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Zhang Y, Wu K, Li Y, Wu S, Warshel A, Bai C. Predicting Mutational Effects on Ca 2+-Activated Chloride Conduction of TMEM16A Based on a Simulation Study. J Am Chem Soc 2024; 146:4665-4679. [PMID: 38319142 DOI: 10.1021/jacs.3c11940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
The dysfunction and defects of ion channels are associated with many human diseases, especially for loss-of-function mutations in ion channels such as cystic fibrosis transmembrane conductance regulator mutations in cystic fibrosis. Understanding ion channels is of great current importance for both medical and fundamental purposes. Such an understanding should include the ability to predict mutational effects and describe functional and mechanistic effects. In this work, we introduce an approach to predict mutational effects based on kinetic information (including reaction barriers and transition state locations) obtained by studying the working mechanism of target proteins. Specifically, we take the Ca2+-activated chloride channel TMEM16A as an example and utilize the computational biology model to predict the mutational effects of key residues. Encouragingly, we verified our predictions through electrophysiological experiments, demonstrating a 94% prediction accuracy regarding mutational directions. The mutational strength assessed by Pearson's correlation coefficient is -0.80 between our calculations and the experimental results. These findings suggest that the proposed methodology is reliable and can provide valuable guidance for revealing functional mechanisms and identifying key residues of the TMEM16A channel. The proposed approach can be extended to a broad scope of biophysical systems.
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Affiliation(s)
- Yue Zhang
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Kang Wu
- South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China
| | - Yuqing Li
- South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China
| | - Song Wu
- South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China
| | - Arieh Warshel
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Chen Bai
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
- Chenzhu Biotechnology Co., Ltd., Hangzhou 310005, China
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2
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Lu P, Lifshitz LM, Bellve K, ZhuGe R. TMEM16A in smooth muscle cells acts as a pacemaker channel in the internal anal sphincter. Commun Biol 2024; 7:151. [PMID: 38317010 PMCID: PMC10844222 DOI: 10.1038/s42003-024-05850-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/23/2024] [Indexed: 02/07/2024] Open
Abstract
Maintenance of fecal continence requires a continuous or basal tone of the internal anal sphincter (IAS). Paradoxically, the basal tone results largely from high-frequency rhythmic contractions of the IAS smooth muscle. However, the cellular and molecular mechanisms that initiate these contractions remain elusive. Here we show that the IAS contains multiple pacemakers. These pacemakers spontaneously generate propagating calcium waves that drive rhythmic contractions and establish the basal tone. These waves are myogenic and act independently of nerve, paracrine or autocrine signals. Using cell-specific gene knockout mice, we further found that TMEM16A Cl- channels in smooth muscle cells (but not in the interstitial cells of Cajal) are indispensable for pacemaking, rhythmic contractions, and basal tone. Our results identify TMEM16A in smooth muscle cells as a critical pacemaker channel that enables the IAS to contract rhythmically and continuously. This study provides cellular and molecular insights into fecal continence.
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Affiliation(s)
- Ping Lu
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Lawrence M Lifshitz
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Karl Bellve
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Ronghua ZhuGe
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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Sanders KM, Santana LF, Baker SA. Interstitial cells of Cajal - pacemakers of the gastrointestinal tract. J Physiol 2023. [PMID: 37997170 DOI: 10.1113/jp284745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/06/2023] [Indexed: 11/25/2023] Open
Abstract
Gastrointestinal (GI) organs display spontaneous, non-neurogenic electrical, and mechanical rhythmicity that underlies fundamental motility patterns, such as peristalsis and segmentation. Electrical rhythmicity (aka slow waves) results from pacemaker activity generated by interstitial cells of Cajal (ICC). ICC express a unique set of ionic conductances and Ca2+ handling mechanisms that generate and actively propagate slow waves. GI smooth muscle cells lack these conductances. Slow waves propagate actively within ICC networks and conduct electrotonically to smooth muscle cells via gap junctions. Slow waves depolarize smooth muscle cells and activate voltage-dependent Ca2+ channels (predominantly CaV1.2), causing Ca2+ influx and excitation-contraction coupling. The main conductances responsible for pacemaker activity in ICC are ANO1, a Ca2+ -activated Cl- conductance, and CaV3.2. The pacemaker cycle, as currently understood, begins with spontaneous, localized Ca2+ release events in ICC that activate spontaneous transient inward currents due to activation of ANO1 channels. Depolarization activates CaV 3.2 channels, causing the upstroke depolarization phase of slow waves. The upstroke is transient and followed by a long-duration plateau phase that can last for several seconds. The plateau phase results from Ca2+ -induced Ca2+ release and a temporal cluster of localized Ca2+ transients in ICC that sustains activation of ANO1 channels and clamps membrane potential near the equilibrium potential for Cl- ions. The plateau phase ends, and repolarization occurs, when Ca2+ stores are depleted, Ca2+ release ceases and ANO1 channels deactivate. This review summarizes key mechanisms responsible for electrical rhythmicity in gastrointestinal organs.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, USA
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, University of California, Davis, CA, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, USA
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Tu L, Bean JC, He Y, Liu H, Yu M, Liu H, Zhang N, Yin N, Han J, Scarcelli NA, Conde KM, Wang M, Li Y, Feng B, Gao P, Cai ZL, Fukuda M, Xue M, Tong Q, Yang Y, Liao L, Xu J, Wang C, He Y, Xu Y. Anoctamin 4 channel currents activate glucose-inhibited neurons in the mouse ventromedial hypothalamus during hypoglycemia. J Clin Invest 2023; 133:e163391. [PMID: 37261917 PMCID: PMC10348766 DOI: 10.1172/jci163391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 05/30/2023] [Indexed: 06/03/2023] Open
Abstract
Glucose is the basic fuel essential for maintenance of viability and functionality of all cells. However, some neurons - namely, glucose-inhibited (GI) neurons - paradoxically increase their firing activity in low-glucose conditions and decrease that activity in high-glucose conditions. The ionic mechanisms mediating electric responses of GI neurons to glucose fluctuations remain unclear. Here, we showed that currents mediated by the anoctamin 4 (Ano4) channel are only detected in GI neurons in the ventromedial hypothalamic nucleus (VMH) and are functionally required for their activation in response to low glucose. Genetic disruption of the Ano4 gene in VMH neurons reduced blood glucose and impaired counterregulatory responses during hypoglycemia in mice. Activation of VMHAno4 neurons increased food intake and blood glucose, while chronic inhibition of VMHAno4 neurons ameliorated hyperglycemia in a type 1 diabetic mouse model. Finally, we showed that VMHAno4 neurons represent a unique orexigenic VMH population and transmit a positive valence, while stimulation of neurons that do not express Ano4 in the VMH (VMHnon-Ano4) suppress feeding and transmit a negative valence. Together, our results indicate that the Ano4 channel and VMHAno4 neurons are potential therapeutic targets for human diseases with abnormal feeding behavior or glucose imbalance.
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Affiliation(s)
- Longlong Tu
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Jonathan C. Bean
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Yang He
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Hailan Liu
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Meng Yu
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Hesong Liu
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Nan Zhang
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Na Yin
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Junying Han
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Nikolas A. Scarcelli
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Kristine M. Conde
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Mengjie Wang
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Yongxiang Li
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Bing Feng
- Brain glycemic and metabolism control department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Peiyu Gao
- Brain glycemic and metabolism control department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Zhao-Lin Cai
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, USA
| | - Makoto Fukuda
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Mingshan Xue
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, USA
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Yongjie Yang
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Lan Liao
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Jianming Xu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Chunmei Wang
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Yanlin He
- Brain glycemic and metabolism control department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Yong Xu
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
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5
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Davis MJ, Earley S, Li YS, Chien S. Vascular mechanotransduction. Physiol Rev 2023; 103:1247-1421. [PMID: 36603156 PMCID: PMC9942936 DOI: 10.1152/physrev.00053.2021] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 09/26/2022] [Accepted: 10/04/2022] [Indexed: 01/07/2023] Open
Abstract
This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Scott Earley
- Department of Pharmacology, University of Nevada, Reno, Nevada
| | - Yi-Shuan Li
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
| | - Shu Chien
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
- Department of Medicine, University of California, San Diego, California
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6
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Dewdney B, Ursich L, Fletcher EV, Johns TG. Anoctamins and Calcium Signalling: An Obstacle to EGFR Targeted Therapy in Glioblastoma? Cancers (Basel) 2022; 14:cancers14235932. [PMID: 36497413 PMCID: PMC9740065 DOI: 10.3390/cancers14235932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 12/05/2022] Open
Abstract
Glioblastoma is the most common form of high-grade glioma in adults and has a poor survival rate with very limited treatment options. There have been no significant advancements in glioblastoma treatment in over 30 years. Epidermal growth factor receptor is upregulated in most glioblastoma tumours and, therefore, has been a drug target in recent targeted therapy clinical trials. However, while many inhibitors and antibodies for epidermal growth factor receptor have demonstrated promising anti-tumour effects in preclinical models, they have failed to improve outcomes for glioblastoma patients in clinical trials. This is likely due to the highly plastic nature of glioblastoma tumours, which results in therapeutic resistance. Ion channels are instrumental in the development of many cancers and may regulate cellular plasticity in glioblastoma. This review will explore the potential involvement of a class of calcium-activated chloride channels called anoctamins in brain cancer. We will also discuss the integrated role of calcium channels and anoctamins in regulating calcium-mediated signalling pathways, such as epidermal growth factor signalling, to promote brain cancer cell growth and migration.
