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Kostritskaia Y, Klüssendorf M, Pan YE, Hassani Nia F, Kostova S, Stauber T. Physiological Functions of the Volume-Regulated Anion Channel VRAC/LRRC8 and the Proton-Activated Chloride Channel ASOR/TMEM206. Handb Exp Pharmacol 2024; 283:181-218. [PMID: 37468723 DOI: 10.1007/164_2023_673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Volume-regulated anion channels (VRACs) and the acid-sensitive outwardly rectifying anion channel (ASOR) mediate flux of chloride and small organic anions. Although known for a long time, they were only recently identified at the molecular level. VRACs are heteromers consisting of LRRC8 proteins A to E. Combining the essential LRRC8A with different LRRC8 paralogues changes key properties of VRAC such as conductance or substrate selectivity, which is how VRACs are involved in multiple physiological functions including regulatory volume decrease, cell proliferation and migration, cell death, purinergic signalling, fat and glucose metabolism, insulin signalling, and spermiogenesis. VRACs are also involved in pathological conditions, such as the neurotoxic release of glutamate and aspartate. Certain VRACs are also permeable to larger, organic anions, including antibiotics and anti-cancer drugs, making them an interesting therapeutic target. ASOR, also named proton-activated chloride channel (PAC), is formed by TMEM206 homotrimers on the plasma membrane and on endosomal compartments where it mediates chloride flux in response to extracytosolic acidification and plays a role in the shrinking and maturation of macropinosomes. ASOR has been shown to underlie neuronal swelling which causes cell death after stroke as well as promoting the metastasis of certain cancers, making them intriguing therapeutic targets as well.
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Affiliation(s)
- Yulia Kostritskaia
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Malte Klüssendorf
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Yingzhou Edward Pan
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Fatemeh Hassani Nia
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Simona Kostova
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Tobias Stauber
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany.
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2
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Sarkar S. Microglial ion channels: Key players in non-cell autonomous neurodegeneration. Neurobiol Dis 2022; 174:105861. [PMID: 36115552 PMCID: PMC9617777 DOI: 10.1016/j.nbd.2022.105861] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 08/26/2022] [Accepted: 09/12/2022] [Indexed: 12/03/2022] Open
Abstract
Neuroinflammation is a critical pathophysiological hallmark of neurodegenerative disorders, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and traumatic brain injury (TBI). Microglia, the first responders of the brain, are the drivers of this neuroinflammation. Microglial activation, leading to induction of pro-inflammatory factors, like Interleukin 1-β (IL-1β), Tumor necrosis factor-α (TNFα), nitrites, and others, have been shown to induce neurodegeneration. Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce the risk of developing PD, but the mechanism underlying the microglial activation is still under active research. Recently, microglial ion channels have come to the forefront as potential drug targets in multiple neurodegenerative disorders, including AD and PD. Microglia expresses a variety of ion channels, including potassium channels, calcium channels, chloride channels, sodium channels, and proton channels. The diversity of channels present on microglia is responsible for the dynamic nature of these immune cells of the brain. These ion channels regulate microglial proliferation, chemotaxis, phagocytosis, antigen recognition and presentation, apoptosis, and cell signaling leading to inflammation, among other critical functions. Understanding the role of these ion channels and the signaling mechanism these channels regulate under pathological conditions is an active area of research. This review will be focusing on the roles of different microglial ion channels, and their potential role in regulating microglial functions in neurodegenerative disorders.
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Affiliation(s)
- Souvarish Sarkar
- Dept. of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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Wang Z, Li Y, Zeng Z, Guo S, Chen W, Luo Y. Leucine-rich repeat containing 8A contributes to the expansion of The potential role of leucine-rich repeat-containing protein 8A in central nervous system: current situation and prospect. Neuroscience 2022; 488:122-131. [PMID: 35276302 DOI: 10.1016/j.neuroscience.2022.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/24/2022] [Accepted: 03/01/2022] [Indexed: 12/12/2022]
Abstract
Cell swelling usually initiates the regulatory volume decrease (RVD) process mediated mainly by volume-regulated anion channels (VRACs), which are formed by multiple different leucine-rich repeat-containing protein 8 (LRRC8) family members. VRAC currents have been widely recorded in astrocytes, neurons and microglia in the brain, and VRACs have been suggested to be involved in the important pathogenesis of cell swelling-related central nervous system (CNS) diseases, such as ischemic stroke, epilepsy and epileptogenesis, glioblastoma (GBM), and so on. Recently, the increasing studies started to focus on LRRC8A (SWELL1), an obligatory subunit of VRAC indentified in 2014, which may be the key target to regulate the VRAC functions. After cerebral ischemia, the swollen astrocytes, neurons and microglia can activate LRRC8A-dependent VRACs, which may respectively promote the release of excitatory amino acids (EAA), interaction with ionotropic glutamate receptors, and regulating inflammation, suggesting the pleiotropic roles of LRRC8A in swollen brain cells. For the treatment of cell swelling-related CNS diseases, specific targeting LRRC8A may be a superior strategy to inhibit swollen-induced VRAC hyperactivity without blocking the normal VRAC function.
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Affiliation(s)
- Zhuo Wang
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan 430071, Hubei, China; Wuhan Institute for Neuroscience and Neuroengineering, South-Central University for Nationalities, Wuhan 430074, Hubei, China
| | - Yunhui Li
- National Key Laboratory of Medical Immunology & Institute of Immunology, Second Military Medical University, Shanghai 200433, China
| | - Zhikun Zeng
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, Hubei, China
| | - Shuang Guo
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, Hubei, China
| | - Wei Chen
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, Hubei, China
| | - Yi Luo
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, Hubei, China.
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The Important Role of Ion Transport System in Cervical Cancer. Int J Mol Sci 2021; 23:ijms23010333. [PMID: 35008759 PMCID: PMC8745646 DOI: 10.3390/ijms23010333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 12/26/2021] [Accepted: 12/27/2021] [Indexed: 12/15/2022] Open
Abstract
Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca2+ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl− channels and K+-Cl− cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca2+ homeostasis, the Ca2+ store sensor STIM molecules and plasma membrane Ca2+ channel Orai proteins, the predominant Ca2+ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.
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Cojocaru A, Burada E, Bălșeanu AT, Deftu AF, Cătălin B, Popa-Wagner A, Osiac E. Roles of Microglial Ion Channel in Neurodegenerative Diseases. J Clin Med 2021; 10:jcm10061239. [PMID: 33802786 PMCID: PMC8002406 DOI: 10.3390/jcm10061239] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/02/2021] [Accepted: 03/11/2021] [Indexed: 12/15/2022] Open
Abstract
As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.
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Affiliation(s)
- Alexandru Cojocaru
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
- Experimental Research Center for Normal and Pathological Aging, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania
| | - Emilia Burada
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
| | - Adrian-Tudor Bălșeanu
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
- Experimental Research Center for Normal and Pathological Aging, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania
| | - Alexandru-Florian Deftu
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), CH-1011 Lausanne, Switzerland;
- Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), CH-1011 Lausanne, Switzerland
| | - Bogdan Cătălin
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
- Experimental Research Center for Normal and Pathological Aging, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania
- Correspondence: (B.C.); (A.P.-W.)
| | - Aurel Popa-Wagner
- Chair of Vascular Neurology, Dementia and Ageing Research, University Hospital Essen, 45147 Essen, Germany
- Correspondence: (B.C.); (A.P.-W.)
| | - Eugen Osiac
- Department of Biophysics, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania;
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Gattlen C, Deftu AF, Tonello R, Ling Y, Berta T, Ristoiu V, Suter MR. The inhibition of Kir2.1 potassium channels depolarizes spinal microglial cells, reduces their proliferation, and attenuates neuropathic pain. Glia 2020; 68:2119-2135. [PMID: 32220118 DOI: 10.1002/glia.23831] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 03/11/2020] [Accepted: 03/13/2020] [Indexed: 11/11/2022]
Abstract
Spinal microglia change their phenotype and proliferate after nerve injury, contributing to neuropathic pain. For the first time, we have characterized the electrophysiological properties of microglia and the potential role of microglial potassium channels in the spared nerve injury (SNI) model of neuropathic pain. We observed a strong increase of inward currents restricted at 2 days after injury associated with hyperpolarization of the resting membrane potential (RMP) in microglial cells compared to later time-points and naive animals. We identified pharmacologically and genetically the current as being mediated by Kir2.1 ion channels whose expression at the cell membrane is increased 2 days after SNI. The inhibition of Kir2.1 with ML133 and siRNA reversed the RMP hyperpolarization and strongly reduced the currents of microglial cells 2 days after SNI. These electrophysiological changes occurred coincidentally to the peak of microglial proliferation following nerve injury. In vitro, ML133 drastically reduced the proliferation of BV2 microglial cell line after both 2 and 4 days in culture. In vivo, the intrathecal injection of ML133 significantly attenuated the proliferation of microglia and neuropathic pain behaviors after nerve injury. In summary, our data implicate Kir2.1-mediated microglial proliferation as an important therapeutic target in neuropathic pain.
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Affiliation(s)
- Christophe Gattlen
- Pain Center, Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CHUV), Lausanne, Switzerland.,Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland
| | - Alexandru-Florian Deftu
- Pain Center, Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CHUV), Lausanne, Switzerland.,Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland.,Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Raquel Tonello
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Yuejuan Ling
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA.,Pain Research Laboratory, Institute of Nautical Medicine, Jiangsu Key Laboratory of Neurodegeneration, University of Nantong, Nantong, Jiangsu, China
| | - Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Violeta Ristoiu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Marc René Suter
- Pain Center, Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CHUV), Lausanne, Switzerland.,Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland.,Department of Fundamental Neurosciences, Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland
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Upregulation of Potassium Voltage-Gated Channel Subfamily J Member 2 Levels in the Lungs of Patients with Idiopathic Pulmonary Fibrosis. Can Respir J 2020; 2020:3406530. [PMID: 32184906 PMCID: PMC7061125 DOI: 10.1155/2020/3406530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 01/23/2020] [Indexed: 01/23/2023] Open
Abstract
Background Fibroblast dysfunction is the main pathogenic mechanism underpinning idiopathic pulmonary fibrosis (IPF). Potassium voltage-gated channel subfamily J member 2 (KCNJ2) plays critical roles in the proliferation of myofibroblasts and in the development of cardiac fibrosis. Objectives This study aimed to evaluate the role of KCNJ2 in IPF. Methods KCNJ2 mRNA expression was measured using real-time PCR in fibroblasts from IPF patients and normal controls (NCs). Protein concentrations were measured by ELISA in bronchoalveolar lavage (BAL) fluid obtained from NCs (n = 30), IPF (n = 30), IPF (n = 30), IPF (n = 30), IPF (n = 30), IPF ( Results KCNJ2 mRNA expression was measured using real-time PCR in fibroblasts from IPF patients and normal controls (NCs). Protein concentrations were measured by ELISA in bronchoalveolar lavage (BAL) fluid obtained from NCs (n = 30), IPF (n = 30), IPF (p < 0.001). KCNJ2 protein levels in BAL fluid were significantly higher in IPF (6.587 [1.441–26.01] ng/mL) than in NCs (0.084 [0.00–0.260] ng/mL, p < 0.001). KCNJ2 protein levels in BAL fluid were significantly higher in IPF (6.587 [1.441–26.01] ng/mL) than in NCs (0.084 [0.00–0.260] ng/mL, p < 0.001). KCNJ2 protein levels in BAL fluid were significantly higher in IPF (6.587 [1.441–26.01] ng/mL) than in NCs (0.084 [0.00–0.260] ng/mL, p < 0.001). KCNJ2 protein levels in BAL fluid were significantly higher in IPF (6.587 [1.441–26.01] ng/mL) than in NCs (0.084 [0.00–0.260] ng/mL, p < 0.001). KCNJ2 protein levels in BAL fluid were significantly higher in IPF (6.587 [1.441–26.01] ng/mL) than in NCs (0.084 [0.00–0.260] ng/mL, Conclusion KCNJ2 may participate in the development of IPF, and its protein level may be a candidate diagnostic and therapeutic molecule for IPF.
