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Leonard S, Benfante R. Unanswered questions in the regulation and function of the duplicated α7 nicotinic receptor gene CHRFAM7A. Pharmacol Res 2023; 192:106783. [PMID: 37164281 DOI: 10.1016/j.phrs.2023.106783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/20/2023] [Accepted: 04/30/2023] [Indexed: 05/12/2023]
Abstract
The α7 nicotinic receptor (α7 nAChR) is an important entry point for Ca2+ into the cell, which has broad and important effects on gene expression and function. The gene (CHRNA7), mapping to chromosome (15q14), has been genetically linked to a large number of diseases, many of which involve defects in cognition. While numerous mutations in CHRNA7 are associated with mental illness and inflammation, an important control point may be the function of a recently discovered partial duplication CHRNA7, CHRFAM7A, that negatively regulates the function of the α7 receptor, through the formation of heteropentamers; other functions cannot be excluded. The deregulation of this human specific gene (CHRFAM7A) has been linked to neurodevelopmental, neurodegenerative, and inflammatory disorders and has important copy number variations. Much effort is being made to understand its function and regulation both in healthy and pathological conditions. However, many questions remain to be answered regarding its functional role, its regulation, and its role in the etiogenesis of neurological and inflammatory disorders. Missing knowledge on the pharmacology of the heteroreceptor has limited the discovery of new molecules capable of modulating its activity. Here we review the state of the art on the role of CHRFAM7A, highlighting unanswered questions to be addressed. A possible therapeutic approach based on genome editing protocols is also discussed.
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Affiliation(s)
- Sherry Leonard
- Department of Psychiatry - University of Colorado Anschutz, Aurora, Colorado, USA
| | - Roberta Benfante
- CNR - Institute of Neuroscience, Vedano al Lambro (MB), Italy; Dept. Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy; NeuroMI - Milan Center for Neuroscience, University of Milano Bicocca, Milan, Italy.
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2
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Physiologic Functions and Therapeutic Applications of α7 Nicotinic Acetylcholine Receptor in Brain Disorders. Pharmaceutics 2022; 15:pharmaceutics15010031. [PMID: 36678660 PMCID: PMC9865019 DOI: 10.3390/pharmaceutics15010031] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/13/2022] [Accepted: 12/17/2022] [Indexed: 12/25/2022] Open
Abstract
Accumulating data suggest that α7 nicotinic acetylcholine receptors (α7nAChRs) are an important therapeutic target for the treatment of Alzheimer's disease (AD) and schizophrenia. The homopentameric ligand-gated ion channel α7nAChR consists of five identical α7 subunits that are encoded by the CHRNA7 (cholinergic receptor nicotinic alpha7 subunit) gene. Moreover, α7nAChRs are densely distributed throughout the hippocampus, cortex, and thalamus brain regions, but sparsely in the striatum, forebrain, and medulla. Compared with other nAChRs, α7nAChR binds with low affinity to the naturally occurring neurotransmitter acetylcholine and the non-specific exogenous agonist nicotine, and with high affinity to the specific antagonists α-bungarotoxin and methyllycaconitine. Reports indicate that α7nAChR plays important roles in neurotransmitter release, cognitive functioning, and the cholinergic anti-inflammatory response. Genetic variations that alter CHRNA7 mRNA and protein expression or cause α7nAChR dysfunction are associated with many brain disorders. Our previous studies revealed that α7nAChR exerts neuroprotection in AD by acting as a cargo receptor for binding the autophagosomal marker protein LC3 and engulfing extracellular neurotoxic Aβ1-42 during autophagic degradation of the α7nAChR-Aβ1-42 complex. However, the role of α7nAChRs in other diseases remains unknown. Here, we review and summarize the essential characteristics and current findings concerning α7nAChRs in four common brain diseases (AD, Parkinson's disease, schizophrenia, and depression), which may elucidate the role of α7nAChRs and inform innovative research and novel treatments that target α7nAChRs in brain disease.
