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Wang K, Shen Z, Peng X, Wu X, Mao L. Circular RNA-GRIN2B Suppresses Neuropathic Pain by Targeting the NF-κB/SLICK Pathway. Neuromolecular Med 2024; 26:12. [PMID: 38600344 DOI: 10.1007/s12017-024-08774-5] [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: 01/10/2024] [Accepted: 02/21/2024] [Indexed: 04/12/2024]
Abstract
The role of circular RNAs (circRNAs) in neuropathic pain is linked to the fundamental physiological mechanisms involved. However, the exact function of circRNAs in the context of neuropathic pain is still not fully understood. The functional impact of circGRIN2B on the excitability of dorsal root ganglion (DRG) neurons was investigated using siRNA or overexpression technology in conjunction with fluorescence in situ hybridization and whole-cell patch-clamp technology. The therapeutic efficacy of circGRIN2B in treating neuropathic pain was confirmed by assessing the pain threshold in a chronic constrictive injury (CCI) model. The interaction between circGRIN2B and NF-κB was examined through RNA pulldown, RIP, and mass spectrometry assays. CircGRIN2B knockdown significantly affected the action potential discharge frequency and the sodium-dependent potassium current flux (SLICK) in DRG neurons. Furthermore, knockdown of circGRIN2B dramatically reduced the SLICK channel protein and mRNA expression in vivo and in vitro. Our research confirmed the interaction between circGRIN2B and NF-κB. These findings demonstrated that circGRIN2B promotes the transcription of the SLICK gene by binding to NF-κB. In CCI rat models, the overexpression of circGRIN2B has been shown to hinder the progression of neuropathic pain, particularly by reducing mechanical and thermal hyperalgesia. Additionally, this upregulation significantly diminished the levels of the inflammatory cytokines IL-1β, IL-6, and TNF-α in the DRG. Upon reviewing these findings, it was determined that circGRIN2B may mitigate the onset of neuropathic pain by modulating the NF-κB/SLICK pathway.
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Affiliation(s)
- Kun Wang
- Department of Orthopedics, Zhongda Hospital, Southeast University, Nanjing, China
- Medical School of Southeast University, Nanjing, China
- School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, China
| | - Zicong Shen
- Medical School of Southeast University, Nanjing, China
| | - Xin Peng
- Medical School of Southeast University, Nanjing, China
| | - Xiaotao Wu
- Department of Orthopedics, Zhongda Hospital, Southeast University, Nanjing, China.
- Medical School of Southeast University, Nanjing, China.
| | - Lu Mao
- Department of Orthopedics, Zhongda Hospital, Southeast University, Nanjing, China.
- Medical School of Southeast University, Nanjing, China.
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Cui F, Wulan T, Zhang Q, Zhang VW, Jiang Y. Identification of a novel KCNT2 variant in a family with developmental and epileptic encephalopathies: a case report and literature review. Front Genet 2024; 15:1371282. [PMID: 38510274 PMCID: PMC10951377 DOI: 10.3389/fgene.2024.1371282] [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: 01/16/2024] [Accepted: 02/20/2024] [Indexed: 03/22/2024] Open
Abstract
Background: Developmental and epileptic encephalopathies (DEEs) are a group of heterogeneous neurodevelopmental diseases characterized mainly by developmental delay/intellectual disability and early-onset epilepsy. Researchers have identified variations in the KCNT2 gene (OMIM* 610044) as the cause of DEE type 57 (MIM# 617771). Case presentation: We report in this study a 46-year-old woman who presented with early-onset epilepsy, intellectual disability, hypertrichosis, coarse facial features, and short stature. Besides, there were four other affected individuals in her family history, including two elder brothers, a younger brother, and their mother. We collected blood samples from the proband, her two affected brothers, and her clinically normal daughter for genetic analysis. Clinical exome sequencing revealed a novel heterozygous variant in the KCNT2 gene (NM_198503: c.188G>A, p.Arg63His) in the proband and her two affected brothers, while her daughter did not carry this variant. Furthermore, we reviewed all 25 patients identified in the literature with KCNT2 variants and compared their phenotypes. Conclusion: Epilepsy and intellectual disability/developmental delay occur in almost all patients with KCNT2 variants. KCNT2-relevant DEEs partially overlap with the clinical phenotypes of KATP channel diseases, particularly in hypertrichosis and distinctive coarse facial features.