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Chen L, König B, Liu T, Pervaiz S, Razzaque YS, Stauber T. More than just a pressure relief valve: physiological roles of volume-regulated LRRC8 anion channels. Biol Chem 2019; 400:1481-1496. [DOI: 10.1515/hsz-2019-0189] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/27/2019] [Indexed: 12/29/2022]
Abstract
Abstract
The volume-regulated anion channel (VRAC) is a key player in the volume regulation of vertebrate cells. This ubiquitously expressed channel opens upon osmotic cell swelling and potentially other cues and releases chloride and organic osmolytes, which contributes to regulatory volume decrease (RVD). A plethora of studies have proposed a wide range of physiological roles for VRAC beyond volume regulation including cell proliferation, differentiation and migration, apoptosis, intercellular communication by direct release of signaling molecules and by supporting the exocytosis of insulin. VRAC was additionally implicated in pathological states such as cancer therapy resistance and excitotoxicity under ischemic conditions. Following extensive investigations, 5 years ago leucine-rich repeat-containing family 8 (LRRC8) heteromers containing LRRC8A were identified as the pore-forming components of VRAC. Since then, molecular biological approaches have allowed further insight into the biophysical properties and structure of VRAC. Heterologous expression, siRNA-mediated downregulation and genome editing in cells, as well as the use of animal models have enabled the assessment of the proposed physiological roles, together with the identification of new functions including spermatogenesis and the uptake of antibiotics and platinum-based cancer drugs. This review discusses the recent molecular biological insights into the physiology of VRAC in relation to its previously proposed roles.
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Affiliation(s)
- Lingye Chen
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Benjamin König
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Tianbao Liu
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Sumaira Pervaiz
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Yasmin S. Razzaque
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Tobias Stauber
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
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Chen Y, Shi Y, Wang G, Li Y, Cheng L, Wang Y. Memantine selectively prevented the induction of dynamic allodynia by blocking Kir2.1 channel and inhibiting the activation of microglia in spinal dorsal horn of mice in spared nerve injury model. Mol Pain 2019; 15:1744806919838947. [PMID: 30845882 PMCID: PMC6487752 DOI: 10.1177/1744806919838947] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Background Memantine is one of the important clinical medications in treating moderate to severe Alzheimer disease. The effect of memantine on preventing or treating punctate allodynia has been thoroughly studied but not on the induction of dynamic allodynia. The aim of this study is to investigate whether memantine could prevent the induction of dynamic allodynia and its underlying spinal mechanisms. Results (1) In in vivo spared nerve injury pain model, pretreatment with memantine at a lower dose (10 nmol, intrathecal; memantine-10) selectively prevented the induction of dynamic allodynia but not the punctate allodynia. (2) Pretreatment with either MK801-10 (MK801-10 nmol, intrathecal) or higher dose of memantine (30 nmol, intrathecal; memantine-30) prevented the induction of both dynamic and punctate allodynia. (3) Memantine-10 showed significant effect on the inhibition of the spared nerve injury-induced overactivation of microglia in spinal dorsal horn. (4) In contrast, in complete freund′s adjuvant (CFA) model, memantine-10 neither affected the CFA injection-induced activation of microglia in spinal dorsal horn nor the induction of dynamic allodynia. (5) Immunohistological studies showed Kir2.1 channel distributed widely and co-localized with microglia in the spinal dorsal horn of mice. (6) Pretreatment with either minocycline, a microglia inhibitor, or ML133, a Kir2.1 inhibitor, both selectively prevented the overactivation of microglia in spinal dorsal horn and the induction of dynamic allodynia following spared nerve injury. Conclusion The selective inhibitory effect on the induction of dynamic allodynia in spared nerve injury model by low dose of the memantine (memantine-10) was tightly correlated with the blockade of microglia Kir2.1 channel to suppress the microglia activation.
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Affiliation(s)
- Yangyang Chen
- 1 Neurology Department, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yiqian Shi
- 1 Neurology Department, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Guoxiang Wang
- 1 Neurology Department, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yimei Li
- 1 Neurology Department, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Longzhen Cheng
- 1 Neurology Department, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yun Wang
- 1 Neurology Department, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
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The Volume-Regulated Anion Channel LRRC8/VRAC Is Dispensable for Cell Proliferation and Migration. Int J Mol Sci 2019; 20:ijms20112663. [PMID: 31151189 PMCID: PMC6600467 DOI: 10.3390/ijms20112663] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 02/06/2023] Open
Abstract
Cells possess the capability to adjust their volume for various physiological processes, presumably including cell proliferation and migration. The volume-regulated anion channel (VRAC), formed by LRRC8 heteromers, is critically involved in regulatory volume decrease of vertebrate cells. The VRAC has also been proposed to play a role in cell cycle progression and cellular motility. Indeed, recent reports corroborated this notion, with potentially important implications for the VRAC in cancer progression. In the present study, we examined the role of VRAC during cell proliferation and migration in several cell types, including C2C12 myoblasts, human colon cancer HCT116 cells, and U251 and U87 glioblastoma cells. Surprisingly, neither pharmacological inhibition of VRAC with 4-[(2-Butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid (DCPIB), carbenoxolone or 5-nitro-2-(3-phenylpropyl-amino)benzoic acid (NPPB), nor siRNA-mediated knockdown or gene knockout of the essential VRAC subunit LRRC8A affected cell growth and motility in any of the investigated cell lines. Additionally, we found no effect of the VRAC inhibition using siRNA treatment or DCPIB on PI3K/Akt signaling in glioblastoma cells. In summary, our work suggests that VRAC is dispensable for cell proliferation or migration.
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11
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Thei L, Imm J, Kaisis E, Dallas ML, Kerrigan TL. Microglia in Alzheimer's Disease: A Role for Ion Channels. Front Neurosci 2018; 12:676. [PMID: 30323735 PMCID: PMC6172337 DOI: 10.3389/fnins.2018.00676] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 09/07/2018] [Indexed: 12/11/2022] Open
Abstract
Alzheimer's disease is the most common form of dementia, it is estimated to affect over 40 million people worldwide. Classically, the disease has been characterized by the neuropathological hallmarks of aggregated extracellular amyloid-β and intracellular paired helical filaments of hyperphosphorylated tau. A wealth of evidence indicates a pivotal role for the innate immune system, such as microglia, and inflammation in the pathology of Alzheimer's disease. The over production and aggregation of Alzheimer's associated proteins results in chronic inflammation and disrupts microglial clearance of these depositions. Despite being non-excitable, microglia express a diverse array of ion channels which shape their physiological functions. In support of this, there is a growing body of evidence pointing to the involvement of microglial ion channels contributing to neurodegenerative diseases such as Alzheimer's disease. In this review, we discuss the evidence for an array of microglia ion channels and their importance in modulating microglial homeostasis and how this process could be disrupted in Alzheimer's disease. One promising avenue for assessing the role that microglia play in the initiation and progression of Alzheimer's disease is through using induced pluripotent stem cell derived microglia. Here, we examine what is already understood in terms of the molecular underpinnings of inflammation in Alzheimer's disease, and the utility that inducible pluripotent stem cell derived microglia may have to advance this knowledge. We outline the variability that occurs between the use of animal and human models with regards to the importance of microglial ion channels in generating a relevant functional model of brain inflammation. Overcoming these hurdles will be pivotal in order to develop new drug targets and progress our understanding of the pathological mechanisms involved in Alzheimer's disease.
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Affiliation(s)
- Laura Thei
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Jennifer Imm
- University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
| | - Eleni Kaisis
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Mark L Dallas
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Talitha L Kerrigan
- University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
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Lively S, Lam D, Wong R, Schlichter LC. Comparing Effects of Transforming Growth Factor β1 on Microglia From Rat and Mouse: Transcriptional Profiles and Potassium Channels. Front Cell Neurosci 2018; 12:115. [PMID: 29780305 PMCID: PMC5946019 DOI: 10.3389/fncel.2018.00115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/11/2018] [Indexed: 12/02/2022] Open
Abstract
The cytokine, transforming growth factor β1 (TGFβ1), is up-regulated after central nervous system (CNS) injuries or diseases involving microglial activation, and it has been proposed as a therapeutic agent for treating neuroinflammation. Microglia can produce and respond to TGFβ1. While rats and mice are commonly used for studying neuroinflammation, very few reports directly compare them. Such studies are important for improving pre-clinical studies and furthering translational progress in developing therapeutic interventions. After intracerebral hemorrhage (ICH) in the rat striatum, the TGFβ1 receptor was highly expressed on microglia/macrophages within the hematoma. We recently found species similarities and differences in response to either a pro-inflammatory (interferon-γ, IFN-γ, +tumor necrosis factor, TNF-α) or anti-inflammatory interleukin-4 (IL-4) stimulus. Here, we assessed whether rat and mouse microglia differ in their responses to TGFβ1. Microglia were isolated from Sprague-Dawley rats and C57BL/6 mice and treated with TGFβ1. We quantified changes in expression of >50 genes, in their morphology, proliferation, apoptosis and in three potassium channels that are considered therapeutic targets. Many inflammatory mediators, immune receptors and modulators showed species similarities, but notable differences included that, for some genes, only one species responded (e.g., Il4r, Il10, Tgfbr2, colony-stimulating factor receptor (Csf1r), Itgam, suppressor of cytokine signaling 1 (Socs1), toll-like receptors 4 (Tlr4), P2rx7, P2ry12), and opposite responses were seen for others (Tgfb1, Myc, Ifngr1). In rat only, TGFβ1 affected microglial morphology and proliferation, but there was no apoptosis in either species. In both species, TGFβ1 dramatically increased Kv1.3 channel expression and current (no effects on Kir2.1). KCa3.1 showed opposite species responses: the current was low in unstimulated rat microglia and greatly increased by TGFβ1 but higher in control mouse cells and decreased by TGFβ1. Finally, we compared TGFβ1 and IL10 (often considered similar anti-inflammatory stimuli) and found many different responses in both species. Overall, the numerous species differences should be considered when characterizing neuroinflammation and microglial activation in vitro and in vivo, and when targeting potassium channels.
