axotomy-induced motoneuron death in neonates and also demonstrates that axotomy-induced motoneuron death is not identical to developmental motoneuron death with respect to the involvement of ZPK/DLK, MKK4/MAP2K4 and MKK7/MAP2K7.
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RPM-1 uses both ubiquitin ligase and phosphatase-based mechanisms to regulate DLK-1 during neuronal development. PLoS Genet 2014; 10:e1004297. [PMID: 24810406 PMCID: PMC4014440 DOI: 10.1371/journal.pgen.1004297] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 02/21/2014] [Indexed: 01/06/2023] Open
Abstract
The Pam/Highwire/RPM-1 (PHR) proteins are key regulators of neuronal development that function in axon extension and guidance, termination of axon outgrowth, and synapse formation. Outside of development, the PHR proteins also regulate axon regeneration and Wallerian degeneration. The PHR proteins function in part by acting as ubiquitin ligases that degrade the Dual Leucine zipper-bearing Kinase (DLK). Here, we show that the Caenorhabditis elegans PHR protein, Regulator of Presynaptic Morphology 1 (RPM-1), also utilizes a phosphatase-based mechanism to regulate DLK-1. Using mass spectrometry, we identified Protein Phosphatase Magnesium/Manganese dependent 2 (PPM-2) as a novel RPM-1 binding protein. Genetic, transgenic, and biochemical studies indicated that PPM-2 functions coordinately with the ubiquitin ligase activity of RPM-1 and the F-box protein FSN-1 to negatively regulate DLK-1. PPM-2 acts on S874 of DLK-1, a residue implicated in regulation of DLK-1 binding to a short, inhibitory isoform of DLK-1 (DLK-1S). Our study demonstrates that PHR proteins function through both phosphatase and ubiquitin ligase mechanisms to inhibit DLK. Thus, PHR proteins are potentially more accurate and sensitive regulators of DLK than originally thought. Our results also highlight an important and expanding role for the PP2C phosphatase family in neuronal development. The molecular mechanisms that govern formation of functional synaptic connections are central to brain development and function. We have used the nematode C. elegans to explore the mechanism of how the intracellular signaling protein RPM-1 regulates neuronal development. Using a combination of proteomic, genetic, transgenic, and biochemical approaches we have shown that RPM-1 functions through a PP2C phosphatase, PPM-2, to regulate the activity of a MAP3 kinase, DLK-1. Our results indicate that a combination of PPM-2 phosphatase activity and RPM-1 ubiquitin ligase activity inhibit DLK-1.
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41
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Abstract
The ability of injured axons to regenerate declines with age, yet the mechanisms that regulate axon regeneration in response to age are not known. Here we show that axon regeneration in aging C. elegans motor neurons is inhibited by the conserved insulin/IGF1 receptor DAF-2. DAF-2's function in regeneration is mediated by intrinsic neuronal activity of the forkhead transcription factor DAF-16/FOXO. DAF-16 regulates regeneration independently of lifespan, indicating that neuronal aging is an intrinsic, neuron-specific, and genetically regulated process. In addition, we found that DAF-18/PTEN inhibits regeneration independently of age and FOXO signaling via the TOR pathway. Finally, DLK-1, a conserved regulator of regeneration, is downregulated by insulin/IGF1 signaling, bound by DAF-16 in neurons, and required for both DAF-16- and DAF-18-mediated regeneration. Together, our data establish that insulin signaling specifically inhibits regeneration in aging adult neurons and that this mechanism is independent of PTEN and TOR.
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42
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Abstract
The extensive lengths of neuronal processes necessitate efficient mechanisms for communication with the cell body. Neuronal regeneration after nerve injury requires new transcription; thus, long-distance retrograde signalling from axonal lesion sites to the soma and nucleus is required. In recent years, considerable progress has been made in elucidating the mechanistic basis of this system. This has included the discovery of a priming role for early calcium waves; confirmation of central roles for mitogen-activated protein kinase signalling effectors, the importin family of nucleocytoplasmic transport factors and molecular motors such as dynein; and demonstration of the importance of local translation as a key regulatory mechanism. These recent findings provide a coherent mechanistic framework for axon-soma communication in the injured nerve and shed light on the integration of cytoplasmic and nuclear transport in all eukaryotic cells.