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Affiliation(s)
- Brittany Dewdney
- Cancer Centre, Telethon Kids Institute, Perth, WA 6009, Australia
- Centre for Child Health Research, University of Western Australia, Perth, WA 6009, Australia
- Correspondence: ; Tel.: +61-8-6319-1023
| | - Lauren Ursich
- Cancer Centre, Telethon Kids Institute, Perth, WA 6009, Australia
- School of Biomedical Sciences, University of Western Australia, Perth, WA 6009, Australia
| | - Emily V. Fletcher
- Cancer Centre, Telethon Kids Institute, Perth, WA 6009, Australia
- Centre for Child Health Research, University of Western Australia, Perth, WA 6009, Australia
| | - Terrance G. Johns
- Cancer Centre, Telethon Kids Institute, Perth, WA 6009, Australia
- Centre for Child Health Research, University of Western Australia, Perth, WA 6009, Australia
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Grainger N, Shonnard CC, Quiggle SK, Fox EB, Presley H, Daugherty R, Shonnard MC, Drumm BT, Sanders KM. Propagation of Pacemaker Activity and Peristaltic Contractions in the Mouse Renal Pelvis Rely on Ca 2+-activated Cl - Channels and T-Type Ca 2+ Channels. FUNCTION (OXFORD, ENGLAND) 2022; 3:zqac041. [PMID: 36325511 PMCID: PMC9614935 DOI: 10.1093/function/zqac041] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 01/07/2023]
Abstract
The process of urine removal from the kidney occurs via the renal pelvis (RP). The RP demarcates the beginning of the upper urinary tract and is endowed with smooth muscle cells. Along the RP, organized contraction of smooth muscle cells generates the force required to move urine boluses toward the ureters and bladder. This process is mediated by specialized pacemaker cells that are highly expressed in the proximal RP that generate spontaneous rhythmic electrical activity to drive smooth muscle depolarization. The mechanisms by which peristaltic contractions propagate from the proximal to distal RP are not fully understood. In this study, we utilized a transgenic mouse that expresses the genetically encoded Ca2+ indicator, GCaMP3, under a myosin heavy chain promotor to visualize spreading peristaltic contractions in high spatial detail. Using this approach, we discovered variable effects of L-type Ca2+ channel antagonists on contraction parameters. Inhibition of T-type Ca2+ channels reduced the frequency and propagation distance of contractions. Similarly, antagonizing Ca2+-activated Cl- channels or altering the transmembrane Cl- gradient decreased contractile frequency and significantly inhibited peristaltic propagation. These data suggest that voltage-gated Ca2+ channels are important determinants of contraction initiation and maintain the fidelity of peristalsis as the spreading contraction moves further toward the ureter. Recruitment of Ca2+-activated Cl- channels, likely Anoctamin-1, and T-type Ca2+ channels are required for efficiently conducting the depolarizing current throughout the length of the RP. These mechanisms are necessary for the efficient removal of urine from the kidney.
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Affiliation(s)
| | - Cameron C Shonnard
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Sage K Quiggle
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Emily B Fox
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Hannah Presley
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Robbie Daugherty
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Matthew C Shonnard
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA,Department of Life and Health Science, Dundalk Institute of Technology, Dublin Road, Dundalk, Co. Louth, A91 K584, Ireland
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
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Li C, Shi S, Gao D, Li B, Song G, Chen Y, An H, Xing C. Near-Infrared Light-Responsive Nanoinhibitors for Tumor Suppression through Targeting and Regulating Anion Channels. ACS APPLIED MATERIALS & INTERFACES 2022; 14:31715-31726. [PMID: 35798541 DOI: 10.1021/acsami.2c08503] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The gated state of anion channels is involved in the regulation of proliferation and migration of tumors. Specific regulators are urgently needed for efficacious cancer ablation. For this purpose, it is essential to understand the molecular mechanisms of interaction between the regulators and anion channels and apply this knowledge to regulate anion channels. Transmembrane 16A (TMEM16A) is the molecular basis of the calcium-activated chloride channels. It is an anion channel activated by Ca2+, and the inhibition of TMEM16A is associated with a decrease in tumorigenesis. Herein, we characterized a natural compound procyanidin (PC) as an efficacious and selective inhibitor of TMEM16A with an IC50 of 10.6 ± 0.6 μM. Our research revealed the precise sites (D383, R535, and E624) of electrostatic interactions between PC and TMEM16A. Near-infrared (NIR)-light-responsive photothermal conjugated polymer nanoparticles encapsulating PC (CPNs-PC) were established to remotely target and regulate the TMEM16A anion channel. Upon NIR irradiation, CPNs-PC downregulated the signaling pathway downstream of TMEM16A and arrested the cell cycle progression of cancer cells and improved the bioavailability of PC. The tumor inhibition ratio of CPNs-PC was superior to PC by 13.4%. Our findings enabled the development of a strategy to accurately and remotely regulate anion channels to promote tumor regression using NIR-light-responsive conjugated polymer nanoparticles containing specific inhibitors of TMEM16A.
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Affiliation(s)
- Chaoqun Li
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Sai Shi
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin 300071, P. R. China
| | - Dong Gao
- School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Boying Li
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Guoqiang Song
- School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Yafei Chen
- School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Hailong An
- School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Chengfen Xing
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
- School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
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9
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Drumm BT, Cobine CA, Baker SA. Insights on gastrointestinal motility through the use of optogenetic sensors and actuators. J Physiol 2022; 600:3031-3052. [PMID: 35596741 DOI: 10.1113/jp281930] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/13/2022] [Indexed: 11/08/2022] Open
Abstract
The muscularis of the gastrointestinal (GI) tract consists of smooth muscle cells (SMCs) and various populations of interstitial cells of Cajal (ICC), platelet-derived growth factor receptor α+ (PDGFRα+ ) cells, as well as excitatory and inhibitory enteric motor nerves. SMCs, ICC and PDGFRα+ cells form an electrically coupled syncytium, which together with inputs from the enteric nervous system (ENS) regulate GI motility. Early studies evaluating Ca2+ signalling behaviours in the GI tract relied upon indiscriminate loading of tissues with Ca2+ dyes. These methods lacked the means to study activity in specific cells of interest without encountering contamination from other cells within the preparation. Development of mice expressing optogenetic sensors (GCaMP, RCaMP) has allowed visualization of Ca2+ signalling behaviours in a cell specific manner. Additionally, availability of mice expressing optogenetic modulators (channelrhodopsins or halorhodospins) has allowed manipulation of specific signalling pathways using light. GCaMP expressing animals have been used to characterize Ca2+ signalling behaviours of distinct classes of ICC and SMCs throughout the GI musculature. These findings illustrate how Ca2+ signalling in ICC is fundamental in GI muscles, contributing to tone in sphincters, pacemaker activity in rhythmic muscles and relaying enteric signals to SMCs. Animals that express channelrhodopsin in specific neuronal populations have been used to map neural circuitry and to examine post junctional neural effects on GI motility. Thus, optogenetic approaches provide a novel means to examine the contribution of specific cell types to the regulation of motility patterns within complex multi-cellular systems. Abstract Figure Legends Optogenetic activators and sensors can be used to investigate the complex multi-cellular nature of the gastrointestinal (GI tract). Optogenetic activators that are activated by light such as channelrhodopsins (ChR2), OptoXR and halorhodopsinss (HR) proteins can be genetically encoded into specific cell types. This can be used to directly activate or silence specific GI cells such as various classes of enteric neurons, smooth muscle cells (SMC) or interstitial cells, such as interstitial cells of Cajal (ICC). Optogenetic sensors that are activated by different wavelengths of light such as green calmodulin fusion protein (GCaMP) and red CaMP (RCaMP) make high resolution of sub-cellular Ca2+ signalling possible within intact tissues of specific cell types. These tools can provide unparalleled insight into mechanisms underlying GI motility and innervation. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Department of Life & Health Science, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.,Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Caroline A Cobine
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Salah A Baker
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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10
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Straface M, Koussai MA, Makwana R, Crawley E, Palmer A, Cai W, Gharibans A, Adebibe M, Loy J, O’Grady G, Andrews PLR, Sanger GJ. A multi-parameter approach to measurement of spontaneous myogenic contractions in human stomach: Utilization to assess potential modulators of myogenic contractions. Pharmacol Res 2022; 180:106247. [DOI: 10.1016/j.phrs.2022.106247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/22/2022] [Accepted: 05/03/2022] [Indexed: 10/18/2022]
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11
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Shi S, Pang C, Ren S, Sun F, Ma B, Guo S, Li J, Chen Y, An H. Molecular dynamics simulation of TMEM16A channel: Linking structure with gating. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183777. [PMID: 34537214 DOI: 10.1016/j.bbamem.2021.183777] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 08/23/2021] [Accepted: 09/12/2021] [Indexed: 10/20/2022]
Abstract
TMEM16A, the calcium-activated chloride channel, is broadly expressed and plays pivotal roles in diverse physiological processes. To understand the structural and functional relationships of TMEM16A, it is necessary to fully clarify the structural basis of the gating of the TMEM16A channel. Herein, we performed the protein electrostatic analysis and molecular dynamics simulation on the TMEM16A in the presence and absence of Ca2+. Data showed that the separation of TM4 and TM6 causes pore expansion, and Q646 may be a key residue for the formation of π-helix in the middle segment of TM6. Moreover, E705 was found to form a group of H-bond interactions with D554/K588/K645 below the hydrophobic gate to stabilize the closed conformation of the pore in the Ca2+-free state. Interestingly, in the Ca2+ bound state, the E705 side chain swings 100o to serve as Ca2+-binding coordination and released K645. K645 is closer to the hydrophobic gate in the calcium-bound state, which facilitates the provision of electrostatic forces for chloride ions as the ions pass through the hydrophobic gate. Our findings provide the structural-based insights to understanding the mechanisms of gating of TMEM16A.
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Affiliation(s)
- Sai Shi
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China; Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China; Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Shuxi Ren
- Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Fude Sun
- Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Biao Ma
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China; Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China; Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Shuai Guo
- College of Life Science, Hebei University, Baoding 071002, Hebei, China
| | - Junwei Li
- Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Yafei Chen
- Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China
| | - Hailong An
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China; Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China; Key Laboratory of Molecular Biophysics of Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin 300401, China.
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12
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Otsuka Y, Bai X, Tanaka Y, Ihara E, Chinen T, Ogino H, Ogawa Y. Involvement of interstitial cells of Cajal in nicotinic acetylcholine receptor-induced relaxation of the porcine lower esophageal sphincter. Eur J Pharmacol 2021; 910:174491. [PMID: 34506779 DOI: 10.1016/j.ejphar.2021.174491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 08/27/2021] [Accepted: 09/03/2021] [Indexed: 11/15/2022]
Abstract
The interstitial cells of Cajal (ICCs) play an important role in coordinated gastrointestinal motility. The present study aimed to elucidate whether or how ICCs are involved in the lower esophageal sphincter (LES) relaxation induced by stimulation of the nicotinic acetylcholine receptor. The application of 1,1-dimethyl-4-phenyl-piperazinium (DMPP; a nicotinic acetylcholine receptor agonist) induced a transient relaxation in the circular smooth muscle of the porcine LES. DMPP-induced relaxation was abolished by not only 1 μM tetrodotoxin but also the inhibition of ICC activity by pretreatment with 100 μM carbenoxolone (a gap junction inhibitor), pretreatment with 100 μM CaCCinh-A01 (an anoctamin-1 blocker acting as a calcium-activated chloride channel inhibitor), and pretreatment with Cl--free solution. However, pretreatment with 100 μM Nω-nitro-L-arginine methyl ester had little effect on DMPP-induced relaxation. Furthermore, DMPP-induced relaxation was inhibited by pretreatment with 1 mM suramin, a purinergic P2 receptor antagonist, but not by 1 μM VIP (6-28), a vasoactive intestinal peptide (VIP) receptor antagonist. Stimulation of the purinergic P2 receptor with adenosine triphosphate (ATP) induced relaxation, which was abolished by the inhibition of ICC activity by pretreatment with CaCCinh-A01. In conclusion, membrane hyperpolarization of the ICCs via the activation of anoctamin-1 plays a central role in DMPP-induced relaxation. ATP may be a neurotransmitter for inhibitory enteric neurons, which stimulate the ICCs. The ICCs act as the interface of neurotransmission of nicotinic acetylcholine receptor in order to induce LES relaxation.