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Affiliation(s)
- Starlee Lively
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada
| | - Doris Lam
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Raymond Wong
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Lyanne C Schlichter
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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13
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Wilson CS, Mongin AA. The signaling role for chloride in the bidirectional communication between neurons and astrocytes. Neurosci Lett 2018; 689:33-44. [PMID: 29329909 DOI: 10.1016/j.neulet.2018.01.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 01/04/2018] [Accepted: 01/05/2018] [Indexed: 01/01/2023]
Abstract
It is well known that the electrical signaling in neuronal networks is modulated by chloride (Cl-) fluxes via the inhibitory GABAA and glycine receptors. Here, we discuss the putative contribution of Cl- fluxes and intracellular Cl- to other forms of information transfer in the CNS, namely the bidirectional communication between neurons and astrocytes. The manuscript (i) summarizes the generic functions of Cl- in cellular physiology, (ii) recaps molecular identities and properties of Cl- transporters and channels in neurons and astrocytes, and (iii) analyzes emerging studies implicating Cl- in the modulation of neuroglial communication. The existing literature suggests that neurons can alter astrocytic Cl- levels in a number of ways; via (a) the release of neurotransmitters and activation of glial transporters that have intrinsic Cl- conductance, (b) the metabotropic receptor-driven changes in activity of the electroneutral cation-Cl- cotransporter NKCC1, and (c) the transient, activity-dependent changes in glial cell volume which open the volume-regulated Cl-/anion channel VRAC. Reciprocally, astrocytes are thought to alter neuronal [Cl-]i through either (a) VRAC-mediated release of the inhibitory gliotransmitters, GABA and taurine, which open neuronal GABAA and glycine receptor/Cl- channels, or (b) the gliotransmitter-driven stimulation of NKCC1. The most important recent developments in this area are the identification of the molecular composition and functional heterogeneity of brain VRAC channels, and the discovery of a new cytosolic [Cl-] sensor - the Wnk family protein kinases. With new work in the field, our understanding of the role of Cl- in information processing within the CNS is expected to be significantly updated.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States; Department of Biophysics and Functional Diagnostics, Siberian State Medical University, Tomsk, Russian Federation.
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14
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Chen YJ, Nguyen HM, Maezawa I, Jin LW, Wulff H. Inhibition of the potassium channel Kv1.3 reduces infarction and inflammation in ischemic stroke. Ann Clin Transl Neurol 2017; 5:147-161. [PMID: 29468176 PMCID: PMC5817832 DOI: 10.1002/acn3.513] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/10/2017] [Accepted: 11/20/2017] [Indexed: 12/26/2022] Open
Abstract
Objective Inhibitors of the voltage‐gated K+ channel Kv1.3 are currently in development as immunomodulators for the treatment of autoimmune diseases. As Kv1.3 is also expressed on microglia and has been shown to be specifically up‐regulated on “M1‐like” microglia, we here tested the therapeutic hypothesis that the brain‐penetrant small‐molecule Kv1.3‐inhibitor PAP‐1 reduces secondary inflammatory damage after ischemia/reperfusion. Methods We studied microglial Kv1.3 expression using electrophysiology and immunohistochemistry, and evaluated PAP‐1 in hypoxia‐exposed organotypic hippocampal slices and in middle cerebral artery occlusion (MCAO) with 8 days of reperfusion in both adult male C57BL/6J mice (60 min MCAO) and adult male Wistar rats (90 min MCAO). In both models, PAP‐1 administration was started 12 h after reperfusion. Results We observed Kv1.3 staining on activated microglia in ischemic infarcts in mice, rats, and humans and found higher Kv1.3 current densities in acutely isolated microglia from the infarcted hemisphere than in microglia isolated from the contralateral hemisphere of MCAO mice. PAP‐1 reduced microglia activation and increased neuronal survival in hypoxia‐exposed hippocampal slices as effectively as minocycline. In mouse MCAO, PAP‐1 dose‐dependently reduced infarct area, improved neurological deficit score, and reduced brain levels of IL‐1β and IFN‐γ without affecting IL‐10 and brain‐derived nerve growth factor (BDNF) levels or inhibiting ongoing phagocytosis. The beneficial effects on infarct area and neurological deficit score were reproduced in rats providing confirmation in a second species. Interpretation Our findings suggest that Kv1.3 constitutes a promising therapeutic target for preferentially inhibiting “M1‐like” inflammatory microglia/macrophage functions in ischemic stroke.
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Affiliation(s)
- Yi-Je Chen
- Department of Pharmacology University of California Davis 95616 California
| | - Hai M Nguyen
- Department of Pharmacology University of California Davis 95616 California
| | - Izumi Maezawa
- Department of Pathology and Laboratory Medicine University of California Davis, Sacramento 95817 California.,M.I.N.D. Institute University of California Davis 95817 California
| | - Lee-Way Jin
- Department of Pathology and Laboratory Medicine University of California Davis, Sacramento 95817 California.,M.I.N.D. Institute University of California Davis 95817 California
| | - Heike Wulff
- Department of Pharmacology University of California Davis 95616 California
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15
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Pérez-García MT, Cidad P, López-López JR. The secret life of ion channels: Kv1.3 potassium channels and proliferation. Am J Physiol Cell Physiol 2017; 314:C27-C42. [PMID: 28931540 DOI: 10.1152/ajpcell.00136.2017] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Kv1.3 channels are involved in the switch to proliferation of normally quiescent cells, being implicated in the control of cell cycle in many different cell types and in many different ways. They modulate membrane potential controlling K+ fluxes, sense changes in potential, and interact with many signaling molecules through their intracellular domains. From a mechanistic point of view, we can describe the role of Kv1.3 channels in proliferation with at least three different models. In the "membrane potential model," membrane hyperpolarization resulting from Kv1.3 activation provides the driving force for Ca2+ influx required to activate Ca2+-dependent transcription. This model explains most of the data obtained from several cells from the immune system. In the "voltage sensor model," Kv1.3 channels serve mainly as sensors that transduce electrical signals into biochemical cascades, independently of their effect on membrane potential. Kv1.3-dependent proliferation of vascular smooth muscle cells (VSMCs) could fit this model. Finally, in the "channelosome balance model," the master switch determining proliferation may be related to the control of the Kv1.3 to Kv1.5 ratio, as described in glial cells and also in VSMCs. Since the three mechanisms cannot function independently, these models are obviously not exclusive. Nevertheless, they could be exploited differentially in different cells and tissues. This large functional flexibility of Kv1.3 channels surely gives a new perspective on their functions beyond their elementary role as ion channels, although a conclusive picture of the mechanisms involved in Kv1.3 signaling to proliferation is yet to be reached.
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Affiliation(s)
- M Teresa Pérez-García
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas , Valladolid , Spain
| | - Pilar Cidad
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas , Valladolid , Spain
| | - José R López-López
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas , Valladolid , Spain
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16
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Lam D, Lively S, Schlichter LC. Responses of rat and mouse primary microglia to pro- and anti-inflammatory stimuli: molecular profiles, K + channels and migration. J Neuroinflammation 2017; 14:166. [PMID: 28830445 PMCID: PMC5567442 DOI: 10.1186/s12974-017-0941-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 08/13/2017] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Acute CNS damage is commonly studied using rat and mouse models, but increasingly, molecular analysis is finding species differences that might affect the ability to translate findings to humans. Microglia can undergo complex molecular and functional changes, often studied by in vitro responses to discrete activating stimuli. There is considerable evidence that pro-inflammatory (M1) activation can exacerbate tissue damage, while anti-inflammatory (M2) states help resolve inflammation and promote tissue repair. However, in assessing potential therapeutic targets for controlling inflammation, it is crucial to determine whether rat and mouse microglia respond the same. METHODS Primary microglia from Sprague-Dawley rats and C57BL/6 mice were cultured, then stimulated with interferon-γ + tumor necrosis factor-α (I + T; M1 activation), interleukin (IL)-4 (M2a, alternative activation), or IL-10 (M2c, acquired deactivation). To profile their activation responses, NanoString was used to monitor messenger RNA (mRNA) expression of numerous pro- and anti-inflammatory mediators, microglial markers, immunomodulators, and other molecules. Western analysis was used to measure selected proteins. Two potential targets for controlling inflammation-inward- and outward-rectifier K+ channels (Kir2.1, Kv1.3)-were examined (mRNA, currents) and specific channel blockers were applied to determine their contributions to microglial migration in the different activation states. RESULTS Pro-inflammatory molecules increased after I + T treatment but there were several qualitative and quantitative differences between the species (e.g., iNOS and nitric oxide, COX-2). Several molecules commonly associated with an M2a state differed between species or they were induced in additional activation states (e.g., CD206, ARG1). Resting levels and/or responses of several microglial markers (Iba1, CD11b, CD68) differed with the activation state, species, or both. Transcripts for several Kir2 and Kv1 family members were detected in both species. However, the current amplitudes (mainly Kir2.1 and Kv1.3) depended on activation state and species. Treatment-induced changes in morphology and migratory capacity were similar between the species (migration reduced by I + T, increased by IL-4 or IL-10). In both species, Kir2.1 block reduced migration and Kv1.3 block increased it, regardless of activation state; thus, these channels might affect microglial migration to damage sites. CONCLUSIONS Caution is recommended in generalizing molecular and functional responses of microglia to activating stimuli between species.
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Affiliation(s)
- Doris Lam
- Genes and Development Division, Krembil Research Institute, University Health Network, Krembil Discovery Tower, Room 7KD417, 60 Leonard Avenue, Toronto, ON, M5T 2S8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Starlee Lively
- Genes and Development Division, Krembil Research Institute, University Health Network, Krembil Discovery Tower, Room 7KD417, 60 Leonard Avenue, Toronto, ON, M5T 2S8, Canada
| | - Lyanne C Schlichter
- Genes and Development Division, Krembil Research Institute, University Health Network, Krembil Discovery Tower, Room 7KD417, 60 Leonard Avenue, Toronto, ON, M5T 2S8, Canada. .,Department of Physiology, University of Toronto, Toronto, ON, Canada.
