1
|
Tourkova IL, Larrouture QC, Liu S, Luo J, Shipman KE, Onwuka KM, Weisz OA, Riazanski V, Nelson DJ, MacDonald ML, Schlesinger PH, Blair HC. Chloride/proton antiporters ClC3 and ClC5 support bone formation in mice. Bone Rep 2024; 21:101763. [PMID: 38666049 PMCID: PMC11043850 DOI: 10.1016/j.bonr.2024.101763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Acid transport is required for bone synthesis by osteoblasts. The osteoblast basolateral surface extrudes acid by Na+/H+ exchange, but apical proton uptake is undefined. We found high expression of the Cl-/H+ exchanger ClC3 at the bone apical surface. In mammals ClC3 functions in intracellular vesicular chloride transport, but when we found Cl- dependency of H+ transport in osteoblast membranes, we queried whether ClC3 Cl-/H+ exchange functions in bone formation. We used ClC3 knockout animals, and closely-related ClC5 knockout animals: In vitro studies suggested that both ClC3 and ClC5 might support bone formation. Genotypes were confirmed by total exon sequences. Expression of ClC3, and to a lesser extent of ClC5, at osteoblast apical membranes was demonstrated by fluorescent antibody labeling and electron microscopy with nanometer gold labeling. Animals with ClC3 or ClC5 knockouts were viable. In ClC3 or ClC5 knockouts, bone formation decreased ~40 % by calcein and xylenol orange labeling in vivo. In very sensitive micro-computed tomography, ClC5 knockout reduced bone relative to wild type, consistent with effects of ClC3 knockout, but varied with specific histological parameters. Regrettably, ClC5-ClC3 double knockouts are not viable, suggesting that ClC3 or ClC5 activity are essential to life. We conclude that ClC3 has a direct role in bone formation with overlapping but probably slightly smaller effects of ClC5. The mechanism in mineral formation might include ClC H+ uptake, in contrast to ClC3 and ClC5 function in cell vesicles or other organs.
Collapse
Affiliation(s)
- Irina L. Tourkova
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
- Research Service, VA Healthcare System, Pittsburgh, PA, USA
| | | | - Silvia Liu
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jianhua Luo
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Katherine E. Shipman
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kelechi M. Onwuka
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ora A. Weisz
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Vladimir Riazanski
- Dept of Neurobiology, Pharmacology & Physiology, University of Chicago, Chicago, IL, USA
| | - Deborah J. Nelson
- Dept of Neurobiology, Pharmacology & Physiology, University of Chicago, Chicago, IL, USA
| | - Matthew L. MacDonald
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | - Harry C. Blair
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
- Research Service, VA Healthcare System, Pittsburgh, PA, USA
| |
Collapse
|
2
|
Jimenez C, Hawn MB, Akin E, Leblanc N. Translational potential of targeting Anoctamin-1-Encoded Calcium-Activated chloride channels in hypertension. Biochem Pharmacol 2022; 206:115320. [PMID: 36279919 DOI: 10.1016/j.bcp.2022.115320] [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: 08/24/2022] [Revised: 10/13/2022] [Accepted: 10/17/2022] [Indexed: 12/14/2022]
Abstract
Calcium-activated chloride channels (CaCC) provide a depolarizing stimulus to a variety of tissues through chloride efflux in response to a rise in internal Ca2+ and voltage. One of these channels, Anoctamin-1 (ANO1 or TMEM16A) is now recognized to play a central role in promoting smooth muscle tone in various types of blood vessels. Its role in hypertension, and thus the therapeutic promise of targeting ANO1, is less straightforward. This review gives an overview of our current knowledge about the potential role ANO1 may play in hypertension within the systemic, portal, and pulmonary vascular systems and the importance of this information when pursuing potential treatment strategies. While the role of ANO1 is well-established in several forms of pulmonary hypertension, its contributions to both the generation of vascular tone and its role in hypertension within the systemic and portal systems are much less clear. This, combined with ANO1's various roles throughout a multitude of tissues throughout the body, command caution when targeting ANO1 as a therapeutic target and may require tissue-selective strategies.
Collapse
Affiliation(s)
- Connor Jimenez
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Matthew B Hawn
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Elizabeth Akin
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Normand Leblanc
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA.
| |
Collapse
|
3
|
Hawn MB, Akin E, Hartzell H, Greenwood IA, Leblanc N. Molecular mechanisms of activation and regulation of ANO1-Encoded Ca 2+-Activated Cl - channels. Channels (Austin) 2021; 15:569-603. [PMID: 34488544 PMCID: PMC8480199 DOI: 10.1080/19336950.2021.1975411] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 08/29/2021] [Indexed: 01/13/2023] Open
Abstract
Ca2+-activated Cl- channels (CaCCs) perform a multitude of functions including the control of cell excitability, regulation of cell volume and ionic homeostasis, exocrine and endocrine secretion, fertilization, amplification of olfactory sensory function, and control of smooth muscle cell contractility. CaCCs are the translated products of two members (ANO1 and ANO2, also known as TMEM16A and TMEM16B) of the Anoctamin family of genes comprising ten paralogs. This review focuses on recent progress in understanding the molecular mechanisms involved in the regulation of ANO1 by cytoplasmic Ca2+, post-translational modifications, and how the channel protein interacts with membrane lipids and protein partners. After first reviewing the basic properties of native CaCCs, we then present a brief historical perspective highlighting controversies about their molecular identity in native cells. This is followed by a summary of the fundamental biophysical and structural properties of ANO1. We specifically address whether the channel is directly activated by internal Ca2+ or indirectly through the intervention of the Ca2+-binding protein Calmodulin (CaM), and the structural domains responsible for Ca2+- and voltage-dependent gating. We then review the regulation of ANO1 by internal ATP, Calmodulin-dependent protein kinase II-(CaMKII)-mediated phosphorylation and phosphatase activity, membrane lipids such as the phospholipid phosphatidyl-(4,5)-bisphosphate (PIP2), free fatty acids and cholesterol, and the cytoskeleton. The article ends with a survey of physical and functional interactions of ANO1 with other membrane proteins such as CLCA1/2, inositol trisphosphate and ryanodine receptors in the endoplasmic reticulum, several members of the TRP channel family, and the ancillary Κ+ channel β subunits KCNE1/5.
Collapse
Affiliation(s)
- M. B. Hawn
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - E. Akin
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - H.C. Hartzell
- Department of Cell Biology, Emory University School of Medicine, USA
| | - I. A. Greenwood
- Department of Vascular Pharmacology, St. George’s University of London, UK
| | - N. Leblanc
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| |
Collapse
|
4
|
Abstract
Chloride channel 3 (ClC-3), a Cl-/H+ antiporter, has been well established as a member of volume-regulated chloride channels (VRCCs). ClC-3 may be a crucial mediator for activating inflammation-associated signaling pathways by regulating protein phosphorylation. A growing number of studies have indicated that ClC-3 overexpression plays a crucial role in mediating increased plasma low-density lipoprotein levels, vascular endothelium dysfunction, pro-inflammatory activation of macrophages, hyper-proliferation and hyper-migration of vascular smooth muscle cells (VSMCs), as well as oxidative stress and foam cell formation, which are the main factors responsible for atherosclerotic plaque formation in the arterial wall. In the present review, we summarize the molecular structures and classical functions of ClC-3. We further discuss its emerging role in the atherosclerotic process. In conclusion, we explore the potential role of ClC-3 as a therapeutic target for atherosclerosis.
Collapse
Affiliation(s)
- Dun Niu
- Institute of Pharmacy and Pharmacology, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, 34706University of South China, Hengyang, China
| | - Lanfang Li
- Institute of Pharmacy and Pharmacology, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, 34706University of South China, Hengyang, China
| | - Zhizhong Xie
- Institute of Pharmacy and Pharmacology, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, 34706University of South China, Hengyang, China
| |
Collapse
|
5
|
Schlesinger PH, Blair HC, Beer Stolz D, Riazanski V, Ray EC, Tourkova IL, Nelson DJ. Cellular and extracellular matrix of bone, with principles of synthesis and dependency of mineral deposition on cell membrane transport. Am J Physiol Cell Physiol 2019; 318:C111-C124. [PMID: 31532718 DOI: 10.1152/ajpcell.00120.2019] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Bone differs from other connective tissues; it is isolated by a layer of osteoblasts that are connected by tight and gap junctions. This allows bone to create dense lamellar type I collagen, control pH, mineral deposition, and regulate water content forming a compact and strong structure. New woven bone formed after degradation of mineralized cartilage is rapidly degraded and resynthesized to impart structural order for local bone strength. Ossification is regulated by thickness of bone units and by patterning via bone morphogenetic receptors including activin, other bone morphogenetic protein receptors, transforming growth factor-β receptors, all part of a receptor superfamily. This superfamily interacts with receptors for additional signals in bone differentiation. Important features of the osteoblast environment were established using recent tools including osteoblast differentiation in vitro. Osteoblasts deposit matrix protein, over 90% type I collagen, in lamellae with orientation alternating parallel or orthogonal to the main stress axis of the bone. Into this organic matrix, mineral is deposited as hydroxyapatite. Mineral matrix matures from amorphous to crystalline hydroxyapatite. This process includes at least two-phase changes of the calcium-phosphate mineral as well as intermediates involving tropocollagen fibrils to form the bone composite. Beginning with initiation of mineral deposition, there is uncertainty regarding cardinal processes, but the driving force is not merely exceeding the calcium-phosphate solubility product. It occurs behind a epithelial-like layer of osteoblasts, which generate phosphate and remove protons liberated during calcium-phosphate salt deposition. The forming bone matrix is discontinuous from the general extracellular fluid. Required adjustment of ionic concentrations and water removal from bone matrix are important details remaining to be addressed.
