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Delisle BP, Prabhat A, Burgess DE, Ono M, Esser KA, Schroder EA. Circadian Regulation of Cardiac Arrhythmias and Electrophysiology. Circ Res 2024; 134:659-674. [PMID: 38484028 DOI: 10.1161/circresaha.123.323513] [Citation(s) in RCA: 1] [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: 03/19/2024]
Abstract
Circadian rhythms in physiology and behavior are ≈24-hour biological cycles regulated by internal biological clocks (ie, circadian clocks) that optimize organismal homeostasis in response to predictable environmental changes. These clocks are present in virtually all cells in the body, including cardiomyocytes. Many decades ago, clinicians and researchers became interested in studying daily patterns of triggers for sudden cardiac death, the incidence of sudden cardiac death, and cardiac arrhythmias. This review highlights historical and contemporary studies examining the role of day/night rhythms in the timing of cardiovascular events, delves into changes in the timing of these events over the last few decades, and discusses cardiovascular disease-specific differences in the timing of cardiovascular events. The current understanding of the environmental, behavioral, and circadian mechanisms that regulate cardiac electrophysiology is examined with a focus on the circadian regulation of cardiac ion channels and ion channel regulatory genes. Understanding the contribution of environmental, behavioral, and circadian rhythms on arrhythmia susceptibility and the incidence of sudden cardiac death will be essential in developing future chronotherapies.
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Affiliation(s)
- Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington (B.P.D., A.P., D.E.B.)
| | - Abhilash Prabhat
- Department of Physiology, University of Kentucky, Lexington (B.P.D., A.P., D.E.B.)
| | - Don E Burgess
- Department of Physiology, University of Kentucky, Lexington (B.P.D., A.P., D.E.B.)
| | - Makoto Ono
- Division of Cardiology and Rehabilitation, Tamaki Hospital, Japan (M.O.)
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2
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Whisenant CC, Shaw RM. Internal translation of Gja1 (Connexin43) to produce GJA1-20k: Implications for arrhythmia and ischemic-preconditioning. Front Physiol 2022; 13:1058954. [PMID: 36569758 PMCID: PMC9768480 DOI: 10.3389/fphys.2022.1058954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022] Open
Abstract
Internal translation is a form of post-translation modification as it produces different proteins from one mRNA molecule by beginning translation at a methionine coding triplet downstream of the first methionine. Internal translation can eliminate domains of proteins that otherwise restrict movement or activity, thereby creating profound functional diversity. Connexin43 (Cx43), encoded by the gene Gja1, is the main gap junction protein necessary for propagating action potentials between adjacent cardiomyocytes. Gja1 can be internally translated to produce a peptide 20 kD in length named GJA1-20k. This review focuses on the role of GJA1-20k in maintaining cardiac electrical rhythm as well as in ischemic preconditioning (IPC). Connexin43 is the only ion channel we are aware that has been reported to be subject to internal translation. We expect many other ion channels also undergo internal translation. The exploration of post-translational modification of ion channels, and in particular of internal translation, has the potential to greatly increase our understanding of both canonical and non-canonical ion channel biology.
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Su XL, Wang SH, Komal S, Cui LG, Ni RC, Zhang LR, Han SN. The caspase-1 inhibitor VX765 upregulates connexin 43 expression and improves cell-cell communication after myocardial infarction via suppressing the IL-1β/p38 MAPK pathway. Acta Pharmacol Sin 2022; 43:2289-2301. [PMID: 35132192 PMCID: PMC9433445 DOI: 10.1038/s41401-021-00845-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 12/15/2021] [Indexed: 02/04/2023] Open
Abstract
Connexin 43 (Cx43) is the most important protein in the gap junction channel between cardiomyocytes. Abnormalities of Cx43 change the conduction velocity and direction of cardiomyocytes, leading to reentry and conduction block of the myocardium, thereby causing arrhythmia. It has been shown that IL-1β reduces the expression of Cx43 in astrocytes and cardiomyocytes in vitro. However, whether caspase-1 and IL-1β affect connexin 43 after myocardial infarction (MI) is uncertain. In this study we investigated the effects of VX765, a caspase-1 inhibitor, on the expression of Cx43 and cell-to-cell communication after MI. Rats were treated with VX765 (16 mg/kg, i.v.) 1 h before the left anterior descending artery (LAD) ligation, and then once daily for 7 days. The ischemic heart was collected for histochemical analysis and Western blot analysis. We showed that VX765 treatment significantly decreased the infarct area, and alleviated cardiac dysfunction and remodeling by suppressing the NLRP3 inflammasome/caspase-1/IL-1β expression in the heart after MI. In addition, VX765 treatment markedly raised Cx43 levels in the heart after MI. In vitro experiments were conducted in rat cardiac myocytes (RCMs) stimulated with the supernatant from LPS/ATP-treated rat cardiac fibroblasts (RCFs). Pretreatment of the RCFs with VX765 (25 μM) reversed the downregulation of Cx43 expression in RCMs and significantly improved intercellular communication detected using a scrape-loading/dye transfer assay. We revealed that VX765 suppressed the activation of p38 MAPK signaling in the heart tissue after MI as well as in RCMs stimulated with the supernatant from LPS/ATP-treated RCFs. Taken together, these data show that the caspase-1 inhibitor VX765 upregulates Cx43 expression and improves cell-to-cell communication in rat heart after MI via suppressing the IL-1β/p38 MAPK pathway.
