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Zurek NA, Thiyagarajan S, Ehsanian R, Goins AE, Goyal S, Shilling M, Lambert CG, Westlund KN, Alles SRA. Machine Learning Elucidates Electrophysiological Properties Predictive of Multi- and Single-Firing Human and Mouse Dorsal Root Ganglia Neurons. eNeuro 2024; 11:ENEURO.0248-24.2024. [PMID: 39299808 PMCID: PMC11457269 DOI: 10.1523/eneuro.0248-24.2024] [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: 06/09/2024] [Revised: 08/08/2024] [Accepted: 09/13/2024] [Indexed: 09/22/2024] Open
Abstract
Human and mouse dorsal root ganglia (hDRG and mDRG) neurons are important tools in understanding the molecular and electrophysiological mechanisms that underlie nociception and drive pain behaviors. One of the simplest differences in firing phenotypes is that neurons are single-firing (exhibit only one action potential) or multi-firing (exhibit 2 or more action potentials). To determine if single- and multi-firing hDRG neurons exhibit differences in intrinsic properties, firing phenotypes, and AP waveform properties, and if these properties could be used to predict multi-firing, we measured 22 electrophysiological properties by whole-cell patch-clamp electrophysiology of 94 hDRG neurons from six male and four female donors. We then analyzed the data using several machine learning models to determine if these properties could be used to predict multi-firing. We used 1,000 iterations of Monte Carlo cross-validation to split the data into different train and test sets and tested the logistic regression, k-nearest neighbors, random forest, support vector classifier, and XGBoost machine learning models. All models tested had a >80% accuracy on average, with support vector classifier, and XGBoost performing the best. We found that several properties correlated with multi-firing hDRG neurons and together could be used to predict multi-firing neurons in hDRG including a long decay time, a low rheobase, and long first spike latency. We also found that the hDRG models were able to predict multi-firing with 90% accuracy in mDRG neurons. Understanding these properties could be beneficial in the elucidation of targets on peripheral sensory neurons related to pain.
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Affiliation(s)
- Nesia A Zurek
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Sherwin Thiyagarajan
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Reza Ehsanian
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Aleyah E Goins
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Sachin Goyal
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Mark Shilling
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Christophe G Lambert
- Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131
| | - Karin N Westlund
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
| | - Sascha R A Alles
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87106
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Wang X, Luo H, Peng X, Chen J. Spider and scorpion knottins targeting voltage-gated sodium ion channels in pain signaling. Biochem Pharmacol 2024; 227:116465. [PMID: 39102991 DOI: 10.1016/j.bcp.2024.116465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 07/30/2024] [Accepted: 08/02/2024] [Indexed: 08/07/2024]
Abstract
In sensory neurons that transmit pain signals, whether acute or chronic, voltage-gated sodium channels (VGSCs) are crucial for regulating excitability. NaV1.1, NaV1.3, NaV1.6, NaV1.7, NaV1.8, and NaV1.9 have been demonstrated and defined their functional roles in pain signaling based on their biophysical properties and distinct patterns of expression in each subtype of sensory neurons. Scorpions and spiders are traditional Chinese medicinal materials, belonging to the arachnid class. Most of the studied species of them have evolved venom peptides that exhibit a wide variety of knottins specifically targeting VGSCs with subtype selectivity and conformational specificity. This review provides an overview on the exquisite knottins from scorpion and spider venoms targeting pain-related NaV channels, describing the sequences and the structural features as well as molecular determinants that influence their selectivity on special subtype and at particular conformation, with an aim for the development of novel research tools on NaV channels and analgesics with minimal adverse effects.
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Affiliation(s)
- Xiting Wang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Huan Luo
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Xiaozhen Peng
- School of Public Health & Laboratory Medicine, Hunan University of Medicine, Huaihua 418000, China.
| | - Jinjun Chen
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China; Hunan Provincial Engineering Technology Research Center for Cell Mechanics and Function Analysis, Changsha 418000, China.
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Zurek NA, Thiyagarajan S, Ehsanian R, Goins AE, Goyal S, Shilling M, Lambert CG, Westlund KN, Alles SRA. Machine learning elucidates electrophysiological properties predictive of multi- and single-firing human and mouse dorsal root ganglia neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.03.597213. [PMID: 38895314 PMCID: PMC11185744 DOI: 10.1101/2024.06.03.597213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Human and mouse dorsal root ganglia (hDRG and mDRG) neurons are important tools in understanding the molecular and electrophysiological mechanisms that underlie nociception and drive pain behaviors. One of the simplest differences in firing phenotypes is that neurons are single-firing (exhibit only one action potential) or multi-firing (exhibit 2 or more action potentials). To determine if single- and multi-firing hDRG exhibit differences in intrinsic properties, firing phenotypes, and AP waveform properties, and if these properties could be used to predict multi-firing, we measured 22 electrophysiological properties by whole-cell patch-clamp electrophysiology of 94 hDRG neurons from 6 male and 4 female donors. We then analyzed the data using several machine learning models to determine if these properties could be used to predict multi-firing. We used 1000 iterations of Monte Carlo Cross Validation to split the data into different train and test sets and tested the Logistic Regression, k-Nearest Neighbors, Random Forest, Supported Vector Classification, and XGBoost machine learning models. All models tested had a greater than 80% accuracy on average, with Supported Vector Classification and XGBoost performing the best. We found that several properties correlated with multi-firing hDRG neurons and together could be used to predict multi-firing neurons in hDRG including a long decay time, a low rheobase, and long first spike latency. We also found that the hDRG models were able to predict multi-firing with 90% accuracy in mDRG. Targeting the neuronal properties that lead to multi-firing could elucidate better targets for treatment of chronic pain.
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Zeng M, Wu Z, Liang J, Gong A. Efficacy and safety of sodium hyaluronate combined with celecoxib for knee osteoarthritis: A systematic review and meta-analysis. Asian J Surg 2024; 47:1331-1338. [PMID: 38008631 DOI: 10.1016/j.asjsur.2023.11.077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/27/2023] [Accepted: 11/17/2023] [Indexed: 11/28/2023] Open
Abstract
Due to the large cost of joint replacement for surgical treatment of knee osteoarthritis, there are many complications in elderly patients, and there are many contraindications to surgery, and conservative treatment is still based on drugs. To further evaluate the efficacy and safety of sodium hyaluronate combined with celecoxib for the treatment of osteoarthritis of the knee. In total, 202 studies were screened, with a final selection of 9 RCTs involving 2339 participants; of these, 9 RCTs were included in the final meta-analysis. Treatment group reduces VAS (SMD = -1.61; 95 % CI [-2.25, -0.98]; I2 = 95 %; P < 0.00001) and adverse reactions (OR = 0.45; 95 % CI [0.22,0.94]; I2 = 0 %; P < 0.33); Meanwhile, improving Lysholm knee scores (SMD = 0.19; 95 % CI [-0.06, -0.44]; I2 = 76 %; P = 0.0004) and Clinical efficiency (OR = 0.31; 95 % CI [0.19,0.50]; I2 = 0 %; P < 0.00001). All indicators were superior to the control group. Our primary findings suggest that KOA treatment with celecoxib combined with sodium hyaluronate reduces VAS, while improving Lysholm scores and Clinical efficiency. In addition, we found that celecoxib combined with sodium hyaluronate treatment had fewer adverse effects than the control group, indicating that the combination is safe and effective in the treatment of KOA.
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Affiliation(s)
- Mengjie Zeng
- School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, 3004, Australia.
| | - Zhiquan Wu
- Department of Rehabilitation Medicine, Sanya Central Hospital, Sanya, PR China.
| | - Jinying Liang
- School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, 3004, Australia.
| | - Aimin Gong
- Department of Traditional Chinese Medicine, Hainan Medical University, Haikou, PR China.
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Gilchrist JM, Yang ND, Jiang V, Moyer BD. Pharmacologic Characterization of LTGO-33, a Selective Small Molecule Inhibitor of the Voltage-Gated Sodium Channel Na V1.8 with a Unique Mechanism of Action. Mol Pharmacol 2024; 105:233-249. [PMID: 38195157 DOI: 10.1124/molpharm.123.000789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/28/2023] [Accepted: 01/02/2024] [Indexed: 01/11/2024] Open
Abstract
Discovery and development of new molecules directed against validated pain targets is required to advance the treatment of pain disorders. Voltage-gated sodium channels (NaVs) are responsible for action potential initiation and transmission of pain signals. NaV1.8 is specifically expressed in peripheral nociceptors and has been genetically and pharmacologically validated as a human pain target. Selective inhibition of NaV1.8 can ameliorate pain while minimizing effects on other NaV isoforms essential for cardiac, respiratory, and central nervous system physiology. Here we present the pharmacology, interaction site, and mechanism of action of LTGO-33, a novel NaV1.8 small molecule inhibitor. LTGO-33 inhibited NaV1.8 in the nM potency range and exhibited over 600-fold selectivity against human NaV1.1-NaV1.7 and NaV1.9. Unlike prior reported NaV1.8 inhibitors that preferentially interacted with an inactivated state via the pore region, LTGO-33 was state-independent with similar potencies against closed and inactivated channels. LTGO-33 displayed species specificity for primate NaV1.8 over dog and rodent NaV1.8 and inhibited action potential firing in human dorsal root ganglia neurons. Using chimeras combined with mutagenesis, the extracellular cleft of the second voltage-sensing domain was identified as the key site required for channel inhibition. Biophysical mechanism of action studies demonstrated that LTGO-33 inhibition was relieved by membrane depolarization, suggesting the molecule stabilized the deactivated state to prevent channel opening. LTGO-33 equally inhibited wild-type and multiple NaV1.8 variants associated with human pain disorders. These collective results illustrate LTGO-33 inhibition via both a novel interaction site and mechanism of action previously undescribed in NaV1.8 small molecule pharmacologic space. SIGNIFICANCE STATEMENT: NaV1.8 sodium channels primarily expressed in peripheral pain-sensing neurons represent a validated target for the development of novel analgesics. Here we present the selective small molecule NaV1.8 inhibitor LTGO-33 that interdicts a distinct site in a voltage-sensor domain to inhibit channel opening. These results inform the development of new analgesics for pain disorders.