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Affiliation(s)
- Fengji Cui
- Department of Molecular Genetics, Chifeng Maternity Hospital, Chifeng, China
| | - Tuoya Wulan
- Department of Reproduction, Chifeng Maternity Hospital, Chifeng, China
| | | | | | - Yuhua Jiang
- Department of Obstetrics, Chifeng Maternity Hospital, Chifeng, China
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Liu R, Sun L, Shi X, Li C, Guo X, Wang Y, Wang X, Zhang K, Wang Y, Wang Q, Wu J. Increased Expression of K Na1.2 Channel by MAPK Pathway Regulates Neuronal Activity Following Traumatic Brain Injury. Neurochem Res 2024; 49:427-440. [PMID: 37875713 DOI: 10.1007/s11064-023-04044-1] [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: 02/05/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/26/2023]
Abstract
Recent studies have indicated that functional abnormalities in the KNa1.2 channel are linked to epileptic encephalopathies. However, the role of KNa1.2 channel in traumatic brain injury (TBI) remains limited. We collected brain tissue from the TBI mice and patients with post-traumatic epilepsy (PTE) to determine changes in KNa1.2 channel following TBI. We also investigated whether the MAPK pathway, which was activated by the released cytokines after injury, regulated KNa1.2 channel in in vitro. Finally, to elucidate the physiological significance of KNa1.2 channel in neuronal excitability, we utilized the null mutant-Kcnt2-/- mice and compared their behavior patterns, seizure susceptibility, and neuronal firing properties to wild type (WT) mice. TBI was induced in both Kcnt2-/- and WT mice to investigate any differences between the two groups under pathological condition. Our findings revealed that the expression of KNa1.2 channel was notably increased only during the acute phase following TBI, while no significant elevation was observed during the late phase. Furthermore, we identified the released cytokines and activated MAPK pathway in the neurons after TBI and confirmed that KNa1.2 channel was enhanced by the MAPK pathway via stimulation of TNF-α. Subsequently, compared to WT mice, neurons from Kcnt2-/- mice showed increased neuronal excitability and Kcnt2-/- mice displayed motor deficits and enhanced seizure susceptibility, which suggested that KNa1.2 channel may be neuroprotective. Therefore, this study suggests that enhanced KNa1.2 channel, facilitated by the inflammatory response, may exert a protective role in an acute phase of the TBI model.
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Affiliation(s)
- Ru Liu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
| | - Lei Sun
- Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, 450008, Henan, China
| | - Xiaorui Shi
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Ci Li
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Xi Guo
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
| | - Yingting Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Xiu Wang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Kai Zhang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Yongjun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
| | - Qun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
- Beijing Institute for Brain Disorders, Beijing, 100070, China
| | - Jianping Wu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China.
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China.
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China.
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Cioclu MC, Mosca I, Ambrosino P, Puzo D, Bayat A, Wortmann SB, Koch J, Strehlow V, Shirai K, Matsumoto N, Sanders SJ, Michaud V, Legendre M, Riva A, Striano P, Muhle H, Pendziwiat M, Lesca G, Mangano GD, Nardello R, Lemke JR, Møller RS, Soldovieri MV, Rubboli G, Taglialatela M. KCNT2-Related Disorders: Phenotypes, Functional, and Pharmacological Properties. Ann Neurol 2023; 94:332-349. [PMID: 37062836 DOI: 10.1002/ana.26662] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 04/10/2023] [Accepted: 04/14/2023] [Indexed: 04/18/2023]
Abstract
OBJECTIVE Pathogenic variants in KCNT2 are rare causes of developmental epileptic encephalopathy (DEE). We herein describe the phenotypic and genetic features of patients with KCNT2-related DEE, and the in vitro functional and pharmacological properties of KCNT2 channels carrying 14 novel or previously untested variants. METHODS Twenty-five patients harboring KCNT2 variants were investigated: 12 were identified through an international collaborative network, 13 were retrieved from the literature. Clinical data were collected and included in a standardized phenotyping sheet. Novel variants were detected using exome sequencing and classified using ACMG criteria. Functional and pharmacological studies were performed by whole-cell electrophysiology in HEK-293 and SH-SY5Y cells. RESULTS The phenotypic spectrum encompassed: (a) intellectual disability/developmental delay (21/22 individuals with available information), ranging from mild to severe/profound; (b) epilepsy (15/25); (c) neurological impairment, with altered muscle tone (14/22); (d) dysmorphisms (13/20). Nineteen pathogenic KCNT2 variants were found (9 new, 10 reported previously): 16 missense, 1 in-frame deletion of a single amino acid, 1 nonsense, and 1 frameshift. Among tested variants, 8 showed gain-of-function (GoF), and 6 loss-of-function (LoF) features when expressed heterologously in vitro. Quinidine and fluoxetine blocked all GoF variants, whereas loxapine and riluzole activated some LoF variants while blocking others. INTERPRETATION We expanded the phenotypic and genotypic spectrum of KCNT2-related disorders, highlighting novel genotype-phenotype associations. Pathogenic KCNT2 variants cause GoF or LoF in vitro phenotypes, and each shows a unique pharmacological profile, suggesting the need for in vitro functional and pharmacological investigation to enable targeted therapies based on the molecular phenotype. ANN NEUROL 2023;94:332-349.
