51
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Ishikawa M, Williams G, Forcinito P, Ishikawa M, Petrie RJ, Saito K, Fukumoto S, Yamada Y. Pannexin 3 ER Ca 2+ channel gating is regulated by phosphorylation at the Serine 68 residue in osteoblast differentiation. Sci Rep 2019; 9:18759. [PMID: 31822768 PMCID: PMC6904572 DOI: 10.1038/s41598-019-55371-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/19/2019] [Indexed: 12/31/2022] Open
Abstract
Pannexin 3 (Panx3) is a regulator of bone formation. Panx3 forms three distinct functional channels: hemichannels, gap junctions, and endoplasmic reticulum (ER) Ca2+ channels. However, the gating mechanisms of the Panx3 channels remain unclear. Here, we show that the Panx3 ER Ca2+ channel is modulated by phosphorylation of the serine 68 residue (Ser68) to promote osteoblast differentiation. Among the 17 candidate phosphorylation sites identified, the mutation of Ser68 to Ala (Ser68Ala) was sufficient to inhibit Panx3-mediated osteoblast differentiation via reduction of Osterix and ALP expression. Using a Ser68 phospho-specific antibody (P-Panx3) revealed Panx3 was phosphorylated in prehypertrophic, hypertrophic chondrocytes, and bone areas of the newborn growth plate. In osteogenic C2C12 cells, P-Panx3 was located on the ER membranes. Importantly, the Ser68Ala mutation only affected Panx3 ER Ca2+ channel function. Ser68 on Panx3 was phosphorylated by ATP stimulation and PI3K/Akt signaling. Finally, real-time FRET imaging and ratio analysis revealed that the Panx3 channel conformation was sensitive to ATP. Together, the phosphorylation of Panx3 at Ser68 is an essential step controlling the gating of the Panx3 ER Ca2+ channel to promote osteogenesis.
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Affiliation(s)
- Masaki Ishikawa
- Operative Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8575, Japan.
| | - Geneva Williams
- Molecular Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Philadelphia, USA
| | - Patricia Forcinito
- Molecular Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Philadelphia, USA
| | - Momoko Ishikawa
- Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8576, Japan
| | - Ryan J Petrie
- Department of Biology, Drexel University, Philadelphia, PA, 19104, USA
| | - Kan Saito
- Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8576, Japan
| | - Satoshi Fukumoto
- Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, 980-8576, Japan
| | - Yoshihiko Yamada
- Molecular Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Philadelphia, USA
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Circulating levels of ATP is a biomarker of HIV cognitive impairment. EBioMedicine 2019; 51:102503. [PMID: 31806564 PMCID: PMC7000317 DOI: 10.1016/j.ebiom.2019.10.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND In developed countries, Human Immunodeficiency Virus type-1 (HIV-1) infection has become a chronic disease despite the positive effects of anti-retroviral therapies (ART), but still at least half of the HIV infected population shown signs of cognitive impairment. Therefore, biomarkers of HIV cognitive decline are urgently needed. METHODS We analyze the opening of one of the larger channels expressed by humans, pannexin-1 (Panx-1) channels, in the uninfected and HIV infected population (n = 175). We determined channel opening and secretion of intracellular second messengers released through the channel such as PGE2 and ATP. Also, we correlated the opening of Panx-1 channels with the circulating levels of PGE2 and ATP as well as cogntive status of the individuals analyzed. FINDINGS Here, we demonstrate that Panx-1 channels on fresh PBMCs obtained from uninfected individuals are closed and no significant amounts of PGE2 and ATP are detected in the circulation. In contrast, in all HIV-infected individuals analyzed, even the ones under effective ART, a spontaneous opening of Panx-1 channels and increased circulating levels of PGE2 and ATP were detected. Circulating levels of ATP were correlated with cognitive decline in the HIV-infected population supporting that ATP is a biomarker of cognitive disease in the HIV-infected population. INTERPRETATION We propose that circulating levels of ATP could predict CNS compromise and lead to the breakthroughs necessary to detect and prevent brain compromise in the HIV-infected population.
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53
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ATP amplifies NADPH-dependent and -independent neutrophil extracellular trap formation. Sci Rep 2019; 9:16556. [PMID: 31719610 PMCID: PMC6851112 DOI: 10.1038/s41598-019-53058-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/24/2019] [Indexed: 01/21/2023] Open
Abstract
Neutrophils are the first immune cells to kill invading microbes at sites of infection using a variety of processes, including the release of proteases, phagocytosis and the production of neutrophil extracellular traps (NETs). NET formation, or NETosis, is a specific and highly efficient process, which is induced by a variety of stimuli leading to expulsion of DNA, proteases and antimicrobial peptides to the extracellular space. However, uncontrolled NETosis may lead to adverse effects and exert tissue damage in pathological conditions. Here, we show that the ATP channel pannexin1 (Panx1) is functionally expressed by bone marrow-derived neutrophils (BMDNs) of wild-type (WT) mice and that ATP contributes to NETosis induced in vitro by the calcium ionophore A23187 or phorbol 12-myristate 13-acetate (PMA). Interestingly, neutrophils isolated from Panx1−/− mice showed reduced and/or delayed induction of NETosis. Brilliant blue FCF dye (BB-FCF), a Panx1 channel inhibitor, decreased NETosis in wild-type neutrophils to the extent observed in Panx1−/− neutrophils. Thus, we demonstrate that ATP and Panx1 channels contribute to NETosis and may represent a therapeutic target.
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54
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Douanne T, André‐Grégoire G, Trillet K, Thys A, Papin A, Feyeux M, Hulin P, Chiron D, Gavard J, Bidère N. Pannexin-1 limits the production of proinflammatory cytokines during necroptosis. EMBO Rep 2019; 20:e47840. [PMID: 31410978 PMCID: PMC6776911 DOI: 10.15252/embr.201947840] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 07/22/2019] [Accepted: 07/26/2019] [Indexed: 12/31/2022] Open
Abstract
The activation of mixed lineage kinase-like (MLKL) by receptor-interacting protein kinase-3 (RIPK3) controls the execution of necroptosis, a regulated form of necrosis that occurs in apoptosis-deficient conditions. Active oligomerized MLKL triggers the exposure of phosphatidylserine residues on the cell surface and disrupts the plasma membrane integrity by forming lytic pores. MLKL also governs endosomal trafficking and biogenesis of small extracellular vesicles as well as the production of proinflammatory cytokines during the early steps of necroptosis; however, the molecular basis continues to be elucidated. Here, we find that MLKL oligomers activate Pannexin-1 (PANX1) channels, concomitantly to the loss of phosphatidylserine asymmetry. This plasma membrane "leakiness" requires the small GTPase RAB27A and RAB27B isoforms, which regulate intracellular vesicle trafficking, docking, and fusion with the plasma membrane. Although cells in which PANX1 is silenced or inhibited normally undergo necroptotic death, they display enhanced production of cytokines such as interleukin-8, indicating that PANX1 may tamper with inflammation. These data identify a novel signaling nexus between MLKL, RAB27, and PANX1 and propose ways to interfere with inflammation associated with necroptosis.
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Affiliation(s)
- Tiphaine Douanne
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
| | - Gwennan André‐Grégoire
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
- Institut de Cancérologie de l'OuestSite René GauducheauSaint‐HerblainFrance
| | - Kilian Trillet
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
| | - An Thys
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
| | - Antonin Papin
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
| | - Magalie Feyeux
- MicroPICell Imaging Core FacilitySFR Santé F. Bonamy UMS016INSERM, CNRSUniversité de NantesNantesFrance
| | - Philippe Hulin
- MicroPICell Imaging Core FacilitySFR Santé F. Bonamy UMS016INSERM, CNRSUniversité de NantesNantesFrance
| | - David Chiron
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
| | - Julie Gavard
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
- Institut de Cancérologie de l'OuestSite René GauducheauSaint‐HerblainFrance
| | - Nicolas Bidère
- CRCINA, INSERM, CNRSUniversité de NantesUniversité d'AngersNantesFrance
- GDR3697 MicronitCNRSNantesFrance
- L'Héma‐NexT, i‐Site NexTNantesFrance
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55
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Epp AL, Ebert SN, Sanchez-Arias JC, Wicki-Stordeur LE, Boyce AKJ, Swayne LA. A novel motif in the proximal C-terminus of Pannexin 1 regulates cell surface localization. Sci Rep 2019; 9:9721. [PMID: 31278290 PMCID: PMC6611761 DOI: 10.1038/s41598-019-46144-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 06/24/2019] [Indexed: 12/11/2022] Open
Abstract
The Pannexin 1 (Panx1) ion and metabolite channel is expressed in a wide variety of cells where it regulates a number of cell behaviours including proliferation and differentiation. Panx1 is expressed on the cell surface as well as intracellular membranes. Previous work suggests that a region within the proximal Panx1 C-terminus (Panx1CT) regulates cell surface localization. Here we report the discovery of a putative leucine-rich repeat (LRR) motif in the proximal Panx1CT necessary for Panx1 cell surface expression in HEK293T cells. Deletion of the putative LRR motif results in significant loss of Panx1 cell surface distribution. Outcomes of complementary cell surface oligomerization and glycosylation state analyses were consistent with reduced cell surface expression of Panx1 LRR deletion mutants. Of note, the oligomerization analysis revealed the presence of putative dimers and trimers of Panx1 at the cell surface. Expression of Panx1 increased HEK293T cell growth and reduced doubling time, while expression of a Panx1 LRR deletion mutant (highly conserved segment) did not reproduce this effect. In summary, here we discovered the presence of a putative LRR motif in the Panx1CT that impacts on Panx1 cell surface localization. Overall these findings provide new insights into the molecular mechanisms underlying C-terminal regulation of Panx1 trafficking and raise potential new lines of investigation with respect to Panx1 oligomerization and glycosylation.
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Affiliation(s)
- Anna L Epp
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, V8P 5C2, Canada
| | - Sarah N Ebert
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, V8P 5C2, Canada
| | - Juan C Sanchez-Arias
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, V8P 5C2, Canada
| | - Leigh E Wicki-Stordeur
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, V8P 5C2, Canada
| | - Andrew K J Boyce
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, V8P 5C2, Canada
| | - Leigh Anne Swayne
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, V8P 5C2, Canada.
