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Steponenaite A, Lalic T, Atkinson L, Tanday N, Brown L, Mathie A, Cader ZM, Lall GS. TASK-3, two-pore potassium channels, contribute to circadian rhythms in the electrical properties of the suprachiasmatic nucleus and play a role in driving stable behavioural photic entrainment. Chronobiol Int 2024; 41:802-816. [PMID: 38757583 DOI: 10.1080/07420528.2024.2351515] [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: 08/24/2023] [Accepted: 04/19/2024] [Indexed: 05/18/2024]
Abstract
Stable and entrainable physiological circadian rhythms are crucial for overall health and well-being. The suprachiasmatic nucleus (SCN), the primary circadian pacemaker in mammals, consists of diverse neuron types that collectively generate a circadian profile of electrical activity. However, the mechanisms underlying the regulation of endogenous neuronal excitability in the SCN remain unclear. Two-pore domain potassium channels (K2P), including TASK-3, are known to play a significant role in maintaining SCN diurnal homeostasis by inhibiting neuronal activity at night. In this study, we investigated the role of TASK-3 in SCN circadian neuronal regulation and behavioural photoentrainment using a TASK-3 global knockout mouse model. Our findings demonstrate the importance of TASK-3 in maintaining SCN hyperpolarization during the night and establishing SCN sensitivity to glutamate. Specifically, we observed that TASK-3 knockout mice lacked diurnal variation in resting membrane potential and exhibited altered glutamate sensitivity both in vivo and in vitro. Interestingly, despite these changes, the mice lacking TASK-3 were still able to maintain relatively normal circadian behaviour.
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Affiliation(s)
| | - Tatjana Lalic
- Translational Molecular Neuroscience Group, University of Oxford, Oxford, UK
| | | | - Neil Tanday
- Medway School of Pharmacy, University of Kent, Kent, UK
| | - Lorna Brown
- Medway School of Pharmacy, University of Kent, Kent, UK
| | | | - Zameel M Cader
- Translational Molecular Neuroscience Group, University of Oxford, Oxford, UK
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Thapaliya B, Ray B, Farahdel B, Suresh P, Sapkota R, Holla B, Mahadevan J, Chen J, Vaidya N, Perrone-Bizzozero NI, Benegal V, Schumann G, Calhoun VD, Liu J. Cross-continental environmental and genome-wide association study on children and adolescent anxiety and depression. Front Psychiatry 2024; 15:1384298. [PMID: 38827440 PMCID: PMC11141390 DOI: 10.3389/fpsyt.2024.1384298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/17/2024] [Indexed: 06/04/2024] Open
Abstract
Anxiety and depression in children and adolescents warrant special attention as a public health concern given their devastating and long-term effects on development and mental health. Multiple factors, ranging from genetic vulnerabilities to environmental stressors, influence the risk for the disorders. This study aimed to understand how environmental factors and genomics affect children and adolescents anxiety and depression across three cohorts: Adolescent Brain and Cognitive Development Study (US, age of 9-10; N=11,875), Consortium on Vulnerability to Externalizing Disorders and Addictions (INDIA, age of 6-17; N=4,326) and IMAGEN (EUROPE, age of 14; N=1888). We performed data harmonization and identified the environmental impact on anxiety/depression using a linear mixed-effect model, recursive feature elimination regression, and the LASSO regression model. Subsequently, genome-wide association analyses with consideration of significant environmental factors were performed for all three cohorts by mega-analysis and meta-analysis, followed by functional annotations. The results showed that multiple environmental factors contributed to the risk of anxiety and depression during development, where early life stress and school support index had the most significant and consistent impact across all three cohorts. In both meta, and mega-analysis, SNP rs79878474 in chr11p15 emerged as a particularly promising candidate associated with anxiety and depression, despite not reaching genomic significance. Gene set analysis on the common genes mapped from top promising SNPs of both meta and mega analyses found significant enrichment in regions of chr11p15 and chr3q26, in the function of potassium channels and insulin secretion, in particular Kv3, Kir-6.2, SUR potassium channels encoded by the KCNC1, KCNJ11, and ABCCC8 genes respectively, in chr11p15. Tissue enrichment analysis showed significant enrichment in the small intestine, and a trend of enrichment in the cerebellum. Our findings provide evidences of consistent environmental impact from early life stress and school support index on anxiety and depression during development and also highlight the genetic association between mutations in potassium channels, which support the stress-depression connection via hypothalamic-pituitary-adrenal axis, along with the potential modulating role of potassium channels.
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Affiliation(s)
- Bishal Thapaliya
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
| | - Bhaskar Ray
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
| | - Britny Farahdel
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
| | - Pranav Suresh
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
| | - Ram Sapkota
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
| | - Bharath Holla
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Jayant Mahadevan
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Jiayu Chen
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
| | - Nilakshi Vaidya
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
- Centre for Population Neuroscience and Stratified Medicine, Department of Psychiatry and Neuroscience, Charité Universitätsmedizin Berlin, Berlin, Germany
| | | | - Vivek Benegal
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Gunter Schumann
- Centre for Population Neuroscience and Stratified Medicine, Department of Psychiatry and Neuroscience, Charité Universitätsmedizin Berlin, Berlin, Germany
- Centre for Population Neuroscience and Precision Medicine, Institute for Science and Technology of Brain-inspired Intelligence, Fudan University, Shanghai, China
| | - Vince D. Calhoun
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Jingyu Liu
- Tri-Institutional Center for Translational Research in NeuroImaging and Data Science, Atlanta, GA, United States
- Department of Computer Science, Georgia State University, Atlanta, GA, United States
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Shang Y, Wang X, Su S, Ji F, Shao D, Duan C, Chen T, Liang C, Zhang D, Lu H. Identifying of immune-associated genes for assessing the obesity-associated risk to the offspring in maternal obesity: A bioinformatics and machine learning. CNS Neurosci Ther 2024; 30:e14700. [PMID: 38544384 PMCID: PMC10973700 DOI: 10.1111/cns.14700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 05/14/2024] Open
Abstract
BACKGROUND Perinatal exposure to maternal obesity predisposes offspring to develop obesity later in life. Immune dysregulation in the hypothalamus, the brain center governing energy homeostasis, is pivotal in obesity development. This study aimed to identify key candidate genes associated with the risk of offspring obesity in maternal obesity. METHODS We obtained obesity-related datasets from the Gene Expression Omnibus (GEO) database. GSE135830 comprises gene expression data from the hypothalamus of mouse offspring in a maternal obesity model induced by a high-fat diet model (maternal high-fat diet (mHFD) group and maternal chow (mChow) group), while GSE127056 consists of hypothalamus microarray data from young adult mice with obesity (high-fat diet (HFD) and Chow groups). We identified differentially expressed genes (DEGs) and module genes using Limma and weighted gene co-expression network analysis (WGCNA), conducted functional enrichment analysis, and employed a machine learning algorithm (least absolute shrinkage and selection operator (LASSO) regression) to pinpoint candidate hub genes for diagnosing obesity-associated risk in offspring of maternal obesity. We constructed a nomogram receiver operating characteristic (ROC) curve to evaluate the diagnostic value. Additionally, we analyzed immune cell infiltration to investigate immune cell dysregulation in maternal obesity. Furthermore, we verified the expression of the candidate hub genes both in vivo and in vitro. RESULTS The GSE135830 dataset revealed 2868 DEGs between the mHFD offspring and the mChow group and 2627 WGCNA module genes related to maternal obesity. The overlap of DEGs and module genes in the offspring with maternal obesity in GSE135830 primarily enriched in neurodevelopment and immune regulation. In the GSE127056 dataset, 133 DEGs were identified in the hypothalamus of HFD-induced adult obese individuals. A total of 13 genes intersected between the GSE127056 adult obesity DEGs and the GSE135830 maternal obesity module genes that were primarily enriched in neurodevelopment and the immune response. Following machine learning, two candidate hub genes were chosen for nomogram construction. Diagnostic value evaluation by ROC analysis determined Sytl4 and Kncn2 as hub genes for maternal obesity in the offspring. A gene regulatory network with transcription factor-miRNA interactions was established. Dysregulated immune cells were observed in the hypothalamus of offspring with maternal obesity. Expression of Sytl4 and Kncn2 was validated in a mouse model of hypothalamic inflammation and a palmitic acid-stimulated microglial inflammation model. CONCLUSION Two candidate hub genes (Sytl4 and Kcnc2) were identified and a nomogram was developed to predict obesity risk in offspring with maternal obesity. These findings offer potential diagnostic candidate genes for identifying obesity-associated risks in the offspring of obese mothers.
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Affiliation(s)
- Yanxing Shang
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
| | - Xueqin Wang
- Department of Endocrinology, Affiliated Hospital 2Nantong UniversityNantongChina
| | - Sixuan Su
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
- Department of Pathogen Biology, Medical CollegeNantong UniversityNantongChina
| | - Feng Ji
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
| | - Donghai Shao
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
| | - Chengwei Duan
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
| | - Tianpeng Chen
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
| | - Caixia Liang
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
| | - Dongmei Zhang
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Nantong Clinical Medical College of Kangda College of Nanjing Medical UniversityNantongChina
- Nantong Municipal Key Laboratory of Metabolic Immunology and Disease MicroenvironmentNantong First People's HospitalNantongChina
- Department of Pathogen Biology, Medical CollegeNantong UniversityNantongChina
| | - Hongjian Lu
- Medical Research Center, Affiliated Hospital 2Nantong UniversityNantongChina
- Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit, Medical Research CenterNantong First People's HospitalNantongChina
- Department of Rehabilitation Medicine, Affiliated Hospital 2Nantong UniversityNantongChina
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Tang Y, Gan H, Wang B, Wang X, Li M, Yang Q, Geng M, Zhu P, Shao S, Tao F. Mediating effects of DNA methylation in the association between sleep quality and infertility among women of childbearing age. BMC Public Health 2023; 23:1802. [PMID: 37715240 PMCID: PMC10503064 DOI: 10.1186/s12889-023-16681-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 09/01/2023] [Indexed: 09/17/2023] Open
Abstract
BACKGROUND This study aims to investigate the association between sleep quality and infertility among women and to explore the mediating effects of DNA methylation in this association. METHODS This study is a population-based case-control study. The relationship between sleep quality and infertility was investigated in women with anovulatory infertility (n = 43) and healthy controls (n = 43). Genome-wide DNA methylation was profiled from peripheral blood samples using the Illumina Infinium Human Methylation 850k BeadChip. Differentially methylated CpGs between cases and controls were identified using the ChAMP R package. The mediating effect of DNA methylation between sleep quality and infertility among women was investigated using the Bayesian estimation method provided by the R package "mediation". RESULTS The survey included 86 women of reproductive age, with 43 participants each in the case and control groups. The average age of the women was 27.6 ± 2.8 years (case group: 27.8 ± 3.0 years, control group: 27.4 ± 2.7 years). A total of 262 differentially methylated CpGs corresponding to 185 genes were identified. Difficulty falling asleep was a risk factor for infertility in women (OR = 3.69, 95%CI = 1.14, 11.99), and a causal mediation effect of DNA methylation CpGs was found. The mediating effect coefficient for cg08298632 was 0.10 (95%CI = 0.01-0.22), and the proportion of the total effect mediated by this methylation site increased to 64.3%. CONCLUSION These results suggest that DNA methylation CpGs (cg08298632) play a significant role in the relationship between difficulty falling asleep and infertility in females. These findings contribute to our understanding of the underlying mechanisms that connect difficulty falling asleep and infertility in women. Further studies are necessary to fully understand the biological significance and potential therapeutic applications of these findings. The identified DNA methylation sites provide new and valuable insights and potential targets for future studies aiming to prevent and treat female infertility.
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Affiliation(s)
- Ying Tang
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- MOE Key Laboratory of Population Health Across Life Cycle, No 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Hong Gan
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- MOE Key Laboratory of Population Health Across Life Cycle, No 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Baolin Wang
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- MOE Key Laboratory of Population Health Across Life Cycle, No 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Xiaorui Wang
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Mengdie Li
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Qianhui Yang
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Menglong Geng
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Peng Zhu
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- MOE Key Laboratory of Population Health Across Life Cycle, No 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Shanshan Shao
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China
- MOE Key Laboratory of Population Health Across Life Cycle, No 81 Meishan Road, Hefei, 230032, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Fangbiao Tao
- Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, 230032, Anhui, China.