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17
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Murana E, Pagani F, Basilico B, Sundukova M, Batti L, Di Angelantonio S, Cortese B, Grimaldi A, Francioso A, Heppenstall P, Bregestovski P, Limatola C, Ragozzino D. ATP release during cell swelling activates a Ca 2+-dependent Cl - current by autocrine mechanism in mouse hippocampal microglia. Sci Rep 2017. [PMID: 28646166 PMCID: PMC5482828 DOI: 10.1038/s41598-017-04452-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Microglia cells, resident immune cells of the brain, survey brain parenchyma by dynamically extending and retracting their processes. Cl− channels, activated in the cellular response to stretch/swelling, take part in several functions deeply connected with microglia physiology, including cell shape changes, proliferation, differentiation and migration. However, the molecular identity and functional properties of these Cl− channels are largely unknown. We investigated the properties of swelling-activated currents in microglial from acute hippocampal slices of Cx3cr1+/GFP mice by whole-cell patch-clamp and imaging techniques. The exposure of cells to a mild hypotonic medium, caused an outward rectifying current, developing in 5–10 minutes and reverting upon stimulus washout. This current, required for microglia ability to extend processes towards a damage signal, was carried mainly by Cl− ions and dependent on intracellular Ca2+. Moreover, it involved swelling-induced ATP release. We identified a purine-dependent mechanism, likely constituting an amplification pathway of current activation: under hypotonic conditions, ATP release triggered the Ca2+-dependent activation of anionic channels by autocrine purine receptors stimulation. Our study on native microglia describes for the first time the functional properties of stretch/swelling-activated currents, representing a key element in microglia ability to monitor the brain parenchyma.
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Affiliation(s)
- E Murana
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - F Pagani
- Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy.
| | - B Basilico
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - M Sundukova
- Mouse Biology Unit, EMBL, Monterotondo, Italy
| | - L Batti
- Mouse Biology Unit, EMBL, Monterotondo, Italy
| | - S Di Angelantonio
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy.,Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy
| | - B Cortese
- CNR NANOTEC - Istituto di Nanotecnologia, Department of Physics, University Sapienza, Rome, Italy
| | - A Grimaldi
- Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy
| | - A Francioso
- Department of Biochemistry, "Sapienza" University of Rome, Rome, Italy
| | | | - P Bregestovski
- Aix Marseille University, Inserm, INS, Institut de Neurosciences des Systèmes, Marseille, France
| | - C Limatola
- IRCCS Neuromed, Via Atinese, Pozzilli, Italy.,Pasteur Institute - Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - D Ragozzino
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy.,IRCCS Neuromed, Via Atinese, Pozzilli, Italy
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18
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Nguyen HM, Grössinger EM, Horiuchi M, Davis KW, Jin LW, Maezawa I, Wulff H. Differential Kv1.3, KCa3.1, and Kir2.1 expression in "classically" and "alternatively" activated microglia. Glia 2016; 65:106-121. [PMID: 27696527 PMCID: PMC5113690 DOI: 10.1002/glia.23078] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 09/15/2016] [Indexed: 11/10/2022]
Abstract
Microglia are highly plastic cells that can assume different phenotypes in response to microenvironmental signals. Lipopolysaccharide (LPS) and interferon-γ (IFN-γ) promote differentiation into classically activated M1-like microglia, which produce high levels of pro-inflammatory cytokines and nitric oxide and are thought to contribute to neurological damage in ischemic stroke and Alzheimer's disease. IL-4 in contrast induces a phenotype associated with anti-inflammatory effects and tissue repair. We here investigated whether these microglia subsets vary in their K+ channel expression by differentiating neonatal mouse microglia into M(LPS) and M(IL-4) microglia and studying their K+ channel expression by whole-cell patch-clamp, quantitative PCR and immunohistochemistry. We identified three major types of K+ channels based on their biophysical and pharmacological fingerprints: a use-dependent, outwardly rectifying current sensitive to the KV 1.3 blockers PAP-1 and ShK-186, an inwardly rectifying Ba2+ -sensitive Kir 2.1 current, and a Ca2+ -activated, TRAM-34-sensitive KCa 3.1 current. Both KV 1.3 and KCa 3.1 blockers inhibited pro-inflammatory cytokine production and iNOS and COX2 expression demonstrating that KV 1.3 and KCa 3.1 play important roles in microglia activation. Following differentiation with LPS or a combination of LPS and IFN-γ microglia exhibited high KV 1.3 current densities (∼50 pA/pF at 40 mV) and virtually no KCa 3.1 and Kir currents, while microglia differentiated with IL-4 exhibited large Kir 2.1 currents (∼ 10 pA/pF at -120 mV). KCa 3.1 currents were generally low but moderately increased following stimulation with IFN-γ or ATP (∼10 pS/pF). This differential K+ channel expression pattern suggests that KV 1.3 and KCa 3.1 inhibitors could be used to inhibit detrimental neuroinflammatory microglia functions. GLIA 2016;65:106-121.
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Affiliation(s)
- Hai M Nguyen
- Department of Pharmacology, University of California, Davis, California
| | - Eva M Grössinger
- Department of Pharmacology, University of California, Davis, California
| | - Makoto Horiuchi
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California.,M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, California
| | - Kyle W Davis
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California
| | - Lee-Way Jin
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California.,M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, California
| | - Izumi Maezawa
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California.,M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, California
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California
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19
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Abstract
Significant progress has been made in identifying physiologically important growth fac tors, receptors, and signal transduction pathways involved in the control of normal and malignant cell proliferation. More recent studies suggest that changes in the proliferative state of a cell are coupled to specific changes in membrane properties, which suggests that there are links between ion channel activity and cell proliferation in both neuronal and non-neuronal cells. Changes in ion channel expression may be necessary to permit cell cycle progression and, ultimately, cell proliferation. The potential mechanisms in volved in the translation of ion channel activity into changes in gene expression are discussed. NEUROSCIENTIST 5:70-73, 1999
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20
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Stauber T. The volume-regulated anion channel is formed by LRRC8 heteromers – molecular identification and roles in membrane transport and physiology. Biol Chem 2016; 396:975-90. [PMID: 25868000 DOI: 10.1515/hsz-2015-0127] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 04/02/2015] [Indexed: 11/15/2022]
Abstract
Cellular volume regulation is fundamental for numerous physiological processes. The volume-regulated anion channel, VRAC, plays a crucial role in regulatory volume decrease. This channel, which is ubiquitously expressed in vertebrates, has been vastly characterized by electrophysiological means. It opens upon cell swelling and conducts chloride and arguably organic osmolytes. VRAC has been proposed to be critically involved in various cellular and organismal functions, including cell proliferation and migration, apoptosis, transepithelial transport, swelling-induced exocytosis and intercellular communication. It may also play a role in pathological states like cancer and ischemia. Despite many efforts, the molecular identity of VRAC had remained elusive for decades, until the recent discovery of heteromers of LRRC8A with other LRRC8 family members as an essential VRAC component. This identification marks a starting point for studies on the structure-function relation, for molecular biological investigations of its cell biology and for re-evaluating the physiological roles of VRAC. This review recapitulates the identification of LRRC8 heteromers as VRAC components, depicts the similarities between LRRC8 proteins and pannexins, and discussed whether VRAC conducts larger osmolytes. Furthermore, proposed physiological functions of VRAC and the present knowledge about the physiological significance of LRRC8 proteins are summarized and collated.
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21
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Echeverry S, Rodriguez MJ, Torres YP. Transient Receptor Potential Channels in Microglia: Roles in Physiology and Disease. Neurotox Res 2016; 30:467-78. [PMID: 27260222 DOI: 10.1007/s12640-016-9632-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 05/12/2016] [Accepted: 05/18/2016] [Indexed: 12/21/2022]
Abstract
Microglia modulate the nervous system cellular environment and induce neuroprotective and neurotoxic effects. Various molecules are involved in these processes, including families of ion channels expressed in microglial cells, such as transient receptor potential (TRP) channels. TRP channels comprise a family of non-selective cation channels that can be activated by mechanical, thermal, and chemical stimuli, and which contribute to the regulation of intracellular calcium concentrations. TRP channels have been shown to be involved in cellular processes such as osmotic regulation, cytokine production, proliferation, activation, cell death, and oxidative stress responses. Given the significance of these processes in microglial activity, studies of TRP channels in microglia have focused on determining their roles in both neuroprotective and neurotoxic processes. TRP channel activity has been proposed to play an important function in neurodegenerative diseases, ischemia, inflammatory responses, and neuropathic pain. Modulation of TRP channel activity may thus be considered as a potential therapeutic strategy for the treatment of various diseases associated with alterations of the central nervous system (CNS). In this review, we describe the expression of different subfamilies of TRP channels in microglia, focusing on their physiological and pathophysiological roles, and consider their potential use as therapeutic targets in CNS diseases.
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Affiliation(s)
- Santiago Echeverry
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40-62, Bogotá, Colombia
| | - María Juliana Rodriguez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40-62, Bogotá, Colombia
| | - Yolima P Torres
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 # 40-62, Bogotá, Colombia.
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22
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Pucca MB, Bertolini TB, Cerni FA, Bordon KCF, Peigneur S, Tytgat J, Bonato VL, Arantes EC. Immunosuppressive evidence of Tityus serrulatus toxins Ts6 and Ts15: insights of a novel K(+) channel pattern in T cells. Immunology 2016; 147:240-50. [PMID: 26595158 DOI: 10.1111/imm.12559] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 11/05/2015] [Accepted: 11/10/2015] [Indexed: 12/25/2022] Open
Abstract
The voltage-gated potassium channel Kv1.3 is a novel target for immunomodulation of autoreactive effector memory T cells, which play a major role in the pathogenesis of autoimmune diseases. In this study, the Ts6 and Ts15 toxins isolated from Tityus serrulatus (Ts) were investigated for their immunosuppressant roles on CD4(+) cell subsets: naive, effector (TEF ), central memory (TCM) and effector memory (TEM). The electrophysiological assays confirmed that both toxins were able to block Kv1.3 channels. Interestingly, an extended Kv channel screening shows that Ts15 blocks Kv2.1 channels. Ts6 and Ts15 significantly inhibit the proliferation of TEM cells and interferon-γ production; however, Ts15 also inhibits other CD4(+) cell subsets (naive, TEF and TCM). Based on the Ts15 inhibitory effect of proliferation of all CD4(+) cell subsets, and based on its blocking effect on Kv2.1, we investigated the Kv2.1 expression in T cells. The assays showed that CD4(+) and CD8(+) cells express the Kv2.1 channels mainly extracellularly with TCM cells expressing the highest number of Kv2.1 channels. We also provide in vivo experimental evidence to the protective effect of Ts6 and Ts15 on delayed-type hypersensitivity reaction. Altogether, this study presents the immunosuppressive behaviour of Ts6 and Ts15 toxins, indicating that these toxins could be promising candidates for autoimmune disease therapy. Moreover, this is the first report illustrating the involvement of a novel K(+) channel subtype, Kv2.1, and its distribution in T-cell subsets.
