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Ochoa SV, Otero L, Aristizabal-Pachon AF, Hinostroza F, Carvacho I, Torres YP. Hypoxic Regulation of the Large-Conductance, Calcium and Voltage-Activated Potassium Channel, BK. Front Physiol 2022; 12:780206. [PMID: 35002762 PMCID: PMC8727448 DOI: 10.3389/fphys.2021.780206] [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: 09/20/2021] [Accepted: 11/15/2021] [Indexed: 11/15/2022] Open
Abstract
Hypoxia is a condition characterized by a reduction of cellular oxygen levels derived from alterations in oxygen balance. Hypoxic events trigger changes in cell-signaling cascades, oxidative stress, activation of pro-inflammatory molecules, and growth factors, influencing the activity of various ion channel families and leading to diverse cardiovascular diseases such as myocardial infarction, ischemic stroke, and hypertension. The large-conductance, calcium and voltage-activated potassium channel (BK) has a central role in the mechanism of oxygen (O2) sensing and its activity has been related to the hypoxic response. BK channels are ubiquitously expressed, and they are composed by the pore-forming α subunit and the regulatory subunits β (β1–β4), γ (γ1–γ4), and LINGO1. The modification of biophysical properties of BK channels by β subunits underly a myriad of physiological function of these proteins. Hypoxia induces tissue-specific modifications of BK channel α and β subunits expression. Moreover, hypoxia modifies channel activation kinetics and voltage and/or calcium dependence. The reported effects on the BK channel properties are associated with events such as the increase of reactive oxygen species (ROS) production, increases of intracellular Calcium ([Ca2+]i), the regulation by Hypoxia-inducible factor 1α (HIF-1α), and the interaction with hemeproteins. Bronchial asthma, chronic obstructive pulmonary diseases (COPD), and obstructive sleep apnea (OSA), among others, can provoke hypoxia. Untreated OSA patients showed a decrease in BK-β1 subunit mRNA levels and high arterial tension. Treatment with continuous positive airway pressure (CPAP) upregulated β1 subunit mRNA level, decreased arterial pressures, and improved endothelial function coupled with a reduction in morbidity and mortality associated with OSA. These reports suggest that the BK channel has a role in the response involved in hypoxia-associated hypertension derived from OSA. Thus, this review aims to describe the mechanisms involved in the BK channel activation after a hypoxic stimulus and their relationship with disorders like OSA. A deep understanding of the molecular mechanism involved in hypoxic response may help in the therapeutic approaches to treat the pathological processes associated with diseases involving cellular hypoxia.
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Affiliation(s)
- Sara V Ochoa
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia.,Semillero de Investigación, Biofísica y Fisiología de Canales Iónicos, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Liliana Otero
- Center of Dental Research Dentistry Faculty, Pontificia Universidad Javeriana, Bogotá, Colombia
| | | | - Fernando Hinostroza
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del Maule, Talca, Chile.,Centro de Investigación de Estudios Avanzados del Maule, CIEAM, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile.,Facultad de Ciencias de la Salud, Centro de Investigación en Neuropsicología y Neurociencias Cognitivas, Universidad Católica del Maule, Talca, Chile
| | - Ingrid Carvacho
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del Maule, Talca, Chile
| | - Yolima P Torres
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia.,Semillero de Investigación, Biofísica y Fisiología de Canales Iónicos, Pontificia Universidad Javeriana, Bogotá, Colombia
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2
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Yoo HY, Kim SJ. Oxygen-dependent regulation of ion channels: acute responses, post-translational modification, and response to chronic hypoxia. Pflugers Arch 2021; 473:1589-1602. [PMID: 34142209 DOI: 10.1007/s00424-021-02590-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/15/2021] [Accepted: 05/30/2021] [Indexed: 12/19/2022]
Abstract
Oxygen is a vital element for the survival of cells in multicellular aerobic organisms such as mammals. Lack of O2 availability caused by environmental or pathological conditions leads to hypoxia. Active oxygen distribution systems (pulmonary and circulatory) and their neural control mechanisms ensure that cells and tissues remain oxygenated. However, O2-carrying blood cells as well as immune and various parenchymal cells experience wide variations in partial pressure of oxygen (PO2) in vivo. Hence, the reactive modulation of the functions of the oxygen distribution systems and their ability to sense PO2 are critical. Elucidating the physiological responses of cells to variations in PO2 and determining the PO2-sensing mechanisms at the biomolecular level have attracted considerable research interest in the field of physiology. Herein, we review the current knowledge regarding ion channel-dependent oxygen sensing and associated signalling pathways in mammals. First, we present the recent findings on O2-sensing ion channels in representative chemoreceptor cells as well as in other types of cells such as immune cells. Furthermore, we highlight the transcriptional regulation of ion channels under chronic hypoxia and its physiological implications and summarize the findings of studies on the post-translational modification of ion channels under hypoxic or ischemic conditions.
