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Said EA, Lewis RW, Dallas ML, Peers C, Ross FA, Unciti-Broceta A, Grahame Hardie D, Mark Evans A. The thienopyridine A-769662 and benzimidazole 991 inhibit human TASK-3 potassium channels in an AMPK-independent manner. Biochem Pharmacol 2024:116562. [PMID: 39362502 DOI: 10.1016/j.bcp.2024.116562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 09/24/2024] [Accepted: 09/30/2024] [Indexed: 10/05/2024]
Abstract
Heteromeric Tandem pore domain Acid Sensitive (TASK)-1/3 channels are critical to oxygen-sensing by carotid body type 1 cells, where hypoxia-induced inhibition of TASK-3 and/or TASK-1/3 potassium currents leads to voltage-gated calcium entry, exocytotic transmitter release and increases in carotid body afferent input responses that initiate corrective changes in breathing patterns. It was proposed that, in response to hypoxia, the AMP-activated protein kinase (AMPK) might directly phosphorylate and inhibit TASK channels, in particular TASK-3, but studies on rat type I cells questioned this view. However, sequence alignment identified a putative AMPK recognition motif in human (h) TASK-3, but not hTASK-1, with Ser55 representing a potential phosphorylation site. We therefore studied the effects of five different AMPK activators on recombinant hTASK-3 potassium channels expressed in human embryonic kidney (HEK)-293 cells. Two structurally unrelated AMPK activators, the thienopyridine A-769662 (100-500 µM) and the benzimidazole 991 (3-30 µM) inhibited hTASK-3 currents in a concentration-dependent manner, while the 4-azabenzimidazole MK-8722 (3-30 µM) partially inhibited hTASK-3 at concentrations above those required for maximal AMPK activation. By contrast, the 4-azabenzimidazole, BI-9774 (10-100 µM; a closely related analogue of MK8722) and the pro-drug AICA-riboside (1 mM; metabolised to ZMP, an AMP-mimetic) had no significant effect on hTASK-3 currents at concentrations sufficient to maximally activate AMPK. Importantly, A-769662 (300 µM) also inhibited hTASK-3 channel currents in HEK-293 cells that stably over-expressed an AMPK-β1 subunit mutant (S108A) that renders AMPK insensitive to activators that bind to the Allosteric Drug and Metabolite site, such as A-769662. We therefore identify A-769662 and 991 as novel hTASK-3 channel inhibitors and provide conclusive evidence that AMPK does not regulate hTASK-3 channel currents.
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Affiliation(s)
- Esraa A Said
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Egypt
| | - Ryan W Lewis
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK; School of Pharmacy, University of Reading, Reading RG6 6UB, UK; School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 4HN, UK; Edinburgh Cancer Research, Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Mark L Dallas
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK
| | - Chris Peers
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK; School of Pharmacy, University of Reading, Reading RG6 6UB, UK; School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 4HN, UK; Edinburgh Cancer Research, Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Fiona A Ross
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 4HN, UK
| | - Asier Unciti-Broceta
- Edinburgh Cancer Research, Cancer Research UK Scotland Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - D Grahame Hardie
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 4HN, UK
| | - A Mark Evans
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK.
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2
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Zhang YM, Zong HC, Qi YB, Chang LL, Gao YN, Zhou T, Yin T, Liu M, Pan KJ, Chen WG, Guo HR, Guo F, Peng YM, Wang M, Feng LY, Zang Y, Li Y, Li J. Anxiolytic effect of antidiabetic metformin is mediated by AMPK activation in mPFC inhibitory neurons. Mol Psychiatry 2023; 28:3955-3965. [PMID: 37798418 PMCID: PMC10730396 DOI: 10.1038/s41380-023-02283-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/05/2023] [Accepted: 09/21/2023] [Indexed: 10/07/2023]
Abstract
Diabetic patients receiving the antidiabetic drug metformin have been observed to exhibit a lower prevalence of anxiety disorders, yet the precise mechanism behind this phenomenon is unclear. In our study, we found that anxiety induces a region-specific reduction in AMPK activity in the medial prefrontal cortex (mPFC). Concurrently, transgenic mice with brain-specific AMPK knockout displayed abnormal anxiety-like behaviors. Treatment with metformin or the overexpression of AMPK restored normal AMPK activity in the mPFC and mitigated social stress-induced anxiety-like behaviors. Furthermore, the specific genetic deletion of AMPK in the mPFC not only instigated anxiety in mice but also nullified the anxiolytic effects of metformin. Brain slice recordings revealed that GABAergic excitation and the resulting inhibitory inputs to mPFC pyramidal neurons were selectively diminished in stressed mice. This reduction led to an excitation-inhibition imbalance, which was effectively reversed by metformin treatment or AMPK overexpression. Moreover, the genetic deletion of AMPK in the mPFC resulted in a similar defect in GABAergic inhibitory transmission and a consequent hypo-inhibition of mPFC pyramidal neurons. We also generated a mouse model with AMPK knockout specific to GABAergic neurons. The anxiety-like behaviors in this transgenic mouse demonstrated the unique role of AMPK in the GABAergic system in relation to anxiety. Therefore, our findings suggest that the activation of AMPK in mPFC inhibitory neurons underlies the anxiolytic effects of metformin, highlighting the potential of this primary antidiabetic drug as a therapeutic option for treating anxiety disorders.
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Affiliation(s)
- Yong-Mei Zhang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, 310024, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hai-Chao Zong
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ying-Bei Qi
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, 310024, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Liu-Liu Chang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ya-Nan Gao
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, Jiangsu, 210009, China
| | - Ting Zhou
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tao Yin
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Meng Liu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kai-Jun Pan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, Jiangsu, 210009, China
| | - Wen-Gang Chen
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, Jiangsu, 210009, China
| | - Hao-Ran Guo
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fei Guo
- University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Key Laboratory of Receptor Research, Department of Neuropharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yan-Min Peng
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200025, China
| | - Min Wang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lin-Yin Feng
- University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Key Laboratory of Receptor Research, Department of Neuropharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yi Zang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Lin Gang Laboratory, Shanghai, 200031, China.
| | - Yang Li
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- CAS Key Laboratory of Receptor Research, Department of Neuropharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 200040, China.
| | - Jia Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, 310024, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, Jiangsu, 210009, China.
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan Tsuihang New District, Zhongshan, Guangzhou, 528400, China.
- Drug Discovery Shandong Laboratory, Bohai Rim Advanced Research Institute for Drug Discovery, Yantai, Shandong, 264117, China.
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3
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Schreiber JA, Derksen A, Goerges G, Schütte S, Sörgel J, Kiper AK, Strutz-Seebohm N, Ruck T, Meuth SG, Decher N, Seebohm G. Cloxyquin activates hTRESK by allosteric modulation of the selectivity filter. Commun Biol 2023; 6:745. [PMID: 37464013 PMCID: PMC10354012 DOI: 10.1038/s42003-023-05114-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 07/07/2023] [Indexed: 07/20/2023] Open
Abstract
The TWIK-related spinal cord K+ channel (TRESK, K2P18.1) is a K2P channel contributing to the maintenance of membrane potentials in various cells. Recently, physiological TRESK function was identified as a key player in T-cell differentiation rendering the channel a new pharmacological target for treatment of autoimmune diseases. The channel activator cloxyquin represents a promising lead compound for the development of a new class of immunomodulators. Identification of cloxyquin binding site and characterization of the molecular activation mechanism can foster the future drug development. Here, we identify the cloxyquin binding site at the M2/M4 interface by mutational scan and analyze the molecular mechanism of action by protein modeling as well as in silico and in vitro electrophysiology using different permeating ion species (K+ / Rb+). In combination with kinetic analyses of channel inactivation, our results suggest that cloxyquin allosterically stabilizes the inner selectivity filter facilitating the conduction process subsequently activating hTRESK.
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Affiliation(s)
- Julian Alexander Schreiber
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany.
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany.
| | - Anastasia Derksen
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany
| | - Gunnar Goerges
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
| | - Sven Schütte
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Jasmin Sörgel
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Nathalie Strutz-Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Sven G Meuth
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Münster, Germany
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4
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Lin G, Lin L, Lin H, Chen W, Chen L, Chen X, Chen S, Lin Q, Xu Y, Zeng Y. KCNK3 inhibits proliferation and glucose metabolism of lung adenocarcinoma via activation of AMPK-TXNIP pathway. Cell Death Dis 2022; 8:360. [PMID: 35963847 PMCID: PMC9376064 DOI: 10.1038/s41420-022-01152-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/21/2022] [Accepted: 07/27/2022] [Indexed: 11/09/2022]
Abstract
Non-small cell lung cancer (NSCLC) is a primary histological subtype of lung cancer with increased morbidity and mortality. K+ channels have been revealed to be involved in carcinogenesis in various malignant tumors. However, TWIK-related acid-sensitive potassium channel 1 (TASK-1, also called KCNK3), a genetic member of K2P channels, remains an enigma in lung adenocarcinoma (LUAD). Herein, we investigated the pathological process of KCNK3 in proliferation and glucose metabolism of LUAD. The expressions of KCNK3 in LUAD tissues and corresponding adjacent tissues were identified by RNA sequencing, quantitative real-time polymerase chain reaction, western blot, and immunohistochemistry. Gain and loss-of-function assays were performed to estimate the role of KCNK3 in proliferation and glucose metabolism of LUAD. Additionally, energy metabolites of LUAD cells were identified by targeted metabolomics analysis. The expressions of metabolic molecules and active biomarkers associated with AMPK-TXNIP signaling pathway were detected via western blot and immunofluorescence. KCNK3 was significantly downregulated in LUAD tissues and correlated with patients' poor prognosis. Overexpression of KCNK3 largely regulated the process of oncogenesis and glycometabolism in LUAD in vitro and in vivo. Mechanistic studies found that KCNK3-mediated differential metabolites were mainly enriched in AMPK signaling pathway. Furthermore, rescue experiments demonstrated that KCNK3 suppressed proliferation and glucose metabolism via activation of the AMPK-TXNIP pathway in LUAD cells. In summary, our research highlighted an emerging role of KCNK3 in the proliferative activity and glycometabolism of LUAD, suggesting that KCNK3 may be an optimal predictor for prognosis and a potential therapeutic target of LUAD.
