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Yeh JY, Chao HC, Hong CL, Hung YC, Tzou FY, Hsiao CT, Li JL, Chen WJ, Chou CT, Tsai YS, Liao YC, Lin YC, Lin S, Huang SY, Kennerson M, Lee YC, Chan CC. A missense mutation in human INSC causes peripheral neuropathy. EMBO Mol Med 2024; 16:1091-1114. [PMID: 38589651 PMCID: PMC11099080 DOI: 10.1038/s44321-024-00062-w] [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: 10/03/2023] [Revised: 03/08/2024] [Accepted: 03/15/2024] [Indexed: 04/10/2024] Open
Abstract
PAR3/INSC/LGN form an evolutionarily conserved complex required for asymmetric cell division in the developing brain, but its post-developmental function and disease relevance in the peripheral nervous system (PNS) remains unknown. We mapped a new locus for axonal Charcot-Marie-Tooth disease (CMT2) and identified a missense mutation c.209 T > G (p.Met70Arg) in the INSC gene. Modeling the INSCM70R variant in Drosophila, we showed that it caused proprioceptive defects in adult flies, leading to gait defects resembling those in CMT2 patients. Cellularly, PAR3/INSC/LGN dysfunction caused tubulin aggregation and necrotic neurodegeneration, with microtubule-stabilizing agents rescuing both morphological and functional defects of the INSCM70R mutation in the PNS. Our findings underscore the critical role of the PAR3/INSC/LGN machinery in the adult PNS and highlight a potential therapeutic target for INSC-associated CMT2.
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Affiliation(s)
- Jui-Yu Yeh
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Hua-Chuan Chao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Division of Neurology, Department of Medicine, Taoyuan General Hospital, Ministry of Health and Welfare, Taoyuan, Taiwan
| | - Cheng-Li Hong
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Yu-Chien Hung
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Fei-Yang Tzou
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Cheng-Tsung Hsiao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jeng-Lin Li
- Ph.D. Program in Translational Medicine, National Taiwan University and Academia Sinica, Taipei, Taiwan
- Department of Neurology, National Taiwan University Hospital Jinshan Branch, New Taipei City, Taiwan
| | - Wen-Jie Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Cheng Kung University and Academia Sinica, Tapiei, Taiwan
| | - Cheng-Ta Chou
- Department of Neurology, Neurological Institute, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Yu-Shuen Tsai
- Cancer and Immunology Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Chu Liao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
| | - Yu-Chun Lin
- Institute of Molecular Medicine, National Tsing Hua University, HsinChu, Taiwan
- Department of Medical Science, National Tsing Hua University, HsinChu, Taiwan
| | - Suewei Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Shu-Yi Huang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Marina Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney Local Health District, Concord, NSW, Australia
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
- Molecular Medicine Laboratory, Concord Hospital, Concord, NSW, Australia
| | - Yi-Chung Lee
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan.
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
- Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan.
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan.
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Bhattacharya MRC. A nerve-wracking buzz: lessons from Drosophila models of peripheral neuropathy and axon degeneration. Front Aging Neurosci 2023; 15:1166146. [PMID: 37614471 PMCID: PMC10442544 DOI: 10.3389/fnagi.2023.1166146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 07/24/2023] [Indexed: 08/25/2023] Open
Abstract
The degeneration of axons and their terminals occurs following traumatic, toxic, or genetically-induced insults. Common molecular mechanisms unite these disparate triggers to execute a conserved nerve degeneration cascade. In this review, we will discuss how models of peripheral nerve injury and neuropathy in Drosophila have led the way in advancing molecular understanding of axon degeneration and nerve injury pathways. Both neuron-intrinsic as well as glial responses to injury will be highlighted. Finally, we will offer perspective on what additional questions should be answered to advance these discoveries toward clinical interventions for patients with neuropathy.
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3
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Nguyen YDH, Yoshida H, Tran TM, Kamei K. Lipin knockdown in pan-neuron of Drosophila induces reduction of lifespan, deficient locomotive behavior, and abnormal morphology of motor neuron. Neuroreport 2023; 34:629-637. [PMID: 37470742 PMCID: PMC10344432 DOI: 10.1097/wnr.0000000000001936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
The Lipin family is evolutionarily conserved among insects and mammals, and its crucial roles in lipid synthesis and homeostatic control of energy balance have been well documented. This study investigated the function of Lipin in neuronal function and neurodegeneration. The GAL4/UAS system was used to knock down Lipin in the nervous system of Drosophila and investigate its behavioral and cellular phenotypes. The neuromuscular junction (NMJ) morphology was detected by immunostaining. Moreover, triacylglycerol and ATP levels were analyzed by using assay Kit. This study found that Lipin is localized almost in the cytoplasm of neurons in the brain lobe and ventral nerve cord, which are part of the central nervous system (CNS) of Drosophila melanogaster. Lipin knockdown larvae exhibit decreased locomotor activity, aberrant morphology of motor nerve terminals at NMJs, and reduced number and size of lipid droplets in the CNS. Furthermore, neuron-specific knockdown of Lipin leads to locomotor defects and a shortened lifespan, accompanied by a reduction in ATP levels in the adult stage. These results indicate that Lipin plays a crucial role in the CNS of Drosophila.
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Affiliation(s)
- Yen D H Nguyen
- Department of Functional Chemistry, Kyoto Institute of Technology
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan
| | - Thanh Men Tran
- Department of Biology, College of Natural Sciences, Cantho University, Cantho City, Vietnam
| | - Kaeko Kamei
- Department of Functional Chemistry, Kyoto Institute of Technology
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Li J, Xiao Q, Tan Q, Chen J, Sun L, Chen X, Chu Z, Wu H, Zhang Z, Li H, Zhao X, Zhang X. TgMORN2, a MORN Family Protein Involved in the Regulation of Endoplasmic Reticulum Stress in Toxoplasma gondii. Int J Mol Sci 2023; 24:10228. [PMID: 37373373 DOI: 10.3390/ijms241210228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
MORN proteins play a key role in the cytoskeletal structure of eukaryotes and are essential for the close arrangement of the endoplasmic reticulum and plasma membrane. A gene with nine MORN motifs (TGGT1_292120, named TgMORN2) was identified in the Toxoplasma gondii genome; it was presumed to belong to the MORN protein family and to have the function of forming the cytoskeleton, which affects the survival of T. gondii. However, the genetic deletion of MORN2 did not noticeably affect parasite growth and virulence. Using adjacent protein labeling techniques, we identified a network of TgMORN2 interactions, which mainly included endoplasmic reticulum stress (ER stress)-related proteins. In exploring these data, we found that the pathogenicity of the KO-TgMORN2 strain was significantly reduced in the case of tunicamycin-induced ER stress. Reticulon TgRTN (TGGT1_226430) and tubulin β-Tubulin were identified as interaction proteins of TgMORN2. Collectively, TgMORN2 plays a role in ER stress, which lays a foundation for further research on the function of the MORN protein in T. gondii.
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Affiliation(s)
- Jinxuan Li
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Qianqian Xiao
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Qianqian Tan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Junpeng Chen
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Lingyu Sun
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Xiao Chen
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Ziyu Chu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Hongxia Wu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Zhenzhao Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
| | - Hongmei Li
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai'an 271018, China
- Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Tai'an 271018, China
| | - Xiaomin Zhao
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai'an 271018, China
- Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Tai'an 271018, China
| | - Xiao Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai'an 271018, China
- Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Tai'an 271018, China
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Zhou J, Liu H, Zhang T, Wang Z, Zhang J, Lu Y, Li Z, Kong W, Zhao J. MORN4 protects cardiomyocytes against ischemic injury via MFN2-mediated mitochondrial dynamics and mitophagy. Free Radic Biol Med 2023; 196:156-170. [PMID: 36682578 DOI: 10.1016/j.freeradbiomed.2023.01.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/10/2023] [Accepted: 01/12/2023] [Indexed: 01/21/2023]
Abstract
The imbalance of mitochondrial fission and fusion dynamics causes ischemic cardiomyocyte apoptosis and heart injury by affecting mitophagy. Regulation of mitochondrial dynamics is an important therapeutic strategy for ischemic heart diseases. Considering the important roles of MORN motifs in heart diseases and chloroplast fission, we aimed to investigate the possible role of MORN repeat-containing protein 4 (MORN4) in the progression of myocardial infarction (MI), ischemic cardiomyocyte apoptosis, mitochondrial dynamics, and mitophagy. We found that in the MI mouse, MORN4 knockdown remarkably accelerated cardiac injury and fibrosis with deteriorating cardiac dysfunction. Sphingosylphosphorylcholine (SPC) alleviated ischemic cardiomyocyte apoptosis and heart injury through increased level of MORN4, indicating a vital function of MORN4 in heart with SPC used to clarify the molecular mechanisms underlying the functions of MORN4. Mechanistically, we found that MORN4 directly binds to MFN2 and promotes the phosphorylation of MFN2 S442 through Rho-associated protein kinase 2 (ROCK2), which mediates beneficial mitophagy induced by mitochondrial dynamics, while SPC promoted the binding of MORN4 and MFN2 and the process. Taken together, our data reveal a new perspective role of MORN4 in ischemic heart injury, and report that SPC could regulate myocardial mitochondrial homeostasis by activating the MORN4-MFN2 axis during the ischemic situation, this finding provides novel targets for improving myocardial ischemia tolerance and rescue of acute myocardial infarction.
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Affiliation(s)
- Jinrun Zhou
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Honghong Liu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Tianliang Zhang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China; Experimental Center for Medical Research, Weifang Medical University, Weifang, 261000, PR China
| | - Zhaohui Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Jiaojiao Zhang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Yao Lu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Zhiliang Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Weihua Kong
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China
| | - Jing Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, 266237, PR China.