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Affiliation(s)
- Yoshihiro Otsuka
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Xiaopeng Bai
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Yoshimasa Tanaka
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Eikichi Ihara
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan; Department of Gastroenterology and Metabolism, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
| | - Takatoshi Chinen
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Haruei Ogino
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Yoshihiro Ogawa
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
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13
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Cai W, Makwana R, Straface M, Gharibans A, Andrews PLR, Sanger GJ. Evidence for tetrodotoxin-resistant spontaneous myogenic contractions of mouse isolated stomach that are dependent on acetylcholine. Br J Pharmacol 2021; 179:1187-1200. [PMID: 34519057 PMCID: PMC9297954 DOI: 10.1111/bph.15685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 12/24/2022] Open
Abstract
Background and Purpose Gastric pacemaker cells, interstitial cells of Cajal (ICC), are believed to initiate myogenic (non‐neuronal) contractions. These become damaged in gastroparesis, associated with dysrhythmic electrical activity and nausea. We utilised mouse isolated stomach to model myogenic contractions and investigate their origin and actions of interstitial cells of Cajal modulators. Experimental Approach Intraluminal pressure was recorded following distension with a physiological volume; tone, contraction amplitude and frequency were quantified. Compounds were bath applied. Key Results The stomach exhibited regular large amplitude contractions (median amplitude 9.0 [4.7–14.8] cmH2O, frequency 2.9 [2.5–3.4] c.p.m; n = 20), appearing to progress aborally. Tetrodotoxin (TTX, 10−6 M) had no effect on tone, frequency or amplitude but blocked responses to nerve stimulation. ω‐conotoxin GVIA (10−7 M) ± TTX was without effect on baseline motility. In the presence of TTX, (1) atropine (10−10–10−6 M) reduced contraction amplitude and frequency in a concentration‐related manner (pIC50 7.5 ± 0.3 M for amplitude), (2) CaCC channel (previously ANO1) inhibitors MONNA and CaCCinh‐A01 reduced contraction amplitude (significant at 10−5, 10−4 M respectively) and frequency (significant at 10−5 M), and (3), neostigmine (10−5 M) evoked a large, variable, increase in contraction amplitude, reduced by atropine (10−8–10−6 M) but unaffected (exploratory study) by the H1 receptor antagonist mepyramine (10−6 M). Conclusions and Implications The distended mouse stomach exhibited myogenic contractions, resistant to blockade of neural activity by TTX. In the presence of TTX, these contractions were prevented or reduced by compounds blocking interstitial cells of Cajal activity or by atropine and enhanced by neostigmine (antagonised by atropine), suggesting involvement of non‐neuronal ACh in their regulation.
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Affiliation(s)
- Weigang Cai
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Raj Makwana
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Marilisa Straface
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Armen Gharibans
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Paul L R Andrews
- Division of Biomedical Sciences, St George's University of London, London, UK
| | - Gareth J Sanger
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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14
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Liu Y, Liu Z, Wang K. The Ca 2+-activated chloride channel ANO1/TMEM16A: An emerging therapeutic target for epithelium-originated diseases? Acta Pharm Sin B 2021; 11:1412-1433. [PMID: 34221860 PMCID: PMC8245819 DOI: 10.1016/j.apsb.2020.12.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/19/2020] [Accepted: 09/14/2020] [Indexed: 02/07/2023] Open
Abstract
Anoctamin 1 (ANO1) or TMEM16A gene encodes a member of Ca2+ activated Cl– channels (CaCCs) that are critical for physiological functions, such as epithelial secretion, smooth muscle contraction and sensory signal transduction. The attraction and interest in ANO1/TMEM16A arise from a decade long investigations that abnormal expression or dysfunction of ANO1 is involved in many pathological phenotypes and diseases, including asthma, neuropathic pain, hypertension and cancer. However, the lack of specific modulators of ANO1 has impeded the efforts to validate ANO1 as a therapeutic target. This review focuses on the recent progress made in understanding of the pathophysiological functions of CaCC ANO1 and the current modulators used as pharmacological tools, hopefully illustrating a broad spectrum of ANO1 channelopathy and a path forward for this target validation.
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Key Words
- ANO1
- ANO1, anoctamin-1
- ASM, airway smooth muscle
- Ang II, angiotensin II
- BBB, blood–brain barrier
- CAMK, Ca2+/calmodulin-dependent protein kinase
- CF, cystic fibrosis
- CFTR, cystic fibrosis transmembrane conductance regulator
- Ca2+-activated Cl– channels (CaCCs)
- CaCCinh-A01
- CaCCs, Ca2+ activated chloride channels
- Cancer
- Cystic fibrosis
- DRG, dorsal root ganglion
- Drug target
- EGFR, epidermal growth factor receptor
- ENaC, epithelial sodium channels
- ER, endoplasmic reticulum
- ESCC, esophageal squamous cell carcinoma
- FRT, fisher rat thyroid
- GI, gastrointestinal
- GIST, gastrointestinal stromal tumor
- GPCR, G-protein coupled receptor
- HNSCC, head and neck squamous cell carcinoma
- HTS, high-throughput screening
- ICC, interstitial cells of Cajal
- IPAH, idiopathic pulmonary arterial hypertension
- MAPK, mitogen-activated protein kinase
- NF-κB, nuclear factor κB
- PAH, pulmonary arterial hypertension
- PAR2, protease activated receptor 2
- PASMC, pulmonary artery smooth muscle cells
- PIP2, phosphatidylinositol 4,5-bisphosphate
- PKD, polycystic kidney disease
- T16Ainh-A01
- TGF-β, transforming growth factor-β
- TMEM16A
- VGCC, voltage gated calcium channel
- VRAC, volume regulated anion channel
- VSMC, vascular smooth muscle cells
- YFP, yellow fluorescent protein
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Affiliation(s)
- Yani Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao 266073, China
- Institute of Innovative Drugs, Qingdao University, Qingdao 266021, China
| | - Zongtao Liu
- Department of Clinical Laboratory, Qingdao Third People's Hospital, Qingdao 266041, China
| | - KeWei Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao 266073, China
- Institute of Innovative Drugs, Qingdao University, Qingdao 266021, China
- Corresponding authors.
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15
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Lee JY, Zheng H, Sanders KM, Koh SD. Low-voltage-activated inward current in murine antral smooth muscle cells is an artifact. Am J Physiol Cell Physiol 2021; 320:C966-C973. [PMID: 33788632 DOI: 10.1152/ajpcell.00031.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two types of voltage-dependent inward currents were evoked by depolarization in murine antral smooth muscle cells (SMCs) bathed in Ca2+-containing physiological solution: high-voltage-activated (HVA) and low-voltage-activated (LVA) inward currents. We examined whether the LVA current was due to: 1) T-type Ca2+ channels, 2) Ca2+-activated Cl-channels, 3) nonselective cation channels (NSCC), or 4) voltage-dependent K+ channels. Replacement of external Ca2+ (2 mM) with equimolar Ba2+ increased the amplitude of the HVA current but blocked the LVA current. Nicardipine blocked the HVA current, and in the presence of nicardipine, T-type Ca2+ blockers failed to block LVA current. A Cl- channel antagonist had little effect on LVA current. Cation-free external solution completely abolished both HVA and LVA currents. Addition of Ca2+ to the solution restored only HVA currents. Addition of K+ (5 mM) to otherwise cation-free solution induced LVA current that reversed at -20 mV. These data suggest that LVA current is not due to T-type Ca2+ channels, Ca2+-activated Cl- channels, or NSCC. A-type K+ (KA) currents and delayed rectifying K+ (KDR) currents can be resolved in antral SMCs dialyzed with a solution containing 140 mM K+. When cells were exposed to high K+ external solution and dialyzed with Cs+-rich solution in the presence of nicardipine, LVA current was evoked and reversed at positive potentials. LVA currents were blocked by K+ channel blockers, 4-aminopyridine, and tetraethylammonium. In conclusion, LVA inward currents can be generated by K+ influx via KA channels in murine antral SMCs when cells were dialyzed with Cs+-rich solution.
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Affiliation(s)
- Ji Yeon Lee
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Haifeng Zheng
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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16
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Grigoriev VV. [Calcium-activated chloride channels: structure, properties, role in physiological and pathological processes]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2021; 67:17-33. [PMID: 33645519 DOI: 10.18097/pbmc20216701017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ca2+-activated chloride channels (CaCC) are a class of intracellular calcium activated chloride channels that mediate numerous physiological functions. In 2008, the molecular structure of CaCC was determined. CaCC are formed by the protein known as anoctamine 1 (ANO1 or TMEM16A). CaCC mediates the secretion of Cl- in secretory epithelia, such as the airways, salivary glands, intestines, renal tubules, and sweat glands. The presence of CaCC has also been recognized in the vascular muscles, smooth muscles of the respiratory tract, which control vascular tone and hypersensitivity of the respiratory tract. TMEM16A is activated in many cancers; it is believed that TMEM16A is involved in carcinogenesis. TMEM16A is also involved in cancer cells proliferation. The role of TMEM16A in the mechanisms of hypertension, asthma, cystic fibrosis, nociception, and dysfunction of the gastrointestinal tract has been determined. In addition to TMEM16A, its isoforms are involved in other physiological and pathophysiological processes. TMEM16B (or ANO2) is involved in the sense of smell, while ANO6 works like scramblase, and its mutation causes a rare bleeding disorder, known as Scott syndrome. ANO5 is associated with muscle and bone diseases. TMEM16A interacts with various cellular signaling pathways including: epidermal growth factor receptor (EGFR), mitogen-activated protein kinases (MAPK), calmodulin (CaM) kinases, transforming growth factor TGF-β. The review summarizes existing information on known natural and synthetic compounds that can block/modulate CaCC currents and their effect on some pathologies in which CaCC is involved.