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Affiliation(s)
| | - Nien-Du Yang
- Latigo Biotherapeutics, Inc., Thousand Oaks, California
| | | | - Bryan D Moyer
- Latigo Biotherapeutics, Inc., Thousand Oaks, California
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Xu M, Wang Z, Xu G, Zhu M, Zhang D, Yan Y. Exploring gene signatures and regulatory networks in a rat model of sciatica: implications and validation in neuropathic pain. Front Mol Neurosci 2024; 16:1261217. [PMID: 38379852 PMCID: PMC10877633 DOI: 10.3389/fnmol.2023.1261217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 12/22/2023] [Indexed: 02/22/2024] Open
Abstract
Background Sciatica (neuropathic pain [NP]) is a common disease characterized by pain from radiation along the sciatic nerve. The aim of this study was to study the genes associated with chronic systolic injury of sciatic nerve (SCN-CCI) in rats by RNA-Seq technique, and to explore their potential as therapeutic targets. Methods Sciatic nerve rat model was obtained by ligation of sciatic nerve and divided into two groups: SCN-CCI group and Sham group. Behavioral assessments were performed to evaluate pain sensitivity, following which their spinal cord dorsal horn were resected and RNA sequencing was conducted to identify differentially expressed genes (DEGs). Bioinformatics and functional enrichment analysis was performed to identify promising DEGs and their related biological processes and pathways associated with SCN-CCI. PPI network analysis and hub gene identification were conducted. QRT-PCR, western blot, ELISA, and immunofluorescence staining were performed on rat models to validate the expression of these hub genes and investigate related proteins and inflammatory markers. Results The SCN-CCI rat model was successfully obtained, exhibiting increased pain sensitivity compared to the Sham group, as indicated by decreased mechanical allodynia thresholds, thermal latencies, and increased paw withdrawals. RNA-Seq analysis identified 117 DEGs in the SCN-CCI rat model, involved in various biological processes and pathways related to sciatica. PPI network analysis revealed hub genes, including Ly6g6e, which exhibited significant differential expression. QRT-PCR and Western blot analysis confirmed the expression patterns of these hub genes. Pain behavior assessment demonstrated reduced pain thresholds and increased paw flinching responses in the SCN-CCI group. Furthermore, the SCN-CCI group showed upregulated expression of Ly6g6e, increased protein levels of Ly6g6e, CGRP, and NGF, as well as elevated levels of IL-1β, MCP-1, and IL-6, and microglial cell activation in the spinal dorsal horn. ELISA results confirmed the increased levels of IL-1β, MCP-1, and IL-6 in the spinal dorsal horn. Conclusion These comprehensive findings provide valuable insights into the SCN-CCI rat model, DEGs associated with sciatica, hub genes (Ly6g6e as promising targets), pain behavior changes and molecular alterations.
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Affiliation(s)
| | | | | | | | | | - Yi Yan
- Department of Pain Medicine, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi, China
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Barton JR, Londregan AK, Alexander TD, Entezari AA, Covarrubias M, Waldman SA. Enteroendocrine cell regulation of the gut-brain axis. Front Neurosci 2023; 17:1272955. [PMID: 38027512 PMCID: PMC10662325 DOI: 10.3389/fnins.2023.1272955] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Enteroendocrine cells (EECs) are an essential interface between the gut and brain that communicate signals about nutrients, pain, and even information from our microbiome. EECs are hormone-producing cells expressed throughout the gastrointestinal epithelium and have been leveraged by pharmaceuticals like semaglutide (Ozempic, Wegovy), terzepatide (Mounjaro), and retatrutide (Phase 2) for diabetes and weight control, and linaclotide (Linzess) to treat irritable bowel syndrome (IBS) and visceral pain. This review focuses on role of intestinal EECs to communicate signals from the gut lumen to the brain. Canonically, EECs communicate information about the intestinal environment through a variety of hormones, dividing EECs into separate classes based on the hormone each cell type secretes. Recent studies have revealed more diverse hormone profiles and communication modalities for EECs including direct synaptic communication with peripheral neurons. EECs known as neuropod cells rapidly relay signals from gut to brain via a direct communication with vagal and primary sensory neurons. Further, this review discusses the complex information processing machinery within EECs, including receptors that transduce intraluminal signals and the ion channel complement that govern initiation and propagation of these signals. Deeper understanding of EEC physiology is necessary to safely treat devastating and pervasive conditions like irritable bowel syndrome and obesity.
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Affiliation(s)
- Joshua R. Barton
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Annie K. Londregan
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Tyler D. Alexander
- Department of Neurosciences, Thomas Jefferson University, Philadelphia, PA, United States
| | - Ariana A. Entezari
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Manuel Covarrubias
- Department of Neurosciences, Thomas Jefferson University, Philadelphia, PA, United States
| | - Scott A. Waldman
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, United States
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States
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Chen Q, Zhang XY, Wang YP, Fu YJ, Cao F, Xu YN, Kong JG, Tian NX, Xu Y, Wang Y. Unveiling adcyap1 as a protective factor linking pain and nerve regeneration through single-cell RNA sequencing of rat dorsal root ganglion neurons. BMC Biol 2023; 21:235. [PMID: 37880634 PMCID: PMC10601282 DOI: 10.1186/s12915-023-01742-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 10/17/2023] [Indexed: 10/27/2023] Open
Abstract
BACKGROUND Severe peripheral nerve injury (PNI) often leads to significant movement disorders and intractable pain. Therefore, promoting nerve regeneration while avoiding neuropathic pain is crucial for the clinical treatment of PNI patients. However, established animal models for peripheral neuropathy fail to accurately recapitulate the clinical features of PNI. Additionally, researchers usually investigate neuropathic pain and axonal regeneration separately, leaving the intrinsic relationship between the development of neuropathic pain and nerve regeneration after PNI unclear. To explore the underlying connections between pain and regeneration after PNI and provide potential molecular targets, we performed single-cell RNA sequencing and functional verification in an established rat model, allowing simultaneous study of the neuropathic pain and axonal regeneration after PNI. RESULTS First, a novel rat model named spared nerve crush (SNC) was created. In this model, two branches of the sciatic nerve were crushed, but the epineurium remained unsevered. This model successfully recapitulated both neuropathic pain and axonal regeneration after PNI, allowing for the study of the intrinsic link between these two crucial biological processes. Dorsal root ganglions (DRGs) from SNC and naïve rats at various time points after SNC were collected for single-cell RNA sequencing (scRNA-seq). After matching all scRNA-seq data to the 7 known DRG types, we discovered that the PEP1 and PEP3 DRG neuron subtypes increased in crushed and uncrushed DRG separately after SNC. Using experimental design scRNA-seq processing (EDSSP), we identified Adcyap1 as a potential gene contributing to both pain and nerve regeneration. Indeed, repeated intrathecal administration of PACAP38 mitigated pain and facilitated axonal regeneration, while Adcyap1 siRNA or PACAP6-38, an antagonist of PAC1R (a receptor of PACAP38) led to both mechanical hyperalgesia and delayed DRG axon regeneration in SNC rats. Moreover, these effects can be reversed by repeated intrathecal administration of PACAP38 in the acute phase but not the late phase after PNI, resulting in alleviated pain and promoted axonal regeneration. CONCLUSIONS Our study reveals that Adcyap1 is an intrinsic protective factor linking neuropathic pain and axonal regeneration following PNI. This finding provides new potential targets and strategies for early therapeutic intervention of PNI.
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Affiliation(s)
- Qi Chen
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Xi-Yin Zhang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Yu-Pu Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Yun-Jie Fu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Feng Cao
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Yi-Nuo Xu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Jin-Ge Kong
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Na-Xi Tian
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Yu Xu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China
| | - Yun Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China.
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
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GnRH Neuron Excitability and Action Potential Properties Change with Development But Are Not Affected by Prenatal Androgen Exposure. eNeuro 2022; 9:ENEURO.0362-22.2022. [PMID: 36446571 PMCID: PMC9765403 DOI: 10.1523/eneuro.0362-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/09/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons produce the final output from the brain to control pituitary gonadotropin secretion and thus regulate reproduction. Disruptions to gonadotropin secretion contribute to infertility, including polycystic ovary syndrome (PCOS) and idiopathic hypogonadotropic hypogonadism. PCOS is the leading cause of infertility in women and symptoms resembling PCOS are observed in girls at or near the time of pubertal onset, suggesting that alterations to the system likely occurred by that developmental period. Prenatally androgenized (PNA) female mice recapitulate many of the neuroendocrine phenotypes observed in PCOS, including altered time of puberty, disrupted reproductive cycles, increased circulating levels of testosterone, and altered gonadotropin secretion patterns. We tested the hypotheses that the intrinsic properties of GnRH neurons change with puberty and with PNA treatment. Whole-cell current-clamp recordings were made from GnRH neurons in brain slices from control and PNA females before puberty at three weeks of age and in adulthood to measure GnRH neuron excitability and action potential (AP) properties. GnRH neurons from adult females were more excitable and required less current to initiate action potential firing compared with three-week-old females. Further, the afterhyperpolarization (AHP) potential of the first spike was larger and its peak was delayed in adulthood. These results indicate development, not PNA, is a primary driver of changes to GnRH neuron intrinsic properties and suggest there may be developmentally-induced changes to voltage-gated ion channels in GnRH neurons that alter how these cells respond to synaptic input.