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Towards a mechanistic understanding of axon transport and endocytic changes underlying paclitaxel-induced peripheral neuropathy. Exp Neurol 2023; 359:114258. [PMID: 36279934 DOI: 10.1016/j.expneurol.2022.114258] [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: 03/21/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 11/11/2022]
Abstract
Paclitaxel is a common chemotherapeutic agent widely used to treat solid cancer. However, it frequently causes peripheral sensory neuropathy, resulting in sensory abnormalities and pain in patients receiving treatment for cancer. As one of the most widely used chemotherapeutics, many preclinical studies on paclitaxel-induced peripheral neuropathy (PIPN) have been performed. Yet, there remain no effective options for treatment or prevention. Due to paclitaxel's ability to bind to and stabilize microtubules, a change in microtubule dynamics and subsequent disruptions in axonal transport has been predicted as a major underlying cause of paclitaxel-induced toxicity. However, the systemic understanding of PIPN mechanisms is largely incomplete, and various phenotypes have not been directly attributed to microtubule-related effects. This review aims to provide an overview of the literature involving paclitaxel-induced alteration in microtubule dynamics, axonal transport, and endocytic changes. It also aims to provide insights into how the microtubule-mediated hypothesis may relate to various phenotypes reported in PIPN studies.
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7
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Shin GJE, Abaci HE, Smith MC. Cellular Pathogenesis of Chemotherapy-Induced Peripheral Neuropathy: Insights From Drosophila and Human-Engineered Skin Models. FRONTIERS IN PAIN RESEARCH 2022; 3:912977. [PMID: 35875478 PMCID: PMC9304629 DOI: 10.3389/fpain.2022.912977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a highly prevalent and complex condition arising from chemotherapy cancer treatments. Currently, there are no treatment or prevention options in the clinic. CIPN accompanies pain-related sensory functions starting from the hands and feet. Studies focusing on neurons in vitro and in vivo models significantly advanced our understanding of CIPN pathological mechanisms. However, given the direct toxicity shown in both neurons and non-neuronal cells, effective in vivo or in vitro models that allow the investigation of neurons in their local environment are required. No single model can provide a complete solution for the required investigation, therefore, utilizing a multi-model approach would allow complementary advantages of different models and robustly validate findings before further translation. This review aims first to summarize approaches and insights from CIPN in vivo models utilizing small model organisms. We will focus on Drosophila melanogaster CIPN models that are genetically amenable and accessible to study neuronal interactions with the local environment in vivo. Second, we will discuss how these findings could be tested in physiologically relevant vertebrate models. We will focus on in vitro approaches using human cells and summarize the current understanding of engineering approaches that may allow the investigation of pathological changes in neurons and the skin environment.
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Affiliation(s)
- Grace Ji-eun Shin
- Zuckerman Mind Brain and Behavior Institute, Jerome L. Greene Science Center, Columbia University, New York, NY, United States
- *Correspondence: Grace Ji-eun Shin
| | - Hasan Erbil Abaci
- Department of Dermatology, Columbia University Medical Center, Saint Nicholas Avenue, New York, NY, United States
| | - Madison Christine Smith
- Zuckerman Mind Brain and Behavior Institute, Jerome L. Greene Science Center, Columbia University, New York, NY, United States
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8
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Zhou J, Liu H, Lin Y, Zhao J. Membrane Occupation and Recognition Nexus (MORN) motif controls protein localization and function. FEBS Lett 2022; 596:1839-1850. [PMID: 35568981 DOI: 10.1002/1873-3468.14378] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/23/2022] [Accepted: 05/07/2022] [Indexed: 11/06/2022]
Abstract
Membrane Occupation and Recognition Nexus (MORN) motif was first defined in 2000, when it was identified in the junctophilin protein family. Dozens of studies have been published ever since, mainly focusing on the function of a given MORN motif-containing protein in parasites, plants or animal cells. Proteins with MORN motifs are not only expressed in most animal and plant cell types but also significantly differ in their intracellular localization, suggesting that the MORN motifs may fulfil multiple physiological functions. Recent studies have found that MORN motif-containing proteins junctophilin 1/2 and MORN3 play a role in cardiac hypertrophy, skeletal muscle fiber stability and cancer. Hence, MORN motif-containing proteins may be exploited to develop improved treatments for various pathological conditions, such as cardiovascular diseases. Here, we review current research on MORN motif-containing proteins in different organisms and provide both ideas and approaches for follow-up exploration of their functions and applications.
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Affiliation(s)
- Jinrun Zhou
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
| | - Honghong Liu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
| | - Yushuang Lin
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
| | - Jing Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
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9
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Abstract
Junctophilins (JPHs) comprise a family of structural proteins that connect the plasma membrane to intracellular organelles such as the endo/sarcoplasmic reticulum. Tethering of these membrane structures results in the formation of highly organized subcellular junctions that play important signaling roles in all excitable cell types. There are four JPH isoforms, expressed primarily in muscle and neuronal cell types. Each JPH protein consists of 6 'membrane occupation and recognition nexus' (MORN) motifs, a joining region connecting these to another set of 2 MORN motifs, a putative alpha-helical region, a divergent region exhibiting low homology between JPH isoforms, and a carboxy-terminal transmembrane region anchoring into the ER/SR membrane. JPH isoforms play essential roles in developing and maintaining subcellular membrane junctions. Conversely, inherited mutations in JPH2 cause hypertrophic or dilated cardiomyopathy, while trinucleotide expansions in the JPH3 gene cause Huntington Disease-Like 2. Loss of JPH1 protein levels can cause skeletal myopathy, while loss of cardiac JPH2 levels causes heart failure and atrial fibrillation, among other disease. This review will provide a comprehensive overview of the JPH gene family, phylogeny, and evolutionary analysis of JPH genes and other MORN domain proteins. JPH biogenesis, membrane tethering, and binding partners will be discussed, as well as functional roles of JPH isoforms in excitable cells. Finally, potential roles of JPH isoform deficits in human disease pathogenesis will be reviewed.
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Affiliation(s)
- Stephan E Lehnart
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas, United States; Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Pediatrics (Cardiology), Neuroscience, and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, United States
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10
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Integrins protect sensory neurons in models of paclitaxel-induced peripheral sensory neuropathy. Proc Natl Acad Sci U S A 2021; 118:2006050118. [PMID: 33876743 DOI: 10.1073/pnas.2006050118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a major side effect from cancer treatment with no known method for prevention or cure in clinics. CIPN often affects unmyelinated nociceptive sensory terminals. Despite the high prevalence, molecular and cellular mechanisms that lead to CIPN are still poorly understood. Here, we used a genetically tractable Drosophila model and primary sensory neurons isolated from adult mouse to examine the mechanisms underlying CIPN and identify protective pathways. We found that chronic treatment of Drosophila larvae with paclitaxel caused degeneration and altered the branching pattern of nociceptive neurons, and reduced thermal nociceptive responses. We further found that nociceptive neuron-specific overexpression of integrins, which are known to support neuronal maintenance in several systems, conferred protection from paclitaxel-induced cellular and behavioral phenotypes. Live imaging and superresolution approaches provide evidence that paclitaxel treatment causes cellular changes that are consistent with alterations in endosome-mediated trafficking of integrins. Paclitaxel-induced changes in recycling endosomes precede morphological degeneration of nociceptive neuron arbors, which could be prevented by integrin overexpression. We used primary dorsal root ganglia (DRG) neuron cultures to test conservation of integrin-mediated protection. We show that transduction of a human integrin β-subunit 1 also prevented degeneration following paclitaxel treatment. Furthermore, endogenous levels of surface integrins were decreased in paclitaxel-treated mouse DRG neurons, suggesting that paclitaxel disrupts recycling in vertebrate sensory neurons. Altogether, our study supports conserved mechanisms of paclitaxel-induced perturbation of integrin trafficking and a therapeutic potential of restoring neuronal interactions with the extracellular environment to antagonize paclitaxel-induced toxicity in sensory neurons.
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11
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A Chemotherapy-Induced Peripheral Neuropathy Model in Drosophila melanogaster. Methods Mol Biol 2021. [PMID: 32524489 DOI: 10.1007/978-1-0716-0585-1_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Peripheral neuropathies are one of the largest categories of neurodegenerative diseases. To investigate their mechanisms, many in vitro and in vivo models can be employed. Here we present a protocol for the induction of chemotherapy-induced peripheral neuropathy (CIPN) in the Drosophila melanogaster (fruit fly) model system. Using a clinically relevant degeneration initiator, paclitaxel (taxol), it is possible to model many aspects of axon and dendrite degeneration while in a genetically tractable, in vivo system. In this protocol, we feed larval stage Drosophila neurotoxic chemotherapy drugs during the duration of larval development, followed by dissection and imaging of genetically labeled sensory axons and dendrites. Both axons and dendrites degenerate with taxol exposure. Our protocol should facilitate the adoption and expansion of this model to include other neurotoxic compounds.
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12
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Bush KM, Barber KR, Martinez JA, Tang SJ, Wairkar YP. Drosophila model of anti-retroviral therapy induced peripheral neuropathy and nociceptive hypersensitivity. Biol Open 2021; 10:bio.054635. [PMID: 33504470 PMCID: PMC7860131 DOI: 10.1242/bio.054635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The success of antiretroviral therapy (ART) has improved the survival of HIV-infected patients significantly. However, significant numbers of patients on ART whose HIV disease is well controlled show peripheral sensory neuropathy (PSN), suggesting that ART may cause PSN. Although the nucleoside reverse transcriptase inhibitors (NRTIs), one of the vital components of ART, are thought to contribute to PSN, the mechanisms underlying the PSN induced by NRTIs are unclear. In this study, we developed a Drosophila model of NRTI-induced PSN that recapitulates the salient features observed in patients undergoing ART: PSN and nociceptive hypersensitivity. Furthermore, our data demonstrate that pathways known to suppress PSN induced by chemotherapeutic drugs are ineffective in suppressing the PSN or nociception induced by NRTIs. Instead, we found that increased dynamics of a peripheral sensory neuron may possibly underlie NRTI-induced PSN and nociception. Our model provides a solid platform in which to investigate further mechanisms of ART-induced PSN and nociceptive hypersensitivity. This article has an associated First Person interview with the first author of the paper. Summary: Nucleoside reverse transcriptase inhibitors (NRTIs) that are important components of anti-retroviral therapies also cause peripheral sensory neuropathies (PSN). This article investigates ways in which NRTIs may cause PSN and outlines ways to better understand the mechanisms underlying it.