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Affiliation(s)
- V V Grigoriev
- Institute of Physiologically Active Compounds of the Russian Academy of Sciences, Moscow, Russia
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17
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Drumm BT, Thornbury KD, Hollywood MA, Sergeant GP. Role of Ano1 Ca 2+-activated Cl - channels in generating urethral tone. Am J Physiol Renal Physiol 2021; 320:F525-F536. [PMID: 33554780 DOI: 10.1152/ajprenal.00520.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Urinary continence is maintained in the lower urinary tract by the contracture of urethral sphincters, including smooth muscle of the internal urethral sphincter. These contractions occlude the urethral lumen, preventing urine leakage from the bladder to the exterior. Over the past 20 years, research on the ionic conductances that contribute to urethral smooth muscle contractility has greatly accelerated. A debate has emerged over the role of interstitial cell of Cajal (ICC)-like cells in the urethra and their expression of Ca2+-activated Cl- channels encoded by anoctamin-1 [Ano1; transmembrane member 16 A (Tmem16a) gene]. It has been proposed that Ano1 channels expressed in urethral ICC serve as a source of depolarization for smooth muscle cells, increasing their excitability and contributing to tone. Although a clear role for Ano1 channels expressed in ICC is evident in other smooth muscle organs, such as the gastrointestinal tract, the role of these channels in the urethra is unclear, owing to differences in the species (rabbit, rat, guinea pig, sheep, and mouse) examined and experimental approaches by different groups. The importance of clarifying this situation is evident as effective targeting of Ano1 channels may lead to new treatments for urinary incontinence. In this review, we summarize the key findings from different species on the role of ICC and Ano1 channels in urethral contractility. Finally, we outline proposals for clarifying this controversial and important topic by addressing how cell-specific optogenetic and inducible cell-specific genetic deletion strategies coupled with advances in Ano1 channel pharmacology may clarify this area in future studies.NEW & NOTEWORTHY Studies from the rabbit have shown that anoctamin-1 (Ano1) channels expressed in urethral interstitial cells of Cajal (ICC) serve as a source of depolarization for smooth muscle cells, increasing excitability and tone. However, the role of urethral Ano1 channels is unclear, owing to differences in the species examined and experimental approaches. We summarize findings from different species on the role of urethral ICC and Ano1 channels in urethral contractility and outline proposals for clarifying this topic using cell-specific optogenetic approaches.
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Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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18
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Kim M, Lee SW, Kim J, Shin Y, Chang F, Kim JM, Cong X, Yu GY, Park K. LPS-induced epithelial barrier disruption via hyperactivation of CACC and ENaC. Am J Physiol Cell Physiol 2021; 320:C448-C461. [PMID: 33471620 DOI: 10.1152/ajpcell.00295.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Gram-negative bacterial lipopolysaccharide (LPS) increases the susceptibility of cells to pathogenic diseases, including inflammatory diseases and septic syndrome. In our experiments, we examined whether LPS induces epithelial barrier disruption in secretory epithelia and further investigated its underlying mechanism. The activities of Ca2+-activated Cl- channels (CACC) and epithelial Na+ channels (ENaC) were monitored with a short-circuit current using an Ussing chamber. Epithelial membrane integrity was estimated via transepithelial electrical resistance and paracellular permeability assays. We found that the apical application of LPS evoked short-circuit current (Isc) through the activation of CACC and ENaC. Although LPS disrupted epithelial barrier integrity, this was restored with the inhibition of CACC and ENaC, indicating the role of CACC and ENaC in the regulation of paracellular pathways. We confirmed that LPS, CACC, or ENaC activation evoked apical membrane depolarization. The exposure to a high-K+ buffer increased paracellular permeability. LPS induced the rapid redistribution of zonula occludens-1 (ZO-1) and reduced the expression levels of ZO-1 in tight junctions through apical membrane depolarization and tyrosine phosphorylation. However, the LPS-induced epithelial barrier disruption and degradation of ZO-1 were largely recovered by blocking CACC and ENaC. Furthermore, although LPS-impaired epithelial barrier became vulnerable to secondary bacterial infections, this vulnerability was prevented by inhibiting CACC and ENaC. We concluded that LPS induces the disruption of epithelial barrier integrity through the activation of CACC and ENaC, resulting in apical membrane depolarization and the subsequent tyrosine phosphorylation of ZO-1.
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Affiliation(s)
- Minkyoung Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
| | - Sang-Woo Lee
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
| | - Junchul Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
| | - Yonghwan Shin
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
| | - Fengjiao Chang
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
| | - Jin Man Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
| | - Xin Cong
- Department of Physiology and Pathophysiology, Peking University School and Hospital of Stomatology, Beijing, China
| | - Guang-Yan Yu
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China
| | - Kyungpyo Park
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, South Korea
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19
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Gasparotto D, Sbaraglia M, Rossi S, Baldazzi D, Brenca M, Mondello A, Nardi F, Racanelli D, Cacciatore M, Paolo Dei Tos A, Maestro R. Tumor genotype, location, and malignant potential shape the immunogenicity of primary untreated gastrointestinal stromal tumors. JCI Insight 2020; 5:142560. [PMID: 33048845 PMCID: PMC7710278 DOI: 10.1172/jci.insight.142560] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/07/2020] [Indexed: 12/13/2022] Open
Abstract
Intratumoral immune infiltrate was recently reported in gastrointestinal stromal tumors (GISTs). However, the tumor-intrinsic factors that dictate GIST immunogenicity are still largely undefined. To shed light on this issue, a large cohort (82 samples) of primary untreated GISTs, representative of major clinicopathological variables, was investigated by an integrated immunohistochemical, transcriptomic, and computational approach. Our results indicate that tumor genotype, location, and malignant potential concur to shape the immunogenicity of primary naive GISTs. Immune infiltration was greater in overt GISTs compared with that in lesions with limited malignant potential (miniGISTs), in KIT/PDGFRA-mutated tumors compared with that in KIT/PDGFRA WT tumors, and in PDGFRA-mutated compared with KIT-mutated GISTs. Within the KIT-mutated subset, a higher degree of immune colonization was detected in the intestine. Immune hot tumors showed expression patterns compatible with a potentially proficient but curbed antigen-specific immunity, hinting at sensitivity to immunomodulatory treatments. Poorly infiltrated GISTs, primarily KIT/PDGFRA WT intestinal tumors, showed activation of Hedgehog and WNT/β-catenin immune excluding pathways. This finding discloses a potential therapeutic vulnerability, as the targeting of these pathways might prove effective by both inhibiting pro-oncogenic signals and fostering antitumor immune responses. Finally, an intriguing anticorrelation between immune infiltration and ANO1/DOG1 expression was observed, suggesting an immunomodulatory activity for anoctamin-1.
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Affiliation(s)
- Daniela Gasparotto
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
| | - Marta Sbaraglia
- Department of Pathology, Azienda Ospedaliera Universitaria di Padova, Padua, Italy
| | - Sabrina Rossi
- Department of Pathology and Molecular Genetics, Treviso General Hospital, Treviso, Italy
| | - Davide Baldazzi
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
| | - Monica Brenca
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
| | - Alessia Mondello
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
| | - Federica Nardi
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
| | - Dominga Racanelli
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
| | - Matilde Cacciatore
- Department of Pathology and Molecular Genetics, Treviso General Hospital, Treviso, Italy
| | - Angelo Paolo Dei Tos
- Department of Pathology, Azienda Ospedaliera Universitaria di Padova, Padua, Italy
- Department of Medicine, University of Padua School of Medicine, Padua, Italy
| | - Roberta Maestro
- Unit of Oncogenetics and Functional Oncogenomics, Centro di Riferimento Oncologico di Aviano (CRO Aviano) IRCCS, National Cancer Institute, Aviano, Italy
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20
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Shan W, Hu Y, Ding J, Yang X, Lou J, Du Q, Liao Q, Luo L, Xu J, Xie R. Advances in Ca 2+ modulation of gastrointestinal anion secretion and its dysregulation in digestive disorders (Review). Exp Ther Med 2020; 20:8. [PMID: 32934673 PMCID: PMC7471861 DOI: 10.3892/etm.2020.9136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/22/2020] [Indexed: 11/29/2022] Open
Abstract
Intracellular calcium (Ca2+) is a critical cell signaling component in gastrointestinal (GI) physiology. Cytosolic calcium ([Ca2+]cyt), as a secondary messenger, controls GI epithelial fluid and ion transport, mucus and neuropeptide secretion, as well as synaptic transmission and motility. The key roles of Ca2+ signaling in other types of secretory cell (including those in the airways and salivary glands) are well known. However, its action in GI epithelial secretion and the underlying molecular mechanisms have remained to be fully elucidated. The present review focused on the role of [Ca2+]cyt in GI epithelial anion secretion. Ca2+ signaling regulates the activities of ion channels and transporters involved in GI epithelial ion and fluid transport, including Cl- channels, Ca2+-activated K+ channels, cystic fibrosis (CF) transmembrane conductance regulator and anion/HCO3- exchangers. Previous studies by the current researchers have focused on this field over several years, providing solid evidence that Ca2+ signaling has an important role in the regulation of GI epithelial anion secretion and uncovering underlying molecular mechanisms. The present review is largely based on previous studies by the current researchers and provides an overview of the currently known molecular mechanisms of GI epithelial anion secretion with an emphasis on Ca2+-mediated ion secretion and its dysregulation in GI disorders. In addition, previous studies by the current researchers demonstrated that different regulatory mechanisms are in place for GI epithelial HCO3- and Cl- secretion. An increased understanding of the roles of Ca2+ signaling and its targets in GI anion secretion may lead to the development of novel strategies to inhibit GI diseases, including the enhancement of fluid secretion in CF and protection of the GI mucosa in ulcer diseases.