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Affiliation(s)
- Guofu Lin
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China.,The Second Clinical College, Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Lanlan Lin
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China.,The Second Clinical College, Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Hai Lin
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China.,The Second Clinical College, Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Wenhan Chen
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China.,The Second Clinical College, Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Luyang Chen
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China.,The Second Clinical College, Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Xiaohui Chen
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China.,The Second Clinical College, Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Shaohua Chen
- Department of Pathology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China
| | - Qinhui Lin
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China
| | - Yuan Xu
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China. .,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China. .,Clinical Research Unit, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.
| | - Yiming Zeng
- Department of Pulmonary and Critical Care Medicine, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China. .,Respiratory Medicine Center of Fujian Province, Quanzhou, Fujian province, 362000, China. .,Clinical Research Unit, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian province, 362000, China.
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Rueda-Ruzafa L, Herrera-Pérez S, Campos-Ríos A, Lamas JA. Are TREK Channels Temperature Sensors? Front Cell Neurosci 2021; 15:744702. [PMID: 34690704 PMCID: PMC8526543 DOI: 10.3389/fncel.2021.744702] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
Internal human body normal temperature fluctuates between 36.5 and 37.5°C and it is generally measured in the oral cavity. Interestingly, most electrophysiological studies on the functioning of ion channels and their role in neuronal behavior are carried out at room temperature, which usually oscillates between 22 and 24°C, even when thermosensitive channels are studied. We very often forget that if the core of the body reached that temperature, the probability of death from cardiorespiratory arrest would be extremely high. Does this mean that we are studying ion channels in dying neurons? Thousands of electrophysiological experiments carried out at these low temperatures suggest that most neurons tolerate this aggression quite well, at least for the duration of the experiments. This also seems to happen with ion channels, although studies at different temperatures indicate large changes in both, neuron and channel behavior. It is known that many chemical, physical and therefore physiological processes, depend to a great extent on body temperature. Temperature clearly affects the kinetics of numerous events such as chemical reactions or conformational changes in proteins but, what if these proteins constitute ion channels and these channels are specifically designed to detect changes in temperature? In this review, we discuss the importance of the potassium channels of the TREK subfamily, belonging to the recently discovered family of two-pore domain channels, in the transduction of thermal sensitivity in different cell types.
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Affiliation(s)
- Lola Rueda-Ruzafa
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| | - Salvador Herrera-Pérez
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Grupo de Neurofisiología Experimental y Circuitos Neuronales, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
| | - Ana Campos-Ríos
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| | - J A Lamas
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
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Wang S, Dai Y. Roles of AMPK and Its Downstream Signals in Pain Regulation. Life (Basel) 2021; 11:life11080836. [PMID: 34440581 PMCID: PMC8401922 DOI: 10.3390/life11080836] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/06/2021] [Accepted: 08/12/2021] [Indexed: 12/20/2022] Open
Abstract
Pain is an unpleasant sensory and emotional state that decreases quality of life. A metabolic sensor, adenosine monophosphate-activated protein kinase (AMPK), which is ubiquitously expressed in mammalian cells, has recently attracted interest as a new target of pain research. Abnormal AMPK expression and function in the peripheral and central nervous systems are associated with various types of pain. AMPK and its downstream kinases participate in the regulation of neuron excitability, neuroinflammation and axonal and myelin regeneration. Numerous AMPK activators have reduced pain behavior in animal models. The current understanding of pain has been deepened by AMPK research, but certain issues, such as the interactions of AMPK at each step of pain regulation, await further investigation. This review examines the roles of AMPK and its downstream kinases in neurons and non-neuronal cells, as well as their contribution to pain regulation.
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Affiliation(s)
- Shenglan Wang
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing 100029, China
- Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe 650-8530, Japan
- Correspondence: (S.W.); (Y.D.); Tel.: +86-10-53912197 (S.W.); +81-78-304-3147 (Y.D.)
| | - Yi Dai
- Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe 650-8530, Japan
- Traditional Medicine Research Center, Chinese Medicine Confucius Institute, Hyogo College of Medicine, Kobe 663-8501, Japan
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya 663-8501, Japan
- Correspondence: (S.W.); (Y.D.); Tel.: +86-10-53912197 (S.W.); +81-78-304-3147 (Y.D.)
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7
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Mitochondrial Function and Anesthetic Sensitivity in the Mouse Spinal Cord. Anesthesiology 2021; 134:901-914. [PMID: 33909880 DOI: 10.1097/aln.0000000000003794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Ndufs4 knockout (KO) mice are defective in mitochondrial complex I function and hypersensitive to inhibition of spinal cord-mediated response to noxious stimuli by volatile anesthetics. It was hypothesized that, compared to wild-type, synaptic or intrinsic neuronal function is hypersensitive to isoflurane in spinal cord slices from knockout mice. METHODS Neurons from slices of the vestibular nucleus, central medial thalamus, and spinal cord from wild-type and the global Ndufs4 knockout were patch clamped. Unstimulated synaptic and intrinsic neuronal characteristics were measured in response to isoflurane. Norfluoxetine was used to block TREK channel conductance. Cholinergic cells were labeled with tdTomato. RESULTS All values are reported as means and 95% CIs. Spontaneous synaptic activities were not different between the mutant and control. Isoflurane (0.6%; 0.25 mM; Ndufs4[KO] EC95) increased the holding current in knockout (ΔHolding current, 126 pA [95% CI, 99 to 152 pA]; ΔHolding current P < 0.001; n = 21) but not wild-type (ΔHolding current, 2 7 pA [95% CI, 9 to 47 pA]; ΔHolding current, P = 0.030; n = 25) spinal cord slices. Knockout and wild-type ΔHolding currents were significantly different (P < 0.001). Changes comparable to those in the knockout were seen in the wild type only in 1.8% (0.74 mM) isoflurane (ΔHolding current, 72 pA [95% CI, 43 to 97 pA]; ΔHolding current, P < 0.001; n = 13), the control EC95. Blockade of action potentials indicated that the increased holding current in the knockout was not dependent on synaptic input (ΔHolding current, 154 pA [95% CI, 99 to 232 pA]; ΔHolding current, P = 0.506 compared to knockout without blockade; n = 6). Noncholinergic neurons mediated the increase in holding current sensitivity in Ndufs4 knockout. The increased currents were blocked by norfluoxetine. CONCLUSIONS Isoflurane increased an outwardly rectifying potassium current in ventral horn neurons of the Ndufs4(KO) mouse at a concentration much lower than in controls. Noncholinergic neurons in the spinal cord ventral horn mediated the effect. Presynaptic functions in Ndufs4(KO) slices were not hypersensitive to isoflurane. These data link anesthetic sensitivity, mitochondrial function, and postsynaptic channel activity. EDITOR’S PERSPECTIVE
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8
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Iturriaga R, Alcayaga J, Chapleau MW, Somers VK. Carotid body chemoreceptors: physiology, pathology, and implications for health and disease. Physiol Rev 2021; 101:1177-1235. [PMID: 33570461 PMCID: PMC8526340 DOI: 10.1152/physrev.00039.2019] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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Pineda RH, Hypolite J, Lee S, Carrasco A, Iguchi N, Meacham RB, Malykhina AP. Altered detrusor contractility and voiding patterns in mice lacking the mechanosensitive TREK-1 channel. BMC Urol 2019; 19:40. [PMID: 31113422 PMCID: PMC6528348 DOI: 10.1186/s12894-019-0475-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 05/13/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Previously published results from our laboratory identified a mechano-gated two-pore domain potassium channel, TREK-1, as a main mechanosensor in the smooth muscle of the human urinary bladder. One of the limitations of in vitro experiments on isolated human detrusor included inability to evaluate in vivo effects of TREK-1 on voiding function, as the channel is also expressed in the nervous system, and may modulate micturition via neural pathways. Therefore, in the present study, we aimed to assess the role of TREK-1 channel in bladder function and voiding patterns in vivo by using TREK-1 knockout (KO) mice. METHODS Adult C57BL/6 J wild-type (WT, N = 32) and TREK-1 KO (N = 33) mice were used in this study. The overall phenotype and bladder function were evaluated by gene and protein expression of TREK-1 channel, in vitro contractile experiments using detrusor strips in response to stretch and pharmacological stimuli, and cystometry in unanesthetized animals. RESULTS TREK-1 KO animals had an elevated basal muscle tone and enhanced spontaneous activity in the detrusor without detectable changes in bladder morphology/histology. Stretch applied to isolated detrusor strips increased the amplitude of spontaneous contractions by 109% in the TREK-1 KO group in contrast to a 61% increase in WT mice (p ≤ 0.05 to respective baseline for each group). The detrusor strips from TREK-1 KO mice also generated more contractile force in response to electric field stimulation and high potassium concentration in comparison to WT group (p ≤ 0.05 for both tests). However, cystometric recordings from TREK-1 KO mice revealed a significant increase in the duration of the intermicturition interval, enhanced bladder capacity and increased number of non-voiding contractions in comparison to WT mice. CONCLUSIONS Our results provide evidence that global down-regulation of TREK-1 channels has dual effects on detrusor contractility and micturition patterns in vivo. The observed differences are likely due to expression of TREK-1 channel not only in detrusor myocytes but also in afferent and efferent neural pathways involved in regulation of micturition which may underly the "mixed" voiding phenotype in TREK-1 KO mice.