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56
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Ahmadian E, Eftekhari A, Samiei M, Maleki Dizaj S, Vinken M. The role and therapeutic potential of connexins, pannexins and their channels in Parkinson's disease. Cell Signal 2019; 58:111-118. [DOI: 10.1016/j.cellsig.2019.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/10/2019] [Accepted: 03/10/2019] [Indexed: 02/07/2023]
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57
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Destination and consequences of Panx1 and mutant expression in polarized MDCK cells. Exp Cell Res 2019; 381:235-247. [PMID: 31102595 DOI: 10.1016/j.yexcr.2019.05.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/09/2019] [Accepted: 05/11/2019] [Indexed: 12/12/2022]
Abstract
The channel-forming membrane glycoprotein pannexin 1 (Panx1) is best characterized as an ATP release channel. To investigate the trafficking and sorting of Panx1, we used polarized MDCK cells and non-polarized BICR-M1Rk cells to track the fate of GFP-tagged Panx1. In non-polarized cells, Panx1 was found throughout the plasma membrane, including the lamellipodia of the tumor cells and the cell surface-targeting domain was mapped to residues 307-379. Panx1 was preferentially enriched at the apical membrane domain of polarized MDCK cells grown as monolayer sheets or as spheroids. Residual Panx1 localized within basolateral membranes of polarized MDCK cells was independent of a putative dileucine sorting motif LL365/6 found within the C-terminal of Panx1. Unexpectedly, stable expression of a Panx1 mutant, where a putative tyrosine-based basolateral sorting motif (YxxØ) was mutated (Y308F), or a truncated Δ379 Panx1 mutant, caused MDCK cells to lose cell-cell contacts and their ability to polarize as they underwent a switch to a more fibroblast-like phenotype. We conclude that Panx1 is preferentially delivered to the apical domain of polarized epithelial cells, and Panx1 mutants drive phenotypic changes to MDCK cells preventing their polarization.
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58
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Dispelling myths about connexins, pannexins and P2X7 in hypoxic-ischemic central nervous system. Neurosci Lett 2019; 695:76-85. [PMID: 29195910 DOI: 10.1016/j.neulet.2017.11.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 10/07/2017] [Accepted: 11/21/2017] [Indexed: 01/17/2023]
Abstract
In membrane physiology, as in other fields, myths or speculations may be repeated so often and so widely that they are perceived as facts. To some extent, this has occurred with regard to gap junctions, hemichannels, pannexin channels and P2X7 (ionotropic receptors), especially concerning the interpretation of the individual role of these channels in hypoxic-ischemic CNS since these channels may be closed by the same pharmacological blockers. Significance of existing controversial data are highlighted and contradictory views from different groups are critically discussed herein.
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59
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Pannexin 2 Localizes at ER-Mitochondria Contact Sites. Cancers (Basel) 2019; 11:cancers11030343. [PMID: 30862038 PMCID: PMC6468579 DOI: 10.3390/cancers11030343] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/22/2019] [Accepted: 02/27/2019] [Indexed: 01/02/2023] Open
Abstract
Endomembrane specialization allows functional compartmentalization but imposes physical constraints to information flow within the cell. However, the evolution of an endomembrane system was associated with the emergence of contact sites facilitating communication between membrane-bound organelles. Contact sites between the endoplasmic reticulum (ER) and mitochondria are highly conserved in terms of their morphological features but show surprising molecular diversity within and across eukaryote species. ER-mitochondria contact sites are thought to regulate key processes in oncogenesis but their molecular composition remains poorly characterized in mammalian cells. In this study, we investigate the localization of pannexin 2 (Panx2), a membrane channel protein showing tumor-suppressing properties in cancer cells. Using a combination of subcellular fractionation, particle tracking in live-cell, and immunogold electron microscopy, we show that Panx2 localizes at ER-mitochondria contact sites in mammalian cells and sensitizes cells to apoptotic stimuli.
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60
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Beckmann A, Hainz N, Tschernig T, Meier C. Facets of Communication: Gap Junction Ultrastructure and Function in Cancer Stem Cells and Tumor Cells. Cancers (Basel) 2019; 11:cancers11030288. [PMID: 30823688 PMCID: PMC6468480 DOI: 10.3390/cancers11030288] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 02/22/2019] [Accepted: 02/25/2019] [Indexed: 12/28/2022] Open
Abstract
Gap junction proteins are expressed in cancer stem cells and non-stem cancer cells of many tumors. As the morphology and assembly of gap junction channels are crucial for their function in intercellular communication, one focus of our review is to outline the data on gap junction plaque morphology available for cancer cells. Electron microscopic studies and freeze-fracture analyses on gap junction ultrastructure in cancer are summarized. As the presence of gap junctions is relevant in solid tumors, we exemplarily outline their role in glioblastomas and in breast cancer. These were also shown to contain cancer stem cells, which are an essential cause of tumor onset and of tumor transmission into metastases. For these processes, gap junctional communication was shown to be important and thus we summarize, how the expression of gap junction proteins and the resulting communication between cancer stem cells and their surrounding cells contributes to the dissemination of cancer stem cells via blood or lymphatic vessels. Based on their importance for tumors and metastases, future cancer-specific therapies are expected to address gap junction proteins. In turn, gap junctions also seem to contribute to the unattainability of cancer stem cells by certain treatments and might thus contribute to therapeutic resistance.
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Affiliation(s)
- Anja Beckmann
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany.
| | - Nadine Hainz
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany.
| | - Thomas Tschernig
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany.
| | - Carola Meier
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany.
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61
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DeLalio LJ, Billaud M, Ruddiman CA, Johnstone SR, Butcher JT, Wolpe AG, Jin X, Keller TCS, Keller AS, Rivière T, Good ME, Best AK, Lohman AW, Swayne LA, Penuela S, Thompson RJ, Lampe PD, Yeager M, Isakson BE. Constitutive SRC-mediated phosphorylation of pannexin 1 at tyrosine 198 occurs at the plasma membrane. J Biol Chem 2019; 294:6940-6956. [PMID: 30814251 DOI: 10.1074/jbc.ra118.006982] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/15/2019] [Indexed: 11/06/2022] Open
Abstract
Pannexin 1 (PANX1)-mediated ATP release in vascular smooth muscle coordinates α1-adrenergic receptor (α1-AR) vasoconstriction and blood pressure homeostasis. We recently identified amino acids 198-200 (YLK) on the PANX1 intracellular loop that are critical for α1-AR-mediated vasoconstriction and PANX1 channel function. We report herein that the YLK motif is contained within an SRC homology 2 domain and is directly phosphorylated by SRC proto-oncogene, nonreceptor tyrosine kinase (SRC) at Tyr198 We demonstrate that PANX1-mediated ATP release occurs independently of intracellular calcium but is sensitive to SRC family kinase (SFK) inhibition, suggestive of channel regulation by tyrosine phosphorylation. Using a PANX1 Tyr198-specific antibody, SFK inhibitors, SRC knockdown, temperature-dependent SRC cells, and kinase assays, we found that PANX1-mediated ATP release and vasoconstriction involves constitutive phosphorylation of PANX1 Tyr198 by SRC. We specifically detected SRC-mediated Tyr198 phosphorylation at the plasma membrane and observed that it is not enhanced or induced by α1-AR activation. Last, we show that PANX1 immunostaining is enriched in the smooth muscle layer of arteries from hypertensive humans and that Tyr198 phosphorylation is detectable in these samples, indicative of a role for membrane-associated PANX1 in small arteries of hypertensive humans. Our discovery adds insight into the regulation of PANX1 by post-translational modifications and connects a significant purinergic vasoconstriction pathway with a previously identified, yet unexplored, tyrosine kinase-based α1-AR constriction mechanism. This work implicates SRC-mediated PANX1 function in normal vascular hemodynamics and suggests that Tyr198-phosphorylated PANX1 is involved in hypertensive vascular pathology.
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Affiliation(s)
- Leon J DeLalio
- From the Robert M. Berne Cardiovascular Research Center.,Department of Pharmacology
| | - Marie Billaud
- the Department of Cardiothoracic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Claire A Ruddiman
- From the Robert M. Berne Cardiovascular Research Center.,Department of Pharmacology
| | | | - Joshua T Butcher
- the Department of Physiology, Augusta University, Augusta, Georgia 30912
| | - Abigail G Wolpe
- From the Robert M. Berne Cardiovascular Research Center.,Department of Cell Biology, and
| | - Xueyao Jin
- Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - T C Stevenson Keller
- From the Robert M. Berne Cardiovascular Research Center.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - Alexander S Keller
- From the Robert M. Berne Cardiovascular Research Center.,Department of Pharmacology
| | - Thibaud Rivière
- the Department of Life and Health Sciences, University of Bordeaux, 33000 Bordeaux, France
| | | | - Angela K Best
- From the Robert M. Berne Cardiovascular Research Center
| | - Alexander W Lohman
- the Hotchkiss Brain Institute and.,Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Leigh Anne Swayne
- the Division of Medical Sciences, Centre for Biomedical Research, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Silvia Penuela
- the Departments of Anatomy and Cell Biology and Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 3K7, Canada, and
| | - Roger J Thompson
- the Hotchkiss Brain Institute and.,Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Paul D Lampe
- the Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
| | - Mark Yeager
- Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - Brant E Isakson
- From the Robert M. Berne Cardiovascular Research Center, .,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia 22908
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62
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Zhou KQ, Green CR, Bennet L, Gunn AJ, Davidson JO. The Role of Connexin and Pannexin Channels in Perinatal Brain Injury and Inflammation. Front Physiol 2019; 10:141. [PMID: 30873043 PMCID: PMC6400979 DOI: 10.3389/fphys.2019.00141] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/07/2019] [Indexed: 12/21/2022] Open
Abstract
Perinatal brain injury remains a major cause of death and life-long disability. Perinatal brain injury is typically associated with hypoxia-ischemia and/or infection/inflammation. Both hypoxia-ischemia and infection trigger an inflammatory response in the brain. The inflammatory response can contribute to brain cell loss and chronic neuroinflammation leading to neurological impairments. It is now well-established that brain injury evolves over time, and shows a striking spread from injured to previously uninjured regions of the brain. There is increasing evidence that this spread is related to opening of connexin hemichannels and pannexin channels, both of which are large conductance membrane channels found in almost all cell types in the brain. Blocking connexin hemichannels within the first 3 h after hypoxia-ischemia has been shown to improve outcomes in term equivalent fetal sheep but it is important to also understand the downstream pathways linking membrane channel opening with the development of injury in order to identify new therapeutic targets. Open membrane channels release adenosine triphosphate (ATP), and other neuroactive molecules, into the extracellular space. ATP has an important physiological role, but has also been reported to act as a damage-associated molecular pattern (DAMP) signal mediated through specific purinergic receptors and so act as a primary signal 1 in the innate immune system inflammasome pathway. More crucially, extracellular ATP is a key inflammasome signal 2 activator, with purinergic receptor binding triggering the assembly of the multi-protein inflammasome complex. The inflammasome pathway and complex formation contribute to activation of inflammatory caspases, and the release of inflammatory cytokines, including interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-18, and vascular endothelial growth factor (VEGF). We propose that the NOD-like receptor protein-3 (NLRP3) inflammasome, which has been linked to inflammatory responses in models of ischemic stroke and various inflammatory diseases, may be one mechanism by which connexin hemichannel opening especially mediates perinatal brain injury.