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Hammarlund ME, Darsalia V, Mjörnstedt F, Pattanaik B, Mallard C, Rocha-Ferreira E, Patrone C, Johansson M. The selective alpha7 nicotinic acetylcholine receptor agonist AR-R17779 does not affect ischemia-reperfusion brain injury in mice. Biosci Rep 2021; 41:BSR20210736. [PMID: 34008839 PMCID: PMC8200656 DOI: 10.1042/bsr20210736] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/10/2021] [Accepted: 05/17/2021] [Indexed: 12/20/2022] Open
Abstract
Inflammation plays a central role in stroke-induced brain injury. The alpha7 nicotinic acetylcholine receptor (α7nAChR) can modulate immune responses in both the periphery and the brain. The aims of the present study were to investigate α7nAChR expression in different brain regions and evaluate the potential effect of the selective α7nAChR agonist AR-R17779 on ischemia-reperfusion brain injury in mice. Droplet digital PCR (ddPCR) was used to evaluate the absolute expression of the gene encoding α7nAChR (Chrna7) in hippocampus, striatum, thalamus and cortex in adult, naïve mice. Mice subjected to transient middle cerebral artery occlusion (tMCAO) or sham surgery were treated with α7nAChR agonist AR-R17779 (12 mg/kg) or saline once daily for 5 days. Infarct size and microglial activation 7 days after tMCAO were analyzed using immunohistochemistry. Chrna7 expression was found in all analyzed brain regions in naïve mice with the highest expression in cortex and hippocampus. At sacrifice, white blood cell count was significantly decreased in AR-R17779 treated mice compared with saline controls in the sham groups, although, no effect was seen in the tMCAO groups. Brain injury and microglial activation were evident 7 days after tMCAO. However, no difference was found between mice treated with saline or AR-R17779. In conclusion, α7nAChR expression varies in different brain regions and, despite a decrease in white blood cells in sham mice receiving AR-R17779, this compound does not affect stroke-induced brain injury.
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Affiliation(s)
- Maria E. Hammarlund
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Vladimer Darsalia
- Department of Clinical Science and Education, Södersjukhuset, Internal Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Filip Mjörnstedt
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Bagmi Pattanaik
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Eridan Rocha-Ferreira
- Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Cesare Patrone
- Department of Clinical Science and Education, Södersjukhuset, Internal Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Maria E. Johansson
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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İnce B, Altinoz MA, Ayran AC, Cansız A, Altinbaş K, Guloksuz S, Kurt E. Minor Physical Anomalies in Bipolar Disorder. Compr Psychiatry 2020; 103:152206. [PMID: 33099105 DOI: 10.1016/j.comppsych.2020.152206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 06/07/2020] [Accepted: 09/01/2020] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE High-arched palate is more frequent in schizophrenia and bipolar disorder (BD). Upto 40% of patients develop schizophrenia in 22q11.2 Deletion Syndrome manifested with cleft lip and palate, which originate from the first pharyngeal arch in embryo. The auricle also originates from the dorsal ends of the first and second pharyngeal arches; hence, we aimed to determine the associations between auricular anomalies and BD. METHODS We screened for 36 minor physical anomalies of the auricle in 146 patients with BD. RESULTS 7 out of the of 36 assessed anomalies highly differed between healthy subjects and BD patients. A regression model including the differing anomalies predicted healthy subjects and BD-patients by 78.8% and 68.5%, respectively. CONCLUSIONS Assessing minor anomalies in psychiatric disorders may help to discover novel pathogenesis pathways and even new endophenotypes.