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Affiliation(s)
- Manuela B Pucca
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Thaís B Bertolini
- Department of Biochemistry and Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Felipe A Cerni
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Karla C F Bordon
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven, Leuven, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven, Leuven, Belgium
| | - Vânia L Bonato
- Department of Biochemistry and Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Eliane C Arantes
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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23
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Wu SY, Chen YW, Tsai SF, Wu SN, Shih YH, Jiang-Shieh YF, Yang TT, Kuo YM. Estrogen ameliorates microglial activation by inhibiting the Kir2.1 inward-rectifier K(+) channel. Sci Rep 2016; 6:22864. [PMID: 26960267 PMCID: PMC4785403 DOI: 10.1038/srep22864] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/22/2016] [Indexed: 02/06/2023] Open
Abstract
Microglial activation is implicated in the pathogenesis of Parkinson's disease (PD). Although the etiology of PD remains unclear, age and male gender are known PD risk factors. By comparing microglia and dopaminergic (DA) neurons in the substantia nigra (SN) of male and female mice of different ages, we found that the degrees of microglial activation and DA neuron loss increased with age in both genders, but were more pronounced in males, as were peripheral lipopolysaccharide (LPS)-induced microglial activation and DA neuron loss. A bilateral ovariectomy (OVX) eliminated the female-associated protection against age- and LPS-induced microglial activation, which suggests that ovary hormones are involved in gender-specific responses. Treating female mice with 17β-estradiol supplements reduced the age-associated microglial activation in OVX mice. Moreover, pretreating mouse BV2 microglial cells with 17β-estradiol inhibited LPS-induced elevation of Toll-like receptor 4, phosphorylated p38, and TNF-α levels. We then examined the effect of 17β-estradiol on inward-rectifier K(+) channel Kir2.1, a known regulator of microglial activation. We found that 17β-estradiol inhibited the Kir2.1 activity of BV2 cells by reducing the probability that the channel would be open. We conclude that age- and inflammation-associated microglial activation is attenuated by ovarian estrogen, because it inhibits Kir2.1.
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Affiliation(s)
- Shih-Ying Wu
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yun-Wen Chen
- Department of Cell Biology and Anatomy, National Cheng Kung University, Tainan, Taiwan.,Department of Chinese Medicine for Post-Baccalaureate, I-Shou University, Kaohsiung, Taiwan
| | - Sheng-Feng Tsai
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University, Tainan, Taiwan
| | - Yao-Hsiang Shih
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Ya-Fen Jiang-Shieh
- Department of Cell Biology and Anatomy, National Cheng Kung University, Tainan, Taiwan
| | - Ting-Ting Yang
- Department of Chinese Medicine for Post-Baccalaureate, I-Shou University, Kaohsiung, Taiwan
| | - Yu-Min Kuo
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan.,Department of Cell Biology and Anatomy, National Cheng Kung University, Tainan, Taiwan
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24
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Mongin AA. Volume-regulated anion channel--a frenemy within the brain. Pflugers Arch 2015; 468:421-41. [PMID: 26620797 DOI: 10.1007/s00424-015-1765-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 11/16/2015] [Accepted: 11/20/2015] [Indexed: 10/22/2022]
Abstract
The volume-regulated anion channel (VRAC) is a ubiquitously expressed yet highly enigmatic member of the superfamily of chloride/anion channels. It is activated by cellular swelling and mediates regulatory cell volume decrease in a majority of vertebrate cells, including those in the central nervous system (CNS). In the brain, besides its crucial role in cellular volume regulation, VRAC is thought to play a part in cell proliferation, apoptosis, migration, and release of physiologically active molecules. Although these roles are not exclusive to the CNS, the relative significance of VRAC in the brain is amplified by several unique aspects of its physiology. One important example is the contribution of VRAC to the release of the excitatory amino acid neurotransmitters glutamate and aspartate. This latter process is thought to have impact on both normal brain functioning (such as astrocyte-neuron signaling) and neuropathology (via promoting the excitotoxic death of neuronal cells in stroke and traumatic brain injury). In spite of much work in the field, the molecular nature of VRAC remained unknown until less than 2 years ago. Two pioneer publications identified VRAC as the heterohexamer formed by the leucine-rich repeat-containing 8 (LRRC8) proteins. These findings galvanized the field and are likely to result in dramatic revisions to our understanding of the place and role of VRAC in the brain, as well as other organs and tissues. The present review briefly recapitulates critical findings in the CNS and focuses on anticipated impact on the LRRC8 discovery on further progress in neuroscience research.
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Affiliation(s)
- Alexander A Mongin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, 47 New Scotland Ave., Albany, NY, 12208, USA.
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25
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Lam D, Schlichter LC. Expression and contributions of the Kir2.1 inward-rectifier K(+) channel to proliferation, migration and chemotaxis of microglia in unstimulated and anti-inflammatory states. Front Cell Neurosci 2015; 9:185. [PMID: 26029054 PMCID: PMC4428136 DOI: 10.3389/fncel.2015.00185] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/28/2015] [Indexed: 12/14/2022] Open
Abstract
When microglia respond to CNS damage, they can range from pro-inflammatory (classical, M1) to anti-inflammatory, alternative (M2) and acquired deactivation states. It is important to determine how microglial functions are affected by these activation states, and to identify molecules that regulate their behavior. Microglial proliferation and migration are crucial during development and following damage in the adult, and both functions are Ca2+-dependent. In many cell types, the membrane potential and driving force for Ca2+ influx are regulated by inward-rectifier K+ channels, including Kir2.1, which is prevalent in microglia. However, it is not known whether Kir2.1 expression and contributions are altered in anti-inflammatory states. We tested the hypothesis that Kir2.1 contributes to Ca2+ entry, proliferation and migration of rat microglia. Kir2.1 (KCNJ2) transcript expression, current amplitude, and proliferation were comparable in unstimulated microglia and following alternative activation (IL-4 stimulated) and acquired deactivation (IL-10 stimulated). To examine functional roles of Kir2.1 in microglia, we first determined that ML133 was more effective than the commonly used blocker, Ba2+; i.e., ML133 was potent (IC50 = 3.5 μM) and voltage independent. Both blockers slightly increased proliferation in unstimulated or IL-4 (but not IL-10)-stimulated microglia. Stimulation with IL-4 or IL-10 increased migration and ATP-induced chemotaxis, and blocking Kir2.1 greatly reduced both but ML133 was more effective. In all three activation states, blocking Kir2.1 with ML133 dramatically reduced Ca2+ influx through Ca2+-release-activated Ca2+ (CRAC) channels. Thus, Kir2.1 channel activity is necessary for microglial Ca2+ signaling and migration under resting and anti-inflammatory states but the channel weakly inhibits proliferation.
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Affiliation(s)
- Doris Lam
- Genetics and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Physiology, University of Toronto Toronto, ON, Canada
| | - Lyanne C Schlichter
- Genetics and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Physiology, University of Toronto Toronto, ON, Canada
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26
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Ferreira R, Wong R, Schlichter LC. KCa3.1/IK1 Channel Regulation by cGMP-Dependent Protein Kinase (PKG) via Reactive Oxygen Species and CaMKII in Microglia: An Immune Modulating Feedback System? Front Immunol 2015; 6:153. [PMID: 25904916 PMCID: PMC4389654 DOI: 10.3389/fimmu.2015.00153] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/23/2015] [Indexed: 01/09/2023] Open
Abstract
The intermediate conductance Ca2+-activated K+ channel, KCa3.1 (IK1/SK4/KCNN4) is widely expressed in the innate and adaptive immune system. KCa3.1 contributes to proliferation of activated T lymphocytes, and in CNS-resident microglia, it contributes to Ca2+ signaling, migration, and production of pro-inflammatory mediators (e.g., reactive oxygen species, ROS). KCa3.1 is under investigation as a therapeutic target for CNS disorders that involve microglial activation and T cells. However, KCa3.1 is post-translationally regulated, and this will determine when and how much it can contribute to cell functions. We previously found that KCa3.1 trafficking and gating require calmodulin (CaM) binding, and this is inhibited by cAMP kinase (PKA) acting at a single phosphorylation site. The same site is potentially phosphorylated by cGMP kinase (PKG), and in some cells, PKG can increase Ca2+, CaM activation, and ROS. Here, we addressed KCa3.1 regulation through PKG-dependent pathways in primary rat microglia and the MLS-9 microglia cell line, using perforated-patch recordings to preserve intracellular signaling. Elevating cGMP increased both the KCa3.1 current and intracellular ROS production, and both were prevented by the selective PKG inhibitor, KT5823. The cGMP/PKG-evoked increase in KCa3.1 current in intact MLS-9 microglia was mediated by ROS, mimicked by applying hydrogen peroxide (H2O2), inhibited by a ROS scavenger (MGP), and prevented by a selective CaMKII inhibitor (mAIP). Similar results were seen in alternative-activated primary rat microglia; their KCa3.1 current required PKG, ROS, and CaMKII, and they had increased ROS production that required KCa3.1 activity. The increase in current apparently did not result from direct effects on the channel open probability (Po) or Ca2+ dependence because, in inside-out patches from transfected HEK293 cells, single-channel activity was not affected by cGMP, PKG, H2O2 at normal or elevated intracellular Ca2+. The regulation pathway we have identified in intact microglia and MLS-9 cells is expected to have broad implications because KCa3.1 plays important roles in numerous cells and tissues.
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Affiliation(s)
- Roger Ferreira
- Genetics and Development Division, Toronto Western Research Institute, University Health Network , Toronto, ON , Canada ; Department of Physiology, University of Toronto , Toronto, ON , Canada
| | - Raymond Wong
- Genetics and Development Division, Toronto Western Research Institute, University Health Network , Toronto, ON , Canada ; Department of Physiology, University of Toronto , Toronto, ON , Canada
| | - Lyanne C Schlichter
- Genetics and Development Division, Toronto Western Research Institute, University Health Network , Toronto, ON , Canada ; Department of Physiology, University of Toronto , Toronto, ON , Canada
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27
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Pagani F, Paolicelli RC, Murana E, Cortese B, Di Angelantonio S, Zurolo E, Guiducci E, Ferreira TA, Garofalo S, Catalano M, D'Alessandro G, Porzia A, Peruzzi G, Mainiero F, Limatola C, Gross CT, Ragozzino D. Defective microglial development in the hippocampus of Cx3cr1 deficient mice. Front Cell Neurosci 2015; 9:111. [PMID: 25873863 PMCID: PMC4379915 DOI: 10.3389/fncel.2015.00111] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/11/2015] [Indexed: 11/13/2022] Open
Abstract
Microglial cells participate in brain development and influence neuronal loss and synaptic maturation. Fractalkine is an important neuronal chemokine whose expression increases during development and that can influence microglia function via the fractalkine receptor, CX3CR1. Mice lacking Cx3cr1 show a variety of neuronal defects thought to be the result of deficient microglia function. Activation of CX3CR1 is important for the proper migration of microglia to sites of injury and into the brain during development. However, little is known about how fractalkine modulates microglial properties during development. Here we examined microglial morphology, response to ATP, and K+ current properties in acute brain slices from Cx3cr1 knockout mice across postnatal hippocampal development. We found that fractalkine signaling is necessary for the development of several morphological and physiological features of microglia. Specifically, we found that the occurrence of an outward rectifying K+ current, typical of activated microglia, that peaked during the second and third postnatal week, was reduced in Cx3cr1 knockout mice. Fractalkine signaling also influenced microglial morphology and ability to extend processes in response to ATP following its focal application to the slice. Our results reveal the developmental profile of several morphological and physiological properties of microglia and demonstrate that these processes are modulated by fractalkine signaling.