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Affiliation(s)
- Xue-Ling Su
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Shu-Hui Wang
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Sumra Komal
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Liu-Gen Cui
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Rui-Cong Ni
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Li-Rong Zhang
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China.
| | - Sheng-Na Han
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China.
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Shimura D, Shaw RM. GJA1-20k and Mitochondrial Dynamics. Front Physiol 2022; 13:867358. [PMID: 35399255 PMCID: PMC8983841 DOI: 10.3389/fphys.2022.867358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 03/08/2022] [Indexed: 01/07/2023] Open
Abstract
Connexin 43 (Cx43) is the primary gap junction protein of mammalian heart ventricles and is encoded by the gene Gja1 which has a single coding exon and therefore cannot be spliced. We previously identified that Gja1 mRNA undergoes endogenous internal translation initiated at one of several internal AUG (M) start codons, generating N-terminal truncated protein isoforms that retain the C-terminus distal to the start site. GJA1-20k, whose translation initiates at mRNA M213, is usually the most abundant isoform in cells and greatly increases after ischemic and metabolic stress. GJA1-20k consists of a small segment of the last transmembrane domain and the complete C-terminus tail of Cx43, with a total size of about 20 kDa. The original role identified for GJA1-20k is as an essential subunit that facilitates the trafficking of full-length Cx43 hexameric hemichannels to cell-cell contacts, generating traditional gap junctions between adjacent cells facilitating, in cardiac muscle, efficient spread of electrical excitation. GJA1-20k deficient mice (generated by a M213L substitution in Gja1) suffer poor electrical coupling between cardiomycytes and arrhythmogenic sudden death two to 4 weeks after their birth. We recently identified that exogenous GJA1-20k expression also mimics the effect of ischemic preconditioning in mouse heart. Furthermore, GJA1-20k localizes to the mitochondrial outer membrane and induces a protective and DRP1 independent form of mitochondrial fission, preserving ATP production and generating less reactive oxygen species (ROS) under metabolic stress, providing powerful protection of myocardium to ischemic insult. In this manuscript, we focus on the detailed roles of GJA1-20k in mitochondria, and its interaction with the actin cytoskeleton.
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Seeing Is Believing: Gap Junctions in Motion. BIOLOGY 2021; 10:biology10060494. [PMID: 34199345 PMCID: PMC8227072 DOI: 10.3390/biology10060494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/01/2021] [Indexed: 11/18/2022]
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Xiao S, Shimura D, Baum R, Hernandez DM, Agvanian S, Nagaoka Y, Katsumata M, Lampe PD, Kleber AG, Hong T, Shaw RM. Auxiliary trafficking subunit GJA1-20k protects connexin-43 from degradation and limits ventricular arrhythmias. J Clin Invest 2021; 130:4858-4870. [PMID: 32525845 DOI: 10.1172/jci134682] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 06/03/2020] [Indexed: 12/31/2022] Open
Abstract
Connexin-43 (Cx43) gap junctions provide intercellular coupling, which ensures rapid action potential propagation and synchronized heart contraction. Alterations in Cx43 localization and reductions in gap junction coupling occur in failing hearts, contributing to ventricular arrhythmias and sudden cardiac death. Recent reports have found that an internally translated Cx43 isoform, GJA1-20k, is an auxiliary subunit for the trafficking of Cx43 in heterologous expression systems. Here, we have created a mouse model by using CRISPR technology to mutate a single internal translation initiation site in Cx43 (M213L mutation), which generates full-length Cx43, but not GJA1-20k. We found that GJA1M213L/M213L mice had severely abnormal electrocardiograms despite preserved contractile function, reduced total Cx43, and reduced gap junctions, and they died suddenly at 2 to 4 weeks of age. Heterozygous GJA1M213L/WT mice survived to adulthood with increased ventricular ectopy. Biochemical experiments indicated that cytoplasmic Cx43 had a half-life that was 50% shorter than membrane-associated Cx43. Without GJA1-20k, poorly trafficked Cx43 was degraded. The data support that GJA1-20k, an endogenous entity translated independently of Cx43, is critical for Cx43 gap junction trafficking, maintenance of Cx43 protein, and normal electrical function of the mammalian heart.
