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Héja L, Simon Á, Kardos J. Simulation of gap junction formation reveals critical role of Cys disulfide redox state in connexin hemichannel docking. Cell Commun Signal 2024; 22:185. [PMID: 38500186 PMCID: PMC10949817 DOI: 10.1186/s12964-023-01439-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 12/12/2023] [Indexed: 03/20/2024] Open
Abstract
Video Abstract.
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Affiliation(s)
- László Héja
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, 1117, Budapest, Hungary.
| | - Ágnes Simon
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, 1117, Budapest, Hungary
| | - Julianna Kardos
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, 1117, Budapest, Hungary
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2
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Lucaciu SA, Leighton SE, Hauser A, Yee R, Laird DW. Diversity in connexin biology. J Biol Chem 2023; 299:105263. [PMID: 37734551 PMCID: PMC10598745 DOI: 10.1016/j.jbc.2023.105263] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 09/08/2023] [Accepted: 09/14/2023] [Indexed: 09/23/2023] Open
Abstract
Over 35 years ago the cell biology community was introduced to connexins as the subunit employed to assemble semicrystalline clusters of intercellular channels that had been well described morphologically as gap junctions. The decade that followed would see knowledge of the unexpectedly large 21-member human connexin family grow to reflect unique and overlapping expression patterns in all organ systems. While connexin biology initially focused on their role in constructing highly regulated intercellular channels, this was destined to change as discoveries revealed that connexin hemichannels at the cell surface had novel roles in many cell types, especially when considering connexin pathologies. Acceptance of connexins as having bifunctional channel properties was initially met with some resistance, which has given way in recent years to the premise that connexins have multifunctional properties. Depending on the connexin isoform and cell of origin, connexins have wide-ranging half-lives that vary from a couple of hours to the life expectancy of the cell. Diversity in connexin channel characteristics and molecular properties were further revealed by X-ray crystallography and single-particle cryo-EM. New avenues have seen connexins or connexin fragments playing roles in cell adhesion, tunneling nanotubes, extracellular vesicles, mitochondrial membranes, transcription regulation, and in other emerging cellular functions. These discoveries were largely linked to Cx43, which is prominent in most human organs. Here, we will review the evolution of knowledge on connexin expression in human adults and more recent evidence linking connexins to a highly diverse array of cellular functions.
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Affiliation(s)
- Sergiu A Lucaciu
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Stephanie E Leighton
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Alexandra Hauser
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Ryan Yee
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
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3
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Qi C, Lavriha P, Bayraktar E, Vaithia A, Schuster D, Pannella M, Sala V, Picotti P, Bortolozzi M, Korkhov VM. Structures of wild-type and selected CMT1X mutant connexin 32 gap junction channels and hemichannels. SCIENCE ADVANCES 2023; 9:eadh4890. [PMID: 37647412 PMCID: PMC10468125 DOI: 10.1126/sciadv.adh4890] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 07/27/2023] [Indexed: 09/01/2023]
Abstract
In myelinating Schwann cells, connection between myelin layers is mediated by gap junction channels (GJCs) formed by docked connexin 32 (Cx32) hemichannels (HCs). Mutations in Cx32 cause the X-linked Charcot-Marie-Tooth disease (CMT1X), a degenerative neuropathy without a cure. A molecular link between Cx32 dysfunction and CMT1X pathogenesis is still missing. Here, we describe the high-resolution cryo-electron cryo-myography (cryo-EM) structures of the Cx32 GJC and HC, along with two CMT1X-linked mutants, W3S and R22G. While the structures of wild-type and mutant GJCs are virtually identical, the HCs show a major difference: In the W3S and R22G mutant HCs, the amino-terminal gating helix partially occludes the pore, consistent with a diminished HC activity. Our results suggest that HC dysfunction may be involved in the pathogenesis of CMT1X.
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Affiliation(s)
- Chao Qi
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Pia Lavriha
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Erva Bayraktar
- Veneto Institute of Molecular Medicine (VIMM), Padua, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Padua, Italy
| | - Anand Vaithia
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Dina Schuster
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
- Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Micaela Pannella
- Veneto Institute of Molecular Medicine (VIMM), Padua, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Padua, Italy
| | - Valentina Sala
- Veneto Institute of Molecular Medicine (VIMM), Padua, Italy
| | - Paola Picotti
- Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Mario Bortolozzi
- Veneto Institute of Molecular Medicine (VIMM), Padua, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Padua, Italy
| | - Volodymyr M. Korkhov
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
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4
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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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5
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Alsabbagh R, Ahmed M, Alqudah MAY, Hamoudi R, Harati R. Insights into the Molecular Mechanisms Mediating Extravasation in Brain Metastasis of Breast Cancer, Melanoma, and Lung Cancer. Cancers (Basel) 2023; 15:cancers15082258. [PMID: 37190188 DOI: 10.3390/cancers15082258] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/08/2023] [Accepted: 04/11/2023] [Indexed: 05/17/2023] Open
Abstract
Brain metastasis is an incurable end-stage of systemic cancer associated with poor prognosis, and its incidence is increasing. Brain metastasis occurs through a multi-step cascade where cancer cells spread from the primary tumor site to the brain. The extravasation of tumor cells through the blood-brain barrier (BBB) is a critical step in brain metastasis. During extravasation, circulating cancer cells roll along the brain endothelium (BE), adhere to it, then induce alterations in the endothelial barrier to transmigrate through the BBB and enter the brain. Rolling and adhesion are generally mediated by selectins and adhesion molecules induced by inflammatory mediators, while alterations in the endothelial barrier are mediated by proteolytic enzymes, including matrix metalloproteinase, and the transmigration step mediated by factors, including chemokines. However, the molecular mechanisms mediating extravasation are not yet fully understood. A better understanding of these mechanisms is essential as it may serve as the basis for the development of therapeutic strategies for the prevention or treatment of brain metastases. In this review, we summarize the molecular events that occur during the extravasation of cancer cells through the blood-brain barrier in three types of cancer most likely to develop brain metastasis: breast cancer, melanoma, and lung cancer. Common molecular mechanisms driving extravasation in these different tumors are discussed.
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Affiliation(s)
- Rama Alsabbagh
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah 27272, United Arab Emirates
- Research Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Munazza Ahmed
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah 27272, United Arab Emirates
- Research Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Mohammad A Y Alqudah
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah 27272, United Arab Emirates
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Rifat Hamoudi
- Clinical Sciences Department, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
- Division of Surgery and Interventional Science, University College London, London W1W 7EJ, UK
| | - Rania Harati
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah 27272, United Arab Emirates
- Research Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates
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6
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Lee SN, Cho HJ, Jeong H, Ryu B, Lee HJ, Kim M, Yoo J, Woo JS, Lee HH. Cryo-EM structures of human Cx36/GJD2 neuronal gap junction channel. Nat Commun 2023; 14:1347. [PMID: 36906653 PMCID: PMC10008584 DOI: 10.1038/s41467-023-37040-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 02/28/2023] [Indexed: 03/13/2023] Open
Abstract
Connexin 36 (Cx36) is responsible for signal transmission in electrical synapses by forming interneuronal gap junctions. Despite the critical role of Cx36 in normal brain function, the molecular architecture of the Cx36 gap junction channel (GJC) is unknown. Here, we determine cryo-electron microscopy structures of Cx36 GJC at 2.2-3.6 Å resolutions, revealing a dynamic equilibrium between its closed and open states. In the closed state, channel pores are obstructed by lipids, while N-terminal helices (NTHs) are excluded from the pore. In the open state with pore-lining NTHs, the pore is more acidic than those in Cx26 and Cx46/50 GJCs, explaining its strong cation selectivity. The conformational change during channel opening also includes the α-to-π-helix transition of the first transmembrane helix, which weakens the protomer-protomer interaction. Our structural analyses provide high resolution information on the conformational flexibility of Cx36 GJC and suggest a potential role of lipids in the channel gating.
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Affiliation(s)
- Seu-Na Lee
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Hwa-Jin Cho
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Hyeongseop Jeong
- Center for Research Equipment, Korea Basic Science Institute, Chungcheongbuk-do, 28119, Korea
| | - Bumhan Ryu
- Research Solution Center, Institute for Basic Science, Daejeon, 34126, Republic of Korea
| | - Hyuk-Joon Lee
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Minsoo Kim
- Department of Physics, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Jae-Sung Woo
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea.
| | - Hyung Ho Lee
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea.
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7
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Field carcinogenesis and biological significance of the potential of the bystander effect: carcinogenesis, therapeutic response, and tissue regeneration. Surg Today 2022; 53:545-553. [PMID: 35576018 DOI: 10.1007/s00595-022-02524-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 03/30/2022] [Indexed: 10/18/2022]
Abstract
The "bystander effect" is a transmission phenomenon mediating communication from target to non-target cells, as well as cell-to-cell interactions between neighboring and distantly located cells. In this narrative review, we describe the fundamental and clinical significance of the bystander effect with respect to cell-to-cell interactions in carcinogenesis, therapeutic response, and tissue regeneration. In carcinogenesis, the bystander effect mediates communications between tumor microenvironments and non-malignant epithelial cells and has been suggested to impact heterogeneous tumorigenic cells in tumors and cancerized fields. In therapeutic response, the bystander effect mediates communications between drug-sensitive and drug-resistant cells and may transmit both drug efficacy and resistance. Therefore, control of therapeutic response transmission via the bystander effect might offer a promising future cancer treatment. Finally, in tissue regeneration, circulating cells and stromal cells may differentiate into various cells for the purpose of tissue regeneration under direction of the bystander effect arising from surrounding cells in a defective space. We hope that the findings we present will promote the development of innovative cancer therapies and tissue regeneration methodologies from the viewpoint of cell-to-cell interactions through the bystander effect.
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8
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Brotherton DH, Savva CG, Ragan TJ, Dale N, Cameron AD. Conformational changes and CO 2-induced channel gating in connexin26. Structure 2022; 30:697-706.e4. [PMID: 35276081 PMCID: PMC9592558 DOI: 10.1016/j.str.2022.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 01/24/2022] [Accepted: 02/14/2022] [Indexed: 12/22/2022]
Abstract
Connexins form large-pore channels that function either as dodecameric gap junctions or hexameric hemichannels to allow the regulated movement of small molecules and ions across cell membranes. Opening or closing of the channels is controlled by a variety of stimuli, and dysregulation leads to multiple diseases. An increase in the partial pressure of carbon dioxide (PCO2) has been shown to cause connexin26 (Cx26) gap junctions to close. Here, we use cryoelectron microscopy (cryo-EM) to determine the structure of human Cx26 gap junctions under increasing levels of PCO2. We show a correlation between the level of PCO2 and the size of the aperture of the pore, governed by the N-terminal helices that line the pore. This indicates that CO2 alone is sufficient to cause conformational changes in the protein. Analysis of the conformational states shows that movements at the N terminus are linked to both subunit rotation and flexing of the transmembrane helices. High-resolution cryo-EM structures of connexin26 at varying levels of PCO2 CO2 alone causes conformational changes in the protein under stable pH conditions The N-terminal helices regulate the aperture of the pore KID syndrome mutations affecting CO2 sensitivity map to flexion points of structure
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Affiliation(s)
- Deborah H Brotherton
- School of Life Sciences, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, UK
| | - Christos G Savva
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Lancaster Road, LE1 7HB Leicester, UK
| | - Timothy J Ragan
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Lancaster Road, LE1 7HB Leicester, UK
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, UK.
| | - Alexander D Cameron
- School of Life Sciences, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, UK.