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Affiliation(s)
- Hae Young Yoo
- Department of Nursing, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea. .,Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
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3
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Zhu JJ, Wu SH, Chen X, Jiang TT, Li XQ, Li JM, Yan Y, Wu XJ, Liu YY, Dong P. Tanshinone IIA Suppresses Hypoxia-induced Apoptosis in Medial Vestibular Nucleus Cells Via a Skp2/BKCa Axis. Curr Pharm Des 2020; 26:4185-4194. [PMID: 32484767 DOI: 10.2174/1381612826666200602144405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/13/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND The aim of the present study was to investigate the protective effects of Tanshinone IIA (Tan IIA) on hypoxia-induced injury in the medial vestibular nucleus (MVN) cells. METHODS An in vitro hypoxia model was established using MVN cells exposed to hypoxia. The hypoxia-induced cell damage was confirmed by assessing cell viability, apoptosis and expression of apoptosis-associated proteins. Oxidative stress and related indicators were also measured following hypoxia modeling and Tan IIA treatment, and the genes potentially involved in the response were predicted using multiple GEO datasets. RESULTS The results of the present study showed that Tan IIA significantly increased cell viability, decreased cell apoptosis and decreased the ratio of Bax/Bcl-2 in hypoxia treated cells. In addition, hypoxia treatment increased oxidative stress in MVN cells, and treatment with Tan IIA reduced the oxidative stress. The expression of SPhase Kinase Associated Protein 2 (SKP2) was upregulated in hypoxia treated cells, and Tan IIA treatment reduced the expression of SKP2. Mechanistically, SKP2 interacted with large-conductance Ca2+-activated K+ channels (BKCa), regulating its expression, and BKCa knockdown alleviated the protective effects of Tan IIA on hypoxia induced cell apoptosis. CONCLUSION The results of the present study suggested that Tan IIA had a protective effect on hypoxia-induced cell damage through its anti-apoptotic and anti-oxidative activity via an SKP2/BKCa axis. These findings suggest that Tan IIA may be a potential therapeutic for the treatment of hypoxia-induced vertigo.
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Affiliation(s)
- Jing-Jing Zhu
- Department of Otolaryngology, Head and Neck Surgery, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China
| | - Shu-Hui Wu
- Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Xiang Chen
- Department of General Surgery, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Ting-Ting Jiang
- Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Xin-Qian Li
- Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Jing-Min Li
- Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Yong Yan
- Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Xue-Jun Wu
- Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China
| | - Yu-Ying Liu
- Department of Otolaryngology, Head and Neck Surgery, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China
| | - Pin Dong
- Department of Otolaryngology, Head and Neck Surgery, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China
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4
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Yin H, Zhang X, Li K, Li Z, Yang Z. Effects of miR-200b-3p inhibition on the TRPC6 and BK Ca channels of podocytes. Arch Biochem Biophys 2018; 653:80-89. [PMID: 29958896 DOI: 10.1016/j.abb.2018.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/22/2018] [Accepted: 06/25/2018] [Indexed: 12/17/2022]
Abstract
Transient receptor potential canonical 6 (TRPC6) and large-conductance Ca2+-activated K+ channels (BKCa), two of the key ion channels for blood filtration function of podocytes, have been implicated in the pathogenesis of kidney diseases. Moreover, it has been reported that miR-200 b plays an important role in regulating the biological processes of podocytes. In this study, we aimed to examine whether there was a relationship between miR-200 b-3p and the two ion channels. It was suggested that miR-200 b-3p down-regulation inhibited the currents of TRPC6 and BKCa channels. It also showed that miR-200 b-3p inhibition reduced the levels of protein expression and mRNA transcription of TRPC6 and BKCa channels. Moreover, the down-regulation of miR-200 b-3p resulted in the decrease of the intracellular Ca2+ concentration. It was also suggested that the decrease of BKCa currents resulting from miR-200 b-3p inhibition could be regulated by TRPC6 channels. TRPC6 blockage also inhibited BKCa currents and reduced the level of BKCa expression. These results together suggested that miR-200 b-3p inhibition reduced the currents of TRPC6, which led to the decrease of intracellular Ca2+ concentration. The decrease of Ca2+ source required for BKCa activation may result in the inhibition of BKCa currents.
