Genomes and Genes
Gating of Connexin-Based Gap Junction Channels and Hemichannels
Principal Investigator: Feliksas Bukauskas
Abstract: DESCRIPTION (provided by applicant): The main goal of these studies is to elucidate the mechanisms underlying voltage- and intracellular pHi- dependent gating of connexin(Cx)-based gap junction (GJ) channels and unapposed hemi channels (uHCs). pHi is a fundamental modulator of cell function that influences various physiological processes such as metabolism, proliferation, function of membrane channels and transporters, cell movement and contractility. pHi can change considerably during pathological processes, most often during ischemia, and H+ ions have been shown to have broad effects on electrical and metabolic cell-cell communication through GJs and paracrine signaling through uHCs. Sp. Aim 1 focuses on pHi-dependent modulation of gating by transjunctional voltage (Vj) in homotypic GJs. We have shown that each hemi channel within a GJ channel has two distinct gating mechanisms, termed fast and slow gates, that are sensitive to Vj and distinguished by the channel closure to a substate and fully, respectively. We will test the hypothesis that dynamic pHi-mediated changes in gj with modest acidification occur through modulation of the Vj sensitivity of the fast gate in a Cx- type dependent manner, while stronger acidification leads to full uncoupling in all Cxs due to the closure of the slow gate without changes in the sensitivity to Vj. We will test the hypothesis that acidification-mediated full uncoupling is due to transition of the slow gate from a closed to a deep-closed state that can be accelerated by applied Vjs and by chemical uncouplers. Sp. Aim 2 focuses on pHi-dependent modulation of Vj-gating in heterotypic GJs formed in tissues co-expressing several Cx isoforms. In heterotypic GJs, acidification-induced uncoupling is defined mainly by the Cx exhibiting higher sensitivity to pHi allowing to test at higher resolution than in homotypic GJs that indeed pHi-dependent gating is hemi channel-based and that fast and slow gates play different roles in pHi-dependent regulation of cell-cell coupling. We will test the hypothesis that the NT-M1 domain of Cx is directly involved in Vj- and pHi-dependent gating as suggested by our data from Cx43*mCx30.2 chimeras. Sp. Aim 3 focuses on pHi-dependent gating of uHCs. We will test the hypothesis that pH-dependent modulation of Vj-gating observed in GJ channels has a common background with voltage- gating of uHCs, i.e., alkalization reduces and acidification increases voltage-sensitive gating of uHCs. We will identify residues in the NT-M1 domain that affect unitary conductance, sensitivity to voltage and permeability to dyes of uHCs. We will test the hypothesis that the pH sensor of uHCs is on the cytoplasmic side as we have reported earlier for Cx46 uHCs. Comparison of Vj- and pHi-dependent gating properties among uHCs and corresponding GJ channels will advance our knowledge as to what extent docking of uHCs alters biophysical properties of GJs. In Sp. Aims 1 and 3, we will test whether Vj- and pH-dependent gating is associated with a change in calmodulin (CaM) co-localization with GJs and whether CaM influences the interaction between H+ ions and gating elements of slow and fast gates of GJs and uHCs.
Funding Period: 2010-09-01 - 2014-06-30
more information: NIH RePORT
- FGF-1 induces ATP release from spinal astrocytes in culture and opens pannexin and connexin hemichannelsJuan M Garré
Facultad de Medicina, Universidad de la República Oriental del Uruguay, C P 11800 Montevideo, Uruguay
Proc Natl Acad Sci U S A 107:22659-64. 2010..These changes in HCs and gap junction channels may promote inflammation and deprive neurons of astrocyte-mediated protection in spinal cord trauma and neurodegenerative disease...
- The Connexin40A96S mutation from a patient with atrial fibrillation causes decreased atrial conduction velocities and sustained episodes of induced atrial fibrillation in miceIndra Lübkemeier
Life and Medical Sciences LIMES Institute, Molecular Genetics, University of Bonn, Bonn, Germany
J Mol Cell Cardiol 65:19-32. 2013..We conclude that heterozygous Cx40A96S mice exhibit prolonged episodes of induced atrial fibrillation and severely reduced atrial conduction velocities similar to the corresponding human patient. ..