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Affiliation(s)
- Bahri İnce
- Department of Psychiatry, Bakirkoy Research and Training Hospital for Psychiatry Neurology and Neurosurgery, Istanbul, Turkey
| | - Meric A Altinoz
- Department of Psychiatry and Psychology, Maastricht University Medical Centre, Maastricht, the Netherlands; Department of Medical Biochemistry, Acibadem University, Istanbul, Turkey.
| | - Aylin Can Ayran
- Department of Psychiatry, Kilis State Hospital, Kilis, Turkey
| | - Alparslan Cansız
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Kürşat Altinbaş
- Department of Psychiatry, Faculty of Medicine, Selçuk University, Konya, Turkey
| | - Sinan Guloksuz
- Department of Psychiatry and Psychology, Maastricht University Medical Centre, Maastricht, the Netherlands; Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Erhan Kurt
- Department of Psychiatry, Bakirkoy Research and Training Hospital for Psychiatry Neurology and Neurosurgery, Istanbul, Turkey
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Nakamura Y, Kimura S, Takada N, Takemura M, Iwamoto M, Hisaoka-Nakashima K, Nakata Y, Morioka N. Stimulation of toll-like receptor 4 downregulates the expression of α7 nicotinic acetylcholine receptors via histone deacetylase in rodent microglia. Neurochem Int 2020; 138:104751. [DOI: 10.1016/j.neuint.2020.104751] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/23/2020] [Accepted: 05/03/2020] [Indexed: 12/17/2022]
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Cai X, Chang LB, Potter J, Song C. Adaptive Fisher method detects dense and sparse signals in association analysis of SNV sets. BMC Med Genomics 2020; 13:46. [PMID: 32241265 PMCID: PMC7118831 DOI: 10.1186/s12920-020-0684-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND With the development of next generation sequencing (NGS) technology and genotype imputation methods, statistical methods have been proposed to test a set of genomic variants together to detect if any of them is associated with the phenotype or disease. In practice, within the set, there is an unknown proportion of variants truly causal or associated with the disease. There is a demand for statistical methods with high power in both dense and sparse scenarios, where the proportion of causal or associated variants is large or small respectively. RESULTS We propose a new association test - weighted Adaptive Fisher (wAF) that can adapt to both dense and sparse scenarios by adding weights to the Adaptive Fisher (AF) method we developed before. Using simulation, we show that wAF enjoys comparable or better power to popular methods such as sequence kernel association tests (SKAT and SKAT-O) and adaptive SPU (aSPU) test. We apply wAF to a publicly available schizophrenia dataset, and successfully detect thirteen genes. Among them, three genes are supported by existing literature; six are plausible as they either relate to other neurological diseases or have relevant biological functions. CONCLUSIONS The proposed wAF method is a powerful disease-variants association test in both dense and sparse scenarios. Both simulation studies and real data analysis indicate the potential of wAF for new biological findings.
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Affiliation(s)
- Xiaoyu Cai
- Department of Statistics, The Ohio State University, 1948 Neil Ave., Columbus, OH 43210, US
| | - Lo-Bin Chang
- Department of Statistics, The Ohio State University, 1948 Neil Ave., Columbus, OH 43210, US
| | - Jordan Potter
- Department of Mathematics and Statistics, Kenyon College, 201 N College Rd., Gambier, Ohio 43022, US
| | - Chi Song
- College of Public Health, Division of Biostatistics, The Ohio State University, 1841 Neil Ave., 208E Cunz Hall, Columbus, OH 43210, US
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Lin MW, Chen YH, Yang HB, Lin CC, Hung SY. Galantamine Inhibits Aβ 1-42-Induced Neurotoxicity by Enhancing α7nAChR Expression as a Cargo Carrier for LC3 Binding and Aβ 1-42 Engulfment During Autophagic Degradation. Neurotherapeutics 2020; 17:676-689. [PMID: 31823156 PMCID: PMC7283419 DOI: 10.1007/s13311-019-00803-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Despite Alzheimer's disease (AD) being the most common neurodegenerative disorder worldwide, no FDA-approved disease-modifying treatments have been approved for this condition since 2003. Neuronal-type alpha7 nicotinic acetylcholine receptors (α7nAChRs) play an essential role in cognitive functions, binding