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Gale JR, Gedeon JY, Donnelly CJ, Gold MS. Local translation in primary afferents and its contribution to pain. Pain 2022; 163:2302-2314. [PMID: 35438669 PMCID: PMC9579217 DOI: 10.1097/j.pain.0000000000002658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 04/08/2022] [Indexed: 02/06/2023]
Abstract
ABSTRACT Chronic pain remains a significant problem due to its prevalence, impact, and limited therapeutic options. Progress in addressing chronic pain is dependent on a better understanding of underlying mechanisms. Although the available evidence suggests that changes within the central nervous system contribute to the initiation and maintenance of chronic pain, it also suggests that the primary afferent plays a critical role in all phases of the manifestation of chronic pain in most of those who suffer. Most notable among the changes in primary afferents is an increase in excitability or sensitization. A number of mechanisms have been identified that contribute to primary afferent sensitization with evidence for both increases in pronociceptive signaling molecules, such as voltage-gated sodium channels, and decreases in antinociceptive signaling molecules, such as voltage-dependent or calcium-dependent potassium channels. Furthermore, these changes in signaling molecules seem to reflect changes in gene expression as well as posttranslational processing. A mechanism of sensitization that has received far less attention, however, is the local or axonal translation of these signaling molecules. A growing body of evidence indicates that this process not only is dynamically regulated but also contributes to the initiation and maintenance of chronic pain. Here, we review the biology of local translation in primary afferents and its relevance to pain pathobiology.
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Affiliation(s)
- Jenna R Gale
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - Jeremy Y Gedeon
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | | | - Michael S Gold
- Corresponding author: Michael S Gold, PhD, Department of Neurobiology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, P: 412-383-5367,
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11
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Lunden LK, Kleggetveit IP, Schmelz M, Jorum E. Cold allodynia is correlated to paroxysmal and evoked mechanical pain in complex regional pain syndrome (CRPS). Scand J Pain 2022; 22:533-542. [PMID: 35429156 DOI: 10.1515/sjpain-2021-0208] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/09/2022] [Indexed: 02/28/2024]
Abstract
OBJECTIVES Mechanisms of complex regional pain syndrome (CRPS) are still debated. Identifying subgroups of patients have been attempted in the hope of linking clinical findings to possible mechanisms. The aim of the present study was to investigate whether subgroups of CRPS (based on quantitative sensory testing (QST)-results) differed with respect to different characteristics of pain like spontaneous ongoing or paroxysmal pain and mechanical dynamic allodynia. METHODS 61 CRPS-patients (type 1 and 2) were examined clinically and with QST, in affected and contralateral extremity, with assessment of thresholds for warmth, cold and heat-and cold pain. RESULTS 43 patients (20 men, 23 men) were diagnosed with CRPS 1 (70.5%) and 18 patients (8 women and 10 men) with CRPS 2 (29.5%). Three subgroups were defined based on thermal thresholds; A (thermal allodynia 22.9%), B (thermal hyposensitivity 37.3%), C (thermal allodynia and hyposensitivity 39.3%). Paroxysmal pain was more prevalent in patients with thermal allodynia (merging group A + C, 25/38-65.8%) compared to patients without thermal allodynia (group B, 5/23-21.7%) (p-value=0.00085). CONCLUSIONS We suggest that cold allodynia is based on hyper-excitability of very superficial skin nociceptors. The correlation between paroxysmal pain, allodynia to light touch and cold allodynia suggests that activity in those peripheral nociceptors can drive both, paroxysmal pain and spinal sensitization leading to stroke evoked allodynia. Mechanistically, the physical cold stimulus can unmask disease-related hyperexcitability by closure of temperature-sensitive potassium channels or induction of resurgent currents. Small fiber degeneration alone may not be the crucial mechanism in CRPS, nor explain pain.
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Affiliation(s)
- Lars Kristian Lunden
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Inge Petter Kleggetveit
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Martin Schmelz
- Department of Experimental Pain Research, MCTN, University of Heidelberg, Mannheim, Germany
| | - Ellen Jorum
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
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12
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Elleman AV, Du Bois J. Chemical and Biological Tools for the Study of Voltage-Gated Sodium Channels in Electrogenesis and Nociception. Chembiochem 2022; 23:e202100625. [PMID: 35315190 PMCID: PMC9359671 DOI: 10.1002/cbic.202100625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/22/2022] [Indexed: 12/17/2022]
Abstract
The malfunction and misregulation of voltage-gated sodium channels (NaV s) underlie in large part the electrical hyperexcitability characteristic of chronic inflammatory and neuropathic pain. NaV s are responsible for the initiation and propagation of electrical impulses (action potentials) in cells. Tissue and nerve injury alter the expression and localization of multiple NaV isoforms, including NaV 1.1, 1.3, and 1.6-1.9, resulting in aberrant action potential firing patterns. To better understand the role of NaV regulation, localization, and trafficking in electrogenesis and pain pathogenesis, a number of chemical and biological reagents for interrogating NaV function have been advanced. The development and application of such tools for understanding NaV physiology are the focus of this review.
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Affiliation(s)
- Anna V Elleman
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - J Du Bois
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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13
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Scorpion Neurotoxin Syb-prII-1 Exerts Analgesic Effect through Nav1.8 Channel and MAPKs Pathway. Int J Mol Sci 2022; 23:ijms23137065. [PMID: 35806068 PMCID: PMC9266357 DOI: 10.3390/ijms23137065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/19/2022] [Accepted: 06/21/2022] [Indexed: 02/06/2023] Open
Abstract
Trigeminal neuralgia (TN) is a common type of peripheral neuralgia in clinical practice, which is usually difficult to cure. Common analgesic drugs are difficult for achieving the desired analgesic effect. Syb-prII-1 is a β-type scorpion neurotoxin isolated from the scorpion venom of Buthus martensi Karsch (BmK). It has an important influence on the voltage-gated sodium channel (VGSCs), especially closely related to Nav1.8 and Nav1.9. To explore whether Syb-prII-1 has a good analgesic effect on TN, we established the Sprague Dawley (SD) rats’ chronic constriction injury of the infraorbital nerve (IoN-CCI) model. Behavioral, electrophysiological, Western blot, and other methods were used to verify the model. It was found that Syb-prII-1 could significantly relieve the pain behavior of IoN-CCI rats. After Syb-prII-1 was given, the phosphorylation level of the mitogen-activated protein kinases (MAPKs) pathway showed a dose-dependent decrease after IoN-CCI injury. Moreover, Syb-prII-1(4.0 mg/kg) could significantly change the steady-state activation and inactivation curves of Nav1.8. The steady-state activation and inactivation curves of Nav1.9 were similar to those of Nav1.8, but there was no significant difference. It was speculated that it might play an auxiliary role. The binding mode, critical residues, and specific interaction type of Syb-prII-1 and VSD2rNav1.8 were clarified with computational simulation methods. Our results indicated that Syb-prII-1 could provide a potential treatment for TN by acting on the Nav1.8 target.
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14
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Pergolizzi JV, Gharibo C, Magnusson P, Breve F, LeQuang JA, Varrassi G. Pharmacotherapeutic management of trigeminal neuropathic pain: an update. Expert Opin Pharmacother 2022; 23:1155-1164. [PMID: 35695796 DOI: 10.1080/14656566.2022.2087507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Guidelines recommend a number of pharmacotherapeutic options used as monotherapy or in combination with others for treating the pain of trigeminal neuropathy. AREAS COVERED The authors examine the pharmacotherapeutic options for treating trigeminal neuralgia and supporting evidence in the literature. Guidelines reported the most effective treatment for trigeminal neuropathy, in particular trigeminal neuralgia, appears to be carbamazepine or oxcabazepine, but side effects can be treatment limiting. Lamotrigine and gabapentin are also recommended in guidance. In real-world clinical practice, baclofen, cannabinoids, eslicarbazepine, levetiracetam, brivaracetam, lidocaine, misoprostol, opioids, phenytoin, fosphenytoin, pimozide, sodium valproate, sumatriptan, tizanidine, tocainide, tricyclic antidepressants, and vixotrigine are sometimes used, either as monotherapy or in combination. The relatively small patient population has limited the number of large-scale studies and there is limited evidence on which to base prescribing choices. EXPERT OPINION While there is no optimal pharmacotherapy for treating trigeminal neuropathy, advancements in our understanding of the underlying mechanisms of this condition and drug development indicate promise for NaV inhibitors, despite the fact that not all patients respond to them and they may have potentially treatment-limiting side effects. Nevertheless, better understanding of NaV channels may be important avenues for future drug development for trigeminal neuropathy.