- MOE Key Laboratory of Population Health Across Life Cycle, No 81 Meishan Road, Hefei, 230032, Anhui, China.
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract, No 81 Meishan Road, Hefei, 230032, Anhui, China.
- Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei, 230032, Anhui, China.
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Hermanstyne TO, Yang ND, Granados-Fuentes D, Li X, Mellor RL, Jegla T, Herzog ED, Nerbonne JM. Kv12-encoded K+ channels drive the day-night switch in the repetitive firing rates of SCN neurons. J Gen Physiol 2023; 155:e202213310. [PMID: 37516908 PMCID: PMC10373311 DOI: 10.1085/jgp.202213310] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 05/11/2023] [Accepted: 07/06/2023] [Indexed: 07/31/2023] Open
Abstract
Considerable evidence suggests that day-night rhythms in the functional expression of subthreshold potassium (K+) channels regulate daily oscillations in the spontaneous firing rates of neurons in the suprachiasmatic nucleus (SCN), the master circadian pacemaker in mammals. The K+ conductance(s) driving these daily rhythms in the repetitive firing rates of SCN neurons, however, have not been identified. To test the hypothesis that subthreshold Kv12.1/Kv12.2-encoded K+ channels play a role, we obtained current-clamp recordings from SCN neurons in slices prepared from adult mice harboring targeted disruptions in the Kcnh8 (Kv12.1-/-) or Kcnh3 (Kv12.2-/-) locus. We found that mean nighttime repetitive firing rates were higher in Kv12.1-/- and Kv12.2-/- than in wild type (WT), SCN neurons. In marked contrast, mean daytime repetitive firing rates were similar in Kv12.1-/-, Kv12.2-/-, and WT SCN neurons, and the day-night difference in mean repetitive firing rates, a hallmark feature of WT SCN neurons, was eliminated in Kv12.1-/- and Kv12.2-/- SCN neurons. Similar results were obtained with in vivo shRNA-mediated acute knockdown of Kv12.1 or Kv12.2 in adult SCN neurons. Voltage-clamp experiments revealed that Kv12-encoded current densities in WT SCN neurons are higher at night than during the day. In addition, the pharmacological block of Kv12-encoded currents increased the mean repetitive firing rate of nighttime, but not daytime, in WT SCN neurons. Dynamic clamp-mediated subtraction of modeled Kv12-encoded currents also selectively increased the mean repetitive firing rates of nighttime WT SCN neurons. Despite the elimination of the nighttime decrease in the mean repetitive firing rates of SCN neurons, however, locomotor (wheel-running) activity remained rhythmic in Kv12.1-/-, Kv12.2-/-, and Kv12.1-targeted shRNA-expressing, and Kv12.2-targeted shRNA-expressing animals.
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Affiliation(s)
- Tracey O. Hermanstyne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Nien-Du Yang
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
| | | | - Xiaofan Li
- Department of Biology, The Pennsylvania State University, University Park, State College, PA, USA
| | - Rebecca L. Mellor
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Timothy Jegla
- Department of Biology, The Pennsylvania State University, University Park, State College, PA, USA
| | - Erik D. Herzog
- Department of Biology, Washington University, St. Louis, MO, USA
| | - Jeanne M. Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
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6
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Yang JJ, Huang RC. Afterhyperpolarization potential modulated by local [K +] o in K + diffusion-restricted extracellular space in the central clock of suprachiasmatic nucleus. Biomed J 2023; 46:100551. [PMID: 35863667 PMCID: PMC10345224 DOI: 10.1016/j.bj.2022.07.005] [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: 03/06/2022] [Revised: 05/31/2022] [Accepted: 07/14/2022] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Intercellular coupling is essential for the suprachiasmatic nucleus (SCN) to serve as a coherent central clock. Synaptic release of neurotransmitters and neuropeptides is critical for synchronizing SCN neurons. However, intercellular coupling via non-synaptic mechanisms has also been demonstrated. In particular, the abundant perikaryal appositions with morphological specializations in the narrow extracellular space (ECS) may hinder molecular diffusion to allow for ion accumulation or depletion. METHODS The SCN neurons were recorded in the whole-cell current-clamp mode, with pipette filled with high (26 mM)-Na+ or low (6 mM)-Na+ solution. RESULTS Cells recorded with high-Na+ pipette solution could fire spontaneous action potentials (AP) with peak AHP more negative than the calculated value of K+ equilibrium potential (EK) and with peak AP more positive than calculated ENa. Cells recorded with low-Na+ pipette solution could also have peak AHP more negative than calculated EK. In contrast, the resting membrane potential (RMP) was always less negative to calculated EK. The distribution and the averaged amplitude of peak AHP, peak AP, or RMP was similar between cells recorded with high-Na+ and low-Na+ solution pipette. In a number of cells, the peak AHP could increase from more positive to become more negative than calculated EK spontaneously or after treatments to hyperpolarize the RMP. TTX blocked the Na+ -dependent APs and tetraethylammonium (TEA), but not Ba2+ or Cd2+, markedly reduced the peak AHP. Perforated-patch cells could also but rarely fire APs with peak AHP more negative than calculated EK. CONCLUSION The result of peak AHP negative to calculated EK indicates that local [K+]o sensed by the TEA-sensitive AHP K+ channels must be lower than bulk [K+]o, most likely due to K+ clearance from K+ diffusion-restricted ECS by the Na+/K+-ATPase. The K+ diffusion-restricted ECS may allow for K+-mediated ionic interactions among neurons to regulate SCN excitability.
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Affiliation(s)
- Jyh-Jeen Yang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Rong-Chi Huang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan; Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
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7
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Yang ND, Mellor RL, Hermanstyne TO, Nerbonne JM. Effects of NALCN-Encoded Na + Leak Currents on the Repetitive Firing Properties of SCN Neurons Depend on K +-Driven Rhythmic Changes in Input Resistance. J Neurosci 2023; 43:5132-5141. [PMID: 37339878 PMCID: PMC10342223 DOI: 10.1523/jneurosci.0182-23.2023] [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: 01/30/2023] [Revised: 06/02/2023] [Accepted: 06/12/2023] [Indexed: 06/22/2023] Open
Abstract
Neurons in the suprachiasmatic nucleus (SCN) generate circadian changes in the rates of spontaneous action potential firing that regulate and synchronize daily rhythms in physiology and behavior. Considerable evidence suggests that daily rhythms in the repetitive firing rates (higher during the day than at night) of SCN neurons are mediated by changes in subthreshold potassium (K+) conductance(s). An alternative "bicycle" model for circadian regulation of membrane excitability in clock neurons, however, suggests that an increase in NALCN-encoded sodium (Na+) leak conductance underlies daytime increases in firing rates. The experiments reported here explored the role of Na+ leak currents in regulating daytime and nighttime repetitive firing rates in identified adult male and female mouse SCN neurons: vasoactive intestinal peptide-expressing (VIP+), neuromedin S-expressing (NMS+) and gastrin-releasing peptide-expressing (GRP+) cells. Whole-cell recordings from VIP+, NMS+, and GRP+ neurons in acute SCN slices revealed that Na+ leak current amplitudes/densities are similar during the day and at night, but have a larger impact on membrane potentials in daytime neurons. Additional experiments, using an in vivo conditional knockout approach, demonstrated that NALCN-encoded Na+ currents selectively regulate daytime repetitive firing rates of adult SCN neurons. Dynamic clamp-mediated manipulation revealed that the effects of NALCN-encoded Na+ currents on the repetitive firing rates of SCN neurons depend on K+ current-driven changes in input resistances. Together, these findings demonstrate that NALCN-encoded Na+ leak channels contribute to regulating daily rhythms in the excitability of SCN neurons by a mechanism that depends on K+ current-mediated rhythmic changes in intrinsic membrane properties.SIGNIFICANCE STATEMENT Elucidating the ionic mechanisms responsible for generating daily rhythms in the rates of spontaneous action potential firing of neurons in the suprachiasmatic nucleus (SCN), the master circadian pacemaker in mammals, is an important step toward understanding how the molecular clock controls circadian rhythms in physiology and behavior. While numerous studies have focused on identifying subthreshold K+ channel(s) that mediate day-night changes in the firing rates of SCN neurons, a role for Na+ leak currents has also been suggested. The results of the experiments presented here demonstrate that NALCN-encoded Na+ leak currents differentially modulate daily rhythms in the daytime/nighttime repetitive firing rates of SCN neurons as a consequence of rhythmic changes in subthreshold K+ currents.
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Affiliation(s)
- Nien-Du Yang
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63110
| | | | - Tracey O Hermanstyne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jeanne M Nerbonne
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63110
- Department of Medicine, Cardiovascular Division
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110
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8
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Thapaliya B, Ray B, Farahdel B, Suresh P, Sapkota R, Holla B, Mahadevan J, Chen J, Vaidya N, Perrone-Bizzozero N, Benegal V, Schumann G, Calhoun VD, Liu J. Cross-continental environmental and genome-wide association study on children and adolescent anxiety and depression. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.02.06.23285530. [PMID: 36798402 PMCID: PMC9934785 DOI: 10.1101/2023.02.06.23285530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Anxiety and depression in children and adolescents warrant special attention as a public health issue given their devastating and long-term effects on development and mental health. Multiple factors, ranging from genetic vulnerabilities to environmental stressors, influence the risk for the disorders. This study aimed to understand how environmental factors and genomics affect children and adolescents anxiety and depression across three cohorts: Adolescent Brain and Cognitive Development Study (US, age of 9-10), Consortium on Vulnerability to Externalizing Disorders and Addictions (INDIA, age of 6-17) and IMAGEN (EUROPE, age of 14). We performed data harmonization and identified the environmental impact on anxiety/depression using a linear mixed-effect model, recursive feature elimination regression, and the LASSO regression model. Subsequently, genome-wide association analyses with consideration of significant environmental factors were performed for all three cohorts by mega-analysis and meta-analysis, followed by functional annotations. The results showed that multiple environmental factors contributed to the risk of anxiety and depression during development, where early life stress and school risk had the most significant and consistent impact across all three cohorts. Both meta and mega-analysis identified a novel SNP rs79878474 in chr11p15 to be the most promising SNP associated with anxiety and depression. Gene set analysis on the common genes mapped from top promising SNPs of both meta and mega analyses found significant enrichment in regions of chr11p15 and chr3q26, in the function of potassium channels and insulin secretion, in particular Kv3, Kir-6.2, SUR potassium channels encoded by the KCNC1, KCNJ11, and ABCCC8 genes respectively, in chr11p15. Tissue enrichment analysis showed significant enrichment in the small intestine and a trend of enrichment in the cerebellum. Our findings provide evidence of consistent environmental impact from early life stress and school risks on anxiety and depression during development and also highlight the genetic association between mutations in potassium channels along with the potential role of the cerebellum region, which are worthy of further investigation.
