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Cardouat G, Douard M, Bouchet C, Roubenne L, Kmecová Z, Esteves P, Brette F, Guignabert C, Tu L, Campagnac M, Robillard P, Coste F, Delcambre F, Thumerel M, Begueret H, Maurac A, Belaroussi Y, Klimas J, Ducret T, Quignard JF, Vacher P, Baudrimont I, Marthan R, Berger P, Guibert C, Freund-Michel V. NGF increases Connexin-43 expression and function in pulmonary arterial smooth muscle cells to induce pulmonary artery hyperreactivity. Biomed Pharmacother 2024; 174:116552. [PMID: 38599061 DOI: 10.1016/j.biopha.2024.116552] [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: 11/26/2023] [Revised: 03/30/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024] Open
Abstract
AIMS Pulmonary hypertension (PH) is characterised by an increase in pulmonary arterial pressure, ultimately leading to right ventricular failure and death. We have previously shown that nerve growth factor (NGF) plays a critical role in PH. Our objectives here were to determine whether NGF controls Connexin-43 (Cx43) expression and function in the pulmonary arterial smooth muscle, and whether this mechanism contributes to NGF-induced pulmonary artery hyperreactivity. METHODS AND RESULTS NGF activates its TrkA receptor to increase Cx43 expression, phosphorylation, and localization at the plasma membrane in human pulmonary arterial smooth muscle cells, thus leading to enhanced activity of Cx43-dependent GAP junctions as shown by Lucifer Yellow dye assay transfer and fluorescence recovery after photobleaching -FRAP- experiments. Using both in vitro pharmacological and in vivo SiRNA approaches, we demonstrate that NGF-dependent increase in Cx43 expression and activity in the rat pulmonary circulation causes pulmonary artery hyperreactivity. We also show that, in a rat model of PH induced by chronic hypoxia, in vivo blockade of NGF or of its TrkA receptor significantly reduces Cx43 increased pulmonary arterial expression induced by chronic hypoxia and displays preventive effects on pulmonary arterial pressure increase and right heart hypertrophy. CONCLUSIONS Modulation of Cx43 by NGF in pulmonary arterial smooth muscle cells contributes to NGF-induced alterations of pulmonary artery reactivity. Since NGF and its TrkA receptor play a role in vivo in Cx43 increased expression in PH induced by chronic hypoxia, these NGF/Cx43-dependent mechanisms may therefore play a significant role in human PH pathophysiology.
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MESH Headings
- Animals
- Humans
- Male
- Rats
- Cells, Cultured
- Connexin 43/metabolism
- Gap Junctions/metabolism
- Gap Junctions/drug effects
- Hypertension, Pulmonary/metabolism
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/drug effects
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/drug effects
- Nerve Growth Factor/metabolism
- Phosphorylation
- Pulmonary Artery/drug effects
- Pulmonary Artery/metabolism
- Pulmonary Artery/pathology
- Rats, Sprague-Dawley
- Rats, Wistar
- Receptor, trkA/metabolism
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Affiliation(s)
| | - Matthieu Douard
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France; Univ. Bordeaux, INSERM, CRCTB, U 1045, IHU Liryc, Bordeaux F-33000, France
| | - Clément Bouchet
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France
| | - Lukas Roubenne
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France
| | - Zuzana Kmecová
- Department of Pharmacology and Toxicology, Comenius University, Bratislava, Slovakia
| | - Pauline Esteves
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France
| | - Fabien Brette
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France; Univ. Bordeaux, INSERM, CRCTB, U 1045, IHU Liryc, Bordeaux F-33000, France
| | - Christophe Guignabert
- INSERM UMR_S 999, « Pulmonary Hypertension: Pathophysiology and Novel Therapies », Hôpital Marie Lannelongue, Le Plessis-Robinson 92350, France; Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre 94270, France
| | - Ly Tu
- INSERM UMR_S 999, « Pulmonary Hypertension: Pathophysiology and Novel Therapies », Hôpital Marie Lannelongue, Le Plessis-Robinson 92350, France; Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre 94270, France
| | | | - Paul Robillard
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France
| | - Florence Coste
- Laboratoire de Pharm-écologie Cardiovasculaire (LaPEC-EA 4278), Université d'Avignon et des Pays du Vaucluse, Avignon 84000, France
| | | | - Matthieu Thumerel
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France; CHU de Bordeaux, Bordeaux 33000, France
| | | | | | | | - Jan Klimas
- Department of Pharmacology and Toxicology, Comenius University, Bratislava, Slovakia
| | - Thomas Ducret
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France
| | | | - Pierre Vacher
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France
| | | | - Roger Marthan
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France; CHU de Bordeaux, Bordeaux 33000, France
| | - Patrick Berger
- Univ. Bordeaux, INSERM, CRCTB, U 1045, Bordeaux F-33000, France; CHU de Bordeaux, Bordeaux 33000, France
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Zhao M, Subudeng G, Zhao Y, Hao S, Li H. Effect of Cyclic Adenosine Monophosphate on Connexin 37 Expression in Sheep Cumulus-Oocyte Complexes. J Dev Biol 2024; 12:10. [PMID: 38651455 PMCID: PMC11036199 DOI: 10.3390/jdb12020010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/10/2024] [Accepted: 03/26/2024] [Indexed: 04/25/2024] Open
Abstract
Gap junctional connection (GJC) in the cumulus-oocyte complex (COC) provides necessary support for message communication and nutrient transmission required for mammalian oocyte maturation. Cyclic adenosine monophosphate (cAMP) is not only a prerequisite for regulating oocyte meiosis, but also the key intercellular factor for affecting GJC function in COCs. However, there are no reports on whether cAMP regulates connexin 37 (Cx37) expression, one of the main connexin proteins, in sheep COCs. In this study, the expression of Cx37 protein and gene in immature sheep COC was detected using immunohistochemistry and PCR. Subsequently, the effect of cAMP on Cx37 expression in sheep COCs cultured in a gonadotropin-free culture system for 10 min or 60 min was evaluated using competitive ELISA, real-time fluorescent quantitative PCR (RT-qPCR), and Western blot. The results showed that the Cx37 protein was present in sheep oocytes and cumulus cells; the same results were found with respect to GJA4 gene expression. In the gonadotropin-free culture system, compared to the control, significantly higher levels of cAMP as well as Cx37 gene and protein expression were found in sheep COCs following treatment in vitro with Forskolin and IBMX (100 μM and 500 μM)) for 10 min (p < 0.05). Compared to the controls (at 10 or 60 min), cAMP levels in sheep COCs were significantly elevated as a result of Forskolin and IBMX treatment (p < 0.05). Following culturing in vitro for 10 min or 60 min, Forskolin and IBMX treatment can significantly promote Cx37 expression in sheep COCs (p < 0.05), a phenomenon which can be counteracted when the culture media is supplemented with RP-cAMP, a cAMP-specific competitive inhibitor operating through suppression of the protein kinase A (PKA). In summary, this study reports the preliminary regulatory mechanism of cAMP involved in Cx37 expression for the first time, and provides a novel explanation for the interaction between cAMP and GJC communication during sheep COC culturing in vitro.
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Affiliation(s)
- Mengyao Zhao
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China; (M.Z.); (G.S.); (Y.Z.); (S.H.)
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Inner Mongolia Agricultural University, Hohhot 010018, China
- Key Laboratory of Animal Embryo and Development Engineering of Autonomous Region Universities, Hohhot 010018, China
| | - Gerile Subudeng
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China; (M.Z.); (G.S.); (Y.Z.); (S.H.)
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Yufen Zhao
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China; (M.Z.); (G.S.); (Y.Z.); (S.H.)
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Shaoyu Hao
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China; (M.Z.); (G.S.); (Y.Z.); (S.H.)
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Haijun Li
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China; (M.Z.); (G.S.); (Y.Z.); (S.H.)
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Inner Mongolia Agricultural University, Hohhot 010018, China
- Key Laboratory of Animal Embryo and Development Engineering of Autonomous Region Universities, Hohhot 010018, China
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Zhao GL, Zhou H, Guo YH, Zhong SM, Zhou H, Li F, Lei B, Wang Z, Miao Y. Modulation of Rac1/PAK1/connexin43-mediated ATP release from astrocytes contributes to retinal ganglion cell survival in experimental glaucoma. Glia 2023; 71:1502-1521. [PMID: 36794533 DOI: 10.1002/glia.24354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/17/2023]
Abstract
Connexin43 (Cx43) is a major gap junction protein in glial cells. Mutations have been found in the gap-junction alpha 1 gene encoding Cx43 in glaucomatous human retinas, suggestive of the involvement of Cx43 in the pathogenesis of glaucoma. However, how Cx43 is involved in glaucoma is still unknown. We showed that increased intraocular pressure in a glaucoma mouse model of chronic ocular hypertension (COH) downregulated Cx43, which was mainly expressed in retinal astrocytes. Astrocytes in the optic nerve head where they gather and wrap the axons (optic nerve) of retinal ganglion cells (RGCs) were activated earlier than neurons in COH retinas and the alterations in astrocytes plasticity in the optic nerve caused a reduction in Cx43 expression. A time course showed that reductions of Cx43 expression were correlated with the activation of Rac1, a member of the Rho family. Co-immunoprecipitation assays showed that active Rac1, or the downstream signaling effector PAK1, negatively regulated Cx43 expression, Cx43 hemichannel opening and astrocyte activation. Pharmacological inhibition of Rac1 stimulated Cx43 hemichannel opening and ATP release, and astrocytes were identified to be one of the main sources of ATP. Furthermore, conditional knockout of Rac1 in astrocytes enhanced Cx43 expression and ATP release, and promoted RGC survival by upregulating the adenosine A3 receptor in RGCs. Our study provides new insight into the relationship between Cx43 and glaucoma, and suggests that regulating the interaction between astrocytes and RGCs via the Rac1/PAK1/Cx43/ATP pathway may be used as part of a therapeutic strategy for managing glaucoma.
