1
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Xiong X, Chen W, Chen C, Wu Q, He C. Analysis of the function and therapeutic strategy of connexin 43 from its subcellular localization. Biochimie 2024; 218:1-7. [PMID: 37611889 DOI: 10.1016/j.biochi.2023.08.011] [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: 04/04/2023] [Revised: 08/07/2023] [Accepted: 08/18/2023] [Indexed: 08/25/2023]
Abstract
Connexins (Cxs) are a family of transmembrane proteins located in the plasma membrane of human cells, among which connexin 43 (Cx43) is abundantly expressed in various types of human cells. Cx43, encoded by the gap junction protein alpha 1 (GJA1) gene, assembles into a hexameric structure in the Golgi apparatus and translocates to the plasma membrane to form hemichannels (Hcs), which pair with those of the cells in contact with each other and form gap junction intercellular communication (GJIC). The role of Cx43 as a connexin localized at the plasma membrane to perform channel functions is well recognized in previous studies, but recent studies have found that it can also be localized in the nucleus, mitochondria, or present in extracellular vesicles (EVs) and tunneling nanotubes (TNTs). Cx43 in the nucleus is involved in gene transcription regulation, cytoskeleton formation, cell migration and adhesion. Cx43 in mitochondria is involved in mitochondrial respiration-related functions, and Cx43 in extracellular vesicles and tunneling nanotubes is involved in distant cellular information exchange. It is because of the diverse distribution of subcellular localization of Cx43 that it is possible to explore the corresponding functions by analyzing its localization. In this review, we summarize the important roles of Cx43 in disease development from the perspective of subcellular localization, and provide new ideas for Cx43 as a therapeutic target and the search for related pathological mechanisms.
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Affiliation(s)
- Xinhai Xiong
- The Second Affiliated Hospital of Hunan Normal University, Changsha, Hunan, 410003, China
| | - Wenjie Chen
- The Second Affiliated Hospital of Hunan Normal University, Changsha, Hunan, 410003, China
| | - Cheng Chen
- The Second Affiliated Hospital of Hunan Normal University, Changsha, Hunan, 410003, China; 926 Hospital of the People's Liberation Army, Kaiyuan, Yunnan, 661600, China.
| | - Qi Wu
- The Second Affiliated Hospital of Hunan Normal University, Changsha, Hunan, 410003, China
| | - Chaopeng He
- The Second Xiangya Hospital, Changsha, Hunan, 410011, China
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2
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Tetenborg S, Liss V, Breitsprecher L, Timonina K, Kotova A, Acevedo Harnecker AJ, Yuan C, Shihabeddin E, Ariakia F, Qin G, Chengzhi C, Dedek K, Zoidl G, Hensel M, O'Brien J. Intralumenal docking of connexin 36 channels in the ER isolates mistrafficked protein. J Biol Chem 2023; 299:105282. [PMID: 37742923 PMCID: PMC10637963 DOI: 10.1016/j.jbc.2023.105282] [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: 03/11/2023] [Revised: 08/30/2023] [Accepted: 09/05/2023] [Indexed: 09/26/2023] Open
Abstract
The intracellular domains of connexins are essential for the assembly of gap junctions. For connexin 36 (Cx36), the major neuronal connexin, it has been shown that a dysfunctional PDZ-binding motif interferes with electrical synapse formation. However, it is still unknown how this motif coordinates the transport of Cx36. In the present study, we characterize a phenotype of Cx36 mutants that lack a functional PDZ-binding motif using HEK293T cells as an expression system. We provide evidence that an intact PDZ-binding motif is critical for proper endoplasmic reticulum (ER) export of Cx36. Removing the PDZ-binding motif of Cx36 results in ER retention and the formation of multimembrane vesicles containing gap junction-like connexin aggregates. Using a combination of site-directed mutagenesis and electron micrographs, we reveal that these vesicles consist of Cx36 channels that docked prematurely in the ER. Our data suggest a model in which ER-retained Cx36 channels reshape the ER membrane into concentric whorls that are released into the cytoplasm.