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Affiliation(s)
- Bishal Thapaliya
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
| | - Bhaskar Ray
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
| | - Britny Farahdel
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
| | - Pranav Suresh
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
| | - Ram Sapkota
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
| | | | | | - Bharath Holla
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Jayant Mahadevan
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Jiayu Chen
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
| | - Nilakshi Vaidya
- Centre for Population Neuroscience and Stratified Medicine, Department of Psychiatry and Neuroscience, Charité Universitätsmedizin Berlin, Germany
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Nora Perrone-Bizzozero
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Vivek Benegal
- Centre for Addiction Medicine, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Gunter Schumann
- Centre for Population Neuroscience and Stratified Medicine, Department of Psychiatry and Neuroscience, Charité Universitätsmedizin Berlin, Germany
- Centre for Population Neuroscience and Precision Medicine, Institute for Science and Technology of Brain-inspired Intelligence, Fudan University, Shanghai, China
| | - Vince D. Calhoun
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Jingyu Liu
- Tri-Institutional Center for Translational Research in Neuro Imaging and Data Science
- Department of Computer Science, Georgia State University, Atlanta, USA
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9
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Hermanstyne TO, Yang ND, Granados-Fuentes D, Li X, Mellor RL, Jegla T, Herzog ED, Nerbonne JM. Kv12-Encoded K + Channels Drive the Day-Night Switch in the Repetitive Firing Rates of SCN Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.30.526323. [PMID: 36778242 PMCID: PMC9915524 DOI: 10.1101/2023.01.30.526323] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Considerable evidence suggests that day-night rhythms in the functional expression of subthreshold potassium (K + ) channels regulate daily oscillations in the rates of spontaneous action potential firing of neurons in the suprachiasmatic nucleus (SCN), the master circadian pacemaker in mammals. The K + conductance(s) driving these daily rhythms in repetitive firing rates, however, have not been identified. To test the hypothesis that subthreshold Kv12.1/Kv12.2-encoded K + channels play a role, we obtained current-clamp recordings from SCN neurons in slices prepared from adult mice harboring targeted disruptions in the Kcnh8 (Kv12.1 -/- ) or Kcnh3 (Kv12.2 -/- ) locus. We found that mean nighttime repetitive firing rates were higher in Kv12.1 -/- and Kv12.2 -/- , than in wild type (WT), SCN neurons. In marked contrast, mean daytime repetitive firing rates were similar in Kv12.1 -/- , Kv12.2 -/- and WT SCN neurons, and the day-night difference in mean repetitive firing rates, a hallmark feature of WT SCN neurons, was eliminated in Kv12.1 -/- and Kv12.2 -/- SCN neurons. Similar results were obtained with in vivo shRNA-mediated acute knockdown of Kv12.1 or Kv12.2 in adult SCN neurons. Voltage-clamp experiments revealed that Kv12-encoded current densities in WT SCN neurons are higher at night than during the day. In addition, pharmacological block of Kv12-encoded currents increased the mean repetitive firing rate of nighttime, but not daytime, in WT SCN neurons. Dynamic clamp-mediated subtraction of modeled Kv12-encoded currents also selectively increased the mean repetitive firing rates of nighttime WT SCN neurons. Despite the elimination of nighttime decrease in the mean repetitive firing rates of SCN neurons, however, locomotor (wheel-running) activity remained rhythmic in Kv12.1 -/- , Kv12.2 -/- , Kv12.1-targeted shRNA-expressing, and Kv12.2-targeted shRNA-expressing animals.
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Affiliation(s)
- Tracey O. Hermanstyne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Nien-Du Yang
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO
| | | | - Xiaofan Li
- Department of Biology, The Pennsylvania State University, University Park, PA
| | - Rebecca L. Mellor
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
| | - Timothy Jegla
- Department of Biology, The Pennsylvania State University, University Park, PA
| | - Erik D. Herzog
- Department of Biology, Washington University, St. Louis, MO
| | - Jeanne M. Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO
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10
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Chi G, Liang Q, Sridhar A, Cowgill JB, Sader K, Radjainia M, Qian P, Castro-Hartmann P, Venkaya S, Singh NK, McKinley G, Fernandez-Cid A, Mukhopadhyay SMM, Burgess-Brown NA, Delemotte L, Covarrubias M, Dürr KL. Cryo-EM structure of the human Kv3.1 channel reveals gating control by the cytoplasmic T1 domain. Nat Commun 2022; 13:4087. [PMID: 35840580 PMCID: PMC9287412 DOI: 10.1038/s41467-022-29594-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 03/24/2022] [Indexed: 11/26/2022] Open
Abstract
Kv3 channels have distinctive gating kinetics tailored for rapid repolarization in fast-spiking neurons. Malfunction of this process due to genetic variants in the KCNC1 gene causes severe epileptic disorders, yet the structural determinants for the unusual gating properties remain elusive. Here, we present cryo-electron microscopy structures of the human Kv3.1a channel, revealing a unique arrangement of the cytoplasmic tetramerization domain T1 which facilitates interactions with C-terminal axonal targeting motif and key components of the gating machinery. Additional interactions between S1/S2 linker and turret domain strengthen the interface between voltage sensor and pore domain. Supported by molecular dynamics simulations, electrophysiological and mutational analyses, we identify several residues in the S4/S5 linker which influence the gating kinetics and an electrostatic interaction between acidic residues in α6 of T1 and R449 in the pore-flanking S6T helices. These findings provide insights into gating control and disease mechanisms and may guide strategies for the design of pharmaceutical drugs targeting Kv3 channels.
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Affiliation(s)
- Gamma Chi
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
| | - Qiansheng Liang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, 19107, UK
| | - Akshay Sridhar
- Department of Applied Physics, Science for Life Laboratory, KTH, Solna, Sweden
| | - John B Cowgill
- Department of Applied Physics, Science for Life Laboratory, KTH, Solna, Sweden
| | - Kasim Sader
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, Netherlands
| | - Mazdak Radjainia
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, Netherlands
| | - Pu Qian
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, Netherlands
| | - Pablo Castro-Hartmann
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, Netherlands
| | - Shayla Venkaya
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Exscientia Ltd., The Schrödinger Building, Heatley Road, The Oxford Science Park, Oxford, OX4 4GE, UK
| | - Nanki Kaur Singh
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
| | - Gavin McKinley
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
| | - Alejandra Fernandez-Cid
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Exact Sciences Ltd., The Sherard Building, Edmund Halley Road, The Oxford Science Park, Oxford, OX4 4DQ, UK
| | - Shubhashish M M Mukhopadhyay
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Exscientia Ltd., The Schrödinger Building, Heatley Road, The Oxford Science Park, Oxford, OX4 4GE, UK
| | - Nicola A Burgess-Brown
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK
- Exact Sciences Ltd., The Sherard Building, Edmund Halley Road, The Oxford Science Park, Oxford, OX4 4DQ, UK
| | - Lucie Delemotte
- Department of Applied Physics, Science for Life Laboratory, KTH, Solna, Sweden
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, 19107, UK
| | - Katharina L Dürr
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK.
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK.
- OMass Therapeutics, Ltd., The Schrödinger Building, Heatley Road, The Oxford Science Park, Oxford, OX4 4GE, UK.
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11
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Ma L, Du Y, Hui Y, Li N, Fan B, Zhang X, Li X, Hong W, Wu Z, Zhang S, Zhou S, Xu X, Zhou Z, Jiang C, Liu L, Zhang X. Developmental programming and lineage branching of early human telencephalon. EMBO J 2021; 40:e107277. [PMID: 34558085 DOI: 10.15252/embj.2020107277] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 08/21/2021] [Accepted: 08/24/2021] [Indexed: 01/02/2023] Open
Abstract
The dorsal and ventral human telencephalons contain different neuronal subtypes, including glutamatergic, GABAergic, and cholinergic neurons, and how these neurons are generated during early development is not well understood. Using scRNA-seq and stringent validations, we reveal here a developmental roadmap for human telencephalic neurons. Both dorsal and ventral telencephalic radial glial cells (RGs) differentiate into neurons via dividing intermediate progenitor cells (IPCs_div) and early postmitotic neuroblasts (eNBs). The transcription factor ASCL1 plays a key role in promoting fate transition from RGs to IPCs_div in both regions. RGs from the regionalized neuroectoderm show heterogeneity, with restricted glutamatergic, GABAergic, and cholinergic differentiation potencies. During neurogenesis, IPCs_div gradually exit the cell cycle and branch into sister eNBs to generate distinct neuronal subtypes. Our findings highlight a general RGs-IPCs_div-eNBs developmental scheme for human telencephalic progenitors and support that the major neuronal fates of human telencephalon are predetermined during dorsoventral regionalization with neuronal diversity being further shaped during neurogenesis and neural circuit integration.
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Affiliation(s)
- Lin Ma
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.,Department of Pathology and Pathophysiology, School of Medicine, Tongji University, Shanghai, China
| | - Yanhua Du
- Department of Immunology and Microbiology, Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yi Hui
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Nan Li
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Beibei Fan
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Xiaojie Zhang
- Department of Obstetrics and Gynecology, Shanghai Baoshan Luodian Hospital, Shanghai, China
| | - Xiaocui Li
- Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Wei Hong
- Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Zhiping Wu
- Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Shuwei Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Shanshan Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Xiangjie Xu
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Zhongshu Zhou
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China
| | - Cizhong Jiang
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China
| | - Ling Liu
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.,Department of Pathology and Pathophysiology, School of Medicine, Tongji University, Shanghai, China
| | - Xiaoqing Zhang
- Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.,Key Laboratory of Neuroregeneration of Shanghai Universities, School of Medicine, Tongji University, Shanghai, China.,Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai, China.,Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, Shanghai, China.,Brain and Spinal Cord Innovative Research Center, School of Medicine, Tongji University, Shanghai, China.,Tsingtao Advanced Research Institute, Tongji University, Qingdao, China
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12
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Bano-Otalora B, Martial F, Harding C, Bechtold DA, Allen AE, Brown TM, Belle MDC, Lucas RJ. Bright daytime light enhances circadian amplitude in a diurnal mammal. Proc Natl Acad Sci U S A 2021; 118:e2100094118. [PMID: 34031246 PMCID: PMC8179182 DOI: 10.1073/pnas.2100094118] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mammalian circadian rhythms are orchestrated by a master pacemaker in the hypothalamic suprachiasmatic nuclei (SCN), which receives information about the 24 h light-dark cycle from the retina. The accepted function of this light signal is to reset circadian phase in order to ensure appropriate synchronization with the celestial day. Here, we ask whether light also impacts another key property of the circadian oscillation, its amplitude. To this end, we measured circadian rhythms in behavioral activity, body temperature, and SCN electrophysiological activity in the diurnal murid rodent Rhabdomys pumilio following stable entrainment to 12:12 light-dark cycles at four different daytime intensities (ranging from 18 to 1,900 lx melanopic equivalent daylight illuminance). R. pumilio showed strongly diurnal activity and body temperature rhythms in all conditions, but measures of rhythm robustness were positively correlated with daytime irradiance under both entrainment and subsequent free run. Whole-cell and extracellular recordings of electrophysiological activity in ex vivo SCN revealed substantial differences in electrophysiological activity between dim and bright light conditions. At lower daytime irradiance, daytime peaks in SCN spontaneous firing rate and membrane depolarization were substantially depressed, leading to an overall marked reduction in the amplitude of circadian rhythms in spontaneous activity. Our data reveal a previously unappreciated impact of daytime light intensity on SCN physiology and the amplitude of circadian rhythms and highlight the potential importance of daytime light exposure for circadian health.
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Affiliation(s)
- Beatriz Bano-Otalora
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Franck Martial
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Court Harding
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - David A Bechtold
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Annette E Allen
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Timothy M Brown
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Mino D C Belle
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Exeter EX4 4PS, United Kingdom
| | - Robert J Lucas
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
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13
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Tabuchi M, Coates KE, Bautista OB, Zukowski LH. Light/Clock Influences Membrane Potential Dynamics to Regulate Sleep States. Front Neurol 2021; 12:625369. [PMID: 33854471 PMCID: PMC8039321 DOI: 10.3389/fneur.2021.625369] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/15/2021] [Indexed: 11/13/2022] Open
Abstract
The circadian rhythm is a fundamental process that regulates the sleep-wake cycle. This rhythm is regulated by core clock genes that oscillate to create a physiological rhythm of circadian neuronal activity. However, we do not know much about the mechanism by which circadian inputs influence neurons involved in sleep-wake architecture. One possible mechanism involves the photoreceptor cryptochrome (CRY). In Drosophila, CRY is receptive to blue light and resets the circadian rhythm. CRY also influences membrane potential dynamics that regulate neural activity of circadian clock neurons in Drosophila, including the temporal structure in sequences of spikes, by interacting with subunits of the voltage-dependent potassium channel. Moreover, several core clock molecules interact with voltage-dependent/independent channels, channel-binding protein, and subunits of the electrogenic ion pump. These components cooperatively regulate mechanisms that translate circadian photoreception and the timing of clock genes into changes in membrane excitability, such as neural firing activity and polarization sensitivity. In clock neurons expressing CRY, these mechanisms also influence synaptic plasticity. In this review, we propose that membrane potential dynamics created by circadian photoreception and core clock molecules are critical for generating the set point of synaptic plasticity that depend on neural coding. In this way, membrane potential dynamics drive formation of baseline sleep architecture, light-driven arousal, and memory processing. We also discuss the machinery that coordinates membrane excitability in circadian networks found in Drosophila, and we compare this machinery to that found in mammalian systems. Based on this body of work, we propose future studies that can better delineate how neural codes impact molecular/cellular signaling and contribute to sleep, memory processing, and neurological disorders.