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Affiliation(s)
- Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Hong Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yun-Hui Guo
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Shu-Min Zhong
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Han Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Bo Lei
- Institute of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
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Sedovy MW, Leng X, Leaf MR, Iqbal F, Payne LB, Chappell JC, Johnstone SR. Connexin 43 across the Vasculature: Gap Junctions and Beyond. J Vasc Res 2022; 60:101-113. [PMID: 36513042 PMCID: PMC11073551 DOI: 10.1159/000527469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/26/2022] [Indexed: 12/15/2022] Open
Abstract
Connexin 43 (Cx43) is essential to the function of the vasculature. Cx43 proteins form gap junctions that allow for the exchange of ions and molecules between vascular cells to facilitate cell-to-cell signaling and coordinate vasomotor activity. Cx43 also has intracellular signaling functions that influence vascular cell proliferation and migration. Cx43 is expressed in all vascular cell types, although its expression and function vary by vessel size and location. This includes expression in vascular smooth muscle cells (vSMC), endothelial cells (EC), and pericytes. Cx43 is thought to coordinate homocellular signaling within EC and vSMC. Cx43 gap junctions also function as conduits between different cell types (heterocellular signaling), between EC and vSMC at the myoendothelial junction, and between pericyte and EC in capillaries. Alterations in Cx43 expression, localization, and post-translational modification have been identified in vascular disease states, including atherosclerosis, hypertension, and diabetes. In this review, we discuss the current understanding of Cx43 localization and function in healthy and diseased blood vessels across all vascular beds.
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Affiliation(s)
- Meghan W. Sedovy
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
- Translational Biology, Medicine, And Health Graduate Program, Virginia Tech, Blacksburg, VA, USA
| | - Xinyan Leng
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
| | - Melissa R. Leaf
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
| | - Farwah Iqbal
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
| | - Laura Beth Payne
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
| | - John C. Chappell
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
| | - Scott R. Johnstone
- The Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, 4 Riverside Circle, Roanoke, VA, USA
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
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5
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Connexins and cAMP Cross-Talk in Cancer Progression and Metastasis. Cancers (Basel) 2020; 13:cancers13010058. [PMID: 33379194 PMCID: PMC7795795 DOI: 10.3390/cancers13010058] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 02/06/2023] Open
Abstract
Simple Summary Different connexins play diverse roles in cancers, either tumor-suppressing or tumor-promoting. In lung cancer, Cx43 serves as a tumor suppressor at the early stage, but it can also be a tumor-promotor at an advanced stage and during metastasis. Moreover, other connexins, including Cx26, Cx31.1, and Cx32, can be tumor suppressors. In contrast, Cx30.3 can be a tumor-promotor. The roles of different connexins in different cancers have also been established. Cx43 acts as a tumor suppressor in colorectal cancer, breast cancer, and glioma, whereas Cx32 can be a suppressor in liver tumors and hepatocarcinogenesis. Cx26 can be a tumor suppressor in mammary tumors; in contrast, it can be a tumor-promotor in melanoma. Existing drugs/molecules targeting the cAMP/PKA/connexin axis act to regulate channel opening/closing. Mimic peptides, such as Gap19, Gap26, and Gap 27 block hemichannels, mimetic peptides, and CT9/CT10 and promote hemichannel opening and also hemichannel closing. Abstract Connexin-containing gap junctions mediate the direct exchange of small molecules between cells, thus promoting cell–cell communication. Connexins (Cxs) have been widely studied as key tumor-suppressors. However, certain Cx subtypes, such as Cx43 and Cx26, are overexpressed in metastatic tumor lesions. Cyclic adenosine monophosphate (cAMP) signaling regulates Cx expression and function via transcriptional control and phosphorylation. cAMP also passes through gap junction channels between adjacent cells, regulating cell cycle progression, particularly in cancer cell populations. Low levels of cAMP are sufficient to activate key effectors. The present review evaluates the mechanisms underlying Cx regulation by cAMP signaling and the role of gap junctions in cancer progression and metastasis. A deeper understanding of these processes might facilitate the development of novel anticancer drugs.
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Chen R, Chen Y, Yuan Y, Zou X, Sun Q, Lin H, Chen X, Liu M, Deng Z, Yao Y, Guo D, Zhang Y. Cx43 and AKAP95 regulate G1/S conversion by competitively binding to cyclin E1/E2 in lung cancer cells. Thorac Cancer 2020; 11:1594-1602. [PMID: 32338437 PMCID: PMC7262948 DOI: 10.1111/1759-7714.13435] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 01/09/2023] Open
Abstract
Background This study aimed to overexpress or silence connexin 43 (Cx43) and A‐kinase anchoring protein 95 (AKAP95) in human A549 cells to explore their effects on cyclins and on G1/S conversion when the interrelationship of Cx43, AKAP95, and cyclin E1/E2 changes. Methods The study mainly used Western blot analysis and Co‐immuno precipitation to detect the target protein in Cx43/AKAP95 over expressed human A549 cells, and the relationship of proteins Cx43, AKAP95 and Cyclin E during G1‐S phase was explored with qualitative and quantitative analysis. Results The overexpression of Cx43 inhibited the expression of cyclin D1 and E1 by accelerating their degradation and reduced the Cdk2 activity that blocked the DNA transcription activity. However, the overexpression of AKAP95 increased the expression of cyclin D1 and E1 and inhibited their degradation, and enhanced the Cdk2 activity that promoted the DNA transcription activity. Cx43 and AKAP95 competitively bound to cyclin E1/E2, and the competitive binding affected the Cdk2 activity, Rb phosphorylation, DNA transcription activity, and G1/S conversion. Conclusions This study showed that the expression of ERK1/2, PKA, and PKB increased when BEAS‐2B cells were treated with PDGF‐BB, suggesting that ERK1/2, PKA, and PKB might be involved in the binding of AKAP95 with cyclin E, or the separation of AKAP95 from Cx43 from cyclin E1/E2. The specific mechanism underlying this process still needs further exploration.
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Affiliation(s)
- Renzhen Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Yu Chen
- School of Medicine, Xiamen University, Xiamen, China
| | - Yangyang Yuan
- Henan provincial Clinical Research Center for Perinatal Medicine, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xuan Zou
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Qian Sun
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Hongyan Lin
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Xiaoyi Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Mingda Liu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Zifeng Deng
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Youliang Yao
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Dongbei Guo
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Yongxing Zhang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
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Ezrin-anchored PKA phosphorylates serine 369 and 373 on connexin 43 to enhance gap junction assembly, communication, and cell fusion. Biochem J 2018; 475:455-476. [PMID: 29259079 DOI: 10.1042/bcj20170529] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 12/25/2022]
Abstract
A limited number of human cells can fuse to form multinucleated syncytia. In the differentiation of human placenta, mononuclear cytotrophoblasts fuse to form an endocrinologically active, non-proliferative, multinucleated syncytium. This syncytium covers the placenta and manages the exchange of nutrients and gases between maternal and fetal circulation. We recently reported protein kinase A (PKA) to be part of a macromolecular signaling complex with ezrin and gap junction protein connexin 43 (Cx43) that provides cAMP-mediated control of gap junction communication. Here, we examined the associated phosphorylation events. Inhibition of PKA activity resulted in decreased Cx43 phosphorylation, which was associated with reduced trophoblast fusion and differentiation. In vitro studies using peptide arrays, together with mass spectrometry, pointed to serine 369 and 373 of Cx43 as the major PKA phosphorylation sites that increases gap junction assembly at the plasmalemma. A combination of knockdown and reconstitution experiments and gap-fluorescence loss in photobleaching assays with mutant Cx43 containing single or double phosphoserine-mimicking amino acid substitutions in putative PKA phosphorylation sites demonstrated that phosphorylation of S369 and S373 mediated gap junction communication, trophoblast differentiation, and cell fusion.
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8
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Kong L, Wang Q, Jin J, Xiang Z, Chen T, Shen S, Wang H, Gao Q, Wang Y. Insulin resistance enhances the mitogen-activated protein kinase signaling pathway in ovarian granulosa cells. PLoS One 2017; 12:e0188029. [PMID: 29125859 PMCID: PMC5695281 DOI: 10.1371/journal.pone.0188029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/29/2017] [Indexed: 12/22/2022] Open
Abstract
The ovary is the main regulator of female fertility. Granulosa cell dysfunction may be involved in various reproductive endocrine disorders. Here we investigated the effect of insulin resistance on the metabolism and function of ovarian granulosa cells, and dissected the functional status of the mitogen-activated protein kinase signaling pathway in these cells. Our data showed that dexamethasone-induced insulin resistance in mouse granulosa cells reduced insulin sensitivity, accompanied with an increase in phosphorylation of p44/42 mitogen-activated protein kinase. Furthermore, up-regulation of cytochrome P450 subfamily 17 and testosterone and down-regulation of progesterone were observed in insulin-resistant mouse granulosa cells. Inhibition of p44/42 mitogen-activated protein kinase after induction of insulin resistance in mouse granulosa cells decreased phosphorylation of p44/42 mitogen-activated protein kinase, downregulated cytochrome P450 subfamily 17 and lowered progesterone production. This insulin resistance cell model can successfully demonstrate certain mechanisms such as hyperandrogenism, which may inspire a new strategy for treating reproductive endocrine disorders by regulating cell signaling pathways.