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Affiliation(s)
- Hongqiang Yin
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, 300071, China
| | - Xiaochen Zhang
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, 300071, China
| | - Kai Li
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, 300071, China
| | - Zhigui Li
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, 300071, China; Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Zhuo Yang
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, 300071, China.
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5
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Rosa P, Catacuzzeno L, Sforna L, Mangino G, Carlomagno S, Mincione G, Petrozza V, Ragona G, Franciolini F, Calogero A. BK channels blockage inhibits hypoxia-induced migration and chemoresistance to cisplatin in human glioblastoma cells. J Cell Physiol 2018; 233:6866-6877. [PMID: 29319175 DOI: 10.1002/jcp.26448] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/05/2018] [Indexed: 12/25/2022]
Abstract
Glioblastoma (GBM) cells express large-conductance, calcium-activated potassium (BK) channels, whose activity is important for several critical aspects of the tumor, such as migration/invasion and cell death. GBMs are also characterized by a heavy hypoxic microenvironment that exacerbates tumor aggressiveness. Since hypoxia modulates the activity of BK channels in many tissues, we hypothesized that a hypoxia-induced modulation of these channels may contribute to the hypoxia-induced GBM aggressiveness. In U87-MG cells, hypoxia induced a functional upregulation of BK channel activity, without interfering with their plasma membrane expression. Wound healing and transwell migration assays showed that hypoxia increased the migratory ability of U87-MG cells, an effect that could be prevented by BK channel inhibition. Toxicological experiments showed that hypoxia was able to induce chemoresistance to cisplatin in U87-MG cells and that the inhibition of BK channels prevented the hypoxia-induced chemoresistance. Clonogenic assays showed that BK channels are also used to increase the clonogenic ability of U87-MG GBM cells in presence, but not in absence, of cisplatin. BK channels were also found to be essential for the hypoxia-induced de-differentiation of GBM cells. Finally, using immunohistochemical analysis, we highlighted the presence of BK channels in hypoxic areas of human GBM tissues, suggesting that our findings may have physiopathological relevance in vivo. In conclusion, our data show that BK channels promote several aspects of the aggressive potential of GBM cells induced by hypoxia, such as migration and chemoresistance to cisplatin, suggesting it as a potential therapeutic target in the treatment of GBM.
