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Xue Q, Yang Y, Li H, Li X, Zou L, Li T, Ma H, Qi H, Wang J, Yu T. Functions and mechanisms of protein lysine butyrylation (Kbu): Therapeutic implications in human diseases. Genes Dis 2023; 10:2479-2490. [PMID: 37554202 PMCID: PMC10404885 DOI: 10.1016/j.gendis.2022.10.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 09/27/2022] [Accepted: 10/20/2022] [Indexed: 11/30/2022] Open
Abstract
Post-translational modifications (PTM) are covalent modifications of proteins or peptides caused by proteolytic cleavage or the attachment of moieties to one or more amino acids. PTMs play essential roles in biological function and regulation and have been linked with several diseases. Modifications of protein acylation (Kac), a type of PTM, are known to induce epigenetic regulatory processes that promote various diseases. Thus, an increasing number of studies focusing on acylation modifications are being undertaken. Butyrylation (Kbu) is a new acylation process found in animals and plants. Kbu has been recently linked to the onset and progression of several diseases, such as cancer, cardiovascular diseases, diabetes, and vascular dementia. Moreover, the mode of action of certain drugs used in the treatment of lymphoma and colon cancer is based on the regulation of butyrylation levels, suggesting that butyrylation may play a therapeutic role in these diseases. In addition, butyrylation is also commonly involved in rice gene expression and thus plays an important role in the growth, development, and metabolism of rice. The tools and analytical methods that could be utilized for the prediction and detection of lysine butyrylation have also been investigated. This study reviews the potential role of histone Kbu, as well as the mechanisms underlying this process. It also summarizes various enzymes and analytical methods associated with Kbu, with the goal of providing new insights into the role of Kbu in gene regulation and diseases.
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Affiliation(s)
- Qianqian Xue
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Yanyan Yang
- Department of Immunology, School of Basic Medicine, Qingdao University, Qingdao, Shandong 266021, China
| | - Hong Li
- Clinical Laboratory, Central Laboratory. The Affiliated Qingdao Hiser Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Xiaoxin Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Lu Zou
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Tianxiang Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Huibo Ma
- Department of Vascular Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Hongzhao Qi
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
| | - Jianxun Wang
- Department of Immunology, School of Basic Medicine, Qingdao University, Qingdao, Shandong 266021, China
| | - Tao Yu
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, China
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Yang D, Chen M, Yang S, Deng F, Guo X. Connexin hemichannels and pannexin channels in toxicity: Recent advances and mechanistic insights. Toxicology 2023; 488:153488. [PMID: 36918108 DOI: 10.1016/j.tox.2023.153488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 03/14/2023]
Abstract
Connexin hemichannels and pannexin channels are two types of transmembrane channels that allow autocrine/paracrine signalling through the exchange of ions and molecules between the intra- and extracellular compartments. However, owing to the poor selectivity of permeable ions and metabolites, the massive opening of these plasma membrane channels can lead to an excessive influx of toxic substances and an outflux of essential metabolites, such as adenosine triphosphate, glutathione, glutamate and ions, resulting in unbalanced cell homeostasis and impaired cell function. It is becoming increasingly clear that these channels can be activated in response to external stimuli and are involved in toxicity, yet their concrete mechanistic roles in the toxic effects induced by stress and various environmental changes remain poorly defined. This review provides an updated understanding of connexin hemichannels and pannexin channels in response to multiple extrinsic stressors and how these activated channels and their permeable messengers participate in toxicological pathways and processes, including inflammation, oxidative damage, intracellular calcium imbalance, bystander DNA damage and excitotoxicity.
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Affiliation(s)
- Di Yang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Mengyuan Chen
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Sijia Yang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Furong Deng
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Xinbiao Guo
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China.
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Omolaoye TS, Jalaleddine N, Cardona Maya WD, du Plessis SS. Mechanisms of SARS-CoV-2 and Male Infertility: Could Connexin and Pannexin Play a Role? Front Physiol 2022; 13:866675. [PMID: 35721552 PMCID: PMC9205395 DOI: 10.3389/fphys.2022.866675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on male infertility has lately received significant attention. SARS-CoV-2, the virus that causes coronavirus disease (COVID-19) in humans, has been shown to impose adverse effects on both the structural components and function of the testis, which potentially impact spermatogenesis. These adverse effects are partially explained by fever, systemic inflammation, oxidative stress, and an increased immune response leading to impaired blood-testis barrier. It has been well established that efficient cellular communication via gap junctions or functional channels is required for tissue homeostasis. Connexins and pannexins are two protein families that mediate autocrine and paracrine signaling between the cells and the extracellular environment. These channel-forming proteins have been shown to play a role in coordinating cellular communication in the testis and epididymis. Despite their role in maintaining a proper male reproductive milieu, their function is disrupted under pathological conditions. The involvement of these channels has been well documented in several physiological and pathological conditions and their designated function in infectious diseases. However, their role in COVID-19 and their meaningful contribution to male infertility remains to be elucidated. Therefore, this review highlights the multivariate pathophysiological mechanisms of SARS-CoV-2 involvement in male reproduction. It also aims to shed light on the role of connexin and pannexin channels in disease progression, emphasizing their unexplored role and regulation of SARS-CoV-2 pathophysiology. Finally, we hypothesize the possible involvement of connexins and pannexins in SARS-CoV-2 inducing male infertility to assist future research ideas targeting therapeutic approaches.
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Affiliation(s)
- Temidayo S. Omolaoye
- Department of Basic Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Nour Jalaleddine
- Department of Basic Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Walter D. Cardona Maya
- Reproduction Group, Department of Microbiology and Parasitology, Faculty of Medicine, Universidad de Antioquia, Medellin, Colombia
| | - Stefan S. du Plessis
- Department of Basic Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
- Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
- *Correspondence: Stefan S. du Plessis,
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Wang B, Wan L, Sun P, Zhang L, Han L, Zhang H, Zhang J, Pu Y, Zhu B. Associations of genetic variation in E3 SUMO-protein ligase CBX4 with noise-induced hearing loss. Hum Mol Genet 2022; 31:2109-2120. [PMID: 35038734 DOI: 10.1093/hmg/ddac006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 01/02/2022] [Accepted: 01/06/2022] [Indexed: 11/14/2022] Open
Abstract
Noise-induced hearing loss (NIHL) is a multifactorial disease caused by environmental, genetic, and epigenetic variables. SUMOylation is a post-translational modification that regulates biological processes. The objective of this study was to determine the link between genetic variation in the CBX4 and the risk of NIHL. This study applied a case-control design with 588 cases and 582 controls, and the sample was predominantly male (93.76%). The T allele of CBX4 rs1285250 was found to be significantly linked with NIHL (p = 0.002) and showed strong associations in both the codominant and recessive models (TT vs CC, p = 0.005; TT/TC vs CC, p = 0.009). By constructing a mouse model of hearing loss due to noise exposure, changes in hearing thresholds were observed in noise-exposed mice, along with a decrease in the number of cochlear hair cells. Furthermore, noise promotes cochlear hair cell apoptosis by inducing SP1/CBX4 pathway activation. Further functional studies demonstrated that SP1 has an influence on the promoter activity of the CBX4 rs1285250 intron, with the promoter activity of the T allele being higher than that of the C allele. Knockdown of transcription factor SP1 reduced the expression of CBX4 expression and simultaneously reduced apoptosis in HEI-OC1 cells. Together, our findings have shown that CBX4 genetic polymorphism rs1285250 T-allele was associated with increased risk of NIHL and might be used as biomarkers for male workers exposed to noise. Furthermore, we speculate that the CBX4 of rs1285250 T-allele leads to a stronger potential enhancer activity from a predicted gain of stronger SP1 binding.
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Affiliation(s)
- Boshen Wang
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Department of Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, Jiangsu, China
| | - Liu Wan
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Department of Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, Jiangsu, China
| | - Peng Sun
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Department of Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, Jiangsu, China
| | - Ludi Zhang
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Department of Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, Jiangsu, China
| | - Lei Han
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Jiangsu Preventive Medicine Association, Nanjing 210009, Jiangsu, China
| | - Hengdong Zhang
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Jiangsu Preventive Medicine Association, Nanjing 210009, Jiangsu, China
| | - Juan Zhang
- Department of Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, Jiangsu, China
| | - Yuepu Pu
- Department of Key Laboratory of Environmental Medicine Engineering of Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, Jiangsu, China
| | - Baoli Zhu
- Department of Prevention and Control for Occupational Disease, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, Jiangsu, China
- Jiangsu Preventive Medicine Association, Nanjing 210009, Jiangsu, China
- Department of Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing 210000, Jiangsu, China
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Ouabain Enhances Gap Junctional Intercellular Communication by Inducing Paracrine Secretion of Prostaglandin E2. Int J Mol Sci 2021; 22:ijms22126244. [PMID: 34200582 PMCID: PMC8230150 DOI: 10.3390/ijms22126244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 12/27/2022] Open
Abstract
Ouabain is a cardiac glycoside that has been described as a hormone, with interesting effects on epithelial physiology. We have shown previously that ouabain induces gap junctional intercellular communication (GJIC) in wild, sensitive cells (MDCK-S), but not in cells that have become insensitive (MDCK-I) by modifying their Na+-K+-ATPase. We have also demonstrated that prostaglandin E2 (PGE2) is able to induce increased GJIC by a mechanism other than ouabain, that does not depend on Na+-K+-ATPase. In this work we show, by dye transfer assays, that when MDCK-S and MDCK-I are randomly mixed, to form monolayers, the latter stablish GJIC, because of stimulation by a compound released to the extracellular media, by MDCK-S cells, after treatment with ouabain, as evidenced by the fact that monolayers of only MDCK-I cells, treated with a conditioned medium (CM) that is obtained after incubation of MDCK-S monolayers with ouabain, significantly increase their GJIC. The further finding that either (1) pre-treatment with COX-2 inhibitors or (2) addition to CM of antagonists of EP2 receptor abolish CM's ability to induce GJIC in MDCK-I monolayers indicate that PGE2 is the GJIC-inducing compound. Therefore, these results indicate that, in addition to direct stimulation, mediated by Na+-K+-ATPase, ouabain enhances GJIC indirectly through the paracrine production of PGE2.
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Soh GB, Tchitnga R, Woafo P. Long-range interaction effects on coupled excitable nodes: traveling waves and chimera state. Heliyon 2021; 7:e07026. [PMID: 34036198 PMCID: PMC8134981 DOI: 10.1016/j.heliyon.2021.e07026] [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: 12/21/2020] [Revised: 02/21/2021] [Accepted: 05/05/2021] [Indexed: 11/30/2022] Open
Abstract
In this paper, analytical and numerical studies of the influence of the long-range interaction parameter on the excitability threshold in a ring of FitzHugh-Nagumo (FHN) system are investigated. The long-range interaction is introduced to the network to model regulation of the Gap junctions or hemichannels activity at the connexins level, which provides links between pre-synaptic and post-synaptic neurons. Results show that the long-range coupling enhances the range of the threshold parameter. We also investigate the long-range effects on the network dynamics, which induces enlargement of the oscillatory zone before the excitable regime. When considering bidirectional coupling, the long-range interaction induces traveling patterns such as traveling waves, while when considering unidirectional coupling, the long-range interaction induces multi-chimera states. We also studied the difference between the dynamics of coupled oscillators and coupled excitable neurons. We found that, for the coupled system, the oscillation period decreases with the increasing of the coupling parameter. For the same values of the coupling parameter, the oscillation period of the Oscillatory dynamics is greater than the oscillation period of the excitable dynamics. The analytical approximation shows good agreement with the numerical results.