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Affiliation(s)
- Linghui Kong
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Qien Wang
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Jiewen Jin
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Zou Xiang
- Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hong Kong, China
| | - Taoyu Chen
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Shanmei Shen
- Divisions of Endocrinology, The Affiliated Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Hongwei Wang
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Qian Gao
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Yong Wang
- State Key Laboratory of Analytical Chemistry for Life Science & Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China
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Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
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10
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Li X, Jiang S, Yang H, Liao Q, Cao S, Yan X, Huang D. Breakthrough Cancer Pain Is Associated with Spinal Gap Junction Activation via Regulation of Connexin 43 in a Mouse Model. Front Cell Neurosci 2017; 11:207. [PMID: 28769766 PMCID: PMC5511832 DOI: 10.3389/fncel.2017.00207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/30/2017] [Indexed: 12/21/2022] Open
Abstract
Breakthrough cancer pain (BTcP) is a high-intensity, short-duration, unpredictable and uncontrollable pain. Recent studies have shown that activation of gap junction (GJ) in spinal cord plays an important role in the pathogenesis of BTcP. We examined the expressions of Glial fibrillary acidic protein (GFAP), connexin (Cx) 43 protein and phosphorylation of Cx43 (p-Cx43) in the spinal cord of mice. In addition, we investigated the effects of Gap26, a selective GJ blocker, on the expressions of GFAP, Cx43 and p-Cx43 in BTcP mice. We found that the expressions of GFAP and Cx43 proteins were significantly upregulated while p-Cx43 was down-regulated in the spinal cord in a mouse model of BTcP. The overexpression of Cx43 protein in the spinal cord increased GJ formation and enhanced BTcP. The variation of the ratio of p-Cx43/T-Cx43 (total Cx43) affected the function of GJ to induce BTcP. Furthermore, BTcP was alleviated by Gap26 via reducing pain hypersensitivity. The inhibition of Cx43 and p-Cx43 by Gap26 attenuated BTcP but the p/T ratio of Cx43 remained unchanged in BTcP mice. We reveal that the expression and phosphorylation of Cx43 affected BTcP and GJ activation facilitated BTcP via a Cx43-mediated signaling in the spinal cord. The finding may provide a scientific rationale for discovery and development of novel therapeutic targets for the treatment of BTcP clinically.
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Affiliation(s)
- Xin Li
- Department of Pain, The Third Xiangya Hospital and Institute of Pain Medicine, Central South UniversityChangsha, China
| | - Siqing Jiang
- Department of Pain, The Third Xiangya Hospital and Institute of Pain Medicine, Central South UniversityChangsha, China
| | - Hui Yang
- Department of Pain, The Third Xiangya Hospital and Institute of Pain Medicine, Central South UniversityChangsha, China
| | - Qian Liao
- Department of Pain, The Third Xiangya Hospital and Institute of Pain Medicine, Central South UniversityChangsha, China
| | - Shousong Cao
- Department of Pharmacology, School of Pharmacy, Southwest Medical UniversityLuzhou, China
| | - Xuebin Yan
- Department of Pain, The Third Xiangya Hospital and Institute of Pain Medicine, Central South UniversityChangsha, China
| | - Dong Huang
- Department of Pain, The Third Xiangya Hospital and Institute of Pain Medicine, Central South UniversityChangsha, China
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11
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Ampey BC, Ampey AC, Lopez GE, Bird IM, Magness RR. Cyclic Nucleotides Differentially Regulate Cx43 Gap Junction Function in Uterine Artery Endothelial Cells From Pregnant Ewes. Hypertension 2017; 70:401-411. [PMID: 28559397 PMCID: PMC5507815 DOI: 10.1161/hypertensionaha.117.09113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 02/03/2017] [Accepted: 05/08/2017] [Indexed: 12/20/2022]
Abstract
Supplemental Digital Content is available in the text. Cell–cell communication is dependent on GJ (gap junction) proteins such as Cx43 (connexin 43). We previously demonstrated the importance of Cx43 function in establishing the enhanced pregnancy vasodilatory phenotype during pregnancy in uterine artery endothelial cells from pregnant (P-UAEC) ewes. Cx43 is regulated by elevating cAMP and PKA (protein kinase A)–dependent Cx43 S365 phosphorylation–associated trafficking and GJ open gating, which is opposed by PKC (protein kinase C)–dependent S368 phosphorylation-mediated GJ turnover and closed gating. However, the role of cyclic nucleotide-mediated signaling mechanisms that control Cx43 and GJ function in P-UAECs is unknown. We hypothesize that cAMP will mediate increases in S365 phosphorylation, thereby, enhancing GJ trafficking and open gating, while cGMP will stimulate S368, but not S365, phosphorylation to enhance GJ turnover and closed gating in P-UAECs. Treatment with 8-Bromo (8-Br)-cAMP signal significantly (P<0.05) increased nonphosphorylated S365 signal and total Cx43 phosphorylation, but not S368 phosphorylation, while 8-Br-cGMP significantly (P<0.05) increased Cx43 C-terminus-S365 signal, S368, and total Cx43 phosphorylation. Inhibition of PKA, but not PKG (protein kinase G), abrogated the 8-Br-cAMP–stimulated increase in nonphosphorylated S365 and total Cx43 phosphorylation and inhibited S368 below basal levels, whereas inhibition of PKG blocked (P<0.05) the 8-bromo-cGMP-stimulated rises in nonphosphorylated S365, total Cx43, and S368 phosphorylation levels in P-UAECs. Functional studies showed that 8-Br-cAMP increased dye transfer and sustained calcium bursts, while 8-Br-cGMP decreased both. Thus, in P-UAECs, only 8-Br-cAMP and not 8-Br-cGMP effectively enhances nonphosphorylated S365 and total Cx43 expression that correspondingly reduces S368 phosphorylation, allowing increased GJ communication. This provides new insights into the regulatory mechanisms behind Cx43 function and GJ communication.
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Affiliation(s)
- Bryan C Ampey
- From the Department of Obstetrics and Gynecology, Perinatal Research Labs University of Wisconsin, Madison (B.C.A., A.C.A., G.E.L., I.M.B., R.R.M.); and Department of Obstetrics and Gynecology, Perinatal Research Center Tampa, University of South Florida, (R.R.M.)
| | - Amanda C Ampey
- From the Department of Obstetrics and Gynecology, Perinatal Research Labs University of Wisconsin, Madison (B.C.A., A.C.A., G.E.L., I.M.B., R.R.M.); and Department of Obstetrics and Gynecology, Perinatal Research Center Tampa, University of South Florida, (R.R.M.)
| | - Gladys E Lopez
- From the Department of Obstetrics and Gynecology, Perinatal Research Labs University of Wisconsin, Madison (B.C.A., A.C.A., G.E.L., I.M.B., R.R.M.); and Department of Obstetrics and Gynecology, Perinatal Research Center Tampa, University of South Florida, (R.R.M.)
| | - Ian M Bird
- From the Department of Obstetrics and Gynecology, Perinatal Research Labs University of Wisconsin, Madison (B.C.A., A.C.A., G.E.L., I.M.B., R.R.M.); and Department of Obstetrics and Gynecology, Perinatal Research Center Tampa, University of South Florida, (R.R.M.)
| | - Ronald R Magness
- From the Department of Obstetrics and Gynecology, Perinatal Research Labs University of Wisconsin, Madison (B.C.A., A.C.A., G.E.L., I.M.B., R.R.M.); and Department of Obstetrics and Gynecology, Perinatal Research Center Tampa, University of South Florida, (R.R.M.).