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Affiliation(s)
- Weixi Shan
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Yanxia Hu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jianhong Ding
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Xiaoxu Yang
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jun Lou
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qian Du
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qiushi Liao
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Lihong Luo
- Department of Oncology and Geriatrics, Traditional Chinese Medicine Hospital of Chishui City, Guizhou 564700, P.R. China
| | - Jingyu Xu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Rui Xie
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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21
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Hannigan KI, Bossey AP, Foulkes HJL, Drumm BT, Baker SA, Ward SM, Sanders KM, Keef KD, Cobine CA. A novel intramuscular Interstitial Cell of Cajal is a candidate for generating pacemaker activity in the mouse internal anal sphincter. Sci Rep 2020; 10:10378. [PMID: 32587396 PMCID: PMC7316801 DOI: 10.1038/s41598-020-67142-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 06/03/2020] [Indexed: 12/14/2022] Open
Abstract
The internal anal sphincter (IAS) generates phasic contractions and tone. Slow waves (SWs) produced by interstitial cells of Cajal (ICC) underlie phasic contractions in other gastrointestinal regions. SWs are also present in the IAS where only intramuscular ICC (ICC-IM) are found, however the evidence linking ICC-IM to SWs is limited. This study examined the possible relationship between ICC-IM and SWs by recording Ca2+ transients in mice expressing a genetically-encoded Ca2+-indicator in ICC (Kit-Cre-GCaMP6f). A role for L-type Ca2+ channels (CavL) and anoctamin 1 (ANO1) was tested since each is essential for SW and tone generation. Two distinct ICC-IM populations were identified. Type I cells (36% of total) displayed localised asynchronous Ca2+ transients not dependent on CavL or ANO1; properties typical of ICC-IM mediating neural responses in other gastrointestinal regions. A second novel sub-type, i.e., Type II cells (64% of total) generated rhythmic, global Ca2+ transients at the SW frequency that were synchronised with neighbouring Type II cells and were abolished following blockade of either CavL or ANO1. Thus, the spatiotemporal characteristics of Type II cells and their dependence upon CavL and ANO1 all suggest that these cells are viable candidates for the generation of SWs and tone in the IAS.
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Affiliation(s)
- Karen I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Aaron P Bossey
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Holly J L Foulkes
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Kathleen D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA.
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22
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Grainger N, Freeman RS, Shonnard CC, Drumm BT, Koh SD, Ward SM, Sanders KM. Identification and classification of interstitial cells in the mouse renal pelvis. J Physiol 2020; 598:3283-3307. [PMID: 32415739 DOI: 10.1113/jp278888] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 04/29/2020] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Platelet-derived growth factor receptor-α (PDGFRα) is a novel biomarker along with smooth myosin heavy chain for the pacemaker cells (previously termed 'atypical' smooth muscle cells) in the murine and cynomolgus monkey pelvis-kidney junction. PDGFRα+ cells present in adventitial and urothelial layers of murine renal pelvis do not express smooth muscle myosin heavy chain (smMHC) but are in close apposition to nerve fibres. Most c-Kit+ cells in the renal pelvis are mast cells. Mast cells (CD117+ /CD45+ ) are more abundant in the proximal renal pelvis and pelvis-kidney junction regions whereas c-Kit+ interstitial cells (CD117+ /CD45- ) are found predominantly in the distal renal pelvis and ureteropelvic junction. PDGFRα+ cells are distinct from c-Kit+ interstitial cells. A subset of PDGFRα+ cells express the Ca2+ -activated Cl- channel, anoctamin-1, across the entire renal pelvis. Spontaneous Ca2+ transients were observed in c-Kit+ interstitial cells, smMHC+ PDGFRα cells and smMHC- PDGFRα cells using mice expressing genetically encoded Ca2+ sensors. ABSTRACT Rhythmic contractions of the renal pelvis transport urine from the kidneys into the ureter. Specialized pacemaker cells, termed atypical smooth muscle cells (ASMCs), are thought to drive the peristaltic contractions of typical smooth muscle cells (TSMCs) in the renal pelvis. Interstitial cells (ICs) in close proximity to ASMCs and TSMCs have been described, but the role of these cells is poorly understood. The presence and distributions of platelet-derived growth factor receptor-α+ (PDGFRα+ ) ICs in the pelvis-kidney junction (PKJ) and distal renal pelvis were evaluated. We found PDGFRα+ ICs in the adventitial layers of the pelvis, the muscle layer of the PKJ and the adventitia of the distal pelvis. PDGFRα+ ICs were distinct from c-Kit+ ICs in the renal pelvis. c-Kit+ ICs are a minor population of ICs in murine renal pelvis. The majority of c-Kit+ cells were mast cells. PDGFRα+ cells in the PKJ co-expressed smooth muscle myosin heavy chain (smMHC) and several other smooth muscle gene transcripts, indicating these cells are ASMCs, and PDGFRα is a novel biomarker for ASMCs. PDGFRα+ cells also express Ano1, which encodes a Ca2+ -activated Cl- conductance that serves as a primary pacemaker conductance in ICs of the GI tract. Spontaneous Ca2+ transients were observed in c-Kit+ ICs, smMHC+ PDGFRα cells and smMHC- PDGFRα cells using genetically encoded Ca2+ sensors. A reporter strain of mice with enhanced green fluorescent protein driven by the endogenous promotor for Pdgfra was shown to be a powerful new tool for isolating and characterizing the phenotype and functions of these cells in the renal pelvis.
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Affiliation(s)
- Nathan Grainger
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Ryan S Freeman
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Cameron C Shonnard
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Bernard T Drumm
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Sang Don Koh
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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23
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He Y, Xu P, Wang C, Xia Y, Yu M, Yang Y, Yu K, Cai X, Qu N, Saito K, Wang J, Hyseni I, Robertson M, Piyarathna B, Gao M, Khan SA, Liu F, Chen R, Coarfa C, Zhao Z, Tong Q, Sun Z, Xu Y. Estrogen receptor-α expressing neurons in the ventrolateral VMH regulate glucose balance. Nat Commun 2020; 11:2165. [PMID: 32358493 PMCID: PMC7195451 DOI: 10.1038/s41467-020-15982-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/06/2020] [Indexed: 12/20/2022] Open
Abstract
Brain glucose-sensing neurons detect glucose fluctuations and prevent severe hypoglycemia, but mechanisms mediating functions of these glucose-sensing neurons are unclear. Here we report that estrogen receptor-α (ERα)-expressing neurons in the ventrolateral subdivision of the ventromedial hypothalamic nucleus (vlVMH) can sense glucose fluctuations, being glucose-inhibited neurons (GI-ERαvlVMH) or glucose-excited neurons (GE-ERαvlVMH). Hypoglycemia activates GI-ERαvlVMH neurons via the anoctamin 4 channel, and inhibits GE-ERαvlVMH neurons through opening the ATP-sensitive potassium channel. Further, we show that GI-ERαvlVMH neurons preferentially project to the medioposterior arcuate nucleus of the hypothalamus (mpARH) and GE-ERαvlVMH neurons preferentially project to the dorsal Raphe nuclei (DRN). Activation of ERαvlVMH to mpARH circuit and inhibition of ERαvlVMH to DRN circuit both increase blood glucose. Thus, our results indicate that ERαvlVMH neurons detect glucose fluctuations and prevent severe hypoglycemia in mice.
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Affiliation(s)
- Yanlin He
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Pingwen Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Chunmei Wang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yan Xia
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Meng Yu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yongjie Yang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kaifan Yu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Xing Cai
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Na Qu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kenji Saito
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Julia Wang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Ilirjana Hyseni
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Matthew Robertson
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Badrajee Piyarathna
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Min Gao
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Sohaib A Khan
- Department of Cell and Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati, College of Medicine, Cincinnati, OH, 45267, USA
| | - Feng Liu
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX, 78229, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Cristian Coarfa
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Zhongming Zhao
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Zheng Sun
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
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24
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Parsons SP, Huizinga JD. A myogenic motor pattern in mice lacking myenteric interstitial cells of Cajal explained by a second coupled oscillator network. Am J Physiol Gastrointest Liver Physiol 2020; 318:G225-G243. [PMID: 31813235 PMCID: PMC7052571 DOI: 10.1152/ajpgi.00311.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are a network of coupled oscillators in the small intestine that generate rhythmic electrical phase waves leading to corresponding waves of contraction, yet rhythmic action potentials and intercellular calcium waves have been recorded from c-kit-mutant mice that lack the ICC-MP, suggesting that there may be a second pacemaker network. The gap junction blocker carbenoxolone induced a "pinstripe" motor pattern consisting of rhythmic "stripes" of contraction that appeared simultaneously across the intestine with a period of ~4 s. The infinite velocity of these stripes suggested they were generated by a coupled oscillator network, which we call X. In c-kit mutants rhythmic contraction waves with the period of X traveled the length of the intestine, before the induction of the pinstripe pattern by carbenoxolone. Thus X is not the ICC-MP and appears to operate under physiological conditions, a fact that could explain the viability of these mice. Individual stripes consisted of a complex pattern of bands of contraction and distension, and between stripes there could be slide waves and v waves of contraction. We hypothesized that these phenomena result from an interaction between X and the circular muscle that acts as a damped oscillator. A mathematical model of two chains of coupled Fitzhugh-Nagumo systems, representing X and circular muscle, supported this hypothesis. The presence of a second coupled oscillator network in the small intestine underlines the complexity of motor pattern generation in the gut.NEW & NOTEWORTHY Physiological experiments and a mathematical model indicate a coupled oscillator network in the small intestine in addition to the c-kit-expressing myenteric interstitial cells of Cajal. This network interacts with the circular muscle, which itself acts as a system of damped oscillators, to generate physiological contraction waves in c-kit (W) mutant mice.
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Affiliation(s)
- Sean P. Parsons
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jan D. Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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25
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Hyuga S, Danielsson J, Vink J, Fu XW, Wapner R, Gallos G. Functional comparison of anoctamin 1 antagonists on human uterine smooth muscle contractility and excitability. J Smooth Muscle Res 2019; 54:28-42. [PMID: 29937453 PMCID: PMC6013749 DOI: 10.1540/jsmr.54.28] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background: Pre-term birth is a major health care challenge
throughout the world, and preterm labor represents a potentially reversible
component of this problem. Current tocolytics do not improve preterm labor
beyond 48 h. We have previously shown that anoctamin 1 (ANO1) channel blockade
results in relaxation of pre-contracted human uterine smooth muscle (USM). Three
drug classes with reported medicinal effects in humans also have members with
ANO1 antagonism. In this study, we compared the ability of representatives from
these 3 classes to reduce human USM contractility and excitability.
Objective: This study sought to examine the comparative potency
of 3 ANO1 antagonists on pregnant human USM relaxation, contraction frequency
reduction, inhibition of intracellular calcium release and membrane
hyperpolarization. Methods: Experiments were performed using: 1)
Ex vivo organ bath (human pregnant tissue), 2)
Oxytocin-induced calcium flux (in vitro human USM cells) and 3)
Membrane potential assay (in vitro human USM cells).