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Affiliation(s)
- Shaohua Xiao
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Neurology, UCLA, Los Angeles, California, USA
| | - Daisuke Shimura
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
| | - Rachel Baum
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Diana M Hernandez
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Sosse Agvanian
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Yoshiko Nagaoka
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Makoto Katsumata
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Paul D Lampe
- Translational Research Program, Public Health Sciences and Human Biology Divisions, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Andre G Kleber
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - TingTing Hong
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Robin M Shaw
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
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Connexin 43 prevents the progression of diabetic renal tubulointerstitial fibrosis by regulating the SIRT1-HIF-1α signaling pathway. Clin Sci (Lond) 2021; 134:1573-1592. [PMID: 32558900 DOI: 10.1042/cs20200171] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/10/2020] [Accepted: 06/19/2020] [Indexed: 12/13/2022]
Abstract
Hyperglycemia-induced renal epithelial-to-mesenchymal transition (EMT) is a key pathological factor in diabetic renal tubulointerstitial fibrosis (RIF). Our previous studies have shown that connexin 43 (Cx43) activation attenuated the development of diabetic renal fibrosis. However, whether Cx43 regulates the EMT of renal tubular epithelial cells (TECs) and the pathological process of RIF under the diabetic conditions remains to be elucidated. In the present study, we identified that Cx43 protein expression was down-regulated in the kidney tissues of db/db mice as well as in high glucose (HG)-induced NRK-52E cells. Overexpression of Cx43 improved renal function in db/db spontaneous diabetic model mice, increased SIRT1 levels, decreased hypoxia-inducible factor (HIF)-1α expression, and reduced production of EMT markers and extracellular matrix (ECM) components. Additionally, Cx43 overexpression inhibited the EMT process and reduced the expression of ECM components such as fibronectin (FN), Collagen I, and Collagen IV in HG-induced NRK-52E cells, whereas Cx43 deficiency had the opposite effects. Mechanistically, Cx43 in a carboxyl-terminal signal transduction-dependent manner could up-regulate SIRT1 expression and enhance SIRT1-dependent deacetylation of HIF-1α to reduce HIF-1α activity, which eventually ameliorated renal EMT and diabetic RIF. Our study indicates the essential role of Cx43 in regulating renal EMT and diabetic RIF via regulating the SIRT1-HIF-1α signaling pathway and provides an experimental basis for Cx43 as a potential target for diabetic nephropathy (DN).
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Mulkearns-Hubert EE, Reizes O, Lathia JD. Connexins in Cancer: Jekyll or Hyde? Biomolecules 2020; 10:E1654. [PMID: 33321749 PMCID: PMC7764653 DOI: 10.3390/biom10121654] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 12/16/2022] Open
Abstract
The expression, localization, and function of connexins, the protein subunits that comprise gap junctions, are often altered in cancer. In addition to cell-cell coupling through gap junction channels, connexins also form hemichannels that allow communication between the cell and the extracellular space and perform non-junctional intracellular activities. Historically, connexins have been considered tumor suppressors; however, they can also serve tumor-promoting functions in some contexts. Here, we review the literature surrounding connexins in cancer cells in terms of specific connexin functions and propose that connexins function upstream of most, if not all, of the hallmarks of cancer. The development of advanced connexin targeting approaches remains an opportunity for the field to further interrogate the role of connexins in cancer phenotypes, particularly through the use of in vivo models. More specific modulators of connexin function will both help elucidate the functions of connexins in cancer and advance connexin-specific therapies in the clinic.
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Affiliation(s)
- Erin E. Mulkearns-Hubert
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (O.R.); (J.D.L.)
| | - Ofer Reizes
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (O.R.); (J.D.L.)
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College, Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
| | - Justin D. Lathia
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (O.R.); (J.D.L.)
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College, Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
- Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic, Cleveland, OH, 44195, USA
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9
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Strauss RE, Gourdie RG. Cx43 and the Actin Cytoskeleton: Novel Roles and Implications for Cell-Cell Junction-Based Barrier Function Regulation. Biomolecules 2020; 10:E1656. [PMID: 33321985 PMCID: PMC7764618 DOI: 10.3390/biom10121656] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
Barrier function is a vital homeostatic mechanism employed by epithelial and endothelial tissue. Diseases across a wide range of tissue types involve dynamic changes in transcellular junctional complexes and the actin cytoskeleton in the regulation of substance exchange across tissue compartments. In this review, we focus on the contribution of the gap junction protein, Cx43, to the biophysical and biochemical regulation of barrier function. First, we introduce the structure and canonical channel-dependent functions of Cx43. Second, we define barrier function and examine the key molecular structures fundamental to its regulation. Third, we survey the literature on the channel-dependent roles of connexins in barrier function, with an emphasis on the role of Cx43 and the actin cytoskeleton. Lastly, we discuss findings on the channel-independent roles of Cx43 in its associations with the actin cytoskeleton and focal adhesion structures highlighted by PI3K signaling, in the potential modulation of cellular barriers. Mounting evidence of crosstalk between connexins, the cytoskeleton, focal adhesion complexes, and junctional structures has led to a growing appreciation of how barrier-modulating mechanisms may work together to effect solute and cellular flux across tissue boundaries. This new understanding could translate into improved therapeutic outcomes in the treatment of barrier-associated diseases.