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Affiliation(s)
| | - Viktoria Liss
- Department of Biology/Chemistry, iBiOs-Integrated Bioimaging Facility, CellNanOs - Center of Cellular Nanoanalytics, Osnabrück, Germany; Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Leonhard Breitsprecher
- Department of Biology/Chemistry, iBiOs-Integrated Bioimaging Facility, CellNanOs - Center of Cellular Nanoanalytics, Osnabrück, Germany; Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Ksenia Timonina
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Anna Kotova
- Department of Biology, York University, Toronto, Ontario, Canada
| | | | - Chunxu Yuan
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Eyad Shihabeddin
- College of Optometry, University of Houston, Houston, Texas, USA; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Fatemeh Ariakia
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Guoting Qin
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Cai Chengzhi
- Department of Chemistry, University of Houston, Houston, Texas, USA
| | - Karin Dedek
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany; Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Georg Zoidl
- Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Department of Biology/Chemistry, iBiOs-Integrated Bioimaging Facility, CellNanOs - Center of Cellular Nanoanalytics, Osnabrück, Germany; Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - John O'Brien
- College of Optometry, University of Houston, Houston, Texas, USA.
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3
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Wang D, Wang H, Fan L, Ludwig T, Wegner A, Stahl F, Harre J, Warnecke A, Zeilinger C. A Chemical Chaperone Restores Connexin 26 Mutant Activity. ACS Pharmacol Transl Sci 2023; 6:997-1005. [PMID: 37470015 PMCID: PMC10353060 DOI: 10.1021/acsptsci.3c00056] [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: 03/14/2023] [Indexed: 07/21/2023]
Abstract
Mutations in connexin 26 (Cx26) cause hearing disorders of a varying degree. Herein, to identify compounds capable of restoring the function of mutated Cx26, a novel miniaturized microarray-based screening system was developed to perform an optical assay of Cx26 functionality. These molecules were identified through a viability assay using HeLa cells expressing wild-type (WT) Cx26, which exhibited sensitivity toward the HSP90 inhibitor radicicol in the submicromolar concentration range. Open Cx26 hemichannels are assumed to mediate the passage of molecules up to 1000 Da in size. Thus, by releasing radicicol, WT Cx26 active hemichannels in HeLa cells contribute to a higher survival rate and lower cell viability when Cx26 is mutated. HeLa cells expressing Cx26 mutations exhibited reduced viability in the presence of radicicol, such as the mutants F161S or R184P. Next, molecules exhibiting chemical chaperoning activity, suspected of restoring channel function, were assessed regarding whether they induced superior sensitivity toward radicicol and increased HeLa cell viability. Through a viability assay and microarray-based flux assay that uses Lucifer yellow in HeLa cells, compounds 3 and 8 were identified to restore mutant functionality. Furthermore, thermophoresis experiments revealed that only 3 (VRT-534) exhibited dose-responsive binding to recombinant WT Cx26 and mutant Cx26K188N with half maximal effective concentration values of 19 and ∼5 μM, respectively. The findings of this study reveal that repurposing compounds already being used to treat other diseases, such as cystic fibrosis, in combination with functional bioassays and binding tests can help identify novel potential candidates that can be used to treat hearing disorders.
