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Zhou M, Zheng M, Zhou X, Tian S, Yang X, Ning Y, Li Y, Zhang S. The roles of connexins and gap junctions in the progression of cancer. Cell Commun Signal 2023; 21:8. [PMID: 36639804 PMCID: PMC9837928 DOI: 10.1186/s12964-022-01009-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/03/2022] [Indexed: 01/15/2023] Open
Abstract
Gap junctions (GJs), which are composed of connexins (Cxs), provide channels for direct information exchange between cells. Cx expression has a strong spatial specificity; however, its influence on cell behavior and information exchange between cells cannot be ignored. A variety of factors in organisms can modulate Cxs and subsequently trigger a series of responses that have important effects on cellular behavior. The expression and function of Cxs and the number and function of GJs are in dynamic change. Cxs have been characterized as tumor suppressors in the past, but recent studies have highlighted the critical roles of Cxs and GJs in cancer pathogenesis. The complex mechanism underlying Cx and GJ involvement in cancer development is a major obstacle to the evolution of therapy targeting Cxs. In this paper, we review the post-translational modifications of Cxs, the interactions of Cxs with several chaperone proteins, and the effects of Cxs and GJs on cancer. Video Abstract.
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Affiliation(s)
- Mingming Zhou
- grid.265021.20000 0000 9792 1228Graduate School, Tianjin Medical University, Tianjin, 300070 People’s Republic of China
| | - Minying Zheng
- Department of Pathology, Tianjin Union Medical Center, Nankai University, Tianjin, 300121 People’s Republic of China
| | - Xinyue Zhou
- grid.265021.20000 0000 9792 1228Graduate School, Tianjin Medical University, Tianjin, 300070 People’s Republic of China
| | - Shifeng Tian
- grid.265021.20000 0000 9792 1228Graduate School, Tianjin Medical University, Tianjin, 300070 People’s Republic of China
| | - Xiaohui Yang
- grid.216938.70000 0000 9878 7032Nankai University School of Medicine, Nankai University, Tianjin, 300071 People’s Republic of China
| | - Yidi Ning
- grid.216938.70000 0000 9878 7032Nankai University School of Medicine, Nankai University, Tianjin, 300071 People’s Republic of China
| | - Yuwei Li
- grid.417031.00000 0004 1799 2675Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, 300121 People’s Republic of China
| | - Shiwu Zhang
- Department of Pathology, Tianjin Union Medical Center, Nankai University, Tianjin, 300121 People’s Republic of China
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Wu L, Dong A, Dong L, Wang SQ, Li Y. PARIS, an optogenetic method for functionally mapping gap junctions. eLife 2019; 8:43366. [PMID: 30638447 PMCID: PMC6396999 DOI: 10.7554/elife.43366] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 01/12/2019] [Indexed: 12/29/2022] Open
Abstract
Cell-cell communication via gap junctions regulates a wide range of physiological processes by enabling the direct intercellular electrical and chemical coupling. However, the in vivo distribution and function of gap junctions remain poorly understood, partly due to the lack of non-invasive tools with both cell-type specificity and high spatiotemporal resolution. Here, we developed PARIS (pairing actuators and receivers to optically isolate gap junctions), a new fully genetically encoded tool for measuring the cell-specific gap junctional coupling (GJC). PARIS successfully enabled monitoring of GJC in several cultured cell lines under physiologically relevant conditions and in distinct genetically defined neurons in Drosophila brain, with ~10 s temporal resolution and sub-cellular spatial resolution. These results demonstrate that PARIS is a robust, highly sensitive tool for mapping functional gap junctions and study their regulation in both health and disease. For the tissues and organs of our bodies to work properly, the cells within them need to communicate with each other. One important part of cellular communication is the movement of signals – usually small molecules or ions – directly from one cell to another. This happens via structures called gap junctions, a type of sealed ‘channel’ that connects two cells. Gap junctions are found throughout the body, but investigating their precise roles in health and disease has been difficult. This is due to problems with the tools available to detect and monitor gap junctions. Some are simply harmful to cells, while others cannot be restricted to specific cell populations within a tissue. This lack of specificity makes it difficult to study gap junctions in the brain, where it is important to understand the connectivity patterns between distinct types of nerve cells. Wu et al. wanted to develop a new, non-harmful method to track gap junctions in distinct groups of cells within living tissues. To do this, Wu et al. devised PARIS, a two-part, genetically encoded system. The first part comprises