Collapse
Affiliation(s)
| | - Harry C Blair
- Veterans Affairs Medical Center, Pittsburgh, Pennsylvania.,Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Donna Beer Stolz
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Vladimir Riazanski
- Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, Illinois
| | - Evan C Ray
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Irina L Tourkova
- Veterans Affairs Medical Center, Pittsburgh, Pennsylvania.,Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Deborah J Nelson
- Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, Illinois
| |
Collapse
|
6
|
Starvation-induced autophagy is up-regulated via ROS-mediated ClC-3 chloride channel activation in the nasopharyngeal carcinoma cell line CNE-2Z. Biochem J 2019; 476:1323-1333. [DOI: 10.1042/bcj20180979] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 04/13/2019] [Accepted: 04/16/2019] [Indexed: 01/15/2023]
Abstract
Abstract
Nutrient deficiency develops frequently in nasopharyngeal carcinoma cell (CNE-2Z) due to the characteristics of aggregation and uncontrolled proliferation. Therefore, starvation can induce autophagy in these cells. Chloride channel 3 (ClC-3), a member of the chloride channel family, is involved in various biological processes. However, whether ClC-3 plays an important role in starvation-induced autophagy is unclear. In this study, Earle's balanced salt solution (EBSS) was used to induce autophagy in CNE-2Z cells. We found that autophagy and the chloride current induced by EBSS were inhibited by chloride channel blockers. ClC-3 knockdown inhibited the degradation of LC3-II and P62. Furthermore, when reactive oxygen species (ROS) generation was suppressed by antioxidant N-acetyl-l-cysteine (L-NAC) pretreatment, EBSS-induced autophagy was inhibited, and the chloride current was unable to be activated. Nevertheless, ClC-3 knockdown had little effect on ROS levels, indicating that ROS acted upstream of ClC-3 and that both ROS and ClC-3 participated in EBSS-induced autophagy regulation in CNE-2Z.
Collapse
|
7
|
Cheng W, Zheng S, Li L, Zhou Q, Zhu H, Hu J, Luo H. Chloride channel 3 (CIC-3) predicts the tumor size in hepatocarcinoma. Acta Histochem 2019; 121:284-288. [PMID: 30678806 DOI: 10.1016/j.acthis.2019.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 01/17/2019] [Accepted: 01/17/2019] [Indexed: 02/02/2023]
Abstract
Chloride channel 3 (CIC-3) has been suggested to be implicated in the carcinogenesis though; it still remains ill understood in hepatocarcinoma, especially in terms of clinicopathological meaning of its expression. Given this, herein, to understand the clinicopathological significance of CIC-3 expression in hepatocarcinoma, Immunohistochemistry was performed to examine the level of CIC-3, followed by statistical analysis of the correlation between expression versus clinicopathological variables, including gender, age, TNM classifications, tumor size, lymph node metastasis and overall prognosis. It was shown that positive staining of CIC-3 can be present in both hepatocarcinoma and its paired normal controls; and that CIC-3 was significantly over-expressed in hepatcarcioma on the whole relative to paired normal controls. Moreover, up-regulation of CIC-3 markedly correlated with tumor size and overall prognosis, suggesting that CIC-3 expression could predict both tumor size and overall prognosis in hepatocarcinoma.
Collapse
Affiliation(s)
- Wei Cheng
- Department of Hematologic and Oncology, The Center Hospital of Karamay City, Karamay, 834000, Xinjiang, China
| | - Shutao Zheng
- State Key Laboratory of Pathogenesis, Prevention, Treatment of Central Asian High Incidence Diseases, Xinjiang Uygur Autonomous Region, Urumqi, 830011, China; Clinical Medical Research Institute, First Affiliated Hospital of Xinjiang Medical University, Xinjiang Uygur Autonomous Region, Urumqi, 830011, China
| | - Li Li
- Department of Hematologic and Oncology, The Center Hospital of Karamay City, Karamay, 834000, Xinjiang, China
| | - Qin Zhou
- Department of Hematologic and Oncology, The Center Hospital of Karamay City, Karamay, 834000, Xinjiang, China
| | - Haipeng Zhu
- Department of Hematologic and Oncology, The Center Hospital of Karamay City, Karamay, 834000, Xinjiang, China
| | - Jun Hu
- Department of Hematologic and Oncology, The Center Hospital of Karamay City, Karamay, 834000, Xinjiang, China
| | - Hongbin Luo
- Department of Traditional Chinese Medicine, The Center Hospital of Karamay City, Karamay, 834000, Xinjiang, China.
| |
Collapse
|
8
|
Hegyi B, Bers DM, Bossuyt J. CaMKII signaling in heart diseases: Emerging role in diabetic cardiomyopathy. J Mol Cell Cardiol 2019; 127:246-259. [PMID: 30633874 DOI: 10.1016/j.yjmcc.2019.01.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 01/04/2019] [Indexed: 02/07/2023]
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is upregulated in diabetes and significantly contributes to cardiac remodeling with increased risk of cardiac arrhythmias. Diabetes is frequently associated with atrial fibrillation, coronary artery disease, and heart failure, which may further enhance CaMKII. Activation of CaMKII occurs downstream of neurohormonal stimulation (e.g. via G-protein coupled receptors) and involve various posttranslational modifications including autophosphorylation, oxidation, S-nitrosylation and O-GlcNAcylation. CaMKII signaling regulates diverse cellular processes in a spatiotemporal manner including excitation-contraction and excitation-transcription coupling, mechanics and energetics in cardiac myocytes. Chronic activation of CaMKII results in cellular remodeling and ultimately arrhythmogenic alterations in Ca2+ handling, ion channels, cell-to-cell coupling and metabolism. This review addresses the detrimental effects of the upregulated CaMKII signaling to enhance the arrhythmogenic substrate and trigger mechanisms in the heart. We also briefly summarize preclinical studies using kinase inhibitors and genetically modified mice targeting CaMKII in diabetes. The mechanistic understanding of CaMKII signaling, cardiac remodeling and arrhythmia mechanisms may reveal new therapeutic targets and ultimately better treatment in diabetes and heart disease in general.
Collapse
Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA.
| | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| |
Collapse
|
9
|
Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
Collapse
Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| |
Collapse
|
10
|
Qi Y, Mair N, Kummer KK, Leitner MG, Camprubí-Robles M, Langeslag M, Kress M. Identification of Chloride Channels CLCN3 and CLCN5 Mediating the Excitatory Cl - Currents Activated by Sphingosine-1-Phosphate in Sensory Neurons. Front Mol Neurosci 2018; 11:33. [PMID: 29479306 PMCID: PMC5811518 DOI: 10.3389/fnmol.2018.00033] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/24/2018] [Indexed: 12/27/2022] Open
Abstract
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid involved in numerous physiological and pathophysiological processes. We have previously reported a S1P-induced nocifensive response in mice by excitation of sensory neurons via activation of an excitatory chloride current. The underlying molecular mechanism for the S1P-induced chloride conductance remains elusive. In the present study, we identified two CLCN voltage-gated chloride channels, CLCN3 and CLCN5, which mediated a S1P-induced excitatory Cl- current in sensory neurons by combining RNA-seq, adenovirus-based gene silencing and whole-cell electrophysiological voltage-clamp recordings. Downregulation of CLCN3 and CLCN5 channels by adenovirus-mediated delivery of shRNA dramatically reduced S1P-induced Cl- current and membrane depolarization in sensory neurons. The mechanism of S1P-induced activation of the chloride current involved Rho GTPase but not Rho-associated protein kinase. Although S1P-induced potentiation of TRPV1-mediated ionic currents also involved Rho-dependent process, the lack of correlation of the S1P-activated Cl- current and the potentiation of TRPV1 by S1P suggests that CLCN3 and CLCN5 are necessary components for S1P-induced excitatory Cl- currents but not for the amplification of TRPV1-mediated currents in sensory neurons. This study provides a novel mechanistic insight into the importance of bioactive sphingolipids in nociception.
Collapse
Affiliation(s)
- Yanmei Qi
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Norbert Mair
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kai K Kummer
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael G Leitner
- Department of Neurophysiology, Philipps University of Marburg, Marburg, Germany
| | - María Camprubí-Robles
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michiel Langeslag
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| |
Collapse
|
11
|
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.
Collapse
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.
| |
Collapse
|
12
|
Tavalin SJ, Colbran RJ. CaMKII-mediated phosphorylation of GluN2B regulates recombinant NMDA receptor currents in a chloride-dependent manner. Mol Cell Neurosci 2016; 79:45-52. [PMID: 27998718 DOI: 10.1016/j.mcn.2016.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 11/29/2016] [Accepted: 12/15/2016] [Indexed: 01/09/2023] Open
Abstract
Some forms of long-term synaptic plasticity require docking of Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) to residues 1290-1309 within the intracellular C-terminal tail of the N-methyl-d-aspartate (NMDA) receptor GluN2B subunit. The phosphorylation of Ser1303 within this region destabilizes CaMKII binding. Interestingly, Ser1303 is a substrate for CaMKII itself, as well as PKC and DAPK1, but these kinases have been reported to have contradictory effects on the activity of GluN2B-containing NMDA receptors. Here, we re-assessed the effect of CaMKII on NMDA receptor desensitization in heterologous cells, as measured by the ratio of steady-state to peak currents induced during 3s agonist applications. CaMKIIα co-expression or infusion of constitutively active CaMKII limits the extent of desensitization and preserves current amplitude with repeated stimulation of recombinant GluN1A/GluN2B when examined using low intracellular chloride (Cl-) levels, characteristic of neurons beyond the first postnatal week. In contrast, CaMKIIα enhances the acute rate and extent of desensitization when intracellular Cl- concentrations are high. The apparent dependence of CaMKIIα effects on NMDA receptor desensitization on Cl- concentrations is consistent with the presence of a Ca2+-activated Cl- conductance endogenous to HEK 293 cells, which was confirmed by photolysis of caged-Ca2+. However, Ca2+-activated Cl- conductances are unaffected by CaMKIIα expression, indicating that CaMKII affects agonist-induced whole cell currents via modulation of the NMDA receptor. In support of this idea, CaMKIIα modulation of GluN2B-NMDA receptors is abrogated by the phospho-null mutation of Ser1303 in GluN2B to alanine and occluded by phospho-mimetic mutation of Ser1303 to aspartate regardless of intracellular Cl- concentration. Thus, CaMKII-mediated phosphorylation of GluN2B-containing NMDA receptors reduces desensitization at physiological (low) intracellular Cl-, perhaps serving as a feed-forward mechanism to sustain NMDA-mediated Ca2+ entry and continued CaMKII activation during learning and memory.