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Affiliation(s)
- Keegan M Bush
- Neuroscience Graduate Program, University of. Texas Medical Branch, Galveston, TX 77555, USA.,Mitchell Center for Neurodegenerative Diseases, Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Kara R Barber
- Neuroscience Graduate Program, University of. Texas Medical Branch, Galveston, TX 77555, USA.,Mitchell Center for Neurodegenerative Diseases, Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jade A Martinez
- Mitchell Center for Neurodegenerative Diseases, Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Shao-Jun Tang
- Neuroscience Graduate Program, University of. Texas Medical Branch, Galveston, TX 77555, USA .,Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Yogesh P Wairkar
- Neuroscience Graduate Program, University of. Texas Medical Branch, Galveston, TX 77555, USA .,Mitchell Center for Neurodegenerative Diseases, Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA.,Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX 77555, USA
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13
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Lee B, Cho Y. Experimental Model Systems for Understanding Human Axonal Injury Responses. Int J Mol Sci 2021; 22:E474. [PMID: 33418850 PMCID: PMC7824864 DOI: 10.3390/ijms22020474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/03/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
Neurons are structurally unique and have dendrites and axons that are vulnerable to injury. Some neurons in the peripheral nervous system (PNS) can regenerate their axons after injuries. However, most neurons in the central nervous system (CNS) fail to do so, resulting in irreversible neurological disorders. To understand the mechanisms of axon regeneration, various experimental models have been utilized in vivo and in vitro. Here, we collate the key experimental models that revealed the important mechanisms regulating axon regeneration and degeneration in different systems. We also discuss the advantages of experimenting with the rodent model, considering the application of these findings in understanding human diseases and for developing therapeutic methods.
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Affiliation(s)
| | - Yongcheol Cho
- Laboratory of Axon Regeneration & Degeneration, Department of Life Sciences, Korea University, Anam-ro 145, Seongbuk-gu, Seoul 02841, Korea;
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14
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Dannhäuser S, Lux TJ, Hu C, Selcho M, Chen JTC, Ehmann N, Sachidanandan D, Stopp S, Pauls D, Pawlak M, Langenhan T, Soba P, Rittner HL, Kittel RJ. Antinociceptive modulation by the adhesion GPCR CIRL promotes mechanosensory signal discrimination. eLife 2020; 9:e56738. [PMID: 32996461 PMCID: PMC7546736 DOI: 10.7554/elife.56738] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 09/17/2020] [Indexed: 12/17/2022] Open
Abstract
Adhesion-type GPCRs (aGPCRs) participate in a vast range of physiological processes. Their frequent association with mechanosensitive functions suggests that processing of mechanical stimuli may be a common feature of this receptor family. Previously, we reported that the Drosophila aGPCR CIRL sensitizes sensory responses to gentle touch and sound by amplifying signal transduction in low-threshold mechanoreceptors (Scholz et al., 2017). Here, we show that Cirl is also expressed in high-threshold mechanical nociceptors where it adjusts nocifensive behaviour under physiological and pathological conditions. Optogenetic in vivo experiments indicate that CIRL lowers cAMP levels in both mechanosensory submodalities. However, contrasting its role in touch-sensitive neurons, CIRL dampens the response of nociceptors to mechanical stimulation. Consistent with this finding, rat nociceptors display decreased Cirl1 expression during allodynia. Thus, cAMP-downregulation by CIRL exerts opposing effects on low-threshold mechanosensors and high-threshold nociceptors. This intriguing bipolar action facilitates the separation of mechanosensory signals carrying different physiological information.
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Affiliation(s)
- Sven Dannhäuser
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
| | - Thomas J Lux
- Center for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital WürzburgWürzburgGermany
| | - Chun Hu
- Neuronal Patterning and Connectivity, Center for Molecular Neurobiology, University Medical Center Hamburg-EppendorfHamburgGermany
| | - Mareike Selcho
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
| | - Jeremy T-C Chen
- Center for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital WürzburgWürzburgGermany
| | - Nadine Ehmann
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
| | - Divya Sachidanandan
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
| | - Sarah Stopp
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
| | - Dennis Pauls
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
| | - Matthias Pawlak
- Department of Neurophysiology, Institute of Physiology, University of WürzburgWürzburgGermany
| | - Tobias Langenhan
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig UniversityLeipzigGermany
| | - Peter Soba
- Neuronal Patterning and Connectivity, Center for Molecular Neurobiology, University Medical Center Hamburg-EppendorfHamburgGermany
| | - Heike L Rittner
- Center for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital WürzburgWürzburgGermany
| | - Robert J Kittel
- Department of Animal Physiology, Institute of Biology, Leipzig UniversityLeipzigGermany
- Carl-Ludwig-Institute for Physiology, Leipzig UniversityLeipzigGermany
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15
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Analyzing chemotherapy-induced peripheral neuropathy in vivo using non-mammalian animal models. Exp Neurol 2019; 323:113090. [PMID: 31669484 DOI: 10.1016/j.expneurol.2019.113090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 10/19/2019] [Accepted: 10/23/2019] [Indexed: 12/31/2022]
Abstract
Non-mammalian models of CIPN remain relatively sparse, but the knowledge gained from the few published studies suggest that these species have great potential to serve as a discovery platform for new pathways and underlying genetic mechanisms of CIPN. These models permit large-scale genetic and pharmacological screening, and they are highly suitable for in vivo imaging. CIPN phenotypes described in rodents have been confirmed in those models, and conversely, genetic players leading to axon de- and regeneration under conditions of chemotherapy treatment identified in these non-mammalian species have been validated in rodents. Given the need for non-traditional approaches with which to identify new CIPN mechanisms, these models bear a strong potential due to the conservation of basic mechanisms by which chemotherapeutic agents induce neurotoxicity.
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16
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Li J, Liu H, Raval MH, Wan J, Yengo CM, Liu W, Zhang M. Structure of the MORN4/Myo3a Tail Complex Reveals MORN Repeats as Protein Binding Modules. Structure 2019; 27:1366-1374.e3. [PMID: 31279628 DOI: 10.1016/j.str.2019.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/25/2019] [Accepted: 06/17/2019] [Indexed: 10/26/2022]
Abstract
Tandem repeats are basic building blocks for constructing proteins with diverse structures and functions. Compared with extensively studied α-helix-based tandem repeats such as ankyrin, tetratricopeptide, armadillo, and HEAT repeat proteins, relatively little is known about tandem repeat proteins formed by β hairpins. In this study, we discovered that the MORN repeats from MORN4 function as a protein binding module specifically recognizing a tail cargo binding region from Myo3a. The structure of the MORN4/Myo3a complex shows that MORN4 forms an extended single-layered β-sheet structure and uses a U-shaped groove to bind to the Myo3a tail with high affinity and specificity. Sequence and structural analyses further elucidated the unique sequence features for folding and target binding of MORN repeats. Our work establishes that the β-hairpin-based MORN repeats are protein-protein interaction modules.
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Affiliation(s)
- Jianchao Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Haiyang Liu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
| | - Manmeet H Raval
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Jun Wan
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Wei Liu
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China.
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China; Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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17
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Khuong TM, Wang QP, Manion J, Oyston LJ, Lau MT, Towler H, Lin YQ, Neely GG. Nerve injury drives a heightened state of vigilance and neuropathic sensitization in Drosophila. SCIENCE ADVANCES 2019; 5:eaaw4099. [PMID: 31309148 PMCID: PMC6620091 DOI: 10.1126/sciadv.aaw4099] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 06/10/2019] [Indexed: 06/10/2023]
Abstract
Injury can lead to devastating and often untreatable chronic pain. While acute pain perception (nociception) evolved more than 500 million years ago, virtually nothing is known about the molecular origin of chronic pain. Here we provide the first evidence that nerve injury leads to chronic neuropathic sensitization in insects. Mechanistically, peripheral nerve injury triggers a loss of central inhibition that drives escape circuit plasticity and neuropathic allodynia. At the molecular level, excitotoxic signaling within GABAergic (γ-aminobutyric acid) neurons required the acetylcholine receptor nAChRα1 and led to caspase-dependent death of GABAergic neurons. Conversely, disruption of GABA signaling was sufficient to trigger allodynia without injury. Last, we identified the conserved transcription factor twist as a critical downstream regulator driving GABAergic cell death and neuropathic allodynia. Together, we define how injury leads to allodynia in insects, and describe a primordial precursor to neuropathic pain may have been advantageous, protecting animals after serious injury.