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Affiliation(s)
- Masashi Tabuchi
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States
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14
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Liu H, Rastogi A, Narain P, Xu Q, Sabanovic M, Alhammadi AD, Guo L, Cao JL, Zhang H, Aqel H, Mlambo V, Rezgui R, Radwan B, Chaudhury D. Blunted diurnal firing in lateral habenula projections to dorsal raphe nucleus and delayed photoentrainment in stress-susceptible mice. PLoS Biol 2021; 19:e3000709. [PMID: 33690628 PMCID: PMC7984642 DOI: 10.1371/journal.pbio.3000709] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/22/2021] [Accepted: 02/04/2021] [Indexed: 01/29/2023] Open
Abstract
Daily rhythms are disrupted in patients with mood disorders. The lateral habenula (LHb) and dorsal raphe nucleus (DRN) contribute to circadian timekeeping and regulate mood. Thus, pathophysiology in these nuclei may be responsible for aberrations in daily rhythms during mood disorders. Using the 15-day chronic social defeat stress (CSDS) paradigm and in vitro slice electrophysiology, we measured the effects of stress on diurnal rhythms in firing of LHb cells projecting to the DRN (cellsLHb→DRN) and unlabeled DRN cells. We also performed optogenetic experiments to investigate if increased firing in cellsLHb→DRN during exposure to a weak 7-day social defeat stress (SDS) paradigm induces stress-susceptibility. Last, we investigated whether exposure to CSDS affected the ability of mice to photoentrain to a new light–dark (LD) cycle. The cellsLHb→DRN and unlabeled DRN cells of stress-susceptible mice express greater blunted diurnal firing compared to stress-näive (control) and stress-resilient mice. Daytime optogenetic activation of cellsLHb→DRN during SDS induces stress-susceptibility which shows the direct correlation between increased activity in this circuit and putative mood disorders. Finally, we found that stress-susceptible mice are slower, while stress-resilient mice are faster, at photoentraining to a new LD cycle. Our findings suggest that exposure to strong stressors induces blunted daily rhythms in firing in cellsLHb→DRN, DRN cells and decreases the initial rate of photoentrainment in susceptible-mice. In contrast, resilient-mice may undergo homeostatic adaptations that maintain daily rhythms in firing in cellsLHb→DRN and also show rapid photoentrainment to a new LD cycle. Daily rhythms are disrupted in patients suffering from mood disorders, and it is known that the lateral habenula and dorsal raphe nucleus contribute to circadian timekeeping and regulate mood. This study shows that stress-susceptible mice have blunted and inverted diurnal firing rhythms in lateral habenula cells that project to the dorsal raphe nucleus, and have a slow rate of photoentrainment to a new light cycle.
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Affiliation(s)
- He Liu
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
- Department of Anesthesiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesiology & Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, The Xuzhou Medical University, Xuzhou, China
| | - Ashutosh Rastogi
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Priyam Narain
- Center for Genomics and Systems Biology, New York University Abu Dhabi, United Arab Emirates
| | - Qing Xu
- Center for Genomics and Systems Biology, New York University Abu Dhabi, United Arab Emirates
| | - Merima Sabanovic
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | | | - Lihua Guo
- Center for Genomics and Systems Biology, New York University Abu Dhabi, United Arab Emirates
| | - Jun-Li Cao
- Department of Anesthesiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
- Center for Genomics and Systems Biology, New York University Abu Dhabi, United Arab Emirates
| | - Hongxing Zhang
- Department of Anesthesiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Hala Aqel
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Vongai Mlambo
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Rachid Rezgui
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Basma Radwan
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Dipesh Chaudhury
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
- * E-mail:
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15
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Liu H, Rastogi A, Sabanovic M, Alhammadi AD, Xu Q, Guo L, Cao J, Zhang H, Narain P, Aqel H, Mlambo V, Rezgui R, Radwan B, Chaudhury D. Blunted Diurnal Firing in Lateral Habenula Projections to Dorsal Raphe Nucleus and Delayed Photoentrainment in Stress-Susceptible Mice.. [DOI: 10.1101/2020.03.19.998732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
Abstract
ABSTRACTDaily rhythms are disrupted in patients suffering from mood disorders. The lateral habenula (LHb) and dorsal raphe nucleus (DRN) contribute to circadian timekeeping and regulate mood. Thus, pathophysiology in these nuclei may be responsible for aberrations in daily rhythms during mood disorders. Using the chronic social defeat stress (CSDS) paradigm and in-vitro slice electrophysiology we measured the effects of stress on diurnal rhythms in firing of LHb cells projecting to the DRN (cellsLHb→DRN) and DRN cells alone. We also performed optogenetic experiments to investigate if increased firing in cellsLHb→DRN during exposure to subthreshold social defeat stress (SSDS), induces stress-susceptibility. Last we investigated whether exposure to CSDS affected the ability of mice to phototentrain to a new LD cycle. The cellsLHb→DRN and DRN cells alone of stress-susceptible mice express greater blunted diurnal firing compared to stress-naive (control) and stress-resilient mice. Day-time optogenetic activation of cellsLHb→DRN during SSDS induces stress-susceptibility which shows the direct correlation between increased activity in this circuit and putative mood disorders. Finally, we found that stress-susceptible mice are slower, while stress-resilient mice are faster, at photoentraining to a new LD cycle. Our findings suggest that CSDS induces blunted daily rhythms in firing in cellsLHb→DRN and slow rate of photoentrainment in susceptible-mice. In contrast, resilientmice may undergo homeostatic adaptations that maintain daily rhythms in firing in cellsLHb→DRN and also show rapid photoentrainment to a new LD-cycle.
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16
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Harvey JRM, Plante AE, Meredith AL. Ion Channels Controlling Circadian Rhythms in Suprachiasmatic Nucleus Excitability. Physiol Rev 2020; 100:1415-1454. [PMID: 32163720 DOI: 10.1152/physrev.00027.2019] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Animals synchronize to the environmental day-night cycle by means of an internal circadian clock in the brain. In mammals, this timekeeping mechanism is housed in the suprachiasmatic nucleus (SCN) of the hypothalamus and is entrained by light input from the retina. One output of the SCN is a neural code for circadian time, which arises from the collective activity of neurons within the SCN circuit and comprises two fundamental components: 1) periodic alterations in the spontaneous excitability of individual neurons that result in higher firing rates during the day and lower firing rates at night, and 2) synchronization of these cellular oscillations throughout the SCN. In this review, we summarize current evidence for the identity of ion channels in SCN neurons and the mechanisms by which they set the rhythmic parameters of the time code. During the day, voltage-dependent and independent Na+ and Ca2+ currents, as well as several K+ currents, contribute to increased membrane excitability and therefore higher firing frequency. At night, an increase in different K+ currents, including Ca2+-activated BK currents, contribute to membrane hyperpolarization and decreased firing. Layered on top of these intrinsically regulated changes in membrane excitability, more than a dozen neuromodulators influence action potential activity and rhythmicity in SCN neurons, facilitating both synchronization and plasticity of the neural code.
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Affiliation(s)
- Jenna R M Harvey
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Amber E Plante
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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17
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Smith P, Buhl E, Tsaneva-Atanasova K, Hodge JJL. Shaw and Shal voltage-gated potassium channels mediate circadian changes in Drosophila clock neuron excitability. J Physiol 2019; 597:5707-5722. [PMID: 31612994 DOI: 10.1113/jp278826] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/03/2019] [Indexed: 01/08/2023] Open
Abstract
As in mammals, Drosophila circadian clock neurons display rhythms of activity with higher action potential firing rates and more positive resting membrane potentials during the day. This rhythmic excitability has been widely observed but, critically, its regulation remains unresolved. We have characterized and modelled the changes underlying these electrical activity rhythms in the lateral ventral clock neurons (LNvs). We show that currents mediated by the voltage-gated potassium channels Shaw (Kv3) and Shal (Kv4) oscillate in a circadian manner. Disruption of these channels, by expression of dominant negative (DN) subunits, leads to changes in circadian locomotor activity and shortens lifespan. LNv whole-cell recordings then show that changes in Shaw and Shal currents drive changes in action potential firing rate and that these rhythms are abolished when the circadian molecular clock is stopped. A whole-cell biophysical model using Hodgkin-Huxley equations can recapitulate these changes in electrical activity. Based on this model and by using dynamic clamp to manipulate clock neurons directly, we can rescue the pharmacological block of Shaw and Shal, restore the firing rhythm, and thus demonstrate the critical importance of Shaw and Shal. Together, these findings point to a key role for Shaw and Shal in controlling circadian firing of clock neurons and show that changes in clock neuron currents can account for this. Moreover, with dynamic clamp we can switch the LNvs between morning-like and evening-like states of electrical activity. We conclude that changes in Shaw and Shal underlie the daily oscillation in LNv firing rate.
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Affiliation(s)
- Philip Smith
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Edgar Buhl
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Krasimira Tsaneva-Atanasova
- Department of Mathematics and Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - James J L Hodge
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK
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18
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Nabel AL, Callan AR, Gleiss SA, Kladisios N, Leibold C, Felmy F. Distinct Distribution Patterns of Potassium Channel Sub-Units in Somato-Dendritic Compartments of Neurons of the Medial Superior Olive. Front Cell Neurosci 2019; 13:38. [PMID: 30837841 PMCID: PMC6390502 DOI: 10.3389/fncel.2019.00038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 01/23/2019] [Indexed: 12/17/2022] Open
Abstract
Coincidence detector neurons of the medial superior olive (MSO) are sensitive to interaural time differences in the range of a few tens of microseconds. The biophysical basis for this remarkable acuity is a short integration time constant of the membrane, which is achieved by large low voltage-activated potassium and hyperpolarization-activated inward cation conductances. Additional temporal precision is thought to be achieved through a sub-cellular distribution of low voltage-activated potassium channel expression biased to the soma. To evaluate the contribution of potassium channels, we investigated the presence and sub-cellular distribution profile of seven potassium channel sub-units in adult MSO neurons of gerbils. We find that low- and high voltage-activated potassium channels are present with distinct sub-cellular distributions. Overall, low voltage-activated potassium channels appear to be biased to the soma while high voltage-activated potassium channels are more evenly distributed and show a clear expression at distal dendrites. Additionally, low voltage-activated potassium channel sub-units co-localize with glycinergic inputs while HCN1 channels co-localize more with high voltage-activated potassium channels. Functionally, high voltage-activated potassium currents are already active at low voltages near the resting potential. We describe a possible role of high voltage-activated potassium channels in modulating EPSPs in a computational model and contributing to setting the integration time window of coincidental inputs. Our data shows that MSO neurons express a large set of different potassium channels with distinct functional relevance.
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Affiliation(s)
- Alisha L Nabel
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.,Graduate School for Systemic Neurosciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Alexander R Callan
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.,Graduate School for Systemic Neurosciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Sarah A Gleiss
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.,Graduate School for Systemic Neurosciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nikolaos Kladisios
- Institute of Zoology, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Christian Leibold
- Computational Neuroscience, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Felix Felmy
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.,Institute of Zoology, University of Veterinary Medicine Hannover, Hanover, Germany
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19
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Kuljis D, Kudo T, Tahara Y, Ghiani CA, Colwell CS. Pathophysiology in the suprachiasmatic nucleus in mouse models of Huntington's disease. J Neurosci Res 2018; 96:1862-1875. [PMID: 30168855 DOI: 10.1002/jnr.24320] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/04/2018] [Accepted: 08/07/2018] [Indexed: 12/30/2022]
Abstract
Disturbances in sleep/wake cycle are a common complaint of individuals with Huntington's disease (HD) and are displayed by HD mouse models. The underlying mechanisms, including the possible role of the circadian timing system, are not well established. The BACHD mouse model of HD exhibits disrupted behavioral and physiological rhythms, including decreased electrical activity in the central circadian clock (suprachiasmatic nucleus, SCN). In this study, electrophysiological techniques were used to explore the ionic underpinning of the reduced spontaneous neural activity in male mice. We found that SCN neural activity rhythms were lost early in the disease progression and was accompanied by loss of the normal daily variation in resting membrane potential in the mutant SCN neurons. The low neural activity could be transiently reversed by direct current injection or application of exogenous N-methyl-d-aspartate (NMDA) thus demonstrating that the neurons have the capacity to discharge at WT levels. Exploring the potassium currents known to regulate the electrical activity of SCN neurons, our most striking finding was that these cells in the mutants exhibited an enhancement in the large-conductance calcium activated K+ (BK) currents. The expression of the pore forming subunit (Kcnma1) of the BK channel was higher in the mutant SCN. We found a similar decrease in daytime electrical activity and enhancement in the magnitude of the BK currents early in disease in another HD mouse model (Q175). These findings suggest that SCN neurons of both HD models exhibit early pathophysiology and that dysregulation of BK current may be responsible.