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Affiliation(s)
- Paolo Rosa
- Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Polo Pontino, Latina, Italy
| | - Luigi Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Luigi Sforna
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Giorgio Mangino
- Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Polo Pontino, Latina, Italy
| | - Silvia Carlomagno
- Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Polo Pontino, Latina, Italy
| | - Gabriella Mincione
- Department of Medical, Oral and Biotechnological Sciences, University "G. d'Annunzio" Chieti-Pescara, Italy
| | - Vincenzo Petrozza
- Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Polo Pontino, Latina, Italy.,Istituto Chirurgico Ortopedico Traumatologico, ICOT, Latina, Italy
| | - Giuseppe Ragona
- Istituto Chirurgico Ortopedico Traumatologico, ICOT, Latina, Italy.,Department of Experimental Medicine, University of Rome "Sapienza", Rome, Italy
| | - Fabio Franciolini
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Antonella Calogero
- Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Polo Pontino, Latina, Italy.,Istituto Chirurgico Ortopedico Traumatologico, ICOT, Latina, Italy
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6
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Blum-Johnston C, Thorpe RB, Wee C, Opsahl R, Romero M, Murray S, Brunelle A, Blood Q, Wilson R, Blood AB, Zhang L, Longo LD, Pearce WJ, Wilson SM. Long-term hypoxia uncouples Ca 2+ and eNOS in bradykinin-mediated pulmonary arterial relaxation. Am J Physiol Regul Integr Comp Physiol 2018. [PMID: 29513562 DOI: 10.1152/ajpregu.00311.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Bradykinin-induced activation of the pulmonary endothelium triggers a rise in intracellular Ca2+ that activates nitric oxide (NO)-dependent vasorelaxation. Chronic hypoxia is commonly associated with increased pulmonary vascular tone, which can cause pulmonary hypertension in responsive individuals. In the present study, we tested the hypothesis that long-term high-altitude hypoxia (LTH) diminishes bradykinin-induced Ca2+ signals and inhibits endothelial nitric oxide synthase (eNOS), prostacyclin (PGI2), and large-conductance K+ (BKCa) channels in sheep, which are moderately responsive to LTH, resulting in decreased pulmonary arterial vasorelaxation. Pulmonary arteries were isolated from ewes kept near sea level (720 m) or at high altitude (3,801 m) for >100 days. Vessel force was measured with wire myography and endothelial intracellular Ca2+ with confocal microscopy. eNOS was inhibited with 100 μM NG-nitro-l-arginine methyl ester (l-NAME), PGI2 production was inhibited with 10 µM indomethacin that inhibits cyclooxygenase, and BKCa channels were blocked with 1 mM tetraethylammonium. Bradykinin-induced endothelial Ca2+ signals increased following LTH, but bradykinin relaxation decreased. Furthermore, some vessels contracted in response to bradykinin after LTH. l-NAME sensitivity decreased, suggesting that eNOS dysfunction played a role in uncoupling Ca2+ signals and bradykinin relaxation. The Ca2+ ionophore A-23187 (10 µM) elicited an enhanced Ca2+ response following LTH while relaxation was unchanged although l-NAME sensitivity increased. Additionally, BKCa function decreased during bradykinin relaxation following LTH. Western analysis showed that BKCa α-subunit expression was increased by LTH while that for the β1 subunit was unchanged. Overall, these results suggest that those even moderately responsive to LTH can have impaired endothelial function.
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Affiliation(s)
- Carla Blum-Johnston
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine , Loma Linda, California
| | - Richard B Thorpe
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Chelsea Wee
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Raechel Opsahl
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Monica Romero
- Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine , Loma Linda, California
| | - Samuel Murray
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Alexander Brunelle
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Quintin Blood
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Rachael Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Arlin B Blood
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lawrence D Longo
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - William J Pearce
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Sean M Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine , Loma Linda, California
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7
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Tao J, Lan Z, Wang Y, Hei H, Tian L, Pan W, Zhang X, Peng W. Large-Conductance Calcium-Activated Potassium Channels in Glomerulus: From Cell Signal Integration to Disease. Front Physiol 2016; 7:248. [PMID: 27445840 PMCID: PMC4915313 DOI: 10.3389/fphys.2016.00248] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/06/2016] [Indexed: 12/21/2022] Open
Abstract
Large-conductance calcium-activated potassium (BK) channels are currently considered as vital players in a variety of renal physiological processes. In podocytes, BK channels become active in response to stimuli that increase local cytosolic Ca2+, possibly secondary to activation of slit diaphragm TRPC6 channels by chemical or mechanical stimuli. Insulin increases filtration barrier permeability through mobilization of BK channels. In mesangial cells, BK channels co-expressed with β1 subunits act as a major component of the counteractive response to contraction in order to regulate glomerular filtration. This review aims to highlight recent discoveries on the localization, physiological and pathological roles of BK channels in glomerulus.