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Affiliation(s)
- Francesca Pagani
- Center for Life Nanoscience - Istituto Italiano di Tecnologia@Sapienza, Rome Italy
| | - Rosa C Paolicelli
- Division of Psychiatry Research, University of Zürich, Zürich Switzerland ; Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo Italy
| | - Emanuele Murana
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy
| | - Barbara Cortese
- Consiglio Nazionale delle Ricerche - Institute of Inorganic Methodologies and Plasmas, Department of Physics, Sapienza University of Rome, Rome Italy
| | - Silvia Di Angelantonio
- Center for Life Nanoscience - Istituto Italiano di Tecnologia@Sapienza, Rome Italy ; Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy
| | - Emanuele Zurolo
- Department of Neuropathology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Eva Guiducci
- Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo Italy
| | - Tiago A Ferreira
- Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo Italy
| | - Stefano Garofalo
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy ; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed Pozzilli, Italy
| | - Giuseppina D'Alessandro
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy ; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed Pozzilli, Italy
| | - Alessandra Porzia
- Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome Rome, Italy
| | - Giovanna Peruzzi
- Center for Life Nanoscience - Istituto Italiano di Tecnologia@Sapienza, Rome Italy
| | - Fabrizio Mainiero
- Department of Experimental Medicine, Sapienza University of Rome Rome, Italy
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy ; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed Pozzilli, Italy
| | - Cornelius T Gross
- Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo Italy
| | - Davide Ragozzino
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome Italy ; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed Pozzilli, Italy
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28
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Michell-Robinson MA, Touil H, Healy LM, Owen DR, Durafourt BA, Bar-Or A, Antel JP, Moore CS. Roles of microglia in brain development, tissue maintenance and repair. Brain 2015; 138:1138-59. [PMID: 25823474 DOI: 10.1093/brain/awv066] [Citation(s) in RCA: 283] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 02/01/2015] [Indexed: 12/23/2022] Open
Abstract
The emerging roles of microglia are currently being investigated in the healthy and diseased brain with a growing interest in their diverse functions. In recent years, it has been demonstrated that microglia are not only immunocentric, but also neurobiological and can impact neural development and the maintenance of neuronal cell function in both healthy and pathological contexts. In the disease context, there is widespread consensus that microglia are dynamic cells with a potential to contribute to both central nervous system damage and repair. Indeed, a number of studies have found that microenvironmental conditions can selectively modify unique microglia phenotypes and functions. One novel mechanism that has garnered interest involves the regulation of microglial function by microRNAs, which has therapeutic implications such as enhancing microglia-mediated suppression of brain injury and promoting repair following inflammatory injury. Furthermore, recently published articles have identified molecular signatures of myeloid cells, suggesting that microglia are a distinct cell population compared to other cells of myeloid lineage that access the central nervous system under pathological conditions. Thus, new opportunities exist to help distinguish microglia in the brain and permit the study of their unique functions in health and disease.
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Affiliation(s)
- Mackenzie A Michell-Robinson
- 1 Neuroimmunology Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Hanane Touil
- 1 Neuroimmunology Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Luke M Healy
- 1 Neuroimmunology Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - David R Owen
- 2 Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Bryce A Durafourt
- 1 Neuroimmunology Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Amit Bar-Or
- 1 Neuroimmunology Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Jack P Antel
- 1 Neuroimmunology Unit, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Craig S Moore
- 3 Division of BioMedical Sciences, Faculty of Medicine, Memorial University, St. John's, Newfoundland, Canada
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Masia R, Krause DS, Yellen G. The inward rectifier potassium channel Kir2.1 is expressed in mouse neutrophils from bone marrow and liver. Am J Physiol Cell Physiol 2014; 308:C264-76. [PMID: 25472961 DOI: 10.1152/ajpcell.00176.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neutrophils are phagocytic cells that play a critical role in innate immunity by destroying bacterial pathogens. Channels belonging to the inward rectifier potassium channel subfamily 2 (Kir2 channels) have been described in other phagocytes (monocytes/macrophages and eosinophils) and in hematopoietic precursors of phagocytes. Their physiological function in these cells remains unclear, but some evidence suggests a role in growth factor-dependent proliferation and development. Expression of functional Kir2 channels has not been definitively demonstrated in mammalian neutrophils. Here, we show by RT-PCR that neutrophils from mouse bone marrow and liver express mRNA for the Kir2 subunit Kir2.1 but not for other subunits (Kir2.2, Kir2.3, and Kir2.4). In electrophysiological experiments, resting (unstimulated) neutrophils from mouse bone marrow and liver exhibit a constitutively active, external K(+)-dependent, strong inwardly rectifying current that constitutes the dominant current. The reversal potential is dependent on the external K(+) concentration in a Nernstian fashion, as expected for a K(+)-selective current. The current is not altered by changes in external or internal pH, and it is blocked by Ba(2+), Cs(+), and the Kir2-selective inhibitor ML133. The single-channel conductance is in agreement with previously reported values for Kir2.1 channels. These properties are characteristic of homomeric Kir2.1 channels. Current density in short-term cultures of bone marrow neutrophils is decreased in the absence of growth factors that are important for neutrophil proliferation [granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF)]. These results demonstrate that mouse neutrophils express functional Kir2.1 channels and suggest that these channels may be important for neutrophil function, possibly in a growth factor-dependent manner.
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Affiliation(s)
- Ricard Masia
- Department of Pathology and Laboratory Medicine, Massachusetts General Hospital, Boston, Massachusetts; and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
| | - Daniela S Krause
- Department of Pathology and Laboratory Medicine, Massachusetts General Hospital, Boston, Massachusetts; and
| | - Gary Yellen
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
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30
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Akita T, Okada Y. Characteristics and roles of the volume-sensitive outwardly rectifying (VSOR) anion channel in the central nervous system. Neuroscience 2014; 275:211-31. [DOI: 10.1016/j.neuroscience.2014.06.015] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/06/2014] [Accepted: 06/07/2014] [Indexed: 01/05/2023]
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31
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Siddiqui T, Lively S, Ferreira R, Wong R, Schlichter LC. Expression and contributions of TRPM7 and KCa2.3/SK3 channels to the increased migration and invasion of microglia in anti-inflammatory activation states. PLoS One 2014; 9:e106087. [PMID: 25148577 PMCID: PMC4141841 DOI: 10.1371/journal.pone.0106087] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 07/31/2014] [Indexed: 01/17/2023] Open
Abstract
Microglia rapidly respond to CNS injury and disease and can assume a spectrum of activation states. While changes in gene expression and production of inflammatory mediators have been extensively described after classical (LPS-induced) and alternative (IL4-induced) microglial activation, less is known about acquired de-activation in response to IL10. It is important to understand how microglial activation states affect their migration and invasion; crucial functions after injury and in the developing CNS. We reported that LPS-treated rat microglia migrate very poorly, while IL4-treated cells migrate and invade much better. Having discovered that the lamellum of migrating microglia contains a large ring of podosomes – microscopic structures that are thought to mediate adhesion, migration and invasion – we hypothesized that IL4 and IL10 would differentially affect podosome expression, gene induction, migration and invasion. Further, based on the enrichment of the KCa2.3/SK3 Ca2+-activated potassium channel in microglial podosomes, we predicted that it regulates migration and invasion. We found both similarities and differences in gene induction by IL4 and IL10 and, while both cytokines increased migration and invasion, only IL10 affected podosome expression. KCa2.3 currents were recorded in microglia under all three activation conditions and KCNN3 (KCa2.3) expression was similar. Surprisingly then, of three KCa2.3 inhibitors (apamin, tamapin, NS8593), only NS8593 abrogated the increased migration and invasion of IL4 and IL10-treated microglia (and invasion of unstimulated microglia). This discrepancy was explained by the observed block of TRPM7 currents in microglia by NS8593, which occurred under all three activation conditions. A similar inhibition of both migration and invasion was seen with a TRPM7 inhibitor (AA-861) that does not block KCa2.3 channels. Thus, we conclude that TRPM7 (not KCa2.3) contributes to the enhanced ability of microglia to migrate and invade when in anti-inflammatory states. This will be an important consideration in developing TRPM7 inhibitors for treating CNS injury.
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Affiliation(s)
- Tamjeed Siddiqui
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Starlee Lively
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
| | - Roger Ferreira
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Raymond Wong
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Lyanne C. Schlichter
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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32
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Ferreira R, Lively S, Schlichter LC. IL-4 type 1 receptor signaling up-regulates KCNN4 expression, and increases the KCa3.1 current and its contribution to migration of alternative-activated microglia. Front Cell Neurosci 2014; 8:183. [PMID: 25071444 PMCID: PMC4077126 DOI: 10.3389/fncel.2014.00183] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/14/2014] [Indexed: 01/05/2023] Open
Abstract
The Ca2+-activated K+ channel, KCa3.1 (KCNN4/IK1/SK4), contributes to “classical,” pro-inflammatory activation of microglia, and KCa3.1 blockers have improved the outcome in several rodent models of CNS damage. For instance, blocking KCa3.1 with TRAM-34 rescued retinal ganglion neurons after optic nerve damage in vivo and, reduced p38 MAP kinase activation, production of reactive oxygen and nitrogen species, and neurotoxicity by microglia in vitro. In pursuing the therapeutic potential of KCa3.1 blockers, it is crucial to assess KCa3.1 contributions to other microglial functions and activation states, especially the IL-4-induced “alternative” activation state that can counteract pro-inflammatory states. We recently found that IL-4 increases microglia migration – a crucial function in the healthy and damaged CNS – and that KCa3.1 contributes to P2Y2 receptor-stimulated migration. Here, we discovered that KCa3.1 is greatly increased in alternative-activated rat microglia and then contributes to an enhanced migratory capacity. IL-4 up-regulated KCNN4 mRNA (by 6 h) and greatly increased the KCa3.1 current by 1 day, and this required de novo protein synthesis. The increase in current was sustained for at least 6 days. IL-4 increased microglial migration and this was reversed by blocking KCa3.1 with TRAM-34. A panel of inhibitors of signal-transduction mediators was used to analyze contributions of IL-4-related signaling pathways. Induction of KCNN4 mRNA and KCa3.1 current was mediated specifically through IL-4 binding to the type I receptor and, surprisingly, it required JAK3, Ras/MEK/ERK signaling and the transcription factor, activator protein-1, rather than JAK2, STAT6, or phosphatidylinositol 3-kinase.The same receptor subtype and pathway were required for the enhanced KCa3.1-dependent migration. In providing the first direct signaling link between an IL-4 receptor, expression and roles of an ion channel, this study also highlights the potential importance of KCa3.1 in alternative-activated microglia.