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Affiliation(s)
- Kelly Q Zhou
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand.,Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
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63
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König B, Stauber T. Biophysics and Structure-Function Relationships of LRRC8-Formed Volume-Regulated Anion Channels. Biophys J 2019; 116:1185-1193. [PMID: 30871717 PMCID: PMC6451053 DOI: 10.1016/j.bpj.2019.02.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/31/2019] [Accepted: 02/19/2019] [Indexed: 01/25/2023] Open
Abstract
Volume-regulated anion channels (VRACs) are key players in regulatory volume decrease of vertebrate cells by mediating the extrusion of chloride and organic osmolytes. They play additional roles in various physiological processes beyond their role in osmotic volume regulation. VRACs are formed by heteromers of LRRC8 proteins; LRRC8A (also called SWELL1) is an essential subunit that combines with any of its paralogs, LRRC8B–E, to form hexameric VRAC complexes. The subunit composition of VRACs determines electrophysiological characteristics of their anion transport such as single-channel conductance, outward rectification, and depolarization-dependent inactivation kinetics. In addition, differently composed VRACs conduct diverse substrates, such as LRRC8D enhancing VRAC permeability to organic substances like taurine or cisplatin. Here, after a recapitulation of the biophysical properties of VRAC-mediated ion and osmolyte transport, we summarize the insights gathered since the molecular identification of VRACs. We describe the recently solved structures of LRRC8 complexes and discuss them in terms of their structure-function relationships. These studies open up many potential avenues for future research.
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Affiliation(s)
- Benjamin König
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Berlin, Germany
| | - Tobias Stauber
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Berlin, Germany.
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Chen W, Zhu S, Wang Y, Li J, Qiang X, Zhao X, Yang H, D'Angelo J, Becker L, Wang P, Tracey KJ, Wang H. Enhanced Macrophage Pannexin 1 Expression and Hemichannel Activation Exacerbates Lethal Experimental Sepsis. Sci Rep 2019; 9:160. [PMID: 30655582 PMCID: PMC6336828 DOI: 10.1038/s41598-018-37232-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 12/04/2018] [Indexed: 12/20/2022] Open
Abstract
We have recently reported an important role of Connexin 43 (Cx43) hemichannels in the pathogenesis of lethal sepsis through facilitating ATP efflux to potentiate the double-stranded RNA-activated protein kinase R (PKR)-dependent macrophage activation. Here we further elucidated the possible role of Pannexin 1 (Panx1) hemichannel in lethal sepsis by assessing its expression along with the impact of a Panx1-specific mimetic inhibitory peptide, 10Panx, on macrophage hemichannel activity in vitro and animal sepsis lethality in vivo. Both crude bacterial lipopolysaccharide (LPS) and purified serum amyloid A (SAA) effectively induced the expression and extracellular release of Panx1 by macrophages or monocytes as judged by Western blotting and immunocytochemistry assays. In animal model of lethal sepsis, Panx1 expression levels were significantly elevated in the heart, but reduced in the kidney, lung, spleen, and blood. At relatively lower doses (10, 50, and 100 mg/kg), the Panx1 mimetic peptide, 10Panx, reproducibly exacerbated the sepsis-induced animal lethality, reducing survival rates from 60-70% to 0-10%. Consistently, 10Panx did not inhibit, but rather promoted, the LPS-induced elevation of Lucifer Yellow dye uptake, ATP release, and Nitric Oxide (NO) production. Collectively, these findings suggested that elevated macrophage Panx1 expression and hemichannel activation contribute to the pathogenesis of lethal sepsis.
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Affiliation(s)
- Weiqiang Chen
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
| | - Shu Zhu
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
| | - Yongjun Wang
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
| | - Jianhua Li
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
| | - Xiaoling Qiang
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA
| | - Xiaoling Zhao
- Department of Pathology, New York University School of Medicine, 550 1st Ave, New York, NY, 10016, USA
| | - Huan Yang
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
| | - John D'Angelo
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA
| | - Lance Becker
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA
| | - Ping Wang
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA
| | - Kevin J Tracey
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA
| | - Haichao Wang
- The Feinstein Institute for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY, 11030, USA.
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA.
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65
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Inhibition of Pannexin 1 Reduces the Tumorigenic Properties of Human Melanoma Cells. Cancers (Basel) 2019; 11:cancers11010102. [PMID: 30654593 PMCID: PMC6356688 DOI: 10.3390/cancers11010102] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/09/2019] [Accepted: 01/10/2019] [Indexed: 01/19/2023] Open
Abstract
Pannexin 1 (PANX1) is a channel-forming glycoprotein expressed in many tissues including the skin. PANX1 channels allow the passage of ions and molecules up to 1 kDa, including ATP and other metabolites. In this study, we show that PANX1 is highly expressed in human melanoma tumors at all stages of disease progression, as well as in patient-derived cells and established melanoma cell lines. Reducing PANX1 protein levels using shRNA or inhibiting channel function with the channel blockers, carbenoxolone (CBX) and probenecid (PBN), significantly decreased cell growth and migration, and increased melanin production in A375-P and A375-MA2 cell lines. Further, treatment of A375-MA2 tumors in chicken embryo xenografts with CBX or PBN significantly reduced melanoma tumor weight and invasiveness. Blocking PANX1 channels with PBN reduced ATP release in A375-P cells, suggesting a potential role for PANX1 in purinergic signaling of melanoma cells. In addition, cell-surface biotinylation assays indicate that there is an intracellular pool of PANX1 in melanoma cells. PANX1 likely modulates signaling through the Wnt/β-catenin pathway, because β-catenin levels were significantly decreased upon PANX1 silencing. Collectively, our findings identify a role for PANX1 in controlling growth and tumorigenic properties of melanoma cells contributing to signaling pathways that modulate melanoma progression.
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66
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Pannexin 1 inhibits rhabdomyosarcoma progression through a mechanism independent of its canonical channel function. Oncogenesis 2018; 7:89. [PMID: 30459312 PMCID: PMC6246549 DOI: 10.1038/s41389-018-0100-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 11/05/2018] [Indexed: 01/22/2023] Open
Abstract
Rhabdomyosarcoma (RMS) is an aggressive soft tissue sarcoma of childhood thought to arise from impaired differentiation of skeletal muscle progenitors. We have recently identified Pannexin 1 (PANX1) channels as a novel regulator of skeletal myogenesis. In the present study, we determined that PANX1 transcript and protein levels are down-regulated in embryonal (eRMS) and alveolar RMS (aRMS) patient-derived cell lines and primary tumor specimens as compared to differentiated skeletal muscle myoblasts and tissue, respectively. While not sufficient to overcome the inability of RMS to reach terminal differentiation, ectopic expression of PANX1 in eRMS (Rh18) and aRMS (Rh30) cells significantly decreased their proliferative and migratory potential. Furthermore, ectopic PANX1 abolished 3D spheroid formation in eRMS and aRMS cells and induced regression of established spheroids through induction of apoptosis. Notably, PANX1 expression also significantly reduced the growth of human eRMS and aRMS tumor xenografts in vivo. Interestingly, PANX1 does not form active channels when expressed in eRMS (Rh18) and aRMS (Rh30) cells and the addition of PANX1 channel inhibitors did not alter or reverse the PANX1-mediated reduction of cell proliferation and migration. Moreover, expression of channel-defective PANX1 mutants not only disrupted eRMS and aRMS 3D spheroids, but also inhibited in vivo RMS tumor growth. Altogether our findings suggest that PANX1 alleviates RMS malignant properties in vitro and in vivo through a process that is independent of its canonical channel function.
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67
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Lee VR, Barr KJ, Kelly JJ, Johnston D, Brown CFC, Robb KP, Sayedyahossein S, Huang K, Gros R, Flynn LE, Penuela S. Pannexin 1 regulates adipose stromal cell differentiation and fat accumulation. Sci Rep 2018; 8:16166. [PMID: 30385873 PMCID: PMC6212408 DOI: 10.1038/s41598-018-34234-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 10/11/2018] [Indexed: 12/20/2022] Open
Abstract
Pannexin 1 (Panx1) is a channel-forming glycoprotein important in paracrine signaling and cellular development. In this study, we discovered that mice globally lacking Panx1 (KO) have significantly greater total fat mass and reduced lean mass compared to wild type (WT) mice under a normal diet. Despite having higher fat content, Panx1 KO mice on a high fat diet exhibited no differences in weight gain and blood markers of obesity as compared to WT controls, except for an increase in glucose and insulin levels. However, metabolic cage data revealed that these Panx1 KO mice display significantly increased activity levels, higher ambulatory activity, and reduced sleep duration relative to their WT littermates on a high-fat diet. To uncover the cellular mechanism responsible for the increased fat content in the KO, we isolated primary cultures of adipose-derived stromal cells (ASCs) from WT and KO fat pads. In WT ASCs we observed that Panx1 protein levels increase upon induction into an adipogenic lineage. ASCs isolated from Panx1 KO mice proliferate less but demonstrate enhanced adipogenic differentiation with increased intracellular lipid accumulation, glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, and adipokine secretion, as compared to WT ASCs. This was consistent with the increased adipocyte size and decreased adipocyte numbers observed in subcutaneous fat of the Panx1 KO mice compared to WT. We concluded that Panx1 plays a key role in adipose stromal cells during the early stages of adipogenic proliferation and differentiation, regulating fat accumulation in vivo.