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Affiliation(s)
- Ida Rishal
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Mike Fainzilber
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
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43
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c-Jun N-terminal kinase phosphorylation of heterogeneous nuclear ribonucleoprotein K regulates vertebrate axon outgrowth via a posttranscriptional mechanism. J Neurosci 2013; 33:14666-80. [PMID: 24027268 DOI: 10.1523/jneurosci.4821-12.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
c-Jun N-terminal kinase (JNK) mediates cell signaling essential for axon outgrowth, but the associated substrates and underlying mechanisms are poorly understood. We identified in Xenopus laevis embryos a novel posttranscriptional mechanism whereby JNK regulates axonogenesis by phosphorylating a specific site on heterogeneous nuclear ribonucleoprotein K (hnRNP K). Both JNK inhibition and hnRNP K knockdown inhibited axon outgrowth and translation of hnRNP K-regulated cytoskeletal RNAs (tau and neurofilament medium), effects that were alleviated by expressing phosphomimetic, but not phosphodeficient, forms of hnRNP K. Immunohistochemical and biochemical analyses indicated that JNK phosphorylation of hnRNP K occurred within the cytoplasm and was necessary for the translational initiation of hnRNP K-targeted RNAs but not for hnRNP K intracellular localization or RNA binding. Thus, in addition to its known roles in transcription and cytoskeletal organization, JNK acts posttranscriptionally through hnRNP K to regulate translation of proteins crucial for axonogenesis.
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44
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Reina CP, Driscoll M, Gabel CV. Neuronal repair: Apoptotic proteins make good. WORM 2013; 2:e22285. [PMID: 24058867 PMCID: PMC3704441 DOI: 10.4161/worm.22285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 09/18/2012] [Indexed: 11/25/2022]
Abstract
The potential of the central nervous system (CNS) to regenerate is regulated by a complex interaction of neuronal intrinsic and extrinsic factors that remain poorly understood. Significant research has been dedicated to identifying these factors to facilitate design of therapies that will treat the functional impairment associated with CNS injuries. Over the last decade, the development of in vivo laser severing of single axons in C. elegans has established an invaluable model for the genetic identification of novel regeneration factors. In a recent study we report the unexpected identification of the core apoptotic proteins CED-4/Apaf-1 and the executioner caspase CED-3 as important factors that promote early events in regeneration in C. elegans. Other upstream regulators of apoptosis do not influence regeneration, indicating the existence of a novel mechanism for activation of CED-4 and CED-3 in neuronal repair. CED-4 and CED-3 function downstream of injury-induced calcium transients and appear to act through the conserved DLK-1 pathway to promote regeneration. We propose a working model for calcium-dependent localized activation of CED-4 and CED-3 caspase and discuss questions raised including mechanisms for spatially regulating activated CED-3 and the possible substrates that it might cleave to initiate regeneration.
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Affiliation(s)
- Christopher P Reina
- Department of Molecular Biology and Biochemistry; Rutgers University; Piscataway, NJ USA
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45
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Kurup N, Sharifnia P, Jin Y. Spatial and temporal dynamics of neurite regrowth. Curr Opin Neurobiol 2013; 23:1011-7. [PMID: 23856616 DOI: 10.1016/j.conb.2013.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/19/2013] [Accepted: 06/20/2013] [Indexed: 11/26/2022]
Abstract
Injury to mature neurites triggers a series of events that have both growth promoting and inhibitory roles. Recent evidence from a variety of experimental models has revealed new neuronal re-growth modulators. The action of these modulators must be precisely regulated both in time and space, and involves multiple cellular processes including retrograde signaling and local translation in the injured neurite. New genetic techniques, in combination with pharmacological approaches, have served to advance mechanistic dissection of neuronal response to injury. Better understanding of the spatio-temporal cues would greatly aid in the development of effective regenerative therapies.
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Affiliation(s)
- Naina Kurup
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
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46
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Saijilafu, Zhang BY, Zhou FQ. Signaling pathways that regulate axon regeneration. Neurosci Bull 2013; 29:411-20. [PMID: 23846598 DOI: 10.1007/s12264-013-1357-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 02/25/2013] [Indexed: 10/26/2022] Open
Abstract
Neurons in the mammalian central nervous system (CNS) cannot regenerate axons after injury. in contrast, neurons in the mammalian peripheral nervous system and in some non-mammalian models, such as C. elegans and Drosophila, are able to regrow axons. Understanding the molecular mechanisms by which these neurons support axon regeneration will help us find ways to enhance mammalian CNS axon regeneration. Here, recent studies in which signaling pathways regulating naturally-occurring axon regeneration that have been identified are reviewed, focusing on how these pathways control gene expression and growth-cone function during axon regeneration.