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Gap Junction-Dependent and -Independent Functions of Connexin43 in Biology. BIOLOGY 2022; 11:biology11020283. [PMID: 35205149 PMCID: PMC8869330 DOI: 10.3390/biology11020283] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 12/21/2022]
Abstract
For the first time in animal evolution, the emergence of gap junctions allowed direct exchanges of cellular substances for communication between two cells. Innexin proteins constituted primordial gap junctions until the connexin protein emerged in deuterostomes and took over the gap junction function. After hundreds of millions of years of gene duplication, the connexin gene family now comprises 21 members in the human genome. Notably, GJA1, which encodes the Connexin43 protein, is one of the most widely expressed and commonly studied connexin genes. The loss of Gja1 in mice leads to swelling and a blockage of the right ventricular outflow tract and death of the embryos at birth, suggesting a vital role of Connexin43 gap junction in heart development. Since then, the importance of Connexin43-mediated gap junction function has been constantly expanded to other types of cells. Other than forming gap junctions, Connexin43 can also form hemichannels to release or uptake small molecules from the environment or even mediate many physiological processes in a gap junction-independent manner on plasma membranes. Surprisingly, Connexin43 also localizes to mitochondria in the cell, playing important roles in mitochondrial potassium import and respiration. At the molecular level, Connexin43 mRNA and protein are processed with very distinct mechanisms to yield carboxyl-terminal fragments with different sizes, which have their unique subcellular localization and distinct biological activities. Due to many exciting advancements in Connexin43 research, this review aims to start with a brief introduction of Connexin43 and then focuses on updating our knowledge of its gap junction-independent functions.
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Kuwano H, Yokobori T, Ide M, Saeki H, Sohda M, Sakai M, Yoshida T, Kuriyama K, Ogata K, Ogawa H, Okada T, Miyazaki T, Takahashi S, Shirabe K. Coexistence of superficial carcinogenesis of resident epithelium besides neuroendocrine neoplasm of the digestive tract. Cancer Med 2022; 11:983-992. [PMID: 35048546 PMCID: PMC8855898 DOI: 10.1002/cam4.4485] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 09/05/2021] [Accepted: 09/11/2021] [Indexed: 01/05/2023] Open
Abstract
Background & Aims Mixed neuroendocrine–non‐neuroendocrine neoplasm (MiNEN) is a rare neuroendocrine neoplasm (NEN) comprising dual neuroendocrine and non‐neuroendocrine components. Although the coexistence pattern of neuroendocrine and non‐neuroendocrine components in definitive MiNEN is thought to overlap, there may be a coexistent pattern of both components, such as superficial carcinoma adjacent to NEN. The present study evaluated the histopathological findings of the coexistence pattern of superficial carcinomas adjacent to NENs in the esophagogastrointestinal tract. Methods From 2000 to 2019, 35 serial NEN resections of the esophagus (n = 9), stomach (n = 3), and large intestine (n = 23), respectively, were performed at Gunma University Hospital. Borderline areas between NEN and resident superficial epithelium were observed in the 35 serial NEN cases as well as two additional cases from affiliated hospitals. Results Among the 35 serial NEN samples, squamous cell carcinomatous/dysplastic components were identified 77.8% (7/9 cases) of esophageal NENs, and adenocarcinomatous areas were seen in 66.7% (2/3 cases) of gastric NENs and 26% (6/23 cases) of colorectal NENs. Thus, all superficial carcinomatous components adjacent to NENs were observed as squamous cell carcinoma/dysplasia in esophagus and adenocarcinoma in stomach and large intestine, which showed histological characteristics as the resident epithelial pattern in each organ. Conclusions These findings suggested a potential “paratransformation” or “bystander effect” in resident epithelium by NENs. Thus, “bystander carcinogenesis” could be a pathogenic mechanism of resident epithelium transformation adjacent to NENs in the esophagogastrointestinal tract.
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Affiliation(s)
- Hiroyuki Kuwano
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan.,Fukuoka City Hospital, Fukuoka, Japan
| | - Takehiko Yokobori
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan.,Division of Integrated Oncology Research, Gunma University Initiative for Advanced Research (GIAR), Maebashi, Japan
| | - Munenori Ide
- Department of Pathology, Maebashi Red Cross Hospital, Maebashi, Japan
| | - Hiroshi Saeki
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Makoto Sohda
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Makoto Sakai
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Tomonori Yoshida
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Kengo Kuriyama
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Kyoichi Ogata
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Hiroomi Ogawa
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takuhisa Okada
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Tatsuya Miyazaki
- Department of Surgery, Maebashi Red Cross Hospital, Maebashi, Japan
| | | | - Ken Shirabe
- Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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González-Casanova JE, Durán-Agüero S, Caro-Fuentes NJ, Gamboa-Arancibia ME, Bruna T, Bermúdez V, Rojas-Gómez DM. New Insights on the Role of Connexins and Gap Junctions Channels in Adipose Tissue and Obesity. Int J Mol Sci 2021; 22:ijms222212145. [PMID: 34830025 PMCID: PMC8619175 DOI: 10.3390/ijms222212145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/05/2021] [Accepted: 11/05/2021] [Indexed: 12/20/2022] Open
Abstract
Due to the inability to curb the excessive increase in the prevalence of obesity and overweight, it is necessary to comprehend in more detail the factors involved in the pathophysiology and to appreciate more clearly the biochemical and molecular mechanisms of obesity. Thus, understanding the biological regulation of adipose tissue is of fundamental relevance. Connexin, a protein that forms intercellular membrane channels of gap junctions and unopposed hemichannels, plays a key role in adipogenesis and in the maintenance of adipose tissue homeostasis. The expression and function of Connexin 43 (Cx43) during the different stages of the adipogenesis are differentially regulated. Moreover, it has been shown that cell–cell communication decreases dramatically upon differentiation into adipocytes. Furthermore, inhibition of Cx43 degradation or constitutive overexpression of Cx43 blocks adipocyte differentiation. In the first events of adipogenesis, the connexin is highly phosphorylated, which is likely associated with enhanced Gap Junction (GJ) communication. In an intermediate state of adipocyte differentiation, Cx43 phosphorylation decreases, as it is displaced from the membrane and degraded through the proteasome; thus, Cx43 total protein is reduced. Cx is involved in cardiac disease as well as in obesity-related cardiovascular diseases. Different studies suggest that obesity together with a high-fat diet are related to the production of remodeling factors associated with expression and distribution of Cx43 in the atrium.
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Affiliation(s)
- Jorge Enrique González-Casanova
- Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago 8910060, Chile; (J.E.G.-C.); (N.J.C.-F.)
| | - Samuel Durán-Agüero
- Facultad de Ciencias Para el Cuidado de la Salud, Universidad San Sebastián, Sede Los Leones, Lota 2465, Providencia, Santiago 7500000, Chile;
| | - Nelson Javier Caro-Fuentes
- Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago 8910060, Chile; (J.E.G.-C.); (N.J.C.-F.)
| | - Maria Elena Gamboa-Arancibia
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O’higgins 3363, Estación Central, Santiago 9170022, Chile;
| | - Tamara Bruna
- Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomás, Avenida Ejercito 146, Santiago 8320000, Chile;
| | - Valmore Bermúdez
- Facultad de Ciencias de la Salud, Universidad Simón Bolívar, Barranquilla 080002, Colombia;
| | - Diana Marcela Rojas-Gómez
- Escuela de Nutrición y Dietética, Facultad de Medicina, Universidad Andres Bello, Santiago 8370321, Chile
- Correspondence: ; Tel.: +56-226618559
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12
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Giridharan N, Glitza Oliva IC, O'Brien BJ, Parker Kerrigan BC, Heimberger AB, Ferguson SD. Targeting the Tumor Microenvironment in Brain Metastasis. Neurosurg Clin N Am 2021; 31:641-649. [PMID: 32921358 DOI: 10.1016/j.nec.2020.06.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dynamic interplay between cancer cells and the surrounding microenvironment is a feature of the metastatic process. Successful metastatic brain colonization requires complex mechanisms that ultimately allow tumor cells to adapt to the unique microenvironment of the central nervous system, evade immune destruction, survive, and grow. Accumulating evidence suggests that components of the brain tumor microenvironment (TME) play a vital role in the metastatic cascade. In this review, the authors summarize the contribution of the TME to the development and progression of brain metastasis. They also highlight opportunities for TME-directed targeted therapy.
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Affiliation(s)
- Nisha Giridharan
- Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 422, Houston, TX 77030, USA
| | - Isabella C Glitza Oliva
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 430, Houston, TX 77030, USA
| | - Barbara J O'Brien
- Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 431, Houston, TX 77030-4009, USA
| | - Brittany C Parker Kerrigan
- Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 422, Houston, TX 77030, USA
| | - Amy B Heimberger
- Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 422, Houston, TX 77030, USA
| | - Sherise D Ferguson
- Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 422, Houston, TX 77030, USA.
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13
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Zhang K, Guan QW, Zhou XY, Xia QX, Yin XX, Zhou HH, Mao XY. The mutual interplay of redox signaling and connexins. J Mol Med (Berl) 2021; 99:933-941. [PMID: 33928434 DOI: 10.1007/s00109-021-02084-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/20/2021] [Accepted: 04/26/2021] [Indexed: 11/24/2022]
Abstract
Connexins (Cxs) are ubiquitous transmembrane proteins that possess both channel function (e.g., formations of gap junction and hemichannel) and non-channel properties (e.g., gene transcription and protein-protein interaction). Several factors have been identified to play a role in the regulation of Cxs, which include those acting intracellularly, as redox potential, pH, intramolecular interactions, and post-translational modifications (e.g., phosphorylation, S-nitrosylation) as well as those acting extracellularly, such as Ca2+ and Mg2+. The relationship between redox signaling and Cxs attracts considerable attention in recent years. There is ample evidence showing that redox signaling molecules (e.g., hydrogen peroxide (H2O2), nitric oxide (NO)) affect Cxs-based channel function while the opening of Cx channels also triggers the transfer of various redox-related metabolites (e.g., reactive oxygen species, glutathione, nicotinamide adenine dinucleotide, and NO). On the basis of these evidences, we propose the existence of redox-Cxs crosstalk. In this review, we briefly discuss the interaction between redox signaling and Cxs and the implications of the intersection in disease pathology and future therapeutic interventions.