Collapse
Affiliation(s)
- Steven J Tavalin
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38103, United States.
| | - Roger J Colbran
- Department of Molecular Physiology & Biophysics, Brain Institute, and Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, 37232-0615, United States
| |
Collapse
|
13
|
Ma MM, Lin CX, Liu CZ, Gao M, Sun L, Tang YB, Zhou JG, Wang GL, Guan YY. Threonine532 phosphorylation in ClC-3 channels is required for angiotensin II-induced Cl(-) current and migration in cultured vascular smooth muscle cells. Br J Pharmacol 2016; 173:529-44. [PMID: 26562480 DOI: 10.1111/bph.13385] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 10/11/2015] [Accepted: 10/25/2015] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE Angiotensin II (AngII) induces migration and growth of vascular smooth muscle cell (VSMC), which is responsible for vascular remodelling in some cardiovascular diseases. Ang II also activates a Cl(-) current, but the underlying mechanism is not clear. EXPERIMENTAL APPROACH The A10 cell line and primary cultures of VSMC from control, ClC-3 channel null mice and WT mice made hypertensive with AngII infusions were used. Techniques employed included whole-cell patch clamp, co-immunoprecipitation, site-specific mutagenesis and Western blotting, KEY RESULTS In VSMC, AngII induced Cl(-) currents was carried by the chloride ion channel ClC-3. This current was absent in VSMC from ClC-3 channel null mice. The AngII-induced Cl(-) current involved interactions between ClC-3 channels and Rho-kinase 2 (ROCK2), shown by N- or C-terminal truncation of ClC-3 protein, ROCK2 siRNA and co-immunoprecipitation assays. Phosphorylation of ClC-3 channels at Thr(532) by ROCK2 was critical for AngII-induced Cl(-) current and VSMC migration. The ClC-3 T532D mutant (mutation of Thr(532) to aspartate), mimicking phosphorylated ClC-3 protein, significantly potentiated AngII-induced Cl(-) current and VSMC migration, while ClC-3 T532A (mutation of Thr(532) to alanine) had the opposite effects. AngII-induced cell migration was markedly decreased in VSMC from ClC-3 channel null mice that was insensitive to Y27632, an inhibitor of ROCK2. In addition, AngII-induced cerebrovascular remodelling was decreased in ClC-3 null mice, possibly by the ROCK2 pathway. CONCLUSIONS AND IMPLICATIONS ClC-3 protein phosphorylation at Thr(532) by ROCK2 is required for AngII-induced Cl(-) current and VSMC migration that are involved in AngII-induced vascular remodelling in hypertension.
Collapse
Affiliation(s)
- Ming-Ming Ma
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Cai-Xia Lin
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Can-Zhao Liu
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Min Gao
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Lu Sun
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Yong-Bo Tang
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Jia-Guo Zhou
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Guan-Lei Wang
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Yong-Yuan Guan
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| |
Collapse
|
14
|
Leblanc N, Forrest AS, Ayon RJ, Wiwchar M, Angermann JE, Pritchard HAT, Singer CA, Valencik ML, Britton F, Greenwood IA. Molecular and functional significance of Ca(2+)-activated Cl(-) channels in pulmonary arterial smooth muscle. Pulm Circ 2015; 5:244-68. [PMID: 26064450 DOI: 10.1086/680189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/22/2014] [Indexed: 12/31/2022] Open
Abstract
Increased peripheral resistance of small distal pulmonary arteries is a hallmark signature of pulmonary hypertension (PH) and is believed to be the consequence of enhanced vasoconstriction to agonists, thickening of the arterial wall due to remodeling, and increased thrombosis. The elevation in arterial tone in PH is attributable, at least in part, to smooth muscle cells of PH patients being more depolarized and displaying higher intracellular Ca(2+) levels than cells from normal subjects. It is now clear that downregulation of voltage-dependent K(+) channels (e.g., Kv1.5) and increased expression and activity of voltage-dependent (Cav1.2) and voltage-independent (e.g., canonical and vanilloid transient receptor potential [TRPC and TRPV]) Ca(2+) channels play an important role in the functional remodeling of pulmonary arteries in PH. This review focuses on an anion-permeable channel that is now considered a novel excitatory mechanism in the systemic and pulmonary circulations. It is permeable to Cl(-) and is activated by a rise in intracellular Ca(2+) concentration (Ca(2+)-activated Cl(-) channel, or CaCC). The first section outlines the biophysical and pharmacological properties of the channel and ends with a description of the molecular candidate genes postulated to encode for CaCCs, with particular emphasis on the bestrophin and the newly discovered TMEM16 and anoctamin families of genes. The second section provides a review of the various sources of Ca(2+) activating CaCCs, which include stimulation by mobilization from intracellular Ca(2+) stores and Ca(2+) entry through voltage-dependent and voltage-independent Ca(2+) channels. The third and final section summarizes recent findings that suggest a potentially important role for CaCCs and the gene TMEM16A in PH.
Collapse
Affiliation(s)
- Normand Leblanc
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Abigail S Forrest
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Ramon J Ayon
- Department of Medicine, University of Illinois, Chicago, Illinois, USA
| | - Michael Wiwchar
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Jeff E Angermann
- School of Community Health Sciences, University of Nevada, Reno, Nevada, USA
| | - Harry A T Pritchard
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
| | - Cherie A Singer
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Maria L Valencik
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Fiona Britton
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
| |
Collapse
|
15
|
Yamada T, Bhate MP, Strange K. Regulatory phosphorylation induces extracellular conformational changes in a CLC anion channel. Biophys J 2013; 104:1893-904. [PMID: 23663832 DOI: 10.1016/j.bpj.2013.03.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 10/26/2022] Open
Abstract
CLH-3b is a CLC-1/2/Ka/Kb channel homolog activated by meiotic cell cycle progression and cell swelling. Channel inhibition occurs by GCK-3 kinase-mediated phosphorylation of serine residues on the cytoplasmic C-terminus linker connecting CBS1 and CBS2. Two conserved aromatic amino acid residues located on the intracellular loop connecting membrane helices H and I and α1 of CBS2 are required for transducing phosphorylation changes into changes in channel activity. Helices H and I form part of the interface between the two subunits that comprise functional CLC channels. Using a cysteine-less CLH-3b mutant, we demonstrate that the sulfhydryl reagent reactivity of substituted cysteines at the subunit interface changes dramatically during GCK-3-mediated channel inhibition and that these changes are prevented by mutation of the H-I loop/CBS2 α1 signal transduction domain. We also show that GCK-3 modifies Zn(2+) inhibition, which is thought to be mediated by the common gating process. These and other results suggest that phosphorylation of the cytoplasmic C-terminus inhibits CLH-3b by inducing subunit interface conformation changes that activate the common gate. Our findings have important implications for understanding CLC regulation by diverse signaling mechanisms and for understanding the structure/function relationships that mediate intraprotein communication in this important family of Cl(-) transport proteins.
Collapse
Affiliation(s)
- Toshiki Yamada
- Boylan Center for Cellular and Molecular Physiology, Mount Desert Island Biological Laboratory, Salisbury Cove, Maine, USA
| | | | | |
Collapse
|
16
|
Satoh H, Qu L, Suzuki H, Saitow F. Depolarization-induced depression of inhibitory transmission in cerebellar Purkinje cells. Physiol Rep 2013; 1:e00061. [PMID: 24303140 PMCID: PMC3835016 DOI: 10.1002/phy2.61] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 07/24/2013] [Accepted: 07/25/2013] [Indexed: 11/07/2022] Open
Abstract
Several forms of depolarization-induced plasticity in inhibitory transmission have been reported to occur in cerebellar Purkinje cells (PCs), namely depolarization-induced suppression of inhibition (DSI), depolarization-induced potentiation of inhibition (DPI), and rebound potentiation (RP). Here, we describe another form of synaptic plasticity for gamma-amino butyric acid (GABA)ergic transmission in PCs. Immediately following depolarization trains in a PC, evoked inhibitory postsynaptic currents (eIPSCs) changed their direction from outward to inward currents under a recording condition in which eIPSCs were elicited as an outward current. Subsequently, the eIPSC amplitude remained depressed (depolarization-induced depression of inhibition [DDI]) for more than 20 min under the blockade of cannabinoid and N-methyl-D-aspartic acid (NMDA) receptor-mediated DSI and DPI, respectively. This DDI was completely abolished by intracellular infusion of the fast Ca(2+)-chelating agent BAPTA and by inhibition of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Furthermore, DDI was strongly suppressed by calcium-activated chloride channel (CaCC) blockers, while an inhibitor of cation-chloride cotransporters (CCCs) partially blocked DDI during the early phase. Exogenous GABA-induced inhibition of spontaneous spike activity was attenuated in ∼50% of the PCs by climbing fiber stimulation-induced depolarization. These results suggest that activation of both CaCCs and CCCs was necessary for alteration of [Cl(-)]i after activation of CaMKII following elevation of [Ca(2+)]i in PCs. DDI may provide another mechanism for regulation of inhibitory inputs to PCs within the neuronal networks of the cerebellar cortex.
Collapse
Affiliation(s)
- Hiromasa Satoh
- Department of Pharmacology, Nippon Medical School Tokyo, 113-8602, Japan
| | | | | | | |
Collapse
|
17
|
Bossus M, Charmantier G, Blondeau-Bidet E, Valletta B, Boulo V, Lorin-Nebel C. The ClC-3 chloride channel and osmoregulation in the European sea bass, Dicentrarchus labrax. J Comp Physiol B 2013; 183:641-62. [PMID: 23292336 DOI: 10.1007/s00360-012-0737-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/27/2012] [Accepted: 11/23/2012] [Indexed: 11/29/2022]
Abstract
Dicentrarchus labrax migrates between sea (SW), brackish and fresh water (FW) where chloride concentrations and requirements for chloride handling change: in FW, fish absorb chloride and restrict renal losses; in SW, they excrete chloride. In this study, the expression and localization of ClC-3 and Na(+)/K(+)-ATPase (NKA) were studied in fish adapted to SW, or exposed to FW from 10 min to 30 days. In gills, NKA-α1 subunit expression transiently increased from 10 min and reached a stabilized intermediate expression level after 24 h in FW. ClC-3 co-localized with NKA in the basolateral membrane of mitochondria-rich cells (MRCs) at all conditions. The intensity of MRC ClC-3 immunostaining was significantly higher (by 50 %) 1 h after the transfer to FW, whereas the branchial ClC-3 protein expression was 30 % higher 7 days after the transfer as compared to SW. This is consistent with the increased number of immunopositive MRCs (immunostained for NKA and ClC-3). However, the ClC-3 mRNA expression was significantly lower in FW gills. In the kidney, after FW transfer, a transient decrease in NKA-α1 subunit expression was followed by significantly higher stable levels from 24 h. The low ClC-3 protein expression detected at both salinities was not observed by immunocytochemistry in the SW kidney; ClC-3 was localized in the basal membrane of the collecting ducts and tubules 7 and 30 days after transfer to FW. Renal ClC-3 mRNA expression, however, seemed higher in SW than in FW. The potential role of this chloride channel ClC-3 in osmoregulatory and osmosensing mechanisms is discussed.