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12
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Li HJ, Sutton-McDowall ML, Wang X, Sugimura S, Thompson JG, Gilchrist RB. Extending prematuration with cAMP modulators enhances the cumulus contribution to oocyte antioxidant defence and oocyte quality via gap junctions. Hum Reprod 2016; 31:810-21. [PMID: 26908844 DOI: 10.1093/humrep/dew020] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/11/2016] [Indexed: 12/17/2022] Open
Abstract
STUDY QUESTION Can bovine oocyte antioxidant defence and oocyte quality be improved by extending the duration of pre-in vitro maturation (IVM) with cyclic adenosine mono-phosphate (cAMP) modulators? SUMMARY ANSWER Lengthening the duration of cAMP-modulated pre-IVM elevates intra-oocyte reduced glutathione (GSH) content and reduces hydrogen peroxide (H2O2) via increased cumulus cell-oocyte gap-junctional communication (GJC), associated with an improvement in subsequent embryo development and quality. WHAT IS KNOWN ALREADY Oocytes are susceptible to oxidative stress and the oocyte's most important antioxidant glutathione is supplied, at least in part, by cumulus cells. A temporary inhibition of spontaneous meiotic resumption in oocytes can be achieved by preventing a fall in cAMP, and cyclic AMP-modulated pre-IVM maintains cumulus-oocyte GJC and improves subsequent embryo development. STUDY DESIGN, SIZE, DURATION This study consisted of a series of 10 experiments using bovine oocytes in vitro, each with multiple replicates. A range of pre-IVM durations were examined as the key study treatments which were compared with a control. The study was designed to examine if one of the oocyte's major antioxidant defences can be enhanced by pre-IVM with cAMP modulators, and to examine the contribution of cumulus-oocyte GJC on these processes. PARTICIPANTS/MATERIALS, SETTING, METHODS Immature bovine cumulus-oocyte complexes were treated in vitro without (control) or with the cAMP modulators; 100 µM forskolin (FSK) and 500 µM 3-isobutyl-1-methyxanthine (IBMX), for 0, 2, 4 or 6 h (pre-IVM phase) prior to IVM. Oocyte developmental competence was assessed by embryo development and quality post-IVM/IVF. Cumulus-oocyte GJC, intra-oocyte GSH and H2O2 were quantified at various time points during pre-IVM and IVM, in the presence and the absence of functional inhibitors: carbenoxolone (CBX) to block GJC and buthionine sulfoximide (BSO) to inhibit glutathione synthesis. MAIN RESULTS AND THE ROLE OF CHANCE Pre-IVM with FSK + IBMX increased subsequent blastocyst formation rate and quality compared with standard IVM (P < 0.05), regardless of pre-IVM duration. The final blastocyst yields (proportion of blastocysts/immature oocyte) were 26.3% for the control, compared with 39.2, 35.2 and 34.2%, for the 2, 4 and 6 h pre-IVM FSK + IBMX treatments, respectively. In contrast to standard IVM (control), pre-IVM with cAMP modulators maintained open gap junctions between cumulus cells and oocytes for the duration (6 h) of pre-IVM examined, and persisted for a further 8 h in the IVM phase. Cyclic AMP-modulated pre-IVM increased intra-oocyte GSH levels at the completion of both pre-IVM and IVM, in a pre-IVM duration-dependent manner (P < 0.05), which was ablated when GJC was blocked using CBX (P < 0.05). By 4 h of pre-IVM treatment with cAMP modulators, oocyte H2O2 levels were reduced compared the control (P < 0.05), although this beneficial effect was lost when oocytes were co-treated with BSO. Inhibiting glutathione synthesis with BSO during pre-IVM ablated any positive benefits of cAMP-mediated pre-IVM on oocyte developmental competence (P < 0.01). LIMITATIONS, REASONS FOR CAUTION It is unclear if the improvement in oocyte antioxidant defence and developmental competence reported here is due to direct transfer of total and/or reduced glutathione from cumulus cells to the oocyte via gap junctions, or whether a GSH synthesis signal and/or amino acid substrates are supplied to the oocyte via gap junctions. Embryo transfer experiments are required to determine if the cAMP-mediated improvement in blastocyst rates leads to improved live birth rates. WIDER IMPLICATIONS OF THE FINDINGS IVM offers significant benefits to infertile and cancer patients and has the potential to significantly alter ART practice, if IVM efficiency in embryo production could be improved closer to that of conventional IVF (using ovarian hyperstimulation). Pre-IVM with cAMP modulators is a simple and reliable means to improve IVM outcomes. STUDY FUNDING/COMPETING INTERESTS This work was supported by grants and fellowships from the National Health and Medical Research Council of Australia (1007551, 627007, 1008137, 1023210) and by scholarships from the Chinese Scholarship Council (CSC) awarded to H.J.L. and the Japanese Society for the Promotion of Science Postdoctoral Fellowship for Research Abroad awarded to S.S. The Fluoview FV10i confocal microscope was purchased as part of the Sensing Technologies for Advanced Reproductive Research (STARR) facility, funded by the South Australian Premier's Science and Research Fund. We acknowledge partial support from the Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CE140100003). We declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
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Affiliation(s)
- H J Li
- Robinson Research Institute & School of Medicine, The University of Adelaide, Adelaide SA 5005, Australia College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - M L Sutton-McDowall
- Robinson Research Institute & School of Medicine, The University of Adelaide, Adelaide SA 5005, Australia Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Adelaide, Australia
| | - X Wang
- Robinson Research Institute & School of Medicine, The University of Adelaide, Adelaide SA 5005, Australia
| | - S Sugimura
- Robinson Research Institute & School of Medicine, The University of Adelaide, Adelaide SA 5005, Australia Department of Biological Production, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - J G Thompson
- Robinson Research Institute & School of Medicine, The University of Adelaide, Adelaide SA 5005, Australia Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Adelaide, Australia
| | - R B Gilchrist
- Robinson Research Institute & School of Medicine, The University of Adelaide, Adelaide SA 5005, Australia Discipline of Obstetrics & Gynaecology, School of Women's & Children's Health, University of New South Wales, Sydney 2013, Australia
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13
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Bell CL, Murray SA. Adrenocortical Gap Junctions and Their Functions. Front Endocrinol (Lausanne) 2016; 7:82. [PMID: 27445985 PMCID: PMC4925680 DOI: 10.3389/fendo.2016.00082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/20/2016] [Indexed: 12/21/2022] Open
Abstract
Adrenal cortical steroidogenesis and proliferation are thought to be modulated by gap junction-mediated direct cell-cell communication of regulatory molecules between cells. Such communication is regulated by the number of gap junction channels between contacting cells, the rate at which information flows between these channels, and the rate of channel turnover. Knowledge of the factors regulating gap junction-mediated communication and the turnover process are critical to an understanding of adrenal cortical cell functions, including development, hormonal response to adrenocorticotropin, and neoplastic dedifferentiation. Here, we review what is known about gap junctions in the adrenal gland, with particular attention to their role in adrenocortical cell steroidogenesis and proliferation. Information and insight gained from electrophysiological, molecular biological, and imaging (immunocytochemical, freeze fracture, transmission electron microscopic, and live cell) techniques will be provided.
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Affiliation(s)
- Cheryl L. Bell
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sandra A. Murray
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- *Correspondence: Sandra A. Murray,
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14
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Fang WL, Lai SY, Lai WA, Lee MT, Liao CF, Ke FC, Hwang JJ. CRTC2 and Nedd4 ligase involvement in FSH and TGFβ1 upregulation of connexin43 gap junction. J Mol Endocrinol 2015; 55:263-75. [PMID: 26508620 DOI: 10.1530/jme-15-0076] [Citation(s) in RCA: 9] [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] [Indexed: 12/14/2022]
Abstract
The major mission of the ovarian follicle is the timely production of the mature fertilizable oocyte, and this is achieved by gonadotropin-regulated, gap junction-mediated cell-cell communication between the oocyte and surrounding nurturing granulosa cells. We have demonstrated that FSH and transforming growth factor beta 1 (TGFβ1) stimulate Gja1 gene-encoded connexin43 (Cx43) gap junction formation/function in rat ovarian granulosa cells is important for their induction of steroidogenesis; additionally, cAMP-protein kinase A (PKA)- and calcium-calcineurin-sensitive cAMP response element-binding (CREB) coactivator CRTC2 plays a crucial role during steroidogenesis. This study was to explore the potential molecular mechanism whereby FSH and TGFβ1 regulate Cx43 synthesis and degradation, particularly the involvement of CRTC2 and ubiquitin ligase Nedd4. Primary culture of granulosa cells from ovarian antral follicles of gonadotropin-primed immature rats was used. At 48 h post-treatment, FSH plus TGFβ1 increased Cx43 level and gap junction function in a PKA- and calcineurin-dependent manner, and TGFβ1 acting through its type I receptor modulated FSH action. Chromatin-immunoprecipitation analysis reveals FSH induced an early-phase (45 min) and FSH+TGFβ1 further elicited a late-phase (24 h) increase in CRTC2, CREB and CBP binding to the Gja1 promoter. Additionally, FSH+TGFβ1 increased the half-life of hyper-phosphorylated Cx43 (Cx43-P2). Also, the proteasome inhibitor MG132 prevented the brefeldin A (blocker of protein transport through Golgi)-reduced Cx43-P2 level and membrane Cx43 gap junction plaque. This is associated with FSH+TGFβ1-attenuated Cx43 interaction with Nedd4 and Cx43 ubiquitination. In all, this study uncovers that FSH and TGFβ1 upregulation of Cx43 gap junctions in ovarian granulosa cells critically involves enhancing CRTC2/CREB/CBP-mediated Cx43 expression and attenuating ubiquitin ligase Nedd4-mediated proteosomal degradation of Cx43 protein.
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Affiliation(s)
- Wei-Ling Fang
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
| | - Si-Yi Lai
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
| | - Wei-An Lai
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
| | - Ming-Ting Lee
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
| | - Ching-Fong Liao
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
| | - Ferng-Chun Ke
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
| | - Jiuan-Jiuan Hwang
- School of MedicineInstitute of Physiology, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 112, TaiwanDepartment of NursingHsin-Sheng College of Medical Care and Management, Taoyuan, TaiwanInstitute of Biological ChemistryInstitute of Cellular and Organismic BiologyAcademia Sinica, Taipei, TaiwanCollege of Life ScienceInstitute of Molecular and Cellular Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
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15
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El-Hayek S, Clarke HJ. Follicle-Stimulating Hormone Increases Gap Junctional Communication Between Somatic and Germ-Line Follicular Compartments During Murine Oogenesis. Biol Reprod 2015; 93:47. [PMID: 26063870 DOI: 10.1095/biolreprod.115.129569] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/01/2015] [Indexed: 01/30/2023] Open
Abstract
Germ cells develop in intimate contact and communication with somatic cells of the gonad. In female mammals, oocyte development depends crucially on gap junctions that couple it to the surrounding somatic granulosa cells of the follicle, yet the mechanisms that regulate this essential intercellular communication remain incompletely understood. Follicle-stimulating hormone (FSH) drives the terminal stage of follicular development. We found that FSH increases the steady-state levels of mRNAs encoding the principal connexins that constitute gap junctions and cadherins that mediate cell attachment. This increase occurs both in granulosa cells, which express the FSH-receptor, and in oocytes, which do not. FSH also increased the number of transzonal projections that provide the sites of granulosa cell-oocyte contact. Consistent with increased connexin expression, FSH increased gap junctional communication between granulosa cells and between the oocyte and granulosa cells, and it accelerated oocyte development. These results demonstrate that FSH regulates communication between the female germ cell and its somatic microenvironment. We propose that FSH-regulated gap junctional communication ensures that differentiation processes occurring in distinct cellular compartments within the follicle are precisely coordinated to ensure production of a fertilizable egg.