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Affiliation(s)
- Dika Kuljis
- Department of Neurobiology, University of California Los Angeles, Los Angeles, California.,Department of Biological Sciences, Mellon Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Takashi Kudo
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California.,Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Yu Tahara
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California
| | - Cristina A Ghiani
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California.,Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California
| | - Christopher S Colwell
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California
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20
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Belle MDC, Allen CN. The circadian clock: A tale of genetic-electrical interplay and synaptic integration. CURRENT OPINION IN PHYSIOLOGY 2018; 5:75-79. [PMID: 31011692 DOI: 10.1016/j.cophys.2018.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pioneering work in Drosophila uncovered the building blocks of the molecular clock, consisting of transcription-translation feedback loops (TTFLs). Subsequent experimental work demonstrated that the mammalian TTFL is localized in cells and tissues throughout the brain and body. Further research established that neuronal activity forms an essential aspect of clock function. However, how the membrane electrical activity of clock neurons of the suprachiasmatic nucleus collaborate with the TTFL to drive circadian behaviors remains mostly unknown. Intercellular communication synchronizes the individual circadian oscillators to produce a precise and coherent circadian output. Here, we briefly review significant research that is increasing our understanding of the critical interactions between the TTFL and neuronal and glial activity in the generation of circadian timing signals.
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Affiliation(s)
- Mino D C Belle
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Exeter, EX4 4PS, UK.
| | - Charles N Allen
- Oregon Institute of Occupational Health Sciences and Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239, USA.
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21
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Antimanic Efficacy of a Novel Kv3 Potassium Channel Modulator. Neuropsychopharmacology 2018; 43:435-444. [PMID: 28857068 PMCID: PMC5729564 DOI: 10.1038/npp.2017.155] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 07/12/2017] [Accepted: 07/14/2017] [Indexed: 11/08/2022]
Abstract
Kv3.1 and Kv3.2 voltage-gated potassium channels are expressed on parvalbumin-positive GABAergic interneurons in corticolimbic brain regions and contribute to high-frequency neural firing. The channels are also expressed on GABAergic neurons of the basal ganglia, substantia nigra, and ventral tegmental area (VTA) where they regulate firing patterns critical for movement control, reward, and motivation. Modulation of Kv3.1 and Kv3.2 channels may therefore have potential in the treatment of disorders in which these systems have been implicated, such as bipolar disorder. Following the recent development of a potassium channel modulator, AUT1-an imidazolidinedione compound that specifically increases currents mediated by Kv3.1 and Kv3.2 channels in recombinant systems-we report that the compound is able to reverse 'manic-like' behavior in two mouse models: amphetamine-induced hyperactivity and ClockΔ19 mutants. AUT1 completely prevented amphetamine-induced hyperactivity in a dose-dependent manner, similar to the atypical antipsychotic, clozapine. Similar efficacy was observed in Kv3.2 knockout mice. In contrast, AUT1 was unable to prevent amphetamine-induced hyperactivity in mice lacking Kv3.1 channels. Notably, Kv3.1-null mice displayed baseline hyperlocomotion, reduced anxiety-like behavior, and antidepressant-like behavior. In ClockΔ19 mice, AUT1 reversed hyperactivity. Furthermore, AUT1 application modulated firing frequency and action potential properties of ClockΔ19 VTA dopamine neurons potentially through network effects. Kv3.1 protein levels in the VTA of ClockΔ19 and WT mice were unaltered by acute AUT1 treatment. Taken together, these results suggest that the modulation of Kv3.1 channels may provide a novel approach to the treatment of bipolar mania.
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22
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Kaczmarek LK, Zhang Y. Kv3 Channels: Enablers of Rapid Firing, Neurotransmitter Release, and Neuronal Endurance. Physiol Rev 2017; 97:1431-1468. [PMID: 28904001 PMCID: PMC6151494 DOI: 10.1152/physrev.00002.2017] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/24/2017] [Accepted: 05/05/2017] [Indexed: 12/11/2022] Open
Abstract
The intrinsic electrical characteristics of different types of neurons are shaped by the K+ channels they express. From among the more than 70 different K+ channel genes expressed in neurons, Kv3 family voltage-dependent K+ channels are uniquely associated with the ability of certain neurons to fire action potentials and to release neurotransmitter at high rates of up to 1,000 Hz. In general, the four Kv3 channels Kv3.1-Kv3.4 share the property of activating and deactivating rapidly at potentials more positive than other channels. Each Kv3 channel gene can generate multiple protein isoforms, which contribute to the high-frequency firing of neurons such as auditory brain stem neurons, fast-spiking GABAergic interneurons, and Purkinje cells of the cerebellum, and to regulation of neurotransmitter release at the terminals of many neurons. The different Kv3 channels have unique expression patterns and biophysical properties and are regulated in different ways by protein kinases. In this review, we cover the function, localization, and modulation of Kv3 channels and describe how levels and properties of the channels are altered by changes in ongoing neuronal activity. We also cover how the protein-protein interaction of these channels with other proteins affects neuronal functions, and how mutations or abnormal regulation of Kv3 channels are associated with neurological disorders such as ataxias, epilepsies, schizophrenia, and Alzheimer's disease.
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Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Yalan Zhang
- Departments of Pharmacology and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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23
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Acute Knockdown of Kv4.1 Regulates Repetitive Firing Rates and Clock Gene Expression in the Suprachiasmatic Nucleus and Daily Rhythms in Locomotor Behavior. eNeuro 2017; 4:eN-NWR-0377-16. [PMID: 28560311 PMCID: PMC5440767 DOI: 10.1523/eneuro.0377-16.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/14/2017] [Accepted: 05/07/2017] [Indexed: 11/23/2022] Open
Abstract
Rapidly activating and inactivating A-type K+ currents (IA) encoded by Kv4.2 and Kv4.3 pore-forming (α) subunits of the Kv4 subfamily are key regulators of neuronal excitability. Previous studies have suggested a role for Kv4.1 α-subunits in regulating the firing properties of mouse suprachiasmatic nucleus (SCN) neurons. To test this, we utilized an RNA-interference strategy to knockdown Kv4.1, acutely and selectively, in the SCN. Current-clamp recordings revealed that the in vivo knockdown of Kv4.1 significantly (p < 0.0001) increased mean ± SEM repetitive firing rates in SCN neurons during the day (6.4 ± 0.5 Hz) and at night (4.3 ± 0.6 Hz), compared with nontargeted shRNA-expressing SCN neurons (day: 3.1 ± 0.5 Hz; night: 1.6 ± 0.3 Hz). IA was also significantly (p < 0.05) reduced in Kv4.1-targeted shRNA-expressing SCN neurons (day: 80.3 ± 11.8 pA/pF; night: 55.3 ± 7.7 pA/pF), compared with nontargeted shRNA-expressing (day: 121.7 ± 10.2 pA/pF; night: 120.6 ± 16.5 pA/pF) SCN neurons. The magnitude of the effect of Kv4.1-targeted shRNA expression on firing rates and IA was larger at night. In addition, Kv4.1-targeted shRNA expression significantly (p < 0.001) increased mean ± SEM nighttime input resistance (Rin; 2256 ± 166 MΩ), compared to nontargeted shRNA-expressing SCN neurons (1143 ± 93 MΩ). Additional experiments revealed that acute knockdown of Kv4.1 significantly (p < 0.01) shortened, by ∼0.5 h, the circadian period of spontaneous electrical activity, clock gene expression and locomotor activity demonstrating a physiological role for Kv4.1-encoded IA channels in regulating circadian rhythms in neuronal excitability and behavior.
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24
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Allen CN, Nitabach MN, Colwell CS. Membrane Currents, Gene Expression, and Circadian Clocks. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a027714. [PMID: 28246182 DOI: 10.1101/cshperspect.a027714] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Neuronal circadian oscillators in the mammalian and Drosophila brain express a circadian clock comprised of interlocking gene transcription feedback loops. The genetic clock regulates the membrane electrical activity by poorly understood signaling pathways to generate a circadian pattern of action potential firing. During the day, Na+ channels contribute an excitatory drive for the spontaneous activity of circadian clock neurons. Multiple types of K+ channels regulate the action potential firing pattern and the nightly reduction in neuronal activity. The membrane electrical activity possibly signaling by changes in intracellular Ca2+ and cyclic adenosine monophosphate (cAMP) regulates the activity of the gene clock. A decline in the signaling pathways that link the gene clock and neural activity during aging and disease may weaken the circadian output and generate significant impacts on human health.
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Affiliation(s)
- Charles N Allen
- Oregon Institute of Occupational Health Sciences and Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239
| | - Michael N Nitabach
- Department of Cellular and Molecular Physiology and Department of Genetics, Yale School of Medicine, New Haven, Connecticut 06520
| | - Christopher S Colwell
- Department of Psychiatry & Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, California 90024
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25
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Quasimodo mediates daily and acute light effects on Drosophila clock neuron excitability. Proc Natl Acad Sci U S A 2016; 113:13486-13491. [PMID: 27821737 DOI: 10.1073/pnas.1606547113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have characterized a light-input pathway regulating Drosophila clock neuron excitability. The molecular clock drives rhythmic electrical excitability of clock neurons, and we show that the recently discovered light-input factor Quasimodo (Qsm) regulates this variation, presumably via an Na+, K+, Cl- cotransporter (NKCC) and the Shaw K+ channel (dKV3.1). Because of light-dependent degradation of the clock protein Timeless (Tim), constant illumination (LL) leads to a breakdown of molecular and behavioral rhythms. Both overexpression (OX) and knockdown (RNAi) of qsm, NKCC, or Shaw led to robust LL rhythmicity. Whole-cell recordings of the large ventral lateral neurons (l-LNv) showed that altering Qsm levels reduced the daily variation in neuronal activity: qsmOX led to a constitutive less active, night-like state, and qsmRNAi led to a more active, day-like state. Qsm also affected daily changes in K+ currents and the GABA reversal potential, suggesting a role in modifying membrane currents and GABA responses in a daily fashion, potentially modulating light arousal and input to the clock. When directly challenged with blue light, wild-type l-LNvs responded with increased firing at night and no net response during the day, whereas altering Qsm, NKKC, or Shaw levels abolished these day/night differences. Finally, coexpression of ShawOX and NKCCRNAi in a qsm mutant background restored LL-induced behavioral arrhythmicity and wild-type neuronal activity patterns, suggesting that the three genes operate in the same pathway. We propose that Qsm affects both daily and acute light effects in l-LNvs probably acting on Shaw and NKCC.
