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Lukowicz-Bedford RM, Eisen JS, Miller AC. Gap-junction-mediated bioelectric signaling required for slow muscle development and function in zebrafish. Curr Biol 2024; 34:3116-3132.e5. [PMID: 38936363 PMCID: PMC11265983 DOI: 10.1016/j.cub.2024.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/11/2024] [Accepted: 06/04/2024] [Indexed: 06/29/2024]
Abstract
Bioelectric signaling, intercellular communication facilitated by membrane potential and electrochemical coupling, is emerging as a key regulator of animal development. Gap junction (GJ) channels can mediate bioelectric signaling by creating a fast, direct pathway between cells for the movement of ions and other small molecules. In vertebrates, GJ channels are formed by a highly conserved transmembrane protein family called the connexins. The connexin gene family is large and complex, creating challenges in identifying specific connexins that create channels within developing and mature tissues. Using the embryonic zebrafish neuromuscular system as a model, we identify a connexin conserved across vertebrate lineages, gjd4, which encodes the Cx46.8 protein, that mediates bioelectric signaling required for slow muscle development and function. Through mutant analysis and in vivo imaging, we show that gjd4/Cx46.8 creates GJ channels specifically in developing slow muscle cells. Using genetics, pharmacology, and calcium imaging, we find that spinal-cord-generated neural activity is transmitted to developing slow muscle cells, and synchronized activity spreads via gjd4/Cx46.8 GJ channels. Finally, we show that bioelectrical signal propagation within the developing neuromuscular system is required for appropriate myofiber organization and that disruption leads to defects in behavior. Our work reveals a molecular basis for GJ communication among developing muscle cells and reveals how perturbations to bioelectric signaling in the neuromuscular system may contribute to developmental myopathies. Moreover, this work underscores a critical motif of signal propagation between organ systems and highlights the pivotal role of GJ communication in coordinating bioelectric signaling during development.
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Affiliation(s)
| | - Judith S Eisen
- University of Oregon, Institute of Neuroscience, Eugene, OR 97405, USA
| | - Adam C Miller
- University of Oregon, Institute of Neuroscience, Eugene, OR 97405, USA.
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2
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Jagielnicki M, Kucharska I, Bennett BC, Harris AL, Yeager M. Connexin Gap Junction Channels and Hemichannels: Insights from High-Resolution Structures. BIOLOGY 2024; 13:298. [PMID: 38785780 PMCID: PMC11117596 DOI: 10.3390/biology13050298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 03/29/2024] [Accepted: 04/08/2024] [Indexed: 05/25/2024]
Abstract
Connexins (Cxs) are a family of integral membrane proteins, which function as both hexameric hemichannels (HCs) and dodecameric gap junction channels (GJCs), behaving as conduits for the electrical and molecular communication between cells and between cells and the extracellular environment, respectively. Their proper functioning is crucial for many processes, including development, physiology, and response to disease and trauma. Abnormal GJC and HC communication can lead to numerous pathological states including inflammation, skin diseases, deafness, nervous system disorders, and cardiac arrhythmias. Over the last 15 years, high-resolution X-ray and electron cryomicroscopy (cryoEM) structures for seven Cx isoforms have revealed conservation in the four-helix transmembrane (TM) bundle of each subunit; an αβ fold in the disulfide-bonded extracellular loops and inter-subunit hydrogen bonding across the extracellular gap that mediates end-to-end docking to form a tight seal between hexamers in the GJC. Tissue injury is associated with cellular Ca2+ overload. Surprisingly, the binding of 12 Ca2+ ions in the Cx26 GJC results in a novel electrostatic gating mechanism that blocks cation permeation. In contrast, acidic pH during tissue injury elicits association of the N-terminal (NT) domains that sterically blocks the pore in a "ball-and-chain" fashion. The NT domains under physiologic conditions display multiple conformational states, stabilized by protein-protein and protein-lipid interactions, which may relate to gating mechanisms. The cryoEM maps also revealed putative lipid densities within the pore, intercalated among transmembrane α-helices and between protomers, the functions of which are unknown. For the future, time-resolved cryoEM of isolated Cx channels as well as cryotomography of GJCs and HCs in cells and tissues will yield a deeper insight into the mechanisms for channel regulation. The cytoplasmic loop (CL) and C-terminal (CT) domains are divergent in sequence and length, are likely involved in channel regulation, but are not visualized in the high-resolution X-ray and cryoEM maps presumably due to conformational flexibility. We expect that the integrated use of synergistic physicochemical, spectroscopic, biophysical, and computational methods will reveal conformational dynamics relevant to functional states. We anticipate that such a wealth of results under different pathologic conditions will accelerate drug discovery related to Cx channel modulation.
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Affiliation(s)
- Maciej Jagielnicki
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, Department of Chemistry, University of Miami, 1201 Memorial Drive, Miami, FL 33146, USA; (M.J.); (I.K.)
| | - Iga Kucharska
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, Department of Chemistry, University of Miami, 1201 Memorial Drive, Miami, FL 33146, USA; (M.J.); (I.K.)
| | - Brad C. Bennett
- Department of Biological and Environmental Sciences, Howard College of Arts and Sciences, Samford University, Birmingham, AL 35229, USA;
| | - Andrew L. Harris
- Rutgers New Jersey Medical School, Department of Pharmacology, Physiology and Neuroscience, Newark, NJ 07103, USA;
| | - Mark Yeager
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, Department of Chemistry, University of Miami, 1201 Memorial Drive, Miami, FL 33146, USA; (M.J.); (I.K.)
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL 33146, USA
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3
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Mao W, Chen S. Assembly mechanisms of the neuronal gap junction channel connexin 36 elucidated by Cryo-EM. Arch Biochem Biophys 2024; 754:109959. [PMID: 38490311 DOI: 10.1016/j.abb.2024.109959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/20/2024] [Accepted: 03/12/2024] [Indexed: 03/17/2024]
Abstract
Electrical synapses are essential components of neural circuits. Neuronal signal transduction across electrical synapses is primarily mediated by gap junction channels composed of Connexin36 (Cx36), the lack of which causes impaired electrical coupling between certain neurons including cortical interneurons and thalamic reticular nucleus (TRN) neurons. However, the structural basis underlying Cx36 function and assembly remains elusive. Recently, Lee et al. reported cryo-EM structures of Cx36, thus provided first insights of its gating mechanism. Here, we report a consistent cryo-EM structure of Cx36 determined in parallel, and describe unique interactions underpinning its assembly mechanism in complementary to the competing work. In particular, we found non-canonical electrostatic interactions between protomers from opposing hemichannels and a steric complementary site between adjacent protomers within a hemichannel, which together provide a structural explanation for the assembly specificity in homomeric and heteromeric gap junction channels.
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Affiliation(s)
- Wenxuan Mao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China; Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shanshuang Chen
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China; Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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4
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Leighton SE, Wong RS, Lucaciu SA, Hauser A, Johnston D, Stathopulos PB, Bai D, Penuela S, Laird DW. Cx31.1 can selectively intermix with co-expressed connexins to facilitate its assembly into gap junctions. J Cell Sci 2024; 137:jcs261631. [PMID: 38533727 PMCID: PMC11058089 DOI: 10.1242/jcs.261631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/05/2024] [Indexed: 03/28/2024] Open
Abstract
Connexins are channel-forming proteins that function to facilitate gap junctional intercellular communication. Here, we use dual cell voltage clamp and dye transfer studies to corroborate past findings showing that Cx31.1 (encoded by GJB5) is defective in gap junction channel formation, illustrating that Cx31.1 alone does not form functional gap junction channels in connexin-deficient mammalian cells. Rather Cx31.1 transiently localizes to the secretory pathway with a subpopulation reaching the cell surface, which is rarely seen in puncta reminiscent of gap junctions. Intracellular retained Cx31.1 was subject to degradation as Cx31.1 accumulated in the presence of proteasomal inhibition, had a faster turnover when Cx43 was present and ultimately reached lysosomes. Although intracellularly retained Cx31.1 was found to interact with Cx43, this interaction did not rescue its delivery to the cell surface. Conversely, the co-expression of Cx31 dramatically rescued the assembly of Cx31.1 into gap junctions where gap junction-mediated dye transfer was enhanced. Collectively, our results indicate that the localization and functional status of Cx31.1 is altered through selective interplay with co-expressed connexins, perhaps suggesting Cx31.1 is a key regulator of intercellular signaling in keratinocytes.
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Affiliation(s)
- Stephanie E. Leighton
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Robert S. Wong
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Sergiu A. Lucaciu
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Alexandra Hauser
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Danielle Johnston
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Western's Bone and Joint Institute, The Dr. Sandy Kirkley Centre for Musculoskeletal Research, University Hospital, London, ON N6A 5B9, Canada
- Division of Experimental Oncology, Department of Oncology, University of Western Ontario, London, ON N6A 5W9, Canada
| | - Dale W. Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
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5
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Lee HC, Oliveira NMM, Hastings C, Baillie-Benson P, Moverley AA, Lu HC, Zheng Y, Wilby EL, Weil TT, Page KM, Fu J, Moris N, Stern CD. Regulation of long-range BMP gradients and embryonic polarity by propagation of local calcium-firing activity. Nat Commun 2024; 15:1463. [PMID: 38368410 PMCID: PMC10874436 DOI: 10.1038/s41467-024-45772-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 02/02/2024] [Indexed: 02/19/2024] Open
Abstract
Many amniote vertebrate species including humans can form identical twins from a single embryo, but this only occurs rarely. It has been suggested that the primitive-streak-forming embryonic region emits signals that inhibit streak formation elsewhere but the signals involved, how they are transmitted and how they act has not been elucidated. Here we show that short tracks of calcium firing activity propagate through extraembryonic tissue via gap junctions and prevent ectopic primitive streak formation in chick embryos. Cross-regulation of calcium activity and an inhibitor of primitive streak formation (Bone Morphogenetic Protein, BMP) via NF-κB and NFAT establishes a long-range BMP gradient spanning the embryo. This mechanism explains how embryos of widely different sizes can maintain positional information that determines embryo polarity. We provide evidence for similar mechanisms in two different human embryo models and in Drosophila, suggesting an ancient evolutionary origin.