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Affiliation(s)
- Guy Blondeau Soh
- Laboratory of Electronics, Automation and Signal Processing, Faculty of Science, Department of Physics, University of Dschang, P.O. Box 67, Dschang, Cameroon
| | - Robert Tchitnga
- Laboratory of Electronics, Automation and Signal Processing, Faculty of Science, Department of Physics, University of Dschang, P.O. Box 67, Dschang, Cameroon.,Institute of Surface Chemistry and Catalysis, University of Ulm, Albert-Einstein-Allee 47, 89081 Ulm, Germany
| | - Paul Woafo
- Laboratory of Modeling and Simulation in Engineering, Biomimetics and Prototypes, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon
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Marsh SR, Williams ZJ, Pridham KJ, Gourdie RG. Peptidic Connexin43 Therapeutics in Cardiac Reparative Medicine. J Cardiovasc Dev Dis 2021; 8:52. [PMID: 34063001 PMCID: PMC8147937 DOI: 10.3390/jcdd8050052] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/19/2021] [Accepted: 05/01/2021] [Indexed: 12/12/2022] Open
Abstract
Connexin (Cx43)-formed channels have been linked to cardiac arrhythmias and diseases of the heart associated with myocardial tissue loss and fibrosis. These pathologies include ischemic heart disease, ischemia-reperfusion injury, heart failure, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and Duchenne muscular dystrophy. A number of Cx43 mimetic peptides have been reported as therapeutic candidates for targeting disease processes linked to Cx43, including some that have advanced to clinical testing in humans. These peptides include Cx43 sequences based on the extracellular loop domains (e.g., Gap26, Gap 27, and Peptide5), cytoplasmic-loop domain (Gap19 and L2), and cytoplasmic carboxyl-terminal domain (e.g., JM2, Cx43tat, CycliCX, and the alphaCT family of peptides) of this transmembrane protein. Additionally, RYYN peptides binding to the Cx43 carboxyl-terminus have been described. In this review, we survey preclinical and clinical data available on short mimetic peptides based on, or directly targeting, Cx43, with focus on their potential for treating heart disease. We also discuss problems that have caused reluctance within the pharmaceutical industry to translate peptidic therapeutics to the clinic, even when supporting preclinical data is strong. These issues include those associated with the administration, stability in vivo, and tissue penetration of peptide-based therapeutics. Finally, we discuss novel drug delivery technologies including nanoparticles, exosomes, and other nanovesicular carriers that could transform the clinical and commercial viability of Cx43-targeting peptides in treatment of heart disease, stroke, cancer, and other indications requiring oral or parenteral administration. Some of these newly emerging approaches to drug delivery may provide a path to overcoming pitfalls associated with the drugging of peptide therapeutics.
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Affiliation(s)
- Spencer R. Marsh
- Fralin Biomedical Research Institute at VTC, Virginia Tech, Roanoke, VA 24016, USA; (S.R.M.); (Z.J.W.); (K.J.P.)
- Center for Heart and Reparative Medicine Research, Virginia Tech, Roanoke, VA 24016, USA
| | - Zachary J. Williams
- Fralin Biomedical Research Institute at VTC, Virginia Tech, Roanoke, VA 24016, USA; (S.R.M.); (Z.J.W.); (K.J.P.)
- Center for Heart and Reparative Medicine Research, Virginia Tech, Roanoke, VA 24016, USA
- Translational Biology Medicine and Health Graduate Program, Virginia Tech, Roanoke, VA 24016, USA
| | - Kevin J. Pridham
- Fralin Biomedical Research Institute at VTC, Virginia Tech, Roanoke, VA 24016, USA; (S.R.M.); (Z.J.W.); (K.J.P.)
- Center for Heart and Reparative Medicine Research, Virginia Tech, Roanoke, VA 24016, USA
| | - Robert G. Gourdie
- Fralin Biomedical Research Institute at VTC, Virginia Tech, Roanoke, VA 24016, USA; (S.R.M.); (Z.J.W.); (K.J.P.)
- Center for Heart and Reparative Medicine Research, Virginia Tech, Roanoke, VA 24016, USA
- Translational Biology Medicine and Health Graduate Program, Virginia Tech, Roanoke, VA 24016, USA
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
- Department of Emergency Medicine, Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, VA 24016, USA
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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Identification and classification of innexin gene transcripts in the central nervous system of the terrestrial slug Limax valentianus. PLoS One 2021; 16:e0244902. [PMID: 33857131 PMCID: PMC8049302 DOI: 10.1371/journal.pone.0244902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 03/09/2021] [Indexed: 12/20/2022] Open
Abstract
Intercellular gap junction channels and single-membrane channels have been reported to regulate electrical synapse and the brain function. Innexin is known as a gap junction-related protein in invertebrates and is involved in the formation of intercellular gap junction channels and single-cell membrane channels. Multiple isoforms of innexin protein in each species enable the precise regulation of channel function. In molluscan species, sequence information of innexins is still limited and the sequences of multiple innexin isoforms have not been classified. This study examined the innexin transcripts expressed in the central nervous system of the terrestrial slug Limax valentianus and identified 16 transcripts of 12 innexin isoforms, including the splicing variants. We performed phylogenetic analysis and classified the isoforms with other molluscan innexin sequences. Next, the phosphorylation, N-glycosylation, and S-nitrosylation sites were predicted to characterize the innexin isoforms. Further, we identified 16 circular RNA sequences of nine innexin isoforms in the central nervous system of Limax. The identification and classification of molluscan innexin isoforms provided novel insights for understanding the regulatory mechanism of innexin in this phylum.
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Van Campenhout R, Gomes AR, De Groof TW, Muyldermans S, Devoogdt N, Vinken M. Mechanisms Underlying Connexin Hemichannel Activation in Disease. Int J Mol Sci 2021; 22:ijms22073503. [PMID: 33800706 PMCID: PMC8036530 DOI: 10.3390/ijms22073503] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 03/22/2021] [Accepted: 03/26/2021] [Indexed: 02/07/2023] Open
Abstract
Gap junctions and connexin hemichannels mediate intercellular and extracellular communication, respectively. While gap junctions are seen as the “good guys” by controlling homeostasis, connexin hemichannels are considered as the “bad guys”, as their activation is associated with the onset and dissemination of disease. Open connexin hemichannels indeed mediate the transport of messengers between the cytosol and extracellular environment and, by doing so, fuel inflammation and cell death in a plethora of diseases. The present mini-review discusses the mechanisms involved in the activation of connexin hemichannels during pathology.
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Affiliation(s)
- Raf Van Campenhout
- Department of Pharmaceutical and Pharmacological Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (R.V.C.); (A.R.G.)
| | - Ana Rita Gomes
- Department of Pharmaceutical and Pharmacological Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (R.V.C.); (A.R.G.)
| | - Timo W.M. De Groof
- Department of Medical Imaging, In Vivo Cellular and Molecular Imaging Laboratory, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (T.W.M.D.G.); (N.D.)
| | - Serge Muyldermans
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium;
| | - Nick Devoogdt
- Department of Medical Imaging, In Vivo Cellular and Molecular Imaging Laboratory, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (T.W.M.D.G.); (N.D.)
| | - Mathieu Vinken
- Department of Pharmaceutical and Pharmacological Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (R.V.C.); (A.R.G.)
- Correspondence: ; Tel.: +32-2-4774587
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Apocynin Treatment Prevents Cardiac Connexin 43 Hemichannels Hyperactivity by Reducing Nitroso-Redox Stress in Mdx Mice. Int J Mol Sci 2020; 21:ijms21155415. [PMID: 32751416 PMCID: PMC7432655 DOI: 10.3390/ijms21155415] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 07/10/2020] [Accepted: 07/17/2020] [Indexed: 12/16/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a fatal disease that causes cardiomyopathy and is associated with oxidative stress. In the heart, oxidative stress interferes with the location of connexin 43 (Cx43) to the intercalated discs causing its lateralization to the plasma membrane where Cx43 forms hemichannels. We tested the hypothesis that in DMD cardiomyopathy, increased oxidative stress is associated with the formation and activation of Cx43 hemichannels. For this, we used mdx mice as a DMD model and evaluated cardiac function, nitroso-redox changes and Cx43 hemichannels permeability. Mdx hearts presented increased NADPH oxidase-derived oxidative stress and increased Cx43 S-nitrosylation compared to controls. These redox changes were associated with increased Cx43 lateralization, decreased cardiac contractility and increased arrhythmic events. Pharmacological inhibition of NADPH oxidase using apocynin (one month) reduced systemic oxidative stress and reversed the aforementioned changes towards normal, except Cx43 lateralization. Opening of Cx43 hemichannels was blocked by apocynin treatment and by acute hemichannel blockade with carbenoxolone. NADPH oxidase inhibition also prevented the occurrence of apoptosis in mdx hearts and reversed the ventricular remodeling. These results show that NADPH oxidase activity in DMD is associated with S-nitrosylation and opening of Cx43 hemichannels. These changes lead to apoptosis and cardiac dysfunction and were prevented by NADPH oxidase inhibition.
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12
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Abstract
Of the 21 members of the connexin family, 4 (Cx37, Cx40, Cx43, and Cx45) are expressed in the endothelium and/or smooth muscle of intact blood vessels to a variable and dynamically regulated degree. Full-length connexins oligomerize and form channel structures connecting the cytosol of adjacent cells (gap junctions) or the cytosol with the extracellular space (hemichannels). The different connexins vary mainly with regard to length and sequence of their cytosolic COOH-terminal tails. These COOH-terminal parts, which in the case of Cx43 are also translated as independent short isoforms, are involved in various cellular signaling cascades and regulate cell functions. This review focuses on channel-dependent and -independent effects of connexins in vascular cells. Channels play an essential role in coordinating and synchronizing endothelial and smooth muscle activity and in their interplay, in the control of vasomotor actions of blood vessels including endothelial cell reactivity to agonist stimulation, nitric oxide-dependent dilation, and endothelial-derived hyperpolarizing factor-type responses. Further channel-dependent and -independent roles of connexins in blood vessel function range from basic processes of vascular remodeling and angiogenesis to vascular permeability and interactions with leukocytes with the vessel wall. Together, these connexin functions constitute an often underestimated basis for the enormous plasticity of vascular morphology and function enabling the required dynamic adaptation of the vascular system to varying tissue demands.