a light-sensitive molecular ‘pump’, which can only be turned on by shining a laser onto the cell of interest. When the pump is active, it transports hydrogen ions out of the cell. The second part of the system is a fluorescent sensor, present inside ‘receiving’ cells, which responds to the outcoming hydrogen ions (small enough to pass through gap junctions). If an illuminated ‘signaling’ cell is connected via gap junctions to cells containing the fluorescent sensor, they will light up within seconds, but other cells not connected through gap junctions will not. The researchers first tested PARIS in cultured human and rat cells that had been genetically engineered to produce both components of the system. The experiments confirmed that PARIS could both detect networks of gap junctions in healthy cells and reveal when these networks had been disrupted, for instance by drugs or genetic mutations. Experiments using fruit flies demonstrated that PARIS was stable in living tissue and could also map the gap junctions connecting specific groups of nerve cells. PARIS is a valuable addition to the toolbox available to study cell communication. In the future, it could help increase our understanding of diseases characterized by defective gap junctions, such as seizures, cardiac irregularities, and even some cancers.
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Affiliation(s)
- Ling Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Ao Dong
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Liting Dong
- Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Shi-Qiang Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China.,Chinese Institute for Brain Research, Beijing, China
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Yin X, Feng L, Ma D, Yin P, Wang X, Hou S, Hao Y, Zhang J, Xin M, Feng J. Roles of astrocytic connexin-43, hemichannels, and gap junctions in oxygen-glucose deprivation/reperfusion injury induced neuroinflammation and the possible regulatory mechanisms of salvianolic acid B and carbenoxolone. J Neuroinflammation 2018; 15:97. [PMID: 29587860 PMCID: PMC5872583 DOI: 10.1186/s12974-018-1127-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/12/2018] [Indexed: 02/07/2023] Open
Abstract
Background Glia-mediated neuroinflammation is related to brain injury exacerbation after cerebral ischemia/reperfusion (I/R) injury. Astrocytic hemichannels or gap junctions, which were mainly formed by connexin-43, have been implicated in I/R damage. However, the exact roles of astrocytic hemichannels and gap junction in neuroinflammatory responses induced by I/R injury remain unknown. Methods Primary cultured astrocytes were subjected to OGD/R injury, an in vitro model of I/R injury. Salvianolic acid B (SalB) or carbenoxolone (CBX) were applied for those astrocytes. Besides, Cx43 mimetic peptides Gap19 or Gap26 were also applied during OGD/R injury; Cx43 protein levels were determined by western blot and cytoimmunofluorescene staining, hemichannel activities by Ethidium bromide uptake and ATP concentration detection, and gap junction intercellular communication (GJIC) permeability by parachute assay. Further, astrocyte-conditioned medium (ACM) was collected and incubated with microglia. Meanwhile, ATP or apyrase were applied to explore the role of ATP during OGD/R injury. Microglial activation, M1/M2 phenotypes, and M1/M2-related cytokines were detected. Also, microglia-conditioned medium (MEM) was collected and incubated with astrocytes to further investigate its influence on astrocytic hemichannel activity and GJIC permeability. Lastly, effects of ACM and MCM on neuronal viability were detected by flow cytometry. Results We found that OGD/R induced abnormally opened hemichannels with increased ATP release and EtBr uptake but reduced GJIC permeability. WB tests showed decreased astrocytic plasma membrane’s Cx43, while showing an increase in cytoplasma. Treating OGD/R-injured microglia with ATP or OGD/R-ACM induced further microglial activation and secondary pro-inflammatory cytokine release, with the M1 phenotype predominating. Conversely, astrocytes incubated with OGD/R-MCM exhibited increased hemichannel opening but reduced GJIC coupling. Both SalB and CBX inhibited abnormal astrocytic hemichannel opening and ATP release and switched the activated microglial phenotype from M1 to M2, thus providing effective neuroprotection. Application of Gap19 or Gap26 showed similar results with CBX. We also found that OGD/R injury caused both plasma membrane p-Cx43(Ser265) and p-Src(Tyr416) significantly upregulated; application of SalB may be inhibiting Src kinase and attenuating Cx43 internalization. Meanwhile, CBX treatment induced obviously downregulation of p-Cx43(Ser368) and p-PKC(Ser729) protein levels in plasma membrane. Conclusions We propose a vicious cycle exists between astrocytic hemichannel and microglial activation after OGD/R injury, which would aggravate neuroinflammatory responses and neuronal damage. Astrocytic Cx43, hemichannels, and GJIC play critical roles in OGD/R injury-induced neuroinflammatory responses; treatment differentially targeting astrocytic Cx43, hemichannels, and GJIC may provide novel avenues for therapeutics during cerebral I/R injury. Electronic supplementary material The online version of this article (10.1186/s12974-018-1127-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiang Yin