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Affiliation(s)
- Vanessa R Lee
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Kevin J Barr
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - John J Kelly
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Danielle Johnston
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Cody F C Brown
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Kevin P Robb
- Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario, Canada
| | - Samar Sayedyahossein
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Kenneth Huang
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Robert Gros
- Departments of Physiology and Pharmacology, and of Medicine, University of Western Ontario, London, Ontario, Canada
- Molecular Medicine Research Group Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Lauren E Flynn
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada
- Department of Chemical and Biochemical Engineering, University of Western Ontario, London, Ontario, Canada
| | - Silvia Penuela
- Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A5C1, Canada.
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Abstract
The connexin family of channel-forming proteins is present in every tissue type in the human anatomy. Connexins are best known for forming clustered intercellular channels, structurally known as gap junctions, where they serve to exchange members of the metabolome between adjacent cells. In their single-membrane hemichannel form, connexins can act as conduits for the passage of small molecules in autocrine and paracrine signalling. Here, we review the roles of connexins in health and disease, focusing on the potential of connexins as therapeutic targets in acquired and inherited diseases as well as wound repair, while highlighting the associated clinical challenges.
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69
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Sanchez-Pupo RE, Johnston D, Penuela S. N-Glycosylation Regulates Pannexin 2 Localization but Is Not Required for Interacting with Pannexin 1. Int J Mol Sci 2018; 19:ijms19071837. [PMID: 29932112 PMCID: PMC6073767 DOI: 10.3390/ijms19071837] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/16/2018] [Accepted: 06/20/2018] [Indexed: 02/07/2023] Open
Abstract
Pannexins (Panx1, 2, 3) are channel-forming glycoproteins expressed in mammalian tissues. We previously reported that N-glycosylation acts as a regulator of the localization and intermixing of Panx1 and Panx3, but its effects on Panx2 are currently unknown. Panx1 and Panx2 intermixing can regulate channel properties, and both pannexins have been implicated in neuronal cell death after ischemia. Our objectives were to validate the predicted N-glycosylation site of Panx2 and to study the effects of Panx2 glycosylation on localization and its capacity to interact with Panx1. We used site-directed mutagenesis, enzymatic de-glycosylation, cell-surface biotinylation, co-immunoprecipitation, and confocal microscopy. Our results showed that N86 is the only N-glycosylation site of Panx2. Panx2 and the N86Q mutant are predominantly localized to the endoplasmic reticulum (ER) and cis-Golgi matrix with limited cell surface localization was seen only in the presence of Panx1. The Panx2 N86Q mutant is glycosylation-deficient and tends to aggregate in the ER reducing its cell surface trafficking but it can still interact with Panx1. Our study indicates that N-glycosylation may be important for folding and trafficking of Panx2. We found that the un-glycosylated forms of Panx1 and 2 can readily interact, regulating their localization and potentially their channel function in cells where they are co-expressed.
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Affiliation(s)
- Rafael E Sanchez-Pupo
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A5C1, Canada.
| | - Danielle Johnston
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A5C1, Canada.
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A5C1, Canada.
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70
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Zhou P, Polovitskaya MM, Jentsch TJ. LRRC8 N termini influence pore properties and gating of volume-regulated anion channels (VRACs). J Biol Chem 2018; 293:13440-13451. [PMID: 29925591 PMCID: PMC6120214 DOI: 10.1074/jbc.ra118.002853] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/19/2018] [Indexed: 12/22/2022] Open
Abstract
Volume-regulated anion channels (VRACs) are crucial for cell volume regulation and have various roles in physiology and pathology. VRACs were recently discovered to be formed by heteromers of leucine-rich repeat–containing 8 (LRRC8) proteins. However, the structural determinants of VRAC permeation and gating remain largely unknown. We show here that the short stretch preceding the first LRRC8 transmembrane domain determines VRAC conductance, ion permeability, and inactivation gating. Substituted-cysteine accessibility studies revealed that several of the first 15 LRRC8 residues are functionally important and exposed to a hydrophilic environment. Substituting glutamate 6 with cysteine decreased the amplitudes of swelling-activated ICl,vol currents, strongly increased iodide-over-chloride permeability, and markedly shifted the voltage dependence of channel inactivation. Importantly, these effects were reversed by 2-sulfonatoethyl methanethiosulfonate, which restores the negative charge at this amino acid position. Cd2+-mediated blocking of ICl,vol in cysteine variants suggested that the LRRC8 N termini come close together in the multimeric channel complex and might form part of the pore. We propose a model in which the N termini of the LRRC8 subunits line the cytoplasmic portion of the VRAC pore, possibly by folding back into the ion permeation pathway.
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Affiliation(s)
- Pingzheng Zhou
- From the Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
| | - Maya M Polovitskaya
- From the Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Graduate Program, Faculty of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Thomas J Jentsch
- From the Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany, .,Neurocure Cluster of Excellence, Charité Universitätsmedizin, D-10117 Berlin, Germany, and
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71
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Dahl G. The Pannexin1 membrane channel: distinct conformations and functions. FEBS Lett 2018; 592:3201-3209. [PMID: 29802622 DOI: 10.1002/1873-3468.13115] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 05/21/2018] [Indexed: 12/15/2022]
Abstract
The Pannexin1 (Panx1) membrane channel responds to different stimuli with distinct channel conformations. Most stimuli induce a large cation- and ATP-permeable conformation, hence Panx1 is involved in many physiological processes entailing purinergic signaling. For example, oxygen delivery in the peripheral circulatory system is regulated by ATP released from red blood cells and endothelial cells through Panx1 channels. The same membrane channel, however, when stimulated by positive membrane potential or by cleavage with caspase 3, is highly selective for the passage of chloride ions, excluding cations and ATP. Although biophysical data do not allow a distinction between the chloride-selective channels induced by voltage or by caspase cleavage, there must be other subtle differences in the structure, because overexpression of wtPanx1 is well tolerated by cells, while expression of the truncation mutant Panx1Δ378 results in slow cell death. Thus, in addition to the well-characterized two open conformations, there might be a third, more subtle conformational change involved in cell death.
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Affiliation(s)
- Gerhard Dahl
- Department of Physiology and Biophysics, University of Miami School of Medicine, FL, USA
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72
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Molica F, Figueroa XF, Kwak BR, Isakson BE, Gibbins JM. Connexins and Pannexins in Vascular Function and Disease. Int J Mol Sci 2018; 19:ijms19061663. [PMID: 29874791 PMCID: PMC6032213 DOI: 10.3390/ijms19061663] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 12/24/2022] Open
Abstract
Connexins (Cxs) and pannexins (Panxs) are ubiquitous membrane channel forming proteins that are critically involved in many aspects of vascular physiology and pathology. The permeation of ions and small metabolites through Panx channels, Cx hemichannels and gap junction channels confers a crucial role to these proteins in intercellular communication and in maintaining tissue homeostasis. This review provides an overview of current knowledge with respect to the pathophysiological role of these channels in large arteries, the microcirculation, veins, the lymphatic system and platelet function. The essential nature of these membrane proteins in vascular homeostasis is further emphasized by the pathologies that are linked to mutations and polymorphisms in Cx and Panx genes.
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Affiliation(s)
- Filippo Molica
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland.
| | - Xavier F Figueroa
- Departamento de Fisiología, Faculdad de Ciencias Biológicas, Pontifica Universidad Católica de Chile, Santiago 8330025, Chile.
| | - Brenda R Kwak
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland.
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
- Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
| | - Jonathan M Gibbins
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading RG6 6AS, UK.
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73
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Boucher J, Simonneau C, Denet G, Clarhaut J, Balandre AC, Mesnil M, Cronier L, Monvoisin A. Pannexin-1 in Human Lymphatic Endothelial Cells Regulates Lymphangiogenesis. Int J Mol Sci 2018; 19:ijms19061558. [PMID: 29882918 PMCID: PMC6032340 DOI: 10.3390/ijms19061558] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/17/2018] [Accepted: 05/22/2018] [Indexed: 12/23/2022] Open
Abstract
The molecular mechanisms governing the formation of lymphatic vasculature are not yet well understood. Pannexins are transmembrane proteins that form channels which allow for diffusion of ions and small molecules (<1 kDa) between the extracellular space and the cytosol. The expression and function of pannexins in blood vessels have been studied in the last few decades. Meanwhile, no studies have been conducted to evaluate the role of pannexins during human lymphatic vessel formation. Here we show, using primary human dermal lymphatic endothelial cells (HDLECs), pharmacological tools (probenecid, Brilliant Blue FCF, mimetic peptides [10Panx]) and siRNA-mediated knockdown that Pannexin-1 is necessary for capillary tube formation on Matrigel and for VEGF-C-induced invasion. These results newly identify Pannexin-1 as a protein highly expressed in HDLECs and its requirement during in vitro lymphangiogenesis.
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Affiliation(s)
- Jonathan Boucher
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
| | - Claire Simonneau
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
| | - Golthlay Denet
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
| | - Jonathan Clarhaut
- CNRS UMR 7285, Institut de Chimie des Milieux et des Matériaux de Poitiers (IC2MP), University of Poitiers, 86073 Poitiers, France.
- CHU de Poitiers, 86021 Poitiers, France.
| | - Annie-Claire Balandre
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
| | - Marc Mesnil
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
| | - Laurent Cronier
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
| | - Arnaud Monvoisin
- CNRS ERL 7003, Laboratoire "Signalisation & Transports Ioniques Membranaires", University of Poitiers, 86073 Poitiers, France.
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74
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Pham TL, St-Pierre ME, Ravel-Chapuis A, Parks TEC, Langlois S, Penuela S, Jasmin BJ, Cowan KN. Expression of Pannexin 1 and Pannexin 3 during skeletal muscle development, regeneration, and Duchenne muscular dystrophy. J Cell Physiol 2018; 233:7057-7070. [PMID: 29744875 DOI: 10.1002/jcp.26629] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 03/30/2018] [Indexed: 01/17/2023]
Abstract
Pannexin 1 (Panx1) and Pannexin 3 (Panx3) are single membrane channels recently implicated in myogenic commitment, as well as myoblast proliferation and differentiation in vitro. However, their expression patterns during skeletal muscle development and regeneration had yet to be investigated. Here, we show that Panx1 levels increase during skeletal muscle development becoming highly expressed together with Panx3 in adult skeletal muscle. In adult mice, Panx1 and Panx3 were differentially expressed in fast- and slow-twitch muscles. We also report that Panx1/PANX1 and Panx3/PANX3 are co-expressed in mouse and human satellite cells, which play crucial roles in skeletal muscle regeneration. Interestingly, Panx1 and Panx3 levels were modulated in muscle degeneration/regeneration, similar to the pattern seen during skeletal muscle development. As Duchenne muscular dystrophy is characterized by skeletal muscle degeneration and impaired regeneration, we next used mild and severe mouse models of this disease and found a significant dysregulation of Panx1 and Panx3 levels in dystrophic skeletal muscles. Together, our results are the first demonstration that Panx1 and Panx3 are differentially expressed amongst skeletal muscle types with their levels being highly modulated during skeletal muscle development, regeneration, and dystrophy. These findings suggest that Panx1 and Panx3 channels may play important and distinct roles in healthy and diseased skeletal muscles.