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Affiliation(s)
- Ricardo H Pineda
- Division of Urology, Department of Surgery, University of Colorado Denver,Anschutz Medical Campus, 12700 E 19th Ave, M/S C317, Aurora, CO, 80045, USA
| | - Joseph Hypolite
- Division of Urology, Department of Surgery, University of Colorado Denver,Anschutz Medical Campus, 12700 E 19th Ave, M/S C317, Aurora, CO, 80045, USA
| | - Sanghee Lee
- Department of Urology, University of California San Diego, 3855 Health Science Drive, Room 4345, Bay 4LL, La Jolla, CA, 92093, USA
| | - Alonso Carrasco
- Children's Mercy Hospital, 2401 Gillham Rd, Kansas City, MO, 64108, USA
| | - Nao Iguchi
- Division of Urology, Department of Surgery, University of Colorado Denver,Anschutz Medical Campus, 12700 E 19th Ave, M/S C317, Aurora, CO, 80045, USA
| | - Randall B Meacham
- Division of Urology, Department of Surgery, University of Colorado Denver, Academic Office One Bldg., Rm 5602, 12631 East 17th Ave., M/S C319, Aurora, CO, 80045, USA
| | - Anna P Malykhina
- Division of Urology, Department of Surgery, University of Colorado Denver,Anschutz Medical Campus, 12700 E 19th Ave, M/S C317, Aurora, CO, 80045, USA.
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Lamas JA, Rueda-Ruzafa L, Herrera-Pérez S. Ion Channels and Thermosensitivity: TRP, TREK, or Both? Int J Mol Sci 2019; 20:ijms20102371. [PMID: 31091651 PMCID: PMC6566417 DOI: 10.3390/ijms20102371] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/03/2019] [Accepted: 05/07/2019] [Indexed: 11/16/2022] Open
Abstract
Controlling body temperature is a matter of life or death for most animals, and in mammals the complex thermoregulatory system is comprised of thermoreceptors, thermosensors, and effectors. The activity of thermoreceptors and thermoeffectors has been studied for many years, yet only recently have we begun to obtain a clear picture of the thermosensors and the molecular mechanisms involved in thermosensory reception. An important step in this direction was the discovery of the thermosensitive transient receptor potential (TRP) cationic channels, some of which are activated by increases in temperature and others by a drop in temperature, potentially converting the cells in which they are expressed into heat and cold receptors. More recently, the TWIK-related potassium (TREK) channels were seen to be strongly activated by increases in temperature. Hence, in this review we want to assess the hypothesis that both these groups of channels can collaborate, possibly along with other channels, to generate the wide range of thermal sensations that the nervous system is capable of handling.
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Affiliation(s)
- J Antonio Lamas
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, 36310 Vigo, Spain.
| | - Lola Rueda-Ruzafa
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, 36310 Vigo, Spain.
| | - Salvador Herrera-Pérez
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, 36310 Vigo, Spain.
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Intracellular signaling of the AMP-activated protein kinase. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 116:171-207. [DOI: 10.1016/bs.apcsb.2018.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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12
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Lamas JA, Fernández-Fernández D. Tandem pore TWIK-related potassium channels and neuroprotection. Neural Regen Res 2019; 14:1293-1308. [PMID: 30964046 PMCID: PMC6524494 DOI: 10.4103/1673-5374.253506] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
TWIK-related potassium channels (TREK) belong to a subfamily of the two-pore domain potassium channels family with three members, TREK1, TREK2 and TWIK-related arachidonic acid-activated potassium channels. The two-pore domain potassium channels is the last big family of channels being discovered, therefore it is not surprising that most of the information we know about TREK channels predominantly comes from the study of heterologously expressed channels. Notwithstanding, in this review we pay special attention to the limited amount of information available on native TREK-like channels and real neurons in relation to neuroprotection. Mainly we focus on the role of free fatty acids, lysophospholipids and other neuroprotective agents like riluzole in the modulation of TREK channels, emphasizing on how important this modulation may be for the development of new therapies against neuropathic pain, depression, schizophrenia, epilepsy, ischemia and cardiac complications.
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Affiliation(s)
- J Antonio Lamas
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, Vigo, Galicia, Spain
| | - Diego Fernández-Fernández
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, Vigo, Galicia, Spain
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13
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AMP-Activated Protein Kinase (AMPK)-Dependent Regulation of Renal Transport. Int J Mol Sci 2018; 19:ijms19113481. [PMID: 30404151 PMCID: PMC6274953 DOI: 10.3390/ijms19113481] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/26/2018] [Accepted: 10/30/2018] [Indexed: 02/06/2023] Open
Abstract
AMP-activated kinase (AMPK) is a serine/threonine kinase that is expressed in most cells and activated by a high cellular AMP/ATP ratio (indicating energy deficiency) or by Ca2+. In general, AMPK turns on energy-generating pathways (e.g., glucose uptake, glycolysis, fatty acid oxidation) and stops energy-consuming processes (e.g., lipogenesis, glycogenesis), thereby helping cells survive low energy states. The functional element of the kidney, the nephron, consists of the glomerulus, where the primary urine is filtered, and the proximal tubule, Henle's loop, the distal tubule, and the collecting duct. In the tubular system of the kidney, the composition of primary urine is modified by the reabsorption and secretion of ions and molecules to yield final excreted urine. The underlying membrane transport processes are mainly energy-consuming (active transport) and in some cases passive. Since active transport accounts for a large part of the cell's ATP demands, it is an important target for AMPK. Here, we review the AMPK-dependent regulation of membrane transport along nephron segments and discuss physiological and pathophysiological implications.
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López-Gambero AJ, Martínez F, Salazar K, Cifuentes M, Nualart F. Brain Glucose-Sensing Mechanism and Energy Homeostasis. Mol Neurobiol 2018; 56:769-796. [PMID: 29796992 DOI: 10.1007/s12035-018-1099-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/25/2018] [Indexed: 01/02/2023]
Abstract
The metabolic and energy state of the organism depends largely on the availability of substrates, such as glucose for ATP production, necessary for maintaining physiological functions. Deregulation in glucose levels leads to the appearance of pathological signs that result in failures in the cardiovascular system and various diseases, such as diabetes, obesity, nephropathy, and neuropathy. Particularly, the brain relies on glucose as fuel for the normal development of neuronal activity. Regions adjacent to the cerebral ventricles, such as the hypothalamus and brainstem, exercise central control in energy homeostasis. These centers house nuclei of neurons whose excitatory activity is sensitive to changes in glucose levels. Determining the different detection mechanisms, the phenotype of neurosecretion, and neural connections involving glucose-sensitive neurons is essential to understanding the response to hypoglycemia through modulation of food intake, thermogenesis, and activation of sympathetic and parasympathetic branches, inducing glucagon and epinephrine secretion and other hypothalamic-pituitary axis-dependent counterregulatory hormones, such as glucocorticoids and growth hormone. The aim of this review focuses on integrating the current understanding of various glucose-sensing mechanisms described in the brain, thereby establishing a relationship between neuroanatomy and control of physiological processes involved in both metabolic and energy balance. This will advance the understanding of increasingly prevalent diseases in the modern world, especially diabetes, and emphasize patterns that regulate and stimulate intake, thermogenesis, and the overall synergistic effect of the neuroendocrine system.
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Affiliation(s)
- A J López-Gambero
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile.,Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, BIONAND, Andalusian Center for Nanomedicine and Biotechnology and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Málaga, Spain
| | - F Martínez
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - K Salazar
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile
| | - M Cifuentes
- Department of Cell Biology, Genetics and Physiology, University of Malaga, IBIMA, BIONAND, Andalusian Center for Nanomedicine and Biotechnology and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Málaga, Spain.
| | - F Nualart
- Laboratory of Neurobiology and Stem Cells NeuroCellT, Department of Cellular Biology, Center for Advanced Microscopy CMA BIO BIO, Faculty of Biological Sciences, University of Concepcion, Concepcion, Chile. .,Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
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Holmes AP, Ray CJ, Coney AM, Kumar P. Is Carotid Body Physiological O 2 Sensitivity Determined by a Unique Mitochondrial Phenotype? Front Physiol 2018; 9:562. [PMID: 29867584 PMCID: PMC5964187 DOI: 10.3389/fphys.2018.00562] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/30/2018] [Indexed: 12/12/2022] Open
Abstract
The mammalian carotid body (CB) is the primary arterial chemoreceptor that responds to acute hypoxia, initiating systemic protective reflex responses that act to maintain O2 delivery to the brain and vital organs. The CB is unique in that it is stimulated at O2 levels above those that begin to impact on the metabolism of most other cell types. Whilst a large proportion of the CB chemotransduction cascade is well defined, the identity of the O2 sensor remains highly controversial. This short review evaluates whether the mitochondria can adequately function as acute O2 sensors in the CB. We consider the similarities between mitochondrial poisons and hypoxic stimuli in their ability to activate the CB chemotransduction cascade and initiate rapid cardiorespiratory reflexes. We evaluate whether the mitochondria are required for the CB to respond to hypoxia. We also discuss if the CB mitochondria are different to those located in other non-O2 sensitive cells, and what might cause them to have an unusually low O2 binding affinity. In particular we look at the potential roles of competitive inhibitors of mitochondrial complex IV such as nitric oxide in establishing mitochondrial and CB O2-sensitivity. Finally, we discuss novel signaling mechanisms proposed to take place within and downstream of mitochondria that link mitochondrial metabolism with cellular depolarization.
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Affiliation(s)
| | | | | | - Prem Kumar
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
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16
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Shen C, Ma W, Zheng W, Huang H, Xia R, Li C, Zhu X. The antioxidant effects of riluzole on the APRE-19 celll model injury-induced by t-BHP. BMC Ophthalmol 2017; 17:210. [PMID: 29169345 PMCID: PMC5701292 DOI: 10.1186/s12886-017-0614-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/16/2017] [Indexed: 11/10/2022] Open
Abstract
Background Age-related macular degeneration (AMD) causes the dysfunction of the retinal pigment epithelial (RPE) cells. In this study, we examined the effects of riluzole, a sustained activator of the TRAAK potassium channel, on human RPE (ARPE-19) cells in an oxidant-induced cell-injury model and elucidate the mechanism of riluzole on RPE cell apoptosis. Methods The follow four groups of ARPE-19 cells were treated with riluzole and/or tert-butyl hydroperoxide (t-BHP) for 24.0 h: control, t-BHP, riluzole, and t-BHP + riluzole. Cell apoptosis was measured by flow cytometry, and Western blotting was performed to analyze the expression of the weakly inward rectifying potassium (TRAAK) channel. Finally, the mitochondrial membrane potential (Δψm) was detected by flow cytometry, and cytochrome C (Cyt-c) release was assessed by Western blotting. Results The viability of the cells in the cotreated group was significantly higher (85.6 ± 3.1%) than that in the t-BHP group (66.2 ± 2.5%). In addition, the cells in the cotreated group had a higher effect on increasing the expression of TRAAK than the t-BHP group. The results also showed that Cyt-c translocation significantly decreased and Δψm increased in the cotreated group. Conclusions These results demonstrate that riluzole protects RPE cells from apoptosis. The protection mechanism of riluzole could be from stabilizing mitochondrial Δψm and preventing the release of Cyt-c. Changes in TRAAK expression might also contribute to the protection of RPE cells.