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Affiliation(s)
- Dahua Wang
- Gottfried-Wilhelm-Leibniz
University of Hannover, BMWZ (Zentrum für
Biomolekulare Wirkstoffe), Schneiderberg 38, 30167 Hannover, Germany
- Clinic
for Otorhinolaryngology Surgery, Hannover
Medical School (MHH), 30625 Hannover, Germany
| | - Hongling Wang
- Gottfried-Wilhelm-Leibniz
University of Hannover, BMWZ (Zentrum für
Biomolekulare Wirkstoffe), Schneiderberg 38, 30167 Hannover, Germany
- Clinic
for Otorhinolaryngology Surgery, Hannover
Medical School (MHH), 30625 Hannover, Germany
| | - Lu Fan
- Gottfried-Wilhelm-Leibniz
University of Hannover, BMWZ (Zentrum für
Biomolekulare Wirkstoffe), Schneiderberg 38, 30167 Hannover, Germany
- Clinic
for Otorhinolaryngology Surgery, Hannover
Medical School (MHH), 30625 Hannover, Germany
| | - Tobias Ludwig
- Technische
Universität Braunschweig, Braunschweig Integrated Centre of
Systems Biology (BRICS), Department of Bioinformatics
and Biochemistry, Rebenring
56, 38106 Braunschweig, Germany
| | - Andre Wegner
- Technische
Universität Braunschweig, Braunschweig Integrated Centre of
Systems Biology (BRICS), Department of Bioinformatics
and Biochemistry, Rebenring
56, 38106 Braunschweig, Germany
| | - Frank Stahl
- Gottfried-Wilhelm-Leibniz
University of Hannover, Institut für
Technische Chemie/BMWZ (Zentrum für Biomolekulare Wirkstoffe), Callinstr. 5, 30167 Hannover, Germany
| | - Jennifer Harre
- Clinic
for Otorhinolaryngology Surgery, Hannover
Medical School (MHH), 30625 Hannover, Germany
| | - Athanasia Warnecke
- Clinic
for Otorhinolaryngology Surgery, Hannover
Medical School (MHH), 30625 Hannover, Germany
| | - Carsten Zeilinger
- Gottfried-Wilhelm-Leibniz
University of Hannover, BMWZ (Zentrum für
Biomolekulare Wirkstoffe), Schneiderberg 38, 30167 Hannover, Germany
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4
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MiR-130a-3p regulates FUNDC1-mediated mitophagy by targeting GJA1 in myocardial ischemia/reperfusion injury. Cell Death Discov 2023; 9:77. [PMID: 36841811 PMCID: PMC9968299 DOI: 10.1038/s41420-023-01372-7] [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: 11/17/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 02/27/2023] Open
Abstract
Understanding the complex pathogenesis in myocardial ischemia/reperfusion (I/R) injury (IRI) is an urgent problem in clinical trials. Increasing pieces of evidence have suggested that miRNAs are involved in the occurrence and development of heart diseases by regulating mitochondria-related gene expression. Mitochondria have been acknowledged as the key triggers of cardiac I/R injury. However, the potential impact of miR-130a on mitochondria remains unclear in myocardial IRI. Exploring the regulatory mechanism of miR-130a on mitochondria may provide a new target for IRI therapy. In the present study, we found that miR-130a significantly increased in acute myocardial infarction (AMI) patients and myocardial I/R rats. MiR-130a could downregulate the viability of cardiomyocytes and the knockdown of miR-130a could protect the viability of cardiomyocytes under hypoxia-reoxygenation (HR). Over-expression of miR-130a resulted in mitochondrial dysfunction. It was evidenced by decreases in mitochondrial ATP production, mitochondrial membrane potential (MMP), and an increase in reactive oxygen species (ROS) production. However, suppression of miR-130a could protect against mitochondrial damage, show elevation of mitochondrial ATP production rate and MMP, and reduce ROS production. We further explored the effect of miR-130a on the mitochondrial quality control (QMC) system by determining mitochondrial-protein-specific proteases and analyzed mitochondrial morphology by fluorescence imaging and electron microscopy, respectively. It was noted that miR-130a could suppress mitochondrial fusion and FUNDC1-mediated mitophagy to accelerate myocardial IRI. Moreover, we investigated the potential miR-130a targeted mitochondria-related genes to understand the regulatory mechanism of miR-130a in the setting of myocardial IRI. It was revealed that miR-130a targeted GJA1, and GJA1 rescued IRI by enhancing ATP production rate and oxidative phosphorylation, meanwhile protecting cell viability, MMP, and activating mitophagy. In addition, the knockdown of miR-130a significantly activated FUNDC1-mediated mitophagy, while the knockdown of GJA1 reversed the relevant response. Collectively, our findings suggest that miR-130a regulates FUNDC1-mediated mitophagy by targeting GJA1 in myocardial IRI.