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Affiliation(s)
- Kai Zhang
- Department of Clinical Pharmacology, Xiangya Hospital and Institute of Clinical Pharmacology, Central South University, 87 Xiangya Road, Changsha, 410008, People's Republic of China.,Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, 87 Xiangya Road, Changsha, 410008, Hunan, People's Republic of China
| | - Qi-Wen Guan
- Department of Clinical Pharmacology, Xiangya Hospital and Institute of Clinical Pharmacology, Central South University, 87 Xiangya Road, Changsha, 410008, People's Republic of China.,Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, 87 Xiangya Road, Changsha, 410008, Hunan, People's Republic of China
| | - Xin-Yu Zhou
- Department of Neurology, Lianyungang Hospital affiliated with Xuzhou Medical College, Tongguan Road, 182, Lianyungang, Jiangsu, People's Republic of China
| | - Qin-Xuan Xia
- Department of Clinical Pharmacology, Xiangya Hospital and Institute of Clinical Pharmacology, Central South University, 87 Xiangya Road, Changsha, 410008, People's Republic of China.,Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, 87 Xiangya Road, Changsha, 410008, Hunan, People's Republic of China
| | - Xi-Xi Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410008, Hunan, People's Republic of China
| | - Hong-Hao Zhou
- Department of Clinical Pharmacology, Xiangya Hospital and Institute of Clinical Pharmacology, Central South University, 87 Xiangya Road, Changsha, 410008, People's Republic of China.,Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, 110 Xiangya Road, Changsha, 410078, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, 87 Xiangya Road, Changsha, 410008, Hunan, People's Republic of China
| | - Xiao-Yuan Mao
- Department of Clinical Pharmacology, Xiangya Hospital and Institute of Clinical Pharmacology, Central South University, 87 Xiangya Road, Changsha, 410008, People's Republic of China. .,Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, 110 Xiangya Road, Changsha, 410078, People's Republic of China. .,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, 110 Xiangya Road, Changsha, 410078, People's Republic of China. .,National Clinical Research Center for Geriatric Disorders, 87 Xiangya Road, Changsha, 410008, Hunan, People's Republic of China.
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14
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Okamoto T, Park EJ, Kawamoto E, Usuda H, Wada K, Taguchi A, Shimaoka M. Endothelial connexin-integrin crosstalk in vascular inflammation. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166168. [PMID: 33991620 DOI: 10.1016/j.bbadis.2021.166168] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/18/2021] [Accepted: 05/02/2021] [Indexed: 02/06/2023]
Abstract
Cardiovascular diseases including blood vessel disorders represent a major cause of death globally. The essential roles played by local and systemic vascular inflammation in the pathogenesis of cardiovascular diseases have been increasingly recognized. Vascular inflammation triggers the aberrant activation of endothelial cells, which leads to the functional and structural abnormalities in vascular vessels. In addition to humoral mediators such as pro-inflammatory cytokines and prostaglandins, the alteration of physical and mechanical microenvironment - including vascular stiffness and shear stress - modify the gene expression profiles and metabolic profiles of endothelial cells via mechano-transduction pathways, thereby contributing to the pathogenesis of vessel disorders. Notably, connexins and integrins crosstalk each other in response to the mechanical stress, and, thereby, play an important role in regulating the mechano-transduction of endothelial cells. Here, we provide an overview on how the inter-play between connexins and integrins in endothelial cells unfold during the mechano-transduction in vascular inflammation.
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Affiliation(s)
- Takayuki Okamoto
- Department of Pharmacology, Faculty of Medicine, Shimane University, 89-1 Enya-cho, Izumo-city, Shimane 693-8501, Japan.
| | - Eun Jeong Park
- Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu-city, Mie 514-8507, Japan
| | - Eiji Kawamoto
- Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu-city, Mie 514-8507, Japan; Department of Emergency and Disaster Medicine, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu-city, Mie 514-8507, Japan
| | - Haruki Usuda
- Department of Pharmacology, Faculty of Medicine, Shimane University, 89-1 Enya-cho, Izumo-city, Shimane 693-8501, Japan
| | - Koichiro Wada
- Department of Pharmacology, Faculty of Medicine, Shimane University, 89-1 Enya-cho, Izumo-city, Shimane 693-8501, Japan
| | - Akihiko Taguchi
- Department of Regenerative Medicine Research, Foundation for Biomedical Research and Innovation at Kobe, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Motomu Shimaoka
- Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu-city, Mie 514-8507, Japan.
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15
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Ugwu N, Atzmony L, Ellis KT, Panse G, Jain D, Ko CJ, Nassiri N, Choate KA. Cutaneous and hepatic vascular lesions due to a recurrent somatic GJA4 mutation reveal a pathway for vascular malformation. HGG ADVANCES 2021; 2. [PMID: 33912852 PMCID: PMC8078848 DOI: 10.1016/j.xhgg.2021.100028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The term “cavernous hemangioma” has been used to describe vascular anomalies with histology featuring dilated vascular spaces, vessel walls consisting mainly of fibrous stromal bands lined by a layer of flattened endothelial cells, and an irregular outer rim of interrupted smooth muscle cells. Hepatic hemangiomas (HHs) and cutaneous venous malformations (VMs) share this histologic pattern, and we examined lesions in both tissues to identify genetic drivers. Paired whole-exome sequencing (WES) of lesional tissue and normal liver in HH subjects revealed a recurrent GJA4 c.121G>T (p.Gly41Cys) somatic mutation in four of five unrelated individuals, and targeted sequencing in paired tissue from 9 additional HH individuals identified the same mutation in 8. In cutaneous lesions, paired targeted sequencing in 5 VMs and normal epidermis found the same GJA4 c.121G>T (p.Gly41Cys) somatic mutation in three. GJA4 encodes gap junction protein alpha 4, also called connexin 37 (Cx37), and the p.Gly41Cys mutation falls within the first transmembrane domain at a residue highly conserved among vertebrates. We interrogated the impact of the Cx37 mutant via lentiviral transduction of primary human endothelial cells. We found that the mutant induced changes in cell morphology and activated serum/glucocorticoid-regulated kinase 1 (SGK1), a serine/threonine kinase known to regulate cell proliferation and apoptosis, via non-canonical activation. Treatment with spironolactone, an inhibitor of angiogenesis, suppressed mutant SGK1 activation and reversed changes in cell morphology. These findings identify a recurrent somatic GJA4 c.121G>T mutation as a driver of hepatic and cutaneous VMs, revealing a new pathway for vascular anomalies, with spironolactone a potential pathogenesis-based therapy.
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Affiliation(s)
- Nelson Ugwu
- Department of Dermatology, School of Medicine, Yale University, New Haven, CT 06510, USA.,Vascular Malformations Program (VaMP), Yale New Haven Hospital, New Haven, CT, USA
| | - Lihi Atzmony
- Department of Dermatology, School of Medicine, Yale University, New Haven, CT 06510, USA.,Department of Genetics, Yale University School of Medicine, New Haven, CT, USA.,Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Vascular Malformations Program (VaMP), Yale New Haven Hospital, New Haven, CT, USA
| | - Katharine T Ellis
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Gauri Panse
- Department of Dermatology, School of Medicine, Yale University, New Haven, CT 06510, USA.,Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Vascular Malformations Program (VaMP), Yale New Haven Hospital, New Haven, CT, USA
| | - Dhanpat Jain
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Christine J Ko
- Department of Dermatology, School of Medicine, Yale University, New Haven, CT 06510, USA.,Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Vascular Malformations Program (VaMP), Yale New Haven Hospital, New Haven, CT, USA
| | - Naiem Nassiri
- Division of Vascular and Endovascular Surgery, Department of Surgery, Yale University School of Medicine, New Haven, CT 06510, USA.,Vascular Malformations Program (VaMP), Yale New Haven Hospital, New Haven, CT, USA.,Senior author
| | - Keith A Choate
- Department of Dermatology, School of Medicine, Yale University, New Haven, CT 06510, USA.,Department of Genetics, Yale University School of Medicine, New Haven, CT, USA.,Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Vascular Malformations Program (VaMP), Yale New Haven Hospital, New Haven, CT, USA.,Senior author
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16
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The role of connexin proteins and their channels in radiation-induced atherosclerosis. Cell Mol Life Sci 2021; 78:3087-3103. [PMID: 33388835 PMCID: PMC8038956 DOI: 10.1007/s00018-020-03716-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/29/2020] [Accepted: 11/17/2020] [Indexed: 02/08/2023]
Abstract
Radiotherapy is an effective treatment for breast cancer and other thoracic tumors. However, while high-energy radiotherapy treatment successfully kills cancer cells, radiation exposure of the heart and large arteries cannot always be avoided, resulting in secondary cardiovascular disease in cancer survivors. Radiation-induced changes in the cardiac vasculature may thereby lead to coronary artery atherosclerosis, which is a major cardiovascular complication nowadays in thoracic radiotherapy-treated patients. The underlying biological and molecular mechanisms of radiation-induced atherosclerosis are complex and still not fully understood, resulting in potentially improper radiation protection. Ionizing radiation (IR) exposure may damage the vascular endothelium by inducing DNA damage, oxidative stress, premature cellular senescence, cell death and inflammation, which act to promote the atherosclerotic process. Intercellular communication mediated by connexin (Cx)-based gap junctions and hemichannels may modulate IR-induced responses and thereby the atherosclerotic process. However, the role of endothelial Cxs and their channels in atherosclerotic development after IR exposure is still poorly defined. A better understanding of the underlying biological pathways involved in secondary cardiovascular toxicity after radiotherapy would facilitate the development of effective strategies that prevent or mitigate these adverse effects. Here, we review the possible roles of intercellular Cx driven signaling and communication in radiation-induced atherosclerosis.
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17
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Antagonistic Functions of Connexin 43 during the Development of Primary or Secondary Bone Tumors. Biomolecules 2020; 10:biom10091240. [PMID: 32859065 PMCID: PMC7565206 DOI: 10.3390/biom10091240] [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: 07/21/2020] [Revised: 08/20/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022] Open
Abstract
Despite research and clinical advances during recent decades, bone cancers remain a leading cause of death worldwide. There is a low survival rate for patients with primary bone tumors such as osteosarcoma and Ewing’s sarcoma or secondary bone tumors such as bone metastases from prostate carcinoma. Gap junctions are specialized plasma membrane structures consisting of transmembrane channels that directly link the cytoplasm of adjacent cells, thereby enabling the direct exchange of small signaling molecules between cells. Discoveries of human genetic disorders due to genetic mutations in gap junction proteins (connexins) and experimental data using connexin knockout mice have provided significant evidence that gap-junctional intercellular communication (Gj) is crucial for tissue function. Thus, the dysfunction of Gj may be responsible for the development of some diseases. Gj is thus a main mechanism for tumor cells to communicate with other tumor cells and their surrounding microenvironment to survive and proliferate. If it is well accepted that a low level of connexin expression favors cancer cell proliferation and therefore primary tumor development, more evidence is suggesting that a high level of connexin expression stimulates various cellular process such as intravasation, extravasation, or migration of metastatic cells. If so, connexin expression would facilitate secondary tumor dissemination. This paper discusses evidence that suggests that connexin 43 plays an antagonistic role in the development of primary bone tumors as a tumor suppressor and secondary bone tumors as a tumor promoter.