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Affiliation(s)
- Chaolan Shen
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Wei Ma
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wenbin Zheng
- Frist Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, China
| | - Hao Huang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Renchun Xia
- People's hospital of Deyang city, Deyang, Sichuan, China
| | - Chu Li
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiaobo Zhu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
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Shen KZ, Wu YN, Munhall AC, Johnson SW. AMP kinase regulates ligand-gated K-ATP channels in substantia nigra dopamine neurons. Neuroscience 2016; 330:219-28. [PMID: 27267246 DOI: 10.1016/j.neuroscience.2016.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 12/29/2022]
Abstract
AMP-activated protein kinase (AMPK) is a master enzyme that regulates ATP-sensitive K(+) (K-ATP) channels in pancreatic beta-cells and cardiac myocytes. We used patch pipettes to record currents and potentials to investigate effects of AMPK on K-ATP currents in substantia nigra compacta (SNC) dopamine neurons in slices of rat midbrain. When slices were superfused repeatedly with the K-ATP channel opener diazoxide, we were surprised to find that diazoxide currents gradually increased in magnitude, reaching 300% of the control value 60min after starting whole-cell recording. However, diazoxide current increased significantly more, to 472% of control, when recorded in the presence of the AMPK activator A769662. Moreover, superfusing the slice with the AMPK blocking agent dorsomorphin significantly reduced diazoxide current to 38% of control. Control experiments showed that outward currents evoked by the K-ATP channel opener NN-414 also increased over time, but not currents evoked by the GABAB agonist baclofen. Delaying the application of diazoxide after starting whole-cell recording correlated with augmentation of current. Loose-patch recording showed that diazoxide produced a 34% slowing of spontaneous firing rate that did not intensify with repeated applications of diazoxide. However, superfusion with A769662 significantly augmented the inhibitory effect of diazoxide on firing rate. We conclude that K-ATP channel function is augmented by AMPK, which is activated during the process of making whole-cell recordings. Our results suggest that AMPK and K-ATP interactions may play an important role in regulating dopamine neuronal excitability.
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Affiliation(s)
- Ke-Zhong Shen
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Yan-Na Wu
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Adam C Munhall
- Veterans Affairs Portland Health Care System, Portland, OR 97239, USA
| | - Steven W Johnson
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA; Veterans Affairs Portland Health Care System, Portland, OR 97239, USA.
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Cusanovich DA, Caliskan M, Billstrand C, Michelini K, Chavarria C, De Leon S, Mitrano A, Lewellyn N, Elias JA, Chupp GL, Lang RM, Shah SJ, Decara JM, Gilad Y, Ober C. Integrated analyses of gene expression and genetic association studies in a founder population. Hum Mol Genet 2016; 25:2104-2112. [PMID: 26931462 PMCID: PMC5062579 DOI: 10.1093/hmg/ddw061] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 02/21/2016] [Indexed: 12/17/2022] Open
Abstract
Genome-wide association studies (GWASs) have become a standard tool for dissecting genetic contributions to disease risk. However, these studies typically require extraordinarily large sample sizes to be adequately powered. Strategies that incorporate functional information alongside genetic associations have proved successful in increasing GWAS power. Following this paradigm, we present the results of 20 different genetic association studies for quantitative traits related to complex diseases, conducted in the Hutterites of South Dakota. To boost the power of these association studies, we collected RNA-sequencing data from lymphoblastoid cell lines for 431 Hutterite individuals. We then used Sherlock, a tool that integrates GWAS and expression quantitative trait locus (eQTL) data, to identify weak GWAS signals that are also supported by eQTL data. Using this approach, we found novel associations with quantitative phenotypes related to cardiovascular disease, including carotid intima-media thickness, left atrial volume index, monocyte count and serum YKL-40 levels.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Jack A Elias
- Division of Biology and Medicine, Brown University, Providence, RI 02912, USA and
| | - Geoffrey L Chupp
- Pulmonary and Critical Care, Yale School of Medicine, New Haven, CT 06519, USA
| | - Roberto M Lang
- Department of Medicine, Section of Cardiology, University of Chicago, Chicago, IL 60637, USA
| | - Sanjiv J Shah
- Department of Medicine, Section of Cardiology, University of Chicago, Chicago, IL 60637, USA
| | - Jeanne M Decara
- Department of Medicine, Section of Cardiology, University of Chicago, Chicago, IL 60637, USA
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Buckler KJ, Turner PJ. Functional Properties of Mitochondria in the Type-1 Cell and Their Role in Oxygen Sensing. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 860:69-80. [PMID: 26303469 DOI: 10.1007/978-3-319-18440-1_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The identity of the oxygen sensor in arterial chemoreceptors has been the subject of much speculation. One of the oldest hypotheses is that oxygen is sensed through oxidative phosphorylation. There is a wealth of data demonstrating that arterial chemoreceptors are excited by inhibitors of oxidative phosphorylation. These compounds mimic the effects of hypoxia inhibiting TASK1/3 potassium channels causing membrane depolarisation calcium influx and neurosecretion. The TASK channels of Type-I cells are also sensitive to cytosolic MgATP. The existence of a metabolic signalling pathway in Type-1 cells is thus established; the contentious issue is whether this pathway is also used for acute oxygen sensing. The main criticism is that because cytochrome oxidase has a high affinity for oxygen (P50 ≈ 0.2 mmHg) mitochondrial metabolism should be insensitive to physiological hypoxia. This argument is however predicated on the assumption that chemoreceptor mitochondria are analogous to those of other tissues. We have however obtained new evidence to support the hypothesis that type-1 cell mitochondria are not like those of other cells in that they have an unusually low affinity for oxygen (Mills E, Jobsis FF, J Neurophysiol 35(4):405-428, 1972; Duchen MR, Biscoe TJ, J Physiol 450:13-31, 1992a). Our data confirm that mitochondrial membrane potential, NADH, electron transport and cytochrome oxidase activity in the Type-1 cell are all highly sensitive to hypoxia. These observations not only provide exceptionally strong support for the metabolic hypothesis but also reveal an unknown side of mitochondrial behaviour.
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Affiliation(s)
- Keith J Buckler
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK,
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Rivas-Ramírez P, Cadaveira-Mosquera A, Lamas JA, Reboreda A. Muscarinic modulation of TREK currents in mouse sympathetic superior cervical ganglion neurons. Eur J Neurosci 2015; 42:1797-807. [PMID: 25899939 DOI: 10.1111/ejn.12930] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 03/30/2015] [Accepted: 04/20/2015] [Indexed: 01/05/2023]
Abstract
Muscarinic receptors play a key role in the control of neurotransmission in the autonomic ganglia, which has mainly been ascribed to the regulation of potassium M-currents and voltage-dependent calcium currents. Muscarinic agonists provoke depolarization of the membrane potential and a reduction in spike frequency adaptation in postganglionic neurons, effects that may be explained by M-current inhibition. Here, we report the presence of a riluzole-activated current (IRIL ) that flows through the TREK-2 channels, and that is also inhibited by muscarinic agonists in neurons of the mouse superior cervical ganglion (mSCG). The muscarinic agonist oxotremorine-M (Oxo-M) inhibited the IRIL by 50%, an effect that was abolished by pretreatment with atropine or pirenzepine, but was unaffected in the presence of himbacine. Moreover, these antagonists had similar effects on single-channel TREK-2 currents. IRIL inhibition was unaffected by pretreatment with pertussis toxin. The protein kinase C blocker bisindolylmaleimide did not have an effect, and neither did the inositol triphosphate antagonist 2-aminoethoxydiphenylborane. Nevertheless, the IRIL was markedly attenuated by the phospholipase C (PLC) inhibitor ET-18-OCH3. Finally, the phosphatidylinositol-3-kinase/phosphatidylinositol-4-kinase inhibitor wortmannin strongly attenuated the IRIL , whereas blocking phosphatidylinositol 4,5-bisphosphate (PIP2 ) depletion consistently prevented IRIL inhibition by Oxo-M. These results demonstrate that TREK-2 currents in mSCG neurons are inhibited by muscarinic agonists that activate M1 muscarinic receptors, reducing PIP2 levels via a PLC-dependent pathway. The similarities between the signaling pathways regulating the IRIL and the M-current in the same neurons reflect an important role of this new pathway in the control of autonomic ganglia excitability.