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Affiliation(s)
- Hyung Chul Lee
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
- School of Biological Sciences and Technology, College of Natural Sciences, Chonnam National University, 77 Yongbong-ro, Gwangju, 61186, Korea.
| | - Nidia M M Oliveira
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- College of Professional Services, Murdoch University, 90 South St, Murdoch, WA, 6150, Australia
| | - Cato Hastings
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | | | - Adam A Moverley
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hui-Chun Lu
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- Centre for Craniofacial & Regenerative Biology, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, Guy's Tower, London, SE1 9RT, UK
| | - Yi Zheng
- Departments of Mechanical Engineering, Biomedical Engineering, and Cell & Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, USA
- BioInspired Syracuse Institute for Materials and Living Systems, Syracuse University, Syracuse, NY, USA
| | - Elise L Wilby
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Timothy T Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Karen M Page
- Department of Mathematics, University College London, Gower Street, London, WC1E 6BT, UK
| | - Jianping Fu
- Departments of Mechanical Engineering, Biomedical Engineering, and Cell & Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Naomi Moris
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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6
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Lukowicz-Bedford RM, Eisen JS, Miller AC. Gap junction mediated bioelectric coordination is required for slow muscle development, organization, and function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572619. [PMID: 38187655 PMCID: PMC10769300 DOI: 10.1101/2023.12.20.572619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Bioelectrical signaling, intercellular communication facilitated by membrane potential and electrochemical coupling, is emerging as a key regulator of animal development. Gap junction (GJ) channels can mediate bioelectric signaling by creating a fast, direct pathway between cells for the movement of ions and other small molecules. In vertebrates, GJ channels are formed by a highly conserved transmembrane protein family called the Connexins. The connexin gene family is large and complex, presenting a challenge in identifying the specific Connexins that create channels within developing and mature tissues. Using the embryonic zebrafish neuromuscular system as a model, we identify a connexin conserved across vertebrate lineages, gjd4, which encodes the Cx46.8 protein, that mediates bioelectric signaling required for appropriate slow muscle development and function. Through a combination of mutant analysis and in vivo imaging we show that gjd4/Cx46.8 creates GJ channels specifically in developing slow muscle cells. Using genetics, pharmacology, and calcium imaging we find that spinal cord generated neural activity is transmitted to developing slow muscle cells and synchronized activity spreads via gjd4/Cx46.8 GJ channels. Finally, we show that bioelectrical signal propagation within the developing neuromuscular system is required for appropriate myofiber organization, and that disruption leads to defects in behavior. Our work reveals the molecular basis for GJ communication among developing muscle cells and reveals how perturbations to bioelectric signaling in the neuromuscular system_may contribute to developmental myopathies. Moreover, this work underscores a critical motif of signal propagation between organ systems and highlights the pivotal role played by GJ communication in coordinating bioelectric signaling during development.
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7
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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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8
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Zawieja SD, Pea GA, Broyhill SE, Bromert KH, Norton CE, Kim HJ, Li M, Castorena-Gonzalez JA, Drumm BT, Davis MJ. Lymphatic muscle cells are the innate pacemaker cells regulating mouse lymphatic collecting vessel contractions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554619. [PMID: 37662284 PMCID: PMC10473772 DOI: 10.1101/2023.08.24.554619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Collecting lymphatic vessels (cLVs) exhibit spontaneous contractions with a pressure-dependent frequency, but the identity of the lymphatic pacemaker cell is still debated. By analogy to pacemakers in the GI and lower urinary tracts, proposed cLV pacemaker cells include interstitial cells of Cajal like cells (ICLC), pericytes, as well as the lymphatic muscle (LMCs) cells themselves. Here we tested the extent to which these cell types are invested into the mouse cLV wall and if any cell type exhibited morphological and functional processes characteristic of pacemaker cells: a contiguous network; spontaneous Ca2+ transients; and depolarization-induced propagated contractions. We employed inducible Cre (iCre) mouse models routinely used to target these specific cell populations including: c-kitCreERT2 to target ICLC; PdgfrβCreERT2 to target pericytes; PdgfrαCreER™ to target CD34+ adventitial fibroblast-like cells or ICLC; and Myh11CreERT2 to target LMCs. These specific inducible Cre lines were crossed to the fluorescent reporter ROSA26mT/mG, the genetically encoded Ca2+ sensor GCaMP6f, and the light-activated cation channel rhodopsin2 (ChR2). c-KitCreERT2 labeled both a sparse population of LECs and round adventitial cells that responded to the mast cell activator compound 48-80. PdgfrβCreERT2 drove recombination in both adventitial cells and LMCs, limiting its power to discriminate a pericyte specific population. PdgfrαCreER™ labeled a large population of interconnected, oak leaf-shaped cells primarily along the adventitial surface of the vessel. Titrated induction of the smooth muscle-specific Myh11CreERT2 revealed a LMC population with heterogeneous morphology. Only LMCs consistently, but heterogeneously, displayed spontaneous Ca2+ events during the diastolic period of the contraction cycle, and whose frequency was modulated in a pressure-dependent manner. Optogenetic depolarization through the expression of ChR2 by Myh11CreERT2, but not PdgfrαCreER™ or c-KitCreERT2, resulted in a propagated contraction. These findings support the conclusion that LMCs, or a subset of LMCs, are responsible for mouse cLV pacemaking.
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Affiliation(s)
- S D Zawieja
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | - G A Pea
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | - S E Broyhill
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | - K H Bromert
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | - C E Norton
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | - H J Kim
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | - M Li
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
| | | | - B T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, A91 K584, Ireland
| | - M J Davis
- Dept. of Medical Pharmacology & Physiology, University of Missouri, Columbia, Missouri
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Gallego C, Jaracz-Ros A, Laganà M, Mercier-Nomé F, Domenichini S, Fumagalli A, Roingeard P, Herfs M, Pidoux G, Bachelerie F, Schlecht-Louf G. Reprogramming of connexin landscape fosters fast gap junction intercellular communication in human papillomavirus-infected epithelia. Front Cell Infect Microbiol 2023; 13:1138232. [PMID: 37260709 PMCID: PMC10228504 DOI: 10.3389/fcimb.2023.1138232] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 04/26/2023] [Indexed: 06/02/2023] Open
Abstract
Human papillomaviruses (HPVs) are highly prevalent commensal viruses that require epithelial stratification to complete their replicative cycle. While HPV infections are most often asymptomatic, certain HPV types can cause lesions, that are usually benign. In rare cases, these infections may progress to non-replicative viral cycles associated with high HPV oncogene expression promoting cell transformation, and eventually cancer when not cleared by host responses. While the consequences of HPV-induced transformation on keratinocytes have been extensively explored, the impact of viral replication on epithelial homeostasis remains largely unexplored. Gap junction intercellular communication (GJIC) is critical for stratified epithelium integrity and function. This process is ensured by a family of proteins named connexins (Cxs), including 8 isoforms that are expressed in stratified squamous epithelia. GJIC was reported to be impaired in HPV-transformed cells, which was attributed to the decreased expression of the Cx43 isoform. However, it remains unknown whether and how HPV replication might impact on the expression of Cx isoforms and GJIC in stratified squamous epithelia. To address this question, we have used 3D-epithelial cell cultures (3D-EpCs), the only model supporting the productive HPV life cycle. We report a transcriptional downregulation of most epithelial Cx isoforms except Cx45 in HPV-replicating epithelia. At the protein level, HPV replication results in a reduction of Cx43 expression while that of Cx45 increases and displays a topological shift toward the cell membrane. To quantify GJIC, we pioneered quantitative gap-fluorescence loss in photobleaching (FLIP) assay in 3D-EpCs, which allowed us to show that the reprogramming of Cx landscape in response to HPV replication translates into accelerated GJIC in living epithelia. Supporting the pathophysiological relevance of our observations, the HPV-associated Cx43 and Cx45 expression pattern was confirmed in human cervical biopsies harboring HPV. In conclusion, the reprogramming of Cx expression and distribution in HPV-replicating epithelia fosters accelerated GJIC, which may participate in epithelial homeostasis and host immunosurveillance.
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Affiliation(s)
- Carmen Gallego
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Agnieszka Jaracz-Ros
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Marta Laganà
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Françoise Mercier-Nomé
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
- US31-UMS3679-Plateforme PHIC, Ingénierie et Plateformes au Service de l’Innovation Thérapeutique (IPSIT), INSERM, CNRS, Université Paris-Saclay, Orsay, France
| | - Séverine Domenichini
- UMS-IPSIT Plateforme MIPSIT, Université Paris-Saclay, CNRS, Inserm, Ingénierie et Plateformes au Service de l’Innovation Thérapeutique, Orsay, France
| | - Amos Fumagalli
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Philippe Roingeard
- INSERM U1259, Université de Tours et CHRU de Tours & Plateforme IBiSA des Microscopies, PPF ASB, CHRU de Tours, Tours, France
| | - Michael Herfs
- Laboratory of Experimental Pathology, GIGA-Cancer, University of Liège, Liège, Belgium
| | | | - Françoise Bachelerie
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Géraldine Schlecht-Louf
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
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10
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Abrams CK. Mechanisms of Diseases Associated with Mutation in GJC2/Connexin 47. Biomolecules 2023; 13:biom13040712. [PMID: 37189458 DOI: 10.3390/biom13040712] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
Connexins are members of a family of integral membrane proteins that provide a pathway for both electrical and metabolic coupling between cells. Astroglia express connexin 30 (Cx30)-GJB6 and Cx43-GJA1, while oligodendroglia express Cx29/Cx31.3-GJC3, Cx32-GJB1, and Cx47-GJC2. Connexins organize into hexameric hemichannels (homomeric if all subunits are identical or heteromeric if one or more differs). Hemichannels from one cell then form cell-cell channels with a hemichannel from an apposed cell. (These are termed homotypic if the hemichannels are identical and heterotypic if the hemichannels differ). Oligodendrocytes couple to each other through Cx32/Cx32 or Cx47/Cx47 homotypic channels and they couple to astrocytes via Cx32/Cx30 or Cx47/Cx43 heterotypic channels. Astrocytes couple via Cx30/Cx30 and Cx43/Cx43 homotypic channels. Though Cx32 and Cx47 may be expressed in the same cells, all available data suggest that Cx32 and Cx47 cannot interact heteromerically. Animal models wherein one or in some cases two different CNS glial connexins have been deleted have helped to clarify the role of these molecules in CNS function. Mutations in a number of different CNS glial connexin genes cause human disease. Mutations in GJC2 lead to three distinct phenotypes, Pelizaeus Merzbacher like disease, hereditary spastic paraparesis (SPG44) and subclinical leukodystrophy.
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Affiliation(s)
- Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, USA
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11
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Silic MR, Zhang G. Bioelectricity in Developmental Patterning and Size Control: Evidence and Genetically Encoded Tools in the Zebrafish Model. Cells 2023; 12:cells12081148. [PMID: 37190057 DOI: 10.3390/cells12081148] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/03/2023] [Accepted: 04/10/2023] [Indexed: 05/17/2023] Open
Abstract
Developmental patterning is essential for regulating cellular events such as axial patterning, segmentation, tissue formation, and organ size determination during embryogenesis. Understanding the patterning mechanisms remains a central challenge and fundamental interest in developmental biology. Ion-channel-regulated bioelectric signals have emerged as a player of the patterning mechanism, which may interact with morphogens. Evidence from multiple model organisms reveals the roles of bioelectricity in embryonic development, regeneration, and cancers. The Zebrafish model is the second most used vertebrate model, next to the mouse model. The zebrafish model has great potential for elucidating the functions of bioelectricity due to many advantages such as external development, transparent early embryogenesis, and tractable genetics. Here, we review genetic evidence from zebrafish mutants with fin-size and pigment changes related to ion channels and bioelectricity. In addition, we review the cell membrane voltage reporting and chemogenetic tools that have already been used or have great potential to be implemented in zebrafish models. Finally, new perspectives and opportunities for bioelectricity research with zebrafish are discussed.