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Affiliation(s)
- Randy E. Strauss
- Virginia Tech, Translational Biology Medicine and Health (TBMH) Program, Roanoke, VA 24016, USA
| | - Robert G. Gourdie
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA 24016, USA
- Virginia Tech Carilion School of Medicine, Roanoke, VA 24016, USA
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
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Boucher J, Balandre AC, Debant M, Vix J, Harnois T, Bourmeyster N, Péraudeau E, Chépied A, Clarhaut J, Debiais F, Monvoisin A, Cronier L. Cx43 Present at the Leading Edge Membrane Governs Promigratory Effects of Osteoblast-Conditioned Medium on Human Prostate Cancer Cells in the Context of Bone Metastasis. Cancers (Basel) 2020; 12:cancers12103013. [PMID: 33081404 PMCID: PMC7602984 DOI: 10.3390/cancers12103013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 12/12/2022] Open
Abstract
Simple Summary In its late stages, prostate cancer (PCa) is characterized by a high propensity to form osteoblastic bone metastases, mainly treated by palliative approaches. In a previous work, we demonstrated that a gap junctional protein, connexin43 (Cx43) is implicated both in the increase of aggressiveness of PCa cells and in their impact on bone. To analyze the reciprocal part of the dialogue, the current study addresses the role of Cx43 in the impact of bone microenvironment on PCa cells abilities. Using Cx43-overexpressing PCa cell lines, we determined that Cx43 is necessary for promigratory effect induced by osteoblastic conditioned media (ObCM) on individual cells. Next, we demonstrated the requirement of Cx43 membrane localization at the leading edge and the involvement of the cytoplasmic part in this ObCM-induced migration. Overall, our findings precise the role of Cx43 during PCa progression and its putative use as aggressiveness marker and as potential therapeutic targets. Abstract Among the different interacting molecules implicated in bone metastases, connexin43 (Cx43) may increase sensitivity of prostate cancer (PCa) cells to bone microenvironment, as suggested by our in silico and human tissue samples analyses that revealed increased level of Cx43 expression with PCa progression and a Cx43 specific expression in bone secondary sites. The goal of the present study was to understand how Cx43 influences PCa cells sensitivity and aggressiveness to bone microenvironment. By means of Cx43-overexpressing PCa cell lines, we revealed a Cx43-dependent promigratory effect of osteoblastic conditioned media (ObCM). This effect on directional migration relied on the presence of Cx43 at the plasma membrane and not on gap junctional intercellular communication and hemichannel functions. ObCM stimulation induced Rac1 activation and Cx43 interaction with cortactin in protrusions of migrating PCa cells. Finally, by transfecting two different truncated forms of Cx43 in LNCaP cells, we determined that the carboxy terminal (CT) part of Cx43 is crucial for the responsiveness of PCa cells to ObCM. Our study demonstrates that Cx43 level and its membrane localization modulate the phenotypic response of PCa cells to osteoblastic microenvironment and that its CT domain plays a pivotal role.
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Affiliation(s)
- Jonathan Boucher
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
| | - Annie-Claire Balandre
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
| | - Marjolaine Debant
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
| | - Justine Vix
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
- Department of Rheumatology, University Hospital Center of Poitiers, 2 Rue de la Milétrie, 86021 Poitiers, France
| | - Thomas Harnois
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
| | - Nicolas Bourmeyster
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
| | - Elodie Péraudeau
- University Hospital Center of Poitiers, 2 rue de la Milétrie, 86021 Poitiers, France; (E.P.); (J.C.)
- CNRS UMR 7285, Institut de Chimie des Milieux et des Matériaux de Poitiers (IC2MP), University of Poitiers, 4 Rue Michel Brunet, TSA 51106, CEDEX 09, 86073 Poitiers, France
| | - Amandine Chépied
- Laboratory of Experimental and Clinical Neurosciences, LNEC-INSERM U1084, UBM-Laboratoire de Cancérologie Biologique, CHU de Poitiers, 2 Rue de la Milétrie, 86000 Poitiers, France;
| | - Jonathan Clarhaut
- University Hospital Center of Poitiers, 2 rue de la Milétrie, 86021 Poitiers, France; (E.P.); (J.C.)
- CNRS UMR 7285, Institut de Chimie des Milieux et des Matériaux de Poitiers (IC2MP), University of Poitiers, 4 Rue Michel Brunet, TSA 51106, CEDEX 09, 86073 Poitiers, France
| | - Françoise Debiais
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
- Department of Rheumatology, University Hospital Center of Poitiers, 2 Rue de la Milétrie, 86021 Poitiers, France
| | - Arnaud Monvoisin
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
| | - Laurent Cronier
- CNRS ERL7003, Laboratory Signalisation et Transports Ioniques Membranaires (STIM), University of Poitiers, 1 rue Georges Bonnet, TSA 51106, CEDEX 09, 86073 Poitiers, France; (J.B.); (A.-C.B.); (M.D.); (J.V.); (T.H.); (N.B.); (F.D.); (A.M.)