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Mitochondrial transfer/transplantation: an emerging therapeutic approach for multiple diseases. Cell Biosci 2022; 12:66. [PMID: 35590379 PMCID: PMC9121600 DOI: 10.1186/s13578-022-00805-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 05/01/2022] [Indexed: 12/16/2022] Open
Abstract
Mitochondria play a pivotal role in energy generation and cellular physiological processes. These organelles are highly dynamic, constantly changing their morphology, cellular location, and distribution in response to cellular stress. In recent years, the phenomenon of mitochondrial transfer has attracted significant attention and interest from biologists and medical investigators. Intercellular mitochondrial transfer occurs in different ways, including tunnelling nanotubes (TNTs), extracellular vesicles (EVs), and gap junction channels (GJCs). According to research on intercellular mitochondrial transfer in physiological and pathological environments, mitochondrial transfer hold great potential for maintaining body homeostasis and regulating pathological processes. Multiple research groups have developed artificial mitochondrial transfer/transplantation (AMT/T) methods that transfer healthy mitochondria into damaged cells and recover cellular function. This paper reviews intercellular spontaneous mitochondrial transfer modes, mechanisms, and the latest methods of AMT/T. Furthermore, potential application value and mechanism of AMT/T in disease treatment are also discussed.
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6
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Subcellular Localization of Connexin 26 in Cardiomyocytes and in Cardiomyocyte-Derived Extracellular Vesicles. Molecules 2021; 26:molecules26216726. [PMID: 34771134 PMCID: PMC8587102 DOI: 10.3390/molecules26216726] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/26/2021] [Accepted: 11/03/2021] [Indexed: 12/13/2022] Open
Abstract
Connexins (Cxs) are a family of membrane-spanning proteins, expressed in vertebrates and named according to their molecular weight. They are involved in tissue homeostasis, and they function by acting at several communication levels. Cardiac Cxs are responsible for regular heart function and, among them, Cx26 and Cx43 are widely expressed throughout the heart. Cx26 is present in vessels, as well as in cardiomyocytes, and its localization is scattered all over the cell aside from at the intercalated discs as is the case for the other cardiac Cxs. However, having been found in cardiomyocytes only recently, both its subcellular localization and its functional characterization in cardiomyocytes remain poorly understood. Therefore, in this study we aimed to obtain further data on the localization of Cx26 at the subcellular level. Our TEM immunogold analyses were performed on rat heart ventricles and differentiated H9c2 cardiac cell sections as well as on differentiated H9c2 derived extracellular vesicles. The results confirmed the absence of Cx26 at intercalated discs and showed the presence of Cx26 at the level of different subcellular compartments. The peculiar localization at the level of extracellular vesicles suggested a specific role for cardiac Cx26 in inter-cellular communication in an independent gap junction manner.
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7
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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8
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Norris RP. Transfer of mitochondria and endosomes between cells by gap junction internalization. Traffic 2021; 22:174-179. [PMID: 33797162 DOI: 10.1111/tra.12786] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/24/2021] [Accepted: 03/29/2021] [Indexed: 12/15/2022]
Abstract
Intercellular organelle transfer has been documented in several cell types and has been proposed to be important for cell-cell communication and cellular repair. However, the mechanisms by which organelle transfer occurs are uncertain. Recent studies indicate that the gap junction protein, connexin 43 (Cx43), is required for mitochondrial transfer but its specific role is unknown. Using three-dimensional electron microscopy and immunogold labeling of Cx43, this report shows that whole organelles including mitochondria and endosomes are incorporated into double-membrane vesicles, called connexosomes or annular gap junctions, that form as a result of gap junction internalization. These findings demonstrate a novel mechanism for intercellular organelle transfer mediated by Cx43 gap junctions.