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Affiliation(s)
- Maria Cristina Cioclu
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Biomedical, Metabolic, and Neural Science, University of Modena and Reggio Emilia, Modena, Italy
| | - Ilaria Mosca
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Paolo Ambrosino
- Dept. of Science and Technology, University of Sannio, Benevento, Italy
| | - Deborah Puzo
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Saskia B Wortmann
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
- Amalia Children's Hospital, Nijmegen, The Netherlands
| | - Johannes Koch
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
| | - Vincent Strehlow
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Kentaro Shirai
- Department of Pediatrics, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Stephan J Sanders
- Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California, San Francisco, CA, USA
- Institute for Human Genetics, University of California, San Francisco, CA, USA
- Bakar Computational Health Sciences Institute, University of California, San Francisco, CA, USA
| | - Vincent Michaud
- Service de Génétique Médicale, Centre de Référence Anomalies du Développement et Syndrome Malformatifs, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Maladies rares: Génétique et Métabolisme (MRGM), INSERM U1211, Université de Bordeaux, Bordeaux, France
| | - Marine Legendre
- Service de Génétique Médicale, Centre de Référence Anomalies du Développement et Syndrome Malformatifs, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
| | - Antonella Riva
- IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Pasquale Striano
- IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Hiltrud Muhle
- Department of Neuropediatrics, University Medical Centre Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Manuela Pendziwiat
- Department of Neuropediatrics, University Medical Centre Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Gaetan Lesca
- Pathophysiology and Genetics of Neuron and Muscle (PNMG), UCBL, CNRS UMR5261-INSERM U1315, Lyon, France
- Department of Medical Genetics, University Hospital of Lyon and Claude Bernard Lyon I University, Lyon, France
| | - Giuseppe Donato Mangano
- Department of Biomedicine, Neuroscience and Advanced Diagnostics, University of Palermo, Palermo, Italy
| | - Rosaria Nardello
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Maria Virginia Soldovieri
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Guido Rubboli
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- University of Copenhagen, Copenhagen, Denmark
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Slick Potassium Channels Control Pain and Itch in Distinct Populations of Sensory and Spinal Neurons in Mice. Anesthesiology 2022; 136:802-822. [PMID: 35303056 DOI: 10.1097/aln.0000000000004163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Slick, a sodium-activated potassium channel, has been recently identified in somatosensory pathways, but its functional role is poorly understood. The authors of this study hypothesized that Slick is involved in processing sensations of pain and itch. METHODS Immunostaining, in situ hybridization, Western blot, and real-time quantitative reverse transcription polymerase chain reaction were used to investigate the expression of Slick in dorsal root ganglia and the spinal cord. Mice lacking Slick globally (Slick-/-) or conditionally in neurons of the spinal dorsal horn (Lbx1-Slick-/-) were assessed in behavioral models. RESULTS The authors found Slick to be enriched in nociceptive Aδ-fibers and in populations of interneurons in the spinal dorsal horn. Slick-/- mice, but not Lbx1-Slick-/- mice, showed enhanced responses to noxious heat in the hot plate and tail-immersion tests. Both Slick-/- and Lbx1-Slick-/- mice demonstrated prolonged paw licking after capsaicin injection (mean ± SD, 45.6 ± 30.1 s [95% CI, 19.8 to 71.4]; and 13.1 ± 16.1 s [95% CI, 1.8 to 28.0]; P = 0.006 [Slick-/- {n = 8} and wild-type {n = 7}, respectively]), which was paralleled by increased phosphorylation of the neuronal activity marker extracellular signal-regulated kinase in the spinal cord. In the spinal dorsal horn, Slick is colocalized with somatostatin receptor 2 (SSTR2), and intrathecal preadministration of the SSTR2 antagonist CYN-154806 prevented increased capsaicin-induced licking in Slick-/- and Lbx1-Slick-/- mice. Moreover, scratching after intrathecal delivery of the somatostatin analog octreotide was considerably reduced in Slick-/- and Lbx1-Slick-/- mice (Slick-/- [n = 8]: 6.1 ± 6.7 bouts [95% CI, 0.6 to 11.7]; wild-type [n =8]: 47.4 ± 51.1 bouts [95% CI, 4.8 to 90.2]; P = 0.039). CONCLUSIONS Slick expressed in a subset of sensory neurons modulates heat-induced pain, while Slick expressed in spinal cord interneurons inhibits capsaicin-induced pain but facilitates somatostatin-induced itch. EDITOR’S PERSPECTIVE