- Correspondence: ; Tel.: +33-5-49-45-37-52
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11
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Dynamic UTR Usage Regulates Alternative Translation to Modulate Gap Junction Formation during Stress and Aging. Cell Rep 2020; 27:2737-2747.e5. [PMID: 31141695 PMCID: PMC6857847 DOI: 10.1016/j.celrep.2019.04.114] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/20/2019] [Accepted: 04/29/2019] [Indexed: 11/22/2022] Open
Abstract
Connexin43 (Cx43; gene name GJA1) is the most ubiquitously expressed gap junction protein, and understanding of its regulation largely falls under transcription and post-translational modification. In addition to Cx43, Gja1 mRNA encodes internally translated isoforms regulating gap junction formation, whose expression is modulated by TGF-β. Here, using RLM-RACE, we identify distinct Gja1 transcripts differing only in 5′ UTR length, of which two are upregulated during TGF-β exposure and hypoxia. Introduction of these transcripts into Gja1−/− cells phenocopies the response of Gja1 to TGF-β with reduced internal translation initiation. Inhibiting pathways downstream of TGF-β selectively regulates levels of Gja1 transcript isoforms and translation products. Reporter assays reveal enhanced translation of full-length Cx43 from shorter Gja1 5′ UTR isoforms. We also observe a correlation among UTR selection, translation, and reduced gap junction formation in aged heart tissue. These data elucidate a relationship between transcript isoform expression and translation initiation regulating intercellular communication. Connexin43 gap junctions enable direct intercellular communication facilitating action potential propagation. Internal translation of connexin43 mRNA generates the truncated isoform GJA1–20k, which promotes gap junction formation. During aging, Zeitz et al. find that activation of stress-response pathways shortens connexin43 mRNA UTRs to limit GJA1–20k translation coincident with gap junction loss.
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12
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Lucero CM, Andrade DC, Toledo C, Díaz HS, Pereyra KV, Diaz-Jara E, Schwarz KG, Marcus NJ, Retamal MA, Quintanilla RA, Del Rio R. Cardiac remodeling and arrhythmogenesis are ameliorated by administration of Cx43 mimetic peptide Gap27 in heart failure rats. Sci Rep 2020; 10:6878. [PMID: 32327677 PMCID: PMC7181683 DOI: 10.1038/s41598-020-63336-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/03/2020] [Indexed: 11/20/2022] Open
Abstract
Alterations in connexins and specifically in 43 isoform (Cx43) in the heart have been associated with a high incidence of arrhythmogenesis and sudden death in several cardiac diseases. We propose to determine salutary effect of Cx43 mimetic peptide Gap27 in the progression of heart failure. High-output heart failure was induced by volume overload using the arterio-venous fistula model (AV-Shunt) in adult male rats. Four weeks after AV-Shunt surgery, the Cx43 mimetic peptide Gap27 or scrambled peptide, were administered via osmotic minipumps (AV-ShuntGap27 or AV-ShuntScr) for 4 weeks. Cardiac volumes, arrhythmias, function and remodeling were determined at 8 weeks after AV-Shunt surgeries. At 8th week, AV-ShuntGap27 showed a marked decrease in the progression of cardiac deterioration and showed a significant improvement in cardiac functions measured by intraventricular pressure-volume loops. Furthermore, AV-ShuntGap27 showed less cardiac arrhythmogenesis and cardiac hypertrophy index compared to AV-ShuntScr. Gap27 treatment results in no change Cx43 expression in the heart of AV-Shunt rats. Our results strongly suggest that Cx43 play a pivotal role in the progression of cardiac dysfunction and arrhythmogenesis in high-output heart failure; furthermore, support the use of Cx43 mimetic peptide Gap27 as an effective therapeutic tool to reduce the progression of cardiac dysfunction in high-output heart failure.
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Affiliation(s)
- Claudia M Lucero
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.,Institute of Biomedical Sciences, Universidad Autónoma de Chile, Santiago, Chile
| | - David C Andrade
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación en Fisiología del Ejercicio, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Camilo Toledo
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Hugo S Díaz
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Katherin V Pereyra
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Esteban Diaz-Jara
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Karla G Schwarz
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Noah J Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA, USA
| | - Mauricio A Retamal
- Universidad del Desarrollo, Centro de Fisiología Celular e Integrativa, Clínica Alemana Facultad de Medicina, Santiago, Chile
| | | | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Centro de Envejecimiento y Regeneración (CARE-UC), Pontificia Universidad Católica de Chile, Santiago, Chile. .,Centro de Excelencia de Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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13
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Chen W, Zheng P, Hong T, Wang Y, Liu N, He B, Zou S, Ren D, Duan J, Zhao L, Feng J. Astrocytes‐derived exosomes induce neuronal recovery after traumatic brain injury via delivering gap junction alpha 1‐20 k. J Tissue Eng Regen Med 2020; 14:412-423. [PMID: 31826322 DOI: 10.1002/term.3002] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 10/21/2019] [Accepted: 11/11/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Wei Chen
- Emergency Trauma CenterThe First Affiliated Hospital of Nanchang University Nanchang China
| | - Ping Zheng
- Department of NeurosurgeryThe People's Hospital of Shanghai Pudong New Area Affiliated to Shanghai University of Medicine and Health Sciences Shanghai China
| | - Tao Hong
- Emergency Trauma CenterThe First Affiliated Hospital of Nanchang University Nanchang China
| | - Yang Wang
- Emergency Trauma CenterThe First Affiliated Hospital of Nanchang University Nanchang China
| | - Ning Liu
- Department of NeurosurgeryThe First Affiliated Hospital of Nanjing Medical University Nanjing China
| | - Bin He
- Department of NeurosurgeryThe People's Hospital of Shanghai Pudong New Area Affiliated to Shanghai University of Medicine and Health Sciences Shanghai China
| | - Shufeng Zou