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Affiliation(s)
- Roger Ferreira
- Genes and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Physiology, University of Toronto Toronto, ON, Canada
| | - Starlee Lively
- Genes and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada
| | - Lyanne C Schlichter
- Genes and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Physiology, University of Toronto Toronto, ON, Canada
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33
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Ferreira R, Schlichter LC. Selective activation of KCa3.1 and CRAC channels by P2Y2 receptors promotes Ca(2+) signaling, store refilling and migration of rat microglial cells. PLoS One 2013; 8:e62345. [PMID: 23620825 PMCID: PMC3631179 DOI: 10.1371/journal.pone.0062345] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/20/2013] [Indexed: 12/26/2022] Open
Abstract
Microglial activation involves Ca(2+) signaling, and numerous receptors can evoke elevation of intracellular Ca(2+). ATP released from damaged brain cells can activate ionotropic and metabotropic purinergic receptors, and act as a chemoattractant for microglia. Metabotropic P2Y receptors evoke a Ca(2+) rise through release from intracellular Ca(2+) stores and store-operated Ca(2+) entry, and some have been implicated in microglial migration. This Ca(2+) rise is expected to activate small-conductance Ca(2+)-dependent K(+) (SK) channels, if present. We previously found that SK3 (KCa2.3) and KCa3.1 (SK4/IK1) are expressed in rat microglia and contribute to LPS-mediated activation and neurotoxicity. However, neither current has been studied by elevating Ca(2+) during whole-cell recordings. We hypothesized that, rather than responding only to Ca(2+), each channel type might be coupled to different receptor-mediated pathways. Here, our objective was to determine whether the channels are differentially activated by P2Y receptors, and, if so, whether they play differing roles. We used primary rat microglia and a rat microglial cell line (MLS-9) in which riluzole robustly activates both SK3 and KCa3.1 currents. Using electrophysiological, Ca(2+) imaging and pharmacological approaches, we show selective functional coupling of KCa3.1 to UTP-mediated P2Y2 receptor activation. KCa3.1 current is activated by Ca(2+) entry through Ca(2+)-release-activated Ca(2+) (CRAC/Orai1) channels, and both CRAC/Orai1 and KCa3.1 channels facilitate refilling of Ca(2+) stores. The Ca(2+) dependence of KCa3.1 channel activation was skewed to abnormally high concentrations, and we present evidence for a close physical association of the two channel types. Finally, migration of primary rat microglia was stimulated by UTP and inhibited by blocking either KCa3.1 or CRAC/Orai1 channels. This is the first report of selective coupling of one type of SK channel to purinergic stimulation of microglia, transactivation of KCa3.1 channels by CRAC/Orai1, and coordinated roles for both channels in store refilling, Ca(2+) signaling and microglial migration.
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Affiliation(s)
- Roger Ferreira
- Genes and Development Division, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Lyanne C. Schlichter
- Genes and Development Division, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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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
Abstract
Microglia are a special type of supporting cells in the nervous system. between the functions they perform are myelin production, structural support, regulation of extracellular fluid, glial scar formation among others. This cell type for its versatility, is also related to pathological events, where his multiple roles and the release of proinflammatory factors can contribute to understand especially in traumatic brain injury, as secondary injury and the healing process, important aspects the context of brain injury.
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Ashraf T, Kis O, Banerjee N, Bendayan R. Drug Transporters At Brain Barriers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013. [DOI: 10.1007/978-1-4614-4711-5_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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37
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He S, Shao LR, Rittase WB, Bausch SB. Increased Kv1 channel expression may contribute to decreased sIPSC frequency following chronic inhibition of NR2B-containing NMDAR. Neuropsychopharmacology 2012; 37:1338-56. [PMID: 22218089 PMCID: PMC3327840 DOI: 10.1038/npp.2011.320] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 10/21/2011] [Accepted: 11/29/2011] [Indexed: 12/20/2022]
Abstract
Numerous studies have documented the effects of chronic N-methyl-D-aspartate receptor (NMDAR) blockade on excitatory circuits, but the effects on inhibitory circuitry are not well studied. NR2A- and NR2B-containing NMDARs play differential roles in physiological processes, but the consequences of chronic NR2A- or NR2B-containing NMDAR inhibition on glutamatergic and GABAergic neurotransmission are unknown. We investigated altered GABAergic neurotransmission in dentate granule cells and interneurons following chronic treatment with the NR2B-selective antagonist, Ro25,6981, the NR2A-prefering antagonist, NVP-AAM077, or the non-subunit-selective NMDAR antagonist, D-APV, in organotypic hippocampal slice cultures. Electrophysiological recordings revealed large reductions in spontaneous inhibitory postsynaptic current (sIPSC) frequency in both granule cells and interneurons following chronic Ro25,6981 treatment, which was associated with minimally altered sIPSC amplitude, miniature inhibitory postsynaptic current (mIPSC) frequency, and mIPSC amplitude, suggesting diminished action potential-dependent GABA release. Chronic NVP-AAM077 or D-APV treatment had little effect on these measures. Reduced sIPSC frequency did not arise from downregulated GABA(A)R, altered excitatory or inhibitory drive to interneurons, altered interneuron membrane properties, increased failure rate, decreased action potential-dependent release probability, or mGluR/GABA(B) receptor modulation of GABA release. However, chronic Ro25,6981-mediated reductions in sIPSC frequency were occluded by the K+ channel blockers, dendrotoxin, margatoxin, and agitoxin, but not dendrotoxin-K or XE991. Immunohistochemistry also showed increased Kv1.2, Kv1.3, and Kv1.6 in the dentate molecular layer following chronic Ro25,6981 treatment. Our findings suggest that increased Kv1 channel expression/function contributed to diminished action potential-dependent GABA release following chronic NR2B-containing NMDAR inhibition and that these Kv1 channels may be heteromeric complexes containing Kv1.2, Kv1.3, and Kv1.6.
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Affiliation(s)
- Shuijin He
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
- Graduate Program in Neuroscience, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - Li-Rong Shao
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - W Bradley Rittase
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - Suzanne B Bausch
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
- Graduate Program in Neuroscience, Uniformed Services University School of Medicine, Bethesda, MD, USA
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Nikouee A, Khabiri M, Grissmer S, Ettrich R. Charybdotoxin and margatoxin acting on the human voltage-gated potassium channel hKv1.3 and its H399N mutant: an experimental and computational comparison. J Phys Chem B 2012; 116:5132-40. [PMID: 22490327 DOI: 10.1021/jp2102463] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The effect of the pore-blocking peptides charybdotoxin and margatoxin, both scorpion toxins, on currents through human voltage-gated hK(v)1.3 wild-type and hK(v)1.3_H399N mutant potassium channels was characterized by the whole-cell patch clamp technique. In the mutant channels, both toxins hardly blocked current through the channels, although they did prevent C-type inactivation by slowing down the current decay during depolarization. Molecular dynamics simulations suggested that the fast current decay in the mutant channel was a consequence of amino acid reorientations behind the selectivity filter and indicated that the rigidity-flexibility in that region played a key role in its interactions with scorpion toxins. A channel with a slightly more flexible selectivity filter region exhibits distinct interactions with scorpion toxins. Our studies suggest that the toxin-channel interactions might partially restore rigidity in the selectivity filter and thereby prevent the structural rearrangements associated with C-type inactivation.
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Affiliation(s)
- Azadeh Nikouee
- Institute of Applied Physiology, Ulm University, Ulm, Germany
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Liu BS, Ferreira R, Lively S, Schlichter LC. Microglial SK3 and SK4 currents and activation state are modulated by the neuroprotective drug, riluzole. J Neuroimmune Pharmacol 2012; 8:227-37. [PMID: 22527636 DOI: 10.1007/s11481-012-9365-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 03/28/2012] [Indexed: 12/21/2022]
Abstract
Microglia monitor the CNS for 'danger' signals after acute injury, such as stroke and trauma, and then undergo complex activation processes. Classical activation of microglia can produce neurotoxic levels of glutamate and immune mediators (e.g., pro-inflammatory cytokines, reactive oxygen and nitrogen species), while alternative activation up-regulates anti-inflammatory molecules and is thought to resolve inflammation and protect the brain. Thus, pharmacological strategies to decrease classical- and/or promote alternative activation are of interest. Here, we assessed actions of the neuroprotective drug, riluzole, on two Ca(2+)- activated K channels in microglia - SK3 (KCa2.3, KCNN3) and SK4 (KCa3.1, KCNN4) - and on classical versus alternative microglial activation. Riluzole is used to treat amyotrophic lateral sclerosis, and is in clinical trials for several other CNS disorders, where it has been presumed to target neurons and reduce glutamate-mediated toxicity. We show that simply elevating intracellular Ca(2+) to micromolar levels in whole-cell recordings does not activate SK channels in a cell line derived from primary rat microglia (MLS-9). In intact cells, riluzole raised cytoplasmic Ca(2+), but it was marginal (~200 nM) and transient (2 min). Surprisingly then, in whole cell recordings, riluzole rapidly activated SK3 and SK4 channels for as long as it was present, and did not require elevated intracellular Ca(2+). We then used primary rat microglia to analyze expression of several activation markers and inflammatory mediators. Riluzole decreased classical LPS-induced activation, and increased some aspects of IL-4-induced alternative activation. These actions on microglia suggest an additional mechanism underlying the neuroprotective actions of riluzole.