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Affiliation(s)
| | | | - Peter Magnusson
- Centre for Research and Development, Region Gävleborg/Uppsala University, Gävle, Sweden.,Department of Medicine, Cardiology Research Unit, Karolinska Institutet, Stockholm, Sweden
| | - Frank Breve
- Department of Pharmacy Practice, Temple University School of Pharmacy, Philadelphia, Pennsylvania, USA
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15
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Xue Y, Kremer M, Muniz Moreno MDM, Chidiac C, Lorentz R, Birling MC, Barrot M, Herault Y, Gaveriaux-Ruff C. The Human SCN9AR185H Point Mutation Induces Pain Hypersensitivity and Spontaneous Pain in Mice. Front Mol Neurosci 2022; 15:913990. [PMID: 35769334 PMCID: PMC9234669 DOI: 10.3389/fnmol.2022.913990] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.7 is encoded by SCN9A gene and plays a critical role in pain sensitivity. Several SCN9A gain-of-function (GOF) mutations have been found in patients with small fiber neuropathy (SFN) having chronic pain, including the R185H mutation. However, for most of these variants, their involvement in pain phenotype still needs to be experimentally elucidated. In order to delineate the impact of R185H mutation on pain sensitivity, we have established the Scn9aR185H mutant mouse model using the CRISPR/Cas9 technology. The Scn9aR185H mutant mice show no cellular alteration in the dorsal root ganglia (DRG) containing cell bodies of sensory neurons and no alteration of growth or global health state. Heterozygous and homozygous animals of both sexes were investigated for pain sensitivity. The mutant mice were more sensitive than the wild-type mice in the tail flick and hot plate tests, acetone, and von Frey tests for sensitivity to heat, cold, and touch, respectively, although with sexual dimorphic effects. The newly developed bioinformatic pipeline, Gdaphen is based on general linear model (GLM) and random forest (RF) classifiers as well as a multifactor analysis of mixed data and shows the qualitative and quantitative variables contributing the most to the pain phenotype. Using Gdaphen, tail flick, Hargreaves, hot plate, acetone, cold plate, and von Frey tests, sex and genotype were found to be contributing most to the pain phenotype. Importantly, the mutant animals displayed spontaneous pain as assessed in the conditioned place preference (CPP) assay. Altogether, our results indicate that Scn9aR185H mice show a pain phenotype, suggesting that the SCN9AR185H mutation identified in patients with SFN having chronic pain contributes to their symptoms. Therefore, we provide genetic evidence for the fact that this mutation in Nav1.7 channel plays an important role in nociception and in the pain experienced by patients with SFN who have this mutation. These findings should aid in exploring further pain treatments based on the Nav1.7 channel.
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Affiliation(s)
- Yaping Xue
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Mélanie Kremer
- Centre National de la Recherche Scientifique (CNRS), Institut des Neurosciences Cellulaires et Intégratives (INCI), Université de Strasbourg, Strasbourg, France
| | - Maria del Mar Muniz Moreno
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Celeste Chidiac
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Romain Lorentz
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), CELPHEDIA-PHENOMIN-Institut Clinique de la Souris, (PHENOMIN-ICS), Université de Strasbourg, Illkirch, France
| | - Marie-Christine Birling
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), CELPHEDIA-PHENOMIN-Institut Clinique de la Souris, (PHENOMIN-ICS), Université de Strasbourg, Illkirch, France
| | - Michel Barrot
- Centre National de la Recherche Scientifique (CNRS), Institut des Neurosciences Cellulaires et Intégratives (INCI), Université de Strasbourg, Strasbourg, France
| | - Yann Herault
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), CELPHEDIA-PHENOMIN-Institut Clinique de la Souris, (PHENOMIN-ICS), Université de Strasbourg, Illkirch, France
- *Correspondence: Yann Herault,
| | - Claire Gaveriaux-Ruff
- Centre National de la Recherche Scientifique (CNRS), Institut de la Santé et de la Recherche Médicale (INSERM), Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
- Centre National de la Recherche Scientifique (CNRS) UMR 7242, Université de Strasbourg, Illkirch, France
- Claire Gaveriaux-Ruff,
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16
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Xiao Y, Theile JW, Zybura A, Pan Y, Lin Z, Cummins TR. A-type FHFs mediate resurgent currents through TTX-resistant voltage-gated sodium channels. eLife 2022; 11:77558. [PMID: 35441593 PMCID: PMC9071269 DOI: 10.7554/elife.77558] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Resurgent currents (INaR) produced by voltage-gated sodium channels are required for many neurons to maintain high-frequency firing, and contribute to neuronal hyperexcitability and disease pathophysiology. Here we show, for the first time, that INaR can be reconstituted in a heterologous system by co-expression of sodium channel α-subunits and A-type fibroblast growth factor homologous factors (FHFs). Specifically, A-type FHFs induces INaR from Nav1.8, Nav1.9 tetrodotoxin-resistant neuronal channels and, to a lesser extent, neuronal Nav1.7 and cardiac Nav1.5 channels. Moreover, we identified the N-terminus of FHF as the critical molecule responsible for A-type FHFs-mediated INaR. Among the FHFs, FHF4A is the most important isoform for mediating Nav1.8 and Nav1.9 INaR. In nociceptive sensory neurons, FHF4A knockdown significantly reduces INaR amplitude and the percentage of neurons that generate INaR, substantially suppressing excitability. Thus, our work reveals a novel molecular mechanism underlying TTX-resistant INaR generation and provides important potential targets for pain treatment.
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Affiliation(s)
- Yucheng Xiao
- Biology Department, Indiana University - Purdue University Indianapolis, Indianapolis, United States
| | | | - Agnes Zybura
- Paul and Carole Stark Neurosciences Research Institute, Indiana University, Indianapolis, United States
| | - Yanling Pan
- Biology Department, Indiana University - Purdue University Indianapolis, Indianapolis, United States
| | | | - Theodore R Cummins
- Biology Department, Indiana University - Purdue University Indianapolis, Indianapolis, United States
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17
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Tavares-Ferreira D, Shiers S, Ray PR, Wangzhou A, Jeevakumar V, Sankaranarayanan I, Cervantes AM, Reese JC, Chamessian A, Copits BA, Dougherty PM, Gereau RW, Burton MD, Dussor G, Price TJ. Spatial transcriptomics of dorsal root ganglia identifies molecular signatures of human nociceptors. Sci Transl Med 2022; 14:eabj8186. [PMID: 35171654 PMCID: PMC9272153 DOI: 10.1126/scitranslmed.abj8186] [Citation(s) in RCA: 160] [Impact Index Per Article: 80.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nociceptors are specialized sensory neurons that detect damaging or potentially damaging stimuli and are found in the dorsal root ganglia (DRG) and trigeminal ganglia. These neurons are critical for the generation of neuronal signals that ultimately create the perception of pain. Nociceptors are also primary targets for treating acute and chronic pain. Single-cell transcriptomics on mouse nociceptors has transformed our understanding of pain mechanisms. We sought to generate equivalent information for human nociceptors with the goal of identifying transcriptomic signatures of nociceptors, identifying species differences and potential drug targets. We used spatial transcriptomics to molecularly characterize transcriptomes of single DRG neurons from eight organ donors. We identified 12 clusters of human sensory neurons, 5 of which are C nociceptors, as well as 1 C low-threshold mechanoreceptors (LTMRs), 1 Aβ nociceptor, 2 Aδ, 2 Aβ, and 1 proprioceptor subtypes. By focusing on expression profiles for ion channels, G protein-coupled receptors (GPCRs), and other pharmacological targets, we provided a rich map of potential drug targets in the human DRG with direct comparison to mouse sensory neuron transcriptomes. We also compared human DRG neuronal subtypes to nonhuman primates showing conserved patterns of gene expression among many cell types but divergence among specific nociceptor subsets. Last, we identified sex differences in human DRG subpopulation transcriptomes, including a marked increase in calcitonin-related polypeptide alpha (CALCA) expression in female pruritogen receptor-enriched nociceptors. This comprehensive spatial characterization of human nociceptors might open the door to development of better treatments for acute and chronic pain disorders.
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Affiliation(s)
- Diana Tavares-Ferreira
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA.,Corresponding author: (T.J.P.); (D.T.-F.)
| | - Stephanie Shiers
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Pradipta R. Ray
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Andi Wangzhou
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Vivekanand Jeevakumar
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Ishwarya Sankaranarayanan
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | | | | | - Alexander Chamessian
- Department of Anesthesiology, Washington University Pain Center, St. Louis, MO 63110, USA
| | - Bryan A. Copits
- Department of Anesthesiology, Washington University Pain Center, St. Louis, MO 63110, USA
| | - Patrick M. Dougherty
- Department of Pain Medicine, Division of Anesthesiology and Critical Care, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Robert W. Gereau
- Department of Anesthesiology, Washington University Pain Center, St. Louis, MO 63110, USA
| | - Michael D. Burton
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Gregory Dussor
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Theodore J. Price
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA.,Corresponding author: (T.J.P.); (D.T.-F.)
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18
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Tavares-Ferreira D, Shiers S, Ray PR, Wangzhou A, Jeevakumar V, Sankaranarayanan I, Cervantes AM, Reese JC, Chamessian A, Copits BA, Dougherty PM, Gereau RW, Burton MD, Dussor G, Price TJ. Spatial transcriptomics of dorsal root ganglia identifies molecular signatures of human nociceptors. Sci Transl Med 2022. [DOI: 10.1126/scitranslmed.abj8186\] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Nociceptors are specialized sensory neurons that detect damaging or potentially damaging stimuli and are found in the dorsal root ganglia (DRG) and trigeminal ganglia. These neurons are critical for the generation of neuronal signals that ultimately create the perception of pain. Nociceptors are also primary targets for treating acute and chronic pain. Single-cell transcriptomics on mouse nociceptors has transformed our understanding of pain mechanisms. We sought to generate equivalent information for human nociceptors with the goal of identifying transcriptomic signatures of nociceptors, identifying species differences and potential drug targets. We used spatial transcriptomics to molecularly characterize transcriptomes of single DRG neurons from eight organ donors. We identified 12 clusters of human sensory neurons, 5 of which are C nociceptors, as well as 1 C low-threshold mechanoreceptors (LTMRs), 1 Aβ nociceptor, 2 Aδ, 2 Aβ, and 1 proprioceptor subtypes. By focusing on expression profiles for ion channels, G protein–coupled receptors (GPCRs), and other pharmacological targets, we provided a rich map of potential drug targets in the human DRG with direct comparison to mouse sensory neuron transcriptomes. We also compared human DRG neuronal subtypes to nonhuman primates showing conserved patterns of gene expression among many cell types but divergence among specific nociceptor subsets. Last, we identified sex differences in human DRG subpopulation transcriptomes, including a marked increase in calcitonin-related polypeptide alpha (
CALCA
) expression in female pruritogen receptor–enriched nociceptors. This comprehensive spatial characterization of human nociceptors might open the door to development of better treatments for acute and chronic pain disorders.