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18
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Lee HJ, Jeong H, Hyun J, Ryu B, Park K, Lim HH, Yoo J, Woo JS. Cryo-EM structure of human Cx31.3/GJC3 connexin hemichannel. SCIENCE ADVANCES 2020; 6:eaba4996. [PMID: 32923625 PMCID: PMC7455182 DOI: 10.1126/sciadv.aba4996] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 07/15/2020] [Indexed: 05/28/2023]
Abstract
Connexin family proteins assemble into hexameric channels called hemichannels/connexons, which function as transmembrane channels or dock together to form gap junction intercellular channels (GJIChs). We determined the cryo-electron microscopy structures of human connexin 31.3 (Cx31.3)/GJC3 hemichannels in the presence and absence of calcium ions and with a hearing-loss mutation R15G at 2.3-, 2.5-, and 2.6-Å resolutions, respectively. Compared with available structures of GJICh in open conformation, Cx31.3 hemichannel shows substantial structural changes of highly conserved regions in the connexin family, including opening of calcium ion-binding tunnels, reorganization of salt-bridge networks, exposure of lipid-binding sites, and collocation of amino-terminal helices at the cytoplasmic entrance. We also found that the hemichannel has a pore with a diameter of ~8 Å and selectively transports chloride ions. Our study provides structural insights into the permeant selectivity of Cx31.3 hemichannel.
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Affiliation(s)
- Hyuk-Joon Lee
- Department of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Hyeongseop Jeong
- Department of Life Sciences, Korea University, Seoul 02841, Republic of Korea
- Korea Basic Science Institute, Chungcheongbuk-do 28119, Republic of Korea
| | - Jaekyung Hyun
- Korea Basic Science Institute, Chungcheongbuk-do 28119, Republic of Korea
- Molecular Cryo-electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0496, Japan
| | - Bumhan Ryu
- Department of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Kunwoong Park
- Neurovascular Unit Research Group, Korea Brain Research Institute (KBRI), 41062 Daegu, Republic of Korea
| | - Hyun-Ho Lim
- Neurovascular Unit Research Group, Korea Brain Research Institute (KBRI), 41062 Daegu, Republic of Korea
| | - Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Jae-Sung Woo
- Department of Life Sciences, Korea University, Seoul 02841, Republic of Korea
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19
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Mitochondrial F-ATP synthase as the permeability transition pore. Pharmacol Res 2020; 160:105081. [PMID: 32679179 DOI: 10.1016/j.phrs.2020.105081] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 07/06/2020] [Accepted: 07/10/2020] [Indexed: 12/27/2022]
Abstract
The current state of research on the mitochondrial permeability transition pore (PTP) can be described in terms of three major problems: molecular identity, atomic structure and gating mechanism. In this review these three problems are discussed in the light of recent findings with special emphasis on the discovery that the PTP is mitochondrial F-ATP synthase (mtFoF1). Novel features of the mitochondrial F-ATP synthase emerging from the success of single particle cryo electron microscopy (cryo-EM) to determine F-ATP synthase structures are surveyed along with their possible involvement in pore formation. Also, current findings from the gap junction field concerning the involvement of lipids in channel closure are examined. Finally, an earlier proposal denoted as the 'Death Finger' is discussed as a working model for PTP gating.
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20
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Abstract
Of the 21 members of the connexin family, 4 (Cx37, Cx40, Cx43, and Cx45) are expressed in the endothelium and/or smooth muscle of intact blood vessels to a variable and dynamically regulated degree. Full-length connexins oligomerize and form channel structures connecting the cytosol of adjacent cells (gap junctions) or the cytosol with the extracellular space (hemichannels). The different connexins vary mainly with regard to length and sequence of their cytosolic COOH-terminal tails. These COOH-terminal parts, which in the case of Cx43 are also translated as independent short isoforms, are involved in various cellular signaling cascades and regulate cell functions. This review focuses on channel-dependent and -independent effects of connexins in vascular cells. Channels play an essential role in coordinating and synchronizing endothelial and smooth muscle activity and in their interplay, in the control of vasomotor actions of blood vessels including endothelial cell reactivity to agonist stimulation, nitric oxide-dependent dilation, and endothelial-derived hyperpolarizing factor-type responses. Further channel-dependent and -independent roles of connexins in blood vessel function range from basic processes of vascular remodeling and angiogenesis to vascular permeability and interactions with leukocytes with the vessel wall. Together, these connexin functions constitute an often underestimated basis for the enormous plasticity of vascular morphology and function enabling the required dynamic adaptation of the vascular system to varying tissue demands.
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Affiliation(s)
- Ulrich Pohl
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany; Biomedical Centre, Cardiovascular Physiology, LMU Munich, Planegg-Martinsried, Germany; German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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21
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Structural insights into gap junction channels boosted by cryo-EM. Curr Opin Struct Biol 2020; 63:42-48. [PMID: 32339861 DOI: 10.1016/j.sbi.2020.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/15/2020] [Accepted: 03/15/2020] [Indexed: 11/23/2022]
Abstract
Regulating intercellular communication is essential for multicellular organisms. Gap junction channels are the major components mediating this function, but the molecular mechanisms underlying their opening and closing remain unclear. Single-particle cryo-electron microscopy (cryo-EM) is a powerful tool for investigating high-resolution protein structures that are difficult to crystallize, such as gap junction channels. Membrane protein structures are often determined in a detergent solubilized form, but lipid bilayers provide a near native environment for structural analysis. This review focuses on recent reports of gap junction channel structures visualized by cryo-EM. An overview of the differences observed in gap junction channel structures in the presence and absence of lipids is described, which may contribute to elucidating the regulation mechanisms of gap junction channel function.
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22
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Sinha G, Ferrer AI, Moore CA, Naaldijk Y, Rameshwar P. Gap Junctions and Breast Cancer Dormancy. Trends Cancer 2020; 6:348-357. [PMID: 32209448 DOI: 10.1016/j.trecan.2020.01.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 01/22/2020] [Accepted: 01/23/2020] [Indexed: 12/21/2022]
Abstract
Breast cancer (BC) relapse, despite clinical advancement, remains one of the biggest issues in the field. Intercellular communication, specifically via connexin (Cx)-mediated gap junctions (GJs), play a key role in the long-term survival of these, treatment-resistant breast cancer stem cells (CSCs), allowing for relapse. Both basic and clinical evidence reveal dual roles for GJs, in tumor suppression, generally referred to as dormancy, and progression and metastasis. GJ intercellular communication (GJIC) can be mediated by multiple types of Cxs, depending on the organ to which the BC cells metastasize. This review expands on the differential expression of Cx-mediated GJIC between CSCs and niche cells within a given microenvironment.
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Affiliation(s)
- Garima Sinha
- Rutgers School of Graduate Studies at New Jersey Medical School, Newark, NJ, USA; Department of Medicine - Hematology/Oncology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Alejandra I Ferrer
- Rutgers School of Graduate Studies at New Jersey Medical School, Newark, NJ, USA; Department of Medicine - Hematology/Oncology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Caitlyn A Moore
- Rutgers School of Graduate Studies at New Jersey Medical School, Newark, NJ, USA; Department of Medicine - Hematology/Oncology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Yahaira Naaldijk
- Rutgers School of Graduate Studies at New Jersey Medical School, Newark, NJ, USA
| | - Pranela Rameshwar
- Department of Medicine - Hematology/Oncology, Rutgers New Jersey Medical School, Newark, NJ, USA.
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23
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Cancer exosomal microRNAs from gefitinib-resistant lung cancer cells cause therapeutic resistance in gefitinib-sensitive cells. Surg Today 2020; 50:1099-1106. [PMID: 32052182 DOI: 10.1007/s00595-020-01976-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 01/28/2020] [Indexed: 12/13/2022]
Abstract
PURPOSE Exosomes and their cargo microRNAs play a significant role in various biological processes in cancer. We hypothesized that microRNAs in exosomes secreted by gefitinib-resistant lung cancer cells might induce resistant phenotypes in otherwise gefitinib-sensitive lung cancer cells. METHODS We isolated exosomes generated by the gefitinib-resistant human lung adenocarcinoma cell line PS-9/ZD. PC-9, which is a gefitinib-sensitive cell line, was treated with the PC-9/ZD exosomes, and these PC-9 cells were analyzed for cell proliferation after treatment with gefitinib. miRNA arrays were analyzed in PC-9 and PC-9/ZD cells, and we isolated microRNAs that were expressed at elevated levels in PC-9/ZD cells. Furthermore, we transfected these microRNAs into PC-9 cells and analyzed the effects on the cells' sensitivity to gefitinib. RESULTS Exosomes isolated from PC-9/ZD cells significantly increased the proliferation of PC-9 cells during gefitinib treatment. A microRNA array analysis showed that miR-564, miR-658, miR-3652, miR-3126-5p, miR-3682-3p and miR-6810-5p were significantly upregulated in PC-9/ZD cells. PC-9 cells transfected with miR-564 or miR-658 showed chemo-resistant phenotypes. CONCLUSION Exosomal miR-564 and miR-658 derived from gefitinib-resistant lung cancer cells induce drug resistance in sensitive cells. Cell-to-cell interaction via exosomal microRNAs may be a novel mechanism and therapeutic target of resistance against gefitinib.
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24
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Burendei B, Shinozaki R, Watanabe M, Terada T, Tani K, Fujiyoshi Y, Oshima A. Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids. SCIENCE ADVANCES 2020; 6:eaax3157. [PMID: 32095518 PMCID: PMC7015682 DOI: 10.1126/sciadv.aax3157] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 12/02/2019] [Indexed: 06/01/2023]
Abstract
Gap junctions form intercellular conduits with a large pore size whose closed and open states regulate communication between adjacent cells. The structural basis of the mechanism by which gap junctions close, however, remains uncertain. Here, we show the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction proteins in an undocked hemichannel form. In the nanodisc-reconstituted structure of the wild-type INX-6 hemichannel, flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted amino-terminal deletion mutant reveals that lipid-mediated amino-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution. Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into the closure of the INX-6 hemichannel in a lipid bilayer before docking of two hemichannels.