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Affiliation(s)
- P Rivas-Ramírez
- Department of Functional Biology and Health Sciences, Faculty of Biology - CINBIO-IBIV, University of Vigo, Campus Lagoas-Marcosende, 36310, Vigo, Spain
| | - A Cadaveira-Mosquera
- Department of Functional Biology and Health Sciences, Faculty of Biology - CINBIO-IBIV, University of Vigo, Campus Lagoas-Marcosende, 36310, Vigo, Spain
| | - J A Lamas
- Department of Functional Biology and Health Sciences, Faculty of Biology - CINBIO-IBIV, University of Vigo, Campus Lagoas-Marcosende, 36310, Vigo, Spain
| | - A Reboreda
- Department of Functional Biology and Health Sciences, Faculty of Biology - CINBIO-IBIV, University of Vigo, Campus Lagoas-Marcosende, 36310, Vigo, Spain
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Dadi PK, Luo B, Vierra NC, Jacobson DA. TASK-1 Potassium Channels Limit Pancreatic α-Cell Calcium Influx and Glucagon Secretion. MOLECULAR ENDOCRINOLOGY (BALTIMORE, MD.) 2015. [PMID: 25849724 DOI: 10.1210/me.2014‐1321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glucose regulation of pancreatic α-cell Ca(2+) entry through voltage-dependent Ca(2+) channels is essential for normal glucagon secretion and becomes defective during the pathogenesis of diabetes mellitus. The 2-pore domain K(+) channel, TWIK-related acid-sensitive K(+) channel 1 (TASK-1), is an important modulator of membrane voltage and Ca(2+) entry. However, its role in α-cells has not been determined. Therefore, we addressed how TASK-1 channels regulate α-cell electrical activity, Ca(2+) entry, and glucagon secretion. We find that TASK-1 channels expressed in human and rodent α-cells are blocked by the TASK-1 channel inhibitor A1899. Alpha-cell 2-pore domain K(+) currents were also significantly reduced after ablation of mouse α-cell TASK-1 channels. Inhibition of TASK-1 channels with A1899 caused plasma membrane potential depolarization in both human and mouse α-cells, which resulted in increased electrical excitability. Moreover, ablation of α-cell TASK-1 channels increased α-cell electrical excitability under elevated glucose (11 mM) conditions compared with control α-cells. This resulted in significantly elevated α-cell Ca(2+) influx when TASK-1 channels were inhibited in the presence of high glucose (14 mM). However, there was an insignificant change in α-cell Ca(2+) influx after TASK-1 inhibition in low glucose (1 mM). Glucagon secretion from mouse and human islets was also elevated specifically in high (11 mM) glucose after acute TASK-1 inhibition. Interestingly, mice deficient for α-cell TASK-1 showed improvements in both glucose inhibition of glucagon secretion and glucose tolerance, which resulted from the chronic loss of α-cell TASK-1 currents. Therefore, these data suggest an important role for TASK-1 channels in limiting α-cell excitability and glucagon secretion during glucose stimulation.
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Affiliation(s)
- Prasanna K Dadi
- Department of Molecular Physiology and Biophysics (P.K.D., N.C.V., D.A.J.), Vanderbilt University, Nashville, Tennessee 37232-0615; and University of Oklahoma College of Medicine (B.L.), Oklahoma City, Oklahoma 73104-5042
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Dadi PK, Luo B, Vierra NC, Jacobson DA. TASK-1 Potassium Channels Limit Pancreatic α-Cell Calcium Influx and Glucagon Secretion. Mol Endocrinol 2015; 29:777-87. [PMID: 25849724 DOI: 10.1210/me.2014-1321] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Glucose regulation of pancreatic α-cell Ca(2+) entry through voltage-dependent Ca(2+) channels is essential for normal glucagon secretion and becomes defective during the pathogenesis of diabetes mellitus. The 2-pore domain K(+) channel, TWIK-related acid-sensitive K(+) channel 1 (TASK-1), is an important modulator of membrane voltage and Ca(2+) entry. However, its role in α-cells has not been determined. Therefore, we addressed how TASK-1 channels regulate α-cell electrical activity, Ca(2+) entry, and glucagon secretion. We find that TASK-1 channels expressed in human and rodent α-cells are blocked by the TASK-1 channel inhibitor A1899. Alpha-cell 2-pore domain K(+) currents were also significantly reduced after ablation of mouse α-cell TASK-1 channels. Inhibition of TASK-1 channels with A1899 caused plasma membrane potential depolarization in both human and mouse α-cells, which resulted in increased electrical excitability. Moreover, ablation of α-cell TASK-1 channels increased α-cell electrical excitability under elevated glucose (11 mM) conditions compared with control α-cells. This resulted in significantly elevated α-cell Ca(2+) influx when TASK-1 channels were inhibited in the presence of high glucose (14 mM). However, there was an insignificant change in α-cell Ca(2+) influx after TASK-1 inhibition in low glucose (1 mM). Glucagon secretion from mouse and human islets was also elevated specifically in high (11 mM) glucose after acute TASK-1 inhibition. Interestingly, mice deficient for α-cell TASK-1 showed improvements in both glucose inhibition of glucagon secretion and glucose tolerance, which resulted from the chronic loss of α-cell TASK-1 currents. Therefore, these data suggest an important role for TASK-1 channels in limiting α-cell excitability and glucagon secretion during glucose stimulation.
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Affiliation(s)
- Prasanna K Dadi
- Department of Molecular Physiology and Biophysics (P.K.D., N.C.V., D.A.J.), Vanderbilt University, Nashville, Tennessee 37232-0615; and University of Oklahoma College of Medicine (B.L.), Oklahoma City, Oklahoma 73104-5042
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TASK channels in arterial chemoreceptors and their role in oxygen and acid sensing. Pflugers Arch 2015; 467:1013-25. [PMID: 25623783 PMCID: PMC4428840 DOI: 10.1007/s00424-015-1689-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/06/2015] [Accepted: 01/07/2015] [Indexed: 01/05/2023]
Abstract
Arterial chemoreceptors play a vital role in cardiorespiratory control by providing the brain with information regarding blood oxygen, carbon dioxide, and pH. The main chemoreceptor, the carotid body, is composed of sensory (type 1) cells which respond to hypoxia or acidosis with a depolarising receptor potential which in turn activates voltage-gated calcium entry, neurosecretion and excitation of adjacent afferent nerves. The receptor potential is generated by inhibition of Twik-related acid-sensitive K(+) channel 1 and 3 (TASK1/TASK3) heterodimeric channels which normally maintain the cells' resting membrane potential. These channels are thought to be directly inhibited by acidosis. Oxygen sensitivity, however, probably derives from a metabolic signalling pathway. The carotid body, isolated type 1 cells, and all forms of TASK channel found in the type 1 cell, are highly sensitive to inhibitors of mitochondrial metabolism. Moreover, type1 cell TASK channels are activated by millimolar levels of MgATP. In addition to their role in the transduction of chemostimuli, type 1 cell TASK channels have also been implicated in the modulation of chemoreceptor function by a number of neurocrine/paracrine signalling molecules including adenosine, GABA, and serotonin. They may also be instrumental in mediating the depression of the acute hypoxic ventilatory response that occurs with some general anaesthetics. Modulation of TASK channel activity is therefore a key mechanism by which the excitability of chemoreceptors can be controlled. This is not only of physiological importance but may also offer a therapeutic strategy for the treatment of cardiorespiratory disorders that are associated with chemoreceptor dysfunction.
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Activation of neurotensin receptor 1 facilitates neuronal excitability and spatial learning and memory in the entorhinal cortex: beneficial actions in an Alzheimer's disease model. J Neurosci 2014; 34:7027-42. [PMID: 24828655 DOI: 10.1523/jneurosci.0408-14.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurotensin (NT) is a tridecapeptide distributed in the CNS, including the entorhinal cortex (EC), a structure that is crucial for learning and memory and undergoes the earliest pathological alterations in Alzheimer's disease (AD). Whereas NT has been implicated in modulating cognition, the cellular and molecular mechanisms by which NT modifies cognitive processes and the potential therapeutic roles of NT in AD have not been determined. Here we examined the effects of NT on neuronal excitability and spatial learning in the EC, which expresses high density of NT receptors. Brief application of NT induced persistent increases in action potential firing frequency, which could last for at least 1 h. NT-induced facilitation of neuronal excitability was mediated by downregulation of TREK-2 K(+) channels and required the functions of NTS1, phospholipase C, and protein kinase C. Microinjection of NT or NTS1 agonist, PD149163, into the EC increased spatial learning as assessed by the Barnes Maze Test. Activation of NTS1 receptors also induced persistent increases in action potential firing frequency and significantly improved the memory status in APP/PS1 mice, an animal model of AD. Our study identifies a cellular substrate underlying learning and memory and suggests that NTS1 agonists may exert beneficial actions in an animal model of AD.
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AMP kinase regulates K-ATP currents evoked by NMDA receptor stimulation in rat subthalamic nucleus neurons. Neuroscience 2014; 274:138-52. [PMID: 24875176 DOI: 10.1016/j.neuroscience.2014.05.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/10/2014] [Accepted: 05/18/2014] [Indexed: 11/21/2022]
Abstract
Our lab recently showed that N-methyl-D-aspartate (NMDA) evokes ATP-sensitive K(+) (K-ATP) currents in subthalamic nucleus (STN) neurons in slices of the rat brain. Both K-ATP channels and 5'-adenosine monophosphate-activated protein kinase (AMPK) are considered cellular energy sensors because their activities are influenced by the phosphorylation state of adenosine nucleotides. Moreover, AMPK has been shown to regulate K-ATP function in a variety of tissues including pancreas, cardiac myocytes, and hypothalamus. We used whole-cell patch clamp recordings to study the effect of AMPK activation on K-ATP channel function in STN neurons in slices of the rat brain. We found that bath or intracellular application of the AMPK activators A769662 and PT1 augmented tolbutamide-sensitive K-ATP currents evoked by NMDA receptor stimulation. The effect of AMPK activators was blocked by the AMPK inhibitor dorsomorphin (compound C), and by STO609, an inhibitor of the upstream AMPK activator CaMKKβ. AMPK augmentation of NMDA-induced K-ATP current was also blocked by intracellular BAPTA and by inhibitors of nitric oxide synthase and guanylyl cyclase. However, A769662 did not augment currents evoked by the K-ATP channel opener diazoxide. In the presence of NMDA, A769662 inhibited depolarizing plateau potentials and burst firing, both of which could be antagonized by tolbutamide or dorsomorphin. These studies show that AMPK augments NMDA-induced K-ATP currents by a Ca(2+)-dependent process that involves nitric oxide and cGMP. By augmenting K-ATP currents, AMPK activation would be expected to dampen the excitatory effect of glutamate-mediated transmission in the STN.