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Affiliation(s)
- Jie Tao
- Department of Nephrology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Zhen Lan
- Department of Nephrology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Yunman Wang
- Department of Nephrology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Hongya Hei
- Department of Pharmacology, School of Pharmacy, Fudan University Shanghai, China
| | - Lulu Tian
- Department of Pharmacology, School of Pharmacy, Fudan University Shanghai, China
| | - Wanma Pan
- Department of Pharmacology, School of Pharmacy, Fudan University Shanghai, China
| | - Xuemei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University Shanghai, China
| | - Wen Peng
- Department of Nephrology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
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8
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Different expressions of large-conductance Ca2+-activated K+ channels in the mouse renal cortex and hippocampus during postnatal development. Appl Immunohistochem Mol Morphol 2015; 23:146-52. [PMID: 25390352 DOI: 10.1097/pai.0000000000000006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Large-conductance Ca(+)-activated K(+) (BKCa) channels are widely distributed in a variety of cells and play a pivotal and specific role in many pathophysiological conditions. However, the function of BK(Ca) channels in the kidney cortex and hippocampus during the postnatal development has not received attention. In this study, to elucidate the role of BK(Ca) channels during the development, it is essential to establish the location and quantitation of expression of BK(Ca). The expressions of BK(Ca) were detected in the kidney and hippocampus on postnatal days (P) 1, 3, 5, 7, 14, 21, 28, and 49 by immunohistochemical and Western blot analysis. Our results showed that expressions of BK(Ca) channels were found in tubules and corpuscles at all time points. The expression was also observed at all developmental stages of the renal corpuscles, such as comma-shaped body, S-shaped body, renal corpuscles of stage III, and renal corpuscles of stage IV. During the development, the expression of BK(Ca) channels was decreased and the most prominent change of BK(Ca) protein level appeared between P14 and P21. In contrast, BK(Ca) channels were expressed in all regions of the hippocampus at every time point with the level increasing during the early development (P1 to P14). The findings of the present study suggest that BKCa channels play an important role during the postnatal development in both the renal cortex and hippocampus.
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9
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Zhao B, Yang H, Zhang R, Sun H, Liao C, Xu J, Meng K, Jiao J. The role of TRPC6 in oxidative stress-induced podocyte ischemic injury. Biochem Biophys Res Commun 2015; 461:413-20. [PMID: 25896763 DOI: 10.1016/j.bbrc.2015.04.054] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 04/08/2015] [Indexed: 10/23/2022]
Abstract
Increasing evidence suggests that ischemia and hypoxia serve important functions in the development of renal diseases. However, the underlying mechanism of ischemic injury has not been fully understood. In this study, we found that renal ischemia-reperfusion injury induced podocyte effacement and the upregulation of TRPC6 mRNA and protein expression. In in vitro experiments, oxygen glucose deprivation (OGD) treatment enhanced the expression of TRPC6 and TRPC6-dependent Ca(2+) influx. TRPC6 knockdown by siRNA interference attenuated the OGD-induced [Ca(2+)]i and actin assembly. OGD treatment also increased ROS production. Furthermore, inhibition of ROS activity by N-acetyl-l-cysteine (NAC) eliminated the OGD-induced increase in TRPC6 expression and Ca(2+) influx. H2O2 treatment, which results in oxidative stress, also increased TRPC6 expression and Ca(2+) influx. We conclude that TRPC6 upregulation is involved in Ca(2+) signaling and actin reorganization in podocytes after OGD. These findings provide new insight into the mechanisms underlying the cellular response of podocytes to ischemic injury.
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Affiliation(s)
- Bo Zhao
- Department of Nephrology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China; Department of Nephrology, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China
| | - He Yang
- Department of Nephrology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Rui Zhang
- Department of Nephrology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hui Sun
- Department of Emergency, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Chang Liao
- Department of Nephrology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Jia Xu
- Department of Nephrology, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Kexin Meng
- Department of Nephrology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Jundong Jiao
- Department of Nephrology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China; Institute of Nephrology, Harbin Medical University, Harbin, China.