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Affiliation(s)
- Martin R Silic
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
| | - GuangJun Zhang
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
- Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute for Inflammation, Immunology and Infectious Diseases (PI4D), Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute for Integrative Neuroscience, Purdue University, 625 Harrison Street, West Lafayette, IN 47907, USA
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12
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Mao L, Wang Y, An L, Zeng B, Wang Y, Frishman D, Liu M, Chen Y, Tang W, Xu H. Molecular Mechanisms and Clinical Phenotypes of GJB2 Missense Variants. BIOLOGY 2023; 12:biology12040505. [PMID: 37106706 PMCID: PMC10135792 DOI: 10.3390/biology12040505] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 03/29/2023]
Abstract
The GJB2 gene is the most common gene responsible for hearing loss (HL) worldwide, and missense variants are the most abundant type. GJB2 pathogenic missense variants cause nonsyndromic HL (autosomal recessive and dominant) and syndromic HL combined with skin diseases. However, the mechanism by which these different missense variants cause the different phenotypes is unknown. Over 2/3 of the GJB2 missense variants have yet to be functionally studied and are currently classified as variants of uncertain significance (VUS). Based on these functionally determined missense variants, we reviewed the clinical phenotypes and investigated the molecular mechanisms that affected hemichannel and gap junction functions, including connexin biosynthesis, trafficking, oligomerization into connexons, permeability, and interactions between other coexpressed connexins. We predict that all possible GJB2 missense variants will be described in the future by deep mutational scanning technology and optimizing computational models. Therefore, the mechanisms by which different missense variants cause different phenotypes will be fully elucidated.
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Affiliation(s)
- Lu Mao
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou 450052, China
| | - Yueqiang Wang
- Basecare Medical Device Co., Ltd., Suzhou 215000, China
| | - Lei An
- Translational Medicine Center, Huaihe Hospital of Henan University, Kaifeng 475000, China
| | - Beiping Zeng
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou 450052, China
| | - Yanyan Wang
- The Research and Application Center of Precision Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, China
| | - Dmitrij Frishman
- Wissenschaftszentrum Weihenstephan, Technische Universitaet Muenchen, Am Staudengarten 2, 85354 Freising, Germany
| | - Mengli Liu
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou 450052, China
| | - Yanyu Chen
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou 450052, China
| | - Wenxue Tang
- The Research and Application Center of Precision Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, China
| | - Hongen Xu
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou 450052, China
- The Research and Application Center of Precision Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, China
- Correspondence:
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13
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Ortiz J, Bobkov YV, DeBiasse MB, Mitchell DG, Edgar A, Martindale MQ, Moss AG, Babonis LS, Ryan JF. Independent Innexin Radiation Shaped Signaling in Ctenophores. Mol Biol Evol 2023; 40:7026321. [PMID: 36740225 PMCID: PMC9949713 DOI: 10.1093/molbev/msad025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/30/2022] [Accepted: 01/25/2023] [Indexed: 02/07/2023] Open
Abstract
Innexins facilitate cell-cell communication by forming gap junctions or nonjunctional hemichannels, which play important roles in metabolic, chemical, ionic, and electrical coupling. The lack of knowledge regarding the evolution and role of these channels in ctenophores (comb jellies), the likely sister group to the rest of animals, represents a substantial gap in our understanding of the evolution of intercellular communication in animals. Here, we identify and phylogenetically characterize the complete set of innexins of four ctenophores: Mnemiopsis leidyi, Hormiphora californensis, Pleurobrachia bachei, and Beroe ovata. Our phylogenetic analyses suggest that ctenophore innexins diversified independently from those of other animals and were established early in the emergence of ctenophores. We identified a four-innexin genomic cluster, which was present in the last common ancestor of these four species and has been largely maintained in these lineages. Evidence from correlated spatial and temporal gene expression of the M. leidyi innexin cluster suggests that this cluster has been maintained due to constraints related to gene regulation. We describe the basic electrophysiological properties of putative ctenophore hemichannels from muscle cells using intracellular recording techniques, showing substantial overlap with the properties of bilaterian innexin channels. Together, our results suggest that the last common ancestor of animals had gap junctional channels also capable of forming functional innexin hemichannels, and that innexin genes have independently evolved in major lineages throughout Metazoa.
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Affiliation(s)
| | | | - Melissa B DeBiasse
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL, USA,School of Natural Sciences, University of California Merced, Merced, CA, USA
| | - Dorothy G Mitchell
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL, USA,Department of Biology, University of Florida, Gainesville, FL, USA
| | - Allison Edgar
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL, USA
| | - Mark Q Martindale
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL, USA,Department of Biology, University of Florida, Gainesville, FL, USA
| | - Anthony G Moss
- Biological Sciences Department, Auburn University, Auburn, AL, USA
| | - Leslie S Babonis
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL, USA,Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
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14
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From the Catastrophic Objective Irreproducibility of Cancer Research and Unavoidable Failures of Molecular Targeted Therapies to the Sparkling Hope of Supramolecular Targeted Strategies. Int J Mol Sci 2023; 24:ijms24032796. [PMID: 36769134 PMCID: PMC9917659 DOI: 10.3390/ijms24032796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/22/2023] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
The unprecedented non-reproducibility of the results published in the field of cancer research has recently come under the spotlight. In this short review, we try to highlight some general principles in the organization and evolution of cancerous tumors, which objectively lead to their enormous variability and, consequently, the irreproducibility of the results of their investigation. This heterogeneity is also extremely unfavorable for the effective use of molecularly targeted medicine. Against the seemingly comprehensive background of this heterogeneity, we single out two supramolecular characteristics common to all tumors: the clustered nature of tumor interactions with their microenvironment and the formation of biomolecular condensates with tumor-specific distinctive features. We suggest that these features can form the basis of strategies for tumor-specific supramolecular targeted therapies.
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15
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The Multifaceted Role of Connexins in Tumor Microenvironment Initiation and Maintenance. BIOLOGY 2023; 12:biology12020204. [PMID: 36829482 PMCID: PMC9953436 DOI: 10.3390/biology12020204] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/19/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023]
Abstract
Today's research on the processes of carcinogenesis and the vital activity of tumor tissues implies more attention be paid to constituents of the tumor microenvironment and their interactions. These interactions between cells in the tumor microenvironment can be mediated via different types of protein junctions. Connexins are one of the major contributors to intercellular communication. They form the gap junctions responsible for the transfer of ions, metabolites, peptides, miRNA, etc., between neighboring tumor cells as well as between tumor and stromal cells. Connexin hemichannels mediate purinergic signaling and bidirectional molecular transport with the extracellular environment. Additionally, connexins have been reported to localize in tumor-derived exosomes and facilitate the release of their cargo. A large body of evidence implies that the role of connexins in cancer is multifaceted. The pro- or anti-tumorigenic properties of connexins are determined by their abundance, localization, and functionality as well as their channel assembly and non-channel functions. In this review, we have summarized the data on the contribution of connexins to the formation of the tumor microenvironment and to cancer initiation and progression.
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16
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Understanding the Role of ATP Release through Connexins Hemichannels during Neurulation. Int J Mol Sci 2023; 24:ijms24032159. [PMID: 36768481 PMCID: PMC9916920 DOI: 10.3390/ijms24032159] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 01/25/2023] Open
Abstract
Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD+; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis. Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation.
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17
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Pun R, Kim MH, North BJ. Role of Connexin 43 phosphorylation on Serine-368 by PKC in cardiac function and disease. Front Cardiovasc Med 2023; 9:1080131. [PMID: 36712244 PMCID: PMC9877470 DOI: 10.3389/fcvm.2022.1080131] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/19/2022] [Indexed: 01/13/2023] Open
Abstract
Intercellular communication mediated by gap junction channels and hemichannels composed of Connexin 43 (Cx43) is vital for the propagation of electrical impulses through cardiomyocytes. The carboxyl terminal tail of Cx43 undergoes various post-translational modifications including phosphorylation of its Serine-368 (S368) residue. Protein Kinase C isozymes directly phosphorylate S368 to alter Cx43 function and stability through inducing conformational changes affecting channel permeability or promoting internalization and degradation to reduce intercellular communication between cardiomyocytes. Recent studies have implicated this PKC/Cx43-pS368 circuit in several cardiac-associated diseases. In this review, we describe the molecular and cellular basis of PKC-mediated Cx43 phosphorylation and discuss the implications of Cx43 S368 phosphorylation in the context of various cardiac diseases, such as cardiomyopathy, as well as the therapeutic potential of targeting this pathway.
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Affiliation(s)
- Renju Pun
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
| | - Michael H. Kim
- CHI Health Heart Institute, School of Medicine, Creighton University, Omaha, NE, United States
| | - Brian J. North
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States,*Correspondence: Brian J. North,
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18
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Abbott AC, García IE, Villanelo F, Flores-Muñoz C, Ceriani R, Maripillán J, Novoa-Molina J, Figueroa-Cares C, Pérez-Acle T, Sáez JC, Sánchez HA, Martínez AD. Expression of KID syndromic mutation Cx26S17F produces hyperactive hemichannels in supporting cells of the organ of Corti. Front Cell Dev Biol 2023; 10:1071202. [PMID: 36699003 PMCID: PMC9868548 DOI: 10.3389/fcell.2022.1071202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
Some mutations in gap junction protein Connexin 26 (Cx26) lead to syndromic deafness, where hearing impairment is associated with skin disease, like in Keratitis Ichthyosis Deafness (KID) syndrome. This condition has been linked to hyperactivity of connexin hemichannels but this has never been demonstrated in cochlear tissue. Moreover, some KID mutants, like Cx26S17F, form hyperactive HCs only when co-expressed with other wild-type connexins. In this work, we evaluated the functional consequences of expressing a KID syndromic mutation, Cx26S17F, in the transgenic mouse cochlea and whether co-expression of Cx26S17F and Cx30 leads to the formation of hyperactive HCs. Indeed, we found that cochlear explants from a constitutive knock-in Cx26S17F mouse or conditional in vitro cochlear expression of Cx26S17F produces hyperactive HCs in supporting cells of the organ of Corti. These conditions also produce loss of hair cells stereocilia. In supporting cells, we found high co-localization between Cx26S17F and Cx30. The functional properties of HCs formed in cells co-expressing Cx26S17F and Cx30 were also studied in oocytes and HeLa cells. Under the recording conditions used in this study Cx26S17F did not form functional HCs and GJCs, but cells co-expressing Cx26S17F and Cx30 present hyperactive HCs insensitive to HCs blockers, Ca2+ and La3+, resulting in more Ca2+ influx and cellular damage. Molecular dynamic analysis of putative heteromeric HC formed by Cx26S17F and Cx30 presents alterations in extracellular Ca2+ binding sites. These results support that in KID syndrome, hyperactive HCs are formed by the interaction between Cx26S17F and Cx30 in supporting cells probably causing damage to hair cells associated to deafness.