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Slo2/K Na Channels in Drosophila Protect against Spontaneous and Induced Seizure-like Behavior Associated with an Increased Persistent Na + Current. J Neurosci 2021; 41:9047-9063. [PMID: 34544836 DOI: 10.1523/jneurosci.0290-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/20/2021] [Accepted: 09/13/2021] [Indexed: 11/21/2022] Open
Abstract
Na+ sensitivity is a unique feature of Na+-activated K+ (KNa) channels, making them naturally suited to counter a sudden influx in Na+ ions. As such, it has long been suggested that KNa channels may serve a protective function against excessive excitation associated with neuronal injury and disease. This hypothesis, however, has remained largely untested. Here, we examine KNa channels encoded by the Drosophila Slo2 (dSlo2) gene in males and females. We show that dSlo2/KNa channels are selectively expressed in cholinergic neurons in the adult brain, as well as in glutamatergic motor neurons, where dampening excitation may function to inhibit global hyperactivity and seizure-like behavior. Indeed, we show that effects of feeding Drosophila a cholinergic agonist are exacerbated by the loss of dSlo2/KNa channels. Similar to mammalian Slo2/KNa channels, we show that dSlo2/KNa channels encode a TTX-sensitive K+ conductance, indicating that dSlo2/KNa channels can be activated by Na+ carried by voltage-dependent Na+ channels. We then tested the role of dSlo2/KNa channels in established genetic seizure models in which the voltage-dependent persistent Na+ current (INap) is elevated. We show that the absence of dSlo2/KNa channels increased susceptibility to mechanically induced seizure-like behavior. Similar results were observed in WT flies treated with veratridine, an enhancer of INap Finally, we show that loss of dSlo2/KNa channels in both genetic and pharmacologically primed seizure models resulted in the appearance of spontaneous seizures. Together, our results support a model in which dSlo2/KNa channels, activated by neuronal overexcitation, contribute to a protective threshold to suppress the induction of seizure-like activity.SIGNIFICANCE STATEMENT Slo2/KNa channels are unique in that they constitute a repolarizing K+ pore that is activated by the depolarizing Na+ ion, making them naturally suited to function as a protective "brake" against overexcitation and Na+ overload. Here, we test this hypothesis in vivo by examining how a null mutation of the Drosophila Slo2 (dSlo2)/KNa gene affects seizure-like behavior in genetic and pharmacological models of epilepsy. We show that indeed the loss of dSlo2/KNa channels results in increased incidence and severity of induced seizure behavior, as well as the appearance of spontaneous seizure activity. Our results advance our understanding of neuronal excitability and protective mechanisms that preserve normal physiology and the suppression of seizure susceptibility.
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Inhibiting endocytosis in CGRP + nociceptors attenuates inflammatory pain-like behavior. Nat Commun 2021; 12:5812. [PMID: 34608164 PMCID: PMC8490418 DOI: 10.1038/s41467-021-26100-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 09/06/2021] [Indexed: 12/20/2022] Open
Abstract
The advantage of locally applied anesthetics is that they are not associated with the many adverse effects, including addiction liability, of systemically administered analgesics. This therapeutic approach has two inherent pitfalls: specificity and a short duration of action. Here, we identified nociceptor endocytosis as a promising target for local, specific, and long-lasting treatment of inflammatory pain. We observed preferential expression of AP2α2, an α-subunit isoform of the AP2 complex, within CGRP+/IB4- nociceptors in rodents and in CGRP+ dorsal root ganglion neurons from a human donor. We utilized genetic and pharmacological approaches to inhibit nociceptor endocytosis demonstrating its role in the development and maintenance of acute and chronic inflammatory pain. One-time injection of an AP2 inhibitor peptide significantly reduced acute and chronic pain-like behaviors and provided prolonged analgesia. We evidenced sexually dimorphic recovery responses to this pharmacological approach highlighting the importance of sex differences in pain development and response to analgesics. The authors show the endocytotic adaptor subunit called AP2A2 is differentially expressed in CGRP+ nociceptors. Locally inhibiting nociceptor endocytosis with a lipidated AP2 inhibitor peptide reduces acute and chronic pain-like behaviour in mice and rats, indicating prolonged analgesia.