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26
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Farajnia S, Meijer JH, Michel S. Photoperiod Modulates Fast Delayed Rectifier Potassium Currents in the Mammalian Circadian Clock. ASN Neuro 2016; 8:8/5/1759091416670778. [PMID: 27697884 PMCID: PMC5051630 DOI: 10.1177/1759091416670778] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/24/2016] [Indexed: 11/15/2022] Open
Abstract
One feature of the mammalian circadian clock, situated in the suprachiasmatic nucleus (SCN), is its ability to measure day length and thereby contribute to the seasonal adaptation of physiology and behavior. The timing signal from the SCN, namely the 24 hr pattern of electrical activity, is adjusted according to the photoperiod being broader in long days and narrower in short days. Vasoactive intestinal peptide and gamma-aminobutyric acid play a crucial role in intercellular communication within the SCN and contribute to the seasonal changes in phase distribution. However, little is known about the underlying ionic mechanisms of synchronization. The present study was aimed to identify cellular mechanisms involved in seasonal encoding by the SCN. Mice were adapted to long-day (light–dark 16:8) and short-day (light–dark 8:16) photoperiods and membrane properties as well as K+ currents activity of SCN neurons were measured using patch-clamp recordings in acute slices. Remarkably, we found evidence for a photoperiodic effect on the fast delayed rectifier K+ current, that is, the circadian modulation of this ion channel’s activation reversed in long days resulting in 50% higher peak values during the night compared with the unaltered day values. Consistent with fast delayed rectifier enhancement, duration of action potentials during the night was shortened and afterhyperpolarization potentials increased in amplitude and duration. The slow delayed rectifier, transient K+ currents, and membrane excitability were not affected by photoperiod. We conclude that photoperiod can change intrinsic ion channel properties of the SCN neurons, which may influence cellular communication and contribute to photoperiodic phase adjustment.
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Affiliation(s)
- Sahar Farajnia
- Leiden University Medical Center, Leiden, The Netherlands Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | | | - Stephan Michel
- Leiden University Medical Center, Leiden, The Netherlands
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An integrative study identifies KCNC2 as a novel predisposing factor for childhood obesity and the risk of diabetes in the Korean population. Sci Rep 2016; 6:33043. [PMID: 27623749 PMCID: PMC5022012 DOI: 10.1038/srep33043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 08/10/2016] [Indexed: 12/22/2022] Open
Abstract
Obesity is a major risk factor for type 2 diabetes. To unravel the genetic determinants of obesity-associated diabetes, we performed a genome-wide study using the 1,000 Genomes-based imputation in a Korean childhood cohort (KoCAS-1, n = 484) and carried out de novo replication in an independent population (KoCAS-2, n = 1,548). A novel variant (rs10879834) with multiple diverse associations for obesity-related traits was also found to be replicated in an adult cohort (KARE, n = 8,842). Functional annotations using integrative epigenetic analyses identified biological significance and regulatory effects with an inverse methylation-expression correlation (cg27154343 in the 5′-UTR of the KCNC2 gene), tissue-specific enhancer mark (H3K4me1), and pathway enrichment (insulin signaling). Further functional studies in cellular and mouse models demonstrated that KCNC2 is associated with anti-obesogenic effects in the regulation of obesity-induced insulin resistance. KCNC2 shRNA transfection induced endoplasmic reticulum (ER) stress and hepatic gluconeogenesis. Overproduction of KCNC2 decreased ER stress, and treatment with metformin enhanced KCNC2 expression. Taken together, these data suggest that reduction of KCNC2 is associated with modified hepatic gluconeogenesis and increased ER stress on obesity-mediated diabetic risk. An integrative multi-omics analysis might reveal new functional and clinical implications related to the control of energy and metabolic homeostasis in humans.
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Jones JR, McMahon DG. The core clock gene Per1 phases molecular and electrical circadian rhythms in SCN neurons. PeerJ 2016; 4:e2297. [PMID: 27602274 PMCID: PMC4991845 DOI: 10.7717/peerj.2297] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/06/2016] [Indexed: 11/20/2022] Open
Abstract
The brain’s biological clock, the suprachiasmatic nucleus (SCN), exhibits endogenous 24-hour rhythms in gene expression and spontaneous firing rate; however, the functional relationship between these neuronal rhythms is not fully understood. Here, we used a Per1::GFP transgenic mouse line that allows for the simultaneous quantification of molecular clock state and firing rate in SCN neurons to examine the relationship between these key components of the circadian clock. We find that there is a stable, phased relationship between E-box-driven clock gene expression and spontaneous firing rate in SCN neurons and that these relationships are independent of light input onto the system or of GABAA receptor-mediated synaptic activity. Importantly, the concordant phasing of gene and neural rhythms is disrupted in the absence of the homologous clock gene Per1, but persists in the absence of the core clock gene Per2. These results suggest that Per1 plays a unique, non-redundant role in phasing gene expression and firing rate rhythms in SCN neurons to increase the robustness of cellular timekeeping.
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Affiliation(s)
- Jeff R Jones
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, United States; Current affiliation: Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Douglas G McMahon
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, United States; Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
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Abstract
Large conductance Ca(2+)- and voltage-activated K(+) (BK) channels are widely distributed in the postnatal central nervous system (CNS). BK channels play a pleiotropic role in regulating the activity of brain and spinal cord neural circuits by providing a negative feedback mechanism for local increases in intracellular Ca(2+) concentrations. In neurons, they regulate the timing and duration of K(+) influx such that they can either increase or decrease firing depending on the cellular context, and they can suppress neurotransmitter release from presynaptic terminals. In addition, BK channels located in astrocytes and arterial myocytes modulate cerebral blood flow. Not surprisingly, both loss and gain of BK channel function have been associated with CNS disorders such as epilepsy, ataxia, mental retardation, and chronic pain. On the other hand, the neuroprotective role played by BK channels in a number of pathological situations could potentially be leveraged to correct neurological dysfunction.
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Flourakis M, Kula-Eversole E, Hutchison AL, Han TH, Aranda K, Moose DL, White KP, Dinner AR, Lear BC, Ren D, Diekman CO, Raman IM, Allada R. A Conserved Bicycle Model for Circadian Clock Control of Membrane Excitability. Cell 2016; 162:836-48. [PMID: 26276633 DOI: 10.1016/j.cell.2015.07.036] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 05/17/2015] [Accepted: 07/06/2015] [Indexed: 01/04/2023]
Abstract
Circadian clocks regulate membrane excitability in master pacemaker neurons to control daily rhythms of sleep and wake. Here, we find that two distinctly timed electrical drives collaborate to impose rhythmicity on Drosophila clock neurons. In the morning, a voltage-independent sodium conductance via the NA/NALCN ion channel depolarizes these neurons. This current is driven by the rhythmic expression of NCA localization factor-1, linking the molecular clock to ion channel function. In the evening, basal potassium currents peak to silence clock neurons. Remarkably, daily antiphase cycles of sodium and potassium currents also drive mouse clock neuron rhythms. Thus, we reveal an evolutionarily ancient strategy for the neural mechanisms that govern daily sleep and wake.
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Affiliation(s)
- Matthieu Flourakis
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | | | - Alan L Hutchison
- Medical Scientist Training Program, James Franck Institute, Department of Chemistry, Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Tae Hee Han
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Kimberly Aranda
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Devon L Moose
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Kevin P White
- Institute for Genomics and Systems Biology, University of Chicago, Chicago, IL 60637, USA
| | - Aaron R Dinner
- Medical Scientist Training Program, James Franck Institute, Department of Chemistry, Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Bridget C Lear
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Casey O Diekman
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Indira M Raman
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Ravi Allada
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.
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Hermanstyne TO, Simms CL, Carrasquillo Y, Herzog ED, Nerbonne JM. Distinct Firing Properties of Vasoactive Intestinal Peptide-Expressing Neurons in the Suprachiasmatic Nucleus. J Biol Rhythms 2015; 31:57-67. [PMID: 26712166 DOI: 10.1177/0748730415619745] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The suprachiasmatic nucleus (SCN) regulates daily rhythms in physiology and behavior. Previous studies suggest a critical role for neurons expressing vasoactive intestinal peptide (VIP) in coordinating rhythmicity and synchronization in the SCN. Here we examined the firing properties of VIP-expressing SCN neurons in acute brain slices. Active and passive membrane properties were measured in VIP and in non-VIP neurons during the day and at night. Current-clamp recordings revealed that both VIP and non-VIP neurons were spontaneously active, with higher firing rates during the day than at night. Average firing frequencies, however, were higher in VIP neurons (3.1 ± 0.2 Hz, day and 2.4 ± 0.2 Hz, night) than in non-VIP neurons (1.8 ± 0.2 Hz, day and 0.9 ± 0.2 Hz, night), both day and night. The waveforms of individual action potentials in VIP and non-VIP neurons were also distinct. Action potential durations (APD50) were shorter in VIP neurons (3.6 ± 0.1 ms, day and 2.9 ± 0.1 ms, night) than in non-VIP neurons (4.4 ± 0.3 ms, day and 3.5 ± 0.2 ms, night) throughout the light-dark cycle. In addition, afterhyperpolarization (AHP) amplitudes were larger in VIP neurons (21 ± 0.8 mV, day and 24.9 ± 0.9 mV, night) than in non-VIP neurons (17.2 ± 1.1 mV, day and 20.5 ± 1.2 mV, night) during the day and at night. Furthermore, significant day/night differences were observed in APD50 and AHP amplitudes in both VIP and non-VIP SCN neurons, consistent with rhythmic changes in ionic conductances that contribute to shaping the firing properties of both cell types. The higher day and night firing rates of VIP neurons likely contribute to synchronizing electrical activity in the SCN.
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Affiliation(s)
- Tracey O Hermanstyne
- Departments of Developmental Biology and Medicine, Washington University School of Medicine, Saint Louis, MO
| | - Carrie L Simms
- Department of Biology, Washington University, St. Louis, MO
| | - Yarimar Carrasquillo
- Departments of Developmental Biology and Medicine, Washington University School of Medicine, Saint Louis, MO National Center for Complementary and Alternative Medicine, NIH 35 Convent Drive Building 35A, Room 1E-410, Bethesda, MD 20892, USA
| | - Erik D Herzog
- Department of Biology, Washington University, St. Louis, MO
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Medicine, Washington University School of Medicine, Saint Louis, MO
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Kudo T, Block GD, Colwell CS. The Circadian Clock Gene Period1 Connects the Molecular Clock to Neural Activity in the Suprachiasmatic Nucleus. ASN Neuro 2015; 7:7/6/1759091415610761. [PMID: 26553726 PMCID: PMC4710129 DOI: 10.1177/1759091415610761] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The neural activity patterns of suprachiasmatic nucleus (SCN) neurons are dynamically regulated throughout the circadian cycle with highest levels of spontaneous action potentials during the day. These rhythms in electrical activity are critical for the function of the circadian timing system and yet the mechanisms by which the molecular clockwork drives changes in the membrane are not well understood. In this study, we sought to examine how the clock gene Period1 (Per1) regulates the electrical activity in the mouse SCN by transiently and selectively decreasing levels of PER1 through use of an antisense oligodeoxynucleotide. We found that this treatment effectively reduced SCN neural activity. Direct current injection to restore the normal membrane potential partially, but not completely, returned firing rate to normal levels. The antisense treatment also reduced baseline [Ca2+]i levels as measured by Fura2 imaging technique. Whole cell patch clamp recording techniques were used to examine which specific potassium currents were altered by the treatment. These recordings revealed that the large conductance [Ca2+]i-activated potassium currents were reduced in antisense-treated neurons and that blocking this current mimicked the effects of the anti-sense on SCN firing rate. These results indicate that the circadian clock gene Per1 alters firing rate in SCN neurons and raise the possibility that the large conductance [Ca2+]i-activated channel is one of the targets.