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Affiliation(s)
- Ana C. Abbott
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,Facultad de Medicina Veterinaria y Agronomía, Instituto de Ciencias Naturales, Universidad de las Américas, Viña del Mar, Chile
| | - Isaac E. García
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,Laboratorio de Fisiología Molecular y Biofísica, Facultad de Odontología, Universidad de Valparaíso, Valparaíso, Chile,Centro de Investigaciones en Ciencias Odontológicas y Médicas, CICOM, Universidad de Valparaíso, Valparaíso, Chile
| | - Felipe Villanelo
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile,Computational Biology Lab, Centro Basal Ciencia & Vida, Universidad San Sebastián, Santiago, Chile
| | - Carolina Flores-Muñoz
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ricardo Ceriani
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,Escuela de Química y Farmacia, Facultad de Farmacia, Universidad de Valparaíso, Valparaíso, Chile
| | - Jaime Maripillán
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Joel Novoa-Molina
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Cindel Figueroa-Cares
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Tomas Pérez-Acle
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile,Computational Biology Lab, Centro Basal Ciencia & Vida, Universidad San Sebastián, Santiago, Chile
| | - Juan C. Sáez
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Helmuth A. Sánchez
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,*Correspondence: Helmuth A. Sánchez, ; Agustín D. Martínez,
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,*Correspondence: Helmuth A. Sánchez, ; Agustín D. Martínez,
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19
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Baracaldo-Santamaría D, Corrales-Hernández MG, Ortiz-Vergara MC, Cormane-Alfaro V, Luque-Bernal RM, Calderon-Ospina CA, Cediel-Becerra JF. Connexins and Pannexins: Important Players in Neurodevelopment, Neurological Diseases, and Potential Therapeutics. Biomedicines 2022; 10:2237. [PMID: 36140338 PMCID: PMC9496069 DOI: 10.3390/biomedicines10092237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
Cell-to-cell communication is essential for proper embryonic development and its dysfunction may lead to disease. Recent research has drawn attention to a new group of molecules called connexins (Cxs) and pannexins (Panxs). Cxs have been described for more than forty years as pivotal regulators of embryogenesis; however, the exact mechanism by which they provide this regulation has not been clearly elucidated. Consequently, Cxs and Panxs have been linked to congenital neurodegenerative diseases such as Charcot-Marie-Tooth disease and, more recently, chronic hemichannel opening has been associated with adult neurodegenerative diseases (e.g., Alzheimer's disease). Cell-to-cell communication via gap junctions formed by hexameric assemblies of Cxs, known as connexons, is believed to be a crucial component in developmental regulation. As for Panxs, despite being topologically similar to Cxs, they predominantly seem to form channels connecting the cytoplasm to the extracellular space and, despite recent research into Panx1 (Pannexin 1) expression in different regions of the brain during the embryonic phase, it has been studied to a lesser degree. When it comes to the nervous system, Cxs and Panxs play an important role in early stages of neuronal development with a wide span of action ranging from cellular migration during early stages to neuronal differentiation and system circuitry formation. In this review, we describe the most recent available evidence regarding the molecular and structural aspects of Cx and Panx channels, their role in neurodevelopment, congenital and adult neurological diseases, and finally propose how pharmacological modulation of these channels could modify the pathogenesis of some diseases.
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Affiliation(s)
- Daniela Baracaldo-Santamaría
- Pharmacology Unit, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
| | - María Gabriela Corrales-Hernández
- Pharmacology Unit, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
| | - Maria Camila Ortiz-Vergara
- Pharmacology Unit, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
| | - Valeria Cormane-Alfaro
- Pharmacology Unit, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
| | - Ricardo-Miguel Luque-Bernal
- Anatomy and Embriology Units, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
| | - Carlos-Alberto Calderon-Ospina
- Pharmacology Unit, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
- GENIUROS Research Group, Center for Research in Genetics and Genomics (CIGGUR), School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
| | - Juan-Fernando Cediel-Becerra
- Histology and Embryology Unit, Department of Biomedical Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia
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20
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Fang JS, Burt JM. Connexin37 Regulates Cell Cycle in the Vasculature. J Vasc Res 2022; 60:73-86. [PMID: 36067749 DOI: 10.1159/000525619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/08/2022] [Indexed: 11/19/2022] Open
Abstract
Control of vascular cell growth responses is critical for development and maintenance of a healthy vasculature. Connexins - the proteins comprising gap junction channels - are key regulators of cell growth in diseases such as cancer, but their involvement in controlling cell growth in the vasculature is less well appreciated. Connexin37 (Cx37) is one of four connexin isotypes expressed in the vessel wall. Its primary role in blood vessels relies on its unique ability to transduce flow-sensitive signals into changes in cell cycle status of endothelial (and perhaps, mural) cells. Here, we review available evidence for Cx37's role in the regulation of vascular growth, vessel organization, and vascular tone in healthy and diseased vasculature. We propose a novel mechanism whereby Cx37 accomplishes this with a phosphorylation-dependent transition between closed (growth-suppressive) and multiple open (growth-permissive) channel conformations that result from interactions of the C-terminus with cell-cycle regulators to limit or support cell cycle progression. Lastly, we discuss Cx37 and its downstream signaling as a novel potential target in the treatment of cardiovascular disease, and we address outstanding research questions that still challenge the development of such therapies.
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Affiliation(s)
- Jennifer S Fang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, USA
| | - Janis M Burt
- Department of Physiology, University of Arizona, Tucson, Arizona, USA
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21
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Lukowicz-Bedford RM, Farnsworth DR, Miller AC. Connexinplexity: the spatial and temporal expression of connexin genes during vertebrate organogenesis. G3 (BETHESDA, MD.) 2022; 12:jkac062. [PMID: 35325106 PMCID: PMC9073686 DOI: 10.1093/g3journal/jkac062] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/24/2022] [Indexed: 11/28/2022]
Abstract
Animal development requires coordinated communication between cells. The Connexin family of proteins is a major contributor to intercellular communication in vertebrates by forming gap junction channels that facilitate the movement of ions, small molecules, and metabolites between cells. Additionally, individual hemichannels can provide a conduit to the extracellular space for paracrine and autocrine signaling. Connexin-mediated communication is widely used in epithelial, neural, and vascular development and homeostasis, and most tissues likely use this form of communication. In fact, Connexin disruptions are of major clinical significance contributing to disorders developing from all major germ layers. Despite the fact that Connexins serve as an essential mode of cellular communication, the temporal and cell-type-specific expression patterns of connexin genes remain unknown in vertebrates. A major challenge is the large and complex connexin gene family. To overcome this barrier, we determined the expression of all connexins in zebrafish using single-cell RNA-sequencing of entire animals across several stages of organogenesis. Our analysis of expression patterns has revealed that few connexins are broadly expressed, but rather, most are expressed in tissue- or cell-type-specific patterns. Additionally, most tissues possess a unique combinatorial signature of connexin expression with dynamic temporal changes across the organism, tissue, and cell. Our analysis has identified new patterns for well-known connexins and assigned spatial and temporal expression to genes with no-existing information. We provide a field guide relating zebrafish and human connexin genes as a critical step toward understanding how Connexins contribute to cellular communication and development throughout vertebrate organogenesis.
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Affiliation(s)
| | - Dylan R Farnsworth
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - Adam C Miller
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, OR 97403, USA
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22
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Ishibashi M, Keung J, Morgans CW, Aicher SA, Carroll JR, Singer JH, Jia L, Li W, Fahrenfort I, Ribelayga CP, Massey SC. Analysis of rod/cone gap junctions from the reconstruction of mouse photoreceptor terminals. eLife 2022; 11:73039. [PMID: 35471186 PMCID: PMC9170248 DOI: 10.7554/elife.73039] [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: 08/13/2021] [Accepted: 04/25/2022] [Indexed: 12/14/2022] Open
Abstract
Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization, and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions. Here, we reconstruct gap junctions between photoreceptors in the mouse retina using serial blockface-scanning electron microscopy, focused ion beam-scanning electron microscopy, and confocal microscopy for the gap junction protein Cx36. An exuberant spray of fine telodendria extends from each cone pedicle (including blue cones) to contact 40-50 nearby rod spherules at sites of Cx36 labeling, with approximately 50 Cx36 clusters per cone pedicle and 2-3 per rod spherule. We were unable to detect rod/rod or cone/cone coupling. Thus, rod/cone coupling accounts for nearly all gap junctions between photoreceptors. We estimate a mean of 86 Cx36 channels per rod/cone pair, which may provide a maximum conductance of ~1200 pS, if all gap junction channels were open. This is comparable to the maximum conductance previously measured between rod/cone pairs in the presence of a dopamine antagonist to activate Cx36, suggesting that the open probability of gap junction channels can approach 100% under certain conditions.
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Affiliation(s)
- Munenori Ishibashi
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Joyce Keung
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Catherine W Morgans
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, United States
| | - Sue A Aicher
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, United States
| | - James R Carroll
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, United States
| | - Joshua H Singer
- Department of Biology, University of Maryland, College Park, College Park, United States
| | - Li Jia
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Wei Li
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Iris Fahrenfort
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Christophe P Ribelayga
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
| | - Stephen C Massey
- Richard Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas at Houston, Houston, United States
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Generation and Characterization of an Inducible Cx43 Overexpression System in Mouse Embryonic Stem Cells. Cells 2022; 11:cells11040694. [PMID: 35203340 PMCID: PMC8869955 DOI: 10.3390/cells11040694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 11/17/2022] Open
Abstract
Connexins (Cx) are a large family of membrane proteins that can form intercellular connections, so-called gap junctions between adjacent cells. Cx43 is widely expressed in mammals and has a variety of different functions, such as the propagation of electrical conduction in the cardiac ventricle. Despite Cx43 knockout models, many questions regarding the biology of Cx43 in health and disease remain unanswered. Herein we report the establishment of a Cre-inducible Cx43 overexpression system in murine embryonic stem (ES) cells. This enables the investigation of the impact of Cx43 overexpression in somatic cells. We utilized a double reporter system to label Cx43-overexpressing cells via mCherry fluorescence and exogenous Cx43 via fusion with P2A peptide to visualize its distribution pattern. We proved the functionality of our systems in ES cells, HeLa cells, and 3T3-fibroblasts and demonstrated the formation of functional gap junctions based on dye diffusion and FRAP experiments. In addition, Cx43-overexpressing ES cells could be differentiated into viable cardiomyocytes, as shown by the formation of cross striation and spontaneous beating. Analysis revealed faster and more rhythmic beating of Cx43-overexpressing cell clusters. Thus, our Cx43 overexpression systems enable the investigation of Cx43 biology and function in cardiomyocytes and other somatic cells.
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Function and Plasticity of Electrical Synapses in the Mammalian Brain: Role of Non-Junctional Mechanisms. BIOLOGY 2022; 11:biology11010081. [PMID: 35053079 PMCID: PMC8773336 DOI: 10.3390/biology11010081] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 01/27/2023]
Abstract
Simple Summary Relevant brain functions, such as perception, organization of behavior, and cognitive processes, are the outcome of information processing by neural circuits. Within these circuits, communication between neurons mainly relies on two modalities of synaptic transmission: chemical and electrical. Moreover, changes in the strength of these connections, aka synaptic plasticity, are believed to underlie processes of learning and memory, and its dysfunction has been suggested to underlie a variety of neurological disorders. While the relevance of chemical transmission and its plastic changes are known in great detail, analogous mechanisms and functional impact of their electrical counterparts were only recently acknowledged. In this article, we review the basic physical principles behind electrical transmission between neurons, the plethora of functional operations supported by this modality of neuron-to-neuron communication, as well as the basic principles of plasticity at these synapses. Abstract Electrical transmission between neurons is largely mediated by gap junctions. These junctions allow the direct flow of electric current between neurons, and in mammals, they are mostly composed of the protein connexin36. Circuits of electrically coupled neurons are widespread in these animals. Plus, experimental and theoretical evidence supports the notion that, beyond synchronicity, these circuits are able to perform sophisticated operations such as lateral excitation and inhibition, noise reduction, as well as the ability to selectively respond upon coincident excitatory inputs. Although once considered stereotyped and unmodifiable, we now know that electrical synapses are subject to modulation and, by reconfiguring neural circuits, these modulations can alter relevant operations. The strength of electrical synapses depends on the gap junction resistance, as well as on its functional interaction with the electrophysiological properties of coupled neurons. In particular, voltage and ligand gated channels of the non-synaptic membrane critically determine the efficacy of transmission at these contacts. Consistently, modulatory actions on these channels have been shown to represent relevant mechanisms of plasticity of electrical synaptic transmission. Here, we review recent evidence on the regulation of electrical synapses of mammals, the underlying molecular mechanisms, and the possible ways in which they affect circuit function.