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Affiliation(s)
- Rachael P Norris
- Department of Cell Biology, UConn Health, Farmington, Connecticut, USA
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9
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Cibelli A, Veronica Lopez-Quintero S, Mccutcheon S, Scemes E, Spray DC, Stout RF, Suadicani SO, Thi MM, Urban-Maldonado M. Generation and Characterization of Immortalized Mouse Cortical Astrocytes From Wildtype and Connexin43 Knockout Mice. Front Cell Neurosci 2021; 15:647109. [PMID: 33790744 PMCID: PMC8005635 DOI: 10.3389/fncel.2021.647109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/18/2021] [Indexed: 11/17/2022] Open
Abstract
We transduced mouse cortical astrocytes cultured from four litters of embryonic wildtype (WT) and connexin43 (Cx43) null mouse pups with lentiviral vector encoding hTERT and measured expression of astrocyte-specific markers up to passage 10 (p10). The immortalized cell lines thus generated (designated IWCA and IKOCA, respectively) expressed biomarkers consistent with those of neonatal astrocytes, including Cx43 from wildtype but not from Cx43-null mice, lack of Cx30, and presence of Cx26. AQP4, the water channel that is found in high abundance in astrocyte end-feet, was expressed at moderately high levels in early passages, and its mRNA and protein declined to low but still detectable levels by p10. The mRNA levels of the astrocyte biomarkers aldehyde dehydrogenase 1L1 (ALDH1L1), glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP) remained relatively constant during successive passages. GS protein expression was maintained while GFAP declined with cell passaging but was still detectable at p10. Both mRNA and protein levels of glutamate transporter 1 (GLT-1) declined with passage number. Immunostaining at corresponding times was consistent with the data from Western blots and provided evidence that these proteins were expressed at appropriate intracellular locations. Consistent with our goal of generating immortalized cell lines in which Cx43 was either functionally expressed or absent, IWCA cells were found to be well coupled with respect to intercellular dye transfer and similar to primary astrocyte cultures in terms of time course of junction formation, electrical coupling strength and voltage sensitivity. Moreover, barrier function was enhanced in co-culture of the IWCA cell line with bEnd.3 microvascular endothelial cells. In addition, immunostaining revealed oblate endogenous Cx43 gap junction plaques in IWCA that were similar in appearance to those plaques obtained following transfection of IKOCA cells with fluorescent protein tagged Cx43. Re-expression of Cx43 in IKOCA cells allows experimental manipulation of connexins and live imaging of interactions between connexins and other proteins. We conclude that properties of these cell lines resemble those of primary cultured astrocytes, and they may provide useful tools in functional studies by facilitating genetic and pharmacological manipulations in the context of an astrocyte-appropriate cellular environment.
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Affiliation(s)
- Antonio Cibelli
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | | | - Sean Mccutcheon
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | - Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | - David C. Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Medicine (Cardiology), Albert Einstein College of Medicine, New York, NY, United States,*Correspondence: David C. Spray,
| | - Randy F. Stout
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, New York, NY, United States,Randy J. Stout Jr.,
| | - Sylvia O. Suadicani
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Urology, Albert Einstein College of Medicine, New York, NY, United States,Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY, United States
| | - Mia M. Thi
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY, United States,Department of Orthopaedic Surgery, Albert Einstein College of Medicine, New York, NY, United States
| | - Marcia Urban-Maldonado
- Department of Urology, Albert Einstein College of Medicine, New York, NY, United States,Department of Orthopaedic Surgery, Albert Einstein College of Medicine, New York, NY, United States
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Norris RP, Terasaki M. Gap junction internalization and processing in vivo: a 3D immuno-electron microscopy study. J Cell Sci 2021; 134:jcs252726. [PMID: 33277382 DOI: 10.1242/jcs.252726] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/26/2020] [Indexed: 12/15/2022] Open
Abstract