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Affiliation(s)
- Diana Tavares-Ferreira
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Stephanie Shiers
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Pradipta R. Ray
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Andi Wangzhou
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Vivekanand Jeevakumar
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Ishwarya Sankaranarayanan
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | | | | | - Alexander Chamessian
- Department of Anesthesiology , Washington University Pain Center, St. Louis, MO 63110, USA
| | - Bryan A. Copits
- Department of Anesthesiology , Washington University Pain Center, St. Louis, MO 63110, USA
| | - Patrick M. Dougherty
- Department of Pain Medicine, Division of Anesthesiology and Critical Care, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Robert W. Gereau
- Department of Anesthesiology , Washington University Pain Center, St. Louis, MO 63110, USA
| | - Michael D. Burton
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Gregory Dussor
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
| | - Theodore J. Price
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson TX 75080, USA
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19
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Multitarget nociceptor sensitization by a promiscuous peptide from the venom of the King Baboon spider. Proc Natl Acad Sci U S A 2022; 119:2110932119. [PMID: 35074873 PMCID: PMC8812547 DOI: 10.1073/pnas.2110932119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 12/15/2022] Open
Abstract
The King Baboon spider, Pelinobius muticus, is a burrowing African tarantula. Its impressive size and appealing coloration are tempered by reports describing severe localized pain, swelling, itchiness, and muscle cramping after accidental envenomation. Hyperalgesia is the most prominent symptom after bites from P. muticus, but the molecular basis by which the venom induces pain is unknown. Proteotranscriptomic analysis of P. muticus venom uncovered a cysteine-rich peptide, δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a), that elicited nocifensive behavior when injected into mice. In small dorsal root ganglion neurons, synthetic δ/κ-TRTX-Pm1a (sPm1a) induced hyperexcitability by enhancing tetrodotoxin-resistant sodium currents, impairing repolarization and lowering the threshold of action potential firing, consistent with the severe pain associated with envenomation. The molecular mechanism of nociceptor sensitization by sPm1a involves multimodal actions over several ion channel targets, including NaV1.8, KV2.1, and tetrodotoxin-sensitive NaV channels. The promiscuous targeting of peptides like δ/κ-TRTX-Pm1a may be an evolutionary adaptation in pain-inducing defensive venoms.
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20
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Villalba‐Riquelme E, de la Torre‐Martínez R, Fernández‐Carvajal A, Ferrer‐Montiel A. Paclitaxel in vitro reversibly sensitizes the excitability of IB4(-) and IB4(+) sensory neurons from male and female rats. Br J Pharmacol 2022; 179:3693-3710. [PMID: 35102580 PMCID: PMC9311666 DOI: 10.1111/bph.15809] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/03/2022] [Accepted: 01/23/2022] [Indexed: 11/27/2022] Open
Affiliation(s)
- Eva Villalba‐Riquelme
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE)Universitas Miguel HernándezElcheSpain
| | | | - Asia Fernández‐Carvajal
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE)Universitas Miguel HernándezElcheSpain
| | - Antonio Ferrer‐Montiel
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE)Universitas Miguel HernándezElcheSpain
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21
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Zheng XQ, Wu YH, Huang JF, Wu AM. Neurophysiological mechanisms of cancer-induced bone pain. J Adv Res 2022; 35:117-127. [PMID: 35003797 PMCID: PMC8721251 DOI: 10.1016/j.jare.2021.06.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 05/23/2021] [Accepted: 06/08/2021] [Indexed: 12/16/2022] Open
Abstract
Background Cancer-induced Bone Pain (CIBP) is an important factor affecting their quality of life of cancer survivors. In addition, current clinical practice and scientific research suggest that neuropathic pain is a representative component of CIBP. However, given the variability of cancer conditions and the complexity of neuropathic pain, related mechanisms have been continuously supplemented but have not been perfected. Aim of Review Therefore, the current review highlights the latest progress in basic research on the field and proposes potential therapeutic targets, representative drugs and upcoming therapies. Key Scientific Concepts of Review Notably, factors such as central sensitization, neuroinflammation, glial cell activation and an acidic environment are considered to be related to neuropathic pain in CIBP. Nonetheless, further research is needed to ascertain the mechanism of CIBP in order to develop highly effective drugs. Moreover, more attention needs to be paid to the care of patients with advanced cancer.
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Affiliation(s)
- Xuan-Qi Zheng
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Zhejiang Provincial Key Laboratory of Orthopaedics, Wenzhou, Zhejiang, 325027, China
- Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Yu-hao Wu
- Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Jin-feng Huang
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Zhejiang Provincial Key Laboratory of Orthopaedics, Wenzhou, Zhejiang, 325027, China
- Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Ai-Min Wu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Zhejiang Provincial Key Laboratory of Orthopaedics, Wenzhou, Zhejiang, 325027, China
- Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
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22
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Chidiac C, Xue Y, Muniz Moreno MDM, Bakr Rasheed AA, Lorentz R, Birling MC, Gaveriaux-Ruff C, Herault Y. The Human SCN10A G1662S Point Mutation Established in Mice Impacts on Mechanical, Heat, and Cool Sensitivity. Front Pharmacol 2021; 12:780132. [PMID: 34925037 PMCID: PMC8671994 DOI: 10.3389/fphar.2021.780132] [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] [Received: 09/20/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel NAV1.8 is expressed in primary nociceptive neurons and is involved in pain transmission. Mutations in the SCN10A gene (encoding NAV1.8 channel) have been identified in patients with idiopathic painful small fiber neuropathy (SFN) including the SCN10AG1662S gain-of-function mutation. However, the role of this mutation in pain sensation remains unknown. We have generated the first mouse model for the G1662S mutation by using homologous recombination in embryonic stem cells. The corresponding Scn10aG1663S mouse line has been analyzed for Scn10a expression, intraepidermal nerve fiber density (IENFD), and nociception using behavioral tests for thermal and mechanical sensitivity. The Scn10aG1663S mutants had a similar Scn10a expression level in dorsal root ganglia (DRG) to their wild-type littermates and showed normal IENFD in hindpaw skin. Mutant mice were more sensitive to touch than wild types in the von Frey test. In addition, sexual dimorphism was observed for several pain tests, pointing to the relevance of performing the phenotypical assessment in both sexes. Female homozygous mutants tended to be more sensitive to cooling stimuli in the acetone test. For heat sensitivity, male homozygous mutants showed shorter latencies to radiant heat in the Hargreaves test while homozygous females had longer latencies in the tail flick test. In addition, mutant males displayed a shorter reaction latency on the 54°C hot plate. Collectively, Scn10aG1663S mutant mice show a moderate but consistent increased sensitivity in behavioral tests of nociception. This altered nociception found in Scn10aG1663S mice demonstrates that the corresponding G1662 mutation of SCN10A found in SFN patients with pain contributes to their pain symptoms.
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Affiliation(s)
- Celeste Chidiac
- CNRS, INSERM Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Yaping Xue
- CNRS, INSERM Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Maria Del Mar Muniz Moreno
- CNRS, INSERM Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Ameer Abu Bakr Rasheed
- CNRS, INSERM Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Romain Lorentz
- CNRS, INSERM, PHENOMIN-Institut Clinique de la Souris, Université de Strasbourg, Illkirch, France
| | - Marie-Christine Birling
- CNRS, INSERM, PHENOMIN-Institut Clinique de la Souris, Université de Strasbourg, Illkirch, France
| | - Claire Gaveriaux-Ruff
- CNRS, INSERM Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Yann Herault
- CNRS, INSERM Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France.,CNRS, INSERM, PHENOMIN-Institut Clinique de la Souris, Université de Strasbourg, Illkirch, France
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23
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Wu X, Hong L. Calmodulin Interactions with Voltage-Gated Sodium Channels. Int J Mol Sci 2021; 22:ijms22189798. [PMID: 34575961 PMCID: PMC8472079 DOI: 10.3390/ijms22189798] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 02/06/2023] Open
Abstract
Calmodulin (CaM) is a small protein that acts as a ubiquitous signal transducer and regulates neuronal plasticity, muscle contraction, and immune response. It interacts with ion channels and plays regulatory roles in cellular electrophysiology. CaM modulates the voltage-gated sodium channel gating process, alters sodium current density, and regulates sodium channel protein trafficking and expression. Many mutations in the CaM-binding IQ domain give rise to diseases including epilepsy, autism, and arrhythmias by interfering with CaM interaction with the channel. In the present review, we discuss CaM interactions with the voltage-gated sodium channel and modulators involved in CaM regulation, as well as summarize CaM-binding IQ domain mutations associated with human diseases in the voltage-gated sodium channel family.