Results: Benzbromarone (BB) demonstrated the greatest potency
among the compounds tested with respect to force, frequency inhibition, reducing
calcium elevation and depolarizing membrane potential. Conclusion:
While all 3 ANO1 antagonists attenuate pregnant human uterine tissue
contractility and excitability, BB is the most potent tocolytic drug. Our
findings may serve as a foundation for future structure-function analyses for
novel tocolytic drug development.
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Affiliation(s)
- Shunsuke Hyuga
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, Columbia University Medical Center, New York, NY
| | - Jennifer Danielsson
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, Columbia University Medical Center, New York, NY
| | - Joy Vink
- Department of Obstetrics & Gynecology, Columbia University College of Physicians and Surgeons, Columbia University Medical Center, New York, NY
| | - Xiao Wen Fu
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, Columbia University Medical Center, New York, NY
| | - Ronald Wapner
- Department of Obstetrics & Gynecology, Columbia University College of Physicians and Surgeons, Columbia University Medical Center, New York, NY
| | - George Gallos
- Department of Anesthesiology, Columbia University College of Physicians and Surgeons, Columbia University Medical Center, New York, NY
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26
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Drumm BT, Hwang SJ, Baker SA, Ward SM, Sanders KM. Ca 2+ signalling behaviours of intramuscular interstitial cells of Cajal in the murine colon. J Physiol 2019; 597:3587-3617. [PMID: 31124144 DOI: 10.1113/jp278036] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 05/23/2019] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Colonic intramuscular interstitial cells of Cajal (ICC-IM) exhibit spontaneous Ca2+ transients manifesting as stochastic events from multiple firing sites with propagating Ca2+ waves occasionally observed. Firing of Ca2+ transients in ICC-IM is not coordinated with adjacent ICC-IM in a field of view or even with events from other firing sites within a single cell. Ca2+ transients, through activation of Ano1 channels and generation of inward current, cause net depolarization of colonic muscles. Ca2+ transients in ICC-IM rely on Ca2+ release from the endoplasmic reticulum via IP3 receptors, spatial amplification from RyRs and ongoing refilling of ER via the sarcoplasmic/endoplasmic-reticulum-Ca2+ -ATPase. ICC-IM are sustained by voltage-independent Ca2+ influx via store-operated Ca2+ entry. Some of the properties of Ca2+ in ICC-IM in the colon are similar to the behaviour of ICC located in the deep muscular plexus region of the small intestine, suggesting there are functional similarities between these classes of ICC. ABSTRACT A component of the SIP syncytium that regulates smooth muscle excitability in the colon is the intramuscular class of interstitial cells of Cajal (ICC-IM). All classes of ICC (including ICC-IM) express Ca2+ -activated Cl- channels, encoded by Ano1, and rely upon this conductance for physiological functions. Thus, Ca2+ handling in ICC is fundamental to colonic motility. We examined Ca2+ handling mechanisms in ICC-IM of murine proximal colon expressing GCaMP6f in ICC. Several Ca2+ firing sites were detected in each cell. While individual sites displayed rhythmic Ca2+ events, the overall pattern of Ca2+ transients was stochastic. No correlation was found between discrete Ca2+ firing sites in the same cell or in adjacent cells. Ca2+ transients in some cells initiated Ca2+ waves that spread along the cell at ∼100 µm s-1 . Ca2+ transients were caused by release from intracellular stores, but depended strongly on store-operated Ca2+ entry mechanisms. ICC Ca2+ transient firing regulated the resting membrane potential of colonic tissues as a specific Ano1 antagonist hyperpolarized colonic muscles by ∼10 mV. Ca2+ transient firing was independent of membrane potential and not affected by blockade of L- or T-type Ca2+ channels. Mechanisms regulating Ca2+ transients in the proximal colon displayed both similarities to and differences from the intramuscular type of ICC in the small intestine. Similarities and differences in Ca2+ release patterns might determine how ICC respond to neurotransmission in these two regions of the gastrointestinal tract.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
| | - Sung J Hwang
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
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27
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Myosalpinx Contractions Are Essential for Egg Transport Along the Oviduct and Are Disrupted in Reproductive Tract Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:265-294. [DOI: 10.1007/978-981-13-5895-1_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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28
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Hwang SJ, Pardo DM, Zheng H, Bayguinov Y, Blair PJ, Fortune‐Grant R, Cook RS, Hennig GW, Shonnard MC, Grainger N, Peri LE, Verma SD, Rock J, Sanders KM, Ward SM. Differential sensitivity of gastric and small intestinal muscles to inducible knockdown of anoctamin 1 and the effects on gastrointestinal motility. J Physiol 2019; 597:2337-2360. [PMID: 30843201 PMCID: PMC6487927 DOI: 10.1113/jp277335] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 02/22/2019] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Electrical pacemaking in gastrointestinal muscles is generated by specialized interstitial cells of Cajal that produce the patterns of contractions required for peristalsis and segmentation in the gut. The calcium-activated chloride conductance anoctamin-1 (Ano1) has been shown to be responsible for the generation of pacemaker activity in GI muscles, but this conclusion is established from studies of juvenile animals in which effects of reduced Ano1 on gastric emptying and motor patterns could not be evaluated. Knocking down Ano1 expression using Cre/LoxP technology caused dramatic changes in in gastric motor activity, with disrupted slow waves, abnormal phasic contractions and delayed gastric emptying; modest changes were noted in the small intestine. Comparison of the effects of Ano1 antagonists on muscles from juvenile and adult small intestinal muscles suggests that conductances in addition to Ano1 may develop with age and contribute to pacemaker activity. ABSTRACT Interstitial cells of Cajal (ICC) generate slow waves and transduce neurotransmitter signals in the gastrointestinal (GI) tract, facilitating normal motility patterns. ICC express a Ca2+ -activated Cl- conductance (CaCC), and constitutive knockout of the channel protein anoctamin-1 leads to loss of slow waves in gastric and intestinal muscles. These knockout experiments were performed on juvenile mice. However, additional experiments demonstrated significant differences in the sensitivity of gastric and intestinal muscles to antagonists of anoctamin-1 channels. Furthermore, the significance of anoctamin-1 and the electrical and mechanical behaviours facilitated by this conductance have not been evaluated on the motor behaviours of adult animals. Cre/loxP technology was used to generate cell-specific knockdowns of anoctamin-1 in ICC (KitCreERT2/+ ;Ano1tm2jrr/+ ) in GI muscles. The recombination efficiency of KitCreERT was evaluated with an eGFP reporter, molecular techniques and immunohistochemistry. Electrical and contractile experiments were used to examine the consequences of anoctamin-1 knockdown on pacemaker activity, mechanical responses, gastric motility patterns, gastric emptying and GI transit. Reduced anoctamin-1 caused loss of gastric, but not intestinal slow waves. Irregular spike complexes developed in gastric muscles, leading to uncoordinated antral contractions, delayed gastric emptying and increased total GI transit time. Slow waves in intestinal muscles of juvenile mice were more sensitive to anoctamin-1 antagonists than slow waves in adult muscles. The low susceptibility to anoctamin-1 knockdown and weak efficacy of anoctamin-1 antagonists in inhibiting slow waves in adult small intestinal muscles suggest that a conductance in addition to anoctamin-1 may develop in small intestinal ICC with ageing and contribute to pacemaker activity.
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Affiliation(s)
- Sung Jin Hwang
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - David M. Pardo
- Department of AnatomyUniversity of CaliforniaSan FranciscoSan FranciscoCA94143USA
| | - Haifeng Zheng
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Yulia Bayguinov
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Peter J. Blair
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Rachael Fortune‐Grant
- Faculty of BiologyMedicine and HealthSchool of Biological SciencesUniversity of ManchesterUK
| | - Robert S. Cook
- School of Molecular and Cellular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Grant W. Hennig
- Department of PharmacologyThe University of VermontUVM College of MedicineBurlingtonVT05405USA
| | - Matthew C. Shonnard
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Nathan Grainger
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Lauren E. Peri
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Sonali Deep Verma
- Department of AnatomyUniversity of CaliforniaSan FranciscoSan FranciscoCA94143USA
| | - Jason Rock
- Centre for Regenerative MedicineBoston University School of MedicineBostonMA02118USA
| | - Kenton M. Sanders
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
| | - Sean M. Ward
- Department of Physiology & Cell BiologyUniversity of NevadaReno School of MedicineRenoNV89557USA
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29
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Zawieja SD, Castorena JA, Gui P, Li M, Bulley SA, Jaggar JH, Rock JR, Davis MJ. Ano1 mediates pressure-sensitive contraction frequency changes in mouse lymphatic collecting vessels. J Gen Physiol 2019; 151:532-554. [PMID: 30862712 PMCID: PMC6445586 DOI: 10.1085/jgp.201812294] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/06/2019] [Indexed: 12/16/2022] Open
Abstract
Lymphatic collecting vessels exhibit spontaneous contractions with a pressure-dependent contraction frequency. The initiation of contraction has been proposed to be mediated by the activity of a Ca2+-activated Cl- channel (CaCC). Here, we show that the canonical CaCC Anoctamin 1 (Ano1, TMEM16a) plays an important role in lymphatic smooth muscle pacemaking. We find that isolated murine lymphatic muscle cells express Ano1, and demonstrate functional CaCC currents that can be inhibited by the Ano1 inhibitor benzbromarone. These currents are absent in lymphatic muscle cells from Cre transgenic mouse lines targeted for Ano1 genetic deletion in smooth muscle. We additionally show that loss of functional Ano1 in murine inguinal-axillary lymphatic vessels, whether through genetic manipulation or pharmacological inhibition, results in an impairment of the pressure-frequency relationship that is attributable to a hyperpolarized resting membrane potential and a significantly depressed diastolic depolarization rate preceding each action potential. These changes are accompanied by alterations in action potential shape and duration, and a reduced duration but increased amplitude of the action potential-induced global "Ca2+ flashes" that precede lymphatic contractions. These findings suggest that an excitatory Cl- current provided by Ano1 is critical for mediating the pressure-sensitive contractile response and is a major component of the murine lymphatic action potential.