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Enyedi P, Veres I, Braun G, Czirják G. Tubulin binds to the cytoplasmic loop of TRESK background K⁺ channel in vitro. PLoS One 2014; 9:e97854. [PMID: 24830385 PMCID: PMC4022642 DOI: 10.1371/journal.pone.0097854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/25/2014] [Indexed: 12/02/2022] Open
Abstract
The cytoplasmic loop between the second and third transmembrane segments is pivotal in the regulation of TRESK (TWIK-related spinal cord K+ channel, K2P18.1, KCNK18). Calcineurin binds to this region and activates the channel by dephosphorylation in response to the calcium signal. Phosphorylation-dependent anchorage of 14-3-3 adaptor protein also modulates TRESK at this location. In the present study, we identified molecular interacting partners of the intracellular loop. By an affinity chromatography approach using the cytoplasmic loop as bait, we have verified the specific association of calcineurin and 14-3-3 to the channel. In addition to these known interacting proteins, we observed substantial binding of tubulin to the intracellular loop. Successive truncation of the polypeptide and pull-down experiments from mouse brain cytosol narrowed down the region sufficient for the binding of tubulin to a 16 amino acid sequence: LVLGRLSYSIISNLDE. The first six residues of this sequence are similar to the previously reported tubulin-binding region of P2X2 purinergic receptor. The tubulin-binding site of TRESK is located close to the protein kinase A (PKA)-dependent 14-3-3-docking motif of the channel. We provide experimental evidence suggesting that 14-3-3 competes with tubulin for the binding to the cytoplasmic loop of TRESK. It is intriguing that the 16 amino acid tubulin-binding sequence includes the serines, which were previously shown to be phosphorylated by microtubule-affinity regulating kinases (MARK kinases) and contribute to channel inhibition. Although tubulin binds to TRESK in vitro, it remains to be established whether the two proteins also interact in the living cell.
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Affiliation(s)
- Péter Enyedi
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Irén Veres
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Gabriella Braun
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Gábor Czirják
- Department of Physiology, Semmelweis University, Budapest, Hungary
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27
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Kim D, Kang D, Martin EA, Kim I, Carroll JL. Effects of modulators of AMP-activated protein kinase on TASK-1/3 and intracellular Ca(2+) concentration in rat carotid body glomus cells. Respir Physiol Neurobiol 2014; 195:19-26. [PMID: 24530802 DOI: 10.1016/j.resp.2014.01.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 01/29/2014] [Accepted: 01/30/2014] [Indexed: 01/11/2023]
Abstract
Acute hypoxia depolarizes carotid body chemoreceptor (glomus) cells and elevates intracellular Ca(2+) concentration ([Ca(2+)]i). Recent studies suggest that AMP-activated protein kinase (AMPK) mediates these effects of hypoxia by inhibiting the background K(+) channels such as TASK. Here we studied the effects of modulators of AMPK on TASK activity in cell-attached patches. Activators of AMPK (1mM AICAR and 0.1-0.5mM A769662) did not inhibit TASK activity or cause depolarization during acute (10min) or prolonged (2-3h) exposure. Hypoxia inhibited TASK activity by ∼70% in cells pretreated with AICAR or A769662. Both AICAR and A769662 (15-40min) failed to increase [Ca(2+)]i in glomus cells. Compound C (40μM), an inhibitor of AMPK, showed no effect on hypoxia-induced inhibition of TASK. AICAR and A769662 phosphorylated AMPKα in PC12 cells, and Compound C blocked the phosphorylation. Our results suggest that AMPK does not affect TASK activity and is not involved in hypoxia-induced elevation of intracellular [Ca(2+)] in isolated rat carotid body glomus cells.
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Affiliation(s)
- Donghee Kim
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States.
| | - Dawon Kang
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States; Department of Physiology and Institute of Health Sciences, Gyeongsang National University School of Medicine, 90 Chilam, Jinju 660-751, Republic of Korea
| | - Elizabeth A Martin
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, United States
| | - Insook Kim
- Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, 1 Children's Way, Little Rock, AR 72202, United States
| | - John L Carroll
- Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, 1 Children's Way, Little Rock, AR 72202, United States.
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Dërmaku-Sopjani M, Abazi S, Faggio C, Kolgeci J, Sopjani M. AMPK-sensitive cellular transport. J Biochem 2014; 155:147-58. [PMID: 24440827 DOI: 10.1093/jb/mvu002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The energy sensing AMP-activated protein kinase (AMPK) regulates cellular and whole-body energy balance through stimulating catabolic ATP-generating and suppressing anabolic ATP-consuming pathways thereby helping cells survive during energy depletion. The kinase has previously been reported to be either directly or indirectly involved in the regulation of several carriers, channels and pumps of high significance in cellular physiology. Thus AMPK provides a necessary link between cellular energy metabolism and cellular transport activity. Better understanding of the AMPK role in cellular transport offers a potential for improved therapies in various human diseases and disorders. In this review, we discuss recent advances in understanding the role and function of AMPK in transport regulation under physiological and pathological states.
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Affiliation(s)
- Miribane Dërmaku-Sopjani
- Faculty of Medicine, University of Prishtina, Str. Bulevardi i Dëshmorëve, p.n. 10 000 Prishtina, Kosova; Department of Chemistry, University of Prishtina, Str. 'Nëna Terezë' p.n. 10 000 Prishtina, Kosova; Department of Chemistry, University of Tirana, Tirana, Albania; and Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31, 98166 S.Agata-Messina, Italy
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29
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Lang F, Föller M. Regulation of ion channels and transporters by AMP-activated kinase (AMPK). Channels (Austin) 2013; 8:20-8. [PMID: 24366036 DOI: 10.4161/chan.27423] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The energy-sensing AMP-activated kinase AMPK ensures survival of energy-depleted cells by stimulating ATP production and limiting ATP utilization. Both energy production and energy consumption are profoundly influenced by transport processes across the cell membane including channels, carriers and pumps. Accordingly, AMPK is a powerful regulator of transport across the cell membrane. AMPK regulates diverse K(+) channels, Na(+) channels, Ca(2+) release activated Ca(2+) channels, Cl(-) channels, gap junctional channels, glucose carriers, Na(+)/H(+)-exchanger, monocarboxylate-, phosphate-, creatine-, amino acid-, peptide- and osmolyte-transporters, Na(+)/Ca(2+)-exchanger, H(+)-ATPase and Na(+)/K(+)-ATPase. AMPK activates ubiquitin ligase Nedd4-2, which labels several plasma membrane proteins for degradation. AMPK further regulates transport proteins by inhibition of Rab GTPase activating protein (GAP) TBC1D1. It stimulates phosphatidylinositol 3-phosphate 5-kinase PIKfyve and inhibits phosphatase and tensin homolog (PTEN) via glycogen synthase kinase 3β (GSK3β). Moreover, it stabilizes F-actin as well as downregulates transcription factor NF-κB. All those cellular effects serve to regulate transport proteins.
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Affiliation(s)
- Florian Lang
- Department of Physiology; University of Tübingen; Tübingen, Germany
| | - Michael Föller
- Department of Physiology; University of Tübingen; Tübingen, Germany
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30
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Bhavsar SK, Hosseinzadeh Z, Brenner D, Honisch S, Jilani K, Liu G, Szteyn K, Sopjani M, Mak TW, Shumilina E, Lang F. Energy-sensitive regulation of Na+/K+-ATPase by Janus kinase 2. Am J Physiol Cell Physiol 2013; 306:C374-84. [PMID: 24304834 DOI: 10.1152/ajpcell.00320.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Janus kinase 2 (JAK2) contributes to intracellular signaling of leptin and erythropoietin, hormones protecting cells during energy depletion. The present study explores whether JAK2 is activated by energy depletion and regulates Na(+)/K(+)-ATPase, the major energy-consuming pump. In Jurkat cells, JAK2 activity was determined by radioactive kinase assay, phosphorylated JAK2 detected by Western blotting, ATP levels measured by luciferase assay, as well as Na(+)/K(+)-ATPase α1-subunit transcript and protein abundance determined by real-time PCR and Western blotting, respectively. Ouabain-sensitive K(+)-induced currents (Ipump) were measured by whole cell patch clamp. Ipump was further determined by dual-electrode voltage clamp in Xenopus oocytes injected with cRNA-encoding JAK2, active (V617F)JAK2, or inactive (K882E)JAK2. As a result, in Jurkat T cells, JAK2 activity significantly increased following energy depletion by sodium azide (NaN3) or 2,4- dinitro phenol (DNP). DNP- and NaN3-induced decrease of cellular ATP was significantly augmented by JAK2 inhibitor AG490 and blunted by Na(+)/K(+)-ATPase inhibitor ouabain. DNP decreased and AG490 enhanced Ipump as well as Na(+)/K(+)-ATPase α1-subunit transcript and protein abundance. The α1-subunit transcript levels were also enhanced by signal transducer and activator of transcription-5 inhibitor CAS 285986-31-4. In Xenopus oocytes, Ipump was significantly decreased by expression of JAK2 and (V617F)JAK2 but not of (K882E)JAK2, effects again reversed by AG490. In (V617F)JAK2-expressing Xenopus oocytes, neither DNP nor NaN3 resulted in further decline of Ipump. In Xenopus oocytes, the effect of (V617F)JAK2 on Ipump was not prevented by inhibition of transcription with actinomycin. In conclusion, JAK2 is a novel energy-sensing kinase that curtails energy consumption by downregulating Na(+)/K(+)-ATPase expression and activity.