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Affiliation(s)
- Ulrich Pohl
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany; Biomedical Centre, Cardiovascular Physiology, LMU Munich, Planegg-Martinsried, Germany; German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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13
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Muñoz P, Ardiles ÁO, Pérez-Espinosa B, Núñez-Espinosa C, Paula-Lima A, González-Billault C, Espinosa-Parrilla Y. Redox modifications in synaptic components as biomarkers of cognitive status, in brain aging and disease. Mech Ageing Dev 2020; 189:111250. [PMID: 32433996 DOI: 10.1016/j.mad.2020.111250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/05/2020] [Accepted: 04/10/2020] [Indexed: 02/06/2023]
Abstract
Aging is a natural process that includes several changes that gradually make organisms degenerate and die. Harman's theory proposes that aging is a consequence of the progressive accumulation of oxidative modifications mediated by reactive oxygen/nitrogen species, which plays an essential role in the development and progression of many neurodegenerative diseases. This review will focus on how abnormal redox modifications induced by age impair the functionality of neuronal redox-sensitive proteins involved in axonal elongation and guidance, synaptic plasticity, and intercellular communication. We will discuss post-transcriptional regulation of gene expression by microRNAs as a mechanism that controls the neuronal redox state. Finally, we will discuss how some brain-permeant antioxidants from the diet have a beneficial effect on cognition. Taken together, the evidence revised here indicates that oxidative-driven modifications of specific proteins and changes in microRNA expression may be useful biomarkers for aging and neurodegenerative diseases. Also, some specific antioxidant therapies have undoubtedly beneficial neuroprotective effects when administered in the correct doses, in the ideal formulation combination, and during the appropriate therapeutic window. The use of some antioxidants is, therefore, still poorly explored for the treatment of neurodegenerative diseases such as Alzheimer's disease.
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Affiliation(s)
- Pablo Muñoz
- Department of Pathology and Physiology, Medical School, Faculty of Medicine, Universidad de Valparaíso, Valparaíso, Chile; Translational Neurology Center, Faculty of Medicine, Universidad de Valparaíso, Valparaíso, Chile; Biomedical Research Center, Universidad de Valparaíso, Valparaíso, Chile; Thematic Task Force on Healthy Aging, CUECH Research Network.
| | - Álvaro O Ardiles
- Department of Pathology and Physiology, Medical School, Faculty of Medicine, Universidad de Valparaíso, Valparaíso, Chile; Translational Neurology Center, Faculty of Medicine, Universidad de Valparaíso, Valparaíso, Chile; Thematic Task Force on Healthy Aging, CUECH Research Network; Interdisciplinary Center of Neuroscience of Valparaíso, Universidad de Valparaíso, Valparaíso, Chile; Interdisciplinary Center for Health Studies, Universidad de Valparaíso, Valparaíso, Chile
| | - Boris Pérez-Espinosa
- Thematic Task Force on Healthy Aging, CUECH Research Network; Laboratorio biología de la Reproduccion, Departamento Biomédico, Facultad Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Cristian Núñez-Espinosa
- Thematic Task Force on Healthy Aging, CUECH Research Network; School of Medicine, Universidad de Magallanes, Punta Arenas, Chile
| | - Andrea Paula-Lima
- Thematic Task Force on Healthy Aging, CUECH Research Network; Institute for Research in Dental Sciences, Faculty of Dentistry; Universidad de Chile, Santiago, Chile; Biomedical Neuroscience Institute (BNI) and Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Christian González-Billault
- Thematic Task Force on Healthy Aging, CUECH Research Network; Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; FONDAP Geroscience Center for Brain Health and Metabolism, Santiago, Chile; Buck Institute for Research on Aging, Novato, CA, USA.
| | - Yolanda Espinosa-Parrilla
- Thematic Task Force on Healthy Aging, CUECH Research Network; School of Medicine, Universidad de Magallanes, Punta Arenas, Chile; Laboratory of Molecular Medicine - LMM, Center for Education, Healthcare and Investigation - CADI, University of Magallanes, Punta Arenas, Chile.
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14
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Liu X, Liu R, Bai Y, Jiang H, Fu X, Ma S. Post-translational modifications of protein in response to ionizing radiation. Cell Biochem Funct 2020; 38:283-289. [PMID: 31943290 DOI: 10.1002/cbf.3467] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 11/11/2019] [Indexed: 12/23/2022]
Abstract
Based on central dogma of genetics, protein is the embodiment and executor of genetic function, post-translational modifications (PTMs) of protein are particularly important and involved in almost all aspects of cell biology and pathogenesis. Studies have shown that ionizing radiation (IR) alters gene expression much more profoundly and a broad variety of cell-process pathways, lots of proteins are modified and activated. Our understanding of the protein in response to ionizing radiation is steadily increasing. Among the various biological processes known to induce radioresistance, PTMs have attracted marked attention in recent years. The present review summarizes the latest knowledge about how PTMs response to ionizing radiation and pathway analysis were conducted. The data provided insights into biological effects of IR and contributing to the development of novel IR-based strategies.
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Affiliation(s)
- Xiaodong Liu
- School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China.,NHC Key lab of Radiation Biology, Jilin University, Changchun, Jilin, China.,Platform for Radiation Protection and Emergency Preparedness of Southern Zhejiang, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Rui Liu
- NHC Key lab of Radiation Biology, Jilin University, Changchun, Jilin, China
| | - Yongheng Bai
- Key Laboratory of Diagnosis and Treatment of Severe Hepato-Pancreatic Diseases of Zhejiang Province, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Heya Jiang
- School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Platform for Radiation Protection and Emergency Preparedness of Southern Zhejiang, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xinxin Fu
- School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Platform for Radiation Protection and Emergency Preparedness of Southern Zhejiang, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Shumei Ma
- School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Platform for Radiation Protection and Emergency Preparedness of Southern Zhejiang, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
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15
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Ishikawa M, Williams G, Forcinito P, Ishikawa M, Petrie RJ, Saito K, Fukumoto S, Yamada Y. Pannexin 3 ER Ca 2+ channel gating is regulated by phosphorylation at the Serine 68 residue in osteoblast differentiation. Sci Rep 2019; 9:18759. [PMID: 31822768 PMCID: PMC6904572 DOI: 10.1038/s41598-019-55371-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/19/2019] [Indexed: 12/31/2022] Open
Abstract
Pannexin 3 (Panx3) is a regulator of bone formation. Panx3 forms three distinct functional channels: hemichannels, gap junctions, and endoplasmic reticulum (ER) Ca2+ channels. However, the gating mechanisms of the Panx3 channels remain unclear. Here, we show that the Panx3 ER Ca2+ channel is modulated by phosphorylation of the serine 68 residue (Ser68) to promote osteoblast differentiation. Among the 17 candidate phosphorylation sites identified, the mutation of Ser68 to Ala (Ser68Ala) was sufficient to inhibit Panx3-mediated osteoblast differentiation via reduction of Osterix and ALP expression. Using a Ser68 phospho-specific antibody (P-Panx3) revealed Panx3 was phosphorylated in prehypertrophic, hypertrophic chondrocytes, and bone areas of the newborn growth plate. In osteogenic C2C12 cells, P-Panx3 was located on the ER membranes. Importantly, the Ser68Ala mutation only affected Panx3 ER Ca2+ channel function. Ser68 on Panx3 was phosphorylated by ATP stimulation and PI3K/Akt signaling. Finally, real-time FRET imaging and ratio analysis revealed that the Panx3 channel conformation was sensitive to ATP. Together, the phosphorylation of Panx3 at Ser68 is an essential step controlling the gating of the Panx3 ER Ca2+ channel to promote osteogenesis.
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Affiliation(s)
- Masaki Ishikawa
- Operative Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8575, Japan.
| | - Geneva Williams
- Molecular Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Philadelphia, USA
| | - Patricia Forcinito
- Molecular Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Philadelphia, USA
| | - Momoko Ishikawa
- Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8576, Japan
| | - Ryan J Petrie
- Department of Biology, Drexel University, Philadelphia, PA, 19104, USA
| | - Kan Saito
- Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8576, Japan
| | - Satoshi Fukumoto
- Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8576, Japan
| | - Yoshihiko Yamada
- Molecular Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Philadelphia, USA
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16
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Li Y, Xie M, Men L, Du J. O-GlcNAcylation in immunity and inflammation: An intricate system (Review). Int J Mol Med 2019; 44:363-374. [PMID: 31198979 PMCID: PMC6605495 DOI: 10.3892/ijmm.2019.4238] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 06/06/2019] [Indexed: 12/20/2022] Open
Abstract
Chronic, low‑grade inflammation associated with obesity and diabetes result from the infiltration of adipose and vascular tissue by immune cells and contributes to cardiovascular complications. Despite an incomplete understanding of the mechanistic underpinnings of immune cell differentiation and inflammation, O‑GlcNAcylation, the addition of O‑linked N‑acetylglucosamine (O‑GlcNAc) to cytoplasmic, nuclear and mitochondrial proteins by the two cycling enzymes, the O‑linked N‑acetylglucosamine transferase (OGT) and the O‑GlcNAcase (OGA), may contribute to fine‑tune immunity and inflammation in both physiological and pathological conditions. Early studies have indicated that O‑GlcNAcylation of proteins play a pro‑inflammatory role in diabetes and insulin resistance, whereas subsequent studies have demonstrated that this post‑translational modification could also be protective against acute injuries. These studies suggest that diverse types of insults result in dynamic changes to O‑GlcNAcylation patterns, which fluctuate with cellular metabolism to promote or inhibit inflammation. In this review, the current understanding of O‑GlcNAcylation and its adaptive modulation in immune and inflammatory responses is summarized.
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Affiliation(s)
- Yu Li
- Department of Endocrinology
| | - Mingzheng Xie
- Department of General Surgery, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning 116011, P.R. China
| | | | - Jianling Du
- Department of Endocrinology
- Correspondence to: Dr Jianling Du, Department of Endocrinology, The First Affiliated Hospital of Dalian Medical University, 193 Lianhe Road, Dalian, Liaoning 116011, P.R. China, E-mail:
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17
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Inner Ear Connexin Channels: Roles in Development and Maintenance of Cochlear Function. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033233. [PMID: 30181354 DOI: 10.1101/cshperspect.a033233] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Connexin 26 and connexin 30 are the prevailing isoforms in the epithelial and connective tissue gap junction systems of the developing and mature cochlea. The most frequently encountered variants of the genes that encode these connexins, which are transcriptionally coregulated, determine complete loss of protein function and are the predominant cause of prelingual hereditary deafness. Reducing connexin 26 expression by Cre/loxP recombination in the inner ear of adult mice results in a decreased endocochlear potential, increased hearing thresholds, and loss of >90% of outer hair cells, indicating that this connexin is essential for maintenance of cochlear function. In the developing cochlea, connexins are necessary for intercellular calcium signaling activity. Ribbon synapses and basolateral membrane currents fail to mature in inner hair cells of mice that are born with reduced connexin expression, even though hair cells do not express any connexin. In contrast, pannexin 1, an alternative mediator of intercellular signaling, is dispensable for hearing acquisition and auditory function.