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Affiliation(s)
- Stephany El-Hayek
- Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada Department of Biology, McGill University, Montreal, Quebec, Canada Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Hugh J Clarke
- Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada Department of Biology, McGill University, Montreal, Quebec, Canada Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
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16
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Ampey BC, Morschauser TJ, Lampe PD, Magness RR. Gap junction regulation of vascular tone: implications of modulatory intercellular communication during gestation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 814:117-32. [PMID: 25015806 DOI: 10.1007/978-1-4939-1031-1_11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In the vasculature, gap junctions (GJ) play a multifaceted role by serving as direct conduits for cell-cell intercellular communication via the facilitated diffusion of signaling molecules. GJs are essential for the control of gene expression and coordinated vascular development in addition to vascular function. The coupling of endothelial cells to each other, as well as with vascular smooth muscle cells via GJs, plays a relevant role in the control of vasomotor tone, tissue perfusion and arterial blood pressure. The regulation of cell-signaling is paramount to cardiovascular adaptations of pregnancy. Pregnancy requires highly developed cell-to-cell coupling, which is affected partly through the formation of intercellular GJs by Cx43, a gap junction protein, within adjacent cell membranes to help facilitate the increase of uterine blood flow (UBF) in order to ensure adequate perfusion for nutrient and oxygen delivery to the placenta and thus the fetus. One mode of communication that plays a critical role in regulating Cx43 is the release of endothelial-derived vasodilators such as prostacyclin (PGI2) and nitric oxide (NO) and their respective signaling mechanisms involving second messengers (cAMP and cGMP, respectively) that are likely to be important in maintaining UBF. Therefore, the assertion we present in this review is that GJs play an integral if not a central role in maintaining UBF by controlling rises in vasodilators (PGI2 and NO) via cyclic nucleotides. In this review, we discuss: (1) GJ structure and regulation; (2) second messenger regulation of GJ phosphorylation and formation; (3) pregnancy-induced changes in cell-signaling; and (4) the role of uterine arterial endothelial GJs during gestation. These topics integrate the current knowledge of this scientific field with interpretations and hypotheses regarding the vascular effects that are mediated by GJs and their relationship with vasodilatory vascular adaptations required for modulating the dramatic physiological rises in uteroplacental perfusion and blood flow observed during normal pregnancy.
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Affiliation(s)
- Bryan C Ampey
- Perinatal Research Laboratories, Department of Obstetrics & Gynecology, School Medicine and Public Health, University of Wisconsin - Madison, Madison, WI, 53715, USA
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17
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Pidoux G, Gerbaud P, Dompierre J, Lygren B, Solstad T, Evain-Brion D, Taskén K. A PKA-ezrin-Cx43 signaling complex controls gap junction communication and thereby trophoblast cell fusion. J Cell Sci 2014; 127:4172-85. [PMID: 25052094 DOI: 10.1242/jcs.149609] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cell fusion occurs as part of the differentiation of some cell types, including myotubes in muscle and osteoclasts in remodeling bone. In the human placenta, mononuclear cytotrophoblasts in a human chorionic gonadotropin (hCG)-driven process fuse to form multinucleated syncytia that allow the exchange of nutrients and gases between the maternal and fetal circulation. Experiments in which protein kinase A (PKA) is displaced from A-kinase anchoring proteins (AKAPs), or in which specific AKAPs are depleted by siRNA-mediated knockdown, point to ezrin as a scaffold required for hCG-, cAMP- and PKA-mediated regulation of the fusion process. By a variety of immunoprecipitation and immunolocalization experiments, we show that ezrin directs PKA to a molecular complex of connexin 43 (Cx43, also known as GJA1) and zona occludens-1 (ZO-1, also known as TJP1). A combination of knockdown experiments and reconstitution with ezrin or Cx43 with or without the ability to bind to its interaction partner or to PKA demonstrate that ezrin-mediated coordination of the localization of PKA and Cx43 is necessary for discrete control of Cx43 phosphorylation and hCG-stimulated gap junction communication that triggers cell fusion in cytotrophoblasts.
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Affiliation(s)
- Guillaume Pidoux
- INSERM, U767, Paris, F-75006 France Université Paris Descartes, Paris F-75006, France PremUp, Paris, F-75006 France Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo N-0318, Norway Biotechnology Centre, University of Oslo, Oslo N-0317, Norway
| | - Pascale Gerbaud
- INSERM, U767, Paris, F-75006 France Université Paris Descartes, Paris F-75006, France
| | - Jim Dompierre
- CNRS, FRC3115, Centre de Recherche de Gif, IMAGIF, Plateforme de Microscopie Photonique, Gif-sur-Yvette, F-91198, France
| | - Birgitte Lygren
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo N-0318, Norway Biotechnology Centre, University of Oslo, Oslo N-0317, Norway
| | - Therese Solstad
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo N-0318, Norway Biotechnology Centre, University of Oslo, Oslo N-0317, Norway
| | - Danièle Evain-Brion
- INSERM, U767, Paris, F-75006 France Université Paris Descartes, Paris F-75006, France PremUp, Paris, F-75006 France
| | - Kjetil Taskén
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo N-0318, Norway Biotechnology Centre, University of Oslo, Oslo N-0317, Norway K.G. Jebsen Inflammation Research Centre, University of Oslo, Oslo N-0317, Norway K.G. Jebsen Centre for Cancer Immunotherapy, University of Oslo, Oslo N-0317, Norway Department of Infectious Diseases, Oslo University Hospital, N-0407 Oslo, Norway
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18
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Batra N, Riquelme MA, Burra S, Kar R, Gu S, Jiang JX. Direct regulation of osteocytic connexin 43 hemichannels through AKT kinase activated by mechanical stimulation. J Biol Chem 2014; 289:10582-10591. [PMID: 24563481 DOI: 10.1074/jbc.m114.550608] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Connexin (Cx) 43 hemichannels in osteocytes are thought to play a critical role in releasing bone modulators in response to mechanical loading, a process important for bone formation and remodeling. However, the underlying mechanism that regulates the opening of mechanosensitive hemichannels is largely unknown. We have recently shown that Cx43 and integrin α5 interact directly with each other, and activation of PI3K appears to be required for Cx43 hemichannel opening by mechanical stimulation. Here, we show that mechanical loading through fluid flow shear stress (FFSS) increased the level of active AKT, a downstream effector of PI3K, which is correlated with the opening of hemichannels. Both Cx43 and integrin α5 are directly phosphorylated by AKT. Inhibition of AKT activation significantly reduced FFSS-induced opening of hemichannels and disrupted the interaction between Cx43 and integrin α5. Moreover, AKT phosphorylation on Cx43 and integrin α5 enhanced their interaction. In contrast to the C terminus of wild-type Cx43, overexpression of the C-terminal mutant containing S373A, a consensus site previously shown to be phosphorylated by AKT, failed to bind with α5 and hence could not inhibit hemichannel opening. Together, our results suggest that AKT activated by FFSS directly phosphorylates Cx43 and integrin α5, and Ser-373 of Cx43 plays a predominant role in mediating the interaction between these two proteins and Cx43 hemichannel opening, a crucial step to mediate the anabolic function of mechanical loading in the bone.
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Affiliation(s)
- Nidhi Batra
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - Manuel A Riquelme
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - Sirisha Burra
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - Rekha Kar
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - Sumin Gu
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - Jean X Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900.
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19
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Sugimura S, Ritter LJ, Sutton-McDowall ML, Mottershead DG, Thompson JG, Gilchrist RB. Amphiregulin co-operates with bone morphogenetic protein 15 to increase bovine oocyte developmental competence: effects on gap junction-mediated metabolite supply. ACTA ACUST UNITED AC 2014; 20:499-513. [DOI: 10.1093/molehr/gau013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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20
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Navalakhe RM, Jagtap DD, Nayak SU, Nandedkar TD, Mahale SD. Effect of FSH receptor-binding inhibitor-8 on FSH-mediated granulosa cell signaling and proliferation. Chem Biol Drug Des 2014; 82:178-88. [PMID: 23601330 DOI: 10.1111/cbdd.12149] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 02/26/2013] [Accepted: 04/15/2013] [Indexed: 11/29/2022]
Abstract
Follicle-stimulating hormone is important for mammalian reproduction. It acts through specific receptors located on the plasma membrane of granulosa cells in ovaries and Sertoli cells in testes. The binding of follicle-stimulating hormone to its receptor activates intracytoplasmic signaling pathways leading to steroidogenesis. These steroids in turn regulate the follicle-stimulating hormone action from the anterior pituitary through exerting negative feedback effect. In addition to steroids, non-steroidal factors secreted by the ovaries are believed to modulate follicle-stimulating hormone action through autocrine/paracrine mode. One such low molecular weight peptide referred to as follicle-stimulating hormone receptor-binding inhibitor-8 purified from human follicular fluid has been extensively studied. Follicle-stimulating hormone receptor-binding inhibitor-8 has been shown to inhibit binding of follicle-stimulating hormone to its receptor. The present article describes the effect of follicle-stimulating hormone receptor-binding inhibitor-8 on follicle-stimulating hormone-induced signaling in rat granulosa cells. Follicle-stimulating hormone receptor-binding inhibitor-8 inhibited the follicle-stimulating hormone-induced cAMP, and the effect was observed to be mediated through the protein kinase A. Further, an inhibitory effect of follicle-stimulating hormone receptor-binding inhibitor-8 on the granulosa cell proliferation was evaluated using COV434 cell line which is derived from the human granulosa cell tumor. The effect of the peptide on the cell cycle analysis showed an increase in apoptotic population and the arrest of G1 phase. These findings suggest that follicle-stimulating hormone receptor-binding inhibitor-8 acts as a follicle-stimulating hormone antagonist and affects the follicle-stimulating hormone-mediated signaling and proliferation in the granulosa cells.