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Affiliation(s)
- Batuujin Burendei
- Division of Biological Science, School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Ruriko Shinozaki
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tohru Terada
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- CeSPIA Inc., Ōtemachi, Chiyoda, Tokyo 100-0004, Japan
| | - Atsunori Oshima
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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25
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Price GW, Potter JA, Williams BM, Cliff CL, Squires PE, Hills CE. Connexin-mediated cell communication in the kidney: A potential therapeutic target for future intervention of diabetic kidney disease?: Joan Mott Prize Lecture. Exp Physiol 2020; 105:219-229. [PMID: 31785013 DOI: 10.1113/ep087770] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/19/2019] [Indexed: 12/21/2022]
Abstract
The ability of cells to communicate and synchronise their activity is essential for the maintenance of tissue structure, integrity and function. A family of membrane-bound proteins called connexins are largely responsible for mediating the local transfer of information between cells. Assembled in the cell membrane as a hexameric connexon, they either function as a conduit for paracrine signalling, forming a transmembrane hemi-channel, or, if aligned with connexons on neighbouring cells, form a continuous aqueous pore or gap junction, which allows for the direct transmission of metabolic and electrical signals. Regulation of connexin synthesis and activity is critical to cellular function, and a number of diseases are attributed to changes in the expression and/or function of these important proteins. A link between hyperglycaemia, connexin expression, altered nucleotide concentrations and impaired function highlights a potential role for connexin-mediated cell communication in complications of diabetes. In the diabetic kidney, glycaemic injury is the leading cause of end-stage renal failure, reflecting multiple aetiologies including glomerular hyperfiltration, albuminuria, increased deposition of extracellular matrix and tubulointerstitial fibrosis. Loss of connexin-mediated cell-to-cell communication in diabetic nephropathy may represent an early sign of disease progression, but our understanding of the process remains severely limited. This review focuses on recent evidence demonstrating that glucose-evoked changes in connexin-mediated cell communication and associated purinergic signalling may contribute to the pathogenesis of kidney disease in diabetes, highlighting the tantalising potential of targeting these proteins as a novel therapeutic intervention.
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Affiliation(s)
- Gareth W Price
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Joe A Potter
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Bethany M Williams
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Chelsy L Cliff
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Paul E Squires
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Claire E Hills
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
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Calligari P, Torsello M, Bortoli M, Orian L, Polimeno A. Modelling of Ca2+-promoted structural effects in wild type and post-translationally modified Connexin26. MOLECULAR SIMULATION 2019. [DOI: 10.1080/08927022.2019.1690653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Paolo Calligari
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova, Italy
| | - Mauro Torsello
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova, Italy
| | - Marco Bortoli
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova, Italy
| | - Laura Orian
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova, Italy
| | - Antonino Polimeno
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova, Italy
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27
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Courson JA, Smith I, Do T, Landry PT, Hargrave A, Behzad AR, Hanlon SD, Rumbaut RE, Smith CW, Burns AR. Serial block-face scanning electron microscopy reveals neuronal-epithelial cell fusion in the mouse cornea. PLoS One 2019; 14:e0224434. [PMID: 31721785 PMCID: PMC6853292 DOI: 10.1371/journal.pone.0224434] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/14/2019] [Indexed: 11/28/2022] Open
Abstract
The cornea is the most highly innervated tissue in the body. It is generally accepted that corneal stromal nerves penetrate the epithelial basal lamina giving rise to intra-epithelial nerves. During the course of a study wherein we imaged corneal nerves in mice, we observed a novel neuronal-epithelial cell interaction whereby nerves approaching the epithelium in the cornea fused with basal epithelial cells, such that their plasma membranes were continuous and the neuronal axoplasm freely abutted the epithelial cytoplasm. In this study we sought to determine the frequency, distribution, and morphological profile of neuronal-epithelial cell fusion events within the cornea. Serial electron microscopy images were obtained from the anterior stroma in the paralimbus and central cornea of 8–10 week old C57BL/6J mice. We found evidence of a novel alternative behavior involving a neuronal-epithelial interaction whereby 42.8% of central corneal nerve bundles approaching the epithelium contain axons that fuse with basal epithelial cells. The average surface-to-volume ratio of a penetrating nerve was 3.32, while the average fusing nerve was smaller at 1.39 (p ≤ 0.0001). Despite this, both neuronal-epithelial cell interactions involve similarly sized discontinuities in the basal lamina. In order to verify the plasma membrane continuity between fused neurons and epithelial cells we used the lipophilic membrane tracer DiI. The majority of corneal nerves were labeled with DiI after application to the trigeminal ganglion and, consistent with our ultrastructural observations, fusion sites recognized as DiI-labeled basal epithelial cells were located at points of stromal nerve termination. These studies provide evidence that neuronal-epithelial cell fusion is a cell-cell interaction that occurs primarily in the central cornea, and fusing nerve bundles are morphologically distinct from penetrating nerve bundles. This is, to our knowledge, the first description of neuronal-epithelial cell fusion in the literature adding a new level of complexity to the current understanding of corneal innervation.
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Affiliation(s)
- Justin A. Courson
- University of Houston, College of Optometry, Houston, TX, United States of America
- * E-mail:
| | - Ian Smith
- University of Houston, College of Optometry, Houston, TX, United States of America
| | - Thao Do
- University of Houston, College of Optometry, Houston, TX, United States of America
| | - Paul T. Landry
- University of Houston, College of Optometry, Houston, TX, United States of America
| | - Aubrey Hargrave
- University of Houston, College of Optometry, Houston, TX, United States of America
| | - Ali R. Behzad
- King Abdullah University of Science and Technology (KAUST), Core Labs, Thuwal, Saudi Arabia
| | - Sam D. Hanlon
- University of Houston, College of Optometry, Houston, TX, United States of America
| | - Rolando E. Rumbaut
- Baylor College of Medicine, Children’s Nutrition Center, Houston, TX, United States of America
- Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, United States of America
| | - C. Wayne Smith
- Baylor College of Medicine, Children’s Nutrition Center, Houston, TX, United States of America
| | - Alan R. Burns
- University of Houston, College of Optometry, Houston, TX, United States of America
- Baylor College of Medicine, Children’s Nutrition Center, Houston, TX, United States of America
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The Effects of Calcium on Lipid-Protein Interactions and Ion Flux in the Cx26 Connexon Embedded into a POPC Bilayer. J Membr Biol 2019; 252:451-464. [PMID: 31440780 DOI: 10.1007/s00232-019-00088-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/07/2019] [Indexed: 01/07/2023]
Abstract
Gap junctions provide a communication pathway between adjacent cells. They are formed by paired connexons that reside in the plasma membrane of their respective cell and their activity can be modulated by the bilayer composition. In this work, we study the dynamic behavior of a Cx26 connexon embedded in a POPC lipid bilayer, studying: the membrane protein interactions and the ion flux though the connexon pore. We analyzed extensive atomistic molecular dynamics simulations for different conditions, with and without calcium ions. We found that lipid-protein interactions were mainly mediated by hydrogen bonds. Specific amino acids were identified forming hydrogen bonds with the POPC lipids (ARG98, ARG127, ARG165, ARG216, LYS22, LYS221, LYS223, LYS224, SER19, SER131, SER162, SER219, SER222, THR18 and TYR97, TYR155, TYR212, and TYR217). In the presence of calcium ions, we found subtle differences on the HB lifetimes. Finally, these MD simulations are able to identify and explain differential chlorine flux through the pore depending on the presence or absence of the calcium ions and its distribution within the pore.
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Gap Junction Intercellular Communication in the Carcinogenesis Hallmarks: Is This a Phenomenon or Epiphenomenon? Cells 2019; 8:cells8080896. [PMID: 31416286 PMCID: PMC6721698 DOI: 10.3390/cells8080896] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/03/2019] [Accepted: 08/12/2019] [Indexed: 12/24/2022] Open
Abstract
If occupational tumors are excluded, cancer causes are largely unknown. Therefore, it appeared useful to work out a theory explaining the complexity of this disease. More than fifty years ago the first demonstration that cells communicate with each other by exchanging ions or small molecules through the participation of connexins (Cxs) forming Gap Junctions (GJs) occurred. Then the involvement of GJ Intercellular Communication (GJIC) in numerous physiological cellular functions, especially in proliferation control, was proven and accounts for the growing attention elicited in the field of carcinogenesis. The aim of the present paper is to verify and discuss the role of Cxs, GJs, and GJIC in cancer hallmarks, pointing on the different involved mechanisms in the context of the multi-step theory of carcinogenesis. Functional GJIC acts both as a tumor suppressor and as a tumor enhancer in the metastatic stage. On the contrary, lost or non-functional GJs allow the uncontrolled proliferation of stem/progenitor initiated cells. Thus, GJIC plays a key role in many biological phenomena or epiphenomena related to cancer. Depending on this complexity, GJIC can be considered a tumor suppressor in controlling cell proliferation or a cancer ally, with possible preventive or therapeutic implications in both cases.
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30
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Yang L, Dong C, Tian L, Ji X, Yang L, Li L. Gadolinium Chloride Restores the Function of the Gap Junctional Intercellular Communication between Hepatocytes in a Liver Injury. Int J Mol Sci 2019; 20:E3748. [PMID: 31370360 PMCID: PMC6695937 DOI: 10.3390/ijms20153748] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/24/2019] [Accepted: 07/30/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Gadolinium chloride (GdCl3) has been reported to attenuate liver injury caused by a variety of toxicants. Gap junctional intercellular communication (GJIC) is thought to be essential in controlling liver homeostasis and pathology. Here we evaluate the effects of GdCl3 on functional GJIC and connexin expression in mouse models and primary hepatocytes. METHODS Mice were administered GdCl3 intraperitoneally the day before a carbon tetrachloride (CCl4) injection or bile duct ligation (BDL) operation. Primary hepatocytes were treated with CCl4 or lipopolysaccharides (LPS), with or without GdCl3. A scrape loading/dye transfer assay was performed to assess the GJIC function. The expression of connexins was examined by real-time reverse transcription polymerase chain reaction (RT-PCR), western blot and immunofluorescent staining. RESULTS CCl4 treatment or the BDL operation led to the dysfunction of GJIC and a down-regulation of Cx32 and Cx26 in injured liver. GdCl3 administration restored GJIC function between hepatocytes by facilitating the transfer of fluorescent dye from one cell into adjacent cells via GJIC, and markedly prevented the decrease of Cx32 and Cx26 in injured liver. In primary hepatocytes, CCl4 or LPS treatment induced an obvious decline of Cx32 and Cx26, whereas GdCl3 pretreatment prevented the down-regulation of connexins. In vivo GdCl3 protected hepatocytes and attenuated the liver inflammation and fibrosis in liver injury mouse models. CONCLUSION GdCl3 administration protects functional GJIC between hepatocytes, and prevents the decrease of connexin proteins at mRNA and protein levels during liver injury, leading to the alleviation of chronic liver injury.
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Affiliation(s)
- Le Yang
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China
| | - Chengbin Dong
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China
| | - Lei Tian
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China
| | - Xiaofang Ji
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China
| | - Lin Yang
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China
| | - Liying Li
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China.