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Affiliation(s)
- Thang M. Khuong
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Qiao-Ping Wang
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Guangzhou 510275, China
| | - John Manion
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Lisa J. Oyston
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Man-Tat Lau
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Harry Towler
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Yong Qi Lin
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - G. Gregory Neely
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
- Genome Editing Initiative, The University of Sydney, NSW 2006, Australia
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18
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Li J, Suda K, Ueoka I, Tanaka R, Yoshida H, Okada Y, Okamoto Y, Hiramatsu Y, Takashima H, Yamaguchi M. Neuron-specific knockdown of Drosophila HADHB induces a shortened lifespan, deficient locomotive ability, abnormal motor neuron terminal morphology and learning disability. Exp Cell Res 2019; 379:150-158. [DOI: 10.1016/j.yexcr.2019.03.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 03/29/2019] [Accepted: 03/30/2019] [Indexed: 01/03/2023]
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19
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Malacrida A, Meregalli C, Rodriguez-Menendez V, Nicolini G. Chemotherapy-Induced Peripheral Neuropathy and Changes in Cytoskeleton. Int J Mol Sci 2019; 20:E2287. [PMID: 31075828 PMCID: PMC6540147 DOI: 10.3390/ijms20092287] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 12/23/2022] Open
Abstract
Despite the different antineoplastic mechanisms of action, peripheral neurotoxicity induced by all chemotherapy drugs (anti-tubulin agents, platinum compounds, proteasome inhibitors, thalidomide) is associated with neuron morphological changes ascribable to cytoskeleton modifications. The "dying back" degeneration of distal terminals (sensory nerves) of dorsal root ganglia sensory neurons, observed in animal models, in in vitro cultures and biopsies of patients is the most evident hallmark of the perturbation of the cytoskeleton. On the other hand, in highly polarized cells like neurons, the cytoskeleton carries out its role not only in axons but also has a fundamental role in dendrite plasticity and in the organization of soma. In the literature, there are many studies focused on the antineoplastic-induced alteration of microtubule organization (and consequently, fast axonal transport defects) while very few studies have investigated the effect of the different classes of drugs on microfilaments, intermediate filaments and associated proteins. Therefore, in this review, we will focus on: (1) Highlighting the fundamental role of the crosstalk among the three filamentous subsystems and (2) investigating pivotal cytoskeleton-associated proteins.
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Affiliation(s)
- Alessio Malacrida
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
| | - Cristina Meregalli
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
| | - Virginia Rodriguez-Menendez
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
| | - Gabriella Nicolini
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
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20
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Chen C, Cao L, Yang Y, Porter KJ, Osteryoung KW. ARC3 Activation by PARC6 Promotes FtsZ-Ring Remodeling at the Chloroplast Division Site. THE PLANT CELL 2019; 31:862-885. [PMID: 30824505 PMCID: PMC6501610 DOI: 10.1105/tpc.18.00948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/04/2019] [Accepted: 02/28/2019] [Indexed: 05/29/2023]
Abstract
Chloroplast division is initiated by assembly of the stromal Z ring, composed of cytoskeletal Filamenting temperature-sensitive Z (FtsZ) proteins. Midplastid Z-ring positioning is governed by the chloroplast Min (Minicell) system, which inhibits Z-ring assembly everywhere except the division site. The central Min-system player is the FtsZ-assembly inhibitor ACCUMULATION AND REPLICATION OF CHLOROPLASTS3 (ARC3). Here, we report Arabidopsis (Arabidopsis thaliana) chloroplasts contain two pools of ARC3: one distributed throughout the stroma, which presumably fully inhibits Z-ring assembly at nondivision sites, and the other localized to a midplastid ring-like structure. We show that ARC3 is recruited to the middle of the plastid by the inner envelope membrane protein PARALOG OF ARC6 (PARC6). ARC3 bears a C-terminal Membrane Occupation and Recognition Nexus (MORN) domain; previous yeast two-hybrid experiments with full-length and MORN-truncated ARC3 showed the MORN domain mediates ARC3-PARC6 interaction but prevents ARC3-FtsZ interaction. Using yeast three-hybrid experiments, we demonstrate that the MORN-dependent ARC3-PARC6 interaction enables full-length ARC3 to bind FtsZ. The resulting PARC6/ARC3/FtsZ complex enhances the dynamics of Z rings reconstituted in a heterologous system. Our findings lead to a model whereby activation of midplastid-localized ARC3 by PARC6 facilitates Z-ring remodeling during chloroplast division by promoting Z-ring dynamics and reveal a novel function for MORN domains in regulating protein-protein interactions.
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21
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Drosophila as a Model to Study Brain Innate Immunity in Health and Disease. Int J Mol Sci 2018; 19:ijms19123922. [PMID: 30544507 PMCID: PMC6321579 DOI: 10.3390/ijms19123922] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/05/2018] [Accepted: 12/05/2018] [Indexed: 12/21/2022] Open
Abstract
Innate immunity is the first line of defense against invading pathogens and plays an essential role in defending the brain against infection, injury, and disease. It is currently well recognized that central nervous system (CNS) infections can result in long-lasting neurological sequelae and that innate immune and inflammatory reactions are highly implicated in the pathogenesis of neurodegeneration. Due to the conservation of the mechanisms that govern neural development and innate immune activation from flies to mammals, the lack of a classical adaptive immune system and the availability of numerous genetic and genomic tools, the fruit fly Drosophila melanogaster presents opportunities to investigate the cellular and molecular mechanisms associated with immune function in brain tissue and how they relate to infection, injury and neurodegenerative diseases. Here, we present an overview of currently identified innate immune mechanisms specific to the adult Drosophila brain.
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22
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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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23
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Brazill JM, Cruz B, Zhu Y, Zhai RG. Nmnat mitigates sensory dysfunction in a Drosophila model of paclitaxel-induced peripheral neuropathy. Dis Model Mech 2018; 11:dmm.032938. [PMID: 29716954 PMCID: PMC6031360 DOI: 10.1242/dmm.032938] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/25/2018] [Indexed: 01/03/2023] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is the major dose-limiting side effect of many commonly used chemotherapeutic agents, including paclitaxel. Currently, there are no neuroprotective or effective symptomatic treatments for CIPN. Lack of understanding of the in vivo mechanisms of CIPN has greatly impeded the identification of therapeutic targets. Here, we optimized a model of paclitaxel-induced peripheral neuropathy using Drosophila larvae that recapitulates aspects of chemotherapy-induced sensory dysfunction. We showed that nociceptive sensitivity is associated with disrupted organization of microtubule-associated MAP1B/Futsch and aberrant stabilization of peripheral sensory dendrites. These findings establish a robust and amenable model for studying peripheral mechanisms of CIPN. Using this model, we uncovered a critical role for nicotinamide mononucleotide adenylyltransferase (Nmnat) in maintaining the integrity and function of peripheral sensory neurons and uncovered Nmnat's therapeutic potential against diverse sensory symptoms of CIPN. Summary: Neurotoxic side effects of chemotherapy are poorly understood. Here, the authors optimize a Drosophila model of paclitaxel-induced sensory dysfunction, which is then used to explore the neuroprotective capacity of Nmnat.
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Affiliation(s)
- Jennifer M Brazill
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Beverley Cruz
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yi Zhu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - R Grace Zhai
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA .,School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, Shandong 264005, China
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24
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Dung VM, Suong DNA, Okamaoto Y, Hiramatsu Y, Thao DTP, Yoshida H, Takashima H, Yamaguchi M. Neuron-specific knockdown of Drosophila PDHB induces reduction of lifespan, deficient locomotive ability, abnormal morphology of motor neuron terminals and photoreceptor axon targeting. Exp Cell Res 2018; 366:92-102. [PMID: 29501567 DOI: 10.1016/j.yexcr.2018.02.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/24/2018] [Accepted: 02/27/2018] [Indexed: 02/03/2023]
Abstract
Pyruvate dehydrogenase complex deficiency (PDCD) is a common primary cause of defects in mitochondrial function and also can lead to peripheral neuropathy. Pyruvate dehydrogenase E1 component subunit beta (PDHB) is a subunit of pyruvate dehydrogenase E1, which is a well-known component of PDC. In Drosophila melanogaster, the CG11876 (dPDHB) gene is a homolog of human PDHB. In this study, we established a Drosophila model with neuron-specific knockdown of dPDHB to investigate its role in neuropathy pathogenesis. Knockdown of dPDHB in pan-neurons induced locomotor defects in both larval and adult stages, which were consistent with abnormal morphology of the motor neuron terminals at neuromuscular junctions and mitochondrial fragmentation in brains. Moreover, neuron-specific knockdown of dPDHB also shortened the lifespan of adult flies. In addition, flies with knockdown of dPDHB manifested a rough eye phenotype and aberrant photoreceptor axon targeting. These results with the Drosophila model suggest the involvement of PDHB in peripheral neuropathy.
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Affiliation(s)
- Vuu My Dung
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; Department of Molecular and Environmental Biotechnology, Faculty of Biology and Biotechnology, University of Science, Vietnam National University - Ho Chi Minh City, Ho Chi Minh City 700000, Vietnam
| | - Dang Ngoc Anh Suong
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yuji Okamaoto
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yu Hiramatsu
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Dang Thi Phuong Thao
- Department of Molecular and Environmental Biotechnology, Faculty of Biology and Biotechnology, University of Science, Vietnam National University - Ho Chi Minh City, Ho Chi Minh City 700000, Vietnam
| | - Hideki Yoshida
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Masamitsu Yamaguchi
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
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25
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Boiko N, Medrano G, Montano E, Jiang N, Williams CR, Madungwe NB, Bopassa JC, Kim CC, Parrish JZ, Hargreaves KM, Stockand JD, Eaton BA. TrpA1 activation in peripheral sensory neurons underlies the ionic basis of pain hypersensitivity in response to vinca alkaloids. PLoS One 2017; 12:e0186888. [PMID: 29084244 PMCID: PMC5662086 DOI: 10.1371/journal.pone.0186888] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 10/09/2017] [Indexed: 12/30/2022] Open
Abstract
Chemotherapy induced peripheral neuropathy (CIPN), a side effect of many anti-cancer drugs including the vinca alkaloids, is characterized by a severe pain syndrome that compromises treatment in many patients. Currently there are no effective treatments for this pain syndrome except for the reduction of anti-cancer drug dose. Existing data supports the model that the pain associated with CIPN is the result of anti-cancer drugs augmenting the function of the peripheral sensory nociceptors but the cellular mechanisms underlying the effects of anti-cancer drugs on sensory neuron function are not well described. Studies from animal models have suggested a number of disease etiologies including mitotoxicity, axonal degeneration, immune signaling, and reduced sensory innervations but these outcomes are the result of prolonged treatment paradigms and do not necessarily represent the early formative events associated with CIPN. Here we show that acute exposure to vinca alkaloids results in an immediate pain syndrome in both flies and mice. Furthermore, we demonstrate that exposure of isolated sensory neurons to vinca alkaloids results in the generation of an inward sodium current capable of depolarizing these neurons to threshold resulting in neuronal firing. These neuronal effects of vinca alkaloids require the transient receptor potential ankyrin-1 (TrpA1) channel, and the hypersensitization to painful stimuli in response to the acute exposure to vinca alkaloids is reduced in TrpA1 mutant flies and mice. These findings demonstrate the direct excitation of sensory neurons by CIPN-causing chemotherapy drugs, and identify TrpA1 as an important target during the pathogenesis of CIPN.