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Liangshu Feng
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Di Ma
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Ping Yin
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Xinyu Wang
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Shuai Hou
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Yulei Hao
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Jingdian Zhang
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Meiying Xin
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China
| | - Jiachun Feng
- Department of Neurology and Neuroscience Center, the First Hospital of Jilin University, Changchun, Jilin Province, 130021, People's Republic of China.
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Yu HF, Yue ZP, Wang K, Yang ZQ, Zhang HL, Geng S, Guo B. Gja1 acts downstream of Acvr1 to regulate uterine decidualization via Hand2 in mice. J Endocrinol 2017; 233:145-157. [PMID: 28219934 DOI: 10.1530/joe-16-0583] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 02/20/2017] [Indexed: 11/08/2022]
Abstract
Although Gja1 has been proved to play an important role in uterine decidualization, its regulatory mechanism remains largely unknown. Here, we showed that Gja1 was highly expressed in the decidual cells and promoted the proliferation of uterine stromal cells and expression of Prl8a2 and Prl3c1, which were two well-known differentiation markers for decidualization. Further analysis revealed that Gja1 might act downstream of Acvr1 and cAMP to regulate the differentiation of uterine stromal cells. Administration of cAMP analog 8-Br-cAMP to Acvr1 siRNA-transfected stromal cells resulted in an obvious increase of Gja1 expression, whereas PKA inhibitor H89 impeded the induction of Gja1 elicited by Acvr1 overexpression, indicating that cAMP-PKA signal mediates the regulation of Acvr1 on Gja1 expression. In uterine stromal cells, knockdown of Gja1 blocked the cAMP induction of Hand2 Moreover, siRNA-mediated downregulation of Hand2 impaired the stimulatory effects of Gja1 overexpression on the expression of Prl8a2 and Prl3c1, whereas constitutive expression of Hand2 reversed the inhibitory effects of Gja1 siRNA on stromal differentiation. Meanwhile, Gja1 might play a vital role in the crosstalk between Acvr1 and Hand2 Collectively, Gja1 may act downstream of cAMP-PKA signal to mediate the effects of Acvr1 on the differentiation of uterine stromal cells through targeting Hand2.
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Affiliation(s)
- Hai-Fan Yu
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
| | - Zhan-Peng Yue
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
| | - Kai Wang
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
| | - Zhan-Qing Yang
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
| | - Hong-Liang Zhang
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
| | - Shuang Geng
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
| | - Bin Guo
- College of Veterinary MedicineJilin University, Changchun, People's Republic of China
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Alberto AVP, Bonavita AG, Fidalgo-Neto AA, Berçot F, Alves LA. Single-cell Microinjection for Cell Communication Analysis. J Vis Exp 2017. [PMID: 28287521 DOI: 10.3791/50836] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Gap junctions are intercellular channels that allow the communication of neighboring cells. This communication depends on the contribution of a hemichannel by each neighboring cell to form the gap junction. In mammalian cells, the hemichannel is formed by six connexins, monomers with four transmembrane domains and a C and N terminal within the cytoplasm. Gap junctions permit the exchange of ions, second messengers, and small metabolites. In addition, they have important roles in many forms of cellular communication within physiological processes such as synaptic transmission, heart contraction, cell growth and differentiation. We detail how to perform a single-cell microinjection of Lucifer Yellow to visualize cellular communication via gap-junctions in living cells. It is expected that in functional gap junctions, the dye will diffuse from the loaded cell to the connected cells. It is a very useful technique to study gap junctions since you can evaluate the diffusion of the fluorescence in real time. We discuss how to prepare the cells and the micropipette, how to use a micromanipulator and inject a low molecular weight fluorescent dye in an epithelial cell line.