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Affiliation(s)
- Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Jorge A Castorena
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Simon A Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN
| | - Jason R Rock
- Department of Medicine, Boston University School of Medicine, Boston, MA
| | - Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
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Tonic inhibition of murine proximal colon is due to nitrergic suppression of Ca 2+ signaling in interstitial cells of Cajal. Sci Rep 2019; 9:4402. [PMID: 30867452 PMCID: PMC6416298 DOI: 10.1038/s41598-019-39729-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 01/30/2019] [Indexed: 12/18/2022] Open
Abstract
Spontaneous excitability and contractions of colonic smooth muscle cells (SMCs) are normally suppressed by inputs from inhibitory motor neurons, a behavior known as tonic inhibition. The post-junctional cell(s) mediating tonic inhibition have not been elucidated. We investigated the post-junctional cells mediating tonic inhibition in the proximal colon and whether tonic inhibition results from suppression of the activity of Ano1 channels, which are expressed exclusively in interstitial cells of Cajal (ICC). We found that tetrodotoxin (TTX), an inhibitor of nitric oxide (NO) synthesis, L-NNA, and an inhibitor of soluble guanylyl cyclase, ODQ, greatly enhanced colonic contractions. Ano1 antagonists, benzbromarone and Ani9 inhibited the effects of TTX, L-NNA and ODQ. Ano1 channels are activated by Ca2+ release from the endoplasmic reticulum (ER) in ICC, and blocking Ca2+ release with a SERCA inhibitor (thapsigargin) or a store-operated Ca2+ entry blocker (GSK 7975 A) reversed the effects of TTX, L-NNA and ODQ. Ca2+ imaging revealed that TTX, L-NNA and ODQ increased Ca2+ transient firing in colonic ICC. Our results suggest that tonic inhibition in the proximal colon occurs through suppression of Ca2+ release events in ICC. Suppression of Ca2+ release in ICC limits the open probability of Ano1 channels, reducing the excitability of electrically-coupled SMCs.
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Sanders KM. Spontaneous Electrical Activity and Rhythmicity in Gastrointestinal Smooth Muscles. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:3-46. [PMID: 31183821 PMCID: PMC7035145 DOI: 10.1007/978-981-13-5895-1_1] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The gastrointestinal (GI) tract has multifold tasks of ingesting, processing, and assimilating nutrients and disposing of wastes at appropriate times. These tasks are facilitated by several stereotypical motor patterns that build upon the intrinsic rhythmicity of the smooth muscles that generate phasic contractions in many regions of the gut. Phasic contractions result from a cyclical depolarization/repolarization cycle, known as electrical slow waves, which result from intrinsic pacemaker activity. Interstitial cells of Cajal (ICC) are electrically coupled to smooth muscle cells (SMCs) and generate and propagate pacemaker activity and slow waves. The mechanism of slow waves is dependent upon specialized conductances expressed by pacemaker ICC. The primary conductances responsible for slow waves in mice are Ano1, Ca2+-activated Cl- channels (CaCCs), and CaV3.2, T-type, voltage-dependent Ca2+ channels. Release of Ca2+ from intracellular stores in ICC appears to be the initiator of pacemaker depolarizations, activation of T-type current provides voltage-dependent Ca2+ entry into ICC, as slow waves propagate through ICC networks, and Ca2+-induced Ca2+ release and activation of Ano1 in ICC amplifies slow wave depolarizations. Slow waves conduct to coupled SMCs, and depolarization elicited by these events enhances the open-probability of L-type voltage-dependent Ca2+ channels, promotes Ca2+ entry, and initiates contraction. Phasic contractions timed by the occurrence of slow waves provide the basis for motility patterns such as gastric peristalsis and segmentation. This chapter discusses the properties of ICC and proposed mechanism of electrical rhythmicity in GI muscles.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA.
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Ji Q, Guo S, Wang X, Pang C, Zhan Y, Chen Y, An H. Recent advances in TMEM16A: Structure, function, and disease. J Cell Physiol 2018; 234:7856-7873. [PMID: 30515811 DOI: 10.1002/jcp.27865] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022]
Abstract
TMEM16A (also known as anoctamin 1, ANO1) is the molecular basis of the calcium-activated chloride channels, with ten transmembrane segments. Recently, atomic structures of the transmembrane domains of mouse TMEM16A (mTMEM16A) were determined by single-particle electron cryomicroscopy. This gives us a solid ground to discuss the electrophysiological properties and functions of TMEM16A. TMEM16A is reported to be dually regulated by Ca2+ and voltage. In addition, the dysfunction of TMEM16A has been found to be involved in many diseases including cystic fibrosis, various cancers, hypertension, and gastrointestinal motility disorders. TMEM16A is overexpressed in many cancers, including gastrointestinal stromal tumors, gastric cancer, head and neck squamous cell carcinoma (HNSCC), colon cancer, pancreatic ductal adenocarcinoma, and esophageal cancer. Furthermore, overexpression of TMEM16A is related to the occurrence, proliferation, and migration of tumor cells. To date, several studies have shown that many natural compounds and synthetic compounds have regulatory effects on TMEM16A. These small molecule compounds might be novel drugs for the treatment of diseases caused by TMEM16A dysfunction in the future. In addition, recent studies have shown that TMEM16A plays different roles in different diseases through different signal transduction pathways. This review discusses the topology, electrophysiological properties, modulators and functions of TMEM16A in mediates nociception, gastrointestinal dysfunction, hypertension, and cancer and focuses on multiple regulatory mechanisms regarding TMEM16A.
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Affiliation(s)
- Qiushuang Ji
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Shuai Guo
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Xuzhao Wang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yong Zhan
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yafei Chen
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hailong An
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
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Sung TS, Hwang SJ, Koh SD, Bayguinov Y, Peri LE, Blair PJ, Webb TI, Pardo DM, Rock JR, Sanders KM, Ward SM. The cells and conductance mediating cholinergic neurotransmission in the murine proximal stomach. J Physiol 2018; 596:1549-1574. [PMID: 29430647 PMCID: PMC5924836 DOI: 10.1113/jp275478] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/26/2018] [Indexed: 12/23/2022] Open
Abstract
KEY POINTS Enteric neurotransmission is essential for gastrointestinal (GI) motility, although the cells and conductances responsible for post-junctional responses are controversial. The calcium-activated chloride conductance (CaCC), anoctamin-1 (Ano1), was expressed by intramuscular interstitial cells of Cajal (ICC-IM) in proximal stomach and not resolved in smooth muscle cells (SMCs). Cholinergic nerve fibres were closely apposed to ICC-IM. Conductances activated by cholinergic stimulation in isolated ICC-IM and SMCs were determined. A CaCC was activated by carbachol in ICC-IM and a non-selective cation conductance in SMCs. Responses to cholinergic nerve stimulation were studied. Excitatory junction potentials (EJPs) and mechanical responses were evoked in wild-type mice but absent or greatly reduced with knockout/down of Ano1. Drugs that block Ano1 inhibited the conductance activated by carbachol in ICC-IM and EJPs and mechanical responses in tissues. The data of the present study suggest that electrical and mechanical responses to cholinergic nerve stimulation are mediated by Ano1 expressed in ICC-IM and not SMCs. ABSTRACT Enteric motor neurotransmission is essential for normal gastrointestinal (GI) motility. Controversy exists regarding the cells and ionic conductance(s) that mediate post-junctional neuroeffector responses to motor neurotransmitters. Isolated intramuscular ICC (ICC-IM) and smooth muscle cells (SMCs) from murine fundus muscles were used to determine the conductances activated by carbachol (CCh) in each cell type. The calcium-activated chloride conductance (CaCC), anoctamin-1 (Ano1) is expressed by ICC-IM but not resolved in SMCs, and CCh activated a Cl- conductance in ICC-IM and a non-selective cation conductance in SMCs. We also studied responses to nerve stimulation using electrical-field stimulation (EFS) of intact fundus muscles from wild-type and Ano1 knockout mice. EFS activated excitatory junction potentials (EJPs) in wild-type mice, although EJPs were absent in mice with congenital deactivation of Ano1 and greatly reduced in animals in which the CaCC-Ano1 was knocked down using Cre/loxP technology. Contractions to cholinergic nerve stimulation were also greatly reduced in Ano1 knockouts. SMCs cells also have receptors and ion channels activated by muscarinic agonists. Blocking acetylcholine esterase with neostigmine revealed a slow depolarization that developed after EJPs in wild-type mice. This depolarization was still apparent in mice with genetic deactivation of Ano1. Pharmacological blockers of Ano1 also inhibited EJPs and contractile responses to muscarinic stimulation in fundus muscles. The data of the present study are consistent with the hypothesis that ACh released from motor nerves binds muscarinic receptors on ICC-IM with preference and activates Ano1. If metabolism of acetylcholine is inhibited, ACh overflows and binds to extrajunctional receptors on SMCs, eliciting a slower depolarization response.
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Affiliation(s)
- Tae Sik Sung
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sung Jin Hwang
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Yulia Bayguinov
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Lauen E. Peri
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Peter J. Blair
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Timothy I. Webb
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - David M. Pardo
- Department of AnatomyUniversity of CaliforniaSan FranciscoCAUSA
| | - Jason R. Rock
- Center for Regenerative MedicineBoston University School of MedicineBostonMAUSA
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sean M. Ward
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
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Fedigan S, Bradley E, Webb T, Large RJ, Hollywood MA, Thornbury KD, McHale NG, Sergeant GP. Effects of new-generation TMEM16A inhibitors on calcium-activated chloride currents in rabbit urethral interstitial cells of Cajal. Pflugers Arch 2017; 469:1443-1455. [PMID: 28733893 DOI: 10.1007/s00424-017-2028-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 06/21/2017] [Accepted: 07/03/2017] [Indexed: 12/18/2022]
Abstract
Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit Ca2+-activated Cl- currents (I ClCa) that are important for the development of urethral tone. Here, we examined if TMEM16A (ANO1) contributed to this activity by examining the effect of "new-generation" TMEM16A inhibitors, CACCinh-A01 and T16Ainh-A01, on I ClCa recorded from freshly isolated rabbit urethral ICC (RUICC) and on contractions of intact strips of rabbit urethra smooth muscle. Real-time quantitative PCR experiments demonstrated that TMEM16A was highly expressed in rabbit urethra smooth muscle, in comparison to TMEM16B and TMEM16F. Single-cell RT-PCR experiments revealed that only TMEM16A was expressed in freshly isolated RUICC. Depolarization-evoked I ClCa in isolated RUICC, recorded using voltage clamp, were inhibited by CACCinh-A01 and T16Ainh-A01 with IC50 values of 1.2 and 3.4 μM, respectively. Similarly, spontaneous transient inward currents (STICs) recorded from RUICC voltage clamped at -60 mV and spontaneous transient depolarizations (STDs), recorded in current clamp, were also inhibited by CACCinh-A01 and T16Ainh-A01. In contrast, spontaneous Ca2+ waves in isolated RUICC were only partially reduced by CACCinh-A01 and T16Ainh-A01. Finally, neurogenic contractions of strips of rabbit urethra smooth muscle (RUSM), evoked by electric field stimulation (EFS), were also significantly reduced by CACCinh-A01 and T16Ainh-A01. These data are consistent with the idea that TMEM16A is involved with CACCs in RUICC and in contraction of rabbit urethral smooth muscle.