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31
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Kolosov D, O'Donnell MJ. Helicokinin alters ion transport in the secondary cell-containing region of the Malpighian tubule of the larval cabbage looper Trichoplusia ni. Gen Comp Endocrinol 2019; 278:12-24. [PMID: 30012538 DOI: 10.1016/j.ygcen.2018.07.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/26/2018] [Accepted: 07/13/2018] [Indexed: 12/31/2022]
Abstract
Excretion in insects is accomplished by the combined actions of the Malpighian tubules (MTs) and hindgut, which together form the functional kidney. MTs of many insect groups consist of principal cells (PC) and secondary cells (SC). In most insect groups SCs are reported to secrete ions from haemolymph into the tubule lumen. Paradoxically, SCs in the MTs of the lepidopteran cabbage looper T. ni are used to reabsorb Na+ and K+ back into haemolymph. The current study was designed to investigate the effects and mode of action of the lepidopteran kinin, Helicokinin (HK), on ion transport in the SC-containing region of MT of T. ni. We identified a HK receptor (HK-R) homologue in T. ni and detected its expression in the SC-containing region of the MTs. The mRNA abundance of hk-r altered in response to changes in dietary K+ and Na+ content. HK-R immunolocalized to both PCs and SCs. Ramsay assays of preparations of the isolated distal ileac plexus (DIP) indicated that [HK] = 10-8 M: (i) decreased fluid secretion rate in unstimulated and serotonin-stimulated preparations, and (ii) increased [Na+]/[K+] ratio in the secreted fluid. Scanning ion-selective electrode technique measurements revealed that HK reduced: (i) K+ secretion by the PCs, and (ii) Na+ reabsorption by the SCs in intact tubules. In vitro incubation of the DIP with HK resulted in reduced mRNA abundance of hk-r as well as Na+/K+-ATPase subunit α (NKAα), Na+/K+/Cl- co-transporter (nkcc), Na+/H+ exchangers (nhe) 7 and 8, and aquaporin (aqp) 1. Taken together, results of the current study suggest that HK is capable of altering fluid secretion rate and [Na+]/[K+] ratio of the fluid, and that HK targets both PCs and SCs in the DIP of T. ni.
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Affiliation(s)
- Dennis Kolosov
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, ON L8S 4K1, Canada.
| | - Michael J O'Donnell
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, ON L8S 4K1, Canada
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Haustrate A, Hantute-Ghesquier A, Prevarskaya N, Lehen'kyi V. Monoclonal Antibodies Targeting Ion Channels and Their Therapeutic Potential. Front Pharmacol 2019; 10:606. [PMID: 31231216 PMCID: PMC6561378 DOI: 10.3389/fphar.2019.00606] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 05/14/2019] [Indexed: 12/27/2022] Open
Abstract
Monoclonal antibodies (mAbs) represent a rapidly growing pharmaceutical class of protein drugs that becomes an important part of the precision therapy. mAbs are characterized by their high specificity and affinity for the target antigen, which is mostly present on the cell surface. Ion channels are a large family of transmembrane proteins that control ion transport across the cell membrane. They are involved in almost all biological processes in both health and disease and are widely considered as prospective targets. However, no antibody-based drug targeting ion channel has been developed so far that has progressed to clinical use. Thus, we provide a comprehensive review of the elaborated mAbs against ion channels, describe their mechanisms of action, and discuss their therapeutic potential.
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Affiliation(s)
- Aurélien Haustrate
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France
| | - Aline Hantute-Ghesquier
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France
| | - Natalia Prevarskaya
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France
| | - V'yacheslav Lehen'kyi
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France.,FONDATION ARC, Villejuif, France
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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Huang BR, Tsai CH, Chen CC, Way TD, Kao JY, Liu YS, Lin HY, Lai SW, Lu DY. Curcumin Promotes Connexin 43 Degradation and Temozolomide-Induced Apoptosis in Glioblastoma Cells. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2019; 47:657-674. [PMID: 30974966 DOI: 10.1142/s0192415x19500344] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glioblastoma (GBM) is the most commonly occurring tumor in the cerebral hemispheres. Currently, temozolomide (TMZ), an alkylating agent that induces DNA strand breaks, is considered the frontline chemotherapeutic agent for GBM. Despite its frontline status, GBM patients commonly exhibit resistance to TMZ treatment. We have recently established and characterized TMZ-resistant human glioma cells. The aim of this study is to investigate whether curcumin modulates cell apoptosis through the alternation of the connexin 43 (Cx43) protein level in TMZ-resistant GBM. Overexpression of Cx43, but not ATP-binding cassette transporters (ABC transporters), was observed (approximately 2.2-fold) in TMZ-resistant GBM cells compared to the Cx43 levels in parental GBM cells. Furthermore, at a concentration of 10 μ M, curcumin significantly reduced Cx43 protein expression by about 40%. In addition, curcumin did not affect the expression of other connexins like Cx26 or epithelial-to-mesenchymal transition (EMT) proteins such as β -catenin or α E-catenin. Curcumin treatment led to an increase in TMZ-induced cell apoptosis from 4% to 8%. Importantly, it did not affect the mRNA expression level of Cx43. Concomitant treatment with the translation inhibitor cycloheximide (CHX) exerted additional effects on Cx43 degradation. Treatment with the autophagy inhibitor 3-MA (methyladenine) did not affect the curcumin-induced Cx43 degradation. Interestingly, treatment with the proteasome inhibitor MG132 (carbobenzoxy-Leu-Leu-leucinal) significantly negated the curcumin-induced Cx43 degradation, which suggests that curcumin-induced Cx43 degradation occurs through the ubiquitin-proteasome pathway.
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Affiliation(s)
- Bor-Ren Huang
- * Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,¶ Department of Neurosurgery, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan.,∥ School of Medicine, Tzu Chi University, Taichung, Taiwan
| | - Chon-Haw Tsai
- ** Department of Neurology, China Medical University Hospital, Taichung, Taiwan
| | - Chun-Chuan Chen
- †† Institute of Biochemistry, College of Life Science, National Chung Hsing University, Taichung, Taiwan
| | - Tzong-Der Way
- † Department of Biological Science and Technology, College of Life Sciences, China Medical University, Taichung, Taiwan
| | - Jung-Yie Kao
- †† Institute of Biochemistry, College of Life Science, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Shu Liu
- ‡ Department of Pharmacology, School of Medicine, China Medical University, Taichung, Taiwan
| | - Hsiao-Yun Lin
- ‡ Department of Pharmacology, School of Medicine, China Medical University, Taichung, Taiwan
| | - Sheng-Wei Lai
- § Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan
| | - Dah-Yuu Lu
- ‡ Department of Pharmacology, School of Medicine, China Medical University, Taichung, Taiwan.,‡‡ Department of Photonics and Communication Engineering, Asia University, Taichung, Taiwan
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Potential of cryo-EM for high-resolution structural analysis of gap junction channels. Curr Opin Struct Biol 2019; 54:78-85. [PMID: 30797124 DOI: 10.1016/j.sbi.2019.01.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/03/2018] [Accepted: 01/09/2019] [Indexed: 11/20/2022]
Abstract
Gap junction family proteins form conduits connecting the cytoplasm of adjacent cells, thereby enabling electrical and chemical coupling to maintain physiological homeostasis. Gap junction proteins comprise two gene families, connexins in chordates and innexins in pre-chordates. Their channel structures have been analyzed by electron or X-ray crystallography, but only a few atomic structures have been reported. Recent advances in single-particle cryo-electron microscopy (cryo-EM) will help to elucidate these structures further. Here the structural biology of gap junction channels utilizing crystallography and single-particle cryo-EM is overviewed to shed light on the functional mechanisms of cell-cell communication that are essential for multicellular organisms.
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36
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Kern DM, Oh S, Hite RK, Brohawn SG. Cryo-EM structures of the DCPIB-inhibited volume-regulated anion channel LRRC8A in lipid nanodiscs. eLife 2019; 8:42636. [PMID: 30775971 PMCID: PMC6395065 DOI: 10.7554/elife.42636] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 02/14/2019] [Indexed: 11/13/2022] Open
Abstract
Hypoosmotic conditions activate volume-regulated anion channels in vertebrate cells. These channels are formed by leucine-rich repeat-containing protein 8 (LRRC8) family members and contain LRRC8A in homo- or hetero-hexameric assemblies. Here, we present single-particle cryo-electron microscopy structures of Mus musculus LRRC8A in complex with the inhibitor DCPIB reconstituted in lipid nanodiscs. DCPIB plugs the channel like a cork in a bottle - binding in the extracellular selectivity filter and sterically occluding ion conduction. Constricted and expanded structures reveal coupled dilation of cytoplasmic LRRs and the channel pore, suggesting a mechanism for channel gating by internal stimuli. Conformational and symmetry differences between LRRC8A structures determined in detergent micelles and lipid bilayers related to reorganization of intersubunit lipid binding sites demonstrate a critical role for the membrane in determining channel structure. These results provide insight into LRRC8 gating and inhibition and the role of lipids in the structure of an ionic-strength sensing ion channel.
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Affiliation(s)
- David M Kern
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
| | - SeCheol Oh
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Stephen G Brohawn
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
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The Functional Implications of Endothelial Gap Junctions and Cellular Mechanics in Vascular Angiogenesis. Cancers (Basel) 2019; 11:cancers11020237. [PMID: 30781714 PMCID: PMC6406946 DOI: 10.3390/cancers11020237] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 02/08/2019] [Accepted: 02/13/2019] [Indexed: 12/27/2022] Open
Abstract
Angiogenesis—the sprouting and growth of new blood vessels from the existing vasculature—is an important contributor to tumor development, since it facilitates the supply of oxygen and nutrients to cancer cells. Endothelial cells are critically affected during the angiogenic process as their proliferation, motility, and morphology are modulated by pro-angiogenic and environmental factors associated with tumor tissues and cancer cells. Recent in vivo and in vitro studies have revealed that the gap junctions of endothelial cells also participate in the promotion of angiogenesis. Pro-angiogenic factors modulate gap junction function and connexin expression in endothelial cells, whereas endothelial connexins are involved in angiogenic tube formation and in the cell migration of endothelial cells. Several mechanisms, including gap junction function-dependent or -independent pathways, have been proposed. In particular, connexins might have the potential to regulate cell mechanics such as cell morphology, cell migration, and cellular stiffness that are dynamically changed during the angiogenic processes. Here, we review the implication for endothelial gap junctions and cellular mechanics in vascular angiogenesis.