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Affiliation(s)
- Tammy L Pham
- Molecular Biomedicine Program, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Marie-Eve St-Pierre
- Molecular Biomedicine Program, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Aymeric Ravel-Chapuis
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Tara E C Parks
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Stéphanie Langlois
- Molecular Biomedicine Program, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.,Department of Surgery, Division of Pediatric Surgery, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Bernard J Jasmin
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Kyle N Cowan
- Molecular Biomedicine Program, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.,Department of Surgery, Division of Pediatric Surgery, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
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75
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Wang J, Jackson DG, Dahl G. Cationic control of Panx1 channel function. Am J Physiol Cell Physiol 2018; 315:C279-C289. [PMID: 29719168 DOI: 10.1152/ajpcell.00303.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The sequence and predicted membrane topology of pannexin1 (Panx1) places it in the family of gap junction proteins. However, rather than forming gap junction channels, Panx1 forms channels in the nonjunctional membrane. Panx1 operates in two distinct open states, depending on the mode of stimulation. The exclusively voltage-gated channel has a small conductance (<100 pS) and is highly selective for the flux of chloride ions. The Panx1 channel activated by various physiological stimuli or by increased concentrations of extracellular potassium ions has a large conductance (~500 pS, however, with multiple, long-lasting subconductance states) and is nonselectively permeable to small molecules, including ATP. To test whether the two open conformations also differ pharmacologically, the effects of di-and trivalent cations on the two Panx1 channel conformations were investigated. The rationale for this venture was that, under certain experimental conditions, ATP release from cells can be inhibited by multivalent cations, yet the literature indicates that the ATP release channel Panx1 is not affected by these ions. Consistent with previous reports, the Panx1 channel was not activated by removal of extracellular Ca2+ and the currents through the voltage-activated channel were not altered by Ca2+, Zn2+, Ba2+, or Gd3+. In contrast, the Panx1 channel activated to the large channel conformation by extracellular K+, osmotic stress, or low oxygen was inhibited by the multivalent cations in a dose-dependent way. Thus, monovalent cations activated the Panx1 channel from the closed state to the "large" conformation, while di- and trivalent cations exclusively inhibited this large channel conformation.
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Affiliation(s)
- Junjie Wang
- Department of Physiology and Biophysics, University of Miami School of Medicine , Miami, Florida
| | - David George Jackson
- Department of Physiology and Biophysics, University of Miami School of Medicine , Miami, Florida
| | - Gerhard Dahl
- Department of Physiology and Biophysics, University of Miami School of Medicine , Miami, Florida
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76
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Whyte-Fagundes P, Kurtenbach S, Zoidl C, Shestopalov VI, Carlen PL, Zoidl G. A Potential Compensatory Role of Panx3 in the VNO of a Panx1 Knock Out Mouse Model. Front Mol Neurosci 2018; 11:135. [PMID: 29780304 PMCID: PMC5946002 DOI: 10.3389/fnmol.2018.00135] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 04/03/2018] [Indexed: 12/30/2022] Open
Abstract
Pannexins (Panx) are integral membrane proteins, with Panx1 being the best-characterized member of the protein family. Panx1 is implicated in sensory processing, and knockout (KO) animal models have become the primary tool to investigate the role(s) of Panx1 in sensory systems. Extending previous work from our group on primary olfaction, the expression patterns of Panxs in the vomeronasal organ (VNO), an auxiliary olfactory sense organ with a role in reproduction and social behavior, were compared. Using qRT-PCR and Immunohistochemistry (IHC), we confirmed the loss of Panx1, found similar Panx2 expression levels in both models, and a significant upregulation of Panx3 in mice with a global ablation of Panx1. Specifically, Panx3 showed upregulated expression in nerve fibers of the non-sensory epithelial layer in juvenile and adult KO mice and in the sensory layer of adults, which overlaps with Panx1 expression areas in WT populations. Since both social behavior and evoked ATP release in the VNO was not compromised in KO animals, we hypothesized that Panx3 could compensate for the loss of Panx1. This led us to compare Panx1 and Panx3 channels in vitro, demonstrating similar dye uptake and ATP release properties. Outcomes of this study strongly suggest that Panx3 may functionally compensate for the loss of Panx1 in the VNO of the olfactory system, ensuring sustained chemosensory processing. This finding extends previous reports on the upregulation of Panx3 in arterial walls and the skin of Panx1 KO mice, suggesting that roles of Panx1 warrant uncharacterized safeguarding mechanisms involving Panx3.
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Affiliation(s)
- Paige Whyte-Fagundes
- Department of Biology, York University, Toronto, ON, Canada.,Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Stefan Kurtenbach
- Department of Biology, York University, Toronto, ON, Canada.,Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | | | - Valery I Shestopalov
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Peter L Carlen
- Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Georg Zoidl
- Department of Biology, York University, Toronto, ON, Canada.,Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Department of Psychology, York University, Toronto, ON, Canada
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77
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Abstract
Adenosine triphosphate (ATP) has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1), volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR) anion channels), and maxi-anion channels (MACs). Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.
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78
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Li S, Bjelobaba I, Stojilkovic SS. Interactions of Pannexin1 channels with purinergic and NMDA receptor channels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:166-173. [PMID: 28389204 PMCID: PMC5628093 DOI: 10.1016/j.bbamem.2017.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 12/31/2022]
Abstract
Pannexins are a three-member family of vertebrate plasma membrane spanning molecules that have homology to the invertebrate gap junction forming proteins, the innexins. However, pannexins do not form gap junctions but operate as plasma membrane channels. The best-characterized member of these proteins, Pannexin1 (Panx1) was suggested to be functionally associated with purinergic P2X and N-methyl-D-aspartate (NMDA) receptor channels. Activation of these receptor channels by their endogenous ligands leads to cross-activation of Panx1 channels. This in turn potentiates P2X and NMDA receptor channel signaling. Two potentiation concepts have been suggested: enhancement of the current responses and/or sustained receptor channel activation by ATP released through Panx1 pore and adenosine generated by ectonucleotidase-dependent dephosphorylation of ATP. Here we summarize the current knowledge and hypotheses about interactions of Panx1 channels with P2X and NMDA receptor channels. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Shuo Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Ivana Bjelobaba
- Institute for Biological Research "Sinisa Stankovic", University of Belgrade, 11000 Belgrade, Serbia
| | - Stanko S Stojilkovic
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
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79
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Synchronized roles of pannexin and connexin in nasal mucosal epithelia. Eur Arch Otorhinolaryngol 2018; 275:1657-1661. [PMID: 29574598 PMCID: PMC5951895 DOI: 10.1007/s00405-018-4947-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 03/20/2018] [Indexed: 01/07/2023]
Abstract
BACKGROUND Nasal mucosal epithelial cells express connexins, the prototypical gap junction proteins, and pannexins, a new family of channel proteins homologous to the invertebrate gap junction proteins. The physiological and pathophysiological roles of these transmembrane proteins in nasal mucosa are largely still unknown. PURPOSE Pannexins participate in ATP release into the extracellular space in various tissues, and ATP plays important roles in mucociliary clearance, especially by regulating ciliary beat activity. Therefore, we focused on the functional relationship between connexins, pannexin-1, ATP release, and mucociliary clearance in nasal epithelia. RESULTS AND CONCLUSIONS Connexins participate in the generation of intercellular calcium waves, in which calcium-mediated signaling responses spread to contiguous cells through the gap junction formed by connexins to transmit calcium signaling throughout the airway epithelium. Pannexins in the nasal mucosa may contribute to not only ciliary beat modulation via ATP release, but also regulation of mucus blanket components via H2O efflux. The synchronized roles of pannexin and connexin may provide a new insight into effective mucociliary clearance systems in nasal mucosa.
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80
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Galinsky R, Davidson JO, Dean JM, Green CR, Bennet L, Gunn AJ. Glia and hemichannels: key mediators of perinatal encephalopathy. Neural Regen Res 2018; 13:181-189. [PMID: 29557357 PMCID: PMC5879879 DOI: 10.4103/1673-5374.226378] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Perinatal encephalopathy remains a major cause of disability, such as cerebral palsy. Therapeutic hypothermia is now well established to partially reduce risk of disability in late preterm/term infants. However, new and complementary therapeutic targets are needed to further improve outcomes. There is increasing evidence that glia play a key role in neural damage after hypoxia-ischemia and infection/inflammation. In this review, we discuss the role of astrocytic gap junction (connexin) hemichannels in the spread of neural injury after hypoxia-ischemia and/or infection/inflammation. Potential mechanisms of hemichannel mediated injury likely involve impaired intracellular calcium handling, loss of blood-brain barrier integrity and release of adenosine triphosphate (ATP) resulting in over-activation of purinergic receptors. We propose the hypothesis that inflammation-induced opening of connexin hemichannels is a key regulating event that initiates a vicious cycle of excessive ATP release, which in turn propagates activation of purinergic receptors on microglia and astrocytes. This suggests that developing new neuroprotective strategies for preterm infants will benefit from a detailed understanding of glial and connexin hemichannel responses.
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Affiliation(s)
- Robert Galinsky
- Department of Physiology, University of Auckland, Auckland, New Zealand; The Ritchie Centre, Hudson Institute of Medical Research, Victoria, Australia
| | - Joanne O Davidson
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
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81
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Chiu YH, Schappe MS, Desai BN, Bayliss DA. Revisiting multimodal activation and channel properties of Pannexin 1. J Gen Physiol 2017; 150:19-39. [PMID: 29233884 PMCID: PMC5749114 DOI: 10.1085/jgp.201711888] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 11/09/2017] [Indexed: 12/23/2022] Open
Abstract
Pannexin 1 (Panx1) forms plasma membrane ion channels that are widely expressed throughout the body. Panx1 activation results in the release of nucleotides such as adenosine triphosphate and uridine triphosphate. Thus, these channels have been implicated in diverse physiological and pathological functions associated with purinergic signaling, such as apoptotic cell clearance, blood pressure regulation, neuropathic pain, and excitotoxicity. In light of this, substantial attention has been directed to understanding the mechanisms that regulate Panx1 channel expression and activation. Here we review accumulated evidence for the various activation mechanisms described for Panx1 channels and, where possible, the unitary channel properties associated with those forms of activation. We also emphasize current limitations in studying Panx1 channel function and propose potential directions to clarify the exciting and expanding roles of Panx1 channels.