Collapse
Affiliation(s)
- Maryline Bossus
- Equipe Adaptation Ecophysiologique et Ontogenèse, UMR5119 - EcoSyM, UM2-UM1-CNRS-IRD-IFREMER, cc 092, Place E. Bataillon, 34095 Montpellier cedex 05, France.
| | | | | | | | | | | |
Collapse
|
18
|
Zhang H, Zhu L, Zuo W, Luo H, Mao J, Ye D, Li Y, Liu S, Wei Y, Ye W, Chen L, Wang L. The ClC-3 chloride channel protein is a downstream target of cyclin D1 in nasopharyngeal carcinoma cells. Int J Biochem Cell Biol 2013; 45:672-83. [DOI: 10.1016/j.biocel.2012.12.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 12/16/2012] [Indexed: 12/26/2022]
|
19
|
Matchkov VV, Secher Dam V, Bødtkjer DMB, Aalkjær C. Transport and Function of Chloride in Vascular Smooth Muscles. J Vasc Res 2013; 50:69-87. [DOI: 10.1159/000345242] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 10/16/2012] [Indexed: 12/12/2022] Open
|
20
|
Ganapathi SB, Wei SG, Zaremba A, Lamb FS, Shears SB. Functional regulation of ClC-3 in the migration of vascular smooth muscle cells. Hypertension 2013; 61:174-9. [PMID: 23150504 PMCID: PMC3521842 DOI: 10.1161/hypertensionaha.112.194209] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 10/22/2012] [Indexed: 12/17/2022]
Abstract
Migration of vascular smooth muscle cells (VSMCs) into neointima contributes to atherosclerosis and restenosis. This migration requires coordinated plasmalemmal fluxes of water and ions. Here, we show that aortic VSMC migration depends on the regulation of transmembrane Cl(-) flux by ClC-3, a Cl(-) channel/transporter. The contribution of ClC-3 to plasmalemmal Cl(-) current was studied in VSMCs by electrophysiological recordings. Cl(-) current was negligible in cells perfused with 0 [Ca(2+)]. Raising intracellular [Ca(2+)] to 0.5 μM activated a Cl(-) current (I(Cl.Ca)), approximately half of which was eliminated on inhibition by KN-93 of calmodulin-dependent protein kinase II. I(Cl.Ca) was also halved by inositol-3,4,5,6-tetrakisphosphate, a cellular signal with the biological function of specifically preventing calmodulin-dependent protein kinase II from activating I(Cl.Ca). Gene disruption of ClC-3 reduced I(Cl.Ca) by 50%. Moreover, I(Cl.Ca) in the ClC-3 null VSMCs was not affected by either KN-93 or inositol-3,4,5,6-tetrakisphosphate. We conclude that I(Cl.Ca) is composed of 2 components, one is ClC-3 independent whereas the other is ClC-3 dependent, activated by calmodulin-dependent protein kinase II and inhibited by inositol-3,4,5,6-tetrakisphosphate. We also assayed VSMC migration in transwell assays. Migration was halved in ClC-3 null cells versus wild-type cells. In addition, inhibition of ClC-3 by niflumic acid, KN-93, or inositol-3,4,5,6-tetrakisphosphate each reduced cell migration in wild-type cells but not in ClC-3 null cells. These cell-signaling roles of ClC-3 in VSMC migration suggest new therapeutic approaches to vascular remodeling diseases.
Collapse
MESH Headings
- Animals
- Aorta/cytology
- Aorta/drug effects
- Aorta/metabolism
- Benzylamines/pharmacology
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/antagonists & inhibitors
- Cell Movement/drug effects
- Cell Movement/physiology
- Cells, Cultured
- Chloride Channels/genetics
- Chloride Channels/metabolism
- Inositol Phosphates/pharmacology
- Mice
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Niflumic Acid/pharmacology
- Protein Kinase Inhibitors/pharmacology
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Sulfonamides/pharmacology
Collapse
Affiliation(s)
- Sindura B. Ganapathi
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| | - Shun-Guang Wei
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| | - Angelika Zaremba
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| | - Fred S. Lamb
- Department of Pediatrics, University of Iowa Children’s Hospital, Iowa City, Iowa 52242, USA
| | - Stephen B. Shears
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| |
Collapse
|
21
|
Calcium entry via TRPC1 channels activates chloride currents in human glioma cells. Cell Calcium 2012; 53:187-94. [PMID: 23261316 DOI: 10.1016/j.ceca.2012.11.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 10/08/2012] [Accepted: 11/19/2012] [Indexed: 12/11/2022]
Abstract
Malignant gliomas are highly invasive brain cancers that carry a dismal prognosis. Recent studies indicate that Cl(-) channels facilitate glioma cell invasion by promoting hydrodynamic cell shape and volume changes. Here we asked how Cl(-) channels are regulated in the context of migration. Using patch-clamp recordings we show Cl(-) currents are activated by physiological increases of [Ca(2+)]i to 65 and 180nM. Cl(-) currents appear to be mediated by ClC-3, a voltage-gated, CaMKII-regulated Cl(-) channel highly expressed by glioma cells. ClC-3 channels colocalized with TRPC1 on caveolar lipid rafts on glioma cell processes. Using perforated-patch electrophysiological recordings, we demonstrate that inducible knockdown of TRPC1 expression with shRNA significantly inhibited glioma Cl(-) currents in a Ca(2+)-dependent fashion, placing Cl(-) channels under the regulation of Ca(2+) entry via TRPC1. In chemotaxis assays epidermal growth factor (EGF)-induced invasion was inhibition by TRPC1 knockdown to the same extent as pharmacological block of Cl(-) channels. Thus endogenous glioma Cl(-) channels are regulated by TRPC1. Cl(-) channels could be an important downstream target of TRPC1 in many other cells types, coupling elevations in [Ca(2+)]i to the shape and volume changes associated with migrating cells.
Collapse
|
22
|
Farmer LM, Le BN, Nelson DJ. CLC-3 chloride channels moderate long-term potentiation at Schaffer collateral-CA1 synapses. J Physiol 2012; 591:1001-15. [PMID: 23165767 DOI: 10.1113/jphysiol.2012.243485] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The chloride channel CLC-3 is expressed in the brain on synaptic vesicles and postsynaptic membranes. Although CLC-3 is broadly expressed throughout the brain, the CLC-3 knockout mouse shows complete, selective postnatal neurodegeneration of the hippocampus, suggesting a crucial role for the channel in maintaining normal brain function. CLC-3 channels are functionally linked to NMDA receptors in the hippocampus; NMDA receptor-dependent Ca(2+) entry, activation of Ca(2+)/calmodulin kinase II and subsequent gating of CLC-3 link the channels via a Ca(2+)-mediated feedback loop. We demonstrate that loss of CLC-3 at mature synapses increases long-term potentiation from 135 ± 4% in the wild-type slice preparation to 154 ± 7% above baseline (P < 0.001) in the knockout; therefore, the contribution of CLC-3 is to reduce synaptic potentiation by ∼40%. Using a decoy peptide representing the Ca(2+)/calmodulin kinase II phosphorylation site on CLC-3, we show that phosphorylation of CLC-3 is required for its regulatory function in long-term potentiation. CLC-3 is also expressed on synaptic vesicles; however, our data suggest functionally separable pre- and postsynaptic roles. Thus, CLC-3 confers Cl(-) sensitivity to excitatory synapses, controls the magnitude of long-term potentiation and may provide a protective limit on Ca(2+) influx.
Collapse
Affiliation(s)
- Laurel M Farmer
- Department of Neurobiology, Pharmacology and Physiology, The University of Chicago, Chicago, IL 60637, USA
| | | | | |
Collapse
|
23
|
Miyazaki H, Yamada T, Parton A, Morrison R, Kim S, Beth AH, Strange K. CLC anion channel regulatory phosphorylation and conserved signal transduction domains. Biophys J 2012; 103:1706-18. [PMID: 23083714 DOI: 10.1016/j.bpj.2012.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/20/2012] [Accepted: 09/04/2012] [Indexed: 12/01/2022] Open
Abstract
The signaling mechanisms that regulate CLC anion channels are poorly understood. Caenorhabditis elegans CLH-3b is a member of the CLC-1/2/Ka/Kb channel subfamily. CLH-3b is activated by meiotic cell-cycle progression and cell swelling. Inhibition is brought about by GCK-3 kinase-mediated phosphorylation of S742 and S747 located on a ∼176 amino acid disordered domain linking CBS1 and CBS2. Much of the inter-CBS linker is dispensable for channel regulation. However, deletion of a 14 amino acid activation domain encompassing S742 and S747 inhibits channel activity to the same extent as GCK-3. The crystal structure of CmCLC demonstrated that CBS2 interfaces extensively with an intracellular loop connecting membrane helices H and I, the C-terminus of helix D, and a short linker connecting helix R to CBS1. Point mutagenesis of this interface identified two highly conserved aromatic amino acid residues located in the H-I loop and the first α-helix (α1) of CBS2. Mutation of either residue to alanine rendered CLH-3b insensitive to GCK-3 inhibition. We suggest that the dephosphorylated activation domain normally interacts with CBS1 and/or CBS2, and that conformational information associated with this interaction is transduced through a conserved signal transduction module comprising the H-I loop and CBS2 α1.
Collapse
Affiliation(s)
- Hiroaki Miyazaki
- Boylan Center for Cellular and Molecular Physiology, Mount Desert Island Biological Laboratory, Salisbury Cove, Maine, USA
| | | | | | | | | | | | | |
Collapse
|
24
|
He XD, Goyal RK. CaMKII inhibition hyperpolarizes membrane and blocks nitrergic IJP by closing a Cl(-) conductance in intestinal smooth muscle. Am J Physiol Gastrointest Liver Physiol 2012; 303:G240-6. [PMID: 22538403 PMCID: PMC3404568 DOI: 10.1152/ajpgi.00102.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The ionic basis of nitrergic "slow'" inhibitory junction potential (sIJP) is not fully understood. The purpose of the present study was to determine the nature and the role of calmodulin-dependent protein kinase II (CaMKII)-dependent ion conductance in nitrergic neurotransmission at the intestinal smooth muscle neuromuscular junction. Studies were performed in guinea pig ileum. The modified Tomita bath technique was used to induce passive hyperpolarizing electrotonic potentials (ETP) and membrane potential change due to sIJP or drug treatment in the same cell. Changes in membrane potential and ETP were recorded in the same smooth muscle cell, using sharp microelectrode. Nitrergic IJP was elicited by electrical field stimulation in nonadrenergic, noncholinergic conditions and chemical block of purinergic IJP. Modification of ETP during hyperpolarization reflected active conductance change in the smooth muscle. Nitrergic IJP was associated with decreased membrane conductance. The CAMKII inhibitor KN93 but not KN92, the Cl(-) channel blocker niflumic acid (NFA), and the K(ATP)-channel opener cromakalim hyperpolarized the membrane. However, KN93 and NFA were associated with decreased and cromakalim was associated with increased membrane conductance. After maximal NFA-induced hyperpolarization, hyperpolarization associated with KN93 or sIJP was not seen, suggesting a saturation block of the Cl(-) channel signaling. These studies suggest that inhibition of CaMKII-dependent Cl(-) conductance mediates nitrergic sIJP by causing maximal closure of the Cl(-) conductance.