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25
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Laird DW, Lampe PD. Cellular mechanisms of connexin-based inherited diseases. Trends Cell Biol 2022; 32:58-69. [PMID: 34429228 PMCID: PMC8688313 DOI: 10.1016/j.tcb.2021.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 01/03/2023]
Abstract
The 21-member connexin gene family exhibits distinct tissue expression patterns that can cause a diverse array of over 30 inherited connexin-linked diseases ranging from deafness to skin defects and blindness. Intriguingly, germline mutations can cause disease in one tissue while other tissues that abundantly express the mutant connexin remain disease free, highlighting the importance of the cellular context of mutant expression. Modeling connexin pathologies in genetically modified mice and tissue-relevant cells has informed extensively on no less than a dozen gain- and loss-of-function mechanisms that underpin disease. This review focuses on how a deeper molecular understanding of the over 930 mutations in 11 connexin-encoding genes is foundational for creating a framework for therapeutic interventions.
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Affiliation(s)
- Dale W. Laird
- Departments of Anatomy and Cell Biology, and Physiology and Pharmacology, University of Western Ontario, London, ON, CANADA
| | - Paul D. Lampe
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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26
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Appukuttan S, Brain KL, Manchanda R. Effect of Variations in Gap Junctional Coupling on the Frequency of Oscillatory Action Potentials in a Smooth Muscle Syncytium. Front Physiol 2021; 12:655225. [PMID: 34658901 PMCID: PMC8517141 DOI: 10.3389/fphys.2021.655225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Gap junctions provide pathways for intercellular communication between adjacent cells, allowing exchange of ions and small molecules. Based on the constituent protein subunits, gap junctions are classified into different subtypes varying in their properties such as unitary conductances, sensitivity to transjunctional voltage, and gating kinetics. Gap junctions couple cells electrically, and therefore the electrical activity originating in one cell can affect and modulate the electrical activity in adjacent cells. Action potentials can propagate through networks of such electrically coupled cells, and this spread is influenced by the nature of gap junctional coupling. Our study aims to computationally explore the effect of differences in gap junctional properties on oscillating action potentials in electrically coupled tissues. Further, we also explore variations in the biophysical environment by altering the size of the syncytium, the location of the pacemaking cell, as well as the occurrence of multiple pacemaking cells within the same syncytium. Our simulation results suggest that the frequency of oscillations is governed by the extent of coupling between cells and the gating kinetics of different gap junction subtypes. The location of pacemaking cells is found to alter the syncytial behavior, and when multiple oscillators are present, there exists an interplay between the oscillator frequency and their relative location within the syncytium. Such variations in the frequency of oscillations can have important implications for the physiological functioning of syncytial tissues.
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Affiliation(s)
- Shailesh Appukuttan
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Keith L. Brain
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rohit Manchanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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27
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King DR, Sedovy MW, Leng X, Xue J, Lamouille S, Koval M, Isakson BE, Johnstone SR. Mechanisms of Connexin Regulating Peptides. Int J Mol Sci 2021; 22:ijms221910186. [PMID: 34638526 PMCID: PMC8507914 DOI: 10.3390/ijms221910186] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 12/22/2022] Open
Abstract
Gap junctions (GJ) and connexins play integral roles in cellular physiology and have been found to be involved in multiple pathophysiological states from cancer to cardiovascular disease. Studies over the last 60 years have demonstrated the utility of altering GJ signaling pathways in experimental models, which has led to them being attractive targets for therapeutic intervention. A number of different mechanisms have been proposed to regulate GJ signaling, including channel blocking, enhancing channel open state, and disrupting protein-protein interactions. The primary mechanism for this has been through the design of numerous peptides as therapeutics, that are either currently in early development or are in various stages of clinical trials. Despite over 25 years of research into connexin targeting peptides, the overall mechanisms of action are still poorly understood. In this overview, we discuss published connexin targeting peptides, their reported mechanisms of action, and the potential for these molecules in the treatment of disease.
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Affiliation(s)
- D. Ryan King
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, VA 24016, USA; (D.R.K.); (M.W.S.); (X.L.); (S.L.)
| | - Meghan W. Sedovy
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, VA 24016, USA; (D.R.K.); (M.W.S.); (X.L.); (S.L.)
- Translational Biology, Medicine, and Health Graduate Program, Virginia Tech, Blacksburg, VA 24061, USA
| | - Xinyan Leng
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, VA 24016, USA; (D.R.K.); (M.W.S.); (X.L.); (S.L.)
| | - Jianxiang Xue
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; (J.X.); (B.E.I.)
| | - Samy Lamouille
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, VA 24016, USA; (D.R.K.); (M.W.S.); (X.L.); (S.L.)
- Center for Vascular and Heart Research, Virginia Tech, Roanoke, VA 24016, USA
| | - Michael Koval
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA;
| | - Brant E. Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; (J.X.); (B.E.I.)
- Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Scott R. Johnstone
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, VA 24016, USA; (D.R.K.); (M.W.S.); (X.L.); (S.L.)
- Center for Vascular and Heart Research, Virginia Tech, Roanoke, VA 24016, USA
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24060, USA
- Correspondence:
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Orellana VP, Tittarelli A, Retamal MA. Connexins in melanoma: Potential role of Cx46 in its aggressiveness. Pigment Cell Melanoma Res 2021; 34:853-868. [PMID: 33140904 DOI: 10.1111/pcmr.12945] [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] [Received: 09/07/2020] [Revised: 10/20/2020] [Accepted: 10/27/2020] [Indexed: 12/19/2022]
Abstract
Melanoma is the most aggressive skin cancer, and in metastatic advanced states, it is completely refractory to chemotherapy. Therefore, it is relevant to understand the molecular bases that rule their aggressiveness. Connexins (Cxs) are proteins that under normal physiological conditions participate in intercellular communication, via the exchange of signaling molecules between the cytoplasm and extracellular milieu and the exchange of ions/second messengers between the cytoplasm of contacting cells. These proteins have shown important roles in cancer progression, chemo- and radiotherapy resistance, and metastasis. Accordingly, Cx26 and Cx43 seem to play important roles in melanoma progression and metastasis. On the other hand, Cx46 is typically expressed in the eye lens, where it seems to be associated with oxidative stress protection in fiber lens cells. However, in the last decade, Cx46 expression has been associated with breast and brain cancers, due to its role in potentiation of both extracellular vesicle release and cancer stem cell-like properties. In this review, we analyzed a potential role of Cx46 as a new biomarker and therapeutic target in melanoma.
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Affiliation(s)
- Viviana P Orellana
- Universidad del Desarrollo. Centro de Fisiología Celular e Integrativa, Clinica Alemana Facultad de Medicina, Santiago, Chile
- Universidad del Desarrollo. Programa de Comunicación Celular en Cáncer, Clínica Alemana Facultad de Medicina, Santiago, Chile
| | - Andrés Tittarelli
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación (PIDi), Universidad Tecnológica Metropolitana (UTEM), Santiago, Chile
| | - Mauricio A Retamal
- Universidad del Desarrollo. Centro de Fisiología Celular e Integrativa, Clinica Alemana Facultad de Medicina, Santiago, Chile
- Universidad del Desarrollo. Programa de Comunicación Celular en Cáncer, Clínica Alemana Facultad de Medicina, Santiago, Chile
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29
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Unal YC, Yavuz B, Ozcivici E, Mese G. The role of connexins in breast cancer: from misregulated cell communication to aberrant intracellular signaling. Tissue Barriers 2021; 10:1962698. [PMID: 34355641 DOI: 10.1080/21688370.2021.1962698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In spite of clinical advancements and improved diagnostic techniques, breast cancers are the leading cause of cancer-associated deaths in women worldwide. Although 70% of early breast cancers can be cured, there are no efficient therapies against metastatic breast cancers. Several factors including connexins and gap junctions play roles in breast tumorigenesis. Connexins are critical for cellular processes as a linkage between connexin mutations and hereditary disorders demonstrated their importance for tissue homeostasis. Further, alterations in their expression, localization and channel activities were observed in many cancers including breast cancer. Both channel-dependent and independent functions of connexins were reported in initiation and progression of cancers. Unlike initial reports suggesting tumor suppressor functions, connexins and gap junctions have stage, context and isoform dependent effects in breast cancers similar to other cancers. In this review, we tried to describe the current understanding of connexins in tumorigenesis specifically in breast cancers.
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Affiliation(s)
- Yagmur Ceren Unal
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Busra Yavuz
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Engin Ozcivici
- Department of Bioengineering, Faculty of Engineering, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Gulistan Mese
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
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30
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Abrams CK, Flores-Obando RE, Dungan GD, Cherepanova E, Freidin MM. Investigating oligodendrocyte connexins: Heteromeric interactions between Cx32 and mutant or wild-type forms of Cx47 do not contribute to or modulate gap junction function. Glia 2021; 69:1882-1896. [PMID: 33835612 DOI: 10.1002/glia.23999] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 11/11/2022]
Abstract
Oligodendrocytes express two gap junction forming connexins, connexin 32 (Cx32) and Cx47; therefore, formation of heteromeric channels containing both Cx47 and Cx32 monomers might occur. Mutations in Cx47 cause both Pelizaeus-Merzbacher-like disease Type 1 (PMLD1) and hereditary spastic paraparesis Type 44 (SPG44) and heteromer formation between these mutants and Cx32 may contribute to the pathogenesis of these disorders. Here, we utilized electrophysiological and antibody-based techniques to examine this possibility. When cells expressing both Cx32 and Cx47 were paired with cells expressing either Cx32 or Cx47, properties were indistinguishable from those produced by cells expressing homotypic Cx32 or Cx47 channels. Similarly, pairing cells expressing both Cx32 and Cx47 with cells expressing Cx30 or Cx43 produced channels indistinguishable from heterotypic Cx32/Cx30 or Cx47/Cx43 channels, respectively. The same assessments were performed on cells expressing Cx32 and four mutant forms of Cx47 (p.I33M associated with SPG44 or p.P87S, p.Y269D or p.M283T associated with PMLD1). None of these mutants showed a functional effect on Cx32. Immunostained cells co-expressing Cx32WT (wild type) and Cx47WT showed a Pearson correlation coefficient close to zero, suggesting that any overlap was due to chance. p.Y269D showed a statistically significant negative correlation with Cx32, suggesting that Cx32 and this mutant overlap less than expected by chance. Co-immunoprecipitation of Cx32 with Cx47WT and mutants show only very low levels of co-immunoprecipitated protein. Overall, our data suggest that interactions between PMLD1 or SPG44 mutants and Cx32 gap junctions do not contribute to the pathogenesis of these disorders.