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Affiliation(s)
- Yu-Hsin Chiu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
| | - Michael S Schappe
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
| | - Bimal N Desai
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
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82
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Regulation of Skeletal Muscle Myoblast Differentiation and Proliferation by Pannexins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 925:57-73. [PMID: 27518505 DOI: 10.1007/5584_2016_53] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Pannexins are newly discovered channels that are now recognized as mediators of adenosine triphosphate release from several cell types allowing communication with the extracellular environment. Pannexins have been associated with various physiological and pathological processes including apoptosis, inflammation, and cancer. However, it is only recently that our work has unveiled a role for Pannexin 1 and Pannexin 3 as novel regulators of skeletal muscle myoblast proliferation and differentiation. Myoblast differentiation is an ordered multistep process that includes withdrawal from the cell cycle and the expression of key myogenic factors leading to myoblast differentiation and fusion into multinucleated myotubes. Eventually, myotubes will give rise to the diverse muscle fiber types that build the complex skeletal muscle architecture essential for body movement, postural behavior, and breathing. Skeletal muscle cell proliferation and differentiation are crucial processes required for proper skeletal muscle development during embryogenesis, as well as for the postnatal skeletal muscle regeneration that is necessary for muscle repair after injury or exercise. However, defects in skeletal muscle cell differentiation and/or deregulation of cell proliferation are involved in various skeletal muscle pathologies. In this review, we will discuss the expression of pannexins and their post-translational modifications in skeletal muscle, their known functions in various steps of myogenesis, including myoblast proliferation and differentiation, as well as their possible roles in skeletal muscle development, regeneration, and diseases such as Duchenne muscular dystrophy.
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83
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Nomura T, Taruno A, Shiraishi M, Nakahari T, Inui T, Sokabe M, Eaton DC, Marunaka Y. Current-direction/amplitude-dependent single channel gating kinetics of mouse pannexin 1 channel: a new concept for gating kinetics. Sci Rep 2017; 7:10512. [PMID: 28874774 PMCID: PMC5585217 DOI: 10.1038/s41598-017-10921-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 08/16/2017] [Indexed: 11/25/2022] Open
Abstract
The detailed single-channel gating kinetics of mouse pannexin 1 (mPanx1) remains unknown, although mPanx1 is reported to be a voltage-activated anion-selective channel. We investigated characteristics of single-channel conductances and opening and closing rates of mPanx1 using patch-clamp techniques. The unitary current of mPanx1 shows outward rectification with single-channel conductances of ~20 pS for inward currents and ~80 pS for outward currents. The channel open time for outward currents (Cl- influx) increases linearly as the amplitude of single channel currents increases, while the open time for inward currents (Cl- efflux) is constant irrespective of changes in the current amplitude, as if the direction and amplitude of the unitary current regulates the open time. This is supported by further observations that replacement of extracellular Cl- with gluconate- diminishes the inward tail current (Cl- efflux) at a membrane potential of -100 mV due to the lowered outward current (gluconate- influx) at membrane potential of 100 mV. These results suggest that the direction and rate of charge-carrier movement regulate the open time of mPanx1, and that the previously reported voltage-dependence of Panx1 channel gating is not directly mediated by the membrane potential but rather by the direction and amplitude of currents through the channel.
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Affiliation(s)
- Takeshi Nomura
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
- Department of Bio-Ionomics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
- Department of Physical Therapy, Faculty of Rehabilitation, Kyushu Nutrition Welfare University, Kitakyushu, 800-0298, Japan
| | - Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
| | - Makoto Shiraishi
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
| | - Takashi Nakahari
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
- Department of Bio-Ionomics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
- Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, 602-8013, Japan
| | - Toshio Inui
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
- Department of Bio-Ionomics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan
- Saisei Mirai Clinics, Moriguchi, 570-0012, Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Douglas C Eaton
- Center for Cell & Molecular Signaling, Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, 30322, USA
| | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan.
- Department of Bio-Ionomics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, 602-8566, Japan.
- Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, 602-8013, Japan.
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84
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Gaitán-Peñas H, Gradogna A, Laparra-Cuervo L, Solsona C, Fernández-Dueñas V, Barrallo-Gimeno A, Ciruela F, Lakadamyali M, Pusch M, Estévez R. Investigation of LRRC8-Mediated Volume-Regulated Anion Currents in Xenopus Oocytes. Biophys J 2017; 111:1429-1443. [PMID: 27705766 PMCID: PMC5052465 DOI: 10.1016/j.bpj.2016.08.030] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/24/2016] [Accepted: 08/26/2016] [Indexed: 12/31/2022] Open
Abstract
Volume-regulated anion channels (VRACs) play an important role in controlling cell volume by opening upon cell swelling. Recent work has shown that heteromers of LRRC8A with other LRRC8 members (B, C, D, and E) form the VRAC. Here, we used Xenopus oocytes as a simple system to study LRRC8 proteins. We discovered that adding fluorescent proteins to the C-terminus resulted in constitutive anion channel activity. Using these constructs, we reproduced previous findings indicating that LRRC8 heteromers mediate anion and osmolyte flux with subunit-dependent kinetics and selectivity. Additionally, we found that LRRC8 heteromers mediate glutamate and ATP flux and that the inhibitor carbenoxolone acts from the extracellular side, binding to probably more than one site. Our results also suggest that the stoichiometry of LRRC8 heteromers is variable, with a number of subunits ≥6, and that the heteromer composition depends on the relative expression of different subunits. The system described here enables easy structure-function analysis of LRRC8 proteins.
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Affiliation(s)
- Héctor Gaitán-Peñas
- Unitat de Fisiología, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain; U-750, CIBERER, ISCIII, Spain
| | | | - Lara Laparra-Cuervo
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Carles Solsona
- Unitat de Neurobiologia, Departament Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat
| | - Victor Fernández-Dueñas
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat
| | - Alejandro Barrallo-Gimeno
- Unitat de Fisiología, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain; U-750, CIBERER, ISCIII, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat
| | - Melike Lakadamyali
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | | | - Raúl Estévez
- Unitat de Fisiología, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain; U-750, CIBERER, ISCIII, Spain.
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85
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Beyer EC, Berthoud VM. Gap junction gene and protein families: Connexins, innexins, and pannexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:5-8. [PMID: 28559187 DOI: 10.1016/j.bbamem.2017.05.016] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 05/18/2017] [Accepted: 05/25/2017] [Indexed: 02/08/2023]
Abstract
Gap junction channels facilitate the intercellular exchange of ions and small molecules. While this process is critical to all multicellular organisms, the proteins that form gap junction channels are not conserved. Vertebrate gap junctions are formed by connexins, while invertebrate gap junctions are formed by innexins. Interestingly, vertebrates and lower chordates contain innexin homologs, the pannexins, which also form channels, but rarely (if ever) make intercellular channels. While the connexin and the innexin/pannexin polypeptides do not share significant sequence similarity, all three of these protein families share a similar membrane topology and some similarities in quaternary structure. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States.
| | - Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States
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86
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Valdebenito S, Barreto A, Eugenin EA. The role of connexin and pannexin containing channels in the innate and acquired immune response. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:154-165. [PMID: 28559189 DOI: 10.1016/j.bbamem.2017.05.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 05/17/2017] [Accepted: 05/25/2017] [Indexed: 12/20/2022]
Abstract
Connexin (Cx) and pannexin (Panx) containing channels - gap junctions (GJs) and hemichannels (HCs) - are present in virtually all cells and tissues. Currently, the role of these channels under physiological conditions is well defined. However, their role in the immune response and pathological conditions has only recently been explored. Data from several laboratories demonstrates that infectious agents, including HIV, have evolved to take advantage of GJs and HCs to improve viral/bacterial replication, enhance inflammation, and help spread toxicity into neighboring areas. In the current review, we discuss the role of Cx and Panx containing channels in immune activation and the pathogenesis of several infectious diseases. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Silvana Valdebenito
- Public Health Research Institute (PHRI), Newark, NJ, USA; Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA
| | - Andrea Barreto
- Public Health Research Institute (PHRI), Newark, NJ, USA; Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA
| | - Eliseo A Eugenin
- Public Health Research Institute (PHRI), Newark, NJ, USA; Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA.
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87
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Xu J, Chen L, Li L. Pannexin hemichannels: A novel promising therapy target for oxidative stress related diseases. J Cell Physiol 2017; 233:2075-2090. [PMID: 28295275 DOI: 10.1002/jcp.25906] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 03/09/2017] [Indexed: 12/16/2022]
Abstract
Pannexins, which contain three subtypes: pannexin-1, -2, and -3, are vertebrate glycoproteins that form non-junctional plasma membrane intracellular hemichannels via oligomerization. Oxidative stress refers to an imbalance of the generation and elimination of reactive oxygen species (ROS). Studies have shown that elevated ROS levels are pivotal in the development of a variety of diseases. Recent studies indicate that the occurrence of these oxidative stress related diseases is associated with pannexin hemichannels. It is also reported that pannexins regulate the production of ROS which in turn may increase the opening of pannexin hemichannels. In this paper, we review recent researches about the important role of pannexin hemichannels in oxidative stress related diseases. Thus, pannexin hemichannels, novel therapeutic targets, hold promise in managing oxidative stress related diseases such as the tumor, inflammatory bowel diseases (IBD), pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), cardiovascular disease, insulin resistance (IR), and neural degeneration diseases.