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18
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Cx46 hemichannel modulation by nitric oxide: Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation. Nitric Oxide 2019; 86:54-62. [DOI: 10.1016/j.niox.2019.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 02/08/2019] [Accepted: 02/20/2019] [Indexed: 01/09/2023]
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19
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Pogoda K, Kameritsch P, Mannell H, Pohl U. Connexins in the control of vasomotor function. Acta Physiol (Oxf) 2019; 225:e13108. [PMID: 29858558 DOI: 10.1111/apha.13108] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 12/13/2022]
Abstract
Vascular endothelial cells, as well as smooth muscle cells, show heterogeneity with regard to their receptor expression and reactivity. For the vascular wall to act as a functional unit, the various cells' responses require integration. Such an integration is not only required for a homogeneous response of the vascular wall, but also for the vasomotor behaviour of consecutive segments of the microvascular arteriolar tree. As flow resistances of individual sections are connected in series, sections require synchronization and coordination to allow effective changes of conductivity and blood flow. A prerequisite for the local coordination of individual vascular cells and different sections of an arteriolar tree is intercellular communication. Connexins are involved in a dual manner in this coordination. (i) By forming gap junctions between cells, they allow an intercellular exchange of signalling molecules and electrical currents. In particular, the spread of electrical currents allows for coordination of cell responses over longer distances. (ii) Connexins are able to interact with other proteins to form signalling complexes. In this way, they can modulate and integrate individual cells' responses also in a channel-independent manner. This review outlines mechanisms allowing the vascular connexins to exert their coordinating function and to regulate the vasomotor reactions of blood vessels both locally, and in vascular networks. Wherever possible, we focus on the vasomotor behaviour of small vessels and arterioles which are the main vessels determining vascular resistance, blood pressure and local blood flow.
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Affiliation(s)
- K. Pogoda
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - P. Kameritsch
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - H. Mannell
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
| | - U. Pohl
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich Germany
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20
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Khalyfa A, Gozal D. Connexins and Atrial Fibrillation in Obstructive Sleep Apnea. CURRENT SLEEP MEDICINE REPORTS 2018; 4:300-311. [PMID: 31106116 PMCID: PMC6516763 DOI: 10.1007/s40675-018-0130-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF THE REVIEW To summarize the potential interactions between obstructive sleep apnea (OSA), atrial fibrillation (AF), and connexins. RECENT FINDINGS OSA is highly prevalent in patients with cardiovascular disease, and is associated with increased risk for end-organ substantial morbidities linked to autonomic nervous system imbalance, increased oxidative stress and inflammation, ultimately leading to reduced life expectancy. Epidemiological studies indicate that OSA is associated with increased incidence and progression of coronary heart disease, heart failure, stroke, as well as arrhythmias, particularly AF. Conversely, AF is very common among subjects referred for suspected OSA, and the prevalence of AF increases with OSA severity. The interrelationships between AF and OSA along with the well-known epidemiological links between these two conditions and obesity may reflect shared pathophysiological pathways, which may depend on the intercellular diffusion of signaling molecules into either the extracellular space or require cell-to-cell contact. Connexin signaling is accomplished via direct exchanges of cytosolic molecules between adjacent cells at gap membrane junctions for cell-to-cell coupling. The role of connexins in AF is now quite well established, but the impact of OSA on cardiac connexins has only recently begun to be investigated. Understanding the biology and regulatory mechanisms of connexins in OSA at the transcriptional, translational, and post-translational levels will undoubtedly require major efforts to decipher the breadth and complexity of connexin functions in OSA-induced AF. SUMMARY The risk of end-organ morbidities has initiated the search for circulating mechanistic biomarker signatures and the implementation of biomarker-based algorithms for precision-based diagnosis and risk assessment. Here we summarize recent findings in OSA as they relate to AF risk, and also review potential mechanisms linking OSA, AF and connexins.
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Affiliation(s)
- Abdelnaby Khalyfa
- Department of Pediatrics, Biological Sciences Division, Pritzker School of Medicine, The University of Chicago, Chicago IL 60637, USA
| | - David Gozal
- Department of Child Health, University of Missouri School of Medicine, Columbia, MO 65201, USA
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21
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Shvedova M, Anfinogenova Y, Popov SV, Atochin DN. Connexins and Nitric Oxide Inside and Outside Mitochondria: Significance for Cardiac Protection and Adaptation. Front Physiol 2018; 9:479. [PMID: 29867537 PMCID: PMC5964197 DOI: 10.3389/fphys.2018.00479] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 04/16/2018] [Indexed: 12/27/2022] Open
Abstract
Irreversible myocardial damage happens in the presence of prolonged and severe ischemia. Several phenomena protect the heart against myocardial infarction and other adverse outcomes of ischemia and reperfusion (IR), namely: hibernation related to stunned myocardium, ischemic preconditioning (IPC), ischemic post-conditioning, and their pharmacological surrogates. Ischemic preconditioning consists in the induction of a brief IR to reduce damage of the tissue caused by prolonged and severe ischemia. Nitric oxide (NO) signaling plays an essential role in IPC. Nitric oxide-sensitive guanylate cyclase/cyclic guanosine-3′,5′-monophosphate (cGMP)-dependent protein kinase type I-signaling pathway protects against the IR injury during myocardial infarction. Mitochondrial ATP-sensitive and Ca2+-activated K+ channels are involved in NO-mediated signaling in IPC. Independently of the cGMP-mediated induction of NO production, S-nitrosation represents a regulatory molecular mechanism similar to phosphorylation and is essential for IPC. Unlike conditioning phenomena, the mechanistic basis of myocardial stunning and hibernation remains poorly understood. In this review article, we hypothesize that the disruption of electrical syncytium of the myocardium may underly myocardial stunning and hibernation. Considering that the connexins are the building blocks of gap junctions which represent primary structural basis of electrical syncytium, we discuss data on the involvement of connexins into myocardial conditioning, stunning, and hibernation. We also show how NO-mediated signaling is involved in myocardial stunning and hibernation. Connexins represent an essential element of adaptation phenomena of the heart at the level of both the cardio- myocytes and the mitochondria. Nitric oxide targets mitochondrial connexins which may affect electrical syncytium continuum in the heart. Mitochondrial connexins may play an essential role in NO-dependent mechanisms of myocardial adaptation to ischemia.
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Affiliation(s)
- Maria Shvedova
- Cardiovascular Research Center and Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Yana Anfinogenova
- Cardiology Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia.,RASA Center, National Research Tomsk Polytechnic University, Tomsk, Russia
| | - Sergey V Popov
- Cardiology Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia
| | - Dmitriy N Atochin
- Cardiovascular Research Center and Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States.,RASA Center, National Research Tomsk Polytechnic University, Tomsk, Russia
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22
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Guarracino JF, Cinalli AR, Veggetti MI, Losavio AS. Endogenous purines modulate K + -evoked ACh secretion at the mouse neuromuscular junction. J Neurosci Res 2018; 96:1066-1079. [PMID: 29436006 DOI: 10.1002/jnr.24223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/19/2018] [Accepted: 01/26/2018] [Indexed: 11/11/2022]
Abstract
At the mouse neuromuscular junction, adenosine triphosphate (ATP) is co-released with the neurotransmitter acetylcholine (ACh), and once in the synaptic cleft, it is hydrolyzed to adenosine. Both ATP/adenosine diphosphate (ADP) and adenosine modulate ACh secretion by activating presynaptic P2Y13 and A1 , A2A , and A3 receptors, respectively. To elucidate the action of endogenous purines on K+ -dependent ACh release, we studied the effect of purinergic receptor antagonists on miniature end-plate potential (MEPP) frequency in phrenic diaphragm preparations. At 10 mM K+ , the P2Y13 antagonist N-[2-(methylthio)ethyl]-2-[3,3,3-trifluoropropyl]thio-5'-adenylic acid, monoanhydride with (dichloromethylene)bis[phosphonic acid], tetrasodium salt (AR-C69931MX) increased asynchronous ACh secretion while the A1 , A3 , and A2A antagonists 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), (3-Ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1, 4-(±)-dihydropyridine-3,5-, dicarboxylate (MRS-1191), and 2-(2-Furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine (SCH-58261) did not modify neurosecretion. The inhibition of equilibrative adenosine transporters by S-(p-nitrobenzyl)-6-thioinosine provoked a reduction of 10 mM K+ -evoked ACh release, suggesting that the adenosine generated from ATP is being removed from the synaptic space by the transporters. At 15 and 20 mM K+ , endogenous ATP/ADP and adenosine bind to inhibitory P2Y13 and A1 and A3 receptors since AR-C69931MX, DPCPX, and MRS-1191 increased MEPP frequency. Similar results were obtained when the generation of adenosine was prevented by using the ecto-5'-nucleotidase inhibitor α,β-methyleneadenosine 5'-diphosphate sodium salt. SCH-58261 only reduced neurosecretion at 20 mM K+ , suggesting that more adenosine is needed to activate excitatory A2A receptors. At high K+ concentration, the equilibrative transporters appear to be saturated allowing the accumulation of adenosine in the synaptic cleft. In conclusion, when motor nerve terminals are depolarized by increasing K+ concentrations, the ATP/ADP and adenosine endogenously generated are able to modulate ACh secretion by sequential activation of different purinergic receptors.
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Affiliation(s)
- Juan F Guarracino
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Alejandro R Cinalli
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Mariela I Veggetti
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Adriana S Losavio
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
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23
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Ren Q, Wang ZZ, Chu SF, Xia CY, Chen NH. Gap junction channels as potential targets for the treatment of major depressive disorder. Psychopharmacology (Berl) 2018; 235:1-12. [PMID: 29178009 DOI: 10.1007/s00213-017-4782-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 11/05/2017] [Indexed: 01/08/2023]
Abstract
BACKGROUND Major depressive disorder (MDD) remains a major public health problem worldwide. The association between MDD and the dysfunction of gap junction channels (GJCs) in glial cells, especially astrocytes, is still controversial. OBJECTIVE This review provides an overview of the role of astrocyte GJCs in LMDD. RESULTS Exposure to chronic unpredictable stress caused a reduction in connexin expression in the rat prefrontal cortex, a result that is consistent with clinical findings reported in postmortem studies of brains from MDD patients. Chronic antidepressant treatment in these rats increased the expression of connexins. However, pharmacological GJC blockade in normal rodents decreased connexin expression and caused depressive-like behaviors. Furthermore, GJC dysfunction affects electrical conductance, metabolic coupling and secondary messengers, and inflammatory responses, which are consistent with current hypotheses on MDD. All these results provide a comprehensive overview of the neurobiology of MDD. CONCLUSION This review supports the hypothesis that the regulation of GJCs between astrocytes could be an underlying mechanism for the therapeutic effect of antidepressants.
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Affiliation(s)
- Qian Ren
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Shi-Feng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China. .,College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.
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24
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Zhang X, Zhao F, Zhao JF, Fu HY, Huang XJ, Lv BD. PDGF-mediated PI3K/AKT/β-catenin signaling regulates gap junctions in corpus cavernosum smooth muscle cells. Exp Cell Res 2017; 362:252-259. [PMID: 29174980 DOI: 10.1016/j.yexcr.2017.11.025] [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: 09/04/2017] [Revised: 11/17/2017] [Accepted: 11/18/2017] [Indexed: 02/06/2023]
Abstract
Erectile dysfunction (ED) is the most common sexual disorder that men report to healthcare providers. Gap junctions (GJs) are thought to be responsible for synchronous shrinkage of corpus cavernosum smooth muscle cells (CCSMCs), and play thus an important role in the maintenance of an erection. Hypoxia has been suggested as a pathological mechanism underlying ED. Here we demonstrate that hypoxia increased the expression of platelet-derived growth factor (PDGF) and the main GJ component connexin (Cx)43 in CCSMCs. Inhibiting PDGF receptor (PDGFR) activity decreased Cx43 expression. Treatment with different concentrations of PDGF increased the levels of phosphorylated protein kinase B (AKT), β-catenin, and Cx43, whereas inhibition of PDGFR or activation of phosphatidylinositol 3 kinase (PI3K)/AKT signaling altered β-catenin and Cx43 expression. Meanwhile, silencing β-catenin resulted in the downregulation of Cx43. These results demonstrate that PDGF secretion by CCSMCs and vascular endothelial cells is enhanced under hypoxic conditions, leading to increased Cx43 expression through PI3K/AKT/β-catenin signaling and ultimately affecting GJ function in ED. Thus, targeting this pathway is a potential therapeutic strategy for the treatment of ED.