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Affiliation(s)
- Saijilafu
- Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland, USA
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47
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Abstract
Axon regeneration after damage is widespread in the animal kingdom, and the nematode Caenorhabditis elegans has recently emerged as a tractable model in which to study the genetics and cell biology of axon regrowth in vivo. A key early step in axon regrowth is the conversion of part of a mature axon shaft into a growth cone-like structure, involving coordinated alterations in the microtubule, actin, and neurofilament systems. Recent attention has focused on microtubule dynamics as a determinant of axon-regrowth ability in several organisms. Live imaging studies have begun to reveal how the microtubule cytoskeleton is remodeled after axon injury, as well as the regulatory pathways involved. The dual leucine zipper kinase family of mixed-lineage kinases has emerged as a critical sensor of axon damage and plays a key role in regulating microtubule dynamics in the damaged axon.
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Affiliation(s)
- Andrew D Chisholm
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, California 92093;
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48
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Tedeschi A, Bradke F. The DLK signalling pathway--a double-edged sword in neural development and regeneration. EMBO Rep 2013; 14:605-14. [PMID: 23681442 DOI: 10.1038/embor.2013.64] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/23/2013] [Indexed: 01/08/2023] Open
Abstract
Dual leucine zipper kinase (DLK), a mitogen-activated protein kinase kinase kinase, controls axon growth, apoptosis and neuron degeneration during neural development, as well as neurodegeneration after various insults to the adult nervous system. Interestingly, recent studies have also highlighted a role of DLK in promoting axon regeneration in diverse model systems. Invertebrates and vertebrates, cold- and warm-blooded animals, as well as central and peripheral mammalian nervous systems all differ in their ability to regenerate injured axons. Here, we discuss how DLK-dependent signalling regulates apparently contradictory functions during neural development and regeneration in different species. In addition, we outline strategies to fine-tune DLK function, either alone or together with other approaches, to promote axon regeneration in the adult mammalian central nervous system.
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Affiliation(s)
- Andrea Tedeschi
- Laboratory for Axon Growth & Regeneration, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
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49
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Tian X, Wu C. The role of ubiquitin-mediated pathways in regulating synaptic development, axonal degeneration and regeneration: insights from fly and worm. J Physiol 2013; 591:3133-43. [PMID: 23613532 DOI: 10.1113/jphysiol.2012.247940] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The covalent attachment of the 76 amino acid peptide ubiquitin to target proteins is a rapid and reversible modification that regulates protein stability, activity and localization. As such, it is a potent mechanism for sculpting the synapse. Recent studies from two genetic model organisms, Caenorhabditis elegans and Drosophila, have provided mounting evidence that ubiquitin-mediated pathways play important roles in controlling the presynaptic size, synaptic elimination and stabilization, synaptic transmission, postsynaptic receptor abundance, axonal degeneration and regeneration. While the data supporting the requirement of ubiquitination/deubiquitination for normal synaptic development and repair are compelling, detailed analyses of signalling events up- and downstream of these ubiquitin modifications are often challenging. This article summarizes the related research conducted in worms and flies and provides insight into the fundamental questions facing this field.
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Affiliation(s)
- Xiaolin Tian
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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50
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Functional genomic screening identifies dual leucine zipper kinase as a key mediator of retinal ganglion cell death. Proc Natl Acad Sci U S A 2013; 110:4045-50. [PMID: 23431148 DOI: 10.1073/pnas.1211284110] [Citation(s) in RCA: 195] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glaucoma, a major cause of blindness worldwide, is a neurodegenerative optic neuropathy in which vision loss is caused by loss of retinal ganglion cells (RGCs). To better define the pathways mediating RGC death and identify targets for the development of neuroprotective drugs, we developed a high-throughput RNA interference screen with primary RGCs and used it to screen the full mouse kinome. The screen identified dual leucine zipper kinase (DLK) as a key neuroprotective target in RGCs. In cultured RGCs, DLK signaling is both necessary and sufficient for cell death. DLK undergoes robust posttranscriptional up-regulation in response to axonal injury in vitro and in vivo. Using a conditional knockout approach, we confirmed that DLK is required for RGC JNK activation and cell death in a rodent model of optic neuropathy. In addition, tozasertib, a small molecule protein kinase inhibitor with activity against DLK, protects RGCs from cell death in rodent glaucoma and traumatic optic neuropathy models. Together, our results establish a previously undescribed drug/drug target combination in glaucoma, identify an early marker of RGC injury, and provide a starting point for the development of more specific neuroprotective DLK inhibitors for the treatment of glaucoma, nonglaucomatous forms of optic neuropathy, and perhaps other CNS neurodegenerations.
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