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Affiliation(s)
- Stephen Fedigan
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Eamonn Bradley
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Timothy Webb
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Roddy J Large
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Mark A Hollywood
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Keith D Thornbury
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Noel G McHale
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Gerard P Sergeant
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.
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Malysz J, Gibbons SJ, Saravanaperumal SA, Du P, Eisenman ST, Cao C, Oh U, Saur D, Klein S, Ordog T, Farrugia G. Conditional genetic deletion of Ano1 in interstitial cells of Cajal impairs Ca 2+ transients and slow waves in adult mouse small intestine. Am J Physiol Gastrointest Liver Physiol 2017; 312:G228-G245. [PMID: 27979828 PMCID: PMC5401988 DOI: 10.1152/ajpgi.00363.2016] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/05/2016] [Accepted: 12/12/2016] [Indexed: 01/31/2023]
Abstract
Myenteric plexus interstitial cells of Cajal (ICC-MY) in the small intestine are Kit+ electrical pacemakers that express the Ano1/TMEM16A Ca2+-activated Cl- channel, whose functions in the gastrointestinal tract remain incompletely understood. In this study, an inducible Cre-LoxP-based approach was used to advance the understanding of Ano1 in ICC-MY of adult mouse small intestine. KitCreERT2/+;Ano1Fl/Fl mice were treated with tamoxifen or vehicle, and small intestines (mucosa free) were examined. Quantitative RT-PCR demonstrated ~50% reduction in Ano1 mRNA in intestines of conditional knockouts (cKOs) compared with vehicle-treated controls. Whole mount immunohistochemistry showed a mosaic/patchy pattern loss of Ano1 protein in ICC networks. Ca2+ transients in ICC-MY network of cKOs displayed reduced duration compared with highly synchronized controls and showed synchronized and desynchronized profiles. When matched, the rank order for Ano1 expression in Ca2+ signal imaged fields of view was as follows: vehicle controls>>>cKO(synchronized)>cKO(desynchronized). Maintenance of Ca2+ transients' synchronicity despite high loss of Ano1 indicates a large functional reserve of Ano1 in the ICC-MY network. Slow waves in cKOs displayed reduced duration and increased inter-slow-wave interval and occurred in regular- and irregular-amplitude oscillating patterns. The latter activity suggested ongoing interaction by independent interacting oscillators. Lack of slow waves and depolarization, previously reported for neonatal constitutive knockouts, were also seen. In summary, Ano1 in adults regulates gastrointestinal function by determining Ca2+ transients and electrical activity depending on the level of Ano1 expression. Partial Ano1 loss results in Ca2+ transients and slow waves displaying reduced duration, while complete and widespread absence of Ano1 in ICC-MY causes lack of slow wave and desynchronized Ca2+ transients.NEW & NOTEWORTHY The Ca2+-activated Cl- channel, Ano1, in interstitial cells of Cajal (ICC) is necessary for normal gastrointestinal motility. We knocked out Ano1 to varying degrees in ICC of adult mice. Partial knockout of Ano1 shortened the widths of electrical slow waves and Ca2+ transients in myenteric ICC but Ca2+ transient synchronicity was preserved. Near-complete knockout was necessary for transient desynchronization and loss of slow waves, indicating a large functional reserve of Ano1 in ICC.
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Affiliation(s)
- John Malysz
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | - Simon J Gibbons
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | | | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Seth T Eisenman
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | - Chike Cao
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | - Uhtaek Oh
- Sensory Research Center, CRI, College of Pharmacy, Seoul National University, Seoul, Republic of Korea; and
| | - Dieter Saur
- Department of Internal Medicine II, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Sabine Klein
- Department of Internal Medicine II, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Tamas Ordog
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
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Cobine CA, Hannah EE, Zhu MH, Lyle HE, Rock JR, Sanders KM, Ward SM, Keef KD. ANO1 in intramuscular interstitial cells of Cajal plays a key role in the generation of slow waves and tone in the internal anal sphincter. J Physiol 2017; 595:2021-2041. [PMID: 28054347 DOI: 10.1113/jp273618] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/16/2016] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The internal anal sphincter develops tone important for maintaining high anal pressure and continence. Controversy exists regarding the mechanisms underlying tone development. We examined the hypothesis that tone depends upon electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca2+ -activated Cl- channels (ANO1, encoded by Ano1) and voltage-dependent L-type Ca2+ channels (CavL , encoded by Cacna1c). Measurement of membrane potential and contraction indicated that ANO1 and CavL have a central role in SW generation, phasic contractions and tone, independent of stretch. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Ano1 and Cacna1c expression levels were examined by quantitative PCR in fluorescence-activated cell sorting. ICC-IM were the predominant cell type expressing ANO1 and the most likely candidate for SW generation. SWs in ICC-IM are proposed to conduct to smooth muscle where Ca2+ entry via CavL results in phasic activity that sums to produce tone. ABSTRACT The mechanism underlying tone generation in the internal anal sphincter (IAS) is controversial. We examined the hypothesis that tone depends upon generation of electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca2+ -activated Cl- channels (encoded by Ano1) and voltage-dependent L-type Ca2+ channels (encoded by Cacna1c). Phasic contractions and tone in the IAS were nearly abolished by ANO1 and CavL antagonists. ANO1 antagonists also abolished SWs as well as transient depolarizations that persisted after addition of CavL antagonists. Tone development in the IAS did not require stretch of muscles, and the sensitivity of contraction to ANO1 antagonists was the same in stretched versus un-stretched muscles. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Dual labelling revealed that ANO1 expression could be resolved in ICC but not smooth muscle cells (SMCs) in the IAS and rectum. Ano1, Cacna1c and Kit gene expression were the same in extracts of IAS and rectum muscles. In IAS cells isolated with fluorescence-activated cell sorting, Ano1 expression was 26.5-fold greater in ICC than in SMCs while Cacna1c expression was only 2-fold greater in SMCs than in ICC. These data support a central role for ANO1 and CavL in the generation of SWs and tone in the IAS. ICC-IM are the probable cellular candidate for ANO1 currents and SW generation. We propose that ANO1 and CavL collaborate to generate SWs in ICC-IM followed by conduction to adjacent SMCs where phasic calcium entry through CavL sums to produce tone.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - E E Hannah
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - M H Zhu
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - H E Lyle
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - J R Rock
- Department of Anatomy, UCSF School of Medicine, San Francisco, CA, 94143, USA
| | - K M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - S M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
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Brijs J, Hennig GW, Kellermann AM, Axelsson M, Olsson C. The presence and role of interstitial cells of Cajal in the proximal intestine of shorthorn sculpin (Myoxocephalus scorpius). ACTA ACUST UNITED AC 2016; 220:347-357. [PMID: 27875260 DOI: 10.1242/jeb.141523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 11/03/2016] [Indexed: 12/27/2022]
Abstract
Rhythmic contractions of the mammalian gastrointestinal tract can occur in the absence of neuronal or hormonal stimulation owing to the generation of spontaneous electrical activity by interstitial cells of Cajal (ICC) that are electrically coupled to smooth muscle cells. The myogenically driven component of gastrointestinal motility patterns in fish probably also involves ICC; however, little is known of their presence, distribution and function in any fish species. In the present study, we combined immunohistochemistry and in vivo recordings of intestinal motility to investigate the involvement of ICC in the motility of the proximal intestine in adult shorthorn sculpin (Myoxocephalus scorpius). Antibodies against anoctamin 1 (Ano1, a Ca2+-activated Cl- channel), revealed a dense network of multipolar, repeatedly branching cells in the myenteric region of the proximal intestine, similar in many regards to the mammalian ICC-MY network. The addition of benzbromarone, a potent blocker of Ano1, altered the motility patterns seen in vivo after neural blockade with TTX. The results indicate that ICC are integral for the generation and propagation of the majority of rhythmic contractile patterns in fish, although their frequency and amplitude can be modulated via neural activity.
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Affiliation(s)
- Jeroen Brijs
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Göteborg, Sweden
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Reno, Nevada, NV 89557, USA
| | - Anna-Maria Kellermann
- Department of Nature and Engineering, Bremen University of Applied Sciences, Bremen 28199, Germany
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Göteborg, Sweden
| | - Catharina Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Göteborg, Sweden
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Hwang SJ, Basma N, Sanders KM, Ward SM. Effects of new-generation inhibitors of the calcium-activated chloride channel anoctamin 1 on slow waves in the gastrointestinal tract. Br J Pharmacol 2016; 173:1339-49. [PMID: 26774021 DOI: 10.1111/bph.13431] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 01/06/2016] [Accepted: 01/08/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE High-throughput screening of compound libraries using genetically encoded fluorescent biosensors has identified several second-generation. low MW inhibitors of the calcium-activated chloride channel anoctamin 1 (CaCC/Ano1). Here we have (i) examined the effects of these Ano1 inhibitors on gastric and intestinal pacemaker activity; (ii) compared the effects of these inhibitors with those of the more classical CaCC inhibitor, 5-nitro-2-(3-phenylpropylalanine) benzoate (NPPB); (ii) examined the mode of action of these compounds on the waveform of pacemaker activity; and (iii) compared differences in the sensitivity between gastric and intestinal pacemaker activity to the Ano1 inhibitors. EXPERIMENTAL APPROACH Using intracellular microelectrode recordings of gastric and intestinal muscle preparations from C57BL/6 mice, the dose-dependent effects of Ano1 inhibitors were examined on spontaneous electrical slow waves. KEY RESULTS The efficacy of second-generation Ano1 inhibitors on gastric and intestinal pacemaker activity differed significantly. Antral slow waves were more sensitive to these inhibitors than intestinal slow waves. CaCCinh -A01 and benzbromarone were the most potent at inhibiting slow waves in both muscle preparations and more potent than NPPB. Dichlorophene and hexachlorophene were equally potent at inhibiting slow waves. Surprisingly, slow waves were relatively insensitive to T16Ainh -A01 in both preparations. CONCLUSIONS AND IMPLICATIONS We have identified several second-generation Ano1 inhibitors, blocking gastric and intestinal pacemaker activity. Different sensitivities to Ano1 inhibitors between stomach and intestine suggest the possibility of different splice variants in these two organs or the involvement of other conductances in the generation and propagation of pacemaker activity in these tissues.
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Affiliation(s)
- Sung Jin Hwang
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Naseer Basma
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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