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8
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Wang S, Chung MK. Orthodontic force induces nerve injury-like transcriptomic changes driven by TRPV1-expressing afferents in mouse trigeminal ganglia. Mol Pain 2021; 16:1744806920973141. [PMID: 33215551 PMCID: PMC7686596 DOI: 10.1177/1744806920973141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Orthodontic force produces mechanical irritation and localized inflammation in
the periodontium, which causes pain in most patients. Nocifensive behaviors
resulting from orthodontic force in mice can be substantially attenuated by
intraganglionic injection of resiniferatoxin (RTX), a neurotoxin that
specifically ablates a subset of neurons expressing transient receptor potential
vanilloid 1 (TRPV1). In the current study, we determined changes in the
transcriptomic profiles in the trigeminal ganglia (TG) following the application
of orthodontic force, and assessed the roles of TRPV1-expressing afferents in
these transcriptomic changes. RTX or vehicle was injected into the TG of mice a
week before the placement of an orthodontic spring exerting 10 g of force. After
2 days, the TG were collected for RNA sequencing. The application of orthodontic
force resulted in 1279 differentially expressed genes (DEGs) in the TG. Gene
ontology analysis showed downregulation of gliogenesis and ion channel
activities, especially of voltage-gated potassium channels. DEGs produced by
orthodontic force correlated more strongly with DEGs resulting from nerve injury
than from inflammation. Orthodontic force resulted in the differential
expression of multiple genes involved in pain regulation, including upregulation
of Atf3, Adcyap1, Bdnf, and
Csf1, and downregulation of Scn10a,
Kcna2, Kcnj10, and P2ry1.
Orthodontic force-induced DEGs correlated with DEGs specific to multiple
neuronal and non-neuronal subtypes following nerve injury. These transcriptomic
changes were abolished in the mice that received the RTX injection. These
results suggest that orthodontic force produces transcriptomic changes
resembling nerve injury in the TG and that nociceptive inputs through
TRPV1-expressing afferents leads to subsequent changes in gene expression not
only in TRPV1-positive neurons, but also in TRPV1-negative neurons and
non-neuronal cells throughout the ganglia. Orthodontic force-induced
transcriptomic changes might be an active regenerative program of trigeminal
ganglia in response to axonal injury following orthodontic force.
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Affiliation(s)
- Sheng Wang
- Department of Neural and Pain Sciences, Center to Advance Chronic Pain Research, University of Maryland Dental School, Baltimore, MD, USA
| | - Man-Kyo Chung
- Department of Neural and Pain Sciences, Center to Advance Chronic Pain Research, University of Maryland Dental School, Baltimore, MD, USA
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Sheehan GD, Martin MK, Young VA, Powell R, Bhattacharjee A. Thermal hyperalgesia and dynamic weight bearing share similar recovery dynamics in a sciatic nerve entrapment injury model. NEUROBIOLOGY OF PAIN 2021; 10:100079. [PMID: 34917858 PMCID: PMC8665403 DOI: 10.1016/j.ynpai.2021.100079] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/01/2021] [Accepted: 12/01/2021] [Indexed: 11/28/2022]
Abstract
The sciatic nerve cuff model of neuropathic pain exhibits pain recovery. Thermal hyperalgesia and dynamic weight bearing display similar pain recovery profiles, whereas mechanical allodynia persists. Dynamic weight bearing is a non-reflexive, pain assessment of ongoing pain during nerve entrapment.
Chronic constriction injuries (CCI) of the sciatic nerve are widely used nerve entrapment animal models of neuropathic pain. Two common pain behaviors observed following CCI are thermal hyperalgesia and mechanical allodynia, measured by the Hargreaves and von Frey tests, respectively. While thermal hyperalgesia tends to recover by 30 days, mechanical allodynia can persist for many more months thereafter. Consequently, mechanical allodynia has been used extensively as a measure of ‘chronic pain’ focusing on the circuitry changes that occur within the spinal cord. Here, using the sciatic nerve cuff variant of CCI in mice, we propose that in contrast to these evoked measures of nociceptive hypersensitivity, dynamic weight bearing provides a more clinically relevant behavioral measure for ongoing pain during nerve injury. We found that the effect of sciatic nerve cuff on the ratio of weight bearing by the injured relative to uninjured hindlimbs more closely resembled that of thermal hyperalgesia, following a trend toward recovery by 30 days. We also found an increase in the percent of body weight bearing by the contralateral paw that is not seen in the previously tested behaviors. These results demonstrate that dynamic weight bearing is a reliable measure of non-evoked neuropathic pain and suggest that thermal hyperalgesia, rather than mechanical allodynia, provides a proxy measure for nerve entrapment-induced ongoing pain.
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Affiliation(s)
- Garrett D. Sheehan
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Molly K. Martin
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Violet A. Young
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Rasheen Powell
- Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
| | - Arin Bhattacharjee
- Program in Neuroscience, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
- Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York, Buffalo, NY 14203, USA
- Corresponding author at: Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York USA.