with extracellular β-amyloid (Aβ plaques) and inhibiting Aβ-induced neurotoxicity. α7nAChRs are impaired early in the course of AD; drugs targeting α7nAChRs are being hotly pursued as a treatment of AD. Encenicline, a partial selective agonist of α7nAChR and modulator of acetylcholine, failed in phase III trials because of gastrointestinal side effects. We, therefore, evaluated the efficacy of galantamine, a positive allosteric modulator at α7nAChRs and an acetylcholinesterase inhibitor, that has been used since 2000 as first-line treatment of mild-to-moderate dementia. This study highlights an important new benefit with galantamine. We found that galantamine inhibits Aβ1-42-induced apoptosis by activating the JNK signaling pathway, thus enhancing α7nAChR expression, and also inhibits the Akt pathway, which further increases autophagosome biogenesis and autophagy. These effects can be reproduced by α7nAChR overexpression in the absence of galantamine. Importantly, the α7 subunit protein sequence of α7nAChRs contains 3 LC3-interacting regions; our immunoprecipitation data show that α7 binds with the autophagosomal marker protein LC3. This is the first report to provide evidence showing that the cell surface receptor α7nAChR acts as a cargo carrier for LC3 binding for Aβ1-42 sequestration to autophagosomes, suggesting a novel mechanism for the neuroprotective efficacy of galantamine in AD.
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Affiliation(s)
- Ming-Wei Lin
- Department of Medical Research, E-Da Hospital/E-Da Cancer Hospital, Kaohsiung, 82445, Taiwan
- Regenerative Medicine and Cell Therapy Research Center, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Yi-Hung Chen
- Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan
- Chinese Medicine Research Center, China Medical University, Taichung, 40402, Taiwan
| | - Han-Ben Yang
- Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan
- Department of Life Sciences, Institute of Biomedical Science, National Chung Hsing University, Taichung, 40249, Taiwan
| | - Chi Chien Lin
- Department of Life Sciences, Institute of Biomedical Science, National Chung Hsing University, Taichung, 40249, Taiwan
| | - Shih-Ya Hung
- Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan.
- Division of Colorectal Surgery, China Medical University Hospital, Taichung, 40447, Taiwan.
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Dyrvig M, Mikkelsen JD, Lichota J. DNA methylation regulates CHRNA7 transcription and can be modulated by valproate. Neurosci Lett 2019; 704:145-152. [PMID: 30974230 DOI: 10.1016/j.neulet.2019.04.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 04/03/2019] [Accepted: 04/07/2019] [Indexed: 01/29/2023]
Abstract
The CHRNA7 gene encoding the α7 nicotinic acetylcholine receptor (nAChR) has repeatedly been linked with schizophrenia and the P50 sensory gating deficit. The α7 nAChR is considered a promising drug target for treatment of cognitive dysfunction in schizophrenia and improves memory and executive functions in patients and healthy individuals. However, clinical trials with pro-cognitive drugs are challenged by large inter-individual response variations and these have been linked to genotypic variations reducing CHRNA7 expression and α7 nAChR function. Genetic variants as well as environmental conditions may cause epigenetic dysregulation and it has previously been found that DNA methylation of a region surrounding the transcription start site of CHRNA7 is important for tissue specific regulation and gene silencing. In the present study we identify two additional regions involved in epigenetic regulation of the CHRNA7 promoter. In human temporal cortex we find large variations in expression of CHRNA7 and establish evidence for a significant correlation with DNA methylation levels of one region. We then establish evidence that genotypic variations can influence methylation levels of the CHRNA7 promoter. Epigenetic dysregulation can be reversed by pharmacological intervention and in HeLa cells. Valproate, a commonly used mood stabiliser, caused demethylation and increased CHRNA7 expression in HeLA cells. Similar demethylation effect and increased CHRNA7 expression was obtained in SH-SY5Y cells stimulated concomitantly with valproate and nicotine. In summary, both genetic and epigenetic information could be useful to predict treatment outcomes in patients and epigenetic modulation may serve as a mechanism for potentiating the effects of α7 nAChR agonists.