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Affiliation(s)
- Nina Boiko
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - Geraldo Medrano
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - Elizabeth Montano
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - Nan Jiang
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Claire R. Williams
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Ngonidzashe B. Madungwe
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - Jean C. Bopassa
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - Charles C. Kim
- Verily, South San Francisco, California, United States of America
| | - Jay Z. Parrish
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Kenneth M. Hargreaves
- Department of Endodontics, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - James D. Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
| | - Benjamin A. Eaton
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, United States of America
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26
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Fukuda Y, Li Y, Segal RA. A Mechanistic Understanding of Axon Degeneration in Chemotherapy-Induced Peripheral Neuropathy. Front Neurosci 2017; 11:481. [PMID: 28912674 PMCID: PMC5583221 DOI: 10.3389/fnins.2017.00481] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/14/2017] [Indexed: 12/12/2022] Open
Abstract
Chemotherapeutic agents cause many short and long term toxic side effects to peripheral nervous system (PNS) that drastically alter quality of life. Chemotherapy-induced peripheral neuropathy (CIPN) is a common and enduring disorder caused by several anti-neoplastic agents. CIPN typically presents with neuropathic pain, numbness of distal extremities, and/or oversensitivity to thermal or mechanical stimuli. This adverse side effect often requires a reduction in chemotherapy dosage or even discontinuation of treatment. Currently there are no effective treatment options for CIPN. While the underlying mechanisms for CIPN are not understood, current data identify a “dying back” axon degeneration of distal nerve endings as the major pathology in this disorder. Therefore, mechanistic understanding of axon degeneration will provide insights into the pathway and molecular players responsible for CIPN. Here, we review recent findings that expand our understanding of the pathogenesis of CIPN and discuss pathways that may be shared with the axonal degeneration that occurs during developmental axon pruning and during injury-induced Wallerian degeneration. These mechanistic insights provide new avenues for development of therapies to prevent or treat CIPN.
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Affiliation(s)
- Yusuke Fukuda
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
| | - Yihang Li
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
| | - Rosalind A Segal
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
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TMEM184b Promotes Axon Degeneration and Neuromuscular Junction Maintenance. J Neurosci 2017; 36:4681-9. [PMID: 27122027 DOI: 10.1523/jneurosci.2893-15.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 03/07/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Complex nervous systems achieve proper connectivity during development and must maintain these connections throughout life. The processes of axon and synaptic maintenance and axon degeneration after injury are jointly controlled by a number of proteins within neurons, including ubiquitin ligases and mitogen activated protein kinases. However, our understanding of these molecular cascades is incomplete. Here we describe the phenotype resulting from mutation of TMEM184b, a protein identified in a screen for axon degeneration mediators. TMEM184b is highly expressed in the mouse nervous system and is found in recycling endosomes in neuronal cell bodies and axons. Disruption of TMEM184b expression results in prolonged maintenance of peripheral axons following nerve injury, demonstrating a role for TMEM184b in axon degeneration. In contrast to this protective phenotype in axons, uninjured mutant mice have anatomical and functional impairments in the peripheral nervous system. Loss of TMEM184b causes swellings at neuromuscular junctions that become more numerous with age, demonstrating that TMEM184b is critical for the maintenance of synaptic architecture. These swellings contain abnormal multivesicular structures similar to those seen in patients with neurodegenerative disorders. Mutant animals also show abnormal sensory terminal morphology. TMEM184b mutant animals are deficient on the inverted screen test, illustrating a role for TMEM184b in sensory-motor function. Overall, we have identified an important function for TMEM184b in peripheral nerve terminal structure, function, and the axon degeneration pathway. SIGNIFICANCE STATEMENT Our work has identified both neuroprotective and neurodegenerative roles for a previously undescribed protein, TMEM184b. TMEM184b mutation causes delayed axon degeneration following peripheral nerve injury, indicating that it participates in the degeneration process. Simultaneously, TMEM184b mutation causes progressive structural abnormalities at neuromuscular synapses and swellings within sensory terminals, and animals with this mutation display profound weakness. Thus, TMEM184b is necessary for normal peripheral nerve terminal morphology and maintenance. Loss of TMEM184b results in accumulation of autophagosomal structures in vivo, fitting with emerging studies that have linked autophagy disruption and neurological disease. Our work recognizes TMEM184b as a new player in the maintenance of the nervous system.
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Molecular pathogenesis of peripheral neuropathies: insights from Drosophila models. Curr Opin Genet Dev 2017; 44:61-73. [PMID: 28213160 DOI: 10.1016/j.gde.2017.01.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/10/2017] [Accepted: 01/26/2017] [Indexed: 01/18/2023]
Abstract
Peripheral neuropathies are characterized by degeneration of peripheral motor, sensory and/or autonomic axons, leading to progressive distal muscle weakness, sensory deficits and/or autonomic dysfunction. Acquired peripheral neuropathies, e.g., as a side effect of chemotherapy, are distinguished from inherited peripheral neuropathies (IPNs). Drosophila models for chemotherapy-induced peripheral neuropathy and several IPNs have provided novel insight into the molecular mechanisms underlying axonal degeneration. Forward genetic screens have predictive value for discovery of human IPN genes, and the pathogenicity of novel mutations in known IPN genes can be evaluated in Drosophila. Future screens for genes and compounds that modify Drosophila IPN phenotypes promise to make valuable contributions to unraveling the molecular pathogenesis and identification of therapeutic targets for these incurable diseases.
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Brace EJ, DiAntonio A. Models of axon regeneration in Drosophila. Exp Neurol 2017; 287:310-317. [PMID: 26996133 PMCID: PMC5026866 DOI: 10.1016/j.expneurol.2016.03.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 12/14/2022]
Abstract
Maintaining neuronal connectivity in the face of injury and disease is a major challenge for the nervous system. The great length of axons makes them particularly vulnerable to insult with dire consequences for neuronal function. In the peripheral nervous system there is a program of axonal regeneration that can reestablish connectivity. In the mammalian central nervous system, however, injured axons have little or no capacity to regenerate. The molecular mechanisms that promote axon regeneration have begun to be identified and many of the implicated pathways are evolutionarily conserved. Here we discuss Drosophila models of axonal regrowth, describe insights derived from these studies, and highlight future directions in the use of the fly for dissecting the mechanisms of axonal regeneration.
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Affiliation(s)
- E J Brace
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA, 63110
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA, 63110.
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Gornstein EL, Schwarz TL. Neurotoxic mechanisms of paclitaxel are local to the distal axon and independent of transport defects. Exp Neurol 2016; 288:153-166. [PMID: 27894788 DOI: 10.1016/j.expneurol.2016.11.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 11/15/2022]
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting side effect of paclitaxel and other chemotherapeutic agents. Paclitaxel binds and stabilizes microtubules, but the cellular mechanisms that underlie paclitaxel's neurotoxic effects are not well understood. We therefore used primary cultures of adult murine dorsal root ganglion neurons, the cell type affected in patients, to examine leading hypotheses to explain paclitaxel neurotoxicity. We address the role of microtubule hyperstabilization and its downstream effects. Paclitaxel administered at 10-50nM for 1-3days induced retraction bulbs at the tips of axons and arrested axon growth without triggering axon fragmentation or cell death. By correlating the toxic effects and microtubule stabilizing activity of structurally different microtubule stabilizing compounds, we confirmed that microtubule hyperstabilization, rather than an off-target effect, is the likely primary cause of paclitaxel neurotoxicity. We examined potential downstream consequences of microtubule hyperstabilization and found that changes in levels of tubulin posttranslational modifications, although present after paclitaxel exposure, are not implicated in the paclitaxel neurotoxicity we observed in the cultures. Additionally, defects in axonal transport were not implicated as an early, causative mechanism of paclitaxel's toxic effects on dorsal root ganglion neurons. By using microfluidic chambers to selectively treat different parts of the axon with paclitaxel, we found that the distal axon was primarily vulnerable to paclitaxel, indicating that paclitaxel acts directly on the distal axon to induce degenerative effects. Together, our findings point to local effects of microtubule hyperstabilization on the distal-most portion of the axon as an early mediator of paclitaxel neurotoxicity. Because sensory neurons have a unique and ongoing requirement for distal growth in order to reinnervate the epidermis as it turns over, we propose that the ability of paclitaxel to arrest their growth accounts for the selective vulnerability of sensory neurons to paclitaxel neurotoxicity.
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Affiliation(s)
- Erica L Gornstein
- The F.M. Kirby Neurobiology Center, Children's Hospital Boston, Boston, MA 02115, USA; Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115, USA
| | - Thomas L Schwarz
- The F.M. Kirby Neurobiology Center, Children's Hospital Boston, Boston, MA 02115, USA.