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Affiliation(s)
- Jin Xu
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
| | - Linxi Chen
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
| | - Lanfang Li
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
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88
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Maes M, McGill MR, da Silva TC, Abels C, Lebofsky M, Weemhoff JL, Tiburcio T, Veloso Alves Pereira I, Willebrords J, Crespo Yanguas S, Farhood A, Beschin A, Van Ginderachter JA, Penuela S, Jaeschke H, Cogliati B, Vinken M. Inhibition of pannexin1 channels alleviates acetaminophen-induced hepatotoxicity. Arch Toxicol 2017; 91:2245-2261. [PMID: 27826632 PMCID: PMC5654513 DOI: 10.1007/s00204-016-1885-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/02/2016] [Indexed: 01/04/2023]
Abstract
Pannexins constitute a relatively new family of transmembrane proteins that form channels linking the cytoplasmic compartment with the extracellular environment. The presence of pannexin1 in the liver has been documented previously, where it underlies inflammatory responses, such as those occurring upon ischemia-reperfusion injury. In the present study, we investigated whether pannexin1 plays a role in acute drug-induced liver toxicity. Hepatic expression of pannexin1 was characterized in a mouse model of acetaminophen-induced hepatotoxicity. Subsequently, mice were overdosed with acetaminophen followed by treatment with the pannexin1 channel inhibitor 10Panx1. Sampling was performed 1, 3, 6, 24 and 48 h after acetaminophen administration. Evaluation of the effects of pannexin1 channel inhibition was based on a number of clinically relevant readouts, including protein adduct formation, measurement of aminotransferase activity and histopathological examination of liver tissue as well as on a series of markers of inflammation, oxidative stress and regeneration. Although no significant differences were found in histopathological analysis, pannexin1 channel inhibition reduced serum levels of alanine and aspartate aminotransferase. This was paralleled by a reduced amount of neutrophils recruited to the liver. Furthermore, alterations in the oxidized status were noticed with upregulation of glutathione levels upon suppression of pannexin1 channel opening. Concomitant promotion of regenerative activity was detected as judged on increased proliferating cell nuclear antigen protein quantities in 10Panx1-treated mice. Pannexin1 channels are important actors in liver injury triggered by acetaminophen. Inhibition of pannexin1 channel opening could represent a novel approach for the treatment of drug-induced hepatotoxicity.
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Affiliation(s)
- Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Mitchell R McGill
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - Tereza Cristina da Silva
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Chloé Abels
- Myeloid Cell Immunology Lab, VIB Inflammation Research Center, Ghent, Belgium
- Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Margitta Lebofsky
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - James L Weemhoff
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Taynã Tiburcio
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Isabel Veloso Alves Pereira
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Anwar Farhood
- Department of Pathology, St. David's North Austin Medical Center, Austin, TX, USA
| | - Alain Beschin
- Myeloid Cell Immunology Lab, VIB Inflammation Research Center, Ghent, Belgium
- Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jo A Van Ginderachter
- Myeloid Cell Immunology Lab, VIB Inflammation Research Center, Ghent, Belgium
- Lab of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Canada
| | - Hartmut Jaeschke
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
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89
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Molica F, Stierlin FB, Fontana P, Kwak BR. Pannexin- and Connexin-Mediated Intercellular Communication in Platelet Function. Int J Mol Sci 2017; 18:E850. [PMID: 28420171 PMCID: PMC5412434 DOI: 10.3390/ijms18040850] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/06/2017] [Accepted: 04/12/2017] [Indexed: 12/11/2022] Open
Abstract
The three major blood cell types, i.e., platelets, erythrocytes and leukocytes, are all produced in the bone marrow. While red blood cells are the most numerous and white cells are the largest, platelets are small fragments and account for a minor part of blood volume. However, platelets display a crucial function by preventing bleeding. Upon vessel wall injury, platelets adhere to exposed extracellular matrix, become activated, and form a platelet plug preventing hemorrhagic events. However, when platelet activation is exacerbated, as in rupture of an atherosclerotic plaque, the same mechanism may lead to acute thrombosis causing major ischemic events such as myocardial infarction or stroke. In the past few years, major progress has been made in understanding of platelet function modulation. In this respect, membrane channels formed by connexins and/or pannexins are of particular interest. While it is still not completely understood whether connexins function as hemichannels or gap junction channels to inhibit platelet aggregation, there is clear-cut evidence for a specific implication of pannexin1 channels in collagen-induced aggregation. The focus of this review is to summarize current knowledge of the role of connexins and pannexins in platelet aggregation and to discuss possible pharmacological approaches along with their limitations and future perspectives for new potential therapies.
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Affiliation(s)
- Filippo Molica
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland.
- Department of Medical Specializations, Cardiology, University of Geneva, 1211 Geneva, Switzerland.
| | - Florian B Stierlin
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland.
- Department of Medical Specializations, Cardiology, University of Geneva, 1211 Geneva, Switzerland.
- Geneva Platelet Group, University of Geneva, 1211 Geneva, Switzerland.
| | - Pierre Fontana
- Geneva Platelet Group, University of Geneva, 1211 Geneva, Switzerland.
- Division of Angiology and Haemostasis, Geneva University Hospitals, 1211 Geneva, Switzerland.
| | - Brenda R Kwak
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland.
- Department of Medical Specializations, Cardiology, University of Geneva, 1211 Geneva, Switzerland.
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90
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Kim Y, Davidson JO, Green CR, Nicholson LFB, O'Carroll SJ, Zhang J. Connexins and Pannexins in cerebral ischemia. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:224-236. [PMID: 28347700 DOI: 10.1016/j.bbamem.2017.03.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/24/2017] [Accepted: 03/22/2017] [Indexed: 12/12/2022]
Abstract
A common cause of mortality and long-term adult disability, cerebral ischemia or brain ischemia imposes a significant health and financial burden on communities worldwide. Cerebral ischemia is a condition that arises from a sudden loss of blood flow and consequent failure to meet the high metabolic demands of the brain. The lack of blood flow initiates a sequelae of cell death mechanisms, including the activation of the inflammatory pathway, which can ultimately result in irreversible brain tissue damage. In particular, Connexins and Pannexins are non-selective channels with a large pore that have shown to play time-dependent roles in the perpetuation of ischaemic injury. This review highlights the roles of Connexin and Pannexin channels in cell death mechanisms as a promising therapeutic target in cerebral ischemia, and in particular connexin hemichannels which may contribute most of the ATP release as a result of ischemia as well as during reperfusion. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Yeri Kim
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland
| | - Joanne O Davidson
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland
| | - Colin R Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland
| | - Louise F B Nicholson
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland
| | - Simon J O'Carroll
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland
| | - Jie Zhang
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland.
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91
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Scemes E, Velíšková J. Exciting and not so exciting roles of pannexins. Neurosci Lett 2017; 695:25-31. [PMID: 28284836 DOI: 10.1016/j.neulet.2017.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/02/2017] [Accepted: 03/06/2017] [Indexed: 01/24/2023]
Abstract
It is the current view that purinergic signaling regulates many physiological functions. Pannexin1 (Panx1), a member of the gap junction family of proteins is an ATP releasing channel that plays important physio-pathological roles in various tissues, including the CNS. Upon binding to purinergic receptors expressed in neural cells, ATP triggers cellular responses including increased cell proliferation, cell morphology changes, release of cytokines, and regulation of neuronal excitability via release of glutamate, GABA and ATP itself. Under pathological conditions such as ischemia, trauma, inflammation, and epilepsy, extracellular ATP concentrations increases drastically but the consequences of this surge is still difficult to characterize due to its rapid metabolism in ADP and adenosine, the latter having inhibitory action on neuronal activity. For seizures, for instance, the excitatory effect of ATP on neuronal activity is mainly related to its action of P2X receptors, while the inhibitory effects are related to activation of P1, adenosine receptors. Here we provide a mini review on the properties of pannexins with a main focus on Panx1 and its involvement in seizure activity. Although there are only few studies implicating Panx1 in seizures, they are illustrative of the dual role that Panx1 has on neuronal excitability.
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Affiliation(s)
- Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Jana Velíšková
- Departments of Cell Biology & Anatomy, Obstetrics & Gynecology and Neurology, New York Medical College, Valhalla, NY, 10595, USA.
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92
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Boyce AKJ, Epp AL, Nagarajan A, Swayne LA. Transcriptional and post-translational regulation of pannexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:72-82. [PMID: 28279657 DOI: 10.1016/j.bbamem.2017.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 12/21/2022]
Abstract
Pannexins are a 3-membered family of proteins that form large pore ion and metabolite channels in vertebrates. The impact of pannexins on vertebrate biology is intricately tied to where and when they are expressed, and how they are modified, once produced. The purpose of this review is therefore to outline our current understanding of transcriptional and post-translational regulation of pannexins. First, we briefly summarize their discovery and characteristics. Next, we describe several aspects of transcriptional regulation, including cell and tissue-specific expression, dynamic expression over development and disease, as well as new insights into the underlying molecular machinery involved. Following this, we delve into the role of post-translational modifications in the regulation of trafficking and channel properties, highlighting important work on glycosylation, phosphorylation, S-nitrosylation and proteolytic cleavage. Embedded throughout, we also highlight important knowledge gaps and avenues of future research. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Andrew K J Boyce
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada
| | - Anna L Epp
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada
| | - Archana Nagarajan
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada
| | - Leigh Anne Swayne
- Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria V8P 5C2, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver V6T 1Z3, Canada.
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93
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A quantized mechanism for activation of pannexin channels. Nat Commun 2017; 8:14324. [PMID: 28134257 PMCID: PMC5290276 DOI: 10.1038/ncomms14324] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 12/16/2016] [Indexed: 11/18/2022] Open
Abstract
Pannexin 1 (PANX1) subunits form oligomeric plasma membrane channels that mediate nucleotide release for purinergic signalling, which is involved in diverse physiological processes such as apoptosis, inflammation, blood pressure regulation, and cancer progression and metastasis. Here we explore the mechanistic basis for PANX1 activation by using wild type and engineered concatemeric channels. We find that PANX1 activation involves sequential stepwise sojourns through multiple discrete open states, each with unique channel gating and conductance properties that reflect contributions of the individual subunits of the hexamer. Progressive PANX1 channel opening is directly linked to permeation of ions and large molecules (ATP and fluorescent dyes) and occurs during both irreversible (caspase cleavage-mediated) and reversible (α1 adrenoceptor-mediated) forms of channel activation. This unique, quantized activation process enables fine tuning of PANX1 channel activity and may be a generalized regulatory mechanism for other related multimeric channels. Pannexins are oligomeric plasma membrane channels that allow permeation of ions and large molecules. Here the authors show that human Pannexin 1 activation is a multistep event, where modification of each monomer opens the channel to a unique conductance state and fine tunes its activity.