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Affiliation(s)
- Rajshri M Navalakhe
- Division of Structural Biology, National Institute for Research in Reproductive Health NIRRH, Indian Council of Medical Research, Jehangir Merwanji Street, Parel, Mumbai, 400012, India
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21
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Nielsen MS, Axelsen LN, Sorgen PL, Verma V, Delmar M, Holstein-Rathlou NH. Gap junctions. Compr Physiol 2013; 2:1981-2035. [PMID: 23723031 DOI: 10.1002/cphy.c110051] [Citation(s) in RCA: 289] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease.
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Affiliation(s)
- Morten Schak Nielsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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22
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Dunn CA, Lampe PD. Injury-triggered Akt phosphorylation of Cx43: a ZO-1-driven molecular switch that regulates gap junction size. J Cell Sci 2013; 127:455-64. [PMID: 24213533 DOI: 10.1242/jcs.142497] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The proteins that form vertebrate gap junctions, the connexins, are highly regulated and have short (<2 hour) half-lives. Phosphorylation of connexin43 (Cx43) affects gap junction assembly, channel gating and turnover. After finding dramatic effects on gap junctions with Akt inhibitors, we created an antibody specific for Cx43 phosphorylated on S373, a potential Akt substrate. We found S373 phosphorylation in cells and skin or heart almost exclusively in larger gap-junctional structures that increased dramatically after wounding or hypoxia. We were able to mechanistically show that Akt-dependent phosphorylation of S373 increases gap junction size and communication by completely eliminating the interaction between Cx43 and ZO-1. Thus, phosphorylation on S373 acts as a molecular 'switch' to rapidly increase gap-junctional communication, potentially leading to initiation of activation and migration of keratinocytes or ischemic injury response in the skin and the heart, respectively.
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Affiliation(s)
- Clarence A Dunn
- Translational Research Program, Human Biology and Public Health Sciences Divisions, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA
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23
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Axelsen LN, Calloe K, Holstein-Rathlou NH, Nielsen MS. Managing the complexity of communication: regulation of gap junctions by post-translational modification. Front Pharmacol 2013; 4:130. [PMID: 24155720 PMCID: PMC3804956 DOI: 10.3389/fphar.2013.00130] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 09/30/2013] [Indexed: 12/21/2022] Open
Abstract
Gap junctions are comprised of connexins that form cell-to-cell channels which couple neighboring cells to accommodate the exchange of information. The need for communication does, however, change over time and therefore must be tightly controlled. Although the regulation of connexin protein expression by transcription and translation is of great importance, the trafficking, channel activity and degradation are also under tight control. The function of connexins can be regulated by several post translational modifications, which affect numerous parameters; including number of channels, open probability, single channel conductance or selectivity. The most extensively investigated post translational modifications are phosphorylations, which have been documented in all mammalian connexins. Besides phosphorylations, some connexins are known to be ubiquitinated, SUMOylated, nitrosylated, hydroxylated, acetylated, methylated, and γ-carboxyglutamated. The aim of the present review is to summarize our current knowledge of post translational regulation of the connexin family of proteins.
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Affiliation(s)
- Lene N Axelsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health and Medical Sciences, University of Copenhagen Copenhagen, Denmark
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24
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Santiquet NW, Develle Y, Laroche A, Robert C, Richard FJ. Regulation of gap-junctional communication between cumulus cells during in vitro maturation in swine, a gap-FRAP study. Biol Reprod 2012; 87:46. [PMID: 22649071 DOI: 10.1095/biolreprod.112.099754] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Intercellular gap-junctional communication (GJC) plays an important role in ovarian cell physiology. Closure of GJC has been proposed to be involved in oocyte maturation, particularly in the resumption of meiosis, both in vivo and in vitro, by controlling the flow of meiosis inhibitors, such as cAMP and cGMP. Understanding how GJC dynamics are regulated during in vitro maturation (IVM) could provide a powerful tool for controlling meiotic resumption and oocyte maturation in vitro. Since little is known about the GJC dynamic regulation between cumulus cells, we have developed an assay based on recovery of calcein fluorescence in photobleached cumulus cells, a gap-FRAP assay. The GJC profile has been characterized during the first hours of porcine IVM. We showed that equine chorionic gonadotropin (eCG) and epidermal growth factor (EGF) down-regulated GJC effectiveness between cumulus cells. However, human chorionic gonadotropin was not down-regulating GJC effectiveness. We also showed that the GJC network expanded during this period and that this effect was not regulated by gonadotropins. Porcine follicular fluid present in the maturation medium also had an impact on GJC regulation, increasing GJC network establishment and the effectiveness of calcein transfer rate between cumulus cells. These results show that both eCG and EGF are regulating the decrease in GJC effectiveness after 4.5 h of IVM, while the network extension is gonadotropin independent. Regulation of GJC between cumulus cells would then be specifically regulated during in vitro IVM.
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Affiliation(s)
- Nicolas W Santiquet
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, FSAA, Université Laval, Québec, Québec, Canada
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25
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Knapczyk-Stwora K, Durlej-Grzesiak M, Duda M, Slomczynska M. Expression of Connexin 43 in the Porcine Foetal Gonads During Development. Reprod Domest Anim 2012; 48:272-7. [DOI: 10.1111/j.1439-0531.2012.02144.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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26
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Gilleron J, Carette D, Chevallier D, Segretain D, Pointis G. Molecular connexin partner remodeling orchestrates connexin traffic: from physiology to pathophysiology. Crit Rev Biochem Mol Biol 2012; 47:407-23. [PMID: 22551357 DOI: 10.3109/10409238.2012.683482] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Connexins, through gap junctional intercellular communication, are known to regulate many physiological functions involved in developmental processes such as cell proliferation, differentiation, migration and apoptosis. Strikingly, alterations of connexin expression and trafficking are often, if not always, associated with human developmental diseases and carcinogenesis. In this respect, disrupted trafficking dynamics and aberrant intracytoplasmic localization of connexins are considered as typical features of functionality failure leading to the pathological state. Recent findings demonstrate that interactions of connexins with numerous protein partners, which take place throughout connexin trafficking, are essential for gap junction formation, membranous stabilization and degradation. In the present study, we give an overview of the physiological molecular machinery and of the specific interactions between connexins and their partners, which are involved in connexin trafficking, and we highlight their changes in pathological situations.
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Affiliation(s)
- Jérôme Gilleron
- INSERM U 1065, University Nice Sophia Antipolis, Team 5, C3M, 151 route Saint-Antoine de Ginestière, France
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27
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Dunk CE, Gellhaus A, Drewlo S, Baczyk D, Pötgens AJG, Winterhager E, Kingdom JCP, Lye SJ. The molecular role of connexin 43 in human trophoblast cell fusion. Biol Reprod 2012; 86:115. [PMID: 22238282 DOI: 10.1095/biolreprod.111.096925] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Connexin expression and gap junctional intercellular communication (GJIC) mediated by connexin 43 (Cx43)/gap junction A1 (GJA1) are required for cytotrophoblast fusion into the syncytium, the outer functional layer of the human placenta. Cx43 also impacts intracellular signaling through protein-protein interactions. The transcription factor GCM1 and its downstream target ERVW-1/SYNCYTIN-1 are key players in trophoblast fusion and exert their actions through the ERVW-1 receptor SLC1A5/ASCT-2/RDR/ATB(0). To investigate the molecular role of the Cx43 protein and its interaction with this fusogenic pathway, we utilized stable Cx43-transfected cell lines established from the choriocarcinoma cell line Jeg3: wild-type Jeg3, alphahCG/Cx43 (constitutive Cx43 expression), JpUHD/Cx43 (doxycyclin-inducible Cx43 expression), or JpUHD/trCx43 (doxycyclin-inducible Cx43 carboxyterminal deleted). We hypothesized that truncation of Cx43 at its C-terminus would inhibit trophoblast fusion and protein interaction with either ERVW-1 or SLC1A5. In the alphahCG/Cx43 and JpUHD/Cx43 lines, stimulation with cAMP caused 1) increase in GJA1 mRNA levels, 2) increase in percentage of fused cells, and 3) downregulation of SLC1A5 expression. Cell fusion was inhibited by GJIC blockade using carbenoxylone. Neither Jeg3, which express low levels of Cx43, nor the JpUHD/trCx43 cell line demonstrated cell fusion or downregulation of SLC1A5. However, GCM1 and ERVW-1 mRNAs were upregulated by cAMP treatment in both Jeg3 and all Cx43 cell lines. Silencing of GCM1 prevented the induction of GJA1 mRNA by forskolin in BeWo choriocarcinoma cells, demonstrating that GCM1 is upstream of Cx43. All cell lines and first-trimester villous explants also demonstrated coimmunoprecipitation of SLC1A5 and phosphorylated Cx43. Importantly, SLC1A5 and Cx43 gap junction plaques colocalized in situ to areas of fusing cytotrophoblast, as demonstrated by the loss of E-cadherin staining in the plasma membrane in first-trimester placenta. We conclude that Cx43-mediated GJIC and SLC1A5 interaction play important functional roles in trophoblast cell fusion.
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Affiliation(s)
- Caroline E Dunk
- Research Centre for Women's and Infants' Health, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.