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Affiliation(s)
- Mads Dyrvig
- Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Denmark
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Jacek Lichota
- Laboratory of Metabolism Modifying Medicine, Department of Health Science and Technology, Aalborg University, Denmark.
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Bahous RH, Jadavji NM, Deng L, Cosín-Tomás M, Lu J, Malysheva O, Leung KY, Ho MK, Pallàs M, Kaliman P, Greene ND, Bedell BJ, Caudill MA, Rozen R. High dietary folate in pregnant mice leads to pseudo-MTHFR deficiency and altered methyl metabolism, with embryonic growth delay and short-term memory impairment in offspring. Hum Mol Genet 2017; 26:888-900. [PMID: 28069796 PMCID: PMC5409086 DOI: 10.1093/hmg/ddx004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/06/2016] [Accepted: 01/03/2017] [Indexed: 12/22/2022] Open
Abstract
Methylenetetrahydrofolate reductase (MTHFR) generates methyltetrahydrofolate for methylation reactions. Severe MTHFR deficiency results in homocystinuria and neurologic impairment. Mild MTHFR deficiency (677C > T polymorphism) increases risk for complex traits, including neuropsychiatric disorders. Although low dietary folate impacts brain development, recent concerns have focused on high folate intake following food fortification and increased vitamin use. Our goal was to determine whether high dietary folate during pregnancy affects brain development in murine offspring. Female mice were placed on control diet (CD) or folic acid-supplemented diet (FASD) throughout mating, pregnancy and lactation. Three-week-old male pups were evaluated for motor and cognitive function. Tissues from E17.5 embryos, pups and dams were collected for choline/methyl metabolite measurements, immunoblotting or gene expression of relevant enzymes. Brains were examined for morphology of hippocampus and cortex. Pups of FASD mothers displayed short-term memory impairment, decreased hippocampal size and decreased thickness of the dentate gyrus. MTHFR protein levels were reduced in FASD pup livers, with lower concentrations of phosphocholine and glycerophosphocholine in liver and hippocampus, respectively. FASD pup brains showed evidence of altered acetylcholine availability and Dnmt3a mRNA was reduced in cortex and hippocampus. E17.5 embryos and placentas from FASD dams were smaller. MTHFR protein and mRNA were reduced in embryonic liver, with lower concentrations of choline, betaine and phosphocholine. Embryonic brain displayed altered development of cortical layers. In summary, high folate intake during pregnancy leads to pseudo-MTHFR deficiency, disturbed choline/methyl metabolism, embryonic growth delay and memory impairment in offspring. These findings highlight the unintended negative consequences of supplemental folic acid.
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Affiliation(s)
- Renata H. Bahous
- Departments of Human Genetics and Pediatrics, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
| | - Nafisa M. Jadavji
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Liyuan Deng
- Departments of Human Genetics and Pediatrics, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
| | - Marta Cosín-Tomás
- Pharmacology Unit, Faculty of Pharmacy, Institut de Neurociència Universitat de Barcelona (IBUB), Nucli Universitari de Pedralbes, Barcelona, Spain
| | - Jessica Lu
- Departments of Human Genetics and Pediatrics, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
| | - Olga Malysheva
- Division of Nutritional Sciences and Genomics, Cornell University, Ithaca, NY, USA
| | - Kit-Yi Leung
- Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Ming-Kai Ho
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - Mercè Pallàs
- Pharmacology Unit, Faculty of Pharmacy, Institut de Neurociència Universitat de Barcelona (IBUB), Nucli Universitari de Pedralbes, Barcelona, Spain
| | - Perla Kaliman
- Institute of Biomedical Investigation of Barcelona, Spanish National Research Council, Barcelona, Spain
- Center for Mind and Brain, University of California Davis, Davis, CA, USA
| | - Nicholas D.E. Greene
- Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Barry J. Bedell
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - Marie A. Caudill
- Division of Nutritional Sciences and Genomics, Cornell University, Ithaca, NY, USA
| | - Rima Rozen
- Departments of Human Genetics and Pediatrics, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
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Kalkman HO, Feuerbach D. Modulatory effects of α7 nAChRs on the immune system and its relevance for CNS disorders. Cell Mol Life Sci 2016; 73:2511-30. [PMID: 26979166 PMCID: PMC4894934 DOI: 10.1007/s00018-016-2175-4] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/25/2016] [Accepted: 03/01/2016] [Indexed: 02/08/2023]
Abstract
The clinical development of selective alpha-7 nicotinic acetylcholine receptor (α7 nAChR) agonists has hitherto been focused on disorders characterized by cognitive deficits (e.g., Alzheimer's disease, schizophrenia). However, α7 nAChRs are also widely expressed by cells of the immune system and by cells with a secondary role in pathogen defense. Activation of α7 nAChRs leads to an anti-inflammatory effect. Since sterile inflammation is a frequently observed phenomenon in both psychiatric disorders (e.g., schizophrenia, melancholic and bipolar depression) and neurological disorders (e.g., Alzheimer's disease, Parkinson's disease, and multiple sclerosis), α7 nAChR agonists might show beneficial effects in these central nervous system disorders. In the current review, we summarize information on receptor expression, the intracellular signaling pathways they modulate and reasons for receptor dysfunction. Information from tobacco smoking, vagus nerve stimulation, and cholinesterase inhibition is used to evaluate the therapeutic potential of selective α7 nAChR agonists in these inflammation-related disorders.
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Affiliation(s)
- Hans O Kalkman
- Neuroscience Research, NIBR, Fabrikstrasse 22-3.001.02, 4002, Basel, Switzerland.
- , Gänsbühlgartenweg 7, 4132, Muttenz, Switzerland.
| | - Dominik Feuerbach
- Neuroscience Research, NIBR, Fabrikstrasse 22-3.001.02, 4002, Basel, Switzerland
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Identification and characterization of transcriptional control region of the human beta 1,4-mannosyltransferase gene. Cytotechnology 2015; 69:417-434. [PMID: 26608959 DOI: 10.1007/s10616-015-9929-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022] Open
Abstract
All asparagine-linked glycans (N-glycans) on the eukaryotic glycoproteins are primarily derived from dolichol-linked oligosaccharides (DLO), synthesized on the rough endoplasmic reticulum membrane. We have previously reported cloning and identification of the human gene, HMT-1, which encodes chitobiosyldiphosphodolichol beta-mannosyltransferase (β1,4-MT) involved in the early assembly of DLO. Considering that N-glycosylation is one of the most ubiquitous post-translational modifications for many eukaryotic proteins, the HMT-1 could be postulated as one of the housekeeping genes, but its transcriptional regulation remains to be investigated. Here we screened a 1 kb region upstream from HMT-1 open reading frame (ORF) for transcriptionally regulatory sequences by using chloramphenicol acetyl transferase (CAT) assay, and found that the region from -33 to -1 positions might act in HMT-1 transcription at basal level and that the region from -200 to -42 should regulate its transcription either positively or negatively. In addition, results with CAT assays suggested the possibility that two GATA-1 motifs and an Sp1 motif within a 200 bp region upstream from HMT-1 ORF might significantly upregulate HMT-1 transcription. On the contrary, the observations obtained from site-directed mutational analyses revealed that an NF-1/AP-2 overlapping motif located at -148 to -134 positions should serve as a strong silencer. The control of the HMT-1 transcription by these motifs resided within the 200 bp region could partially explain the variation of expression level among various human tissues, suggesting availability and importance of this region for regulatory role in HMT-1 expression.