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10
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Jackson A, Banka S, Stewart H, Robinson H, Lovell S, Clayton-Smith J. Recurrent KCNT2 missense variants affecting p.Arg190 result in a recognizable phenotype. Am J Med Genet A 2021; 185:3083-3091. [PMID: 34061450 DOI: 10.1002/ajmg.a.62370] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/29/2021] [Accepted: 05/05/2021] [Indexed: 12/13/2022]
Abstract
KCNT2 variants resulting in substitutions affecting the Arg190 residue have been shown to cause epileptic encephalopathy and a recognizable facial gestalt. We report two additional individuals with intellectual disability, dysmorphic features, hypertrichosis, macrocephaly and the same de novo KCNT2 missense variants affecting the Arg190 residue as previously described. Notably, neither patient has epilepsy. Homology modeling of these missense variants revealed that they are likely to disrupt the stabilization of a closed channel conformation of KCNT2 resulting in a constitutively open state. This is the first report of pathogenic variants in KCNT2 causing a developmental phenotype without epilepsy.
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Affiliation(s)
- Adam Jackson
- Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Siddharth Banka
- Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Helen Stewart
- Department of Clinical Genetics, Oxford Centre for Genomic Medicine, Oxford Radcliffe Hospitals NHS Trust, Nuffield Orthopaedic Hospital, Oxford, UK
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- Genomics England, London, UK
| | - Hannah Robinson
- Department of Peninsula Clinical Genetics, Exeter Genomics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Simon Lovell
- Division of Evolution and Genomic Sciences, School of Biological Sciences, University of Manchester, Manchester, UK
| | - Jill Clayton-Smith
- Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
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11
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Canto AM, Matos AHB, Godoi AB, Vieira AS, Aoyama BB, Rocha CS, Henning B, Carvalho BS, Pascoal VDB, Veiga DFT, Gilioli R, Cendes F, Lopes-Cendes I. Multi-omics analysis suggests enhanced epileptogenesis in the Cornu Ammonis 3 of the pilocarpine model of mesial temporal lobe epilepsy. Hippocampus 2020; 31:122-139. [PMID: 33037862 DOI: 10.1002/hipo.23268] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 09/04/2020] [Accepted: 09/26/2020] [Indexed: 12/11/2022]
Abstract
Mesial temporal lobe epilepsy (MTLE) is a chronic neurological disorder characterized by the occurrence of seizures, and histopathological abnormalities in the mesial temporal lobe structures, mainly hippocampal sclerosis (HS). We used a multi-omics approach to determine the profile of transcript and protein expression in the dorsal and ventral hippocampal dentate gyrus (DG) and Cornu Ammonis 3 (CA3) in an animal model of MTLE induced by pilocarpine. We performed label-free proteomics and RNAseq from laser-microdissected tissue isolated from pilocarpine-induced Wistar rats. We divided the DG and CA3 into dorsal and ventral areas and analyzed them separately. We performed a data integration analysis and evaluated enriched signaling pathways, as well as the integrated networks generated based on the gene ontology processes. Our results indicate differences in the transcriptomic and proteomic profiles among the DG and the CA3 subfields of the hippocampus. Moreover, our data suggest that epileptogenesis is enhanced in the CA3 region when compared to the DG, with most abnormalities in transcript and protein levels occurring in the CA3. Furthermore, our results show that the epileptogenesis in the pilocarpine model involves predominantly abnormal regulation of excitatory neuronal mechanisms mediated by N-methyl D-aspartate (NMDA) receptors, changes in the serotonin signaling, and neuronal activity controlled by calcium/calmodulin-dependent protein kinase (CaMK) regulation and leucine-rich repeat kinase 2 (LRRK2)/WNT signaling pathways.