- Emergency Trauma CenterThe First Affiliated Hospital of Nanchang University Nanchang China
| | - Dabin Ren
- Department of NeurosurgeryThe People's Hospital of Shanghai Pudong New Area Affiliated to Shanghai University of Medicine and Health Sciences Shanghai China
| | - Jian Duan
- Emergency Trauma CenterThe First Affiliated Hospital of Nanchang University Nanchang China
| | - Lin Zhao
- Department of NeurosurgeryThe First Affiliated Hospital of Nanjing Medical University Nanjing China
| | - Jiugeng Feng
- Emergency Trauma CenterThe First Affiliated Hospital of Nanchang University Nanchang China
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14
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Totland MZ, Rasmussen NL, Knudsen LM, Leithe E. Regulation of gap junction intercellular communication by connexin ubiquitination: physiological and pathophysiological implications. Cell Mol Life Sci 2020; 77:573-591. [PMID: 31501970 PMCID: PMC7040059 DOI: 10.1007/s00018-019-03285-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 08/10/2019] [Accepted: 08/16/2019] [Indexed: 12/15/2022]
Abstract
Gap junctions consist of arrays of intercellular channels that enable adjacent cells to communicate both electrically and metabolically. Gap junctions have a wide diversity of physiological functions, playing critical roles in both excitable and non-excitable tissues. Gap junction channels are formed by integral membrane proteins called connexins. Inherited or acquired alterations in connexins are associated with numerous diseases, including heart failure, neuropathologies, deafness, skin disorders, cataracts and cancer. Gap junctions are highly dynamic structures and by modulating the turnover rate of connexins, cells can rapidly alter the number of gap junction channels at the plasma membrane in response to extracellular or intracellular cues. Increasing evidence suggests that ubiquitination has important roles in the regulation of endoplasmic reticulum-associated degradation of connexins as well as in the modulation of gap junction endocytosis and post-endocytic sorting of connexins to lysosomes. In recent years, researchers have also started to provide insights into the physiological roles of connexin ubiquitination in specific tissue types. This review provides an overview of the advances made in understanding the roles of connexin ubiquitination in the regulation of gap junction intercellular communication and discusses the emerging physiological and pathophysiological implications of these processes.
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Affiliation(s)
- Max Zachrisson Totland
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Nikoline Lander Rasmussen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
- Department of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Lars Mørland Knudsen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Edward Leithe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway.
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway.
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15
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Aasen T, Sansano I, Montero MÁ, Romagosa C, Temprana-Salvador J, Martínez-Marti A, Moliné T, Hernández-Losa J, Ramón y Cajal S. Insight into the Role and Regulation of Gap Junction Genes in Lung Cancer and Identification of Nuclear Cx43 as a Putative Biomarker of Poor Prognosis. Cancers (Basel) 2019; 11:cancers11030320. [PMID: 30845770 PMCID: PMC6468764 DOI: 10.3390/cancers11030320] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 02/25/2019] [Accepted: 03/02/2019] [Indexed: 12/12/2022] Open
Abstract
Direct intercellular communication, mediated by gap junctions formed by the connexin transmembrane protein family, is frequently dysregulated in cancer. Connexins have been described as tumour suppressors, but emerging evidence suggests that they can also act as tumour promoters. This feature is connexin- and tissue-specific and may be mediated by complex signalling pathways through gap junctions or hemichannels or by completely junction-independent events. Lung cancer is the number one cancer in terms of mortality worldwide, and novel biomarkers and therapeutic targets are urgently needed. Our objective was to gain a better understanding of connexins in this setting. We used several in silico tools to analyse TCGA data in order to compare connexin mRNA expression between healthy lung tissue and lung tumours and correlated these results with gene methylation patterns. Using Kaplan-Meier plotter tools, we analysed a microarray dataset and an RNA-seq dataset of non-small cell lung tumours in order to correlate connexin expression with patient prognosis. We found that connexin mRNA expression is frequently either upregulated or downregulated in lung tumours. This correlated with both good and poor prognosis (overall survival) in a clear connexin isoform-dependent manner. These associations were strongly influenced by the histological subtype (adenocarcinoma versus squamous cell carcinoma). We present an overview of all connexins but particularly focus on four isoforms implicated in lung cancer: Cx26, Cx30.3, Cx32 and Cx43. We further analysed the protein expression and localization of Cx43 in a series of 73 human lung tumours. We identified a subset of tumours that exhibited a unique strong nuclear Cx43 expression pattern that predicted worse overall survival (p = 0.014). Upon sub-stratification, the prognostic value remained highly significant in the adenocarcinoma subtype (p = 0.002) but not in the squamous carcinoma subtype (p = 0.578). This finding highlights the importance of analysis of connexin expression at the protein level, particularly the subcellular localization. Elucidation of the underlying pathways regulating Cx43 localization may provide for novel therapeutic opportunities.
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Affiliation(s)
- Trond Aasen
- Translational Molecular Pathology, Vall d'Hebron Research Institute (VHIR), Barcelona 08035, Spain.
| | - Irene Sansano
- Pathology Department, Vall d'Hebron University Hospital, Barcelona 08035, Spain.
| | | | - Cleofé Romagosa
- Pathology Department, Vall d'Hebron University Hospital, Barcelona 08035, Spain.
| | | | | | - Teresa Moliné
- Pathology Department, Vall d'Hebron University Hospital, Barcelona 08035, Spain.
| | | | - Santiago Ramón y Cajal
- Translational Molecular Pathology, Vall d'Hebron Research Institute (VHIR), Barcelona 08035, Spain.