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24
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Tidball AM, Lopez-Santiago LF, Yuan Y, Glenn TW, Margolis JL, Clayton Walker J, Kilbane EG, Miller CA, Martina Bebin E, Scott Perry M, Isom LL, Parent JM. Variant-specific changes in persistent or resurgent sodium current in SCN8A-related epilepsy patient-derived neurons. Brain 2021; 143:3025-3040. [PMID: 32968789 DOI: 10.1093/brain/awaa247] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 05/27/2020] [Accepted: 06/19/2020] [Indexed: 12/12/2022] Open
Abstract
Missense variants in the SCN8A voltage-gated sodium channel gene are linked to early-infantile epileptic encephalopathy type 13, also known as SCN8A-related epilepsy. These patients exhibit a wide spectrum of intractable seizure types, severe developmental delay, movement disorders, and elevated risk of sudden unexpected death in epilepsy. The mechanisms by which SCN8A variants lead to epilepsy are poorly understood, although heterologous expression systems and mouse models have demonstrated altered sodium current properties. To investigate these mechanisms using a patient-specific model, we generated induced pluripotent stem cells from three patients with missense variants in SCN8A: p.R1872>L (Patient 1); p.V1592>L (Patient 2); and p.N1759>S (Patient 3). Using small molecule differentiation into excitatory neurons, induced pluripotent stem cell-derived neurons from all three patients displayed altered sodium currents. Patients 1 and 2 had elevated persistent current, while Patient 3 had increased resurgent current compared to controls. Neurons from all three patients displayed shorter axon initial segment lengths compared to controls. Further analyses focused on one of the patients with increased persistent sodium current (Patient 1) and the patient with increased resurgent current (Patient 3). Excitatory cortical neurons from both patients had prolonged action potential repolarization. Using doxycycline-inducible expression of the neuronal transcription factors neurogenin 1 and 2 to synchronize differentiation of induced excitatory cortical-like neurons, we investigated network activity and response to pharmacotherapies. Both small molecule differentiated and induced patient neurons displayed similar abnormalities in action potential repolarization. Patient induced neurons showed increased burstiness that was sensitive to phenytoin, currently a standard treatment for SCN8A-related epilepsy patients, or riluzole, an FDA-approved drug used in amyotrophic lateral sclerosis and known to block persistent and resurgent sodium currents, at pharmacologically relevant concentrations. Patch-clamp recordings showed that riluzole suppressed spontaneous firing and increased the action potential firing threshold of patient-derived neurons to more depolarized potentials. Two of the patients in this study were prescribed riluzole off-label. Patient 1 had a 50% reduction in seizure frequency. Patient 3 experienced an immediate and dramatic seizure reduction with months of seizure freedom. An additional patient with a SCN8A variant in domain IV of Nav1.6 (p.V1757>I) had a dramatic reduction in seizure frequency for several months after starting riluzole treatment, but then seizures recurred. Our results indicate that patient-specific neurons are useful for modelling SCN8A-related epilepsy and demonstrate SCN8A variant-specific mechanisms. Moreover, these findings suggest that patient-specific neuronal disease modelling offers a useful platform for discovering precision epilepsy therapies.
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Affiliation(s)
- Andrew M Tidball
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - Yukun Yuan
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Trevor W Glenn
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - J Clayton Walker
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Emma G Kilbane
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - E Martina Bebin
- Department of Neurology, University of Alabama Birmingham School of Medicine, Birmingham, AL, USA.,Department of Pediatrics, University of Alabama Birmingham School of Medicine, Birmingham, AL, USA
| | - M Scott Perry
- Cook Children's Health Care System, Fort Worth, Texas, USA
| | - Lori L Isom
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.,Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Jack M Parent
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.,Ann Arbor VA Healthcare System, Ann Arbor, MI, USA
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25
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Verma P, Eaton M, Kienle A, Flockerzi D, Yang Y, Ramkrishna D. Examining Sodium and Potassium Channel Conductances Involved in Hyperexcitability of Chemotherapy-Induced Peripheral Neuropathy: A Mathematical and Cell Culture-Based Study. Front Comput Neurosci 2020; 14:564980. [PMID: 33178002 PMCID: PMC7593680 DOI: 10.3389/fncom.2020.564980] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 08/02/2020] [Indexed: 11/13/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a prevalent, painful side effect which arises due to a number of chemotherapy agents. CIPN can have a prolonged effect on quality of life. Chemotherapy treatment is often reduced or stopped altogether because of the severe pain. Currently, there are no FDA-approved treatments for CIPN partially due to its complex pathogenesis in multiple pathways involving a variety of channels, specifically, voltage-gated ion channels. One aspect of neuropathic pain in vitro is hyperexcitability in dorsal root ganglia (DRG) peripheral sensory neurons. Our study employs bifurcation theory to investigate the role of voltage-gated ion channels in inducing hyperexcitability as a consequence of spontaneous firing due to the common chemotherapy agent paclitaxel. Our mathematical investigation of a reductionist DRG neuron model comprised of sodium channel Nav1.7, sodium channel Nav1.8, delayed rectifier potassium channel, A-type transient potassium channel, and a leak channel suggests that Nav1.8 and delayed rectifier potassium channel conductances are critical for hyperexcitability of small DRG neurons. Introducing paclitaxel into the model, our bifurcation analysis predicts that hyperexcitability is highest for a medium dose of paclitaxel, which is supported by multi-electrode array (MEA) recordings. Furthermore, our findings using MEA reveal that Nav1.8 blocker A-803467 and delayed rectifier potassium enhancer L-alpha-phosphatidyl-D-myo-inositol 4,5-diphosphate, dioctanoyl (PIP2) can reduce paclitaxel-induced hyperexcitability of DRG neurons. Our approach can be readily extended and used to investigate various other contributors of hyperexcitability in CIPN.
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Affiliation(s)
- Parul Verma
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN, United States
| | - Muriel Eaton
- Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Achim Kienle
- Process Synthesis and Dynamics Group, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- Chair for Automation/Modeling, Otto von Guericke University, Magdeburg, Germany
| | - Dietrich Flockerzi
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- Otto von Guericke University, Magdeburg, Germany
| | - Yang Yang
- Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Doraiswami Ramkrishna
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN, United States
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26
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Adney SK, Millichap JJ, DeKeyser JM, Abramova T, Thompson CH, George AL. Functional and pharmacological evaluation of a novel SCN2A variant linked to early-onset epilepsy. Ann Clin Transl Neurol 2020; 7:1488-1501. [PMID: 32750235 PMCID: PMC7480906 DOI: 10.1002/acn3.51105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVE We identified a novel de novo SCN2A variant (M1879T) associated with infantile-onset epilepsy that responded dramatically to sodium channel blocker antiepileptic drugs. We analyzed the functional and pharmacological consequences of this variant to establish pathogenicity, and to correlate genotype with phenotype and clinical drug response. METHODS The clinical and genetic features of an infant boy with epilepsy are presented. We investigated the effect of the variant using heterologously expressed recombinant human NaV 1.2 channels. We performed whole-cell patch clamp recording to determine the functional consequences and response to carbamazepine. RESULTS The M1879T variant caused disturbances in channel inactivation including substantially depolarized voltage dependence of inactivation, slower time course of inactivation, and enhanced resurgent current that collectively represent a gain-of-function. Carbamazepine partially normalized the voltage dependence of inactivation and produced use-dependent block of the variant channel at high pulsing frequencies. Carbamazepine also suppresses resurgent current conducted by M1879T channels, but this effect was explained primarily by reducing the peak transient current. Molecular modeling suggests that the M1879T variant disrupts contacts with nearby residues in the C-terminal domain of the channel. INTERPRETATION Our study demonstrates the value of conducting functional analyses of SCN2A variants of unknown significance to establish pathogenicity and genotype-phenotype correlations. We also show concordance of in vitro pharmacology using heterologous cells with the drug response observed clinically in a case of SCN2A-associated epilepsy.
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Affiliation(s)
- Scott K Adney
- Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, 60611, USA
| | - John J Millichap
- Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, 60611, USA.,Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, 60611, USA
| | - Jean-Marc DeKeyser
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Tatiana Abramova
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Christopher H Thompson
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Alfred L George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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27
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Meredith FL, Rennie KJ. Persistent and resurgent Na + currents in vestibular calyx afferents. J Neurophysiol 2020; 124:510-524. [PMID: 32667253 DOI: 10.1152/jn.00124.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Vestibular afferent neurons convey information from hair cells in the peripheral vestibular end organs to central nuclei. Primary vestibular afferent neurons can fire action potentials at high rates and afferent firing patterns vary with the position of nerve terminal endings in vestibular neuroepithelia. Terminals contact hair cells as small bouton or large calyx endings. To investigate the role of Na+ currents (INa) in firing mechanisms, we investigated biophysical properties of INa in calyx-bearing afferents. Whole cell patch-clamp recordings were made from calyx terminals in thin slices of gerbil crista at different postnatal ages: immature [postnatal day (P)5-P8, young (P13-P15), and mature (P30-P45)]. A large transient Na+ current (INaT) was completely blocked by 300 nM tetrodotoxin (TTX) in mature calyces. In addition, INaT was accompanied by much smaller persistent Na+ currents (INaP) and distinctive resurgent Na+ currents (INaR), which were also blocked by TTX. ATX-II, a toxin that slows Na+ channel inactivation, enhanced INaP in immature and mature calyces. 4,9-Anhydro-TTX (4,9-ah-TTX), which selectively blocks Nav1.6 channels, abolished the enhanced INa in mature, but not immature, calyces. Therefore, Nav1.6 channels mediate a component of INaT and INaP in mature calyces, but are minimally expressed at early postnatal days. INaR was expressed in less than one-third of calyces at P6-P8, but expression increased with development, and in mature cristae INaR was frequently found in peripheral calyces. INaR served to increase the availability of Na+ channels following brief membrane depolarizations. In current clamp, the rate and regularity of action potential firing decreased in mature peripheral calyces following 4,9-ah-TTX application. Therefore, Nav1.6 channels are upregulated during development, contribute to INaT, INaP, and INaR, and may regulate excitability by enabling higher mean discharge rates in a subpopulation of mature calyx afferents.NEW & NOTEWORTHY Action potential firing patterns differ between groups of afferent neurons innervating vestibular epithelia. We investigated the biophysical properties of Na+ currents in specialized vestibular calyx afferent terminals during postnatal development. Mature calyces express Na+ currents with transient, persistent, and resurgent components. Nav1.6 channels contribute to resurgent Na+ currents and may enhance firing in peripheral calyx afferents. Understanding Na+ channels that contribute to vestibular nerve responses has implications for developing new treatments for vestibular dysfunction.