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Affiliation(s)
| | - André G Bonavita
- Institute Oswaldo Cruz, Laboratory of Cellular Communication, Oswaldo Cruz Foundation
| | | | - Filipe Berçot
- Institute Oswaldo Cruz, Laboratory of Cellular Communication, Oswaldo Cruz Foundation
| | - Luiz A Alves
- Institute Oswaldo Cruz, Laboratory of Cellular Communication, Oswaldo Cruz Foundation;
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Zhu Y, Gao Y, Tao C, Shao M, Zhao S, Huang W, Yao T, Johnson JA, Liu T, Cypess AM, Gupta O, Holland WL, Gupta RK, Spray DC, Tanowitz HB, Cao L, Lynes MD, Tseng YH, Elmquist JK, Williams KW, Lin HV, Scherer PE. Connexin 43 Mediates White Adipose Tissue Beiging by Facilitating the Propagation of Sympathetic Neuronal Signals. Cell Metab 2016; 24:420-433. [PMID: 27626200 PMCID: PMC5024720 DOI: 10.1016/j.cmet.2016.08.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/28/2016] [Accepted: 08/10/2016] [Indexed: 01/09/2023]
Abstract
"Beige" adipocytes reside in white adipose tissue (WAT) and dissipate energy as heat. Several studies have shown that cold temperature can activate pro-opiomelanocortin-expressing (POMC) neurons and increase sympathetic neuronal tone to regulate WAT beiging. WAT, however, is traditionally known to be sparsely innervated. Details regarding the neuronal innervation and, more importantly, the propagation of the signal within the population of "beige" adipocytes are sparse. Here, we demonstrate that beige adipocytes display an increased cell-to-cell coupling via connexin 43 (Cx43) gap junction channels. Blocking of Cx43 channels by 18α-glycyrrhetinic acid decreases POMC-activation-induced adipose tissue beiging. Adipocyte-specific deletion of Cx43 reduces WAT beiging to a level similar to that observed in denervated fat pads. In contrast, overexpression of Cx43 is sufficient to promote beiging even with mild cold stimuli. These data reveal the importance of cell-to-cell communication, effective in cold-induced WAT beiging, for the propagation of limited neuronal inputs in adipose tissue.
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Affiliation(s)
- Yi Zhu
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Yong Gao
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; National Laboratory of Medical Molecular Biology, Institute of Basic Medical Science, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100005, People's Republic of China
| | - Caroline Tao
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mengle Shao
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shangang Zhao
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wei Huang
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Ting Yao
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, 76 West Yanta Road, Xi'an, Shaanxi 710061, People's Republic of China
| | - Joshua A Johnson
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tiemin Liu
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Aaron M Cypess
- Translational Physiology Section, Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Olga Gupta
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - William L Holland
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rana K Gupta
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - David C Spray
- Departments of Neuroscience and Medicine (Cardiology), Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Herbert B Tanowitz
- Departments of Pathology and Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lei Cao
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Matthew D Lynes
- Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Yu-Hua Tseng
- Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Joel K Elmquist
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kevin W Williams
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hua V Lin
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Joshi CN, Martin DN, Shaver P, Madamanchi C, Muller-Borer BJ, Tulis DA. Control of vascular smooth muscle cell growth by connexin 43. Front Physiol 2012; 3:220. [PMID: 22737133 PMCID: PMC3380337 DOI: 10.3389/fphys.2012.00220] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/01/2012] [Indexed: 12/04/2022] Open
Abstract