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12
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Sinkus ML, Graw S, Freedman R, Ross RG, Lester HA, Leonard S. The human CHRNA7 and CHRFAM7A genes: A review of the genetics, regulation, and function. Neuropharmacology 2015; 96:274-88. [PMID: 25701707 PMCID: PMC4486515 DOI: 10.1016/j.neuropharm.2015.02.006] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 02/04/2015] [Accepted: 02/06/2015] [Indexed: 01/16/2023]
Abstract
The human α7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) is ubiquitously expressed in both the central nervous system and in the periphery. CHRNA7 is genetically linked to multiple disorders with cognitive deficits, including schizophrenia, bipolar disorder, ADHD, epilepsy, Alzheimer's disease, and Rett syndrome. The regulation of CHRNA7 is complex; more than a dozen mechanisms are known, one of which is a partial duplication of the parent gene. Exons 5-10 of CHRNA7 on chromosome 15 were duplicated and inserted 1.6 Mb upstream of CHRNA7, interrupting an earlier partial duplication of two other genes. The chimeric CHRFAM7A gene product, dupα7, assembles with α7 subunits, resulting in a dominant negative regulation of function. The duplication is human specific, occurring neither in primates nor in rodents. The duplicated α7 sequence in exons 5-10 of CHRFAM7A is almost identical to CHRNA7, and thus is not completely queried in high throughput genetic studies (GWAS). Further, pre-clinical animal models of the α7nAChR utilized in drug development research do not have CHRFAM7A (dupα7) and cannot fully model human drug responses. The wide expression of CHRNA7, its multiple functions and modes of regulation present challenges for study of this gene in disease. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Melissa L Sinkus
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Sharon Graw
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA; Veterans Affairs Medical Research Center, Denver, CO 80262, USA.
| | - Randal G Ross
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | - Henry A Lester
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA; Veterans Affairs Medical Research Center, Denver, CO 80262, USA.
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Chen T, Wang C, Sha S, Zhou L, Chen L, Chen L. Simvastatin Enhances Spatial Memory and Long-Term Potentiation in Hippocampal CA1 via Upregulation of α7 Nicotinic Acetylcholine Receptor. Mol Neurobiol 2015. [DOI: 10.1007/s12035-015-9344-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Brown KC, Perry HE, Lau JK, Jones DV, Pulliam JF, Thornhill BA, Crabtree CM, Luo H, Chen YC, Dasgupta P. Nicotine induces the up-regulation of the α7-nicotinic receptor (α7-nAChR) in human squamous cell lung cancer cells via the Sp1/GATA protein pathway. J Biol Chem 2013; 288:33049-59. [PMID: 24089524 PMCID: PMC3829154 DOI: 10.1074/jbc.m113.501601] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Nicotine, the addictive component of cigarettes, promotes lung cancer proliferation via the α7-nicotinic acetylcholine receptor (α7-nAChR) subtype. The present manuscript explores the effect of nicotine exposure on α7-nAChR levels in squamous cell carcinoma of the lung (SCC-L) in vitro and in vivo. Nicotine (at concentrations present in the plasma of average smokers) increased α7-nAChR levels in human SCC-L cell lines. Nicotine-induced up-regulation of α7-nAChR was confirmed in vivo by chicken chorioallantoic membrane models. We also observed that the levels of α7-nAChR in human SCC-L tumors (isolated from patients who are active smokers) correlated with their smoking history. Nicotine increased the levels of α7-nAChR mRNA and α7-nAChR transcription in human SCC-L cell lines and SCC-L tumors. Nicotine-induced up-regulation of α7-nAChR required GATA4 and GATA6. ChIP assays showed that nicotine induced the binding of GATA4 or GATA6 to Sp1 on the α7-nAChR promoter, thereby inducing its transcription and increasing its levels in human SCC-L. Our data are clinically relevant because SCC-L patients smoked for decades before being diagnosed with cancer. It may be envisaged that continuous exposure to nicotine (in such SCC-L patients) causes up-regulation of α7-nAChRs, which facilitates tumor growth and progression. Our results will also be relevant to many SCC-L patients exposed to nicotine via second-hand smoke, electronic cigarettes, and patches or gums to quit smoking.
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Affiliation(s)
- Kathleen C Brown
- From the Department of Pharmacology, Physiology, and Toxicology, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia 25755
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