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10
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Sforna L, Cenciarini M, Belia S, D'Adamo MC, Pessia M, Franciolini F, Catacuzzeno L. The role of ion channels in the hypoxia-induced aggressiveness of glioblastoma. Front Cell Neurosci 2015; 8:467. [PMID: 25642170 PMCID: PMC4295544 DOI: 10.3389/fncel.2014.00467] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/24/2014] [Indexed: 12/16/2022] Open
Abstract
The malignancy of glioblastoma multiform (GBM), the most common and aggressive form of human brain tumors, strongly correlates with the presence of hypoxic areas, but the mechanisms controlling the hypoxia-induced aggressiveness are still unclear. GBM cells express a number of ion channels whose activity supports cell volume changes and increases in the cytosolic Ca2+ concentration, ultimately leading to cell proliferation, migration or death. In several cell types it has previously been shown that low oxygen levels regulate the expression and activity of these channels, and more recent data indicate that this also occurs in GBM cells. Based on these findings, it may be hypothesized that the modulation of ion channel activity or expression by the hypoxic environment may participate in the acquisition of the aggressive phenotype observed in GBM cells residing in a hypoxic environment. If this hypothesis will be confirmed, the use of available ion channels modulators may be considered for implementing novel therapeutic strategies against these tumors.
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Affiliation(s)
- Luigi Sforna
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
| | - Marta Cenciarini
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
| | - Silvia Belia
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
| | - Maria Cristina D'Adamo
- Faculty of Medicine, Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Mauro Pessia
- Faculty of Medicine, Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Fabio Franciolini
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
| | - Luigi Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
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11
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Xie H, Zhang YQ, Pan XL, Wu SH, Chen X, Wang J, Liu H, Qian XZ, Liu ZG, Liu LJ. Decreased calcium-activated potassium channels by hypoxia causes abnormal firing in the spontaneous firing medial vestibular nuclei neurons. Eur Arch Otorhinolaryngol 2014; 272:2703-11. [PMID: 25173490 DOI: 10.1007/s00405-014-3158-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 06/15/2014] [Indexed: 12/20/2022]
Abstract
Vertebrobasilar insufficiency (VBI) presents complex varied clinical symptoms, including vertigo and hearing loss. Little is known, however, about how Ca(2+)-activated K(+) channel attributes to the medial vestibular nucleus (MVN) neural activity in VBI. To address this issue, we performed whole-cell patch clamp and quantitative polymerase chain reaction (qPCR) to examine the effects of hypoxia on neural activity and the changes of the large conductance Ca(2+) activated K(+) channels (BKCa channels) in the MVN neurons in brain slices of male C57BL/6 mice. Brief hypoxic stimuli of the brain slices containing MVN were administrated by switching the normoxic artificial cerebrospinal fluid (ACSF) equilibrated with 21% O2/5% CO2 to hypoxic ACSF equilibrated with 5% O2/5% CO2 (balance N2). 3-min hypoxia caused a depolarization in the resting membrane potential (RM) in 8/11 non-spontaneous firing MVN neurons. 60/72 spontaneous firing MVN neurons showed a dramatic increase in firing frequency and a depolarization in the RM following brief hypoxia. The amplitude of the afterhyperpolarization (AHPA) was significantly decreased in both type A and type B spontaneous firing MVN neurons. Hypoxia-induced firing response was alleviated by pretreatment with NS1619, a selective BKCa activator. Furthermore, brief hypoxia caused a decrease in the amplitude of iberiotoxin-sensitive outward currents and mRNA level of BKCa in MVN neurons. These results suggest that BKCa channels protect against abnormal MVN neuronal activity induced by hypoxia, and might be a key target for treatment of vertigo and hearing loss in VBI.