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Affiliation(s)
- Amanda M Canto
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil
| | - Alexandre H B Matos
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil
| | - Alexandre B Godoi
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil
| | - André S Vieira
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil.,Department of Structural and Functional Biology, Institute of Biology. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Beatriz B Aoyama
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil.,Department of Structural and Functional Biology, Institute of Biology. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Cristiane S Rocha
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil
| | - Barbara Henning
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil
| | - Benilton S Carvalho
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil.,Department of Statistics, Institute of Mathematics, Statistics and Scientific Computing. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Vinicius D B Pascoal
- Department of Basic Sciences, Fluminense Federal University (UFF), Nova Friburgo, Rio de Janeiroz, Brazil
| | - Diogo F T Veiga
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA
| | - Rovilson Gilioli
- Laboratory of Animal Quality Control, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Fernando Cendes
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil.,Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Iscia Lopes-Cendes
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, São Paulo, Brazil
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12
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Amador-Muñoz D, Gutiérrez ÁM, Payán-Gómez C, Matheus LM. In silico and in vitro analysis of cation-activated potassium channels in human corneal endothelial cells. Exp Eye Res 2020; 197:108114. [PMID: 32561484 DOI: 10.1016/j.exer.2020.108114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/02/2020] [Accepted: 06/07/2020] [Indexed: 12/31/2022]
Abstract
The corneal endothelium is the inner cell monolayer involved in the maintenance of corneal transparence by the generation of homeostatic dehydration. The glycosaminoglycans of the corneal stroma develop a continuous swelling pressure that should be counteracted by the corneal endothelial cells through active transport mechanisms to move the water to the anterior chamber. Protein transporters for sodium (Na+), potassium (K+), chloride (Cl-) and bicarbonate (HCO3-) are involved in this endothelial "pump function", however despite its physiological importance, the efflux mechanism is not completely understood. There is experimental evidence describing transendothelial diffusion of water in the absence of osmotic gradients. Therefore, it is important to get a deeper understanding of alternative models that drive the fluid transport across the endothelium such as the electrochemical gradients. Three transcriptomic datasets of the corneal endothelium were used in this study to analyze the expression of genes that encode proteins that participate in the transport and the reestablishment of the membrane potential across the semipermeable endothelium. Subsequently, the expression of the identified channels was validated in vitro both at mRNA and protein levels. The results of this study provide the first evidence of the expression of KCNN2, KCNN3 and KCNT2 genes in the corneal endothelium. Differences among the level of expression of KCNN2, KCNT2 and KCNN4 genes were found in a differentially expressed gene analysis of the dataset. Taken together these results underscore the potential importance of the ionic channels in the pathophysiology of corneal diseases. Moreover, we elucidate novel mechanisms that might be involved in the pivotal dehydrating function of the endothelium and in others physiologic functions of these cells using in silico pathways analysis.
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Affiliation(s)
- Diana Amador-Muñoz
- Neuroscience (NEUROS) Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 No. 63 C 69, P.O 111221, Bogotá, Colombia.
| | - Ángela María Gutiérrez
- Escuela Superior de Oftalmología, Instituto Barraquer de América, Calle 100 No. 18 A 51, Bogotá, Colombia.
| | - César Payán-Gómez
- Department of Biology, Faculty of Natural Sciences, Universidad del Rosario, Carrera 24 No. 63 C 69, Bogotá, P.O 111221, Colombia.
| | - Luisa Marina Matheus
- Neuroscience (NEUROS) Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 No. 63 C 69, P.O 111221, Bogotá, Colombia.
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13
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Lee JH, Kang M, Park S, Perez-Flores MC, Zhang XD, Wang W, Gratton MA, Chiamvimonvat N, Yamoah EN. The local translation of KNa in dendritic projections of auditory neurons and the roles of KNa in the transition from hidden to overt hearing loss. Aging (Albany NY) 2019; 11:11541-11564. [PMID: 31812952 PMCID: PMC6932877 DOI: 10.18632/aging.102553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/20/2019] [Indexed: 02/07/2023]
Abstract
Local and privileged expression of dendritic proteins allows segregation of distinct functions in a single neuron but may represent one of the underlying mechanisms for early and insidious presentation of sensory neuropathy. Tangible characteristics of early hearing loss (HL) are defined in correlation with nascent hidden hearing loss (HHL) in humans and animal models. Despite the plethora of causes of HL, only two prevailing mechanisms for HHL have been identified, and in both cases, common structural deficits are implicated in inner hair cell synapses, and demyelination of the auditory nerve (AN). We uncovered that Na+-activated K+ (KNa) mRNA and channel proteins are distinctly and locally expressed in dendritic projections of primary ANs and genetic deletion of KNa channels (Kcnt1 and Kcnt2) results in the loss of proper AN synaptic function, characterized as HHL, without structural synaptic alterations. We further demonstrate that the local functional synaptic alterations transition from HHL to increased hearing-threshold, which entails changes in global Ca2+ homeostasis, activation of caspases 3/9, impaired regulation of inositol triphosphate receptor 1 (IP3R1), and apoptosis-mediated neurodegeneration. Thus, the present study demonstrates how local synaptic dysfunction results in an apparent latent pathological phenotype (HHL) and, if undetected, can lead to overt HL. It also highlights, for the first time, that HHL can precede structural synaptic dysfunction and AN demyelination. The stepwise cellular mechanisms from HHL to canonical HL are revealed, providing a platform for intervention to prevent lasting and irreversible age-related hearing loss (ARHL).