Collapse
Affiliation(s)
- Xue-Dao He
- Center for Swallowing and Motility Disorders, Veterans Affairs Boston HealthCare System and Harvard Medical School, Boston, Massachusetts
| | - Raj K. Goyal
- Center for Swallowing and Motility Disorders, Veterans Affairs Boston HealthCare System and Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
25
|
Miyazaki H, Strange K. Differential regulation of a CLC anion channel by SPAK kinase ortholog-mediated multisite phosphorylation. Am J Physiol Cell Physiol 2012; 302:C1702-12. [PMID: 22357738 DOI: 10.1152/ajpcell.00419.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Shrinkage-induced inhibition of the Caenorhabditis elegans cell volume and cell cycle-dependent CLC anion channel CLH-3b occurs by concomitant phosphorylation of S742 and S747, which are located on a 175 amino acid linker domain between cystathionine-β-synthase 1 (CBS1) and CBS2. Phosphorylation is mediated by the SPAK kinase homolog GCK-3 and is mimicked by substituting serine residues with glutamate. Type 1 serine/threonine protein phosphatases mediate swelling-induced channel dephosphorylation. S742E/S747E double mutant channels are constitutively inactive and cannot be activated by cell swelling. S742E and S747E mutant channels were fully active in the absence of GCK-3 and were inactive when coexpressed with the kinase. Both channels responded to cell volume changes. However, the S747E mutant channel activated and inactivated in response to cell swelling and shrinkage, respectively, much more slowly than either wild-type or S742E mutant channels. Slower activation and inactivation of S747E was not due to altered rates of dephosphorylation or dephosphorylation-dependent conformational changes. GCK-3 binds to the 175 amino acid inter-CBS linker domain. Coexpression of wild-type CLH-3b and GCK-3 with either wild-type or S742E linkers gave rise to similar channel activity and regulation. In contrast, coexpression with the S747E linker greatly enhanced basal channel activity and increased the rate of shrinkage-induced channel inactivation. Our findings suggest the intriguing possibility that the phosphorylation state of S742 in S747E mutant channels modulates GCK-3/channel interaction and hence channel phosphorylation. These results provide a foundation for further detailed studies of the role of multisite phosphorylation in regulating CLH-3b and GCK-3 activity.
Collapse
Affiliation(s)
- Hiroaki Miyazaki
- Boylan Center for Cellular and Molecular Physiology, Mount Desert Island Biological Laboratory, Salisbury Cove, Maine 04672, USA
| | | |
Collapse
|
26
|
Cuddapah VA, Habela CW, Watkins S, Moore LS, Barclay TTC, Sontheimer H. Kinase activation of ClC-3 accelerates cytoplasmic condensation during mitotic cell rounding. Am J Physiol Cell Physiol 2011; 302:C527-38. [PMID: 22049206 DOI: 10.1152/ajpcell.00248.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
"Mitotic cell rounding" describes the rounding of mammalian cells before dividing into two daughter cells. This shape change requires coordinated cytoskeletal contraction and changes in osmotic pressure. While considerable research has been devoted to understanding mechanisms underlying cytoskeletal contraction, little is known about how osmotic gradients are involved in cell division. Here we describe cytoplasmic condensation preceding cell division, termed "premitotic condensation" (PMC), which involves cells extruding osmotically active Cl(-) via ClC-3, a voltage-gated channel/transporter. This leads to a decrease in cytoplasmic volume during mitotic cell rounding and cell division. Using a combination of time-lapse microscopy and biophysical measurements, we demonstrate that PMC involves the activation of ClC-3 by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) in human glioma cells. Knockdown of endogenous ClC-3 protein expression eliminated CaMKII-dependent Cl(-) currents in dividing cells and impeded PMC. Thus, kinase-dependent changes in Cl(-) conductance contribute to an outward osmotic pressure in dividing cells, which facilitates cytoplasmic condensation preceding cell division.
Collapse
|
27
|
Effects of ion channels on proliferation in cultured human cardiac fibroblasts. J Mol Cell Cardiol 2011; 51:198-206. [DOI: 10.1016/j.yjmcc.2011.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 04/24/2011] [Accepted: 05/11/2011] [Indexed: 01/01/2023]
|
28
|
Ferrera L, Caputo A, Galietta LJV. TMEM16A protein: a new identity for Ca(2+)-dependent Cl⁻ channels. Physiology (Bethesda) 2011; 25:357-63. [PMID: 21186280 DOI: 10.1152/physiol.00030.2010] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca(+)-dependent Cl⁻ channels (CaCCs) play a variety of physiological roles in different organs and tissues, including transepithelial Cl⁻ secretion, smooth muscle contraction, regulation of neuronal excitability, and transduction of sensory stimuli. The recent identification of TMEM16A protein as an important component of CaCCs should allow a better understanding of their physiological role, structure-function relationship, and regulatory mechanisms.
Collapse
Affiliation(s)
- Loretta Ferrera
- Laboratory of Molecular Genetics, Istituto Giannina Gaslini, Genova, Italy
| | | | | |
Collapse
|
29
|
Strange K. Putting the pieces together: a crystal clear window into CLC anion channel regulation. Channels (Austin) 2011; 5:101-5. [PMID: 21317557 DOI: 10.4161/chan.5.2.14694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
CLC anion transport proteins function as Cl (-) channels and Cl (-) /H (+) exchangers and are found in all major groups of life including archaebacteria. Early electrophysiological studies suggested that CLC anion channels have two pores that are opened and closed independently by a "fast" gating process operating on a millisecond timescale, and a "common" or "slow" gate that opens and closes both pores simultaneously with a timescale of seconds (Figure 1A). Subsequent biochemical and molecular experiments suggested that CLC channels/transporters are homodomeric proteins ( 1-3) .
Collapse
Affiliation(s)
- Kevin Strange
- Boylan Center for Cellular and Molecular Physiology, Mount Desert Island Biological Laboratory; Salisbury Cove, ME, USA.
| |
Collapse
|
30
|
Lithium inhibits cell volume regulation by acting on chloride channels and modifies ultrastructures of the cell membrane in nasopharyngeal carcinoma cells. Eur J Pharmacol 2010; 641:88-95. [DOI: 10.1016/j.ejphar.2010.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/10/2010] [Accepted: 05/06/2010] [Indexed: 11/18/2022]
|
31
|
Matsuda JJ, Filali MS, Moreland JG, Miller FJ, Lamb FS. Activation of swelling-activated chloride current by tumor necrosis factor-alpha requires ClC-3-dependent endosomal reactive oxygen production. J Biol Chem 2010; 285:22864-73. [PMID: 20479003 DOI: 10.1074/jbc.m109.099838] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
ClC-3 is a Cl(-)/H(+) antiporter required for cytokine-induced intraendosomal reactive oxygen species (ROS) generation by Nox1. ClC-3 current is distinct from the swelling-activated chloride current (ICl(swell)), but overexpression of ClC-3 can activate currents that resemble ICl(swell). Because H(2)O(2) activates ICl(swell) directly, we hypothesized that ClC-3-dependent, endosomal ROS production activates ICl(swell). Whole-cell perforated patch clamp methods were used to record Cl(-) currents in cultured aortic vascular smooth muscle cells from wild type (WT) and ClC-3 null mice. Under isotonic conditions, tumor necrosis factor-alpha (TNF-alpha) (10 ng/ml) activated outwardly rectifying Cl(-) currents with time-dependent inactivation in WT but not ClC-3 null cells. Inhibition by tamoxifen (10 microm) and by hypertonicity (340 mosm) identified them as ICl(swell). ICl(swell) was also activated by H(2)O(2) (500 microm), and the effect of TNF-alpha was completely inhibited by polyethylene glycol-catalase. ClC-3 expression induced ICl(swell) in ClC-3 null cells in the absence of swelling or TNF-alpha, and this effect was also blocked by catalase. ICl(swell) activation by hypotonicity (240 mosm) was only partially inhibited by catalase, and the size of these currents did not differ between WT and ClC-3 null cells. Disruption of endosome trafficking with either mutant Rab5 (S34N) or Rab11 (S25N) inhibited TNF-alpha-mediated activation of ICl(swell). Thrombin also activates ROS production by Nox1 but not in endosomes. Thrombin caused H(2)O(2)-dependent activation of ICl(swell), but this effect was not ClC-3- or Rab5-dependent. Thus, activation of ICl(swell) by TNF-alpha requires ClC-3-dependent endosomal H(2)O(2) production. This demonstrates a functional link between two distinct anion currents, ClC-3 and ICl(swell).
Collapse
Affiliation(s)
- James J Matsuda
- Department of Pediatrics, University of Iowa Children's Hospital and the University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA
| | | | | | | | | |
Collapse
|
32
|
Cuddapah VA, Sontheimer H. Molecular interaction and functional regulation of ClC-3 by Ca2+/calmodulin-dependent protein kinase II (CaMKII) in human malignant glioma. J Biol Chem 2010; 285:11188-96. [PMID: 20139089 DOI: 10.1074/jbc.m109.097675] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Glioblastoma multiforme is the most common and lethal primary brain cancer in adults. Tumor cells diffusely infiltrate the brain making focal surgical and radiation treatment challenging. The invasion of glioma cells into normal brain is facilitated by the activity of ion channels aiding dynamic regulation of cell volume. Recent studies have specifically implicated ClC-3, a voltage-gated chloride channel, in this process. However, the interaction between ClC-3 activity and cell movement is poorly understood. Here, we demonstrate that ClC-3 is highly expressed on the plasma membrane of human glioma cells where its activity is regulated through phosphorylation via Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Intracellular infusion of autoactivated CaMKII via patch pipette enhanced chloride currents 3-fold, and this regulation was inhibited by autocamtide-2 related inhibitory peptide, a CaMKII-specific inhibitor. CaMKII modulation of chloride currents was also lost upon stable small hairpin RNA knockdown of ClC-3 channels indicating a specific interaction of ClC-3 and CaMKII. In ClC-3-expressing cells, inhibition of CaMKII reduced glioma invasion to the same extent as direct inhibition of ClC-3. The importance of the molecular interaction of ClC-3 and CaMKII is further supported by our finding that CaMKII co-localizes and co-immunoprecipitates with ClC-3. ClC-3 and CaMKII also co-immunoprecipitate in tissue biopsies from patients diagnosed with grade IV glioblastoma. These tumor samples show 10-fold higher ClC-3 protein expression than nonmalignant brain. These data suggest that CaMKII is a molecular link translating intracellular calcium changes, which are intrinsically associated with glioma migration, to changes in ClC-3 conductance required for cell movement.