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Affiliation(s)
- Takashi Kudo
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA
| | - Gene D Block
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA
| | - Christopher S Colwell
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA
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Granados-Fuentes D, Hermanstyne TO, Carrasquillo Y, Nerbonne JM, Herzog ED. IA Channels Encoded by Kv1.4 and Kv4.2 Regulate Circadian Period of PER2 Expression in the Suprachiasmatic Nucleus. J Biol Rhythms 2015; 30:396-407. [PMID: 26152125 DOI: 10.1177/0748730415593377] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Neurons in the suprachiasmatic nucleus (SCN), the master circadian pacemaker in mammals, display daily rhythms in electrical activity with more depolarized resting potentials and higher firing rates during the day than at night. Although these daily variations in the electrical properties of SCN neurons are required for circadian rhythms in physiology and behavior, the mechanisms linking changes in neuronal excitability to the molecular clock are not known. Recently, we reported that mice deficient for either Kcna4 (Kv1.4(-/-)) or Kcnd2 (Kv4.2(-/-); but not Kcnd3, Kv4.3(-/-)), voltage-gated K(+) (Kv) channel pore-forming subunits that encode subthreshold, rapidly activating, and inactivating K(+) currents (IA), have shortened (0.5 h) circadian periods in SCN firing and in locomotor activity compared with wild-type (WT) mice. In the experiments here, we used a mouse (Per2(Luc)) line engineered with a bioluminescent reporter construct, PERIOD2::LUCIFERASE (PER2::LUC), replacing the endogenous Per2 locus, to test the hypothesis that the loss of Kv1.4- or Kv4.2-encoded IA channels also modifies circadian rhythms in the expression of the clock protein PERIOD2 (PER2). We found that SCN explants from Kv1.4(-/-)Per2(Luc) and Kv4.2(-/-) Per2(Luc), but not Kv4.3(-/-)Per2(Luc), mice have significantly shorter (by approximately 0.5 h) circadian periods in PER2 rhythms, compared with explants from Per2(Luc) mice, revealing that the membrane properties of SCN neurons feedback to regulate clock (PER2) expression. The combined loss of both Kv1.4- and Kv4.2-encoded IA channels in Kv1.4(-/-)/Kv4.2(-/-)Per2(Luc) SCN explants did not result in any further alterations in PER2 rhythms. Interestingly, however, mice lacking both Kv1.4 and Kv4.2 show a striking (approximately 1.8 h) advance in their daily activity onset in a light cycle compared with WT mice, suggesting additional roles for Kv1.4- and Kv4.2-encoded IA channels in controlling the light-dependent responses of neurons within and/or outside of the SCN to regulate circadian phase of daily activity.
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Affiliation(s)
| | - Tracey O Hermanstyne
- Department of Biology, Washington University, St. Louis, MO, USA Departments of Medicine and Developmental Biology, Washington University, St. Louis, MO, USA
| | - Yarimar Carrasquillo
- Departments of Medicine and Developmental Biology, Washington University, St. Louis, MO, USA
| | - Jeanne M Nerbonne
- Departments of Medicine and Developmental Biology, Washington University, St. Louis, MO, USA
| | - Erik D Herzog
- Department of Biology, Washington University, St. Louis, MO, USA
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Vasoactive intestinal polypeptide (VIP)-expressing neurons in the suprachiasmatic nucleus provide sparse GABAergic outputs to local neurons with circadian regulation occurring distal to the opening of postsynaptic GABAA ionotropic receptors. J Neurosci 2015; 35:1905-20. [PMID: 25653351 DOI: 10.1523/jneurosci.2661-14.2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
GABAergic synaptic transmission plays an important role in resetting and synchronizing circadian rhythms in the suprachiasmatic nucleus (SCN). Although the circadian modulation of intrinsic membrane currents and biochemical signaling have been examined in the SCN, the modulation of specific synaptic pathways within the SCN is unexplored. In addition, little is known about the functional properties of these pathways, including which ones involve GABAA receptors (GABAA-Rs). In brain slices obtained from mice, we examined synaptic responses originating from the SCN neurons expressing vasoactive intestinal peptide (VIP+ neurons). Focusing on the local projection within the ventromedial SCN, we found that VIP+ afferents provided input onto 49% of neurons with a preference for VIP-negative (VIP-) neurons. Responses were mediated by GABAA-Rs. The projection was sparsely connected and preferentially targeted a subset of SCN neurons unrelated to postsynaptic VIP expression. For most aspects of VIP+ network output, there was no circadian regulation. Excitability and spontaneous firing of the presynaptic VIP+ neurons were unchanged between day and night, and their network connectivity and synaptic function up through the evoked synaptic conductance were also unchanged. On the other hand, VIP+ input onto VIP- neurons became less inhibitory at night suggesting a postsynaptic alteration in the coupling of GABAA-R conductances to action potential firing. These data suggest that components of the VIP network and its synaptic output up through GABAA-R opening are invariant during the circadian cycle, but the effect on action potential firing is modulated by postsynaptic processes occurring after GABAA-R channel opening.
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35
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Meijer JH, Michel S. Neurophysiological Analysis of the Suprachiasmatic Nucleus. Methods Enzymol 2015; 552:75-102. [DOI: 10.1016/bs.mie.2014.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Archer NP, Wilkinson AV, Ranjit N, Wang J, Zhao H, Swann AC, Shete S. Genetic, psychosocial, and demographic factors associated with social disinhibition in Mexican-origin youth. Brain Behav 2014; 4:521-30. [PMID: 25161819 PMCID: PMC4128034 DOI: 10.1002/brb3.236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 04/21/2014] [Indexed: 12/30/2022] Open
Abstract
INTRODUCTION The genetic heritability for sensation-seeking tendencies ranges from 40 to 60%. Sensation-seeking behaviors typically manifest during adolescence and are associated with alcohol and cigarette experimentation in adolescents. Social disinhibition is an aspect of sensation-seeking that is closely tied to cigarette and alcohol experimentation. METHODS We examined the contribution of candidate genes to social disinhibition among 1132 Mexican origin youth in Houston, Texas, adjusting for established demographic and psychosocial risk factors. Saliva samples were obtained at baseline in 2005-06, and social disinhibition and other psychosocial data were obtained in 2008-09. Participants were genotyped for 672 functional and tagging SNPs potentially related to sensation-seeking, risk-taking, smoking, and alcohol use. RESULTS Six SNPs were significantly associated with social disinhibition scores, after controlling for false discovery and adjusting for population stratification and relevant demographic/psychosocial characteristics. Minor alleles for three of the SNPs (rs1998220 on OPRM1; rs9534511 on HTR2A; and rs4938056 on HTR3B) were associated with increased risk of social disinhibition, while minor alleles for the other three SNPs (rs1003921 on KCNC1; rs16116 downstream of NPY; and rs16870286 on LINC00518) exhibited a protective effect. Age, linguistic acculturation, thrill and adventure-seeking, and drug and alcohol-seeking were all significantly positively associated with increased risk of social disinhibition in a multivariable model (P < 0.001). CONCLUSIONS These results add to our knowledge of genetic risk factors for social disinhibition. Additional research is needed to verify whether these SNPs are associated with social disinhibition among youth of different ethnicities and nationalities, and to elucidate whether and how these SNPs functionally contribute to social disinhibition.
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Affiliation(s)
- Natalie P Archer
- Environmental Epidemiology and Disease Registries Section, Texas Department of State Health Services Austin, Texas
| | - Anna V Wilkinson
- Austin Regional Campus, University of Texas School of Public Health Austin, Texas
| | - Nalini Ranjit
- Austin Regional Campus, University of Texas School of Public Health Austin, Texas
| | - Jian Wang
- Department of Biostatistics, University of Texas M.D. Anderson Cancer Center Houston, Texas
| | - Hua Zhao
- Department of Epidemiology, University of Texas M.D. Anderson Cancer Center Houston, Texas
| | - Alan C Swann
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine One Baylor Plaza, BCM 350, Houston, Texas
| | - Sanjay Shete
- Department of Biostatistics, University of Texas M.D. Anderson Cancer Center Houston, Texas
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Circadian dysfunction in response to in vivo treatment with the mitochondrial toxin 3-nitropropionic acid. ASN Neuro 2014; 6:e00133. [PMID: 24328694 PMCID: PMC3891360 DOI: 10.1042/an20130042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sleep disorders are common in neurodegenerative diseases including Huntington's disease (HD) and develop early in the disease process. Mitochondrial alterations are believed to play a critical role in the pathophysiology of neurodegenerative diseases. In the present study, we evaluated the circadian system of mice after inhibiting mitochondrial complex II of the respiratory chain with the toxin 3-nitropropionic acid (3-NP). We found that a subset of mice treated with low doses of 3-NP exhibited severe circadian deficit in behavior. The temporal patterning of sleep behavior is also disrupted in some mice with evidence of difficulty in the initiation of sleep behavior. Using the open field test during the normal sleep phase, we found that the 3-NP-treated mice were hyperactive. The molecular clockwork responsible for the generation of circadian rhythms as measured by PER2::LUCIFERASE was disrupted in a subset of mice. Within the SCN, the 3-NP treatment resulted in a reduction in daytime firing rate in the subset of mice which had a behavioral deficit. Anatomically, we confirmed that all of the treated mice showed evidence for cell loss within the striatum but we did not see evidence for gross SCN pathology. Together, the data demonstrates that chronic treatment with low doses of the mitochondrial toxin 3-NP produced circadian deficits in a subset of treated mice. This work does raise the possibility that the neural damage produced by mitochondrial dysfunction can contribute to the sleep/circadian dysfunction seen so commonly in neurodegenerative diseases.
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Kudo T, Tahara Y, Gamble KL, McMahon DG, Block GD, Colwell CS. Vasoactive intestinal peptide produces long-lasting changes in neural activity in the suprachiasmatic nucleus. J Neurophysiol 2013; 110:1097-106. [PMID: 23741043 DOI: 10.1152/jn.00114.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The neuropeptide vasoactive intestinal peptide (VIP) is expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN). While VIP is known to be important to the input and output pathways from the SCN, the physiological effects of VIP on electrical activity of SCN neurons are not well known. Here the impact of VIP on firing rate of SCN neurons was investigated in mouse slice cultures recorded during the night. The application of VIP produced an increase in electrical activity in SCN slices that lasted several hours after treatment. This is a novel mechanism by which this peptide can produce long-term changes in central nervous system physiology. The increase in action potential frequency was blocked by a VIP receptor antagonist and lost in a VIP receptor knockout mouse. In addition, inhibitors of both the Epac family of cAMP binding proteins and cAMP-dependent protein kinase (PKA) blocked the induction by VIP. The persistent increase in spike rate following VIP application was not seen in SCN neurons from mice deficient in Kv3 channel proteins and was dependent on the clock protein PER1. These findings suggest that VIP regulates the long-term firing rate of SCN neurons through a VIPR2-mediated increase in the cAMP pathway and implicate the fast delayed rectifier (FDR) potassium currents as one of the targets of this regulation.
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Affiliation(s)
- Takashi Kudo
- Laboratory of Circadian and Sleep Medicine, Department of Psychiatry and Biobehavioral Sciences, University of California-Los Angeles, CA 90024, USA
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Willison LD, Kudo T, Loh DH, Kuljis D, Colwell CS. Circadian dysfunction may be a key component of the non-motor symptoms of Parkinson's disease: insights from a transgenic mouse model. Exp Neurol 2013; 243:57-66. [PMID: 23353924 PMCID: PMC3994881 DOI: 10.1016/j.expneurol.2013.01.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 12/20/2012] [Accepted: 01/15/2013] [Indexed: 01/09/2023]
Abstract
Sleep disorders are nearly ubiquitous among patients with Parkinson's disease (PD), and they manifest early in the disease process. While there are a number of possible mechanisms underlying these sleep disturbances, a primary dysfunction of the circadian system should be considered as a contributing factor. Our laboratory's behavioral phenotyping of a well-validated transgenic mouse model of PD reveals that the electrical activity of neurons within the master pacemaker of the circadian system, the suprachiasmatic nuclei (SCN), is already disrupted at the onset of motor symptoms, although the core features of the intrinsic molecular oscillations in the SCN remain functional. Our observations suggest that the fundamental circadian deficit in these mice lies in the signaling output from the SCN, which may be caused by known mechanisms in PD etiology: oxidative stress and mitochondrial disruption. Disruption of the circadian system is expected to have pervasive effects throughout the body and may itself lead to neurological and cardiovascular disorders. In fact, there is much overlap in the non-motor symptoms experienced by PD patients and in the consequences of circadian disruption. This raises the possibility that the sleep and circadian dysfunction experienced by PD patients may not merely be a subsidiary of the motor symptoms, but an integral part of the disease. Furthermore, we speculate that circadian dysfunction can even accelerate the pathology underlying PD. If these hypotheses are correct, more aggressive treatment of the circadian misalignment and sleep disruptions in PD patients early in the pathogenesis of the disease may be powerful positive modulators of disease progression and patient quality of life.