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28
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Palatinus JA, Rhett JM, Gourdie RG. The connexin43 carboxyl terminus and cardiac gap junction organization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1831-43. [PMID: 21856279 DOI: 10.1016/j.bbamem.2011.08.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Revised: 07/25/2011] [Accepted: 08/03/2011] [Indexed: 12/09/2022]
Abstract
The precise spatial order of gap junctions at intercalated disks in adult ventricular myocardium is thought vital for maintaining cardiac synchrony. Breakdown or remodeling of this order is a hallmark of arrhythmic disease of the heart. The principal component of gap junction channels between ventricular cardiomyocytes is connexin43 (Cx43). Protein-protein interactions and modifications of the carboxyl-terminus of Cx43 are key determinants of gap junction function, size, distribution and organization during normal development and in disease processes. Here, we review data on the role of proteins interacting with the Cx43 carboxyl-terminus in the regulation of cardiac gap junction organization, with particular emphasis on Zonula Occludens-1. The rapid progress in this area suggests that in coming years we are likely to develop a fuller understanding of the molecular mechanisms causing pathologic remodeling of gap junctions. With these advances come the promise of novel approach to the treatment of arrhythmia and the prevention of sudden cardiac death. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- Joseph A Palatinus
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
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Wang Z, Do CW, Valiunas V, Leung CT, Cheng AKW, Clark AF, Wax MB, Chatterton JE, Civan MM. Regulation of gap junction coupling in bovine ciliary epithelium. Am J Physiol Cell Physiol 2010; 298:C798-806. [PMID: 20089928 PMCID: PMC2853215 DOI: 10.1152/ajpcell.00406.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 01/20/2010] [Indexed: 12/11/2022]
Abstract
Aqueous humor is formed by fluid transfer from the ciliary stroma sequentially across the pigmented ciliary epithelial (PE) cells, gap junctions, and nonpigmented ciliary epithelial (NPE) cells. Which connexins (Cx) contribute to PE-NPE gap junctional formation appears species specific. We tested whether small interfering RNA (siRNA) against Cx43 (siCx43) affects bovine PE-NPE communication and whether cAMP affects communication. Native bovine ciliary epithelial cells were studied by dual-cell patch clamping, Lucifer Yellow (LY) transfer, quantitative polymerase chain reaction with reverse transcription (qRT-PCR), and Western immunoblot. qRT-PCR revealed at least 100-fold greater expression for Cx43 than Cx40. siCx43 knocked down target mRNA expression by 55 +/- 7% after 24 h, compared with nontargeting control siRNA (NTC1) transfection. After 48 h, siCx43 reduced Cx43 protein expression and LY transfer. The ratio of fluorescence intensity (R(f)) in recipient to donor cell was 0.47 +/- 0.09 (n = 11) 10 min after whole cell patch formation in couplets transfected with NTC1. siCx43 decreased R(f) by approximately 60% to 0.20 +/- 0.07 (n = 13, P < 0.02). Dibutyryl-cAMP (500 microM) also reduced LY dye transfer by approximately 60%, reducing R(f) from 0.41 +/- 0.05 (n = 15) to 0.17 +/- 0.05 (n = 20) after 10 min. Junctional currents were lowered by approximately 50% (n = 6) after 10-min perfusion with 500 microM dibutyryl-cAMP (n = 6); thereafter, heptanol abolished the currents (n = 5). Preincubation with the PKA inhibitor H-89 (2 microM) prevented cAMP-triggered current reduction (n = 6). We conclude that 1) Cx43, but not Cx40, is a major functional component of bovine PE-NPE gap junctions; and 2) under certain conditions, cAMP may act through PKA to inhibit bovine PE-NPE gap junctional communication.
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Affiliation(s)
- Zhao Wang
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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30
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Abstract
Vertebrate gap junctions, composed of proteins from the connexin gene family, play critical roles in embryonic development, co-ordinated contraction of excitable cells, tissue homoeostasis, normal cell growth and differentiation. Phosphorylation of connexin43, the most abundant and ubiquitously expressed connexin, has been implicated in the regulation of gap junctional communication at several stages of the connexin 'life cycle', including hemichannel oligomerization, export of the protein to the plasma membrane, hemichannel activity, gap junction assembly, gap junction channel gating and connexin degradation. Consistent with a short (1-5 h) protein half-life, connexin43 phosphorylation is dynamic and changes in response to activation of many different kinases. The present review assesses our current understanding of the effects of phosphorylation on connexin43 structure and function that in turn regulate gap junction biology, with an emphasis on events occurring in heart and skin.
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Sasseville' M, Gagnon MC, Guillemette C, Sullivan R, Gilchrist RB, Richard FJ. Regulation of gap junctions in porcine cumulus-oocyte complexes: contributions of granulosa cell contact, gonadotropins, and lipid rafts. Mol Endocrinol 2009; 23:700-10. [PMID: 19228792 DOI: 10.1210/me.2008-0320] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Gap-junctional communication (GJC) plays a central role in oocyte growth. However, little is known about the regulation of connexin 43 (Cx43)-based gap-junction channels in cumulus-oocyte complexes (COCs) during in vitro maturation. We show that rupture of COCs from mural granulosa cells up-regulates Cx43-mediated GJC and that gonadotropins signal GJC breakdown by recruiting Cx43 to lipid rafts when oocyte meiosis resumes. Oocyte calcein uptake through gap junctions increases during early in vitro oocyte maturation and remains high until 18 h, when it falls simultaneously with the oocyte germinal vesicle breakdown. Immunodetection of Cx43 and fluorescence recovery after photobleaching assays revealed that the increase of GJC is independent of gonadotropins but requires RNA transcription, RNA polyadenylation, and translation. GJC rupture, in contrast, is achieved by a gonadotropin-dependent mechanism involving recruitment of Cx43 to clustered lipid rafts. These results show that GJC up-regulation in COCs in in vitro culture is independent of gonadotropins and transcriptionally regulated. However, GJC breakdown is gonadotropin dependent and mediated by the clustering of Cx43 in lipid raft microdomains. In conclusion, this study supports a functional role of lipid raft clustering of Cx43 in GJC breakdown in the COCs during in vitro maturation.
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Affiliation(s)
- Maxime Sasseville'
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Canada
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Vaccari S, Horner K, Mehlmann LM, Conti M. Generation of mouse oocytes defective in cAMP synthesis and degradation: endogenous cyclic AMP is essential for meiotic arrest. Dev Biol 2008; 316:124-34. [PMID: 18280465 PMCID: PMC2755085 DOI: 10.1016/j.ydbio.2008.01.018] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 01/11/2008] [Accepted: 01/11/2008] [Indexed: 11/21/2022]
Abstract
Although it is established that cAMP accumulation plays a pivotal role in preventing meiotic resumption in mammalian oocytes, the mechanisms controlling cAMP levels in the female gamete have remained elusive. Both production of cAMP via GPCRs/Gs/adenylyl cyclases endogenous to the oocyte as well as diffusion from the somatic compartment through gap junctions have been implicated in maintaining cAMP at levels that preclude maturation. Here we have used a genetic approach to investigate the different biochemical pathways contributing to cAMP accumulation and maturation in mouse oocytes. Because cAMP hydrolysis is greatly decreased and cAMP accumulates above a threshold, oocytes deficient in PDE3A do not resume meiosis in vitro or in vivo, resulting in complete female infertility. In vitro, inactivation of Gs or downregulation of the GPCR GPR3 causes meiotic resumption in the Pde3a null oocytes. Crossing of Pde3a(-/-) mice with Gpr3(-/-) mice causes partial recovery of female fertility. Unlike the complete meiotic block of the Pde3a null mice, oocyte maturation is restored in the double knockout, although it occurs prematurely as described for the Gpr3(-/-) mouse. The increase in cAMP that follows PDE3A ablation is not detected in double mutant oocytes, confirming that GPR3 functions upstream of PDE3A in the regulation of oocyte cAMP. Metabolic coupling between oocytes and granulosa cells was not affected in follicles from the single or double mutant mice, suggesting that diffusion of cAMP is not prevented. Finally, simultaneous ablation of GPR12, an additional receptor expressed in the oocyte, does not modify the Gpr3(-/-) phenotype. Taken together, these findings demonstrate that Gpr3 is epistatic to Pde3a and that fertility as well as meiotic arrest in the PDE3A-deficient oocyte is dependent on the activity of GPR3. These findings also suggest that cAMP diffusion through gap junctions or the activity of additional receptors is not sufficient by itself to maintain the meiotic arrest in the mouse oocyte.
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Affiliation(s)
- Sergio Vaccari
- Division of Reproductive Biology, Department of Obstetrics and Gynecology Stanford University 94305
| | - Kathleen Horner
- Division of Reproductive Biology, Department of Obstetrics and Gynecology Stanford University 94305
| | - Lisa M. Mehlmann
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032
| | - Marco Conti
- Division of Reproductive Biology, Department of Obstetrics and Gynecology Stanford University 94305
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Park DJ, Wallick CJ, Martyn KD, Lau AF, Jin C, Warn-Cramer BJ. Akt phosphorylates Connexin43 on Ser373, a "mode-1" binding site for 14-3-3. ACTA ACUST UNITED AC 2008; 14:211-26. [PMID: 18163231 DOI: 10.1080/15419060701755958] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Connexin43 (Cx43) is a membrane-spanning protein that forms channels that bridge the gap between adjacent cells and this allows for the intercellular exchange of information. Cx43 is regulated by phosphorylation and by interacting proteins. "Mode-1" interaction with 14-3-3 requires phosphorylation of Ser373 on Cx43 (Park et al. 2006). Akt phosphorylates and targets a number of proteins to interactions with 14-3-3. Here we demonstrate that Akt phosphorylates Cx43 on Ser373 and Ser369; antibodies recognizing Akt-phosphorylated sites or phospho-Ser "mode-1" 14-3-3-binding sites recognize a protein from EGF-treated cells that migrates as Cx43, and GST-14-3-3 binds to Cx43 phosphorylated endogenously in EGF-treated cells. Confocal microscopy supports the co-localization of Cx43 with Akt and with 14-3-3 at the outer edges of gap junctional plaques. These data suggest that Akt could target Cx43 to an interaction with 14-3-3 that may play a role in the forward trafficking of Cx43 multimers and/or their incorporation into existing gap junctional plaques.