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Affiliation(s)
- Frances L Meredith
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado
| | - Katherine J Rennie
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado.,Department of Physiology & Biophysics, University of Colorado School of Medicine, Aurora, Colorado
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28
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Genomic analysis of 21 patients with corneal neuralgia after refractive surgery. Pain Rep 2020; 5:e826. [PMID: 32766464 PMCID: PMC7390595 DOI: 10.1097/pr9.0000000000000826] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/13/2020] [Indexed: 12/19/2022] Open
Abstract
Background Refractive surgery, specifically laser-assisted in situ keratomileusis and photorefractive keratectomy, are widely applied procedures to treat myopia, hyperopia, and astigmatism. After surgery, a subgroup of cases suffers from persistent and intractable pain of obscure etiology, thought to be neuropathic. We aimed to investigate the contribution of genomic factors in the pathogenesis of these patients with corneal neuralgia. Methods We enrolled 21 cases (6 males and 15 females) from 20 unrelated families, who reported persistent pain (>3 months), after refractive surgery (20 laser-assisted in situ keratomileusis and 1 photorefractive keratectomy patients). Whole-exome sequencing and gene-based association test were performed. Results Whole-exome sequencing demonstrated low-frequency variants (allele frequency < 0.05) in electrogenisome-related ion channels and cornea-expressed collagens, most frequently in SCN10A (5 cases), SCN9A (4 cases), TRPV1 (4 cases), CACNA1H and CACNA2D2 (5 cases each), COL5A1 (6 cases), COL6A3 (5 cases), and COL4A2 (4 cases). Two variants, p.K655R of SCN9A and p.Q85R of TRPV1, were previously characterized as gain-of-function. Gene-based association test assessing "damaging" missense variants against gnomAD exome database (non-Finnish European or global), identified a gene, SLC9A3R1, with statistically significant effect (odds ratio = 17.09 or 17.04; Bonferroni-corrected P-value < 0.05). Conclusion These findings in a small patient cohort did not identify a common gene/variant among most of these cases, as found in other disorders, for example small-fiber neuropathy. Further studies of these candidate genes/variants might enhance understanding of the role of genetic factors in the pathogenesis of corneal neuralgia.
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29
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Plakhova VB, Penniyaynen VA, Rogachevskii IV, Podzorova SA, Khalisov MM, Ankudinov AV, Krylov BV. Dual mechanism of modulation of Na V1.8 sodium channels by ouabain. Can J Physiol Pharmacol 2020; 98:785-802. [PMID: 32687732 DOI: 10.1139/cjpp-2020-0197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the primary sensory neuron, ouabain activates the dual mechanism that modulates the functional activity of NaV1.8 channels. Ouabain at endogenous concentrations (EO) triggers two different signaling cascades, in which the Na,K-ATPase/Src complex is the EO target and the signal transducer. The fast EO effect is based on modulation of the NaV1.8 channel activation gating device. EO triggers the tangential signaling cascade along the neuron membrane from Na,K-ATPase to the NaV1.8 channel. It evokes a decrease in effective charge transfer of the NaV1.8 channel activation gating device. Intracellular application of PP2, an inhibitor of Src kinase, completely eliminated the effect of EO, thus indicating the absence of direct EO binding to the NaV1.8 channel. The delayed EO effect probably controls the density of NaV1.8 channels in the neuron membrane. EO triggers the downstream signaling cascade to the neuron genome, which should result in a delayed decrease in the NaV1.8 channels' density. PKC and p38 MAPK are involved in this pathway. Identification of the dual mechanism of the strong EO effect on NaV1.8 channels makes it possible to suggest that application of EO to the primary sensory neuron membrane should result in a potent antinociceptive effect at the organismal level.
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Affiliation(s)
- Vera B Plakhova
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Makarova Emb., 199034, Saint Petersburg, Russia
| | - Valentina A Penniyaynen
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Makarova Emb., 199034, Saint Petersburg, Russia
| | - Ilia V Rogachevskii
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Makarova Emb., 199034, Saint Petersburg, Russia
| | - Svetlana A Podzorova
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Makarova Emb., 199034, Saint Petersburg, Russia
| | - Maksim M Khalisov
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Makarova Emb., 199034, Saint Petersburg, Russia
| | - Alexander V Ankudinov
- Ioffe Physical Technical Institute, Russian Academy of Sciences, 26 Polytekhnicheskaya str., 194021, Saint Petersburg, Russia
| | - Boris V Krylov
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Makarova Emb., 199034, Saint Petersburg, Russia
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30
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Abstract
Neuropathic pain caused by a lesion or disease of the somatosensory nervous system is a common chronic pain condition with major impact on quality of life. Examples include trigeminal neuralgia, painful polyneuropathy, postherpetic neuralgia, and central poststroke pain. Most patients complain of an ongoing or intermittent spontaneous pain of, for example, burning, pricking, squeezing quality, which may be accompanied by evoked pain, particular to light touch and cold. Ectopic activity in, for example, nerve-end neuroma, compressed nerves or nerve roots, dorsal root ganglia, and the thalamus may in different conditions underlie the spontaneous pain. Evoked pain may spread to neighboring areas, and the underlying pathophysiology involves peripheral and central sensitization. Maladaptive structural changes and a number of cell-cell interactions and molecular signaling underlie the sensitization of nociceptive pathways. These include alteration in ion channels, activation of immune cells, glial-derived mediators, and epigenetic regulation. The major classes of therapeutics include drugs acting on α2δ subunits of calcium channels, sodium channels, and descending modulatory inhibitory pathways.
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Affiliation(s)
- Nanna Brix Finnerup
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Neurology, Aarhus University Hospital, Aarhus, Denmark; and Department of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Rohini Kuner
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Neurology, Aarhus University Hospital, Aarhus, Denmark; and Department of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Troels Staehelin Jensen
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Neurology, Aarhus University Hospital, Aarhus, Denmark; and Department of Pharmacology, Heidelberg University, Heidelberg, Germany
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31
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Mason ER, Cummins TR. Differential Inhibition of Human Nav1.2 Resurgent and Persistent Sodium Currents by Cannabidiol and GS967. Int J Mol Sci 2020; 21:ijms21072454. [PMID: 32244818 PMCID: PMC7177867 DOI: 10.3390/ijms21072454] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/27/2020] [Accepted: 03/28/2020] [Indexed: 12/24/2022] Open
Abstract
Many epilepsy patients are refractory to conventional antiepileptic drugs. Resurgent and persistent currents can be enhanced by epilepsy mutations in the Nav1.2 channel, but conventional antiepileptic drugs inhibit normal transient currents through these channels, along with aberrant resurgent and persistent currents that are enhanced by Nav1.2 epilepsy mutations. Pharmacotherapies that specifically target aberrant resurgent and/or persistent currents would likely have fewer unwanted side effects and be effective in many patients with refractory epilepsy. This study investigated the effects of cannbidiol (CBD) and GS967 (each at 1 μM) on transient, resurgent, and persistent currents in human embryonic kidney (HEK) cells stably expressing wild-type hNav1.2 channels. We found that CBD preferentially inhibits resurgent currents over transient currents in this paradigm; and that GS967 preferentially inhibits persistent currents over transient currents. Therefore, CBD and GS967 may represent a new class of more targeted and effective antiepileptic drugs.
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Affiliation(s)
- Emily R. Mason
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, IUPUI campus, Indianapolis, IN 46202, USA
- Correspondence:
| | - Theodore R. Cummins
- Department of Biology, Purdue School of Science, IUPUI campus, Indianapolis, IN 46202, USA;
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32
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Yin K, Deuis JR, Dekan Z, Jin AH, Alewood PF, King GF, Herzig V, Vetter I. Addition of K22 Converts Spider Venom Peptide Pme2a from an Activator to an Inhibitor of Na V1.7. Biomedicines 2020; 8:biomedicines8020037. [PMID: 32092883 PMCID: PMC7167818 DOI: 10.3390/biomedicines8020037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/13/2020] [Accepted: 02/17/2020] [Indexed: 02/07/2023] Open
Abstract
Spider venom is a novel source of disulfide-rich peptides with potent and selective activity at voltage-gated sodium channels (NaV). Here, we describe the discovery of μ-theraphotoxin-Pme1a and μ/δ-theraphotoxin-Pme2a, two novel peptides from the venom of the Gooty Ornamental tarantula Poecilotheria metallica that modulate NaV channels. Pme1a is a 35 residue peptide that inhibits NaV1.7 peak current (IC50 334 ± 114 nM) and shifts the voltage dependence of activation to more depolarised membrane potentials (V1/2 activation: Δ = +11.6 mV). Pme2a is a 33 residue peptide that delays fast inactivation and inhibits NaV1.7 peak current (EC50 > 10 μM). Synthesis of a [+22K]Pme2a analogue increased potency at NaV1.7 (IC50 5.6 ± 1.1 μM) and removed the effect of the native peptide on fast inactivation, indicating that a lysine at position 22 (Pme2a numbering) is important for inhibitory activity. Results from this study may be used to guide the rational design of spider venom-derived peptides with improved potency and selectivity at NaV channels in the future.