- Pathology Department, Vall d'Hebron University Hospital, Barcelona 08035, Spain.
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16
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Spagnol G, Trease AJ, Zheng L, Gutierrez M, Basu I, Sarmiento C, Moore G, Cervantes M, Sorgen PL. Connexin43 Carboxyl-Terminal Domain Directly Interacts with β-Catenin. Int J Mol Sci 2018; 19:ijms19061562. [PMID: 29882937 PMCID: PMC6032326 DOI: 10.3390/ijms19061562] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/18/2018] [Accepted: 05/22/2018] [Indexed: 12/13/2022] Open
Abstract
Activation of Wnt signaling induces Connexin43 (Cx43) expression via the transcriptional activity of β-catenin, and results in the enhanced accumulation of the Cx43 protein and the formation of gap junction channels. In response to Wnt signaling, β-catenin co-localizes with the Cx43 protein itself as part of a complex at the gap junction plaque. Work from several labs have also shown indirect evidence of this interaction via reciprocal co-immunoprecipitation. Our goal for the current study was to identify whether β-catenin directly interacts with Cx43, and if so, the location of that direct interaction. Identifying residues involved in direct protein⁻protein interaction is of importance when they are correlated to the phosphorylation of Cx43, as phosphorylation can modify the binding affinities of Cx43 regulatory protein partners. Therefore, combining the location of a protein partner interaction on Cx43 along with the phosphorylation pattern under different homeostatic and pathological conditions will be crucial information for any potential therapeutic intervention. Here, we identified that β-catenin directly interacts with the Cx43 carboxyl-terminal domain, and that this interaction would be inhibited by the Src phosphorylation of Cx43CT residues Y265 and Y313.
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Affiliation(s)
- Gaelle Spagnol
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Andrew J Trease
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Li Zheng
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Mirtha Gutierrez
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Ishika Basu
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Cleofes Sarmiento
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Gabriella Moore
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Matthew Cervantes
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Paul L Sorgen
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
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17
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Aasen T, Johnstone S, Vidal-Brime L, Lynn KS, Koval M. Connexins: Synthesis, Post-Translational Modifications, and Trafficking in Health and Disease. Int J Mol Sci 2018; 19:ijms19051296. [PMID: 29701678 PMCID: PMC5983588 DOI: 10.3390/ijms19051296] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/20/2018] [Accepted: 04/21/2018] [Indexed: 02/06/2023] Open
Abstract
Connexins are tetraspan transmembrane proteins that form gap junctions and facilitate direct intercellular communication, a critical feature for the development, function, and homeostasis of tissues and organs. In addition, a growing number of gap junction-independent functions are being ascribed to these proteins. The connexin gene family is under extensive regulation at the transcriptional and post-transcriptional level, and undergoes numerous modifications at the protein level, including phosphorylation, which ultimately affects their trafficking, stability, and function. Here, we summarize these key regulatory events, with emphasis on how these affect connexin multifunctionality in health and disease.
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Affiliation(s)
- Trond Aasen
- Translational Molecular Pathology, Vall d'Hebron Institute of Research (VHIR), Autonomous University of Barcelona, CIBERONC, 08035 Barcelona, Spain.
| | - Scott Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, P.O. Box 801394, Charlottesville, VI 22908, USA.
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, UK.
| | - Laia Vidal-Brime
- Translational Molecular Pathology, Vall d'Hebron Institute of Research (VHIR), Autonomous University of Barcelona, CIBERONC, 08035 Barcelona, Spain.
| | - K Sabrina Lynn
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Michael Koval
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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18
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Fu Y, Zhang SS, Xiao S, Basheer WA, Baum R, Epifantseva I, Hong T, Shaw RM. Cx43 Isoform GJA1-20k Promotes Microtubule Dependent Mitochondrial Transport. Front Physiol 2017; 8:905. [PMID: 29163229 PMCID: PMC5682029 DOI: 10.3389/fphys.2017.00905] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/25/2017] [Indexed: 01/26/2023] Open
Abstract
Connexin 43 (Cx43, encoded by GJA1) is a cell-cell communication gap junction protein expressed in all organ systems. It was recently found that GJA1 mRNA undergoes alternative translation to generate N-terminal truncated isoforms, of which GJA1-20k is the most abundant. Here we report a surprising finding that, unlike full length GJA1-43k, GJA1-20k has a strong tropism for mitochondria. Exploring function, we found that GJA1-20k appears to be an organelle chaperone and that overexpression of GJA1-20k is sufficient to rescue mitochondrial localization to the cell periphery upon exposure to hydrogen peroxide, which effectively limits the network fragmentation that occurs with oxidative stress. By high-resolution fluorescent imaging and electron microscopy, we determined that GJA1-20k is enriched at the interface between mitochondria and microtubules, appearing to load organelles for transport. Mutagenesis experiments revealed that although the microtubule-binding domain (MTBD) in GJA1-20k is not necessary for protein localization to mitochondria, the MTBD is essential for GJA1-20k to facilitate mitochondrial transport and maintain mitochondrial localization at the periphery. These results reveal an unexpected role for the alternatively translated isoform of the Cx43 gap junction protein, GJA1-20k, which is to facilitate microtubule-based mitochondrial transport and to maintain mitochondrial network integrity during cellular stress.