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Affiliation(s)
- Xiang Zhang
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Fan Zhao
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jian-Feng Zhao
- Department of Urology, The Second Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Hui-Ying Fu
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China; Andrology Laboratory on Integration of Chinese and Western Medicine, Zhejiang Provincial Key Laboratory of Traditional Chinese Medicine, Hangzhou, China
| | - Xiao-Jun Huang
- Department of Urology, The Second Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Bo-Dong Lv
- Department of Urology, The Second Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China; Andrology Laboratory on Integration of Chinese and Western Medicine, Zhejiang Provincial Key Laboratory of Traditional Chinese Medicine, Hangzhou, China.
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25
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Ribeiro-Rodrigues TM, Martins-Marques T, Morel S, Kwak BR, Girão H. Role of connexin 43 in different forms of intercellular communication - gap junctions, extracellular vesicles and tunnelling nanotubes. J Cell Sci 2017; 130:3619-3630. [PMID: 29025971 DOI: 10.1242/jcs.200667] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Communication is important to ensure the correct and efficient flow of information, which is required to sustain active social networks. A fine-tuned communication between cells is vital to maintain the homeostasis and function of multicellular or unicellular organisms in a community environment. Although there are different levels of complexity, intercellular communication, in prokaryotes to mammalians, can occur through secreted molecules (either soluble or encapsulated in vesicles), tubular structures connecting close cells or intercellular channels that link the cytoplasm of adjacent cells. In mammals, these different types of communication serve different purposes, may involve distinct factors and are mediated by extracellular vesicles, tunnelling nanotubes or gap junctions. Recent studies have shown that connexin 43 (Cx43, also known as GJA1), a transmembrane protein initially described as a gap junction protein, participates in all these forms of communication; this emphasizes the concept of adopting strategies to maximize the potential of available resources by reutilizing the same factor in different scenarios. In this Review, we provide an overview of the most recent advances regarding the role of Cx43 in intercellular communication mediated by extracellular vesicles, tunnelling nanotubes and gap junctions.
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Affiliation(s)
- Teresa M Ribeiro-Rodrigues
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Tânia Martins-Marques
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Sandrine Morel
- Dept. of Pathology and Immunology, and Dept. of Medical Specialties - Cardiology, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Brenda R Kwak
- Dept. of Pathology and Immunology, and Dept. of Medical Specialties - Cardiology, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Henrique Girão
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-548 Coimbra, Portugal .,CNC.IBILI, University of Coimbra, 3000-548 Coimbra, Portugal
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26
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Escalona Y, Garate JA, Araya-Secchi R, Huynh T, Zhou R, Perez-Acle T. Exploring the Membrane Potential of Simple Dual-Membrane Systems as Models for Gap-Junction Channels. Biophys J 2017; 110:2678-2688. [PMID: 27332126 DOI: 10.1016/j.bpj.2016.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 11/26/2022] Open
Abstract
The conductance of ion channels can be modulated by a transmembrane potential difference, due to alterations on ion-mobility and also by changes in the pore structure. Despite the vast knowledge regarding the influence of voltage on transport properties of ion channels, little attention has been paid to describe, with atomic detail, the modulation of ionic transport in gap-junction channels (GJCs). Hence, molecular dynamics simulations were performed to explore the conductance of simple dual-membrane systems that account for the very basic features of GJCs. In doing so, we studied the influence of different charge distributions in the channel surface on these idealized systems under external electric fields, paying attention to the behavior of the electrostatic potential, ion density, ion currents, and equilibrium properties. Our results demonstrate that the incorporation of a charge distribution akin GJCs decreased anionic currents, favoring the transport of cationic species. Moreover, a thermodynamic characterization of ionic transport in these systems demonstrate the existence of a kinetic barrier that hinders anionic currents, reinforcing the role played by the internal arrangement of charges in GJCs. Overall, our results provide insights at the atomic scale on the effects of charge distributions over ionic transport, constituting a step forward into a better understanding of GJCs.
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Affiliation(s)
- Yerko Escalona
- Computational Biology Lab (DLab), Fundación Ciencia & Vida, Santiago, Chile
| | - Jose A Garate
- Computational Biology Lab (DLab), Fundación Ciencia & Vida, Santiago, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Raul Araya-Secchi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Tien Huynh
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, New York
| | - Ruhong Zhou
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, New York
| | - Tomas Perez-Acle
- Computational Biology Lab (DLab), Fundación Ciencia & Vida, Santiago, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile.
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27
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Boyce AKJ, Epp AL, Nagarajan A, Swayne LA. Transcriptional and post-translational regulation of pannexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:72-82. [PMID: 28279657 DOI: 10.1016/j.bbamem.2017.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 12/21/2022]
Abstract
Pannexins are a 3-membered family of proteins that form large pore ion and metabolite channels in vertebrates. The impact of pannexins on vertebrate biology is intricately tied to where and when they are expressed, and how they are modified, once produced. The purpose of this review is therefore to outline our current understanding of transcriptional and post-translational regulation of pannexins. First, we briefly summarize their discovery and characteristics. Next, we describe several aspects of transcriptional regulation, including cell and tissue-specific expression, dynamic expression over development and disease, as well as new insights into the underlying molecular machinery involved. Following this, we delve into the role of post-translational modifications in the regulation of trafficking and channel properties, highlighting important work on glycosylation, phosphorylation, S-nitrosylation and proteolytic cleavage. Embedded throughout, we also highlight important knowledge gaps and avenues of future research. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Andrew K J Boyce
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada
| | - Anna L Epp
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada
| | - Archana Nagarajan
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada
| | - Leigh Anne Swayne
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver V6T 1Z3, Canada.
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28
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Vargas AA, Cisterna BA, Saavedra-Leiva F, Urrutia C, Cea LA, Vielma AH, Gutierrez-Maldonado SE, Martin AJM, Pareja-Barrueto C, Escalona Y, Schmachtenberg O, Lagos CF, Perez-Acle T, Sáez JC. On Biophysical Properties and Sensitivity to Gap Junction Blockers of Connexin 39 Hemichannels Expressed in HeLa Cells. Front Physiol 2017; 8:38. [PMID: 28232803 PMCID: PMC5298994 DOI: 10.3389/fphys.2017.00038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/13/2017] [Indexed: 02/02/2023] Open
Abstract
Although connexins (Cxs) are broadly expressed by cells of mammalian organisms, Cx39 has a very restricted pattern of expression and the biophysical properties of Cx39-based channels [hemichannels (HCs) and gap junction channels (GJCs)] remain largely unknown. Here, we used HeLa cells transfected with Cx39 (HeLa-Cx39 cells) in which intercellular electrical coupling was not detected, indicating the absence of GJCs. However, functional HCs were found on the surface of cells exposed to conditions known to increase the open probability of other Cx HCs (e.g., extracellular divalent cationic-free solution (DCFS), extracellular alkaline pH, mechanical stimulus and depolarization to positive membrane potentials). Cx39 HCs were blocked by some traditional Cx HC blockers, but not by others or a pannexin1 channel blocker. HeLa-Cx39 cells showed similar resting membrane potentials (RMPs) to those of parental cells, and exposure to DCFS reduced RMPs in Cx39 transfectants, but not in parental cells. Under these conditions, unitary events of ~75 pS were frequent in HeLa-Cx39 cells and absent in parental cells. Real-time cellular uptake experiments of dyes with different physicochemical features, as well as the application of a machine-learning approach revealed that Cx39 HCs are preferentially permeable to molecules characterized by six categories of descriptors, namely: (1) electronegativity, (2) ionization potential, (3) polarizability, (4) size and geometry, (5) topological flexibility and (6) valence. However, Cx39 HCs opened by mechanical stimulation or alkaline pH were impermeable to Ca2+. Molecular modeling of Cx39-based channels suggest that a constriction present at the intracellular portion of the para helix region co-localizes with an electronegative patch, imposing an energetic and steric barrier, which in the case of GJCs may hinder channel function. Results reported here demonstrate that Cx39 form HCs and add to our understanding of the functional roles of Cx39 HCs under physiological and pathological conditions in cells that express them.
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Affiliation(s)
- Anibal A Vargas
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Bruno A Cisterna
- Departamento de Fisiología, Pontificia Universidad Católica de ChileSantiago, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaíso, Chile
| | - Fujiko Saavedra-Leiva
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Carolina Urrutia
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Luis A Cea
- Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile Santiago, Chile
| | - Alex H Vielma
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Sebastian E Gutierrez-Maldonado
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaíso, Chile; Computational Biology Lab (DLab), Fundación Ciencia & VidaSantiago, Chile
| | - Alberto J M Martin
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaíso, Chile; Computational Biology Lab (DLab), Fundación Ciencia & VidaSantiago, Chile
| | | | - Yerko Escalona
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaíso, Chile; Computational Biology Lab (DLab), Fundación Ciencia & VidaSantiago, Chile
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Carlos F Lagos
- Department of Endocrinology, School of Medicine, Pontificia Universidad Católica de ChileSantiago, Chile; Facultad de Ciencia, Universidad San SebastiánSantiago, Chile
| | - Tomas Perez-Acle
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaíso, Chile; Computational Biology Lab (DLab), Fundación Ciencia & VidaSantiago, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de ChileSantiago, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaíso, Chile
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29
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Puebla C, Retamal MA, Acuña R, Sáez JC. Regulation of Connexin-Based Channels by Fatty Acids. Front Physiol 2017; 8:11. [PMID: 28174541 PMCID: PMC5258758 DOI: 10.3389/fphys.2017.00011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 01/06/2017] [Indexed: 01/29/2023] Open
Abstract
In this mini-review, we briefly summarize the current knowledge about the effects of fatty acids (FAs) on connexin-based channels, as well as discuss the limited information about the impact FAs may have on pannexins (Panxs). FAs regulate diverse cellular functions, some of which are explained by changes in the activity of channels constituted by connexins (Cxs) or Panxs, which are known to play critical roles in maintaining the functional integrity of diverse organs and tissues. Cxs are transmembrane proteins that oligomerize into hexamers to form hemichannels (HCs), which in turn can assemble into dodecamers to form gap junction channels (GJCs). While GJCs communicate the cytoplasm of contacting cells, HCs serve as pathways for the exchange of ions and small molecules between the intra and extracellular milieu. Panxs, as well as Cx HCs, form channels at the plasma membrane that enable the interchange of molecules between the intra and extracellular spaces. Both Cx- and Panx-based channels are controlled by several post-translational modifications. However, the mechanism of action of FAs on these channels has not been described in detail. It has been shown however that FAs frequently decrease GJC-mediated cell-cell communication. The opposite effect also has been described for HC or Panx-dependent intercellular communication, where, the acute FA effect can be reversed upon washout. Additionally, changes in GJCs mediated by FAs have been associated with post-translational modifications (e.g., phosphorylation), and seem to be directly related to chemical properties of FAs (e.g., length of carbon chain and/or degree of saturation), but this possible link remains poorly understood.