Collapse
Affiliation(s)
- Vishnu Anand Cuddapah
- Department of Neurobiology and Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | | |
Collapse
|
33
|
Matsuda JJ, Filali MS, Collins MM, Volk KA, Lamb FS. The ClC-3 Cl-/H+ antiporter becomes uncoupled at low extracellular pH. J Biol Chem 2009; 285:2569-79. [PMID: 19926787 DOI: 10.1074/jbc.m109.018002] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adenovirus expressing ClC-3 (Ad-ClC-3) induces Cl(-)/H(+) antiport current (I(ClC-3)) in HEK293 cells. The outward rectification and time dependence of I(ClC-3) closely resemble an endogenous HEK293 cell acid-activated Cl(-) current (ICl(acid)) seen at extracellular pH <or= 5.5. ICl(acid) was present in smooth muscle cells from wild-type but not ClC-3 null mice. We therefore sought to determine whether these currents were related. ICl(acid) was larger in cells expressing Ad-ClC-3. Protons shifted the reversal potential (E(rev)) of I(ClC-3) between pH 8.2 and 6.2, but not pH 6.2 and 5.2, suggesting that Cl(-) and H(+) transport become uncoupled at low pH. At pH 4.0 E(rev) was completely Cl(-) dependent (55.8 +/- 2.3 mV/decade). Several findings linked ClC-3 with native ICl(acid); 1) RNA interference directed at ClC-3 message reduced native ICl(acid); 2) removal of the extracellular "fast gate" (E224A) produced large currents that were pH-insensitive; and 3) wild-type I(ClC-3) and ICl(acid) were both inhibited by (2-sulfonatoethyl)methanethiosulfonate (MTSES; 10-500 microm)-induced alkanethiolation at exposed cysteine residues. However, a ClC-3 mutant lacking four extracellular cysteine residues (C103_P130del) was completely resistant to MTSES. C103_P130del currents were still acid-activated, but could be distinguished from wild-type I(ClC-3) and from native ICl(acid) by a much slower response to low pH. Thus, ClC-3 currents are activated by protons and ClC-3 protein may account for native ICl(acid). Low pH uncouples Cl(-)/H(+) transport so that at pH 4.0 ClC-3 behaves as an anion-selective channel. These findings have important implications for the biology of Cl(-)/H(+) antiporters and perhaps for pH regulation in highly acidic intracellular compartments.
Collapse
Affiliation(s)
- James J Matsuda
- Department of Pediatrics, University of Iowa Children's Hospital, Iowa City, Iowa 52242, USA
| | | | | | | | | |
Collapse
|
34
|
Deriy LV, Gomez EA, Jacobson DA, Wang X, Hopson JA, Liu XY, Zhang G, Bindokas VP, Philipson LH, Nelson DJ. The granular chloride channel ClC-3 is permissive for insulin secretion. Cell Metab 2009; 10:316-23. [PMID: 19808024 PMCID: PMC2778193 DOI: 10.1016/j.cmet.2009.08.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 07/06/2009] [Accepted: 08/18/2009] [Indexed: 11/29/2022]
Abstract
Insulin secretion from pancreatic beta cells is dependent on maturation and acidification of the secretory granule, processes necessary for prohormone convertase cleavage of proinsulin. Previous studies in isolated beta cells revealed that acidification may be dependent on the granule membrane chloride channel ClC-3, in a step permissive for a regulated secretory response. In this study, immuno-EM of beta cells revealed colocalization of ClC-3 and insulin on secretory granules. Clcn3(-/-) mice as well as isolated islets demonstrate impaired insulin secretion; Clcn3(-/-) beta cells are defective in regulated insulin exocytosis and granular acidification. Increased amounts of proinsulin were found in the majority of secretory granules in the Clcn3(-/-) mice, while in Clcn3(+/+) cells, proinsulin was confined to the immature secretory granules. These results demonstrate that in pancreatic beta cells, chloride channels, specifically ClC-3, are localized on insulin granules and play a role in insulin processing as well as insulin secretion through regulation of granular acidification.
Collapse
Affiliation(s)
- Ludmila V Deriy
- Department of Neurobiology, Pharmacology, and Physiology, The University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Flores CA, Cid LP, Sepúlveda FV, Niemeyer MI. TMEM16 proteins: the long awaited calcium-activated chloride channels? ACTA ACUST UNITED AC 2009; 42:993-1001. [PMID: 19784506 DOI: 10.1590/s0100-879x2009005000028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 08/12/2009] [Indexed: 11/22/2022]
Abstract
Currents mediated by calcium-activated chloride channels (CaCCs), observed for the first time in Xenopus oocytes, have been recorded in many cells and tissues ranging from different types of neurons to epithelial and muscle cells. CaCCs play a role in the regulation of excitability in neurons including sensory receptors. In addition, they are crucial mediators of chloride movements in epithelial cells where their activity regulates electrolyte and fluid transport. The roles of CaCCs, particularly in epithelia, are briefly reviewed with emphasis on their function in secretory epithelia. The recent identification by three independent groups, using different strategies, of TMEM16A as the molecular counterpart of the CaCC is discussed. TMEM16A is part of a family that has 10 other members in mice. The discovery of the potential TMEM16 anion channel activity opens the way for the molecular investigation of the role of these anion channels in specific cells and in organ physiology and pathophysiology. The identification of TMEM16A protein as a CaCC chloride channel molecule represents a great triumph of scientific perseverance and ingenuity. The varied approaches used by the three independent research groups also augur well for the solidity of the discovery.
Collapse
Affiliation(s)
- C A Flores
- Centro de Estudios Científicos (CECS), Valdivia, Chile
| | | | | | | |
Collapse
|
36
|
Shears SB. Molecular basis for the integration of inositol phosphate signaling pathways via human ITPK1. ACTA ACUST UNITED AC 2009; 49:87-96. [PMID: 19200440 DOI: 10.1016/j.advenzreg.2008.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Stephen B Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
37
|
Falin RA, Morrison R, Ham AJL, Strange K. Identification of regulatory phosphorylation sites in a cell volume- and Ste20 kinase-dependent ClC anion channel. ACTA ACUST UNITED AC 2008; 133:29-42. [PMID: 19088383 PMCID: PMC2606941 DOI: 10.1085/jgp.200810080] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Changes in phosphorylation regulate the activity of various ClC anion transport proteins. However, the physiological context under which such regulation occurs and the signaling cascades that mediate phosphorylation are poorly understood. We have exploited the genetic model organism Caenorhabditis elegans to characterize ClC regulatory mechanisms and signaling networks. CLH-3b is a ClC anion channel that is expressed in the worm oocyte and excretory cell. Channel activation occurs in response to oocyte meiotic maturation and swelling via serine/threonine dephosphorylation mediated by the type I phosphatases GLC-7alpha and GLC-7beta. A Ste20 kinase, germinal center kinase (GCK)-3, binds to the cytoplasmic C terminus of CLH-3b and inhibits channel activity in a phosphorylation-dependent manner. Analysis of hyperpolarization-induced activation kinetics suggests that phosphorylation may inhibit the ClC fast gating mechanism. GCK-3 is an ortholog of mammalian SPAK and OSR1, kinases that bind to, phosphorylate, and regulate the cell volume-dependent activity of mammalian cation-Cl(-) cotransporters. Using mass spectrometry and patch clamp electrophysiology, we demonstrate here that CLH-3b is a target of regulatory phosphorylation. Concomitant phosphorylation of S742 and S747, which are located 70 and 75 amino acids downstream from the GCK-3 binding site, are required for kinase-mediated channel inhibition. In contrast, swelling-induced channel activation occurs with dephosphorylation of S747 alone. Replacement of both S742 and S747 with glutamate gives rise to kinase- and swelling-insensitive channels that exhibit activity and biophysical properties similar to those of wild-type CLH-3b inhibited by GCK-3. Our studies provide novel insights into ClC regulation and mechanisms of cell volume signaling, and provide the foundation for studies aimed at defining how conformational changes in the cytoplasmic C terminus alter ClC gating and function in response to intracellular signaling events.
Collapse
Affiliation(s)
- Rebecca A Falin
- Department of Anesthesiology and Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | | | | |
Collapse
|
38
|
Mitchell J, Wang X, Zhang G, Gentzsch M, Nelson DJ, Shears SB. An expanded biological repertoire for Ins(3,4,5,6)P4 through its modulation of ClC-3 function. Curr Biol 2008; 18:1600-5. [PMID: 18951024 DOI: 10.1016/j.cub.2008.08.073] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 08/08/2008] [Accepted: 08/28/2008] [Indexed: 01/01/2023]
Abstract
Ins(3,4,5,6)P(4) inhibits plasma membrane Cl(-) flux in secretory epithelia [1]. However, in most other mammalian cells, receptor-dependent elevation of Ins(3,4,5,6)P(4) levels is an "orphan" response that lacks biological significance [2]. We set out to identify Cl(-) channel(s) and/or transporter(s) that are regulated by Ins(3,4,5,6)P4 in vivo. Several candidates [3-5] were excluded through biophysical criteria, electrophysiological analysis, and confocal immunofluorescence microscopy. Then, we heterologously expressed ClC-3 in the plasma membrane of HEK293-tsA201 cells; whole-cell patch-clamp analysis showed Ins(3,4,5,6)P4 to inhibit Cl(-) conductance through ClC-3. Next, we heterologously expressed ClC-3 in the early endosomal compartment of BHK cells; by fluorescence ratio imaging of endocytosed FITC-transferrin, we recorded intra-endosomal pH, an in situ biosensor for Cl(-) flux across endosomal membranes [6]. A cell-permeant, bioactivatable Ins(3,4,5,6)P4 analog elevated endosomal pH from 6.1 to 6.6, reflecting inhibition of ClC-3. Finally, Ins(3,4,5,6)P(4) inhibited endogenous ClC-3 conductance in postsynaptic membranes of neonatal hippocampal neurones. Among other ClC-3 functions that could be regulated by Ins(3,4,5,6)P4 are tumor cell migration [7], apoptosis [8], and inflammatory responses [9]. Ins(3,4,5,6)P4 is a ubiquitous cellular signal with diverse biological actions.