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Li WC, Gao H, Gao J, Wang ZJ. Antiarrhythmic effect of sevoflurane as an additive to HTK solution on reperfusion arrhythmias induced by hypothermia and ischaemia is associated with the phosphorylation of connexin 43 at serine 368. BMC Anesthesiol 2019; 19:5. [PMID: 30621602 PMCID: PMC6325883 DOI: 10.1186/s12871-018-0656-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/29/2018] [Indexed: 12/22/2022] Open
Abstract
Background Reperfusion ventricular arrhythmia (RA) associated with hypothermic ischaemic storage is increasingly recognized as a substantial contributor to adverse consequences after heart transplantation. Ischemia- or hypothermia-induced gap junction (GJ) remodelling is closely linked to RA. Reducing GJ remodelling contributes to RA attenuation and is important in heart transplantation. However, sevoflurane has an antiarrhythmic effect associated with the connexin 43 (Cx43) protein that has not yet been fully established. Methods Hearts were divided into two groups according to a random number table: all hearts were arrested by an infusion of histidine-tryptophan-ketoglutarate (HTK) solution (4 °C) followed by (1) storage in HTK solution (4 °C) alone for 6 h (n = 8, Control group) or (2) storage in HTK solution supplemented with sevoflurane (2.5%) (4 °C) for 6 h (n = 8, Sevo-HTK group). First, the total Cx43 level and the phosphorylation of Cx43 at Ser368 (Cx43-pS368) were assessed by Western blotting, and the distribution of Cx43 was assessed by immunohistochemistry. Second, programmed electrical stimulation (PES) and monophasic action potential (MAP) recording were used to analyse the MAP duration (MAPD), conduction velocity (CV) and transmural repolarization dispersion (TDR). In addition, haematoxylin and eosin (HE) and terminal deoxynucleotidyl transferase-dUTP nick end labelling (TUNEL) staining were individually used to investigate the degree of myocardial pathological damage and cell apoptosis. Finally, bipolar electrograms were used to record the graft re-beating time and monitor RA during reperfusion for 15 to 30 min. Results Sevo-HTK solution relatively increased the total Cx43 (P < 0.01) and Cx43-pS368 (P < 0.01) levels and prevented Cx43 redistribution (P < 0.05) and CV slowing (P < 0.001) but did not change TDR (P > 0.05). Additionally, the Cx43-pS368/total Cx43 ratio (P>0.05) was similar in the two groups. However, with Sevo-HTK solution, the graft re-beating times were shortened, myocardial pathological damage was ameliorated, and the number of apoptotic cells was markedly decreased. Conclusion The reduction in hypothermia and ischaemia-induced reperfusion arrhythmias by the addition of sevoflurane to HTK solution may be related to the phosphorylation of Cx43 at serine 368.
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Affiliation(s)
- Wei Chao Li
- Department of Anesthesiology, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, China
| | - Hong Gao
- Department of Anesthesiology, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, China.
| | - Ju Gao
- Department of Anaesthesiology, North Jiangsu People's Hospital, Yangzhou University, Yangzhou, China
| | - Zi Jun Wang
- Department of Anesthesiology, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, China
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Pogoda K, Kameritsch P, Mannell H, Pohl U. Connexins in the control of vasomotor function. Acta Physiol (Oxf) 2019; 225:e13108. [PMID: 29858558 DOI: 10.1111/apha.13108] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 12/13/2022]
Abstract
Vascular endothelial cells, as well as smooth muscle cells, show heterogeneity with regard to their receptor expression and reactivity. For the vascular wall to act as a functional unit, the various cells' responses require integration. Such an integration is not only required for a homogeneous response of the vascular wall, but also for the vasomotor behaviour of consecutive segments of the microvascular arteriolar tree. As flow resistances of individual sections are connected in series, sections require synchronization and coordination to allow effective changes of conductivity and blood flow. A prerequisite for the local coordination of individual vascular cells and different sections of an arteriolar tree is intercellular communication. Connexins are involved in a dual manner in this coordination. (i) By forming gap junctions between cells, they allow an intercellular exchange of signalling molecules and electrical currents. In particular, the spread of electrical currents allows for coordination of cell responses over longer distances. (ii) Connexins are able to interact with other proteins to form signalling complexes. In this way, they can modulate and integrate individual cells' responses also in a channel-independent manner. This review outlines mechanisms allowing the vascular connexins to exert their coordinating function and to regulate the vasomotor reactions of blood vessels both locally, and in vascular networks. Wherever possible, we focus on the vasomotor behaviour of small vessels and arterioles which are the main vessels determining vascular resistance, blood pressure and local blood flow.
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Affiliation(s)
- K. Pogoda
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - P. Kameritsch
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - H. Mannell
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
| | - U. Pohl
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich Germany
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40
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Albano JMR, Mussini N, Toriano R, Facelli JC, Ferraro MB, Pickholz M. Calcium interactions with Cx26 hemmichannel: Spatial association between MD simulations biding sites and variant pathogenicity. Comput Biol Chem 2018; 77:331-342. [PMID: 30466042 DOI: 10.1016/j.compbiolchem.2018.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/08/2018] [Accepted: 11/08/2018] [Indexed: 01/23/2023]
Abstract
Connexinophaties are a collective of diseases related to connexin channels and hemichannels. In particular many Cx26 alterations are strongly associated to human deafness. Calcium plays an important role on this structures regulation. Here, using calcium as a probe, extensive atomistic Molecular Dynamics simulations were performed on the Cx26 hemichannel embedded in a lipid bilayer. Exploring different initial conditions and calcium concentration, simulation reached ∼4 μs. Several analysis were carried out in order to reveal the calcium distribution and localization, such as electron density profiles, density maps and distance time evolution, which is directly associated to the interaction energy. Specific amino acid interactions with calcium and their stability were capture within this context. Few of these sites such as, GLU42, GLU47, GLY45 and ASP50, were already suggested in the literature. Besides, we identified novel calcium biding sites: ASP2, ASP117, ASP159, GLU114, GLU119, GLU120 and VAL226. To the best of our knowledge, this is the first time that these sites are reported within this context. Furthermore, since various pathologies involving the Cx26 hemichannel are associated with pathogenic variants in the corresponding CJB2 gene, using ClinVar, we were able to spatially associate the 3D positions of the identified calcium binding sites within the framework of this work with reported pathogenic variants in the CJB2 gene. This study presents a first step on finding associations between molecular features and pathological variants of the Cx26 hemichannel.
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Affiliation(s)
- Juan M R Albano
- Facultad de Ciencias Exactas y Naturales, Departamento de Física, Universidad de Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, IFIBA, Buenos Aires, Argentina
| | - Nahuel Mussini
- Facultad de Ciencias Exactas y Naturales, Departamento de Física, Universidad de Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, IFIBA, Buenos Aires, Argentina
| | - Roxana Toriano
- Facultad de Medicina, Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Buenos Aires, Argentina; CONICET - Universidad de Buenos Aires, IFIBIO Houssay, Buenos Aires, Argentina
| | - Julio C Facelli
- Department of Biomedical Informatics, The University of Utah, 421 Wakara Way, Suite 140, Salt Lake City, UT 84108, USA.
| | - Marta B Ferraro
- Facultad de Ciencias Exactas y Naturales, Departamento de Física, Universidad de Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, IFIBA, Buenos Aires, Argentina
| | - Mónica Pickholz
- Facultad de Ciencias Exactas y Naturales, Departamento de Física, Universidad de Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, IFIBA, Buenos Aires, Argentina
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Oshima A. Structure of an innexin gap junction channel and cryo-EM sample preparation. Microscopy (Oxf) 2018; 66:371-379. [PMID: 29036409 PMCID: PMC6084585 DOI: 10.1093/jmicro/dfx035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/31/2017] [Indexed: 01/05/2023] Open
Abstract
Gap junction channels are essential for mediating intercellular communication in most multicellular organisms. Two gene families encode gap junction channels, innexin and connexin. Although the sequence similarity between these two families based on bioinformatics is not conclusively determined, the gap junction channels encoded by these two gene families are structurally and functionally analogous. We recently reported an atomic structure of an invertebrate innexin gap junction channel using single-particle cryo-electron microscopy. Our findings revealed that connexin and innexin families share several structural properties with regard to their monomeric and oligomeric structures, while simultaneously suggesting a diversity of gap junction channels in nature. This review summarizes cutting-edge progress toward determining an innexin gap junction channel structure, as well as essential tips for preparing cryo-electron microscopy samples for high-resolution structural analysis of an innexin gap junction channel.
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Affiliation(s)
- Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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42
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Kefauver JM, Saotome K, Dubin AE, Pallesen J, Cottrell CA, Cahalan SM, Qiu Z, Hong G, Crowley CS, Whitwam T, Lee WH, Ward AB, Patapoutian A. Structure of the human volume regulated anion channel. eLife 2018; 7:38461. [PMID: 30095067 PMCID: PMC6086657 DOI: 10.7554/elife.38461] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/16/2018] [Indexed: 01/03/2023] Open
Abstract
SWELL1 (LRRC8A) is the only essential subunit of the Volume Regulated Anion Channel (VRAC), which regulates cellular volume homeostasis and is activated by hypotonic solutions. SWELL1, together with four other LRRC8 family members, potentially forms a vastly heterogeneous cohort of VRAC channels with different properties; however, SWELL1 alone is also functional. Here, we report a high-resolution cryo-electron microscopy structure of full-length human homo-hexameric SWELL1. The structure reveals a trimer of dimers assembly with symmetry mismatch between the pore-forming domain and the cytosolic leucine-rich repeat (LRR) domains. Importantly, mutational analysis demonstrates that a charged residue at the narrowest constriction of the homomeric channel is an important pore determinant of heteromeric VRAC. Additionally, a mutation in the flexible N-terminal portion of SWELL1 affects pore properties, suggesting a putative link between intracellular structures and channel regulation. This structure provides a scaffold for further dissecting the heterogeneity and mechanism of activation of VRAC. Every cell needs to regulate its internal volume or it will burst. Most of a cell’s volume is a watery mixture of salts, proteins and other molecules. A cell can take in more water from its surroundings, diluting this mixture and causing the cell to expand. If a cell starts to take up too much water, it will open channel proteins in its outer membrane called volume regulated anion channels (or VRACs for short). An open VRAC allows negatively charged ions to leave the cell, and in the process causes water to leave the cell too. This relieves the pressure inside the cell, and the cell starts to shrink. The structure of a VRAC is thought to contain six subunits, and most include at least two different kinds of subunit. Some of the subunits must be a protein called SWELL1 (which is also known as LRRC8A). The other subunits can be any of four similar proteins from the same protein family. Since a VRAC can contain additional subunits drawing from this pool of five proteins, many structures are possible. But it remains unclear exactly how the structure of a VRAC allows it to sense and regulate the volume of a cell. This is partly because scientists do not have enough information about the architecture of this protein to understand how it might work. Using electron microscopes, Kefauver et al. have now captured detailed images of a VRAC composed entirely of human SWELL1 proteins. The overall structure of VRAC resembles a six-legged jellyfish, with a pore on the cell’s exterior passing through a constricted dome followed by three pairs of arms that extend into the cell’s interior. Given the observed structure, Kefauver et al. speculate that the arms of the SWELL1 proteins sense salt concentrations within the cell (to tell if its become diluted by an influx of water) and then interact with the rest of the channel. In response to these interactions, the domed part of the VRAC constricts or dilates to help regulate the cell’s volume. Molecular biologists can now use these structural details to further study the fundamentals behind how cells regulate their volume. This model will also improve scientific understanding of how diverse VRAC structures differ in their responses to changes in pressure within cells.