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Affiliation(s)
- Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | | | - Gabriel D Dungan
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Elina Cherepanova
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | - Mona M Freidin
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
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31
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Rode K, Langeheine M, Seeger B, Brehm R. Connexin43 in Germ Cells Seems to Be Dispensable for Murine Spermatogenesis. Int J Mol Sci 2021; 22:ijms22157924. [PMID: 34360693 PMCID: PMC8348783 DOI: 10.3390/ijms22157924] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/13/2021] [Accepted: 07/21/2021] [Indexed: 02/07/2023] Open
Abstract
Testicular Connexin43 (Cx43) connects adjacent Sertoli cells (SC) and SC to germ cells (GC) in the seminiferous epithelium and plays a crucial role in spermatogenesis. However, the distinction whether this results from impaired inter-SC communication or between GC and SC is not possible, so far. Thus, the question arises, whether a GC-specific Cx43 KO has similar effects on spermatogenesis as it is general or SC-specific KO. Using the Cre/loxP recombinase system, two conditional KO mouse lines lacking Cx43 in premeiotic (pGCCx43KO) or meiotic GC (mGCCx43KO) were generated. It was demonstrated by qRT-PCR that Cx43 mRNA was significantly decreased in adult pGCCx43KO mice, while it was also reduced in mGCCx43KO mice, yet not statistically significant. Body and testis weights, testicular histology, tubular diameter, numbers of intratubular cells and Cx43 protein synthesis and localization did not show any significant differences in semi-quantitative Western blot analysis and immunohistochemistry comparing adult male KO and WT mice of both mouse lines. Male KO mice were fertile. These results indicate that Cx43 in spermatogonia/spermatids does not seem to be essential for successful termination of spermatogenesis and fertility as it is known for Cx43 in somatic SC, but SC-GC communication might rather occur via heterotypic GJ channels.
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Affiliation(s)
- Kristina Rode
- Institute of Anatomy, University of Veterinary Medicine Foundation, 30173 Hanover, Germany; (K.R.); (M.L.)
| | - Marion Langeheine
- Institute of Anatomy, University of Veterinary Medicine Foundation, 30173 Hanover, Germany; (K.R.); (M.L.)
| | - Bettina Seeger
- Institute for Food Quality and Food Safety, University of Veterinary Medicine Foundation, 30173 Hanover, Germany;
| | - Ralph Brehm
- Institute of Anatomy, University of Veterinary Medicine Foundation, 30173 Hanover, Germany; (K.R.); (M.L.)
- Correspondence: ; Tel.: +49-511-8457215
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32
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Yue B, Haddad BG, Khan U, Chen H, Atalla M, Zhang Z, Zuckerman DM, Reichow SL, Bai D. Connexin 46 and connexin 50 gap junction channel properties are shaped by structural and dynamic features of their N-terminal domains. J Physiol 2021; 599:3313-3335. [PMID: 33876426 PMCID: PMC8249348 DOI: 10.1113/jp281339] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/12/2021] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Gap junctions formed by different connexins are expressed throughout the body and harbour unique channel properties that have not been fully defined mechanistically. Recent structural studies by cryo-electron microscopy have produced high-resolution models of the related but functionally distinct lens connexins (Cx50 and Cx46) captured in a stable open state, opening the door for structure-function comparison. Here, we conducted comparative molecular dynamics simulation and electrophysiology studies to dissect the isoform-specific differences in Cx46 and Cx50 intercellular channel function. We show that key determinants Cx46 and Cx50 gap junction channel open stability and unitary conductance are shaped by structural and dynamic features of their N-terminal domains, in particular the residue at the 9th position and differences in hydrophobic anchoring sites. The results of this study establish the open state Cx46/50 structural models as archetypes for structure-function studies targeted at elucidating the mechanism of gap junction channels and the molecular basis of disease-causing variants. ABSTRACT Connexins form intercellular communication channels, known as gap junctions (GJs), that facilitate diverse physiological roles, from long-range electrical and chemical coupling to coordinating development and nutrient exchange. GJs formed by different connexin isoforms harbour unique channel properties that have not been fully defined mechanistically. Recent structural studies on Cx46 and Cx50 defined a novel and stable open state and implicated the amino-terminal (NT) domain as a major contributor for isoform-specific functional differences between these closely related lens connexins. To better understand these differences, we constructed models corresponding to wildtype Cx50 and Cx46 GJs, NT domain swapped chimeras, and point variants at the 9th residue for comparative molecular dynamics (MD) simulation and electrophysiology studies. All constructs formed functional GJ channels, except the chimeric Cx46-50NT variant, which correlated with an introduced steric clash and increased dynamical behaviour (instability) of the NT domain observed by MD simulation. Single channel conductance correlated well with free-energy landscapes predicted by MD, but resulted in a surprisingly greater degree of effect. Additionally, we observed significant effects on transjunctional voltage-dependent gating (Vj gating) and/or open state dwell times induced by the designed NT domain variants. Together, these studies indicate intra- and inter-subunit interactions involving both hydrophobic and charged residues within the NT domains of Cx46 and Cx50 play important roles in defining GJ open state stability and single channel conductance, and establish the open state Cx46/50 structural models as archetypes for structure-function studies targeted at elucidating GJ channel mechanisms and the molecular basis of cataract-linked connexin variants.
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Affiliation(s)
- Benny Yue
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Bassam G. Haddad
- Department of Chemistry, Portland State University, Portland, OR 97201, USA
| | - Umair Khan
- Department of Chemistry, Portland State University, Portland, OR 97201, USA
| | - Honghong Chen
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Mena Atalla
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Ze Zhang
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Daniel M. Zuckerman
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR 97239, USA
| | - Steve L. Reichow
- Department of Chemistry, Portland State University, Portland, OR 97201, USA
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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Structural, functional, and mechanistic insights uncover the fundamental role of orphan connexin-62 in platelets. Blood 2021; 137:830-843. [PMID: 32822477 DOI: 10.1182/blood.2019004575] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 08/13/2020] [Indexed: 12/14/2022] Open
Abstract
Connexins oligomerise to form hexameric hemichannels in the plasma membrane that can further dock together on adjacent cells to form gap junctions and facilitate intercellular trafficking of molecules. In this study, we report the expression and function of an orphan connexin, connexin-62 (Cx62), in human and mouse (Cx57, mouse homolog) platelets. A novel mimetic peptide (62Gap27) was developed to target the second extracellular loop of Cx62, and 3-dimensional structural models predicted its interference with gap junction and hemichannel function. The ability of 62Gap27 to regulate both gap junction and hemichannel-mediated intercellular communication was observed using fluorescence recovery after photobleaching analysis and flow cytometry. Cx62 inhibition by 62Gap27 suppressed a range of agonist-stimulated platelet functions and impaired thrombosis and hemostasis. This was associated with elevated protein kinase A-dependent signaling in a cyclic adenosine monophosphate-independent manner and was not observed in Cx57-deficient mouse platelets (in which the selectivity of 62Gap27 for this connexin was also confirmed). Notably, Cx62 hemichannels were observed to function independently of Cx37 and Cx40 hemichannels. Together, our data reveal a fundamental role for a hitherto uncharacterized connexin in regulating the function of circulating cells.
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Ng XW, Chung YH, Piston DW. Intercellular Communication in the Islet of Langerhans in Health and Disease. Compr Physiol 2021; 11:2191-2225. [PMID: 34190340 DOI: 10.1002/cphy.c200026] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Blood glucose homeostasis requires proper function of pancreatic islets, which secrete insulin, glucagon, and somatostatin from the β-, α-, and δ-cells, respectively. Each islet cell type is equipped with intrinsic mechanisms for glucose sensing and secretory actions, but these intrinsic mechanisms alone cannot explain the observed secretory profiles from intact islets. Regulation of secretion involves interconnected mechanisms among and between islet cell types. Islet cells lose their normal functional signatures and secretory behaviors upon dispersal as compared to intact islets and in vivo. In dispersed islet cells, the glucose response of insulin secretion is attenuated from that seen from whole islets, coordinated oscillations in membrane potential and intracellular Ca2+ activity, as well as the two-phase insulin secretion profile, are missing, and glucagon secretion displays higher basal secretion profile and a reverse glucose-dependent response from that of intact islets. These observations highlight the critical roles of intercellular communication within the pancreatic islet, and how these communication pathways are crucial for proper hormonal and nonhormonal secretion and glucose homeostasis. Further, misregulated secretions of islet secretory products that arise from defective intercellular islet communication are implicated in diabetes. Intercellular communication within the islet environment comprises multiple mechanisms, including electrical synapses from gap junctional coupling, paracrine interactions among neighboring cells, and direct cell-to-cell contacts in the form of juxtacrine signaling. In this article, we describe the various mechanisms that contribute to proper islet function for each islet cell type and how intercellular islet communications are coordinated among the same and different islet cell types. © 2021 American Physiological Society. Compr Physiol 11:2191-2225, 2021.
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Affiliation(s)
- Xue W Ng
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - Yong H Chung
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
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35
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Ren Y, Liu Y, Luo M. Gap Junctions Between Striatal D1 Neurons and Cholinergic Interneurons. Front Cell Neurosci 2021; 15:674399. [PMID: 34168539 PMCID: PMC8217616 DOI: 10.3389/fncel.2021.674399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/29/2021] [Indexed: 01/15/2023] Open
Abstract
The striatum participates in numerous important behaviors. Its principal projection neurons use GABA and peptides as neurotransmitters and interact extensively with interneurons, including cholinergic interneurons (ChIs) that are tonically active. Dissecting the interactions between projection neurons and ChIs is important for uncovering the role and mechanisms of the striatal microcircuits. Here, by combining several optogenetic tools with cell type-specific electrophysiological recordings, we uncovered direct electrical coupling between D1-type projection neurons and ChIs, in addition to the chemical transmission between these two major cell types. Optogenetic stimulation or inhibition led to bilateral current exchanges between D1 neurons and ChIs, which can be abolished by gap junction blockers. We further confirmed the presence of gap junctions through paired electrophysiological recordings and dye microinjections. Finally, we found that activating D1 neurons promotes basal activity of ChIs via gap junctions. Collectively, these results reveal the coexistence of the chemical synapse and gap junctions between D1 neurons and ChIs, which contributes to maintaining the tonically active firing patterns of ChIs.