Connexin 43 (Cx43), the principal gap junction protein in vascular smooth muscle cells (VSMCs), regulates movement of ions and other signaling molecules through gap junction intercellular communication (GJIC) and plays important roles in maintaining normal vessel function; however, many of the signaling mechanisms controlling Cx43 in VSMCs are not clearly described. The goal of this study was to investigate mechanisms of Cx43 regulation with respect to VSMC proliferation. Treatment of rat primary VSMCs with the cAMP analog 8Br-cAMP, the soluble guanylate cyclase (sGC) stimulator BAY 41-2272 (BAY), or the Cx inducer diallyl disulfide (DADS) significantly reduced proliferation after 72 h compared with vehicle controls. Bromodeoxyuridine uptake revealed reduction (p < 0.05) in DNA synthesis after 6 h and flow cytometry showed reduced (40%) S-phase cell numbers after 16 h in DADS-treated cells compared with vehicle controls. Cx43 expression significantly increased after 270 min treatment with 8Br-cAMP, 8Br-cGMP, BAY or DADS. Inhibition of PKA, PKG or PKC reversed 8Br-cAMP-stimulated increases in Cx43 expression, whereas only PKG or PKC inhibition reversed 8Br-cGMP- and BAY-stimulated increases in total Cx43. Interestingly, stimulation of Cx43 expression by DADS was not dependent on PKA, PKG or PKC. Using fluorescence recovery after photobleaching, only 8Br-cAMP or DADS increased GJIC with 8Br-cAMP mediated by PKC and DADS mediated by PKG. Further, DADS significantly increased phosphorylation at MAPK-sensitive Serine (Ser)255 and Ser279, the cell cycle regulatory kinase-sensitive Ser262 and PKC-sensitive Ser368 after 30 min while 8Br-cAMP significantly increased phosphorylation only at Ser279 compared with controls. This study demonstrates that 8Br-cAMP- and DADS-enhanced GJIC rather than Cx43 expression and/or phosphorylation plays important roles in the regulation of VSMC proliferation and provides new insights into the growth-regulatory capacities of Cx43 in VSM.
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Affiliation(s)
- Chintamani N Joshi
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
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Piccoli C, D'Aprile A, Scrima R, Ambrosi L, Zefferino R, Capitanio N. Subcytotoxic mercury chloride inhibits gap junction intercellular communication by a redox- and phosphorylation-mediated mechanism. Free Radic Biol Med 2012; 52:916-27. [PMID: 22240155 DOI: 10.1016/j.freeradbiomed.2011.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 12/09/2011] [Accepted: 12/20/2011] [Indexed: 11/26/2022]
Abstract
Gap junctions play a central role in coordinating intercellular signal-transduction pathways to control tissue homeostasis. Deregulation of gap junctional intercellular communication is a common phenotype of cancer cells and supports its involvement in the carcinogenesis process. Many carcinogens, like environmental heavy-metal chemical pollutants, are known to activate various signal transduction mechanisms and modulate GJIC. They act as tumor promoters on preexisting "initiated" cells, rather than as genotoxic initiators, albeit their mode of action is often unknown. In this study we investigated the effect of Hg(II) (HgCl(2)) on GJIC in cultured human keratinocytes. It is shown that subcytotoxic concentrations of HgCl(2) as low as 10 nM cause inhibition of the GJIC, assessed by dye transfer assay, despite enhanced expression of connexins. In addition, HgCl(2)-treated keratinocytes exhibited a decrease of free thiols and accumulation of mitochondria-derived reactive oxygen species, albeit no effect on the respiratory chain activity was observed. Treatment of HgCl(2)-exposed keratinocytes with the PKC inhibitor calphostin C and with all-trans retinoic acid resulted in rescue of the mitochondrial ROS overproduction and full recovery of the GJIC. Similar results were obtained with the PKA activator db-cAMP. Overall, the presented results support a cross-talk between the altered intracellular redox tone and PKA- and PKC-mediated signaling in HgCl(2)-challenged keratinocytes. These events, although not cytotoxic, lead to inhibition of GJIC and possibly to carcinogenic priming.
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Affiliation(s)
- Claudia Piccoli
- Department of Biomedical Sciences, University of Foggia, Foggia, Italy
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