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Affiliation(s)
- Jeong Han Lee
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Mincheol Kang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Seojin Park
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Maria C Perez-Flores
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Xiao-Dong Zhang
- Department of Internal Medicine, Division of Cardiology, University of California Davis, Davis, CA 95616, USA
| | - Wenying Wang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Michael Anne Gratton
- Department of Otolaryngology, Head and Neck Surgery, Washington University St. Louis, St. Louis, MO 63110, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiology, University of California Davis, Davis, CA 95616, USA
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
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14
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Sandercock DA, Barnett MW, Coe JE, Downing AC, Nirmal AJ, Di Giminiani P, Edwards SA, Freeman TC. Transcriptomics Analysis of Porcine Caudal Dorsal Root Ganglia in Tail Amputated Pigs Shows Long-Term Effects on Many Pain-Associated Genes. Front Vet Sci 2019; 6:314. [PMID: 31620455 PMCID: PMC6760028 DOI: 10.3389/fvets.2019.00314] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 09/03/2019] [Indexed: 12/24/2022] Open
Abstract
Tail amputation by tail docking or as an extreme consequence of tail biting in commercial pig production potentially has serious implications for animal welfare. Tail amputation causes peripheral nerve injury that might be associated with lasting chronic pain. The aim of this study was to investigate the short- and long-term effects of tail amputation in pigs on caudal DRG gene expression at different stages of development, particularly in relation to genes associated with nociception and pain. Microarrays were used to analyse whole DRG transcriptomes from tail amputated and sham-treated pigs 1, 8, and 16 weeks following tail treatment at either 3 or 63 days of age (8 pigs/treatment/age/time after treatment; n = 96). Tail amputation induced marked changes in gene expression (up and down) compared to sham-treated intact controls for all treatment ages and time points after tail treatment. Sustained changes in gene expression in tail amputated pigs were still evident 4 months after tail injury. Gene correlation network analysis revealed two co-expression clusters associated with amputation: Cluster A (759 down-regulated) and Cluster B (273 up-regulated) genes. Gene ontology (GO) enrichment analysis identified 124 genes in Cluster A and 61 genes in Cluster B associated with both “inflammatory pain” and “neuropathic pain.” In Cluster A, gene family members of ion channels e.g., voltage-gated potassium channels (VGPC) and receptors e.g., GABA receptors, were significantly down-regulated compared to shams, both of which are linked to increased peripheral nerve excitability after axotomy. Up-regulated gene families in Cluster B were linked to transcriptional regulation, inflammation, tissue remodeling, and regulatory neuropeptide activity. These findings, demonstrate that tail amputation causes sustained transcriptomic expression changes in caudal DRG cells involved in inflammatory and neuropathic pain pathways.
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Affiliation(s)
- Dale A Sandercock
- Animal and Veterinary Science Research Group, Scotland's Rural College, Roslin Institute Building, Edinburgh, United Kingdom
| | - Mark W Barnett
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Jennifer E Coe
- Animal and Veterinary Science Research Group, Scotland's Rural College, Roslin Institute Building, Edinburgh, United Kingdom
| | - Alison C Downing
- Edinburgh Genomics, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ajit J Nirmal
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Pierpaolo Di Giminiani
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Sandra A Edwards
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Tom C Freeman
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
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15
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Sodium-activated potassium channels shape peripheral auditory function and activity of the primary auditory neurons in mice. Sci Rep 2019; 9:2573. [PMID: 30796290 PMCID: PMC6384918 DOI: 10.1038/s41598-019-39119-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/17/2019] [Indexed: 11/08/2022] Open
Abstract
Potassium (K+) channels shape the response properties of neurons. Although enormous progress has been made to characterize K+ channels in the primary auditory neurons, the molecular identities of many of these channels and their contributions to hearing in vivo remain unknown. Using a combination of RNA sequencing and single molecule fluorescent in situ hybridization, we localized expression of transcripts encoding the sodium-activated potassium channels KNa1.1 (SLO2.2/Slack) and KNa1.2 (SLO2.1/Slick) to the primary auditory neurons (spiral ganglion neurons, SGNs). To examine the contribution of these channels to function of the SGNs in vivo, we measured auditory brainstem responses in KNa1.1/1.2 double knockout (DKO) mice. Although auditory brainstem response (wave I) thresholds were not altered, the amplitudes of suprathreshold responses were reduced in DKO mice. This reduction in amplitude occurred despite normal numbers and molecular architecture of the SGNs and their synapses with the inner hair cells. Patch clamp electrophysiology of SGNs isolated from DKO mice displayed altered membrane properties, including reduced action potential thresholds and amplitudes. These findings show that KNa1 channel activity is essential for normal cochlear function and suggest that early forms of hearing loss may result from physiological changes in the activity of the primary auditory neurons.
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