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Affiliation(s)
- Carlos Puebla
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de ChileSantiago, Chile; Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del DesarrolloSantiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo Santiago, Chile
| | - Rodrigo Acuña
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo Santiago, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de ChileSantiago, Chile; Centro Interdisciplinario de Neurociencias de Valparaíso, Intituto Milenio, Universidad de ValparaísoValparaíso, Chile
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30
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Begandt D, Good ME, Keller AS, DeLalio LJ, Rowley C, Isakson BE, Figueroa XF. Pannexin channel and connexin hemichannel expression in vascular function and inflammation. BMC Cell Biol 2017; 18:2. [PMID: 28124621 PMCID: PMC5267334 DOI: 10.1186/s12860-016-0119-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Control of blood flow distribution and tissue homeostasis depend on the tight regulation of and coordination between the microvascular network and circulating blood cells. Channels formed by connexins or pannexins that connect the intra- and extracellular compartments allow the release of paracrine signals, such as ATP and prostaglandins, and thus play a central role in achieving fine regulation and coordination of vascular function. This review focuses on vascular connexin hemichannels and pannexin channels. We review their expression pattern within the arterial and venous system with a special emphasis on how post-translational modifications by phosphorylation and S-nitrosylation of these channels modulate their function and contribute to vascular homeostasis. Furthermore, we highlight the contribution of these channels in smooth muscle cells and endothelial cells in the regulation of vasomotor tone as well as how these channels in endothelial cells regulate inflammatory responses such as during ischemic and hypoxic conditions. In addition, this review will touch on recent evidence implicating a role for these proteins in regulating red blood cell and platelet function.
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Affiliation(s)
- Daniela Begandt
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Miranda E Good
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Alex S Keller
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Leon J DeLalio
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Carol Rowley
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Brant E Isakson
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Xavier F Figueroa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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31
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Willebrords J, Crespo Yanguas S, Maes M, Decrock E, Wang N, Leybaert L, da Silva TC, Veloso Alves Pereira I, Jaeschke H, Cogliati B, Vinken M. Structure, Regulation and Function of Gap Junctions in Liver. ACTA ACUST UNITED AC 2016; 22:29-37. [PMID: 27001459 DOI: 10.3109/15419061.2016.1151875] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gap junctions are a specialized group of cell-to-cell junctions that mediate direct intercellular communication between cells. They arise from the interaction of two hemichannels of adjacent cells, which in turn are composed of six connexin proteins. In liver, gap junctions are predominantly found in hepatocytes and play critical roles in virtually all phases of the hepatic life cycle, including cell growth, differentiation, liver-specific functionality and cell death. Liver gap junctions are directed through a broad variety of mechanisms ranging from epigenetic control of connexin expression to post-translational regulation of gap junction activity. This paper reviews established and novel aspects regarding the architecture, control and functional relevance of liver gap junctions.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - Tereza Cristina da Silva
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Isabel Veloso Alves Pereira
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Hartmut Jaeschke
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
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Nutrient Starvation Decreases Cx43 Levels and Limits Intercellular Communication in Primary Bovine Corneal Endothelial Cells. J Membr Biol 2016; 249:363-73. [PMID: 26873723 DOI: 10.1007/s00232-016-9874-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/22/2016] [Indexed: 12/11/2022]
Abstract
Connexin (Cx) proteins form large conductance channels which function as regulators of communication between neighboring cells via gap junctions and/or hemichannels. Intercellular communication is essential to coordinate cellular responses in tissues and organs, thereby fulfilling an essential role in the spreading of signaling, survival and death processes. Connexin 43 (Cx43), a major connexin isoform in brain and heart, is rapidly turned over. Recent studies implicated that autophagy, a lysosomal degradation pathway induced upon nutrient starvation, mediates connexins, including Cx43, degradation. Here, we examined the impact of nutrient starvation on endogenous Cx43-protein levels and endogenous Cx43-driven intercellular communication in primary bovine corneal endothelial cells (BCECs). Hank's Balanced Salt Solution (HBSS) was used as a starvation condition that induces autophagic flux without impacting the survival of the BCECs. Nutrient starvation of BCECs caused a rapid decline in Cx43-protein levels, both as gap junctions and as hemichannels. The time course of the decline in Cx43-protein levels coincided with the time course of the decline in intercellular communication, assessed as intercellular Ca(2+)-wave propagation in BCECs exposed to a single-cell mechanical stimulus. The decline in Cx43-protein levels, both as gap junctions and as hemichannels, could be prevented by the addition of bafilomycin A1, a lysosomal inhibitor, during the complete nutrient starvation period. Consistent with this, bafilomycin A1 significantly alleviated the decrease in intercellular Ca(2+)-wave propagation. This study further underpins the importance of autophagy as an important degradation pathway for Cx43 proteins during periods of nutrient deprivation, thereby impacting the ability of cells to perform intercellular communication.
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Maes M, Willebrords J, Crespo Yanguas S, Cogliati B, Vinken M. Analysis of Liver Connexin Expression Using Reverse Transcription Quantitative Real-Time Polymerase Chain Reaction. Methods Mol Biol 2016; 1437:1-19. [PMID: 27207283 DOI: 10.1007/978-1-4939-3664-9_1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although connexin production is mainly regulated at the protein level, altered connexin gene expression has been identified as the underlying mechanism of several pathologies. When studying the latter, appropriate methods to quantify connexin RNA levels are required. The present chapter describes a well-established reverse transcription quantitative real-time polymerase chain reaction procedure optimized for analysis of hepatic connexins. The method includes RNA extraction and subsequent quantification, generation of complementary DNA, quantitative real-time polymerase chain reaction, and data analysis.
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Affiliation(s)
- Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarkbeeklaan 103, 1090, Jette, Brussel, Belgium.
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarkbeeklaan 103, 1090, Jette, Brussel, Belgium
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarkbeeklaan 103, 1090, Jette, Brussel, Belgium
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, SP, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Laarkbeeklaan 103, 1090, Jette, Brussel, Belgium
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34
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Lohman AW, Straub AC, Johnstone SR. Identification of Connexin43 Phosphorylation and S-Nitrosylation in Cultured Primary Vascular Cells. Methods Mol Biol 2016; 1437:97-111. [PMID: 27207289 DOI: 10.1007/978-1-4939-3664-9_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
All connexins (Cx) proteins contain both highly ordered domains (i.e., 4 transmembrane domains) and primarily unstructured regions (i.e., n- and c-terminal domains). The c-terminal domains vary in length and amino acid composition from the shortest on Cx26 to the longest on Cx43. With the exception of Cx26, the c-terminal domains contain multiple sites for posttranslational modification (PTM) including serines (S), threonines (T), and tyrosines (Y) for phosphorylation or cysteines (C) for S-nitrosylation. These PTMs are critical for regulating cellular localization, protein-protein interactions, and channel functionality. There are several biochemical techniques that allow for the identification of these PTM including Western blotting and the "Biotin Switch" assay for nitrosylation. Quantitative analysis of Western blots can be achieved through use of secondary antibodies in the near infrared scale and high-resolution scanning on a fluorescent scanner.
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Affiliation(s)
- Alexander W Lohman
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, T2N 4N1
| | - Adam C Straub
- Department of Pharmacology and Chemical Biology, Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Scott R Johnstone
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow, G12 8TA, UK.
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Metabolic Serum Profiles for Patients Receiving Allogeneic Stem Cell Transplantation: The Pretransplant Profile Differs for Patients with and without Posttransplant Capillary Leak Syndrome. DISEASE MARKERS 2015; 2015:943430. [PMID: 26609191 PMCID: PMC4644835 DOI: 10.1155/2015/943430] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/01/2015] [Indexed: 12/25/2022]
Abstract
Allogeneic stem cell transplantation is commonly used in the treatment of younger patients with severe hematological diseases, and endothelial cells seem to be important for the development of several posttransplant complications. Capillary leak syndrome is a common early posttransplant complication where endothelial cell dysfunction probably contributes to the pathogenesis. In the present study we investigated whether the pretreatment serum metabolic profile reflects a risk of posttransplant capillary leak syndrome. We investigated the pretransplant serum levels of 766 metabolites for 80 consecutive allotransplant recipients. Patients with later capillary leak syndrome showed increased pretherapy levels of metabolites associated with endothelial dysfunction (homocitrulline, adenosine) altered renal regulation of fluid and/or electrolyte balance (betaine, methoxytyramine, and taurine) and altered vascular function (cytidine, adenosine, and methoxytyramine). Additional bioinformatical analyses showed that capillary leak syndrome was also associated with altered purine/pyrimidine metabolism (i.e., metabolites involved in vascular regulation and endothelial functions), aminoglycosylation (possibly important for endothelial cell functions), and eicosanoid metabolism (also involved in vascular regulation). Our observations are consistent with the hypothesis that the pretransplant metabolic status can be a marker for posttransplant abnormal fluid and/or electrolyte balance.
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Jiang G, Li L, Wu X, Dong S, Tong X. [Influence of Berberine on Cisplatin Antineoplastic Effect in A549 Cells]. ZHONGGUO FEI AI ZA ZHI = CHINESE JOURNAL OF LUNG CANCER 2015; 18:481-6. [PMID: 26302344 PMCID: PMC6000235 DOI: 10.3779/j.issn.1009-3419.2015.08.03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
背景与目的 以顺铂为基础的化疗方案是晚期非小细胞肺癌的一线化疗方案,但是由于顺铂的不良反应严重及耐药性的产生均限制了它的临床应用,本研究采用联合用药的方式观察黄连素对顺铂抗肿瘤作用的影响,并探讨其可能机制。 方法 分别观察黄连素对肺腺癌细胞A549细胞中总Cx43蛋白、细胞膜Cx43蛋白的表达以及细胞缝隙连接功能的改变,通过标准细胞集落克隆实验观察黄连素对顺铂细胞毒性的影响;并观察PKC激酶的表达。 结果 黄连素在0 μM-10 μM浓度范围内对细胞无毒性,通过增加细胞内总Cx43蛋白和胞膜Cx43蛋白的表达而增强细胞缝隙连接功能;这种作用与PKC的活性被抑制相关,抑制PKC活性可以进一步增加顺铂对A549细胞的毒性作用。 结论 黄连素可通过增加A549细胞的缝隙连接功能而明显增强顺铂的细胞毒性。
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Affiliation(s)
- Guojun Jiang
- Faculty of Pharmacy, Bengbu Medical College/Anhui Engineering Technology Research Center of Biochemical Pharmaceuticals, Bengbu 233030, China
| | - Li Li
- Faculty of Pharmacy, Bengbu Medical College/Anhui Engineering Technology Research Center of Biochemical Pharmaceuticals, Bengbu 233030, China
| | - Xiaoxiang Wu
- Faculty of Pharmacy, Bengbu Medical College/Anhui Engineering Technology Research Center of Biochemical Pharmaceuticals, Bengbu 233030, China
| | - Shuying Dong
- Faculty of Pharmacy, Bengbu Medical College/Anhui Engineering Technology Research Center of Biochemical Pharmaceuticals, Bengbu 233030, China
| | - Xuhui Tong
- Faculty of Pharmacy, Bengbu Medical College/Anhui Engineering Technology Research Center of Biochemical Pharmaceuticals, Bengbu 233030, China
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Introduction: connexins, pannexins and their channels as gatekeepers of organ physiology. Cell Mol Life Sci 2015; 72:2775-8. [PMID: 26084871 DOI: 10.1007/s00018-015-1958-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 06/11/2015] [Indexed: 12/13/2022]
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Connexin 43 ubiquitination determines the fate of gap junctions: restrict to survive. Biochem Soc Trans 2015; 43:471-5. [DOI: 10.1042/bst20150036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Connexins (Cxs) are transmembrane proteins that form channels which allow direct intercellular communication (IC) between neighbouring cells via gap junctions. Mechanisms that modulate the amount of channels at the plasma membrane have emerged as important regulators of IC and their de-regulation has been associated with various diseases. Although Cx-mediated IC can be modulated by different mechanisms, ubiquitination has been described as one of the major post-translational modifications involved in Cx regulation and consequently IC. In this review, we focus on the role of ubiquitin and its effect on gap junction intercellular communication.