Collapse
Affiliation(s)
- Jennifer Mitchell
- Inositol Signaling Group, National Institute of Environmental Health Sciences, National Institutes of Health, U.S. Department of Health and Human Services, P.O. Box 12233, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | |
Collapse
|
39
|
Tao R, Lau CP, Tse HF, Li GR. Regulation of cell proliferation by intermediate-conductance Ca2+-activated potassium and volume-sensitive chloride channels in mouse mesenchymal stem cells. Am J Physiol Cell Physiol 2008; 295:C1409-16. [PMID: 18815226 DOI: 10.1152/ajpcell.00268.2008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bone marrow mesenchymal stem cells (MSCs) are a promising cell source for regenerative medicine; however, their cellular physiology is not fully understood. The present study aimed at exploring the potential roles of the two dominant functional ion channels, intermediate-conductance Ca(2+)-activated potassium (IK(Ca)) and volume-sensitive chloride (I(Cl.vol)) channels, in regulating proliferation of mouse MSCs. We found that inhibition of IK(Ca) with clotrimazole and I(Cl.vol) with 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB) reduced cell proliferation in a concentration-dependent manner. Knockdown of KCa3.1 or Clcn3 with specific short interference (si)RNAs significantly reduced IK(Ca) or I(Cl.vol) density and channel protein and produced a remarkable suppression of cell proliferation (by 24.4 +/- 9.6% and 29.5 +/- 7.2%, respectively, P < 0.05 vs. controls). Flow cytometry analysis showed that mouse MSCs retained at G(0)/G(1) phase (control: 51.65 +/- 3.43%) by inhibiting IK(Ca) or I(Cl.vol) using clotrimazole (2 microM: 64.45 +/- 2.20%, P < 0.05) or NPPB (200 microM: 82.89 +/- 2.49%, P < 0.05) or the specific siRNAs, meanwhile distribution of cells in S phase was decreased. Western blot analysis revealed a reduced expression of the cell cycle regulatory proteins cyclin D1 and cyclin E. Collectively, our results have demonstrated that IK(Ca) and I(Cl.vol) channels regulate cell cycle progression and proliferation of mouse MSCs by modulating cyclin D1 and cyclin E expression.
Collapse
Affiliation(s)
- Rong Tao
- Dept. of Medicine, L8-01, Laboratory Block, FMB, The Univ. of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong SAR China
| | | | | | | |
Collapse
|
40
|
Matsuda JJ, Filali MS, Volk KA, Collins MM, Moreland JG, Lamb FS. Overexpression of CLC-3 in HEK293T cells yields novel currents that are pH dependent. Am J Physiol Cell Physiol 2008; 294:C251-62. [DOI: 10.1152/ajpcell.00338.2007] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ClC-3 is a member of the ClC family of anion channels/transporters. Recently, the closely related proteins ClC-4 and ClC-5 were shown to be Cl−/H+antiporters ( 39 , 44 ). The function of ClC-3 has been controversial. We studied anion currents in HEK293T cells expressing wild-type or mutant ClC-3. The basic biophysical properties of ClC-3 currents were very similar to those of ClC-4 and ClC-5, and distinct from those of the swelling-activated anion channel. ClC-3 expression induced currents with time-dependent activation that rectified sharply in the outward direction. The reversal potential of the current shifted by −48.3 ± 2.5 mV per 10-fold (decade) change in extracellular Cl−concentration, which did not conform to the behavior of an anion-selective channel based upon the Nernst equation, which predicts a −58.4 mV/decade shift at 22°C. Manipulation of extracellular pH (6.35–8.2) altered reversal potential by 10.2 ± 3.0 mV/decade, suggesting that ClC-3 currents were coupled to proton movement. Mutation of a specific glutamate residue (E224A) changed voltage dependence in a manner similar to that observed in other ClC Cl−/H+antiporters. Mutant currents exhibited Nernstian changes in reversal potential in response to altered extracellular Cl−concentration that averaged −60 ± 3.4 mV/decade and were pH independent. Thus ClC-3 overexpression induced a pH-sensitive conductance in HEK293T cells that is biophysically similar to ClC-4 and ClC-5.
Collapse
|
41
|
Miller FJ, Filali M, Huss GJ, Stanic B, Chamseddine A, Barna TJ, Lamb FS. Cytokine activation of nuclear factor kappa B in vascular smooth muscle cells requires signaling endosomes containing Nox1 and ClC-3. Circ Res 2007; 101:663-71. [PMID: 17673675 DOI: 10.1161/circresaha.107.151076] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Reactive oxygen species (ROS) are mediators of intracellular signals for a myriad of normal and pathologic cellular events, including differentiation, hypertrophy, proliferation, and apoptosis. NADPH oxidases are important sources of ROS that are present in diverse tissues throughout the body and activate many redox-sensitive signal transduction and gene expression pathways. To avoid toxicity and provide specificity of signaling, ROS production and metabolism necessitate tight regulation that likely includes subcellular compartmentalization. However, the constituent elements of NADPH oxidase-dependent cell signaling are not known. To address this issue, we examined cytokine generation of ROS and subsequent activation of the transcription factor nuclear factor kappaB in vascular smooth muscle cells (SMCs). Tumor necrosis factor-alpha and interleukin (IL)-1beta stimulation of SMCs resulted in diphenylene iodonium-sensitive ROS production within intracellular vesicles. Nox1 and p22(phox), integral membrane subunits of NADPH oxidase, coimmunoprecipitated with early endosomal markers in SMCs. ClC-3, an anion transporter that is primarily found in intracellular vesicles, also colocalized with Nox1 in early endosomes and was necessary for tumor necrosis factor-alpha and interleukin-1beta generation of ROS. Cytokine activation of nuclear factor kappaB in SMCs required both Nox1 and ClC-3. We conclude that in response to tumor necrosis factor-alpha and interleukin-1beta, NADPH oxidase generates ROS within early endosomes and that Nox1 cannot produce sufficient ROS for cell signaling in the absence of ClC-3. These data best support a model whereby ClC-3 is required for charge neutralization of the electron flow generated by Nox1 across the membrane of signaling endosomes.
Collapse
MESH Headings
- Animals
- Cells, Cultured
- Chloride Channels/genetics
- Chloride Channels/physiology
- Cytokines/physiology
- Endosomes/genetics
- Endosomes/metabolism
- Endosomes/physiology
- Humans
- Mice
- Mice, Knockout
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/physiology
- NADPH Oxidase 1
- NADPH Oxidases/genetics
- NADPH Oxidases/physiology
- NF-kappa B/genetics
- NF-kappa B/metabolism
- Signal Transduction/physiology
Collapse
|
42
|
Sanhueza M, McIntyre CC, Lisman JE. Reversal of synaptic memory by Ca2+/calmodulin-dependent protein kinase II inhibitor. J Neurosci 2007; 27:5190-9. [PMID: 17494705 PMCID: PMC6672374 DOI: 10.1523/jneurosci.5049-06.2007] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Long-term potentiation (LTP) is an activity-dependent strengthening of synapses that is thought to underlie memory storage. Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been a leading candidate as a memory molecule because it is persistently activated after LTP induction and can enhance transmission. Furthermore, a mutation that blocks persistent activation blocks LTP and forms of learning. However, direct evidence for a role of the kinase in maintaining synaptic strength has been lacking. Here, we show that a newly developed noncompetitive inhibitor of CaMKII strongly reduces synaptic transmission in the CA1 region of the hippocampal slice. This occurs through both presynaptic and postsynaptic action. To study the role of CaMKII in the maintenance of LTP, inhibitor was applied after LTP induction and then removed. Inhibition occurred in both LTP and control pathways but only partially recovered. The nonrecovering component was attributable primarily to a postsynaptic change. To test whether nonrecovery was attributable to a persistent reversal of LTP, we first saturated LTP and then transiently applied inhibitor. This procedure allowed additional LTP to be induced, indicating a reversal of an LTP maintenance mechanism. This is the first procedure that can reverse LTP by chemical means and suggests that a component of synaptic memory is attributable to CaMKII. The procedure also enhanced the LTP that could be induced in the control pathway, consistent with the idea that CaMKII is involved in controlling basal synaptic strength, perhaps as a result of LTP that occurred in vivo.
Collapse
Affiliation(s)
- Magdalena Sanhueza
- Departamento de Biologia, Facultad de Ciencias, Universidad de Chile, Santiago 780-0024, Chile, and
| | - Charmian C. McIntyre
- Biology Department and Volen Center for Complex Systems–MS 008, Brandeis University, Waltham, Massachusetts 02454
| | - John E. Lisman
- Biology Department and Volen Center for Complex Systems–MS 008, Brandeis University, Waltham, Massachusetts 02454
| |
Collapse
|
43
|
McCloskey DT, Doherty L, Dai YP, Miller L, Hume JR, Yamboliev IA. Hypotonic activation of short ClC3 isoform is modulated by direct interaction between its cytosolic C-terminal tail and subcortical actin filaments. J Biol Chem 2007; 282:16871-7. [PMID: 17442672 DOI: 10.1074/jbc.m700379200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Short ClC3 isoform (sClC3) functions as a volume-sensitive outwardly rectifying anion channel (VSOAC) in some cell types. In previous studies, we have shown that the hypotonic activation of sClC3 is linked to cell swelling-mediated remodeling of the actin cytoskeleton. In the present study, we have tested the hypothesis that the cytosolic tails of sClC3 bind to actin directly and that binding modulates the hypotonic activation of the channel. Co-sedimentation assays in vitro demonstrated a strong binding between the glutathione S-transferase-fused cytosolic C terminus of sClC3 (GST-sClC3-CT) to filamentous actin (F-actin) but not to globular monomeric actin (G-actin). The GST-fused N terminus (GST-sClC3-NT) exhibited low binding affinity to both G- and F-actin. Co-sedimentation experiments with progressively truncated GST-sClC3-CT indicated that the F-actin binding region is located between amino acids 690 and 760 of sClC3. Two synthetic peptides mapping basic clusters of the cytosolic sClC3-CT (CTP2, isoleucine 716 to leucine 734; and CTP3, proline 688 to proline 709) prevented binding of GST-sClC3-CT to F-actin in vitro. Dialysis into NIH/3T3 cells of these two peptides (but not of synthetic peptide CTP1 (isoleucine 737 to glutamine 748)) reduced the maximal current density by 60 and 38%, respectively. Based on these results, we have concluded that, by direct interaction with subcortical actin filaments, sClC3 contributes to the hypotonic stress-induced VSOACs in NIH/3T3 cells.