- Molecular and functional asymmetry at a vertebrate electrical synapseJohn E Rash
Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
Neuron 79:957-69. 2013....
- Deletion of the last five C-terminal amino acid residues of connexin43 leads to lethal ventricular arrhythmias in mice without affecting coupling via gap junction channelsIndra Lübkemeier
Life and Medical Sciences LIMES Institute, Molecular Genetics, University of Bonn, Carl Troll Str 31, 53115, Bonn, Germany
Basic Res Cardiol 108:348. 2013..The Cx43D378stop mice reveal for the first time that Cx43 dependent arrhythmias can develop by mechanisms other than impairment of gap junction channel function...
- Intracellular magnesium-dependent modulation of gap junction channels formed by neuronal connexin36Nicolas Palacios-Prado
Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA
J Neurosci 33:4741-53. 2013..Thus, this novel modulatory mechanism could underlie changes in neuronal synchronization under conditions in which ATP levels, and consequently [Mg(2+)]i, are modified...
- Regulation of connexin36 gap junction channels by n-alkanols and arachidonic acidAlina Marandykina
Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
J Physiol 591:2087-101. 2013..In addition, SCCAs increase gj by interfering with endogenous AA-dependent inhibition, increasing open probability and the fraction of functional channels...
- Selective inhibition of Cx43 hemichannels by Gap19 and its impact on myocardial ischemia/reperfusion injuryNan Wang
Faculty of Medicine and Health Sciences, Physiology Group, Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
Basic Res Cardiol 108:309. 2013..We conclude that preventing Cx43 hemichannel opening with Gap19 confers limited protective effects against myocardial ischemia/reperfusion injury...
- Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca2+ elevationNan Wang
Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Belgium
Basic Res Cardiol 107:304. 2012..Our results indicate that under pathological conditions, when [Ca(2+)](i) is elevated, Cx43 HC opening is promoted in cardiomyocytes and CxMPs counteract this effect...
- Connexin and pannexin hemichannels in inflammatory responses of glia and neuronsMichael V L Bennett
Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
Brain Res 1487:3-15. 2012..These studies implicate two kinds of gap junction hemichannel in inflammatory responses and cell death. This article is part of a Special Issue entitled Electrical Synapses...
- Paracrine signaling through plasma membrane hemichannelsNan Wang
Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
Biochim Biophys Acta 1828:35-50. 2013..This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions...
- Neurons and β-cells of the pancreas express connexin36, forming gap junction channels that exhibit strong cationic selectivityFeliksas F Bukauskas
Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
J Membr Biol 245:243-53. 2012..Thus, Cx36 GJs are highly cation-selective and should exhibit relatively low permeability to numerous vital negatively charged metabolites and high permeability to K⁺, a major charge carrier in cell-cell communication...
- Stochastic 16-state model of voltage gating of gap-junction channels enclosing fast and slow gatesNerijus Paulauskas
Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, New York, USA
Biophys J 102:2471-80. 2012....
- The role of gap junction channels during physiologic and pathologic conditions of the human central nervous systemEliseo A Eugenin
Department of Pathology, F727, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA
J Neuroimmune Pharmacol 7:499-518. 2012..The focus of this review is to summarize recent findings related to the role of GJs and uHC in physiologic and pathologic conditions of the central nervous system...
- Modulation of metabolic communication through gap junction channels by transjunctional voltage; synergistic and antagonistic effects of gating and ionophoresisNicolas Palacios-Prado
Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
Biochim Biophys Acta 1818:1884-94. 2012..This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics...
- pH-dependent modulation of connexin-based gap junctional uncouplersVytenis A Skeberdis
Lithuanian University of Health Sciences, Institute of Cardiology, 17 Sukilėliųu Avenue, Kaunas 50009, Lithuania
J Physiol 589:3495-506. 2011..This suggests that LCCAs and some other uncouplers may act through the formation of hydrogen bonds with the as-of-yet unidentified histidine/s of the Cx45 GJ channel protein...