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Affiliation(s)
- L David Willison
- Division of Child and Adolescent Psychiatry, Laboratory of Circadian and Sleep Medicine, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, CA, USA
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Ruben M, Drapeau MD, Mizrak D, Blau J. A mechanism for circadian control of pacemaker neuron excitability. J Biol Rhythms 2013; 27:353-64. [PMID: 23010658 DOI: 10.1177/0748730412455918] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although the intracellular molecular clocks that regulate circadian (~24 h) behavioral rhythms are well understood, it remains unclear how molecular clock information is transduced into rhythmic neuronal activity that in turn drives behavioral rhythms. To identify potential clock outputs, the authors generated expression profiles from a homogeneous population of purified pacemaker neurons (LN(v)s) from wild-type and clock mutant Drosophila. They identified a group of genes with enriched expression in LN(v)s and a second group of genes rhythmically expressed in LN(v)s in a clock-dependent manner. Only 10 genes fell into both groups: 4 core clock genes, including period (per) and timeless (tim), and 6 genes previously unstudied in circadian rhythms. The authors focused on one of these 6 genes, Ir, which encodes an inward rectifier K(+) channel likely to regulate resting membrane potential, whose expression peaks around dusk. Reducing Ir expression in LN(v)s increased larval light avoidance and lengthened the period of adult locomotor rhythms, consistent with increased LN(v) excitability. In contrast, increased Ir expression made many adult flies arrhythmic and dampened PER protein oscillations. The authors propose that rhythmic Ir expression contributes to daily rhythms in LN(v) neuronal activity, which in turn feed back to regulate molecular clock oscillations.
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Affiliation(s)
- Marc Ruben
- Department of Biology, New York University, New York, NY 10003, USA
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Montgomery JR, Whitt JP, Wright BN, Lai MH, Meredith AL. Mis-expression of the BK K(+) channel disrupts suprachiasmatic nucleus circuit rhythmicity and alters clock-controlled behavior. Am J Physiol Cell Physiol 2012; 304:C299-311. [PMID: 23174562 DOI: 10.1152/ajpcell.00302.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In mammals, almost all aspects of circadian rhythmicity are attributed to activity in a discrete neural circuit of the hypothalamus, the suprachiasmatic nucleus (SCN). A 24-h rhythm in spontaneous firing is the fundamental neural intermediary to circadian behavior, but the ionic mechanisms that pattern circuit rhythmicity, and the integrated impact on behavior, are not well studied. Here, we demonstrate that daily modulation of a major component of the nighttime-phased suppressive K(+) current, encoded by the BK Ca(2+)-activated K(+) current channel (K(Ca)1.1 or Kcnma1), is a critical arbiter of circadian rhythmicity in the SCN circuit. Aberrant induction of BK current during the day in transgenic mice using a Per1 promoter (Tg-BK(R207Q)) reduced SCN firing or silenced neurons, decreasing the circadian amplitude of the ensemble circuit rhythm. Changes in cellular and circuit excitability in Tg-BK(R207Q) SCNs were correlated with elongated behavioral active periods and enhanced responses to phase-shifting stimuli. Unexpectedly, despite the severe reduction in circuit amplitude, circadian behavioral amplitudes in Tg-BK(R207Q) mice were relatively normal. These data demonstrate that downregulation of the BK current during the day is essential for the high amplitude neural activity pattern in the SCN that restricts locomotor activity to the appropriate phase and maintains the clock's robustness against perturbation. However, a residually rhythmic subset prevails over the ensemble circuit to drive the fundamental circadian behavioral rhythm.
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Affiliation(s)
- Jenna R Montgomery
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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I(A) channels encoded by Kv1.4 and Kv4.2 regulate neuronal firing in the suprachiasmatic nucleus and circadian rhythms in locomotor activity. J Neurosci 2012; 32:10045-52. [PMID: 22815518 DOI: 10.1523/jneurosci.0174-12.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurons in the suprachiasmatic nucleus (SCN) display coordinated circadian changes in electrical activity that are critical for daily rhythms in physiology, metabolism, and behavior. SCN neurons depolarize spontaneously and fire repetitively during the day and hyperpolarize, drastically reducing firing rates, at night. To explore the hypothesis that rapidly activating and inactivating A-type (I(A)) voltage-gated K(+) (Kv) channels, which are also active at subthreshold membrane potentials, are critical regulators of the excitability of SCN neurons, we examined locomotor activity and SCN firing in mice lacking Kv1.4 (Kv1.4(-/-)), Kv4.2 (Kv4.2(-/-)), or Kv4.3 (Kv4.3(-/-)), the pore-forming (α) subunits of I(A) channels. Mice lacking either Kv1.4 or Kv4.2 α subunits have markedly shorter (0.5 h) periods of locomotor activity than wild-type (WT) mice. In vitro extracellular multi-electrode recordings revealed that Kv1.4(-/-) and Kv4.2(-/-) SCN neurons display circadian rhythms in repetitive firing, but with shorter periods (0.5 h) than WT cells. In contrast, the periods of wheel-running activity in Kv4.3(-/-) mice and firing in Kv4.3(-/-) SCN neurons were indistinguishable from WT animals and neurons. Quantitative real-time PCR revealed that the transcripts encoding all three Kv channel α subunits, Kv1.4, Kv4.2, and Kv4.3, are expressed constitutively throughout the day and night in the SCN. Together, these results demonstrate that Kv1.4- and Kv4.2-encoded I(A) channels regulate the intrinsic excitability of SCN neurons during the day and night and determine the period and amplitude of circadian rhythms in SCN neuron firing and locomotor behavior.
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Punia S, Rumery KK, Yu EA, Lambert CM, Notkins AL, Weaver DR. Disruption of gene expression rhythms in mice lacking secretory vesicle proteins IA-2 and IA-2β. Am J Physiol Endocrinol Metab 2012; 303:E762-76. [PMID: 22785238 PMCID: PMC3468428 DOI: 10.1152/ajpendo.00513.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulinoma-associated protein (IA)-2 and IA-2β are transmembrane proteins involved in neurotransmitter secretion. Mice with targeted disruption of both IA-2 and IA-2β (double-knockout, or DKO mice) have numerous endocrine and physiological disruptions, including disruption of circadian and diurnal rhythms. In the present study, we have assessed the impact of disruption of IA-2 and IA-2β on molecular rhythms in the brain and peripheral oscillators. We used in situ hybridization to assess molecular rhythms in the hypothalamic suprachiasmatic nuclei (SCN) of wild-type (WT) and DKO mice. The results indicate significant disruption of molecular rhythmicity in the SCN, which serves as the central pacemaker regulating circadian behavior. We also used quantitative PCR to assess gene expression rhythms in peripheral tissues of DKO, single-knockout, and WT mice. The results indicate significant attenuation of gene expression rhythms in several peripheral tissues of DKO mice but not in either single knockout. To distinguish whether this reduction in rhythmicity reflects defective oscillatory function in peripheral tissues or lack of entrainment of peripheral tissues, animals were injected with dexamethasone daily for 15 days, and then molecular rhythms were assessed throughout the day after discontinuation of injections. Dexamethasone injections improved gene expression rhythms in liver and heart of DKO mice. These results are consistent with the hypothesis that peripheral tissues of DKO mice have a functioning circadian clockwork, but rhythmicity is greatly reduced in the absence of robust, rhythmic physiological signals originating from the SCN. Thus, IA-2 and IA-2β play an important role in the regulation of circadian rhythms, likely through their participation in neurochemical communication among SCN neurons.
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Affiliation(s)
- Sohan Punia
- Experimental Medicine Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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Na(V)1.1 channels are critical for intercellular communication in the suprachiasmatic nucleus and for normal circadian rhythms. Proc Natl Acad Sci U S A 2012; 109:E368-77. [PMID: 22223655 DOI: 10.1073/pnas.1115729109] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Na(V)1.1 is the primary voltage-gated Na(+) channel in several classes of GABAergic interneurons, and its reduced activity leads to reduced excitability and decreased GABAergic tone. Here, we show that Na(V)1.1 channels are expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus. Mice carrying a heterozygous loss of function mutation in the Scn1a gene (Scn1a(+/-)), which encodes the pore-forming α-subunit of the Na(V)1.1 channel, have longer circadian period than WT mice and lack light-induced phase shifts. In contrast, Scn1a(+/-) mice have exaggerated light-induced negative-masking behavior and normal electroretinogram, suggesting an intact retina light response. Scn1a(+/-) mice show normal light induction of c-Fos and mPer1 mRNA in ventral SCN but impaired gene expression responses in dorsal SCN. Electrical stimulation of the optic chiasm elicits reduced calcium transients and impaired ventro-dorsal communication in SCN neurons from Scn1a(+/-) mice, and this communication is barely detectable in the homozygous gene KO (Scn1a(-/-)). Enhancement of GABAergic transmission with tiagabine plus clonazepam partially rescues the effects of deletion of Na(V)1.1 on circadian period and phase shifting. Our report demonstrates that a specific voltage-gated Na(+) channel and its associated impairment of SCN interneuronal communication lead to major deficits in the function of the master circadian pacemaker. Heterozygous loss of Na(V)1.1 channels is the underlying cause for severe myoclonic epilepsy of infancy; the circadian deficits that we report may contribute to sleep disorders in severe myoclonic epilepsy of infancy patients.
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Abstract
Neurons in the suprachiasmatic nucleus (SCN) function as part of a central timing circuit that drives daily changes in our behaviour and underlying physiology. A hallmark feature of SCN neuronal populations is that they are mostly electrically silent during the night, start to fire action potentials near dawn and then continue to generate action potentials with a slow and steady pace all day long. Sets of currents are responsible for this daily rhythm, with the strongest evidence for persistent Na(+) currents, L-type Ca(2+) currents, hyperpolarization-activated currents (I(H)), large-conductance Ca(2+) activated K(+) (BK) currents and fast delayed rectifier (FDR) K(+) currents. These rhythms in electrical activity are crucial for the function of the circadian timing system, including the expression of clock genes, and decline with ageing and disease. This article reviews our current understanding of the ionic and molecular mechanisms that drive the rhythmic firing patterns in the SCN.
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Affiliation(s)
- Christopher S Colwell
- Laboratory of Circadian and Sleep Medicine, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California Los Angeles, California 90024, USA.
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Pantazopoulos H, Dolatshad H, Davis FC. A fear-inducing odor alters PER2 and c-Fos expression in brain regions involved in fear memory. PLoS One 2011; 6:e20658. [PMID: 21655193 PMCID: PMC3105109 DOI: 10.1371/journal.pone.0020658] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 05/06/2011] [Indexed: 12/04/2022] Open
Abstract
Evidence demonstrates that rodents learn to associate a foot shock with time of day, indicating the formation of a fear related time-stamp memory, even in the absence of a functioning SCN. In addition, mice acquire and retain fear memory better during the early day compared to the early night. This type of memory may be regulated by circadian pacemakers outside of the SCN. As a first step in testing the hypothesis that clock genes are involved in the formation of a time-stamp fear memory, we exposed one group of mice to fox feces derived odor (TMT) at ZT 0 and one group at ZT 12 for 4 successive days. A separate group with no exposure to TMT was also included as a control. Animals were sacrificed one day after the last exposure to TMT, and PER2 and c-Fos protein were quantified in the SCN, amygdala, hippocampus, and piriform cortex. Exposure to TMT had a strong effect at ZT 0, decreasing PER2 expression at this time point in most regions except the SCN, and reversing the normal rhythm of PER2 expression in the amygdala and piriform cortex. These changes were accompanied by increased c-Fos expression at ZT0. In contrast, exposure to TMT at ZT 12 abolished the rhythm of PER2 expression in the amygdala. In addition, increased c-Fos expression at ZT 12 was only detected in the central nucleus of the amygdala in the TMT12 group. TMT exposure at either time point did not affect PER2 or c-Fos in the SCN, indicating that under a light-dark cycle, the SCN rhythm is stable in the presence of repeated exposure to a fear-inducing stimulus. Taken together, these results indicate that entrainment to a fear-inducing stimulus leads to changes in PER2 and c-Fos expression that are detected 24 hours following the last exposure to TMT, indicating entrainment of endogenous oscillators in these regions. The observed effects on PER2 expression and c-Fos were stronger during the early day than during the early night, possibly to prepare appropriate systems at ZT 0 to respond to a fear-inducing stimulus.
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Affiliation(s)
- Harry Pantazopoulos
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America.
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