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Affiliation(s)
- Kathleen Yin
- Centre for Health Informatics, Australian Institute of Health Innovation, Macquarie University, North Ryde, NSW 2109, Australia;
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
| | - Jennifer R. Deuis
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
| | - Zoltan Dekan
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
| | - Ai-Hua Jin
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
| | - Paul F. Alewood
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
| | - Glenn F. King
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
| | - Volker Herzig
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
- School of Science & Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia
- Correspondence: (V.H.); (I.V.); Tel.: +61-7-5456-5382 (V.H.); +61-7-3346-2660 (I.V.)
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.R.D.); (Z.D.); (P.F.A.); (G.F.K.)
- School of Pharmacy, The University of Queensland, Woolloongabba, QLD 4102, Australia
- Correspondence: (V.H.); (I.V.); Tel.: +61-7-5456-5382 (V.H.); +61-7-3346-2660 (I.V.)
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Li N, Liu B, Wu W, Hong Y, Zhang J, Liu Y, Zhang M, Zhang X, Duan G. Upregulation of transcription factor 4 downregulates Na V1.8 expression in DRG neurons and prevents the development of rat inflammatory and neuropathic hypersensitivity. Exp Neurol 2020; 327:113240. [PMID: 32045596 DOI: 10.1016/j.expneurol.2020.113240] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/20/2020] [Accepted: 02/07/2020] [Indexed: 10/25/2022]
Abstract
The voltage sodium channel 1.8 (NaV1.8) in the dorsal root ganglion (DRG) neurons contributes to the initiation and development of chronic inflammatory and neuropathic pain. However, an effective intervention on NaV1.8 remains to be studied in pre-clinical research and clinical trials. In this study, we aimed to investigate whether transcription factor 4 (TCF4) overexpression represses NaV1.8 expression in DRG neurons, thus preventing the development of chronic pain. Using chromatin immunoprecipitation (CHIP), we verified the interaction of TCF4 and sodium voltage-gated channel alpha subunit 10A (SCN10A) enhancer in HEK293 cells and rat DRG neurons. Using a dual luciferase reporter assay, we confirmed the transcriptional inhibition of TCF4 on SCN10A promoter in vitro. To investigate the regulation of TCF4 on Nav1.8, we then upregulated TCF4 expression by intrathecally delivering an overexpression of recombinant adeno-associated virus (rAAV) in the Complete Freund's adjuvant (CFA)-induced inflammatory pain model and spared nerve injury (SNI)-induced neuropathic pain model. By using a quantitative polymerase chain reaction (qPCR), western blot, and immunostaining, we evaluated NaV1.8 expression after a noxious stimulation and the application of the TCF4 overexpression virus. We showed that the intrathecal delivery of TCF4 overexpression virus significantly repressed the increase of NaV1.8 and prevented the development of hyperalgesia in rats. Moreover, we confirmed the efficient role of an overexpressed TCF4 in preventing the CFA- and SNI-induced neuronal hyperexcitability by calcium imaging. Our results suggest that attenuating the dysregulation of NaV1.8 by targeting TCF4 may be a novel therapeutic strategy for chronic inflammatory and neuropathic pain.
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Affiliation(s)
- Ningbo Li
- Department of Anesthesiology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China.; Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Baowen Liu
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Wenyao Wu
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yishun Hong
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jin Zhang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yi Liu
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Mi Zhang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xianwei Zhang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China..
| | - Guangyou Duan
- Department of Anesthesiology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China..
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Pan Y, Cummins TR. Distinct functional alterations in SCN8A epilepsy mutant channels. J Physiol 2020; 598:381-401. [PMID: 31715021 PMCID: PMC7216308 DOI: 10.1113/jp278952] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/12/2019] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Mutations in the SCN8A gene cause early infantile epileptic encephalopathy. We characterize a new epilepsy-related SCN8A mutation, R850Q, in the human SCN8A channel and present gain-of-function properties of the mutant channel. Systematic comparison of R850Q with three other SCN8A epilepsy mutations, T761I, R1617Q and R1872Q, identifies one common dysfunction in resurgent current, although these mutations alter distinct properties of the channel. Computational simulations in two different neuron models predict an increased excitability of neurons carrying these mutations, which explains the over-excitation that underlies seizure activities in patients. These data provide further insight into the mechanism of SCN8A-related epilepsy and reveal subtle but potentially important distinction of functional characterization performed in the human vs. rodent channels. ABSTRACT SCN8A is a novel causal gene for early infantile epileptic encephalopathy. It is well accepted that gain-of-function mutations in SCN8A underlie the disorder, although the remarkable heterogeneity of its clinical presentation and poor treatment response demand a better understanding of the disease mechanisms. Here, we characterize a new epilepsy-related SCN8A mutation, R850Q, in human Nav1.6. We show that it is a gain-of-function mutation, with a hyperpolarizing shift in voltage dependence of activation, a two-fold increase of persistent current and a slowed decay of resurgent current. We systematically compare its biophysics with three other SCN8A epilepsy mutations, T767I, R1617Q and R1872Q, in the human Nav1.6 channel. Although all of these mutations are gain-of-function, the mutations affect different aspects of channel properties. One commonality that we discovered is an alteration of resurgent current kinetics, although the mechanisms by which resurgent currents are augmented remain unclear for all of the mutations. Computational simulations predict an increased excitability of neurons carrying these mutations with differential enhancement by open channel blockade.
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Affiliation(s)
- Yanling Pan
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, IN, USA
| | - Theodore R Cummins
- Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, IN, USA
- Department of Biology, School of Science, IUPUI, IN, USA
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Mason ER, Wu F, Patel RR, Xiao Y, Cannon SC, Cummins TR. Resurgent and Gating Pore Currents Induced by De Novo SCN2A Epilepsy Mutations. eNeuro 2019; 6:ENEURO.0141-19.2019. [PMID: 31558572 PMCID: PMC6795554 DOI: 10.1523/eneuro.0141-19.2019] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 09/12/2019] [Accepted: 09/16/2019] [Indexed: 12/31/2022] Open
Abstract
Over 150 mutations in the SCN2A gene, which encodes the neuronal Nav1.2 protein, have been implicated in human epilepsy cases. Of these, R1882Q and R853Q are two of the most commonly reported mutations. This study utilized voltage-clamp electrophysiology to characterize the biophysical effects of the R1882Q and R853Q mutations on the hNav1.2 channel, including their effects on resurgent current and gating pore current, which are not typically investigated in the study of Nav1.2 channel mutations. HEK cells transiently transfected with DNA encoding either wild-type (WT) or mutant hNav1.2 revealed that the R1882Q mutation induced a gain-of-function phenotype, including slowed fast inactivation, depolarization of the voltage dependence of inactivation, and increased persistent current. In this model system, the R853Q mutation primarily produced loss-of-function effects, including reduced transient current amplitude and density, hyperpolarization of the voltage dependence of inactivation, and decreased persistent current. The presence of a Navβ4 peptide (KKLITFILKKTREK-OH) in the pipette solution induced resurgent currents, which were increased by the R1882Q mutation and decreased by the R853Q mutation. Further study of the R853Q mutation in Xenopus oocytes indicated a reduced surface expression and revealed a robust gating pore current at negative membrane potentials, a function absent in the WT channel. This not only shows that different epileptogenic point mutations in hNav1.2 have distinct biophysical effects on the channel, but also illustrates that individual mutations can have complex consequences that are difficult to identify using conventional analyses. Distinct mutations may, therefore, require tailored pharmacotherapies in order to eliminate seizures.
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Affiliation(s)
- Emily R Mason
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Fenfen Wu
- Department of Physiology, David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, CA 90095-1751
| | - Reesha R Patel
- Program in Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Yucheng Xiao
- School of Science, Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
| | - Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, CA 90095-1751
| | - Theodore R Cummins
- School of Science, Biology Department Chair, Indiana University-Purdue University of Indianapolis, Indianapolis, IN 46202
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Small-fiber neuropathy definition, diagnosis, and treatment. Neurol Sci 2019; 40:1343-1350. [PMID: 30968230 DOI: 10.1007/s10072-019-03871-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 03/23/2019] [Indexed: 12/13/2022]
Abstract
In the last 30 years, improvement of diagnostic methods enabled routine evaluation of small A-delta and C nerve fibers impairment, which results with the clinical condition known as a small-fiber neuropathy (SFN). This syndrome develops as a result of metabolic, toxic, immune-mediated, or genetic factors. The main clinical features include neuropathic pain and autonomic disturbance, which are occasionally disclaimed due to outstanding fatigue, daily performance decline, anxiety, and depression. As clinical, neurological, nerve conduction, and electromyography studies are commonly normal, diagnosis often depends on the finding of decreased intra-epidermal density of nerve fibers, per skin biopsy. This review highlights the etiology, clinical, diagnostic aspects, and SFN treatment.
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