Gap junctions have well-established roles in cell-cell communication by way of forming permeable intercellular channels. Less is understood about their internalization, which forms double membrane vesicles containing cytosol and membranes from another cell called connexosomes or annular gap junctions. Here, we systematically investigated the fate of connexosomes in intact ovarian follicles. High-pressure frozen, serial-sectioned tissue was immunogold labeled for connexin 43 (Cx43, also known as GJA1). Within a volume corresponding to ∼35 cells, every labeled structure was categorized and had its surface area measured. Measurements support the concept that multiple connexosomes form from larger invaginated gap junctions. Subsequently, the inner and outer membranes separate, Cx43 immunogenicity is lost from the outer membrane, and the inner membrane appears to undergo fission. One pathway for processing involves lysosomes, based on localization of cathepsin B to some processed connexosomes. In summary, this study demonstrates new technology for high-resolution analyses of gap junction processing.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Rachael P Norris
- Department of Cell Biology, UConn Health, 263 Farmington Ave, Farmington, CT 06030, USA
| | - Mark Terasaki
- Department of Cell Biology, UConn Health, 263 Farmington Ave, Farmington, CT 06030, USA
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11
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Hausenloy DJ, Schulz R, Girao H, Kwak BR, De Stefani D, Rizzuto R, Bernardi P, Di Lisa F. Mitochondrial ion channels as targets for cardioprotection. J Cell Mol Med 2020; 24:7102-7114. [PMID: 32490600 PMCID: PMC7339171 DOI: 10.1111/jcmm.15341] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/31/2020] [Accepted: 04/12/2020] [Indexed: 12/14/2022] Open
Abstract
Acute myocardial infarction (AMI) and the heart failure (HF) that often result remain the leading causes of death and disability worldwide. As such, new therapeutic targets need to be discovered to protect the myocardium against acute ischaemia/reperfusion (I/R) injury in order to reduce myocardial infarct (MI) size, preserve left ventricular function and prevent the onset of HF. Mitochondrial dysfunction during acute I/R injury is a critical determinant of cell death following AMI, and therefore, ion channels in the inner mitochondrial membrane, which are known to influence cell death and survival, provide potential therapeutic targets for cardioprotection. In this article, we review the role of mitochondrial ion channels, which are known to modulate susceptibility to acute myocardial I/R injury, and we explore their potential roles as therapeutic targets for reducing MI size and preventing HF following AMI.
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Affiliation(s)
- Derek J. Hausenloy
- Cardiovascular & Metabolic Disorders ProgramDuke‐National University of Singapore Medical SchoolSingaporeSingapore
- National Heart Research Institute SingaporeNational Heart CentreSingaporeSingapore
- Yong Loo Lin School of MedicineNational University SingaporeSingaporeSingapore
- The Hatter Cardiovascular InstituteUniversity College LondonLondonUK
- Cardiovascular Research CenterCollege of Medical and Health SciencesAsia UniversityTaichung CityTaiwan
| | - Rainer Schulz
- Institute of PhysiologyJustus‐Liebig University GiessenGiessenGermany
| | - Henrique Girao
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of MedicineUniversity of CoimbraCoimbraPortugal
- Center for Innovative Biomedicine and Biotechnology (CIBB)University of CoimbraCoimbraPortugal
- Clinical Academic Centre of CoimbraCACCCoimbraPortugal
| | - Brenda R. Kwak
- Department of Pathology and ImmunologyUniversity of GenevaGenevaSwitzerland
| | - Diego De Stefani
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
| | - Rosario Rizzuto
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
| | - Paolo Bernardi
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
- CNR Neuroscience InstitutePadovaItaly
| | - Fabio Di Lisa
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
- CNR Neuroscience InstitutePadovaItaly
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12
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Connexin/Innexin Channels in Cytoplasmic Organelles. Are There Intracellular Gap Junctions? A Hypothesis! Int J Mol Sci 2020; 21:ijms21062163. [PMID: 32245189 PMCID: PMC7139775 DOI: 10.3390/ijms21062163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/18/2020] [Accepted: 03/19/2020] [Indexed: 12/21/2022] Open
Abstract
This paper proposes the hypothesis that cytoplasmic organelles directly interact with each other and with gap junctions forming intracellular junctions. This hypothesis originated over four decades ago based on the observation that vesicles lining gap junctions of crayfish giant axons contain electron-opaque particles, similar in size to junctional innexons that often appear to directly interact with junctional innexons; similar particles were seen also in the outer membrane of crayfish mitochondria. Indeed, vertebrate connexins assembled into hexameric connexons are present not only in the membranes of the Golgi apparatus but also in those of the mitochondria and endoplasmic reticulum. It seems possible, therefore, that cytoplasmic organelles may be able to exchange small molecules with each other as well as with organelles of coupled cells via gap junctions.
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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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