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Retamal MA, León-Paravic CG, Ezquer M, Ezquer F, Rio RD, Pupo A, Martínez AD, González C. Carbon monoxide: A new player in the redox regulation of connexin hemichannels. IUBMB Life 2015; 67:428-37. [DOI: 10.1002/iub.1388] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/05/2015] [Indexed: 01/23/2023]
Affiliation(s)
- Mauricio A. Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Carmen G. León-Paravic
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Marcelo Ezquer
- Centro de Medicina Regenerativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Fernando Ezquer
- Centro de Medicina Regenerativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Rodrigo Del Rio
- Centro de Investigación Biomédica; Universidad Autónoma de Chile; Santiago Chile
| | - Amaury Pupo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias; Instituto de Neurociencia; Universidad de Valparaíso; Valparaíso Chile
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias; Instituto de Neurociencia; Universidad de Valparaíso; Valparaíso Chile
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias; Instituto de Neurociencia; Universidad de Valparaíso; Valparaíso Chile
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Zhang SS, Shaw RM. Trafficking highways to the intercalated disc: new insights unlocking the specificity of connexin 43 localization. ACTA ACUST UNITED AC 2014; 21:43-54. [PMID: 24460200 DOI: 10.3109/15419061.2013.876014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
With each heartbeat, billions of cardiomyocytes work in concert to propagate the electrical excitation needed to effectively circulate blood. Regulated expression and timely delivery of connexin proteins to form gap junctions at the specialized cell-cell contact region, known as the intercalated disc, is essential to ventricular cardiomyocyte coupling. We focus this review on several regulatory mechanisms that have been recently found to govern the lifecycle of connexin 43 (Cx43), the short-lived and most abundantly expressed connexin in cardiac ventricular muscle. The Cx43 lifecycle begins with gene expression, followed by oligomerization into hexameric channels, and then cytoskeletal-based transport toward the disc region. Once delivered, hemichannels interact with resident disc proteins and are organized to effect intercellular coupling. We highlight recent studies exploring regulation of Cx43 localization to the intercalated disc, with emphasis on alternatively translated Cx43 isoforms and cytoskeletal transport machinery that together regulate Cx43 gap junction coupling between cardiomyocytes.
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Kurtenbach S, Kurtenbach S, Zoidl G. Emerging functions of pannexin 1 in the eye. Front Cell Neurosci 2014; 8:263. [PMID: 25309318 PMCID: PMC4163987 DOI: 10.3389/fncel.2014.00263] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/14/2014] [Indexed: 01/23/2023] Open
Abstract
Pannexin 1 (Panx1) is a high-conductance, voltage-gated channel protein found in vertebrates. Panx1 is widely expressed in many organs and tissues, including sensory systems. In the eye, Panx1 is expressed in major divisions including the retina, lens and cornea. Panx1 is found in different neuronal and non-neuronal cell types. The channel is mechanosensitive and responds to changes in extracellular ATP, intracellular calcium, pH, or ROS/nitric oxide. Since Panx1 channels operate at the crossroad of major signaling pathways, physiological functions in important autocrine and paracrine feedback signaling mechanisms were hypothesized. This review starts with describing in depth the initial Panx1 expression and localization studies fostering functional studies that uncovered distinct roles in processing visual information in subsets of neurons in the rodent and fish retina. Panx1 is expressed along the entire anatomical axis from optical nerve to retina and cornea in glia, epithelial and endothelial cells as well as in neurons. The expression and diverse localizations throughout the eye points towards versatile functions of Panx1 in neuronal and non-neuronal cells, implicating Panx1 in the crosstalk between immune and neural cells, pressure related pathological conditions like glaucoma, wound repair or neuronal cell death caused by ischemia. Summarizing the literature on Panx1 in the eye highlights the diversity of emerging Panx1 channel functions in health and disease.
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Affiliation(s)
- Sarah Kurtenbach
- Department of Psychology, Faculty of Health, York University Toronto, ON, Canada
| | - Stefan Kurtenbach
- Department of Psychology, Faculty of Health, York University Toronto, ON, Canada
| | - Georg Zoidl
- Department of Psychology, Faculty of Health, York University Toronto, ON, Canada ; Department of Biology, Faculty of Science, York University Toronto, ON, Canada
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Sáez PJ, Shoji KF, Aguirre A, Sáez JC. Regulation of hemichannels and gap junction channels by cytokines in antigen-presenting cells. Mediators Inflamm 2014; 2014:742734. [PMID: 25301274 PMCID: PMC4180397 DOI: 10.1155/2014/742734] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 06/19/2014] [Indexed: 12/13/2022] Open
Abstract
Autocrine and paracrine signals coordinate responses of several cell types of the immune system that provide efficient protection against different challenges. Antigen-presenting cells (APCs) coordinate activation of this system via homocellular and heterocellular interactions. Cytokines constitute chemical intercellular signals among immune cells and might promote pro- or anti-inflammatory effects. During the last two decades, two membrane pathways for intercellular communication have been demonstrated in cells of the immune system. They are called hemichannels (HCs) and gap junction channels (GJCs) and provide new insights into the mechanisms of the orchestrated response of immune cells. GJCs and HCs are permeable to ions and small molecules, including signaling molecules. The direct intercellular transfer between contacting cells can be mediated by GJCs, whereas the release to or uptake from the extracellular milieu can be mediated by HCs. GJCs and HCs can be constituted by two protein families: connexins (Cxs) or pannexins (Panxs), which are present in almost all APCs, being Cx43 and Panx1 the most ubiquitous members of each protein family. In this review, we focus on the effects of different cytokines on the intercellular communication mediated by HCs and GJCs in APCs and their impact on purinergic signaling.
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Affiliation(s)
- Pablo J. Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda 340, 6513677 Santiago, Chile
| | - Kenji F. Shoji
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda 340, 6513677 Santiago, Chile
| | - Adam Aguirre
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda 340, 6513677 Santiago, Chile
| | - Juan C. Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda 340, 6513677 Santiago, Chile
- Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Pasaje Harrington 287, Playa Ancha, 2360103 Valparaíso, Chile
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Newman RH, Zhang J, Zhu H. Toward a systems-level view of dynamic phosphorylation networks. Front Genet 2014; 5:263. [PMID: 25177341 PMCID: PMC4133750 DOI: 10.3389/fgene.2014.00263] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/16/2014] [Indexed: 11/13/2022] Open
Abstract
To better understand how cells sense and respond to their environment, it is important to understand the organization and regulation of the phosphorylation networks that underlie most cellular signal transduction pathways. These networks, which are composed of protein kinases, protein phosphatases and their respective cellular targets, are highly dynamic. Importantly, to achieve signaling specificity, phosphorylation networks must be regulated at several levels, including at the level of protein expression, substrate recognition, and spatiotemporal modulation of enzymatic activity. Here, we briefly summarize some of the traditional methods used to study the phosphorylation status of cellular proteins before focusing our attention on several recent technological advances, such as protein microarrays, quantitative mass spectrometry, and genetically-targetable fluorescent biosensors, that are offering new insights into the organization and regulation of cellular phosphorylation networks. Together, these approaches promise to lead to a systems-level view of dynamic phosphorylation networks.
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Affiliation(s)
- Robert H Newman
- Department of Biology, North Carolina Agricultural and Technical State University Greensboro, NC, USA
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine Baltimore, MD, USA ; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine Baltimore, MD, USA ; Department of Oncology, Johns Hopkins University School of Medicine Baltimore, MD, USA ; Department of Chemical and Biomolecular Engineering, Johns Hopkins University School of Medicine Baltimore, MD, USA
| | - Heng Zhu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine Baltimore, MD, USA ; High-Throughput Biology Center, Institute for Basic Biomedical Sciences, Johns Hopkins University Baltimore, MD, USA
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44
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Molica F, Meens MJP, Morel S, Kwak BR. Mutations in cardiovascular connexin genes. Biol Cell 2014; 106:269-93. [PMID: 24966059 DOI: 10.1111/boc.201400038] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 06/20/2014] [Indexed: 12/25/2022]
Abstract
Connexins (Cxs) form a family of transmembrane proteins comprising 21 members in humans. Cxs differ in their expression patterns, biophysical properties and ability to combine into homomeric or heteromeric gap junction channels between neighbouring cells. The permeation of ions and small metabolites through gap junction channels or hemichannels confers a crucial role to these proteins in intercellular communication and in maintaining tissue homeostasis. Among others, Cx37, Cx40, Cx43, Cx45 and Cx47 are found in heart, blood and lymphatic vessels. Mutations or polymorphisms in the genes coding for these Cxs have not only been implicated in cardiovascular pathologies but also in a variety of other disorders. While mutations in Cx43 are mostly linked to oculodentodigital dysplasia, Cx47 mutations are associated with Pelizaeus-Merzbacher-like disease and lymphoedema. Cx40 mutations are principally linked to atrial fibrillation. Mutations in Cx37 have not yet been described, but polymorphisms in the Cx37 gene have been implicated in the development of arterial disease. This review addresses current knowledge on gene mutations in cardiovascular Cxs systematically and links them to alterations in channel properties and disease.
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Affiliation(s)
- Filippo Molica
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland; Department of Medical Specializations - Cardiology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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45
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Gonzalez DR, Treuer AV, Lamirault G, Mayo V, Cao Y, Dulce RA, Hare JM. NADPH oxidase-2 inhibition restores contractility and intracellular calcium handling and reduces arrhythmogenicity in dystrophic cardiomyopathy. Am J Physiol Heart Circ Physiol 2014; 307:H710-21. [PMID: 25015966 DOI: 10.1152/ajpheart.00890.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Duchenne muscular dystrophy may affect cardiac muscle, producing a dystrophic cardiomyopathy in humans and the mdx mouse. We tested the hypothesis that oxidative stress participates in disrupting calcium handling and contractility in the mdx mouse with established cardiomyopathy. We found increased expression (fivefold) of the NADPH oxidase (NOX) 2 in the mdx hearts compared with wild type, along with increased superoxide production. Next, we tested the impact of NOX2 inhibition on contractility and calcium handling in isolated cardiomyocytes. Contractility was decreased in mdx myocytes compared with wild type, and this was restored toward normal by pretreating with apocynin. In addition, the amplitude of evoked intracellular Ca(2+) concentration transients that was diminished in mdx myocytes was also restored with NOX2 inhibition. Total sarcoplasmic reticulum (SR) Ca(2+) content was reduced in mdx hearts and normalized by apocynin treatment. Additionally, NOX2 inhibition decreased the production of spontaneous diastolic calcium release events and decreased the SR calcium leak in mdx myocytes. In addition, nitric oxide (NO) synthase 1 (NOS-1) expression was increased eightfold in mdx hearts compared with wild type. Nevertheless, cardiac NO production was reduced. To test whether this paradox implied NOS-1 uncoupling, we treated cardiac myocytes with exogenous tetrahydrobioterin, along with the NOX inhibitor VAS2870. These agents restored NO production and phospholamban phosphorylation in mdx toward normal. Together, these results demonstrate that, in mdx hearts, NOX2 inhibition improves the SR calcium handling and contractility, partially by recoupling NOS-1. These findings reveal a new layer of nitroso-redox imbalance in dystrophic cardiomyopathy.