Collapse
Affiliation(s)
- Diana T McCloskey
- Department of Pharmacology and Center of Biomedical Research Excellence, University of Nevada School of Medicine, Reno, Nevada 89557, USA
| | | | | | | | | | | |
Collapse
|
44
|
Zifarelli G, Pusch M. CLC chloride channels and transporters: a biophysical and physiological perspective. Rev Physiol Biochem Pharmacol 2007; 158:23-76. [PMID: 17729441 DOI: 10.1007/112_2006_0605] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Chloride-transporting proteins play fundamental roles in many tissues in the plasma membrane as well as in intracellular membranes. They have received increasing attention in the last years because crucial, and often unexpected and novel, physiological functions have been disclosed with gene-targeting approaches, X-ray crystallography, and biophysical analysis. CLC proteins form a gene family that comprises nine members in mammals, at least four of which are involved in human genetic diseases. The X-ray structure of the bacterial CLC homolog, ClC-ec1, revealed a complex fold and confirmed the anticipated homodimeric double-barreled architecture of CLC-proteins with two separate Cl-ion transport pathways, one in each subunit. Four of the mammalian CLC proteins, ClC-1, ClC-2, ClC-Ka, and ClC-Kb, are chloride ion channels that fulfill their functional roles-stabilization of the membrane potential, transepithelial salt transport, and ion homeostasisin the plasma membrane. The other five CLC proteins are predominantly expressed in intracellular organelles like endosomes and lysosomes, where they are probably important for a proper luminal acidification, in concert with the V-type H+-ATPase. Surprisingly, ClC-4, ClC-5, and probably also ClC-3, are not Cl- ion channels but exhibit significant Cl-/H+ antiporter activity, as does the bacterial homolog ClC-ec1 and the plant homolog AtCLCa. The physiological significance of the Cl-/H+ antiport activity remains to be established.
Collapse
Affiliation(s)
- G Zifarelli
- CNR, Istituto di Biofisica, Via De Marini 6, 16149 Genova, Italy
| | | |
Collapse
|
45
|
Wang XQ, Deriy LV, Foss S, Huang P, Lamb FS, Kaetzel MA, Bindokas V, Marks JD, Nelson DJ. CLC-3 Channels Modulate Excitatory Synaptic Transmission in Hippocampal Neurons. Neuron 2006; 52:321-33. [PMID: 17046694 DOI: 10.1016/j.neuron.2006.08.035] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 06/26/2006] [Accepted: 08/23/2006] [Indexed: 10/24/2022]
Abstract
It is well established that ligand-gated chloride flux across the plasma membrane modulates neuronal excitability. We find that a voltage-dependent Cl(-) conductance increases neuronal excitability in immature rodents as well, enhancing the time course of NMDA receptor-mediated miniature excitatory postsynaptic potentials (mEPSPs). This Cl(-) conductance is activated by CaMKII, is electrophysiologically identical to the CaMKII-activated CLC-3 conductance in nonneuronal cells, and is absent in clc-3(-/-) mice. Systematically decreasing [Cl(-)](i) to mimic postnatal [Cl(-)](i) regulation progressively decreases the amplitude and decay time constant of spontaneous mEPSPs. This Cl(-)-dependent change in synaptic strength is absent in clc-3(-/-) mice. Using surface biotinylation, immunohistochemistry, electron microscopy, and coimmunoprecipitation studies, we find that CLC-3 channels are localized on the plasma membrane, at postsynaptic sites, and in association with NMDA receptors. This is the first demonstration that a voltage-dependent chloride conductance modulates neuronal excitability. By increasing postsynaptic potentials in a Cl(-) dependent fashion, CLC-3 channels regulate neuronal excitability postsynaptically in immature neurons.
Collapse
Affiliation(s)
- Xue Qing Wang
- Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Shears SB. Can intervention in inositol phosphate signalling pathways improve therapy for cystic fibrosis? Expert Opin Ther Targets 2006; 9:1307-17. [PMID: 16300477 DOI: 10.1517/14728222.9.6.1307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Airway epithelial cells from cystic fibrosis (CF) individuals cannot secrete adequate Cl- through cystic fibrosis transmembrane regulator, and their Na+ channel (ENaC) activity is increased so that excessive Na+ and water is absorbed from the lumen. These aberrant transport activities can, at least partly, be compensated by pharmacologically increasing the activities of Ca2+-activated Cl- channels (CaCCs). The therapeutic value of this approach is currently being examined in clinical trials of candidate CF drugs such as INS-37217 (Inspire Pharmaceuticals) and Moli1901 (Lantibio, Inc.). This review argues that these drug development programmes will be helped if one can fully understand how the CaCCs are inhibited by inositol 3,4,5,6-tetrakisphosphate (Ins(3,4,5,6)P4), so that there can be pharmacological intervention in this process. Furthermore, genes that encode enzymes controlling Ins(3,4,5,6)P4 metabolism should be viewed as impacting upon CaCC activity; this, in turn, may influence the severity of the CF condition. Expression profiling of genes that regulate inositol phosphate metabolism may also illuminate variability in patient response to treatment regimens that target CaCCs. Compounds have been developed that can activate CaCCs by antagonising their inhibition by Ins(3,4,5,6)P4. One member of this drug family (INO-4995; Inologic) was recently shown to inhibit ENaC, thereby reducing fluid absorbtion by airway epithelial cells.
Collapse
Affiliation(s)
- Stephen B Shears
- Inositol Phosphate Signaling Group, NIEHS/NIH/DHHS, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
47
|
Guan YY, Wang GL, Zhou JG. The ClC-3 Cl− channel in cell volume regulation, proliferation and apoptosis in vascular smooth muscle cells. Trends Pharmacol Sci 2006; 27:290-6. [PMID: 16697056 DOI: 10.1016/j.tips.2006.04.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 03/09/2006] [Accepted: 04/19/2006] [Indexed: 01/23/2023]
Abstract
The volume-regulated Cl(-) current (I(Cl.vol)) is responsible for the transmembrane Cl(-) transport that is involved in cell volume regulatory mechanisms. Although the regulation of cell volume is a fundamental function of healthy cells for maintaining constant size, the molecular genetic identification of I(Cl.vol) is still being debated. Recent studies in vascular smooth muscle support the idea that ClC-3, a member of the voltage-gated ClC Cl(-) channel family, is the molecular component involved in the activation or regulation of I(Cl.vol). Moreover, gene-targeting studies in vascular smooth muscle cells (VSMCs) and other cell types indicate emerging roles of ClC-3 in cell proliferation and apoptosis. These findings indicate that ClC-3 might be involved in modulating vascular remodeling in hypertension and arteriosclerosis.
Collapse
Affiliation(s)
- Yong-Yuan Guan
- Department of Pharmacology, Zhongshan Medical College, Sun Yat-sen University, 74 Zhongshan 2 Road, Guangzhou 510089, China.
| | | | | |
Collapse
|
48
|
Rossow CF, Duan D, Hatton WJ, Britton F, Hume JR, Horowitz B. Functional role of amino terminus in ClC-3 chloride channel regulation by phosphorylation and cell volume. Acta Physiol (Oxf) 2006; 187:5-19. [PMID: 16734738 DOI: 10.1111/j.1748-1716.2006.01550.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM This study investigated the functional role of the ClC-3 amino-terminus in channel regulation in response to changes in cell volume. METHODS Wild-type sClC-3 tagged with a green fluorescence protein (GFP) at the C-terminus was used as a template to construct a number of deletion mutants which were functionally expressed in NIH-3T3 cells. Whole cell and single channel patch-clamp electrophysiology was used to determine the functional properties of heterologously expressed channels. RESULTS The first 100 amino acids of the ClC-3 N-terminus were removed and the truncated channel (sClC-3DeltaNT) was functionally expressed. Immunocytochemistry confirmed membrane expression of both wtsClC-3 and sClC-3DeltaNT channels in NIH/3T3 cells. sClC-3DeltaNT yielded constitutively active functional channels, which showed no response to protein kinase C or changes in cell volume. Deletion of a cluster of negatively charged amino acids 16-21 (sClC-3Delta16-21) within the N-terminus also yielded a constitutively active open channel phenotype, indicating these amino acids are involved in the N-type regulation. Intracellular delivery of a thiol-phosphorylated peptide corresponding to N-terminal residues 12-61 (NT peptide) markedly inhibited sClC-3DeltaNT whole-cell and single-channel currents, further confirming the essential role of the N-terminus in volume regulation of channel activity. CONCLUSIONS These data strongly suggest the N-terminus of sClC-3 channels acts as a blocking particle inhibiting the flow of anions through the channel pore. This 'N-type' regulation of sClC-3 channels may be an important transducing mechanism linking changes in cell volume and channel protein phosphorylation to channel gating.
Collapse
Affiliation(s)
- C F Rossow
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | | | | | | | | | | |
Collapse
|
49
|
Abstract
After exocytosis, synaptic vesicles are recycled locally in the synaptic terminal and are refilled with neurotransmitter via vesicular transporters. The biophysical mechanisms of refilling are poorly understood, but it is clear that the generation of a proton gradient across the vesicle membrane is crucial. To better understand the determinants of vesicle refilling, we developed a novel method to measure unambiguously the kinetics of synaptic vesicle reacidification at individual synaptic terminals. Hippocampal neurons transfected with synapto-pHluorin (SpH), a synaptic vesicle-targeted lumenal GFP (green fluorescent protein), whose fluorescence is quenched when protonated (pKa approximately 7.1), were rapidly surface-quenched immediately after trains of repetitive electrical stimulation. The recently endocytosed alkaline pool of SpH is protected from such surface quenching, and its fluorescence decay reflects reacidification kinetics. These measurements indicate that, after compensatory endocytosis, synaptic vesicles reacidify with first-order kinetics (tau approximately 4-5 s) and that their rate of reacidification is subject to slowing by increased external buffer.
Collapse
|
50
|
Welch NC, Lalonde MR, Barnes S, Kelly MEM. Calcium-activated chloride channels in müller cells acutely isolated from tiger salamander retina. Glia 2006; 53:74-80. [PMID: 16158415 DOI: 10.1002/glia.20270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ca(2+)-activated chloride channels were identified with whole-cell patch-clamp recording techniques in salamander retinal Müller cells. Cl(Ca) channels were activated by membrane depolarizations that elicited Ca2+ influx or the application of the Ca2+ ionophore, ionomycin. The Ca channel blocker, Cd2+, abolished the Cl(Ca) channel tail currents. Increasing the duration of the depolarizing pulse resulted in enhancement of the Cl(Ca) channel tail current. Repetitive depolarizations with rapid pulses to +20 mV produced a buildup of I(Cl(Ca)), which reversed at 0 mV in symmetrical [Cl-] and at -40 mV when intracellular [Cl-] was reduced to 10% of the external concentration. I(Cl(Ca)) was blocked by the Cl channel blocker niflumic acid, while niflumic acid had no effect on voltage-gated Ca channels. These results offer the first demonstration of Cl(Ca) channels in a nonastrocytic glial cell and expand our understanding of the functional capacities of retinal glial cells.
Collapse
Affiliation(s)
- Nicole C Welch
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | | | | |
Collapse
|