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Affiliation(s)
- B-S Liu
- Toronto Western Research Institute, University Health Network, MC9-417, 399 Bathurst Street, Toronto, Ontario M5T 2S8, Canada
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40
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Swayne LA, Wicki-Stordeur L. Ion channels in postnatal neurogenesis: potential targets for brain repair. Channels (Austin) 2012; 6:69-74. [PMID: 22614818 DOI: 10.4161/chan.19721] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Neural stem and progenitor cells (NSC/NPCs) are unspecialized cells found in the adult peri-ventricular and sub-granular zones that are capable of self-renewal, migration, and differentiation into new neurons through the remarkable process of postnatal neurogenesis. We are now beginning to understand that the concerted action of ion channels, multi-pass transmembrane proteins that allow passage of ions across otherwise impermeable cellular membranes tightly regulate this process. Specific ion channels control proliferation, differentiation and survival. Furthermore, they have the potential to be highly selective drug targets due to their complex structures. As such, these proteins represent intriguing prospects for control and optimization of postnatal neurogenesis for neural regeneration following brain injury or disease. Here, we concentrate on ion channels identified in adult ventricular zone NSC/NPCs that have been found to influence the stages of neurogenesis. Finally, we outline the potential of these channels to elicit repair, and highlight the outstanding challenges.
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Affiliation(s)
- Leigh Anne Swayne
- Division of Medical Sciences; Island Medical Program, University of Victoria, Victoria, BC, Canada.
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41
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Differential expression and roles of volume-activated chloride channels in control of growth of normal and cancerous nasopharyngeal epithelial cells. Biochem Pharmacol 2012; 83:324-34. [DOI: 10.1016/j.bcp.2011.11.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 10/29/2011] [Accepted: 11/08/2011] [Indexed: 11/16/2022]
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42
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Lam J, Wulff H. The Lymphocyte Potassium Channels Kv1.3 and KCa3.1 as Targets for Immunosuppression. Drug Dev Res 2011; 72:573-584. [PMID: 22241939 PMCID: PMC3253536 DOI: 10.1002/ddr.20467] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The voltage-gated Kv1.3 and the calcium-activated KCa3.1 potassium channel modulate many calcium-dependent cellular processes in immune cells, including T-cell activation and proliferation, and have therefore been proposed as novel therapeutic targets for immunomodulation. Kv1.3 is highly expressed in CCR7(-) effector memory T cells and is emerging as a target for T-cell mediated diseases like multiple sclerosis, rheumatoid arthritis, type-1 diabetes mellitus, allergic contact dermatitis, and psoriasis. KCa3.1 in contrast is expressed in CCR7(+) naïve and central memory T cells, as well as in mast cells, macrophages, dedifferentiated vascular smooth muscle cells, fibroblasts, vascular endothelium, and airway epithelium. Given this expression pattern, KCa3.1 is a potential therapeutic target for conditions ranging from inflammatory bowel disease, multiple sclerosis, arthritis, and asthma to cardiovascular diseases like atherosclerosis and post-angioplasty restenosis. Results from animal studies have been supportive of the therapeutic potential of both Kv1.3 and KCa3.1 blockers and have also not shown any toxicities associated with pharmacological Kv1.3 and KCa3.1 blockade. To date, two compounds targeting Kv1.3 are in preclinical development but, so far, no Kv1.3 blocker has advanced into clinical trials. KCa3.1 blockers, on the other hand, have been evaluated in clinical trials for sickle cell anemia and exercise-induced asthma, but have so far not shown efficacy. However, the trial results support KCa3.1 as a safe therapeutic target, and will hopefully help enable clinical trials for other medical conditions that might benefit from KCa3.1 blockade.
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Affiliation(s)
- Jenny Lam
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
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43
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Abstract
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
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44
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Schlichter LC, Mertens T, Liu B. Swelling activated Cl- channels in microglia: Biophysics, pharmacology and role in glutamate release. Channels (Austin) 2011; 5:128-37. [PMID: 21150294 DOI: 10.4161/chan.5.2.14310] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Microglia have a swelling-activated Cl- current (which we call IClswell), and while some of its biophysical properties and functional roles have been elucidated, its molecular identity is unknown. To relate this current to cell functions and determine whether it is regulated by mechanisms other than cell swelling, it is important to establish both biophysical and pharmacological fingerprints. Here, we used rat microglia and a cell line derived from them (MLS-9) to study biophysical, regulatory and pharmacological properties of IClswell. The whole-cell current was activated in response to a hypo-osmotic bath solution, but not by voltage, and was time-independent during long voltage steps. The halide selectivity sequence was I->Br->Cl- (Eisenman sequence I) and importantly, the excitatory amino acid, glutamate was permeant. Current activation required internal ATP, and was not affected by the guanine nucleotides, GTPS or GDPS, or physiological levels of internal Mg2+. The same current was activated by a low intracellular ionic strength solution without an osmotic gradient. IClswell was reversibly inhibited by known Cl- channel blockers (NPPB, flufenamic acid, glibenclamide, DCPIB), and by the glutamate release inhibitor, riluzole. Cell swelling evoked glutamate release from primary microglia and MLS-9 cells, and this was inhibited by the blockers (above), and by IAA-94, but not by tamoxifen or the Na+/K+/Cl- symport inhibitor, bumetanide. Together, these results confirm the similarity of IClswell in the two cell types, and point to a role for this channel in inflammation-mediated glutamate release in the CNS.
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Affiliation(s)
- Lyanne C Schlichter
- Toronto Western Research Institute, University Health Network, Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
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Wulff H. Spiro azepane-oxazolidinones as Kv1.3 potassium channel blockers: WO2010066840. Expert Opin Ther Pat 2010; 20:1759-65. [PMID: 20954790 DOI: 10.1517/13543776.2010.528392] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This article evaluates a patent application from Solvay Pharmaceuticals, which claims spiro azepane-oxazolidinones as novel blockers of the voltage-gated potassium channel Kv1.3 for the treatment of diabetes, psoriasis, obesity, transplant rejection and T-cell mediated autoimmune diseases such as rheumatoid arthritis and MS. The patent describes a new chemotype of Kv1.3 blockers and thus illustrates the growing interest of the pharmaceutical industry in Kv1.3 as a target of immunosuppression and metabolic disorders. This article briefly summarizes the chemistry and biological data provided in the patent and then compares the new compounds to Kv1.3 blockers previously disclosed by both academia and pharmaceutical companies.
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Affiliation(s)
- Heike Wulff
- University of California, Department of Pharmacology, Davis, Davis, CA 95616, USA.
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46
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Tian M, Duan Y, Duan X. Chloride channels regulate chondrogenesis in chicken mandibular mesenchymal cells. Arch Oral Biol 2010; 55:938-45. [PMID: 20832772 DOI: 10.1016/j.archoralbio.2010.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 08/04/2010] [Accepted: 08/16/2010] [Indexed: 12/21/2022]
Abstract
Voltage gated chloride channels (ClCs) play an important role in the regulation of intracellular pH and cell volume homeostasis. Mutations of these genes result in genetic diseases with abnormal bone deformation and body size, indicating that ClCs may have a role in chondrogenesis. In the present study, we isolated chicken mandibular mesenchymal cells (CMMC) from Hamburg-Hamilton (HH) stage 26 chick embryos and induced chondrocyte maturation by using ascorbic acid and β-glycerophosphate (AA-BGP). We also determined the effect of the chloride channel inhibitor NPPB [5-nitro-2-(3-phenylpropylamino) benzoic acid] on regulation of growth, differentiation, and gene expression in these cells using MTT and real-time PCR assays. We found that CLCN1 and CLCN3-7 mRNA were expressed in CMMC and NPPB reduced expression of CLCN3, CLCN5, and CLCN7 mRNA in these cells. At the same time, NPPB inhibited the growth of the CMMC, but had no effect on the mRNA level of cyclin D1 and cyclin E (P>0.05) with/without AA-BGP treatment. AA-BGP increased markers for early chondrocyte differentiation including type II collagen, aggrecan (P<0.01) and Sox9 (P<0.05), whilst had no effect on the late chondrocyte differentiation marker type X collagen. NPPB antagonized AA-BGP-induced expression of type II collagen and aggrecan (P<0.05). Furthermore, NPPB downregulated type X collagen (P<0.05) with/without AA-BGP treatment. We conclude that abundant chloride channel genes in CMMC play important roles in regulating chondrocyte proliferation and differentiation. Type X collagen might function as a target of chloride channel inhibitors during the differentiation process.
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Affiliation(s)
- Meiyu Tian
- Department of Orthodontics, School of Stomatology, The Fourth Military Medical University, 145 Changle West Road, Xi'an, Shaanxi 710032, PR China
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Eder C. Ion channels in monocytes and microglia / brain macrophages: Promising therapeutic targets for neurological diseases. J Neuroimmunol 2010; 224:51-5. [DOI: 10.1016/j.jneuroim.2010.05.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 05/04/2010] [Indexed: 10/19/2022]
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48
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Regulation of proteins mediating neurodegeneration in experimental autoimmune encephalomyelitis and multiple sclerosis. Proteomics Clin Appl 2009; 3:1273-87. [DOI: 10.1002/prca.200800155] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 05/13/2009] [Accepted: 07/19/2009] [Indexed: 12/28/2022]
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49
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Kjaer K, Strøbaek D, Christophersen P, Rønn LCB. Chloride channel blockers inhibit iNOS expression and NO production in IFNgamma-stimulated microglial BV2 cells. Brain Res 2009; 1281:15-24. [PMID: 19446535 DOI: 10.1016/j.brainres.2009.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 03/13/2009] [Accepted: 05/02/2009] [Indexed: 01/25/2023]
Abstract
Microglial cells play an important role during neuroinflammation in the central nervous system. Among other factors, activated microglia produce nitric oxide (NO), which is toxic to neurons and excessive microglial activation and NO production contribute to the pathology of neurodegenerative diseases. Chloride channels have previously been shown to participate in microglial activation. Here we investigate the effects of established chloride channel blockers with different chemical structures on interferon-gamma (IFNgamma)-induced activation of the murine microglial cell line, BV2. IFNgamma-induced NO production was effectively reduced by NPPB, IAA-94, tamoxifen, NS3728 and NS1652, with NS1652 being the most potent. In contrast, DIDS reduced NO production only at cytotoxic concentrations. Furthermore, NS1652 reduced the protein and mRNA levels of inducible nitric oxide synthase (iNOS), without altering STAT1 phosphorylation. These observations suggest a microglial chloride conductance as a critical permissive factor downstream in the IFNgamma-induced iNOS cascade. The nature of the underlying channel is unknown, but the pharmacological profile appears incompatible with the involvement of the volume activated anion conductance (VRAC).
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Affiliation(s)
- Katrine Kjaer
- NeuroSearch A/S, Pederstrupvej 93, Ballerup, Denmark
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50
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Wu CY, Kaur C, Sivakumar V, Lu J, Ling EA. Kv1.1 expression in microglia regulates production and release of proinflammatory cytokines, endothelins and nitric oxide. Neuroscience 2009; 158:1500-8. [DOI: 10.1016/j.neuroscience.2008.11.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 11/24/2008] [Accepted: 11/25/2008] [Indexed: 01/14/2023]
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