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31
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GE RUILIANG, HU LEI, TAI YILIN, XUE FENG, YUAN LEI, WEI GONGTIAN, WANG YI. Flufenamic acid promotes angiogenesis through AMPK activation. Int J Oncol 2013; 42:1945-50. [DOI: 10.3892/ijo.2013.1891] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 02/21/2013] [Indexed: 11/06/2022] Open
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Abstract
Ion transport processes are highly energy consuming. It is therefore critical to couple ion transport processes to the metabolic state of the cell. An important player in this coupling appears to be the AMP-activated protein kinase (AMPK). This kinase becomes activated during conditions of cellular metabolic stress and is well-known for its role in promoting ATP-generating catabolic pathways while turning off ATP-utilizing anabolic pathways. Over the past decade AMPK has also emerged as a key regulator of ion channel activity as an increasing number of ion channels are reported to be either directly or indirectly regulated by the kinase. AMPK therefore provides a necessary link between cellular energy levels and ion channel activity.
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Affiliation(s)
- Martin N Andersen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia; Department of Biomedical Sciences; The Faculty of Health Sciences; University of Copenhagen; Copenhagen, Denmark
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33
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Giordanetto F, Karis D. Direct AMP-activated protein kinase activators: a review of evidence from the patent literature. Expert Opin Ther Pat 2012; 22:1467-77. [DOI: 10.1517/13543776.2012.743994] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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34
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Lang F, Eylenstein A, Shumilina E. Regulation of Orai1/STIM1 by the kinases SGK1 and AMPK. Cell Calcium 2012; 52:347-54. [PMID: 22682960 DOI: 10.1016/j.ceca.2012.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 01/08/2023]
Abstract
STIM and Orai isoforms orchestrate store operated Ca2+ entry (SOCE) and thus cytosolic Ca2+ fluctuations following stimulation by hormones, growth factors and further mediators. Orai1 is a target of Nedd4-2, an ubiquitin ligase preparing several plasma membrane proteins for degradation. Phosphorylation of Nedd4-2 by the serum and glucocorticoid inducible kinase SGK1 leads to the binding of Nedd4-2 to the protein 14-3-3 thus preventing its interaction with Orai1. Nedd4-2 is activated by the energy sensing AMP activated kinase AMPK. Thus, SGK1 disrupts and AMPK fosters degradation of Orai1. New synthesis of both, Orai1 and STIM1, is stimulated by the transcription factor NF-κB (nuclear factor kappa B), which binds to the respective promoter regions of the genes encoding STIM1 and Orai1. SGK1 upregulates and AMPK presumably downregulates NF-κB and thus de novo synthesis of Orai1 and STIM1 proteins. The regulation by SGK1 links SOCE to the signaling of a wide variety of hormones and growth factors, the AMPK dependent regulation of Orai1 and STIM1 may serve to limit inadequate activation of SOCE following energy depletion, which is otherwise expected to activate SOCE by depletion of intracellular Ca2+ stores due to impairment of the ATP consuming sarco/endoplasmatic reticulum Ca2+ ATPase SERCA.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
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Mkrtchian S, Kåhlin J, Ebberyd A, Gonzalez C, Sanchez D, Balbir A, Kostuk EW, Shirahata M, Fagerlund MJ, Eriksson LI. The human carotid body transcriptome with focus on oxygen sensing and inflammation--a comparative analysis. J Physiol 2012; 590:3807-19. [PMID: 22615433 DOI: 10.1113/jphysiol.2012.231084] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The carotid body (CB) is the key oxygen sensing organ. While the expression of CB specific genes is relatively well studied in animals, corresponding data for the human CB are missing. In this study we used five surgically removed human CBs to characterize the CB transcriptome with microarray and PCR analyses, and compared the results with mice data. In silico approaches demonstrated a unique gene expression profile of the human and mouse CB transcriptomes and an unexpected upregulation of both human and mouse CB genes involved in the inflammatory response compared to brain and adrenal gland data. Human CBs express most of the genes previously proposed to be involved in oxygen sensing and signalling based on animal studies, including NOX2, AMPK, CSE and oxygen sensitive K+ channels. In the TASK subfamily of K+ channels, TASK-1 is expressed in human CBs, while TASK-3 and TASK-5 are absent, although we demonstrated both TASK-1 and TASK-3 in one of the mouse reference strains. Maxi-K was expressed exclusively as the spliced variant ZERO in the human CB. In summary, the human CB transcriptome shares important features with the mouse CB, but also differs significantly in the expression of a number of CB chemosensory genes. This study provides key information for future functional investigations on the human carotid body.
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Affiliation(s)
- Souren Mkrtchian
- Section for Anesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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Nurbaeva MK, Schmid E, Szteyn K, Yang W, Viollet B, Shumilina E, Lang F. Enhanced Ca²⁺ entry and Na+/Ca²⁺ exchanger activity in dendritic cells from AMP-activated protein kinase-deficient mice. FASEB J 2012; 26:3049-58. [PMID: 22474243 DOI: 10.1096/fj.12-204024] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In dendritic cells (DCs), chemotactic chemokines, such as CXCL12, rapidly increase cytosolic Ca(2+)concentrations ([Ca(2+)](i)) by triggering Ca(2+) release from intracellular stores followed by store-operated Ca(2+) (SOC) entry. Increase of [Ca(2+)](i) is blunted and terminated by Ca(2+) extrusion, accomplished by K(+)-independent Na(+)/Ca(2+) exchangers (NCXs) and K(+)-dependent Na(+)/Ca(2+) exchangers (NCKXs). Increased [Ca(2+)](i) activates energy-sensing AMP-activated protein kinase (AMPK), which suppresses proinflammatory responses of DCs and macrophages. The present study explored whether AMPK participates in the regulation of DC [Ca(2+)](i) and migration. DCs were isolated from AMPKα1-deficient (ampk(-/-)) mice and, as control, from their wild-type (ampk(+/+)) littermates. AMPKα1, Orai1-2, STIM1-2, and mitochondrial calcium uniporter protein expression was determined by Western blotting, [Ca(2+)](i) by Fura-2 fluorescence, SOC entry by inhibition of endosomal Ca(2+) ATPase with thapsigargin (1 μM), Na(+)/Ca(2+) exchanger activity from increase of [Ca(2+)](i), and respective whole-cell current in patch clamp following removal of extracellular Na(+). Migration was quantified utilizing transwell chambers. AMPKα1 protein is expressed in ampk(+/+) DCs but not in ampk(-/-) DCs. CXCL12 (300 ng/ml)-induced increase of [Ca(2+)](i), SOC entry, Orai 1 protein abundance, NCX, and NCKX were all significantly higher in ampk(-/-) DCs than in ampk(+/+) DCs. NCX and NCKX currents were similarly increased in ampk(-/-) DCs. Moreover, CXCL12 (50 ng/ml)-induced DC migration was enhanced in ampk(-/-) DCs. AMPK thus inhibits SOC entry, Na(+)/Ca(2+) exchangers, and migration of DCs.
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Effects of exogenous hydrogen sulphide on calcium signalling, background (TASK) K channel activity and mitochondrial function in chemoreceptor cells. Pflugers Arch 2012; 463:743-54. [PMID: 22419174 PMCID: PMC3323823 DOI: 10.1007/s00424-012-1089-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 02/17/2012] [Indexed: 12/24/2022]
Abstract
It has been proposed that endogenous H2S mediates oxygen sensing in chemoreceptors; this study investigates the mechanisms by which H2S excites carotid body type 1 cells. H2S caused a rapid reversible increase in intracellular calcium with EC50 ≈ 6 μM. This [Ca2+]i response was abolished in Ca-free Tyrode. In perforated patch current clamp recordings, H2S depolarised type 1 cells from −59 to −35 mV; this was accompanied by a robust increase in [Ca2+]i. Voltage clamping at the resting membrane potential abolished the H2S-induced rise in [Ca2+]i. H2S inhibited background K+ current in whole cell perforated patch and reduced background K+ channel activity in cell-attached patch recordings. It is concluded that H2S excites type 1 cells through the inhibition of background (TASK) potassium channels leading to membrane depolarisation and voltage-gated Ca2+ entry. These effects mimic those of hypoxia. H2S also inhibited mitochondrial function over a similar concentration range as assessed by NADH autofluorescence and measurement of intracellular magnesium (an index of decline in MgATP). Cyanide inhibited background K channels to a similar extent to H2S and prevented H2S exerting any further influence over channel activity. These data indicate that the effects of H2S on background K channels are a consequence of inhibition of oxidative phosphorylation. Whilst this does not preclude a role for endogenous H2S in oxygen sensing via the inhibition of cytochrome oxidase, the levels of H2S required raise questions as to the viability of such a mechanism.
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Rodriguez EC, Robertson RM. Protective effect of hypothermia on brain potassium homeostasis during repetitive anoxia in Drosophila melanogaster. J Exp Biol 2012; 215:4157-65. [DOI: 10.1242/jeb.074468] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Summary
Oxygen deprivation in nervous tissue depolarizes cell membranes, increasing extracellular potassium concentration ([K+]o). Thus, [K+]o can be used to assess neural failure. The effect of temperature (17°C, 23°C or 29°C) on the maintenance of brain [K+]o homeostasis in male Drosophila melanogaster (w1118) individuals was assessed during repeated anoxic comas induced by N2 gas. Brain [K+]o was continuously monitored using K+-sensitive microelectrodes while body temperature was changed using a thermo electric cooler (TEC). Repetitive anoxia resulted in a loss of the ability to maintain [K+]o baseline at 6.6±0.3 mM. The total [K+]o baseline variation (Δ[K+]o) was stabilized at 17°C (-1.1±1.3 mM), mildly rose at 23°C (17.3±1.4 mM), and considerably increased at 29°C (332.7±83.0 mM). We conclude that 1) reperfusion patterns consisting of long anoxia, short normoxia and high cycle frequency increased disruption of brain [K+]o baseline maintenance, and 2) hypothermia had a protective effect on brain K+ homeostasis during repetitive anoxia. Male flies are suggested as a useful model for examining deleterious consequences of O2 reperfusion with possible application on therapeutical treatment of stroke or heart attack.