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Affiliation(s)
- Ying Fu
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States
| | - Shan-Shan Zhang
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States
| | - Shaohua Xiao
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States
| | - Wassim A Basheer
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States
| | - Rachel Baum
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States
| | - Irina Epifantseva
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States
| | - TingTing Hong
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States.,Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Robin M Shaw
- Cedars-Sinai Medical Center, Cedars-Sinai Heart Institute, Los Angeles, CA, United States.,Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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19
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Basheer WA, Xiao S, Epifantseva I, Fu Y, Kleber AG, Hong T, Shaw RM. GJA1-20k Arranges Actin to Guide Cx43 Delivery to Cardiac Intercalated Discs. Circ Res 2017; 121:1069-1080. [PMID: 28923791 DOI: 10.1161/circresaha.117.311955] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 01/21/2023]
Abstract
RATIONALE Delivery of Cx43 (connexin 43) to the intercalated disc is a continuous and rapid process critical for intercellular coupling. By a pathway of targeted delivery involving microtubule highways, vesicles of Cx43 hemichannels are efficiently trafficked to adherens junctions at intercalated discs. It has also been identified that actin provides rest stops for Cx43 forward trafficking and that Cx43 has a 20 kDa internally translated small C terminus isoform, GJA1-20k (Gap Junction Protein Alpha 1- 20 kDa), which is required for full-length Cx43 trafficking, but by an unknown mechanism. OBJECTIVE We explored the mechanism by which the GJA1-20k isoform is required for full-length Cx43 forward trafficking to intercalated discs. METHODS AND RESULTS Using an in vivo Adeno-associated virus serotype 9-mediated gene transfer system, we confirmed in whole animal that GJA1-20k markedly increases endogenous myocardial Cx43 gap junction plaque size at the intercalated discs. In micropatterned cell pairing systems, we found that exogenous GJA1-20k expression stabilizes filamentous actin without affecting actin protein expression and that GJA1-20k complexes with both actin and tubulin. We also found that filamentous actin regulates microtubule organization as inhibition of actin polymerization with a low dose of latrunculin A disrupts the targeting of microtubules to cell-cell junctions. GJA1-20k protects actin filament from latrunculin A disruption, preserving microtubule trajectory to the cell-cell border. For therapeutic implications, we found that prior in vivo Adeno-associated virus serotype 9-mediated gene delivery of GJA1-20k to the heart protects Cx43 localization to the intercalated discs against acute ischemic injury. CONCLUSIONS The internally translated GJA1-20k isoform stabilizes actin filaments, which guides growth trajectories of the Cx43 microtubule trafficking machinery, increasing delivery of Cx43 hemichannels to cardiac intercalated discs. Exogenous GJA1-20k helps to maintain cell-cell coupling in instances of anticipated myocardial ischemia.
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Affiliation(s)
- Wassim A Basheer
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.)
| | - Shaohua Xiao
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.)
| | - Irina Epifantseva
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.)
| | - Ying Fu
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.)
| | - Andre G Kleber
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.)
| | - TingTing Hong
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.)
| | - Robin M Shaw
- From the Cedars-Sinai Heart Institute (W.A.B., S.X., I.E., Y.F., T.H., R.M.S.) and Department of Medicine (T.H., R.M.S.), Cedars-Sinai Medical Center and UCLA, Los Angeles, CA; and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (A.G.K.).
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20
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Epifantseva I, Shaw RM. Intracellular trafficking pathways of Cx43 gap junction channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:40-47. [PMID: 28576298 DOI: 10.1016/j.bbamem.2017.05.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/19/2017] [Accepted: 05/25/2017] [Indexed: 12/11/2022]
Abstract
Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Irina Epifantseva
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Robin M Shaw
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.; Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA..
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21
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Esseltine JL, Laird DW. Next-Generation Connexin and Pannexin Cell Biology. Trends Cell Biol 2016; 26:944-955. [PMID: 27339936 DOI: 10.1016/j.tcb.2016.06.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/02/2016] [Accepted: 06/06/2016] [Indexed: 01/17/2023]
Abstract
Connexins and pannexins are two families of large-pore channel forming proteins that are capable of passing small signaling molecules. While connexins serve the seminal task of direct gap junctional intercellular communication, pannexins are far less understood but function primarily as single membrane channels in autocrine and paracrine signaling. Advancements in connexin and pannexin biology in recent years has revealed that in addition to well-described classical functions at the plasma membrane, exciting new evidence suggests that connexins and pannexins participate in alternative pathways involving multiple intracellular compartments. Here we briefly highlight classical functions of connexins and pannexins but focus our attention mostly on the transformative findings that suggest that these channel-forming proteins may serve roles far beyond our current understandings.
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Affiliation(s)
- Jessica L Esseltine
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
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