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Affiliation(s)
- Jennifer M Kefauver
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States.,Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Kei Saotome
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States.,Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Adrienne E Dubin
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Jesper Pallesen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Christopher A Cottrell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Stuart M Cahalan
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Zhaozhu Qiu
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Gunhee Hong
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Christopher S Crowley
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States.,Department of Dermatology, University of California, San Diego, San Diego, United States
| | - Tess Whitwam
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Wen-Hsin Lee
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Ardem Patapoutian
- Department of Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
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Ge Z, Diao H, Ji X, Liu Q, Zhang X, Wu Q. Gap junctional intercellular communication and endoplasmic reticulum stress regulate chronic cadmium exposure induced apoptosis in HK-2 cells. Toxicol Lett 2018; 288:35-43. [DOI: 10.1016/j.toxlet.2018.02.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 01/23/2018] [Accepted: 02/08/2018] [Indexed: 12/23/2022]
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44
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Raškevičius V, Jotautis V, Rimkutė L, Marandykina A, Kazokaitė M, Kairys V, Skeberdis VA. Molecular basis for potentiation of Cx36 gap junction channel conductance by n-alcohols and general anesthetics. Biosci Rep 2018; 38:BSR20171323. [PMID: 29298877 PMCID: PMC5803492 DOI: 10.1042/bsr20171323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/22/2017] [Accepted: 01/01/2018] [Indexed: 01/01/2023] Open
Abstract
In our recent study, we have demonstrated that short carbon chain n-alcohols (up to octanol) stimulated while long carbon chain n-alcohols inhibited the conductance of connexin (Cx) 36 (Cx36) gap junction (GJ) channels. In contrast, GJ channels composed of other types of Cxs all were inhibited by n-alcohols independent of their carbon chain length. To identify the putative structural domains of Cx36, responsible for the dual effect of n-alcohols, we performed structural modeling of Cx36 protein docking with hexanol and isoflurane that stimulated as well as nonanol and carbenoxolone that inhibited the conductance of Cx36 GJs and revealed their multiple common docking sites and a single pocket accessible only to hexanol and isoflurane. The pocket is located in the vicinity of three unique cysteine residues, namely C264 in the fourth, and C92 and C87 in the second transmembrane domain of the neighboring Cx36 subunits. To examine the hypothesis that disulphide bonding might be involved in the stimulatory effect of hexanol and isoflurane, we generated cysteine substitutions in Cx36 and demonstrated by a dual whole-cell patch-clamp technique that in HeLa (human cervix carcinoma cell line) and N2A (mouse neuroblastoma cell line) cells these mutations reversed the stimulatory effect of hexanol and isoflurane to inhibitory one, typical of other Cxs that lack respective cysteines and a specific docking pocket for these compounds. Our findings suggest that the stimulatory effect of hexanol and isoflurane on Cx36 GJ conductance could be achieved by re-shuffling of the inter-subunit disulphide bond between C264 and C92 to the intra-subunit one between C264 and C87.
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Affiliation(s)
- Vytautas Raškevičius
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Vaidas Jotautis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Lina Rimkutė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Alina Marandykina
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Mintautė Kazokaitė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Visvaldas Kairys
- Institute of Biotechnology, Vilnius University, Vilnius LT-10257, Lithuania
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Flores AF, Varela-Vazquez A, Mayan MD, Fonseca E. Expression of connexin 43 in the human hair follicle: emphasis on the connexin 43 protein levels in the bulge and through the keratinization process. J Cutan Pathol 2017; 45:8-15. [DOI: 10.1111/cup.13050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 09/13/2017] [Accepted: 09/21/2017] [Indexed: 12/22/2022]
Affiliation(s)
- Angel Fernandez Flores
- Department of Cellular Pathology; Hospital El Bierzo; Ponferrada Spain
- Department of Cellular Pathology; Hospital de la Reina; Ponferrada Spain
- CellCOM-SB Group, Institute for Biomedical Research of A Coruña (INIBIC); University of A Coruña (UDC); A Coruña Spain
| | - Adrian Varela-Vazquez
- CellCOM-SB Group, Institute for Biomedical Research of A Coruña (INIBIC); University of A Coruña (UDC); A Coruña Spain
| | - Maria D. Mayan
- CellCOM-SB Group, Institute for Biomedical Research of A Coruña (INIBIC); University of A Coruña (UDC); A Coruña Spain
| | - Eduardo Fonseca
- CellCOM-SB Group, Institute for Biomedical Research of A Coruña (INIBIC); University of A Coruña (UDC); A Coruña Spain
- Department of Dermatology; University Hospital of A Coruña; A Coruña Spain
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The Role of Gap Junction-Mediated Endothelial Cell-Cell Interaction in the Crosstalk between Inflammation and Blood Coagulation. Int J Mol Sci 2017; 18:ijms18112254. [PMID: 29077057 PMCID: PMC5713224 DOI: 10.3390/ijms18112254] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/21/2017] [Accepted: 10/24/2017] [Indexed: 12/29/2022] Open
Abstract
Endothelial cells (ECs) play a pivotal role in the crosstalk between blood coagulation and inflammation. Endothelial cellular dysfunction underlies the development of vascular inflammatory diseases. Recent studies have revealed that aberrant gap junctions (GJs) and connexin (Cx) hemichannels participate in the progression of cardiovascular diseases such as cardiac infarction, hypertension and atherosclerosis. ECs can communicate with adjacent ECs, vascular smooth muscle cells, leukocytes and platelets via GJs and Cx channels. ECs dynamically regulate the expression of numerous Cxs, as well as GJ functionality, in the context of inflammation. Alterations to either result in various side effects across a wide range of vascular functions. Here, we review the roles of endothelial GJs and Cx channels in vascular inflammation, blood coagulation and leukocyte adhesion. In addition, we discuss the relevant molecular mechanisms that endothelial GJs and Cx channels regulate, both the endothelial functions and mechanical properties of ECs. A better understanding of these processes promises the possibility of pharmacological treatments for vascular pathogenesis.
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Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
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48
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Maes M, Crespo Yanguas S, Willebrords J, Weemhoff JL, da Silva TC, Decrock E, Lebofsky M, Pereira IVA, Leybaert L, Farhood A, Jaeschke H, Cogliati B, Vinken M. Connexin hemichannel inhibition reduces acetaminophen-induced liver injury in mice. Toxicol Lett 2017; 278:30-37. [PMID: 28687253 PMCID: PMC5800489 DOI: 10.1016/j.toxlet.2017.07.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/27/2017] [Accepted: 07/01/2017] [Indexed: 02/07/2023]
Abstract
Historically, connexin hemichannels have been considered as structural precursors of gap junctions. However, accumulating evidence points to independent roles for connexin hemichannels in cellular signaling by connecting the intracellular compartment with the extracellular environment. Unlike gap junctions, connexin hemichannels seem to be mainly activated in pathological processes. The present study was set up to test the potential involvement of hemichannels composed of connexin32 and connexin43 in acute hepatotoxicity induced by acetaminophen. Prior to this, in vitro testing was performed to confirm the specificity and efficacy of TAT-Gap24 and TAT-Gap19 in blocking connexin32 and connexin43 hemichannels, respectively. Subsequently, mice were overdosed with acetaminophen followed by treatment with TAT-Gap24 or TAT-Gap19 or a combination of both after 1.5h. Sampling was performed 3, 6, 24 and 48h following acetaminophen administration. Evaluation of the effects of connexin hemichannel inhibition was based on a series of clinically relevant read-outs, measurement of inflammatory cytokines and oxidative stress. Subsequent treatment of acetaminophen-overdosed mice with TAT-Gap19 only marginally affected liver injury. In contrast, a significant reduction in serum alanine aminotransferase activity was found upon administration of TAT-Gap24 to intoxicated animals. Furthermore, co-treatment of acetaminophen-overdosed mice with both peptides revealed an additive effect as even lower serum alanine aminotransferase activity was observed. Blocking of connexin32 or connexin43 hemichannels individually was found to decrease serum quantities of pro-inflammatory cytokines, while no effects were observed on the occurrence of hepatic oxidative stress. This study shows for the first time a role for connexin hemichannels in acetaminophen-induced acute liver failure.
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Affiliation(s)
- Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium.
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium.
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium.
| | - James L Weemhoff
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, United States.
| | - Tereza Cristina da Silva
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium.
| | - Margitta Lebofsky
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, United States.
| | - Isabel Veloso Alves Pereira
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium.
| | - Anwar Farhood
- Department of Pathology, St. David's North Austin Medical Center, Austin, United States.
| | - Hartmut Jaeschke
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, United States.
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium.
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49
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Bai D, Yue B, Aoyama H. Crucial motifs and residues in the extracellular loops influence the formation and specificity of connexin docking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:9-21. [PMID: 28693896 DOI: 10.1016/j.bbamem.2017.07.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/25/2017] [Accepted: 07/03/2017] [Indexed: 12/19/2022]
Abstract
Most of the early studies on gap junction (GJ) channel function and docking compatibility were on rodent connexins, while recent research on GJ channels gradually shifted from rodent to human connexins largely due to the fact that mutations in many human connexin genes are found to associate with inherited human diseases. The studies on human connexins have revealed some key differences from those found in rodents, calling for a comprehensive characterization of human GJ channels. Functional studies revealed that docking and formation of functional GJ channels between two hemichannels are possible only between docking-compatible connexins. Two groups of docking-compatible rodent connexins have been identified. Compatibility is believed to be due to their amino acid residue differences at the extracellular loop domains (E1 and E2). Sequence alignment of the E1 and E2 domains of all connexins known to make GJs revealed that they are highly conserved and show high sequence identity with human Cx26, which is the only connexin with near atomic resolution GJ structure. We hypothesize that different connexins have a similar structure as that of Cx26 at the E1 and E2 domains and use the corresponding residues in their E1 and E2 domains for docking. Based on the Cx26 GJ structure and sequence analysis of well-studied connexins, we propose that the E1-E1 docking interactions are staggered with each E1 interacting with two E1s on the docked connexon. The putative E1 docking residues are conserved in both docking-compatible and -incompatible connexins, indicating that E1 does not likely serve a role in docking compatibility. However, in the case of E2-E2 docking interactions, the putative docking residues are only conserved within the docking-compatible connexins, suggesting the E2 is likely to serve the function of docking compatibility. Docking compatibility studies on human connexins have attracted a lot of attention due to the fact that putative docking residues are mutational hotspots for several connexin-linked human diseases. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
| | - Benny Yue
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Hiroshi Aoyama
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
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50
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Roy S, Jiang JX, Li AF, Kim D. Connexin channel and its role in diabetic retinopathy. Prog Retin Eye Res 2017; 61:35-59. [PMID: 28602949 DOI: 10.1016/j.preteyeres.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/30/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.
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Affiliation(s)
- Sayon Roy
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - An-Fei Li
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan
| | - Dongjoon Kim
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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