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Bramley JC, Collins SVA, Clark KB, Buchser WJ. Avian axons undergo Wallerian degeneration after injury and stress. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 202:813-822. [PMID: 27614771 DOI: 10.1007/s00359-016-1123-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 06/20/2016] [Accepted: 08/31/2016] [Indexed: 12/22/2022]
Abstract
The integrity of long axons is essential for neural communication. Unfortunately, relatively minor stress to a neuron can cause extensive loss of this integrity. Axon degeneration is the cell-intrinsic program that actively deconstructs an axon after injury or damage. Although ultrastructural examination has revealed signs of axon degeneration in vivo, the occurrence and progression of axon degeneration in avian species have not yet been documented in vitro. Here, we use a novel cell culture system with primary embryonic zebra finch retinal ganglion cells to interrogate the properties of avian axon degeneration. First, we establish that both axotomy and a chemically induced injury (taxol and vincristine) are sufficient to initiate degeneration. These events are dependent on a late influx of calcium. In addition, as in mammals, the NAD pathway is involved, since a decrease in NMN with FK866 can reduce degeneration. Importantly, these retinal ganglion cell axons were sensitive to a pressure-induced injury, which may mimic the effect of high intraocular pressure associated with glaucoma. We have demonstrated that avian neurons undergo Wallerian degeneration in response to both physical and chemical injury. Subsequent avian studies will investigate whether blocking the degeneration pathway can protect individuals from neurodegenerative disease.
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Affiliation(s)
- John C Bramley
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA
| | - Samantha V A Collins
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA
| | - Karen B Clark
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA
| | - William J Buchser
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA.
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32
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Cela P, Hampl M, Fu KK, Kunova Bosakova M, Krejci P, Richman JM, Buchtova M. MORN5 Expression during Craniofacial Development and Its Interaction with the BMP and TGFβ Pathways. Front Physiol 2016; 7:378. [PMID: 27630576 PMCID: PMC5005375 DOI: 10.3389/fphys.2016.00378] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 08/17/2016] [Indexed: 12/23/2022] Open
Abstract
MORN5 (MORN repeat containing 5) is encoded by a locus positioned on chromosome 17 in the chicken genome. The MORN motif is found in multiple copies in several proteins including junctophilins or phosphatidylinositol phosphate kinase family and the MORN proteins themselves are found across the animal and plant kingdoms. MORN5 protein has a characteristic punctate pattern in the cytoplasm in immunofluorescence imaging. Previously, MORN5 was found among differentially expressed genes in a microarray profiling experiment of the chicken embryo head. Here, we provided in situ hybridization to analyse, in detail, the MORN5 expression in chick craniofacial structures. The expression of MORN5 was first observed at stage HH17-18 (E2.5). MORN5 expression gradually appeared on either side of the primitive oral cavity, within the maxillary region. At stage HH20 (E3), prominent expression was localized in the mandibular prominences lateral to the midline. From stage HH20 up to HH29 (E6), there was strong expression in restricted regions of the maxillary and mandibular prominences. The frontonasal mass (in the midline of the face) expressed MORN5, starting at HH27 (E5). The expression was concentrated in the corners or globular processes, which will ultimately fuse with the cranial edges of the maxillary prominences. MORN5 expression was maintained in the fusion zone up to stage HH29. In sections MORN5 expression was localized preferentially in the mesenchyme. Previously, we examined signals that regulate MORN5 expression in the face based on a previous microarray study. Here, we validated the array results with in situ hybridization and QPCR. MORN5 was downregulated 24 h after Noggin and/or RA treatment. We also determined that BMP pathway genes are downstream of MORN5 following siRNA knockdown. Based on these results, we conclude that MORN5 is both regulated by and required for BMP signaling. The restricted expression of MORN5 in the lip fusion zone shown here supports the human genetic data in which MORN5 variants were associated with increased risk of non-syndromic cleft lip with or without cleft palate.
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Affiliation(s)
- Petra Cela
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech RepublicBrno, Czech Republic; Department of Animal Physiology and Immunology, Institute of Experimental Biology, Masaryk UniversityBrno, Czech Republic
| | - Marek Hampl
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech RepublicBrno, Czech Republic; Department of Animal Physiology and Immunology, Institute of Experimental Biology, Masaryk UniversityBrno, Czech Republic
| | - Katherine K Fu
- Life Sciences Institute, University of British Columbia Vancouver, BC, Canada
| | | | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk UniversityBrno, Czech Republic; International Clinical Research Center, St. Anne's University HospitalBrno, Czech Republic
| | - Joy M Richman
- Life Sciences Institute, University of British Columbia Vancouver, BC, Canada
| | - Marcela Buchtova
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech RepublicBrno, Czech Republic; Department of Animal Physiology and Immunology, Institute of Experimental Biology, Masaryk UniversityBrno, Czech Republic
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Tao J, Feng C, Rolls MM. The microtubule-severing protein fidgetin acts after dendrite injury to promote their degeneration. J Cell Sci 2016; 129:3274-81. [PMID: 27411367 DOI: 10.1242/jcs.188540] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/08/2016] [Indexed: 02/01/2023] Open
Abstract
After being severed from the cell body, axons initiate an active degeneration program known as Wallerian degeneration. Although dendrites also seem to have an active injury-induced degeneration program, no endogenous regulators of this process are known. Because microtubule disassembly has been proposed to play a role in both pruning and injury-induced degeneration, we used a Drosophila model to identify microtubule regulators involved in dendrite degeneration. We found that, when levels of fidgetin were reduced using mutant or RNA interference (RNAi) strategies, dendrite degeneration was delayed, but axon degeneration and dendrite pruning proceeded with normal timing. We explored two possible ways in which fidgetin could promote dendrite degeneration: (1) by acting constitutively to moderate microtubule stability in dendrites, or (2) by acting specifically after injury to disassemble microtubules. When comparing microtubule dynamics and stability in uninjured neurons with and without fidgetin, we could not find evidence that fidgetin regulated microtubule stability constitutively. However, we identified a fidgetin-dependent increase in microtubule dynamics in severed dendrites. We conclude that fidgetin acts after injury to promote disassembly of microtubules in dendrites severed from the cell body.
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Affiliation(s)
- Juan Tao
- Department of Biochemistry and Molecular Biology and The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Chengye Feng
- Department of Biochemistry and Molecular Biology and The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Melissa M Rolls
- Department of Biochemistry and Molecular Biology and The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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Zhang L, Shang XJ, Li HF, Shi YQ, Li W, Teves ME, Wang ZQ, Jiang GF, Song SZ, Zhang ZB. Characterization of membrane occupation and recognition nexus repeat containing 3, meiosis expressed gene 1 binding partner, in mouse male germ cells. Asian J Androl 2016; 17:86-93. [PMID: 25248657 PMCID: PMC4291884 DOI: 10.4103/1008-682x.138186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Mammalian spermatogenesis is a well-organized process of cell development and differentiation. Meiosis expressed gene 1 (MEIG1) plays an essential role in the regulation of spermiogenesis. To explore potential mechanisms of MEIG1's action, a yeast two-hybrid screen was conducted, and several potential binding partners were identified; one of them was membrane occupation and recognition nexus repeat containing 3 (MORN3). MORN3 mRNA is only abundant in mouse testis. In the testis, Morn3 mRNA is highly expressed in the spermiogenesis stage. Specific anti-MORN3 polyclonal antibody was generated against N-terminus of the full-length MORN3 protein, and MORN3 expression and localization was examined in vitro and in vivo. In transfected Chinese hamster ovary cells, the antibody specifically crossed-reacted the full-length MORN3 protein, and immunofluorescence staining revealed that MORN3 was localized throughout the cytoplasm. Among multiple mouse tissues, about 25 kDa protein, was identified only in the testis. The protein was highly expressed after day 20 of birth. Immunofluorescence staining on mixed testicular cells isolated from adult wild-type mice demonstrated that MORN3 was expressed in the acrosome in germ cells throughout spermiogenesis. The protein was also present in the manchette of elongating spermatids. The total MORN3 expression and acrosome localization were not changed in the Meig 1-deficient mice. However, its expression in manchette was dramatically reduced in the mutant mice. Our studies suggest that MORN3 is another regulator for spermatogenesis, probably together with MEIG1.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Zhi-Bing Zhang
- Department of Preventive Medicine, School of Public Health, Wuhan University of Science and Technology, Wuhan, China; Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, VA, USA, China
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Nicotinamide mononucleotide adenylyltransferase promotes hypoxic survival by activating the mitochondrial unfolded protein response. Cell Death Dis 2016; 7:e2113. [PMID: 26913604 PMCID: PMC4849163 DOI: 10.1038/cddis.2016.5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/18/2015] [Accepted: 12/27/2015] [Indexed: 02/04/2023]
Abstract
Gain-of-function mutations in the mouse nicotinamide mononucleotide adenylyltransferase type 1 (Nmnat1) produce two remarkable phenotypes: protection against traumatic axonal degeneration and reduced hypoxic brain injury. Despite intensive efforts, the mechanism of Nmnat1 cytoprotection remains elusive. To develop a new model to define this mechanism, we heterologously expressed a mouse Nmnat1 non-nuclear-localized gain-of-function mutant gene (m-nonN-Nmnat1) in the nematode Caenorhabditis elegans and show that it provides protection from both hypoxia-induced animal death and taxol-induced axonal pathology. Additionally, we find that m-nonN-Nmnat1 significantly lengthens C. elegans lifespan. Using the hypoxia-protective phenotype in C. elegans, we performed a candidate screen for genetic suppressors of m-nonN-Nmnat1 cytoprotection. Loss of function in two genes, haf-1 and dve-1, encoding mitochondrial unfolded protein response (mitoUPR) factors were identified as suppressors. M-nonN-Nmnat1 induced a transcriptional reporter of the mitoUPR gene hsp-6 and provided protection from the mitochondrial proteostasis toxin ethidium bromide. M-nonN-Nmnat1 was also protective against axonal degeneration in C. elegans induced by the chemotherapy drug taxol. Taxol markedly reduced basal expression of a mitoUPR reporter; the expression was restored by m-nonN-Nmnat1. Taken together, these data implicate the mitoUPR as a mechanism whereby Nmnat1 protects from hypoxic and axonal injury.