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94
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Crespo Yanguas S, Willebrords J, Johnstone SR, Maes M, Decrock E, De Bock M, Leybaert L, Cogliati B, Vinken M. Pannexin1 as mediator of inflammation and cell death. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:51-61. [PMID: 27741412 DOI: 10.1016/j.bbamcr.2016.10.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 10/07/2016] [Accepted: 10/08/2016] [Indexed: 02/06/2023]
Abstract
Pannexins form channels at the plasma membrane surface that establish a pathway for communication between the cytosol of individual cells and their extracellular environment. By doing so, pannexin signaling dictates several physiological functions, but equally underlies a number of pathological processes. Indeed, pannexin channels drive inflammation by assisting in the activation of inflammasomes, the release of pro-inflammatory cytokines, and the activation and migration of leukocytes. Furthermore, these cellular pores facilitate cell death, including apoptosis, pyroptosis and autophagy. The present paper reviews the roles of pannexin channels in inflammation and cell death. In a first part, a state-of-the-art overview of pannexin channel structure, regulation and function is provided. In a second part, the mechanisms behind their involvement in inflammation and cell death are discussed.
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Affiliation(s)
- Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Scott R Johnstone
- College of Medical, Veterinary and Life Sciences, British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Ghent University, Gent, Belgium
| | - Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Ghent University, Gent, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Ghent University, Gent, Belgium
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium.
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95
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Plotkin LI, Laird DW, Amedee J. Role of connexins and pannexins during ontogeny, regeneration, and pathologies of bone. BMC Cell Biol 2016; 17 Suppl 1:19. [PMID: 27230612 PMCID: PMC4896274 DOI: 10.1186/s12860-016-0088-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Electron micrographs revealed the presence of gap junctions in osteoblastic cells over 40 years ago. These intercellular channels formed from connexins are present in bone forming osteoblasts, bone resorbing osteoclasts, and osteocytes (mature osteoblasts embedded in the mineralized bone matrix). More recently, genetic and pharmacologic studies revealed the role of connexins, and in particular Cx43, in the differentiation and function of all bone types. Furthermore, mutations in the gene encoding Cx43 were found to be causally linked to oculodentodigital dysplasia, a condition that results in an abnormal skeleton. Pannexins, molecules with similar structure and single-membrane channel forming potential as connexins when organized as hemichannels, are also expressed in osteoblastic cells. The function of pannexins in bone and cartilage is beginning to be uncovered, but more research is needed to determine the role of pannexins in bone development, adult bone mass and skeletal homeostasis. We describe here the current knowledge on the role of connexins and pannexins on skeletal health and disease.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Roudebush Veterans Administration Medical Center Indiana, Indianapolis, IN, 46202, USA.
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, N6A-5C1, Canada
| | - Joelle Amedee
- INSERM U1026, Tissue Bioengineering, Université Bordeaux, Bordeaux, F-33076, France
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96
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Abstract
Pannexin (Panx) is a gene family encoding gap junction proteins in vertebrates. So far, three isoforms (Panx1, 2 and 3) have been identified. All of three Panx isoforms express in the cochlea with distinct expression patterns. Panx1 expresses in the cochlea extensively, including the spiral limbus, the organ of Corti, and the cochlear lateral wall, whereas Panx2 and Panx3 restrict to the basal cells of the stria vascularis in the lateral wall and the cochlear bony structure, respectively. However, there is no pannexin expression in auditory sensory hair cells. Recent studies demonstrated that like connexin gap junction gene, Panx1 deficiency causes hearing loss. Panx1 channels dominate ATP release in the cochlea. Deletion of Panx1 abolishes ATP release in the cochlea and reduces endocochlear potential (EP), auditory receptor current/potential, and active cochlear amplification. Panx1 deficiency in the cochlea also activates caspase-3 cell apoptotic pathway leading to cell degeneration. These new findings suggest that pannexins have a critical role in the cochlea in regard to hearing. However, detailed information about pannexin function in the cochlea and Panx mutation induced hearing loss still remain largely undetermined. Further studies are required.
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Affiliation(s)
- Hong-Bo Zhao
- Department of Otolaryngology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY, 40536, USA.
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97
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Abstract
Communication among cells via direct cell-cell contact by connexin gap junctions, or between cell and extracellular environment via pannexin channels or connexin hemichannels, is a key factor in cell function and tissue homeostasis. Upon malignant transformation in different cancer types, the dysregulation of these connexin and pannexin channels and their effect in cellular communication, can either enhance or suppress tumorigenesis and metastasis. In this review, we will highlight the latest reports on the role of the well characterized connexin family and its ability to form gap junctions and hemichannels in cancer. We will also introduce the more recently discovered family of pannexin channels and our current knowledge about their involvement in cancer progression.
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Affiliation(s)
- Jean X Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, N6A5C1, Canada.
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98
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Loss of Panx1 Impairs Mammary Gland Development at Lactation: Implications for Breast Tumorigenesis. PLoS One 2016; 11:e0154162. [PMID: 27099931 PMCID: PMC4839729 DOI: 10.1371/journal.pone.0154162] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 04/08/2016] [Indexed: 12/03/2022] Open
Abstract
Pannexin1 (Panx1) subunits oligomerize to form large-pore channels between the intracellular and extracellular milieu that have been shown to regulate proliferation, differentiation and cell death mechanisms. These key cellular responses are ultimately necessary for normal tissue development and function but the role of Panx1 in development, differentiation and function in many tissues remains unexplored, including that of the breast. Panx1 was identified to be expressed in the mammary gland through western blot and immunofluorescent analysis and is dynamically upregulated during pregnancy and lactation. In order to evaluate the role of Panx1 in the context of mammary gland development and function, Panx1-/- mice were evaluated in comparison to wild-type mice in the mammary glands of virgin, lactating and involuting mice. Our results revealed that Panx1 ablation did not affect virgin or involuting mammary glands following histological and whole mount analysis. Panx1 was necessary for timely alveolar development during early lactation based on a decreased number of alveolar lumen following histological analysis and reduced proliferation following Ki67 immunofluorescent labelling. Importantly, the loss of Panx1 in lactating mammary glands did not overtly affect epithelial or secretory differentiation of the mammary gland suggesting that Panx1 is not critical in normal mammary gland function. In addition, PANX1 mRNA expression was correlated with negative clinical outcomes in patients with breast cancer using in silico arrays. Together, our results suggest that Panx1 is necessary for timely alveolar development following the transition from pregnancy to lactation, which may have implications extending to patients with breast cancer.
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99
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Shao Q, Lindstrom K, Shi R, Kelly J, Schroeder A, Juusola J, Levine KL, Esseltine JL, Penuela S, Jackson MF, Laird DW. A Germline Variant in the PANX1 Gene Has Reduced Channel Function and Is Associated with Multisystem Dysfunction. J Biol Chem 2016; 291:12432-12443. [PMID: 27129271 DOI: 10.1074/jbc.m116.717934] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 12/20/2022] Open
Abstract
Pannexin1 (PANX1) is probably best understood as an ATP release channel involved in paracrine signaling. Given its ubiquitous expression, PANX1 pathogenic variants would be expected to lead to disorders involving multiple organ systems. Using whole exome sequencing, we discovered the first patient with a homozygous PANX1 variant (c.650G→A) resulting in an arginine to histidine substitution at position 217 (p.Arg217His). The 17-year-old female has intellectual disability, sensorineural hearing loss requiring bilateral cochlear implants, skeletal defects, including kyphoscoliosis, and primary ovarian failure. Her consanguineous parents are each heterozygous for this variant but are not affected by the multiorgan syndromes noted in the proband. Expression of the p.Arg217His mutant in HeLa, N2A, HEK293T, and Ad293 cells revealed normal PANX1 glycosylation and cell surface trafficking. Dye uptake, ATP release, and electrophysiological measurements revealed p.Arg217His to be a loss-of-function variant. Co-expression of the mutant with wild-type PANX1 suggested the mutant was not dominant-negative to PANX1 channel function. Collectively, we demonstrate a PANX1 missense change associated with human disease in the first report of a "PANX1-related disorder."
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Affiliation(s)
- Qing Shao
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Kristin Lindstrom
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, Arizona 85016
| | - Ruoyang Shi
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0Z3, Canada,; Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba R3E 0Z3, Canada
| | - John Kelly
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Audrey Schroeder
- Division of Genetics, University of Rochester Medical Center, Rochester, New York 14642
| | | | | | - Jessica L Esseltine
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Michael F Jackson
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0Z3, Canada,; Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba R3E 0Z3, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada.
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100
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Velasquez S, Malik S, Lutz SE, Scemes E, Eugenin EA. Pannexin1 Channels Are Required for Chemokine-Mediated Migration of CD4+ T Lymphocytes: Role in Inflammation and Experimental Autoimmune Encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2016; 196:4338-47. [PMID: 27076682 DOI: 10.4049/jimmunol.1502440] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/09/2016] [Indexed: 12/19/2022]
Abstract
Pannexin1 (Panx1) channels are large high conductance channels found in all vertebrates that can be activated under several physiological and pathological conditions. Our published data indicate that HIV infection results in the extended opening of Panx1 channels (5-60 min), allowing for the secretion of ATP through the channel pore with subsequent activation of purinergic receptors, which facilitates HIV entry and replication. In this article, we demonstrate that chemokines, which bind CCR5 and CXCR4, especially SDF-1α/CXCL12, result in a transient opening (peak at 5 min) of Panx1 channels found on CD4(+) T lymphocytes, which induces ATP secretion, focal adhesion kinase phosphorylation, cell polarization, and subsequent migration. Increased migration of immune cells is key for the pathogenesis of several inflammatory diseases including multiple sclerosis (MS). In this study, we show that genetic deletion of Panx1 reduces the number of the CD4(+) T lymphocytes migrating into the spinal cord of mice subjected to experimental autoimmune encephalomyelitis, an animal model of MS. Our results indicate that opening of Panx1 channels in response to chemokines is required for CD4(+) T lymphocyte migration, and we propose that targeting Panx1 channels could provide new potential therapeutic approaches to decrease the devastating effects of MS and other inflammatory diseases.
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Affiliation(s)
- Stephani Velasquez
- Public Health Research Institute, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103; Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103
| | - Shaily Malik
- Public Health Research Institute, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103; Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103
| | - Sarah E Lutz
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697; and
| | - Eliana Scemes
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Eliseo A Eugenin
- Public Health Research Institute, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103; Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ 07103;
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