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Abstract
The discovery of the sensory nature of the carotid body dates back to the beginning of the 20th century. Following these seminal discoveries, research into carotid body mechanisms moved forward progressively through the 20th century, with many descriptions of the ultrastructure of the organ and stimulus-response measurements at the level of the whole organ. The later part of 20th century witnessed the first descriptions of the cellular responses and electrophysiology of isolated and cultured type I and type II cells, and there now exist a number of testable hypotheses of chemotransduction. The goal of this article is to provide a comprehensive review of current concepts on sensory transduction and transmission of the hypoxic stimulus at the carotid body with an emphasis on integrating cellular mechanisms with the whole organ responses and highlighting the gaps or discrepancies in our knowledge. It is increasingly evident that in addition to hypoxia, the carotid body responds to a wide variety of blood-borne stimuli, including reduced glucose and immune-related cytokines and we therefore also consider the evidence for a polymodal function of the carotid body and its implications. It is clear that the sensory function of the carotid body exhibits considerable plasticity in response to the chronic perturbations in environmental O2 that is associated with many physiological and pathological conditions. The mechanisms and consequences of carotid body plasticity in health and disease are discussed in the final sections of this article.
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Affiliation(s)
- Prem Kumar
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom.
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Mirkovic K, Wickman K. Identification and characterization of alternative splice variants of the mouse Trek2/Kcnk10 gene. Neuroscience 2011; 194:11-8. [PMID: 21821104 DOI: 10.1016/j.neuroscience.2011.07.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/29/2011] [Accepted: 07/25/2011] [Indexed: 10/17/2022]
Abstract
Two-pore domain K(+) (K(2P)) channels underlie leak or background potassium conductances in many cells. The Trek subfamily of K(2P) channels, which includes Trek1/Kcnk2 and Trek2/Kcnk10 and has been implicated in depression, nociception, and cognition, exhibits complex regulation and can modulate cell excitability in response to a wide array of stimuli. While alternative translation initiation and alternative splicing contribute to the structural and functional diversity of Trek1, the impact of post-transcriptional modifications on the expression and function of Trek2 is unclear. Here, we characterized two novel splice isoforms of the mouse Trek2 gene. One variant is a truncated form of Trek2 that possesses two transmembrane segments and one pore domain (Trek2-1p), while the other (Trek2b) differs from two known mouse Trek2 isoforms (Trek2a and Trek2c) at the extreme amino terminus. Both Trek2-1p and Trek2b, and Trek2a and Trek2c, showed prominent expression in the mouse CNS. Expression patterns of the Trek2 variants within the CNS were largely overlapping, though some isoform-specific differences were noted. Heterologous expression of Trek2-1p yielded no novel whole-cell currents in transfected human embryonic kidney (HEK) 293 cells. In contrast, expression of Trek2b correlated with robust K(+) currents that were ~fivefold larger than currents measured in cells expressing Trek2a or Trek2c, a difference mirrored by significantly higher levels of Trek2b found at the plasma membrane. This study provides new insights into the molecular diversity of Trek channels and suggests a potential role for the Trek2 amino terminus in channel trafficking and/or stability.
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Affiliation(s)
- K Mirkovic
- Department of Pharmacology, University of Minnesota, 321 Church Street SE, Minneapolis, MN 55455, USA
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Chi Y, Li K, Yan Q, Koizumi S, Shi L, Takahashi S, Zhu Y, Matsue H, Takeda M, Kitamura M, Yao J. Nonsteroidal Anti-Inflammatory Drug Flufenamic Acid Is a Potent Activator of AMP-Activated Protein Kinase. J Pharmacol Exp Ther 2011; 339:257-66. [DOI: 10.1124/jpet.111.183020] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Koos BJ. Adenosine A₂a receptors and O₂ sensing in development. Am J Physiol Regul Integr Comp Physiol 2011; 301:R601-22. [PMID: 21677265 DOI: 10.1152/ajpregu.00664.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Reduced mitochondrial oxidative phosphorylation, via activation of adenylate kinase and the resulting exponential rise in the cellular AMP/ATP ratio, appears to be a critical factor underlying O₂ sensing in many chemoreceptive tissues in mammals. The elevated AMP/ATP ratio, in turn, activates key enzymes that are involved in physiologic adjustments that tend to balance ATP supply and demand. An example is the conversion of AMP to adenosine via 5'-nucleotidase and the resulting activation of adenosine A(₂A) receptors, which are involved in acute oxygen sensing by both carotid bodies and the brain. In fetal sheep, A(₂A) receptors associated with carotid bodies trigger hypoxic cardiovascular chemoreflexes, while central A(₂A) receptors mediate hypoxic inhibition of breathing and rapid eye movements. A(₂A) receptors are also involved in hypoxic regulation of fetal endocrine systems, metabolism, and vascular tone. In developing lambs, A(₂A) receptors play virtually no role in O₂ sensing by the carotid bodies, but brain A(₂A) receptors remain critically involved in the roll-off ventilatory response to hypoxia. In adult mammals, A(₂A) receptors have been implicated in O₂ sensing by carotid glomus cells, while central A(₂A) receptors likely blunt hypoxic hyperventilation. In conclusion, A(₂A) receptors are crucially involved in the transduction mechanisms of O₂ sensing in fetal carotid bodies and brains. Postnatally, central A(₂A) receptors remain key mediators of hypoxic respiratory depression, but they are less critical for O₂ sensing in carotid chemoreceptors, particularly in developing lambs.
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Affiliation(s)
- Brian J Koos
- Department of Obstetrics and Gynecology; Brain Research Institute, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.
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43
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Abstract
Neural circuits are especially vulnerable to metabolic stress. The locust (Locusta migratoria) responds to anoxia by entering a coma during which neural and muscular systems shut down. During anoxic coma, arrest of the ventilatory central pattern generator is tightly correlated with an abrupt spreading depression (SD)-like increase in extracellular potassium concentration within the metathoracic neuropile. We examined the role of the AMP-activated protein kinase (AMPK), an evolutionarily conserved sensor of cellular energy status, in anoxia-induced ventilatory arrest and SD-like events in the locust. Perfusion of sodium azide (NaN(3); mitochondrial toxin) induced SD, temporary coma, and profound changes in the ventilatory motor pattern characterized as a rapid rhythm before coma and a slower rhythm following recovery. AMPK activation using 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) mimicked the motor pattern changes induced by NaN(3) but did not induce SD and coma. The effects of NaN(3) on the ventilatory rhythm were reversed by perfusion of compound-C (AMPK inhibitor) or glucose, and the effects of AICAR were also reversed by compound-C, confirming the modulatory roles of AMPK and energy status. Ouabain-induced recurring SD was suppressed by inhibition of AMPK and exacerbated by its activation. We show that the motor pattern changes induced by metabolic stress are not the result of SD alone, but that AMPK is necessary and sufficient for these changes and that AMPK activity strongly influences susceptibility to SD.
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Peers C, Wyatt CN, Evans AM. Mechanisms for acute oxygen sensing in the carotid body. Respir Physiol Neurobiol 2010; 174:292-8. [PMID: 20736087 DOI: 10.1016/j.resp.2010.08.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/16/2010] [Accepted: 08/17/2010] [Indexed: 12/22/2022]
Abstract
Hypoxic chemotransduction in the carotid body requires release of excitatory transmitters from type I cells that activate afferent sensory neurones. Transmitter release is dependent on voltage-gated Ca2+ entry which is evoked by membrane depolarization. This excitatory response to hypoxia is initiated by inhibition of specific O2 sensitive K+ channels, of which several types have been reported. Here, we discuss mechanisms which have been put forward to account for hypoxic inhibition of type I cell K+ channels. Whilst evidence indicates that one O2 sensitive K+ channel, BKCa, may be regulated by gasotransmitters (CO and H2S) in an O2-dependent manner, other studies now indicate that activation of AMP-activated protein kinase (AMPK) accounts for inhibition of both BKCa and 'leak' O2 sensitive K+ channels, and perhaps also other O2 sensitive K+ channels reported in different species. We propose that type I cell AMPK activation occurs as a result of inhibition of mitochondrial oxidative phosphorylation, and does not require increased production of reactive oxygen species. Thus, AMPK activation provides the basis for unifying the 'membrane' and 'mitochondrial' hypotheses, previously regarded as disparate, to account for hypoxic chemotransduction.
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Affiliation(s)
- Chris Peers
- Division of Cardiovascular and Neuronal Remodelling, Leeds Institute for Genetics, Health and Therapeutics (LIGHT), Faculty of Medicine and Health, Worsley Building (Level 10), University of Leeds, Clarendon Way, Leeds LS2 9JT, UK.
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45
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Enyedi P, Czirják G. Molecular background of leak K+ currents: two-pore domain potassium channels. Physiol Rev 2010; 90:559-605. [PMID: 20393194 DOI: 10.1152/physrev.00029.2009] [Citation(s) in RCA: 642] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Two-pore domain K(+) (K(2P)) channels give rise to leak (also called background) K(+) currents. The well-known role of background K(+) currents is to stabilize the negative resting membrane potential and counterbalance depolarization. However, it has become apparent in the past decade (during the detailed examination of the cloned and corresponding native K(2P) channel types) that this primary hyperpolarizing action is not performed passively. The K(2P) channels are regulated by a wide variety of voltage-independent factors. Basic physicochemical parameters (e.g., pH, temperature, membrane stretch) and also several intracellular signaling pathways substantially and specifically modulate the different members of the six K(2P) channel subfamilies (TWIK, TREK, TASK, TALK, THIK, and TRESK). The deep implication in diverse physiological processes, the circumscribed expression pattern of the different channels, and the interesting pharmacological profile brought the K(2P) channel family into the spotlight. In this review, we focus on the physiological roles of K(2P) channels in the most extensively investigated cell types, with special emphasis on the molecular mechanisms of channel regulation.
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Affiliation(s)
- Péter Enyedi
- Department of Physiology, Semmelweis University, Budapest, Hungary.
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46
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Ortiz FC, Varas R. Muscarinic modulation of TASK-like background potassium channel in rat carotid body chemoreceptor cells. Brain Res 2010; 1323:74-83. [DOI: 10.1016/j.brainres.2010.01.091] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 01/29/2010] [Accepted: 01/30/2010] [Indexed: 10/19/2022]
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