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Affiliation(s)
- Daniel R Gonzalez
- Departamento de Ciencias Basicas Biomedicas, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile; and
| | - Adriana V Treuer
- Departamento de Ciencias Basicas Biomedicas, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile; and
| | - Guillaume Lamirault
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, Florida
| | - Vera Mayo
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, Florida
| | - Yenong Cao
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, Florida
| | - Raul A Dulce
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, Florida
| | - Joshua M Hare
- Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, Florida
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46
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Schalper KA, Carvajal-Hausdorf D, Oyarzo MP. Possible role of hemichannels in cancer. Front Physiol 2014; 5:237. [PMID: 25018732 PMCID: PMC4073485 DOI: 10.3389/fphys.2014.00237] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022] Open
Abstract
In humans, connexins (Cxs) and pannexins (Panxs) are the building blocks of hemichannels. These proteins are frequently altered in neoplastic cells and have traditionally been considered as tumor suppressors. Alteration of Cxs and Panxs in cancer cells can be due to genetic, epigenetic and post-transcriptional/post-translational events. Activated hemichannels mediate the diffusional membrane transport of ions and small signaling molecules. In the last decade hemichannels have been shown to participate in diverse cell processes including the modulation of cell proliferation and survival. However, their possible role in tumor growth and expansion remains largely unexplored. Herein, we hypothesize about the possible role of hemichannels in carcinogenesis and tumor progression. To support this theory, we summarize the evidence regarding the involvement of hemichannels in cell proliferation and migration, as well as their possible role in the anti-tumor immune responses. In addition, we discuss the evidence linking hemichannels with cancer in diverse models and comment on the current technical limitations for their study.
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Affiliation(s)
- Kurt A Schalper
- Servicio Anatomía Patológica, Clínica Alemana de Santiago, Facultad de Medicina Clinica Alemana Universidad del Desarrollo Santiago, Chile ; Department of Pathology, Yale School of Medicine New Haven, CT, USA
| | | | - Mauricio P Oyarzo
- Servicio Anatomía Patológica, Clínica Alemana de Santiago, Facultad de Medicina Clinica Alemana Universidad del Desarrollo Santiago, Chile
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47
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Smyth JW, Zhang SS, Sanchez JM, Lamouille S, Vogan JM, Hesketh GG, Hong T, Tomaselli GF, Shaw RM. A 14-3-3 mode-1 binding motif initiates gap junction internalization during acute cardiac ischemia. Traffic 2014; 15:684-99. [PMID: 24612377 PMCID: PMC4278178 DOI: 10.1111/tra.12169] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 03/05/2014] [Accepted: 03/05/2014] [Indexed: 02/03/2023]
Abstract
Altered phosphorylation and trafficking of connexin 43 (Cx43) during acute ischemia contributes to arrhythmogenic gap junction remodeling, yet the critical sequence and accessory proteins necessary for Cx43 internalization remain unresolved. 14-3-3 proteins can regulate protein trafficking, and a 14-3-3 mode-1 binding motif is activated upon phosphorylation of Ser373 of the Cx43 C-terminus. We hypothesized that Cx43(Ser373) phosphorylation is important to pathological gap junction remodeling. Immunofluorescence in human heart reveals the enrichment of 14-3-3 proteins at intercalated discs, suggesting interaction with gap junctions. Knockdown of 14-3-3τ in cell lines increases gap junction plaque size at cell-cell borders. Cx43(S373A) mutation prevents Cx43/14-3-3 complexing and stabilizes Cx43 at the cell surface, indicating avoidance of degradation. Using Langendorff-perfused mouse hearts, we detect phosphorylation of newly internalized Cx43 at Ser373 and Ser368 within 30 min of no-flow ischemia. Phosphorylation of Cx43 at Ser368 by protein kinase C and Ser255 by mitogen-activated protein kinase has previously been implicated in Cx43 internalization. The Cx43(S373A) mutant is resistant to phosphorylation at both these residues and does not undergo ubiquitination, revealing Ser373 phosphorylation as an upstream gatekeeper of a posttranslational modification cascade necessary for Cx43 internalization. Cx43(Ser373) phosphorylation is a potent target for therapeutic interventions to preserve gap junction coupling in the stressed myocardium.
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Affiliation(s)
- James W. Smyth
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center
| | - Shan-Shan Zhang
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center
| | - Jose M. Sanchez
- Department of Medicine, University of California San Francisco
| | - Samy Lamouille
- Department of Medicine, University of California San Francisco
| | - Jacob M. Vogan
- Department of Medicine, University of California San Francisco
| | | | - TingTing Hong
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center
- Department of Medicine, University of California Los Angeles
| | | | - Robin M. Shaw
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center
- Department of Medicine, University of California Los Angeles
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Cea LA, Riquelme MA, Vargas AA, Urrutia C, Sáez JC. Pannexin 1 channels in skeletal muscles. Front Physiol 2014; 5:139. [PMID: 24782784 PMCID: PMC3990038 DOI: 10.3389/fphys.2014.00139] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 03/21/2014] [Indexed: 11/13/2022] Open
Abstract
Normal myotubes and adult innervated skeletal myofibers express the glycoprotein pannexin1 (Panx1). Six of them form a “gap junction hemichannel-like” structure that connects the cytoplasm with the extracellular space; here they will be called Panx1 channels. These are poorly selective channels permeable to ions, small metabolic substrate, and signaling molecules. So far little is known about the role of Panx1 channels in muscles but skeletal muscles of Panx1−/− mice do not show an evident phenotype. Innervated adult fast and slow skeletal myofibers show Panx1 reactivity in close proximity to dihydropyridine receptors in the sarcolemma of T-tubules. These Panx1 channels are activated by electrical stimulation and extracellular ATP. Panx1 channels play a relevant role in potentiation of muscle contraction because they allow release of ATP and uptake of glucose, two molecules required for this response. In support of this notion, the absence of Panx1 abrogates the potentiation of muscle contraction elicited by repetitive electrical stimulation, which is reversed by exogenously applied ATP. Phosphorylation of Panx1 Thr and Ser residues might be involved in Panx1 channel activation since it is enhanced during potentiation of muscle contraction. Under denervation, Panx1 levels are upregulated and this partially explains the reduction in electrochemical gradient, however its absence does not prevent denervation-induced atrophy but prevents the higher oxidative state. Panx1 also forms functional channels at the cell surface of myotubes and their functional state has been associated with intracellular Ca2+ signals and regulation of myotube plasticity evoked by electrical stimulation. We proposed that Panx1 channels participate as ATP channels and help to keep a normal oxidative state in skeletal muscles.
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Affiliation(s)
- Luis A Cea
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile ; Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Manuel A Riquelme
- Department of Biochemistry, University of Texas Health Science Center San Antonio, TX, USA
| | - Anibal A Vargas
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile ; Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Carolina Urrutia
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile ; Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
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49
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Grek CL, Rhett JM, Ghatnekar GS. Cardiac to cancer: connecting connexins to clinical opportunity. FEBS Lett 2014; 588:1349-64. [PMID: 24607540 DOI: 10.1016/j.febslet.2014.02.047] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 02/25/2014] [Accepted: 02/26/2014] [Indexed: 12/26/2022]
Abstract
Gap junctions and their connexin components are indispensable in mediating the cellular coordination required for tissue and organ homeostasis. The critical nature of their existence mandates a connection to disease while at the same time offering therapeutic potential. Therapeutic intervention may be offered through the pharmacological and molecular disruption of the pathways involved in connexin biosynthesis, gap junction assembly, stabilization, or degradation. Chemical inhibitors aimed at closing connexin channels, peptide mimetics corresponding to short connexin sequences, and gene therapy approaches have been incredibly useful molecular tools in deciphering the complexities associated with connexin biology. Recently, therapeutic potential in targeting connexins has evolved from basic research in cell-based models to clinical opportunity in the form of human trials. Clinical promise is particularly evident with regards to targeting connexin43 in the context of wound healing. The following review is aimed at highlighting novel advances where the pharmacological manipulation of connexin biology has proven beneficial in animals or humans.
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Affiliation(s)
- Christina L Grek
- FirstString Research, Inc., 300 W. Coleman Blvd., Suite 203, Mount Pleasant, SC, United States
| | - J Matthew Rhett
- Department of Surgery, Division of General Surgery, Medical University of South Carolina, Charleston, SC, United States
| | - Gautam S Ghatnekar
- FirstString Research, Inc., 300 W. Coleman Blvd., Suite 203, Mount Pleasant, SC, United States.
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Retamal MA. Connexin and Pannexin hemichannels are regulated by redox potential. Front Physiol 2014; 5:80. [PMID: 24611056 PMCID: PMC3933782 DOI: 10.3389/fphys.2014.00080] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/08/2014] [Indexed: 01/28/2023] Open
Abstract
Connexins (Cxs) and Pannexins (Panxs) are two non-related protein families, having both the property to form hemichannels at the plasma membrane. There are 21 genes coding for different Cx based proteins and only 3 for Panx. Under physiological conditions, these hemichannels (Cxs and Panxs) present a low open probability, but when open, they allow the release of signaling molecules to the extracellular space. However, under pathological conditions, these hemichannels increase their open probability, inducing important lysis of metabolites, and ionic imbalance, which in turn induce the massive entry of Ca+2 to the cell. Actually, it is well recognized that Cxs and Panxs based channels play an important role in several diseases and -in many cases- this is associated with an aberrant hemichannel opening. Hemichannel opening and closing are controlled by a plethora of signaling including changes of the voltage plasma membrane, protein-protein interactions, and several posttranslational modifications, including protein cleavage, phosphorylation, glycosylation, hydroxylation and S-nitrosylation, among others. In particular, it has been recently shown that the cellular redox status modulates the opening/closing and permeability of at least Cx43, Cx46, and Panx1 hemichannels. Thus, for example, the gaseous transmitter nitric oxide (NO) can induce the S-nitrosylation of these proteins modulating in turn several of their properties. The reason is that the redox status of a cell is fundamental to set their response to the environment and also plays an important role in several pathologies. In this review, I will discuss how NO and other molecules associated with redox signaling modulate Cxs and Panx hemichannels properties.
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Affiliation(s)
- Mauricio A Retamal
- Facultad de Medicina Clínica Alemana, Centro de Fisiología Celular e Integrativa, Universidad del Desarrollo Santiago, Chile
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