- Fast structural responses of gap junction membrane domains to AB5 toxinsIrina V Majoul
Institute of Biology, Center for Structural and Cell Biology in Medicine, University of Lubeck, 23562 Lübeck, Germany
Proc Natl Acad Sci U S A 110:E4125-33. 2013..Our data demonstrate very fast dynamics (in the millisecond-to-second range) within GJ plaques, which previously were considered to be relatively stable, long-lived structures...
- Connexin Distribution in Physiological Versus Pathological Cardiac HypertrophyMichael R Zile; Fiscal Year: 2013..pathological hypertrophy, with ex- tensively characterized cytoskeletal properties in each setting. ..
- GAP JUNCTIONS AND IONIC CURRENTS IN DEVELOPING HEARTJenny J Yang; Fiscal Year: 2013..These combined experimental approaches will identify new molecular targets on the connexin proteins for the possible pharmacological modulation of cardiac electrical communication by new therapeutic agents. ..
- CONNEXONS IN CARDIOVASCULAR CELL COMMUNICATIONEric C Beyer; Fiscal Year: 2013..Disturbances of electrical conduction lead to abnormal heart rhythms such as atrial fibrillation. Our studies will clarify how abnormalities of the subunit gap junction proteins lead to arrhythmias such as atrial fibrillation. ..
- Strategies for Improved Shock Wave LithotripsyJAMES ALEXANDER MCATEER; Fiscal Year: 2013..and the session can be ended * Determine the mechanism by which cavitation within a vessel causes hemorrhage * Develop numerical models to understand the role of cavitation and non-cavitational mechanisms in causing tissue damage ..
- MICROVASCULAR TRANSPORT IN THE RENAL MEDULLAThomas L Pallone; Fiscal Year: 2013..Regulation of contraction and dilation of descending vasa recta is a vital physiological process and is the subject of study in this proposal. PROJECT/ ..
- STRUCTURAL ANALYSIS OF GAP JUNCTION TRAFFICKINGGina E Sosinsky; Fiscal Year: 2013..We investigate the connexin43 trafficking process using an imaging based approach examining the hierarchy of connexin43 phosphorylation events and where within the cell cycle, connexin43-kinase(s) interactions occurs. ..
- Making Sense of Voltage SensorsStephen H White; Fiscal Year: 2013..His work focuses directly on the molecular basis of voltage sensor domains and their interactions with VSD-blocking toxins...
- STRUCTURE AND DYNAMICS OF CONNEXIN26 GAP JUNCTIONSGina E Sosinsky; Fiscal Year: 2013..The proposed research is significant because results will be useful in defining better drugs and other therapeutics that potentially ameliorate connexin-related diseases. ..
- Structure and Dynamics of Gap Junction ChannelsMARK JAY YEAGER; Fiscal Year: 2013..Such a detailed molecular picture will provide insight into how these channels are involved in such diverse processes as regulating the heartbeat and hereditary deafness. ..
- Protein Dynamics in Enzymatic CatalysisRobert Callender; Fiscal Year: 2013..The Equipment Core (Core A) supports the specialized comprehensive suite of instrumentation for the Program. The Administrative Core (Core B) administers the Program Project. ..
- Cyclic nucleotide permeability of connexin mutants related to genetic diseaseVirginijus Valiunas; Fiscal Year: 2013..The results of the proposed research will establish a baseline for understanding the role of perm-selectivity as a potential determinant of disease states such as oculodentodigital dysplasia and atrial fibrillation. ..
- Interactive Signaling Modules in Vascular InflammationLinda H Shapiro; Fiscal Year: 2013..abstract_text> ..
- Photonic probe and techniques for biological imaging applicationsWen Hong Li; Fiscal Year: 2013..New probes and methods developed here should have broad applications in cellular and neuronal biology and in different biological systems. ..
- Regulation of Cx26 and Cx32 Channels by Cytosolic Interdomain InteractionsAndrew L Harris; Fiscal Year: 2013....
- Integration and Arrhythmia Suppression with hESC-Derived Cardiomyocyte GraftsMICHAEL ALAN LAFLAMME; Fiscal Year: 2013..Finally, in Aim 3, we will use in vitro models to develop Wnt5a-mediated chemotaxis as a complementary strategy to improve the integration of hESC-CM grafts. ..