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Affiliation(s)
- Hong Xie
- Jingzhou Central Hospital, Jingzhou, 434020, People's Republic of China,
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12
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Prasad M, Zachar V, Fink T, Pennisi CP. Moderate hypoxia influences potassium outward currents in adipose-derived stem cells. PLoS One 2014; 9:e104912. [PMID: 25115627 PMCID: PMC4130641 DOI: 10.1371/journal.pone.0104912] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/15/2014] [Indexed: 01/23/2023] Open
Abstract
Moderate hypoxic preconditioning of adipose-derived stem cells (ASCs) enhances properties such as proliferation and secretion of growth factors, representing a valuable strategy to increase the efficiency of cell-based therapies. In a wide variety of cells potassium (K+) channels are key elements involved in the cellular responses to hypoxia, suggesting that ASCs cultured under low oxygen conditions may display altered electrophysiological properties. Here, the effects of moderate hypoxic culture on proliferation, whole-cell currents, and ion channel expression were investigated using human ASCs cultured at 5% and 20% oxygen. Although cell proliferation was greatly enhanced, the dose-dependent growth inhibition by the K+ channel blocker tetraethylammonium (TEA) was not significantly affected by hypoxia. Under both normoxic and hypoxic conditions, ASCs displayed outward K+ currents composed by Ca2+-activated, delayed rectifier, and transient components. Hypoxic culture reduced the slope of the current-voltage curves and caused a negative shift in the voltage activation threshold of the whole-cell currents. However, the TEA-mediated shift of voltage activation threshold was not affected by hypoxia. Semiquantitative real-time RT-PCR revealed that expression of genes encoding for various ion channels subunits related to oxygen sensing and proliferation remained unchanged after hypoxic culture. In conclusion, outward currents are influenced by moderate hypoxia in ASCs through a mechanism that is not likely the result of modulation of TEA-sensitive K+ channels.
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Affiliation(s)
- Mayuri Prasad
- Laboratory for Stem Cell Research, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Vladimir Zachar
- Laboratory for Stem Cell Research, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Trine Fink
- Laboratory for Stem Cell Research, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Cristian Pablo Pennisi
- Laboratory for Stem Cell Research, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
- * E-mail:
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Wen D, Cornelius RJ, Sansom SC. Interacting influence of diuretics and diet on BK channel-regulated K homeostasis. Curr Opin Pharmacol 2013; 15:28-32. [PMID: 24721651 DOI: 10.1016/j.coph.2013.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/04/2013] [Indexed: 12/26/2022]
Abstract
Large conductance, Ca-activated K channels (BK) are abundantly located in cells of vasculature, glomerulus, and distal nephron, where they are involved in maintaining blood volume, blood pressure, and K homeostasis. In mesangial cells and smooth muscle cells of vessels, the BK-α pore associates with BK-β1 subunits and regulates contraction in a Ca-mediated feedback manner. The BK-β1 also resides in connecting tubule cells of the nephron. BK-β1 knockout mice (β1KO) exhibit fluid retention, hypertension, and compromised K handling. The BK-α/β4 resides in acid/base transporting intercalated cells (IC) of the distal nephron, where they mediate K secretion in mammals on a high K, alkaline diet. BK-α expression in IC is increased by a high K diet via aldosterone. The BK-β4 subunit and alkaline urine are necessary for the luminal expression and function of BK-α in mouse IC. In distal nephron cells, membrane BK-α expression is inhibited by WNK4 in in vitro expression systems, indicating a role in the hyperkalemic phenotype in patients with familial hyperkalemic hypertension type 2 (FHHt2). β1KO and BK-β4 knockout mice (β4KO) are hypertensive because of exaggerated epithelial Na channels (ENaC) mediated Na retention in an effort to secrete K via only renal outer medullary K channels (ROMK). BK hypertension is resistant to thiazides and furosemide, and would be more amenable to ENaC and aldosterone inhibiting drugs. Activators of BK-α/β1 or BK-α/β4 might be effective blood pressure lowering agents for a subset of hypertensive patients. Inhibitors of renal BK would effectively spare K in patients with Bartter Syndrome, a renal K wasting disease.
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Affiliation(s)
- Donghai Wen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Ryan J Cornelius
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Steven C Sansom
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States.