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Affiliation(s)
- Darren J Park
- Natural Products & Cancer Biology Program, Cancer Research Center, University of Hawaii at Manoa, Honolulu, Hawaii 96813, USA
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Abstract
Gap junctions that allow the direct communication between cytoplasmic compartments of neighboring cells are present in a variety of tissues and organs and play pivotal roles in a wide range of physiological processes. In the ovary, gap junctions consist mainly of connexin (Cx) 43 and Cx37, and their indispensable role in regulating folliculogenesis and oogenesis is well established. The ovarian Cx43 is regulated by gonadotropins at the transcriptional, translational and post-translational levels whereas the regulation of the ovarian Cx37 is yet unknown. In addition to their involvement in normal ovarian functions, gap junction proteins, particularly Cx43, seem to act as cancer suppressors. A summary of our present knowledge regarding gap junctional communication (GJC) and the ovarian gap junction proteins in normally developing ovaries and under pathological conditions is presented in this review.
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Affiliation(s)
- Eran Gershon
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
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Solan JL, Marquez-Rosado L, Sorgen PL, Thornton PJ, Gafken PR, Lampe PD. Phosphorylation at S365 is a gatekeeper event that changes the structure of Cx43 and prevents down-regulation by PKC. ACTA ACUST UNITED AC 2008; 179:1301-9. [PMID: 18086922 PMCID: PMC2140020 DOI: 10.1083/jcb.200707060] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphorylation at unspecified sites is known to regulate the life cycle (assembly, gating, and turnover) of the gap junction protein, Cx43. In this paper, we show that Cx43 is phosphorylated on S365 in cultured cells and heart tissue. Nuclear magnetic resonance structural studies of the C-terminal region of Cx43 with an S365D mutation indicate that it forms a different stable conformation than unphosphorylated wild-type Cx43. Immunolabeling with an antibody specific for Cx43 phosphorylated at S365 shows staining on gap junction structures in heart tissue that is lost upon hypoxia when Cx43 is no longer specifically localized to the intercalated disk. Efficient phosphorylation at S368, an important Cx43 channel regulatory event that increases during ischemia or PKC activation, depends on S365 being unphosphorylated. Thus, phosphorylation at S365 can serve a “gatekeeper” function that may represent a mechanism to protect cells from ischemia and phorbol ester-induced down-regulation of channel conductance.
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Affiliation(s)
- Joell L Solan
- Molecular Diagnostics Program and 2Proteomics Shared Resource, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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36
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Sosinsky GE, Solan JL, Gaietta GM, Ngan L, Lee GJ, Mackey MR, Lampe PD. The C-terminus of connexin43 adopts different conformations in the Golgi and gap junction as detected with structure-specific antibodies. Biochem J 2007; 408:375-85. [PMID: 17714073 PMCID: PMC2267357 DOI: 10.1042/bj20070550] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 08/13/2007] [Accepted: 08/23/2007] [Indexed: 11/17/2022]
Abstract
The C-terminus of the most abundant and best-studied gap-junction protein, connexin43, contains multiple phosphorylation sites and protein-binding domains that are involved in regulation of connexin trafficking and channel gating. It is well-documented that SDS/PAGE of NRK (normal rat kidney) cell lysates reveals at least three connexin43-specific bands (P0, P1 and P2). P1 and P2 are phosphorylated on multiple, unidentified serine residues and are found primarily in gap-junction plaques. In the present study we prepared monoclonal antibodies against a peptide representing the last 23 residues at the C-terminus of connexin43. Immunofluorescence studies showed that one antibody (designated CT1) bound primarily to connexin43 present in the Golgi apparatus, whereas the other antibody (designated IF1) labelled predominately connexin43 present in gap junctions. CT1 immunoprecipitates predominantly the P0 form whereas IF1 recognized all three bands. Peptide mapping, mutational analysis and protein-protein interaction experiments revealed that unphosphorylated Ser364 and/or Ser365 are critical for CT1 binding. The IF1 paratope binds to residues Pro375-Asp379 and requires Pro375 and Pro377. These proline residues are also necessary for ZO-1 interaction. These studies indicate that the conformation of Ser364/Ser365 is important for intracellular localization, whereas the tertiary structure of Pro375-Asp379 is essential in targeting and regulation of gap junctional connexin43.
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Key Words
- confocal microscopy
- connexin
- electron microscopy
- gap junction
- membrane protein structure
- phosphorylation
- trafficking
- bfa, brefeldin a
- cx, connexin
- cy5, indodicarbocyanine
- dapi, 4′,6-diamidino-2-phenylindole
- em, electron microscopy
- gst, glutathione transferase
- mdck, madin–darby canine kidney
- nrk, normal rat kidney
- pkc, protein kinase c
- tgn, trans-golgi network
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Affiliation(s)
- Gina E Sosinsky
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, CA 92093-0608, USA.
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Pahujaa M, Anikin M, Goldberg GS. Phosphorylation of connexin43 induced by Src: regulation of gap junctional communication between transformed cells. Exp Cell Res 2007; 313:4083-90. [PMID: 17956757 DOI: 10.1016/j.yexcr.2007.09.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 09/06/2007] [Accepted: 09/06/2007] [Indexed: 01/14/2023]
Abstract
Cx43 is a widely expressed gap junction protein that mediates communication between many cell types. In general, tumor cells display less intercellular communication than their nontransformed precursors. The Src tyrosine kinase has been implicated in progression of a wide variety of cancers. Src can phosphorylate Cx43, and this event is associated with the suppression of gap junction communication. However, Src activates multiple signaling pathways that can also affect intercellular communication. For example, serine kinases including PKC and MAPK are downstream effectors of Src that can also phosphorylate Cx43 and disrupt gap junctional communication. In addition, Src can affect the expression of other proteins that may affect intercellular communication. Indeed, disruption of gap junctions by Src appears to be complex. It has become clear that Src can affect Cx43 activity by multiple mechanisms. Here, we review how Src may orchestrate events that regulate intercellular communication mediated by Cx43.
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Affiliation(s)
- Madhuri Pahujaa
- Department of Cell Biology, University of Medicine and Dentistry of New Jersey, Science Center, 2 Medical Center Dr., Stratford, NJ 08084, USA
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Wang Z, Shi F, Jiang YQ, Lu LZ, Wang H, Watanabe G, Taya K. Changes of cyclic AMP levels and phosphodiesterase activities in the rat ovary. J Reprod Dev 2007; 53:717-25. [PMID: 17380041 DOI: 10.1262/jrd.18156] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyclic AMP (cAMP) is a second messenger that plays a critical role in follicular recruitment, development and luteinization in the mammalian ovary. The cellular level of cAMP is largely dependent on the activity of phosphodiesterase (PDE), which degrades cAMP into 5'-AMP. The present study was conducted to investigate the level of cAMP and the activity of cAMP-PDE in postnatal rats; immature rats during gonadotropin-primed follicular development, ovulation and luteinization; adult rats during normal estrous cycling; and aged rats that spontaneously developed persistent estrous (PE) by radioimmunoassay (RIA). All four rat models were confirmed by histological examination of one ovary and assayed using the other ovary by RIA. In the postnatal rats, the ovarian cAMP level was high on day 10 after birth, while ovarian cAMP-PDE activity was highest at 21 days of age. In the immature female rats, both the ovarian cAMP level and cAMP-PDE activity increased remarkably after treatment with equine chorionic gonadotropin (eCG), increased continuously 24 h after injection of human chorionic gonadotropin (hCG) for induction of ovulation and luteinization, and then declined significantly. In the adult rats during the normal estrous cycle, the ovarian cAMP levels were low on the day of estrus, and there were no significant changes in ovarian cAMP-PDE activity throughout the estrous cycle. In the PE rats, the ovarian cAMP levels were similar to those of the adult rats on the day of estrus but were lower than those on the other days of the estrous cycle; ovarian cAMP-PDE activity was lower than that in the adult rats on any day of the estrous cycle. Together, these findings indicate that the ovarian cAMP level and cAMP-PDE activity were regulated in a stage-dependent manner during ovarian follicular development, atresia and luteinization and providing evidences that cAMP and cAMP-specific PDEs are involved in these physiological processes.
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Affiliation(s)
- Zhengchao Wang
- Laboratory of Animal Reproduction, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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Amano R, Lee J, Goto N, Harayama H. Evidence for existence of cAMP-Epac signaling in the heads of mouse epididymal spermatozoa. J Reprod Dev 2006; 53:127-33. [PMID: 17077580 DOI: 10.1262/jrd.18077] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyclic adenosine 3',5'-monophosphate (cAMP) signaling regulates the expression of fertilizing ability in mammalian spermatozoa. Many articles indicate that this signaling is mediated mainly via protein kinase A. Recently, a guanine nucleotide exchange factor for small G protein Rap1 (an exchange protein directly activated by cAMP: Epac) was discovered as a new mediator of cAMP signaling in somatic cells. The aim of this study was to reveal the existence of cAMP-Epac signaling in mouse spermatozoa. Northern blot analysis and in situ hybridization suggested that Epac1 and Epac2 mRNAs were transcribed in the seminiferous epithelia of the testis. This shows that expression of Epac mRNAs is present in mouse testicular germ cells. Indirect immunofluorescence with specific polyclonal antibodies suggested possible co-localization of Epac1 and Rap1 proteins in the heads of epididymal spermatozoa. Moreover, treatment of epididymal spermatozoa with an Epac-specific cAMP analog, 8-pMeOPT-2'-O-Me-cAMP, induced activation of Rap1, as revealed with a commercial kit for pull-down assay. These results indicate the existence of cAMP-Epac signaling in the heads of mouse epididymal spermatozoa.
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Affiliation(s)
- Reiko Amano
- Graduate School of Science and Technology, Kobe University, Japan
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