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Gerdts J, Summers DW, Milbrandt J, DiAntonio A. Axon Self-Destruction: New Links among SARM1, MAPKs, and NAD+ Metabolism. Neuron 2016; 89:449-60. [PMID: 26844829 PMCID: PMC4742785 DOI: 10.1016/j.neuron.2015.12.023] [Citation(s) in RCA: 245] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Wallerian axon degeneration is a form of programmed subcellular death that promotes axon breakdown in disease and injury. Active degeneration requires SARM1 and MAP kinases, including DLK, while the NAD+ synthetic enzyme NMNAT2 prevents degeneration. New studies reveal that these pathways cooperate in a locally mediated axon destruction program, with NAD+ metabolism playing a central role. Here, we review the biology of Wallerian-type axon degeneration and discuss the most recent findings, with special emphasis on critical signaling events and their potential as therapeutic targets for axonopathy.
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Affiliation(s)
- Josiah Gerdts
- Department of Genetics, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA
| | - Daniel W Summers
- Department of Genetics, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA.
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Sasaki Y, Margolin Z, Borgo B, Havranek JJ, Milbrandt J. Characterization of Leber Congenital Amaurosis-associated NMNAT1 Mutants. J Biol Chem 2015; 290:17228-38. [PMID: 26018082 DOI: 10.1074/jbc.m115.637850] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Indexed: 01/27/2023] Open
Abstract
Leber congenital amaurosis 9 (LCA9) is an autosomal recessive retinal degeneration condition caused by mutations in the NAD(+) biosynthetic enzyme NMNAT1. This condition leads to early blindness but no other consistent deficits have been reported in patients with NMNAT1 mutations despite its central role in metabolism and ubiquitous expression. To study how these mutations affect NMNAT1 function and ultimately lead to the retinal degeneration phenotype, we performed detailed analysis of LCA-associated NMNAT1 mutants, including the expression, nuclear localization, enzymatic activity, secondary structure, oligomerization, and promotion of axonal and cellular integrity in response to injury. In many assays, most mutants produced results similar to wild type NMNAT1. Indeed, NAD(+) synthetic activity is unlikely to be a primary mechanism underlying retinal degeneration as most LCA-associated NMNAT1 mutants had normal enzymatic activity. In contrast, the secondary structure of many NMNAT1 mutants was relatively less stable as they lost enzymatic activity after heat shock, whereas wild type NMNAT1 retains significant activity after this stress. These results suggest that LCA-associated NMNAT1 mutants are more vulnerable to stressful conditions that lead to protein unfolding, a potential contributor to the retinal degeneration observed in this syndrome.
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Affiliation(s)
- Yo Sasaki
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Zachary Margolin
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Benjamin Borgo
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - James J Havranek
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jeffrey Milbrandt
- From the Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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Habicht J, Woehle C, Gould SB. Tetrahymena Expresses More than a Hundred Proteins with Lipid-binding MORN Motifs that can Differ in their Subcellular Localisations. J Eukaryot Microbiol 2015; 62:694-700. [PMID: 25847055 DOI: 10.1111/jeu.12216] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/20/2015] [Indexed: 12/11/2022]
Abstract
Proteins with membrane occupation and recognition nexus (MORN) motifs are associated with cell fission in apicomplexan parasites, chloroplast division in Arabidopsis and the motility of sperm cells. We found that ciliates are among those that encode the largest variety of MORN proteins. Tetrahymena thermophila expresses 129 MORN protein-encoding genes, some of which are specifically up-regulated during conjugation. A lipid-binding assay underpins the assumption that the predominant function of MORN motifs themselves is to confer the ability of lipid binding. The localisation of four MORN candidate proteins with similar characteristics highlights the functional diversity of this group especially in ciliates.
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Affiliation(s)
- Jörn Habicht
- Institute for Molecular Evolution, Heinrich-Heine-University, 40225, Düsseldorf, Germany
| | - Christian Woehle
- Institute for Microbiology, Christian-Albrecht-University, 24118, Kiel, Germany
| | - Sven B Gould
- Institute for Molecular Evolution, Heinrich-Heine-University, 40225, Düsseldorf, Germany
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Identification of 12/15-lipoxygenase as a regulator of axon degeneration through high-content screening. J Neurosci 2015; 35:2927-41. [PMID: 25698732 DOI: 10.1523/jneurosci.2936-14.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Axon degeneration is a programed process that takes place during development, in response to neuronal injury, and as a component of neurodegenerative disease pathology, yet the molecular mechanisms that drive this process remain poorly defined. In this study, we have developed a semi-automated, 384-well format axon degeneration assay in rat dorsal root ganglion (DRG) neurons using a trophic factor withdrawal paradigm. Using this setup, we have screened a library of known drugs and bioactives to identify several previously unappreciated regulators of axon degeneration, including lipoxygenases. Multiple structurally distinct lipoxygenase inhibitors as well as mouse DRG neurons lacking expression of 12/15-lipoxygenase display protection of axons in this context. Retinal ganglion cell axons from 12/15-lipoxygenase-null mice were similarly protected from degeneration following nerve crush injury. Through additional mechanistic studies, we demonstrate that lipoxygenases act cell autonomously within neurons to regulate degeneration, and are required for mitochondrial permeabilization and caspase activation in the axon. These findings suggest that these enzymes may represent an attractive target for treatment of neuropathies and provide a potential mechanism for the neuroprotection observed in various settings following lipoxygenase inhibitor treatment.
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Abstract
Neurite degeneration is a hallmark feature of nearly all neurodegenerative diseases, occurs after most brain trauma, and is thought to be the underlying cause of functional loss in patients. Understanding the genetic basis of neurite degeneration represents a major challenge in the neuroscience field. If it is possible to define key signaling pathways that promote neurite destruction, their blockade represents an exciting new potential therapeutic approach to suppressing neurological loss in patients. This review highlights recently developed models that can be used to study fundamental aspects of neuronal injury using the fruit fly Drosophila. The speed, precision, and powerful molecular-genetic tools available in the fruit fly make for an attractive system in which to dissect neuronal signaling after injury. Their use has led to the identification of some of the first molecules whose endogenous function includes promoting axonal degeneration after axotomy, and these signaling pathways appear functionally well conserved in mammals.
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A rise in NAD precursor nicotinamide mononucleotide (NMN) after injury promotes axon degeneration. Cell Death Differ 2014; 22:731-42. [PMID: 25323584 PMCID: PMC4392071 DOI: 10.1038/cdd.2014.164] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/30/2014] [Accepted: 08/29/2014] [Indexed: 12/20/2022] Open
Abstract
NAD metabolism regulates diverse biological processes, including ageing, circadian rhythm and axon survival. Axons depend on the activity of the central enzyme in NAD biosynthesis, nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2), for their maintenance and degenerate rapidly when this activity is lost. However, whether axon survival is regulated by the supply of NAD or by another action of this enzyme remains unclear. Here we show that the nucleotide precursor of NAD, nicotinamide mononucleotide (NMN), accumulates after nerve injury and promotes axon degeneration. Inhibitors of NMN-synthesising enzyme NAMPT confer robust morphological and functional protection of injured axons and synapses despite lowering NAD. Exogenous NMN abolishes this protection, suggesting that NMN accumulation within axons after NMNAT2 degradation could promote degeneration. Ectopic expression of NMN deamidase, a bacterial NMN-scavenging enzyme, prolongs survival of injured axons, providing genetic evidence to support such a mechanism. NMN rises prior to degeneration and both the NAMPT inhibitor FK866 and the axon protective protein WldS prevent this rise. These data indicate that the mechanism by which NMNAT and the related WldS protein promote axon survival is by limiting NMN accumulation. They indicate a novel physiological function for NMN in mammals and reveal an unexpected link between new strategies for cancer chemotherapy and the treatment of axonopathies.
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Pope HM, Voigt MM. Peripheral glia have a pivotal role in the initial response to axon degeneration of peripheral sensory neurons in zebrafish. PLoS One 2014; 9:e103283. [PMID: 25058656 PMCID: PMC4109997 DOI: 10.1371/journal.pone.0103283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 06/30/2014] [Indexed: 02/07/2023] Open
Abstract
Axon degeneration is a feature of many peripheral neuropathies. Understanding the organismal response to this degeneration may aid in identifying new therapeutic targets for treatment. Using a transgenic zebrafish line expressing a bacterial nitroreductase (Ntr)/mCherry fusion protein in the peripheral sensory neurons of the V, VII, IX, and X cranial nerves, we were able to induce and visualize the pathology of axon degeneration in vivo. Exposure of 4 days post fertilization Ntr larvae to the prodrug metronidazole (Met), which Ntr metabolizes into cytotoxic metabolites, resulted in dose-dependent cell death and axon degeneration. This was limited to the Ntr-expressing sensory neurons, as neighboring glia and motor axons were unaffected. Cell death was rapid, becoming apparent 3-4 hours after Met treatment, and was followed by phagocytosis of soma and axon debris by cells within the nerves and ganglia beginning at 4-5 hours of exposure. Although neutrophils appear to be activated in response to the degenerating neurons, they did not accumulate at the sites of degeneration. In contrast, macrophages were found to be attracted to the sites of the degenerating axons, where they phagocytosed debris. We demonstrated that peripheral glia are critical for both the phagocytosis and inflammatory response to degenerating neurons: mutants that lack all peripheral glia (foxD3-/-; Ntr) exhibit a much reduced reaction to axonal degeneration, resulting in a dramatic decrease in the clearance of debris, and impaired macrophage recruitment. Overall, these results show that this zebrafish model of peripheral sensory axon degeneration exhibits many aspects common to peripheral neuropathies and that peripheral glia play an important role in the initial response to this process.