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Affiliation(s)
- Yuqi Ren
- School of Life Sciences, Peking University, Beijing, China.,Peking University-Tsinghua University-NIBS Joint Graduate Program, Beijing, China.,National Institute of Biological Sciences, Beijing, China
| | - Yang Liu
- School of Life Sciences, Tsinghua University, Beijing, China.,Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing, China
| | - Minmin Luo
- National Institute of Biological Sciences, Beijing, China.,Chinese Institute for Brain Research, Beijing, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Beijing, China
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Mussbacher M, Pirabe A, Brunnthaler L, Schrottmaier WC, Assinger A. Horizontal MicroRNA Transfer by Platelets - Evidence and Implications. Front Physiol 2021; 12:678362. [PMID: 34149456 PMCID: PMC8209332 DOI: 10.3389/fphys.2021.678362] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/05/2021] [Indexed: 01/03/2023] Open
Abstract
For decades, platelets have been known for their central role in hemostasis and their ability to release bioactive molecules, allowing inter-platelet communication and crosstalk with the immune system and vascular cells. However, with the detection of microRNAs in platelets and platelet-derived microvesicles (MVs), a new level of inter-cellular regulation was revealed. By shedding MVs from their plasma membrane, platelets are able to release functional microRNA complexes that are protected from plasma RNases. Upon contact with macrophages, endothelial cells and smooth muscle cells platelet microRNAs are rapidly internalized and fine-tune the functionality of the recipient cell by post-transcriptional reprogramming. Moreover, microRNA transfer by platelet MVs allows infiltration into tissues with limited cellular access such as solid tumors, thereby they not only modulate tumor progression but also provide a potential route for drug delivery. Understanding the precise mechanisms of horizontal transfer of platelet microRNAs under physiological and pathological conditions allows to design side-specific therapeutic (micro)RNA delivery systems. This review summarizes the current knowledge and the scientific evidence of horizontal microRNA transfer by platelets and platelet-derived MVs into vascular and non-vascular cells and its physiological consequences.
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Affiliation(s)
- Marion Mussbacher
- Department of Pharmacology and Toxicology, University of Graz, Graz, Austria
| | - Anita Pirabe
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Laura Brunnthaler
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Alice Assinger
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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37
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Astrocyte Networks as Therapeutic Targets in Glaucomatous Neurodegeneration. Cells 2021; 10:cells10061368. [PMID: 34199470 PMCID: PMC8228804 DOI: 10.3390/cells10061368] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/28/2021] [Accepted: 05/30/2021] [Indexed: 11/22/2022] Open
Abstract
Astrocytes are intimately involved in the response to neurodegenerative stress and have become an attractive target for the development of neuroprotective therapies. However, studies often focus on astrocytes as single-cell units. Astrocytes are densely interconnected by gap junctions that are composed primarily of the protein connexin-43 (Cx43) and can function as a broader network of cells. Such networks contribute to a number of important processes, including metabolite distribution and extracellular ionic buffering, and are likely to play an important role in the progression of neurodegenerative disease. This review will focus on the pro-degenerative and pro-survival influence of astrocyte Cx43 in disease progression, with a focus on the roles of gap junctions and hemichannels in the spread of degenerative stress. Finally, we will highlight the specific evidence for targeting these networks in the treatment of glaucomatous neurodegeneration and other optic neuropathies.
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38
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Kordowitzki P, Sokołowska G, Wasielak-Politowska M, Skowronska A, Skowronski MT. Pannexins and Connexins: Their Relevance for Oocyte Developmental Competence. Int J Mol Sci 2021; 22:ijms22115918. [PMID: 34072911 PMCID: PMC8199496 DOI: 10.3390/ijms22115918] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/23/2021] [Accepted: 05/28/2021] [Indexed: 12/29/2022] Open
Abstract
The oocyte is the major determinant of embryo developmental competence in all mammalian species. Although fundamental advances have been generated in the field of reproductive medicine and assisted reproductive technologies in the past three decades, researchers and clinicians are still trying to elucidate molecular factors and pathways, which could be pivotal for the oocyte’s developmental competence. The cell-to-cell and cell-to-matrix communications are crucial not only for oocytes but also for multicellular organisms in general. This latter mentioned communication is among others possibly due to the Connexin and Pannexin families of large-pore forming channels. Pannexins belong to a protein group of ATP-release channels, therefore of high importance for the oocyte due to its requirements of high energy supply. An increasing body of studies on Pannexins provided evidence that these channels not only play a role during physiological processes of an oocyte but also during pathological circumstances which could lead to the development of diseases or infertility. Connexins are proteins that form membrane channels and gap-junctions, and more precisely, these proteins enable the exchange of some ions and molecules, and therefore they do play a fundamental role in the communication between the oocyte and accompanying cells. Herein, the role of Pannexins and Connexins for the processes of oogenesis, folliculogenesis, oocyte maturation and fertilization will be discussed and, at the end of this review, Pannexin and Connexin related pathologies and their impact on the developmental competence of oocytes will be provided.
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Affiliation(s)
- Paweł Kordowitzki
- Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Bydgoska Street 7, 10-243 Olsztyn, Poland;
- Department of Basic and Preclinical Sciences, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Gagarina Street 7, 87-100 Torun, Poland
| | - Gabriela Sokołowska
- Department of Reproduction and Gynecological Endocrinology, Medical University of Bialystok, Jana Kilińskiego Street 1, 15-089 Białystok, Poland;
| | - Marta Wasielak-Politowska
- Center of Gynecology, Endocrinology and Reproductive Medicine—Artemida, Jagiellońska Street 78, 10-357 Olsztyn, Poland;
| | - Agnieszka Skowronska
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, Warszawska Street 30, 10-357 Olsztyn, Poland;
| | - Mariusz T. Skowronski
- Department of Basic and Preclinical Sciences, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Gagarina Street 7, 87-100 Torun, Poland
- Correspondence: ; Tel.: +48-566-112-231
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39
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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40
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Abstract
Connexins are a family of gap junction forming proteins widely expressed by mammalian cells. They assemble into hexameric hemichannels, which can either function independently or dock with opposing hemichannels on apposite cells, forming a gap junction. Pannexins are structurally related to the connexins but extensive glycosylation of these channels prevents docking to form gap junctions and they function as membrane channels. Platelets express pannexin-1 and several connexin family members (Cx37, Cx40 and Cx62). These channels are permeable to molecules up to 1,000 Daltons in molecular mass and functional studies demonstrate their role in non-vesicular ATP release. Channel activation is regulated by (patho)physiological stimuli, such as mechanical stimulation, making them attractive potential drug targets for the management of arterial thrombosis. This review explores the structure and function of platelet pannexin-1 and connexins, the mechanisms by which they are gated and their therapeutic potential.
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Affiliation(s)
- Kirk A Taylor
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Gemma Little
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
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41
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Tirosh A, Tuncman G, Calay ES, Rathaus M, Ron I, Tirosh A, Yalcin A, Lee YG, Livne R, Ron S, Minsky N, Arruda AP, Hotamisligil GS. Intercellular Transmission of Hepatic ER Stress in Obesity Disrupts Systemic Metabolism. Cell Metab 2021; 33:319-333.e6. [PMID: 33340456 PMCID: PMC7858244 DOI: 10.1016/j.cmet.2020.11.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 07/30/2020] [Accepted: 11/12/2020] [Indexed: 12/22/2022]
Abstract
Endoplasmic reticulum stress (ERS) has a pathophysiological role in obesity-associated insulin resistance. Yet, the coordinated tissue response to ERS remains unclear. Increased connexin 43 (Cx43)-mediated intercellular communication has been implicated in tissue-adaptive and -maladaptive response to various chronic stresses. Here, we demonstrate that in hepatocytes, ERS results in increased Cx43 expression and cell-cell coupling. Co-culture of ER-stressed "donor" cells resulted in intercellular transmission of ERS and dysfunction to ERS-naive "recipient" cells ("bystander response"), which could be prevented by genetic or pharmacologic suppression of Cx43. Hepatocytes from obese mice were able to transmit ERS to hepatocytes from lean mice, and mice lacking liver Cx43 were protected from diet-induced ERS, insulin resistance, and hepatosteatosis. Taken together, our results indicate that in obesity, the increased Cx43-mediated cell-cell coupling allows intercellular propagation of ERS. This novel maladaptive response to over-nutrition exacerbates the tissue ERS burden, promoting hepatosteatosis and impairing whole-body glucose metabolism.
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Affiliation(s)
- Amir Tirosh
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA; Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Harvard Medical School, Boston, MA 02115, USA.
| | - Gurol Tuncman
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Ediz S Calay
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Moran Rathaus
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Idit Ron
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Amit Tirosh
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Abdullah Yalcin
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Adnan Menderes Üniversitesi Medical School, Department of Medical Biology, 09100 Aydin, Turkey
| | - Yankun G Lee
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Rinat Livne
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sophie Ron
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Neri Minsky
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ana Paula Arruda
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Gökhan S Hotamisligil
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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42
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Garcia-Vega L, O’Shaughnessy EM, Albuloushi A, Martin PE. Connexins and the Epithelial Tissue Barrier: A Focus on Connexin 26. BIOLOGY 2021; 10:biology10010059. [PMID: 33466954 PMCID: PMC7829877 DOI: 10.3390/biology10010059] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 12/15/2022]
Abstract
Simple Summary Tissues that face the external environment are known as ‘epithelial tissue’ and form barriers between different body compartments. This includes the outer layer of the skin, linings of the intestine and airways that project into the lumen connecting with the external environment, and the cornea of the eye. These tissues do not have a direct blood supply and are dependent on exchange of regulatory molecules between cells to ensure co-ordination of tissue events. Proteins known as connexins form channels linking cells directly and permit exchange of small regulatory signals. A range of environmental stimuli can dysregulate the level of connexin proteins and or protein function within the epithelia, leading to pathologies including non-healing wounds. Mutations in these proteins are linked with hearing loss, skin and eye disorders of differing severity. As such, connexins emerge as prime therapeutic targets with several agents currently in clinical trials. This review outlines the role of connexins in epithelial tissue and how their dysregulation contributes to pathological pathways. Abstract Epithelial tissue responds rapidly to environmental triggers and is constantly renewed. This tissue is also highly accessible for therapeutic targeting. This review highlights the role of connexin mediated communication in avascular epithelial tissue. These proteins form communication conduits with the extracellular space (hemichannels) and between neighboring cells (gap junctions). Regulated exchange of small metabolites less than 1kDa aide the co-ordination of cellular activities and in spatial communication compartments segregating tissue networks. Dysregulation of connexin expression and function has profound impact on physiological processes in epithelial tissue including wound healing. Connexin 26, one of the smallest connexins, is expressed in diverse epithelial tissue and mutations in this protein are associated with hearing loss, skin and eye conditions of differing severity. The functional consequences of dysregulated connexin activity is discussed and the development of connexin targeted therapeutic strategies highlighted.