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Yang H, Zhao B, Liao C, Zhang R, Meng K, Xu J, Jiao J. High glucose-induced apoptosis in cultured podocytes involves TRPC6-dependent calcium entry via the RhoA/ROCK pathway. Biochem Biophys Res Commun 2013; 434:394-400. [PMID: 23570668 DOI: 10.1016/j.bbrc.2013.03.087] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 03/29/2013] [Indexed: 10/27/2022]
Abstract
Increasing evidence indicates that podocyte apoptosis is a key event in the development of diabetic nephrology. However, the underlying mechanism of this apoptosis remains poorly understood. In this study, we report that high levels of glucose enhanced the expression of TRPC6 and TRPC6-dependent Ca(2+) influx, but glucose levels did not affect TRPC1 and TRPC5 expression. TRPC6 knockdown by siRNA interference attenuated the observed increase in glucose-induced podocyte apoptosis. High glucose levels also increased the generation of ROS; inhibition of ROS activity by N-acetyl-l-cysteine attenuated the high glucose-induced increase in TRPC6 expression and Ca(2+) influx. Exogenous treatment with H2O2 mimicked the high glucose response, resulting in an increase in TRPC6 expression and Ca(2+) influx. Taken together, these data suggest that high glucose levels induce ROS, thereby mediating TRPC6 expression and Ca(2+) influx. Because RhoA activity is increased following TRPC6 activation, we investigated whether TRPC6 is involved in high glucose-induced apoptosis via the RhoA/ROCK pathway. We report that high glucose levels produced an increase in RhoA activity, and this effect was abolished by the knockdown of TRPC6. Moreover, inhibition of the RhoA/ROCK pathway by a ROCK inhibitor, Y27632, also attenuated high glucose-induced apoptosis. We conclude that TRPC6 is involved in high glucose-induced podocyte apoptosis through the RhoA/ROCK pathway.
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Affiliation(s)
- He Yang
- Department of Nephrology, The Second Affiliated Hospital, Harbin Medical University, PR China
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Thorpe RB, Stockman SL, Williams JM, Lincoln TM, Pearce WJ. Hypoxic depression of PKG-mediated inhibition of serotonergic contraction in ovine carotid arteries. Am J Physiol Regul Integr Comp Physiol 2013; 304:R734-43. [PMID: 23447135 DOI: 10.1152/ajpregu.00212.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chronic hypoxia attenuates soluble guanylate cyclase-induced vasorelaxation in serotonin (5-HT)-contracted ovine carotid arteries. Because protein kinase G (PKG) mediates many effects of soluble guanylate cyclase activation through phosphorylation of multiple kinase targets in vascular smooth muscle, we tested the hypothesis that chronic hypoxia reduces the ability of PKG to phosphorylate its target proteins, which attenuates the ability of PKG to induce vasorelaxation. We also tested the hypothesis that hypoxia attenuates PKG expression and/or activity. Arteries from normoxic and chronically hypoxic (altitude of 3,820 m for 110 days) fetal and adult sheep were denuded of endothelium and equilibrated with 95% O2-5% CO2 in the presence of nitro-l-arginine methyl ester (l-NAME) and N(G)-nitro-l-arginine (l-NNA) to inhibit residual endothelial nitric oxide synthase. Concentration-response relations for 5-HT were determined in the presence of prazosin to minimize activation of α-adrenergic receptors. The PKG activator 8-(p-chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (8-pCTP-cGMP) reduced agonist binding affinity of the 5-HT receptor in a concentration-dependent manner that was attenuated by hypoxia. Expression and activity of PKG-I was not significantly affected by chronic hypoxia in either fetal or adult arteries, although PKG-I abundance was greater in fetal arteries. Pretreatment with the large conductance calcium-sensitive potassium channel (BK) inhibitor iberiotoxin attenuated the vasorelaxation induced by 8-pCPT-cGMP in normoxic but not chronically hypoxic arteries. These results support the hypothesis that hypoxia attenuates the vasorelaxant effects of PKG through suppression of the ability of PKG to activate large conductance calcium-sensitive potassium channels in arterial smooth muscle. The results also reveal that this hypoxic effect is greater in fetal than adult arteries and that chronic maternal hypoxia can profoundly affect fetal vascular function.
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Affiliation(s)
- Richard B Thorpe
- Divisions of Physiology, Pharmacology, and Biochemistry, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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