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Affiliation(s)
- Holly M. Pope
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
| | - Mark M. Voigt
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
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Freeman MR. Signaling mechanisms regulating Wallerian degeneration. Curr Opin Neurobiol 2014; 27:224-31. [PMID: 24907513 DOI: 10.1016/j.conb.2014.05.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 05/01/2014] [Accepted: 05/02/2014] [Indexed: 02/06/2023]
Abstract
Wallerian degeneration (WD) occurs after an axon is cut or crushed and entails the disintegration and clearance of the severed axon distal to the injury site. WD was initially thought to result from the passive wasting away of the distal axonal fragment, presumably because it lacked a nutrient supply from the cell body. The discovery of the slow Wallerian degeneration (Wld(s)) mutant mouse, in which distal severed axons survive intact for weeks rather than only one to two days, radically changed our thoughts on the autonomy of axon survival. Wld(s) taught us that under some conditions the axonal compartment can survive for weeks after axotomy without a cell body. The phenotypic and molecular characterization of Wld(S) and current models for Wld(S) molecular function are reviewed herein-the mechanism(s) by which Wld(S) spares severed axons remains unresolved. However, recent studies inspired by Wld(s) have led to the identification of the first 'axon death' signaling molecules whose endogenous activities promote axon destruction during WD.
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Affiliation(s)
- Marc R Freeman
- Dept of Neurobiology, Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, MA 01605-2324, United States.
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Wallerian degeneration: an emerging axon death pathway linking injury and disease. Nat Rev Neurosci 2014; 15:394-409. [DOI: 10.1038/nrn3680] [Citation(s) in RCA: 387] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Toxic and drug-induced peripheral neuropathies: updates on causes, mechanisms and management. Curr Opin Neurol 2014; 26:481-8. [PMID: 23995278 DOI: 10.1097/wco.0b013e328364eb07] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review discusses publications highlighting current research on toxic, chemotherapy-induced peripheral neuropathies (CIPNs), and drug-induced peripheral neuropathies (DIPNs). RECENT FINDINGS The emphasis in clinical studies is on the early detection and grading of peripheral neuropathies, whereas recent studies in animal models have given insights into molecular mechanisms, with the discovery of novel neuronal, axonal, and Schwann cell targets. Some substances trigger inflammatory changes in the peripheral nerves. Pharmacogenetic techniques are underway to identify genes that may help to predict individuals at higher risk of developing DIPNs. Several papers have been published on chemoprotectants; however, to date, this approach has not been shown effective in clinical trials. SUMMARY Both length and nonlength-dependent neuropathies are encountered, including small-fiber involvement. The introduction of new diagnostic techniques, such as excitability studies, skin laser Doppler flowmetry, and pharmacogenetics, holds promise for early detection and to elucidate underlying mechanisms. New approaches to improve functions and quality of life in CIPN patients are discussed. Apart from developing less neurotoxic anticancer therapies, there is still hope to identify chemoprotective agents (erythropoietin and substances involved in the endocannabinoid system are promising) able to prevent or correct painful CIPNs.
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Gornstein E, Schwarz TL. The paradox of paclitaxel neurotoxicity: Mechanisms and unanswered questions. Neuropharmacology 2014; 76 Pt A:175-83. [DOI: 10.1016/j.neuropharm.2013.08.016] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/26/2013] [Accepted: 08/07/2013] [Indexed: 11/17/2022]
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Brabb T, Carbone L, Snyder J, Phillips N. Institutional animal care and use committee considerations for animal models of peripheral neuropathy. ILAR J 2014; 54:329-37. [PMID: 24615447 PMCID: PMC4383225 DOI: 10.1093/ilar/ilt045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Peripheral neuropathy and neuropathic pain are debilitating, life-altering conditions that affect a significant proportion of the human population. Animal models, used to study basic disease mechanisms and treatment modalities, are diverse and provide many challenges for institutional animal care and use committee (IACUC) review and postapproval monitoring. Items to consider include regulatory and ethical imperatives in animal models that may be designed to study pain, the basic mechanism of neurodegeneration, and different disease processes for which neuropathic pain is a side effect. Neuropathic pain can be difficult to detect or quantify in many models, and pain management is often unsuccessful in both humans and animals, inspiring the need for more research. Design of humane endpoints requires clear communication of potential adverse outcomes and solutions. Communication with the IACUC, researchers, and veterinary staff is also key for successful postapproval monitoring of these challenging models.
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Affiliation(s)
- Thea Brabb
- Address correspondence and reprint requests to Dr. Thea Brabb, Box 357190, University of Washington, Seattle, WA 98195 or email
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Beirowski B. Concepts for regulation of axon integrity by enwrapping glia. Front Cell Neurosci 2013; 7:256. [PMID: 24391540 PMCID: PMC3867696 DOI: 10.3389/fncel.2013.00256] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/25/2013] [Indexed: 12/16/2022] Open
Abstract
Long axons and their enwrapping glia (EG; Schwann cells (SCs) and oligodendrocytes (OLGs)) form a unique compound structure that serves as conduit for transport of electric and chemical information in the nervous system. The peculiar cytoarchitecture over an enormous length as well as its substantial energetic requirements make this conduit particularly susceptible to detrimental alterations. Degeneration of long axons independent of neuronal cell bodies is observed comparatively early in a range of neurodegenerative conditions as a consequence of abnormalities in SCs and OLGs . This leads to the most relevant disease symptoms and highlights the critical role that these glia have for axon integrity, but the underlying mechanisms remain elusive. The quest to understand why and how axons degenerate is now a crucial frontier in disease-oriented research. This challenge is most likely to lead to significant progress if the inextricable link between axons and their flanking glia in pathological situations is recognized. In this review I compile recent advances in our understanding of the molecular programs governing axon degeneration, and mechanisms of EG’s non-cell autonomous impact on axon-integrity. A particular focus is placed on emerging evidence suggesting that EG nurture long axons by virtue of their intimate association, release of trophic substances, and neurometabolic coupling. The correction of defects in these functions has the potential to stabilize axons in a variety of neuronal diseases in the peripheral nervous system and central nervous system (PNS and CNS).
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Affiliation(s)
- Bogdan Beirowski
- Department of Genetics, Washington University School of Medicine Saint Louis, MO, USA
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Abstract
Axon degeneration is an evolutionarily conserved pathway that eliminates damaged or unneeded axons. Manipulation of this poorly understood pathway may allow treatment of a wide range of neurological disorders. In an RNAi-based screen performed in cultured mouse DRG neurons, we observed strong suppression of injury-induced axon degeneration upon knockdown of Sarm1 [SARM (sterile α-motif-containing and armadillo-motif containing protein)]. We find that a SARM-dependent degeneration program is engaged by disparate neuronal insults: SARM ablation blocks axon degeneration induced by axotomy or vincristine treatment, while SARM acts in parallel with a soma-derived caspase-dependent pathway following trophic withdrawal. SARM is a multidomain protein that associates with neuronal mitochondria. Deletion of the N-terminal mitochondrial localization sequence disrupts SARM mitochondrial localization in neurons but does not alter its ability to promote axon degeneration. In contrast, mutation of either the SAM (sterile α motif) or TIR (Toll-interleukin-1 receptor) domains abolishes the ability of SARM to promote axonal degeneration, while a SARM mutant containing only these domains elicits axon degeneration and nonapoptotic neuronal death even in the absence of injury. Protein-protein interaction studies demonstrate that the SAM domains are necessary and sufficient to mediate SARM-SARM binding. SARM mutants lacking a TIR domain bind full-length SARM and exhibit strong dominant-negative activity. These results indicate that SARM plays an integral role in the dismantling of injured axons and support a model in which SAM-mediated multimerization is necessary for TIR-dependent engagement of a downstream destruction pathway. These findings suggest that inhibitors of SAM and TIR interactions represent therapeutic candidates for blocking pathological axon loss and neuronal cell death.
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Abstract
NMNAT2 is an NAD(+)-synthesizing enzyme with an essential axon maintenance role in primary culture neurons. We have generated an Nmnat2 gene trap mouse to examine the role of NMNAT2 in vivo. Homozygotes die perinatally with a severe peripheral nerve/axon defect and truncated axons in the optic nerve and other CNS regions. The cause appears to be limited axon extension, rather than dying-back degeneration of existing axons, which was previously proposed for the NMNAT2-deficient Blad mutant mouse. Neurite outgrowth in both PNS and CNS neuronal cultures consistently stalls at 1-2 mm, similar to the length of truncated axons in the embryos. Crucially, this suggests an essential role for NMNAT2 during axon growth. In addition, we show that the Wallerian degeneration slow protein (Wld(S)), a more stable, aberrant NMNAT that can substitute the axon maintenance function of NMNAT2 in primary cultures, can also correct developmental defects associated with NMNAT2 deficiency. This is dose-dependent, with extension of life span to at least 3 months by homozygous levels of Wld(S) the most obvious manifestation. Finally, we propose that endogenous mechanisms also compensate for otherwise limiting levels of NMNAT2. This could explain our finding that conditional silencing of a single Nmnat2 allele triggers substantial degeneration of established neurites, whereas similar, or greater, reduction of NMNAT2 in constitutively depleted neurons is compatible with normal axon growth and survival. A requirement for NMNAT2 for both axon growth and maintenance suggests that reduced levels could impair axon regeneration as well as axon survival in aging and disease.
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