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Hariharan A, Weir N, Robertson C, He L, Betsholtz C, Longden TA. The Ion Channel and GPCR Toolkit of Brain Capillary Pericytes. Front Cell Neurosci 2020; 14:601324. [PMID: 33390906 PMCID: PMC7775489 DOI: 10.3389/fncel.2020.601324] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022] Open
Abstract
Brain pericytes reside on the abluminal surface of capillaries, and their processes cover ~90% of the length of the capillary bed. These cells were first described almost 150 years ago (Eberth, 1871; Rouget, 1873) and have been the subject of intense experimental scrutiny in recent years, but their physiological roles remain uncertain and little is known of the complement of signaling elements that they employ to carry out their functions. In this review, we synthesize functional data with single-cell RNAseq screens to explore the ion channel and G protein-coupled receptor (GPCR) toolkit of mesh and thin-strand pericytes of the brain, with the aim of providing a framework for deeper explorations of the molecular mechanisms that govern pericyte physiology. We argue that their complement of channels and receptors ideally positions capillary pericytes to play a central role in adapting blood flow to meet the challenge of satisfying neuronal energy requirements from deep within the capillary bed, by enabling dynamic regulation of their membrane potential to influence the electrical output of the cell. In particular, we outline how genetic and functional evidence suggest an important role for Gs-coupled GPCRs and ATP-sensitive potassium (KATP) channels in this context. We put forth a predictive model for long-range hyperpolarizing electrical signaling from pericytes to upstream arterioles, and detail the TRP and Ca2+ channels and Gq, Gi/o, and G12/13 signaling processes that counterbalance this. We underscore critical questions that need to be addressed to further advance our understanding of the signaling topology of capillary pericytes, and how this contributes to their physiological roles and their dysfunction in disease.
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Affiliation(s)
- Ashwini Hariharan
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Nick Weir
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Colin Robertson
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Liqun He
- Rudbeck Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Christer Betsholtz
- Rudbeck Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.,Department of Medicine Huddinge (MedH), Karolinska Institutet & Integrated Cardio Metabolic Centre, Huddinge, Sweden
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
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Cohen-Salmon M, Slaoui L, Mazaré N, Gilbert A, Oudart M, Alvear-Perez R, Elorza-Vidal X, Chever O, Boulay AC. Astrocytes in the regulation of cerebrovascular functions. Glia 2020; 69:817-841. [PMID: 33058289 DOI: 10.1002/glia.23924] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/18/2022]
Abstract
Astrocytes are the most numerous type of neuroglia in the brain and have a predominant influence on the cerebrovascular system; they control perivascular homeostasis, the integrity of the blood-brain barrier, the dialogue with the peripheral immune system, the transfer of metabolites from the blood, and blood vessel contractility in response to neuronal activity. These regulatory processes occur in a specialized interface composed of perivascular astrocyte extensions that almost completely cover the cerebral blood vessels. Scientists have only recently started to study how this interface is formed and how it influences cerebrovascular functions. Here, we review the literature on the astrocytes' role in the regulation of the cerebrovascular system. We cover the anatomy and development of the gliovascular interface, the known gliovascular functions, and molecular factors, the latter's implication in certain pathophysiological situations, and recent cutting-edge experimental tools developed to examine the astrocytes' role at the vascular interface. Finally, we highlight some open questions in this field of research.
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Affiliation(s)
- Martine Cohen-Salmon
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Leila Slaoui
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Noémie Mazaré
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Alice Gilbert
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Marc Oudart
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Rodrigo Alvear-Perez
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Xabier Elorza-Vidal
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Oana Chever
- Normandie University, UNIROUEN, INSERM, DC2N, IRIB, Rouen, France
| | - Anne-Cécile Boulay
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
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45
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Au A, Shao Q, White KK, Lucaciu SA, Esseltine JL, Barr K, Laird DW. Comparative Analysis of Cx31 and Cx43 in Differentiation-Competent Rodent Keratinocytes. Biomolecules 2020; 10:biom10101443. [PMID: 33066499 PMCID: PMC7602205 DOI: 10.3390/biom10101443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/30/2020] [Accepted: 10/08/2020] [Indexed: 12/25/2022] Open
Abstract
When considering connexin expression and regulation, the epidermis of the skin is one of the most complex tissues found in mammals even though it largely contains a single cell type, the keratinocyte. In the rodent epidermis, up to 9 connexin family members have been detected at the mRNA level. Many of these connexins are temporally and spatially regulated in coordination with keratinocyte progenitor cell differentiation and migration from the stratum basale to form the stratum spinosum and stratum granulosum layers before finally forming the stratum corneum. Cx43 is the principal connexin found in basal keratinocytes and to a lesser degree found in keratinocytes that have begun to differentiate where Cx26, Cx30 and Cx31 become prevalent. Here we show that the CRISPR-Cas9 ablation of Cx43 reduces overall gap junction coupling in monolayer cultures of rat epidermal keratinocytes (REKs) and dysregulates the differentiation of REKs when grown in organotypic cultures. Natively found in differentiated keratinocytes, Cx31 readily assembles into gap junctions when expressed in REKs where it can extensively co-assemble into the same gap junctions with co-expressed Cx30. Time-lapse imaging indicated that many Cx31 gap junctions are mobile within the plasma membrane undergoing both fusion and fission events. Finally, the persistence of pre-existing Cx31 gap junctions in the presence of the protein trafficking blocker, brefeldin A, is longer than that found for Cx43 gap junctions indicating that it has a distinctly different life expectancy in REKs. Collectively, this study highlights the importance of Cx43 in rodent keratinocyte differentiation and suggests that Cx31 acquires life-cycle properties that are distinct from Cx43.
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Affiliation(s)
- Akina Au
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON N6A 5C1, Canada; (A.A.); (S.A.L.)
| | - Qing Shao
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON N6A 5C1, Canada; (Q.S.); (K.K.W.); (K.B.)
| | - Kyra K. White
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON N6A 5C1, Canada; (Q.S.); (K.K.W.); (K.B.)
| | - Sergiu A. Lucaciu
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON N6A 5C1, Canada; (A.A.); (S.A.L.)
| | - Jessica L. Esseltine
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1B 3V6, Canada;
| | - Kevin Barr
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON N6A 5C1, Canada; (Q.S.); (K.K.W.); (K.B.)
| | - Dale W. Laird
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON N6A 5C1, Canada; (A.A.); (S.A.L.)
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON N6A 5C1, Canada; (Q.S.); (K.K.W.); (K.B.)
- Correspondence: ; Tel.: +1-519-661-2111 (ext. 86827)
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46
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Grubišić V, McClain JL, Fried DE, Grants I, Rajasekhar P, Csizmadia E, Ajijola OA, Watson RE, Poole DP, Robson SC, Christofi FL, Gulbransen BD. Enteric Glia Modulate Macrophage Phenotype and Visceral Sensitivity following Inflammation. Cell Rep 2020; 32:108100. [PMID: 32905782 PMCID: PMC7518300 DOI: 10.1016/j.celrep.2020.108100] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 07/02/2020] [Accepted: 08/11/2020] [Indexed: 12/20/2022] Open
Abstract
Mechanisms resulting in abdominal pain include altered neuro-immune interactions in the gastrointestinal tract, but the signaling processes that link immune activation with visceral hypersensitivity are unresolved. We hypothesized that enteric glia link the neural and immune systems of the gut and that communication between enteric glia and immune cells modulates the development of visceral hypersensitivity. To this end, we manipulated a major mechanism of glial intercellular communication that requires connexin-43 and assessed the effects on acute and chronic inflammation, visceral hypersensitivity, and immune responses. Deleting connexin-43 in glia protected against the development of visceral hypersensitivity following chronic colitis. Mechanistically, the protective effects of glial manipulation were mediated by disrupting the glial-mediated activation of macrophages through the macrophage colony-stimulating factor. Collectively, our data identified enteric glia as a critical link between gastrointestinal neural and immune systems that could be harnessed by therapies to ameliorate abdominal pain.
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Affiliation(s)
- Vladimir Grubišić
- Department of Physiology and Neuroscience Program, Michigan State University, 567 Wilson Road, East Lansing, MI 48824, USA
| | - Jonathon L McClain
- Department of Physiology and Neuroscience Program, Michigan State University, 567 Wilson Road, East Lansing, MI 48824, USA
| | - David E Fried
- Department of Physiology and Neuroscience Program, Michigan State University, 567 Wilson Road, East Lansing, MI 48824, USA
| | - Iveta Grants
- Department of Anesthesiology, The Wexner Medical Center, The Ohio State University, 420 West 12th Avenue, Room 216, Columbus, OH 43210, USA
| | - Pradeep Rajasekhar
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Melbourne, VIC, Australia
| | - Eva Csizmadia
- Division of Gastroenterology, Department of Medicine and of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Olujimi A Ajijola
- Cardiac Arrhythmia Center, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA, USA
| | - Ralph E Watson
- Department of Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Daniel P Poole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Melbourne, VIC, Australia
| | - Simon C Robson
- Division of Gastroenterology, Department of Medicine and of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Fievos L Christofi
- Department of Anesthesiology, The Wexner Medical Center, The Ohio State University, 420 West 12th Avenue, Room 216, Columbus, OH 43210, USA
| | - Brian D Gulbransen
- Department of Physiology and Neuroscience Program, Michigan State University, 567 Wilson Road, East Lansing, MI 48824, USA.
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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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48
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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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49
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Establishment and functional characterization of a murine primary Sertoli cell line deficient of connexin43. Cell Tissue Res 2020; 381:309-326. [PMID: 32328805 PMCID: PMC7369266 DOI: 10.1007/s00441-020-03203-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 03/12/2020] [Indexed: 12/12/2022]
Abstract
The Sertoli cell (SC) specific connexin43 (Cx43) knockout (SCCx43KO) mouse line is ideal to gain insight into the mechanistic gap junction formation in SC and the seminiferous epithelium. A method for developing primary SC cultures from these mice was established, validated and successfully characterized via polymerase chain reaction, immunohistochemistry, immunofluorescence (IF), and Western blots (WB). It was evident that both knockout (KO) and wild-type (WT) primary cell cultures were similar in morphology. These highly pure SC cultures were subjected to cell proliferation assays indicating no notable proliferation in cultures of both genotypes. Measurements of cell monolayer integrity indicated significant increases in transepithelial electrical resistance and consequently in tight junction expression of the KO cultures. Using semi-quantitative WB and IF, tight junction protein claudin-11 was analyzed. These results support a role for Cx43 in regulating blood-testis barrier (BTB) function, composition, and dynamics in vitro. Thus, the SC deficient Cx43 cell cultures may provide a valuable in vitro tool for a better understanding of the mechanistic role of Cx43 in spermatogenesis and BTB assembly.
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50
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Martin EA, Lasseigne AM, Miller AC. Understanding the Molecular and Cell Biological Mechanisms of Electrical Synapse Formation. Front Neuroanat 2020; 14:12. [PMID: 32372919 PMCID: PMC7179694 DOI: 10.3389/fnana.2020.00012] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/09/2020] [Indexed: 12/20/2022] Open
Abstract
In this review article, we will describe the recent advances made towards understanding the molecular and cell biological mechanisms of electrical synapse formation. New evidence indicates that electrical synapses, which are gap junctions between neurons, can have complex molecular compositions including protein asymmetries across joined cells, diverse morphological arrangements, and overlooked similarities with other junctions, all of which indicate new potential roles in neurodevelopmental disease. Aquatic organisms, and in particular the vertebrate zebrafish, have proven to be excellent models for elucidating the molecular mechanisms of electrical synapse formation. Zebrafish will serve as our main exemplar throughout this review and will be compared with other model organisms. We highlight the known cell biological processes that build neuronal gap junctions and compare these with the assemblies of adherens junctions, tight junctions, non-neuronal gap junctions, and chemical synapses to explore the unknown frontiers remaining in our understanding of the critical and ubiquitous electrical synapse.
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Affiliation(s)
- E Anne Martin
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| | - Abagael M Lasseigne
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| | - Adam C Miller
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
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