1
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Fakhar M, Najumuddin, Zahid S, Rashid S. Structural basis of Klotho binding to VEGFR2 and TRPC1 and repurposing calcium channel blockers as TRPC1 antagonists for the treatment of age-related cardiac hypertrophy. Arch Biochem Biophys 2022; 719:109171. [DOI: 10.1016/j.abb.2022.109171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 12/13/2021] [Accepted: 02/28/2022] [Indexed: 11/15/2022]
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2
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Naulin PA, Lozano B, Fuentes C, Liu Y, Schmidt C, Contreras JE, Barrera NP. Polydisperse molecular architecture of connexin 26/30 heteromeric hemichannels revealed by atomic force microscopy imaging. J Biol Chem 2020; 295:16499-16509. [PMID: 32887797 PMCID: PMC7864052 DOI: 10.1074/jbc.ra119.012128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 08/31/2020] [Indexed: 11/06/2022] Open
Abstract
Connexin (Cx) protein forms hemichannels and gap junctional channels, which play diverse and profound roles in human physiology and diseases. Gap junctions are arrays of intercellular channels formed by the docking of two hemichannels from adjacent cells. Each hexameric hemichannel contains the same or different Cx isoform. Although homomeric Cxs forms have been largely described functionally and structurally, the stoichiometry and arrangement of heteromeric Cx channels remain unknown. The latter, however, are widely expressed in human tissues and variation might have important implications on channel function. Investigating properties of heteromeric Cx channels is challenging considering the high number of potential subunit arrangements and stoichiometries, even when only combining two Cx isoforms. To tackle this problem, we engineered an HA tag onto Cx26 or Cx30 subunits and imaged hemichannels that were liganded by Fab-epitope antibody fragments via atomic force microscopy. For Cx26-HA/Cx30 or Cx30-HA/Cx26 heteromeric channels, the Fab-HA binding distribution was binomial with a maximum of three Fab-HA bound. Furthermore, imaged Cx26/Cx30-HA triple liganded by Fab-HA showed multiple arrangements that can be derived from the law of total probabilities. Atomic force microscopy imaging of ringlike structures of Cx26/Cx30-HA hemichannels confirmed these findings and also detected a polydisperse distribution of stoichiometries. Our results indicate a dominant subunit stoichiometry of 3Cx26:3Cx30 with the most abundant subunit arrangement of Cx26-Cx26-Cx30-Cx26-Cx30-Cx30. To our knowledge, this is the first time that the molecular architecture of heteromeric Cx channels has been revealed, thus providing the basis to explore the functional effect of these channels in biology.
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Affiliation(s)
- Pamela A Naulin
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Benjamin Lozano
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Christian Fuentes
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Yu Liu
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Carla Schmidt
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Jorge E Contreras
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Nelson P Barrera
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
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3
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Vangeel L, Voets T. Transient Receptor Potential Channels and Calcium Signaling. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035048. [PMID: 30910771 DOI: 10.1101/cshperspect.a035048] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transient receptor potential (TRP) cation channels play diverse roles in cellular Ca2+ signaling. First, as Ca2+-permeable channels that respond to a variety of stimuli, TRP channels can directly initiate cellular Ca2+ signals. Second, as nonselective cation channels, TRP channel activation leads to membrane depolarization, influencing Ca2+ influx via voltage-gated and store-operated Ca2+ channels. Finally, Ca2+ modulates the activity of most TRP channels, allowing them to function as molecular effectors downstream of intracellular Ca2+ signals. Whereas the TRP channel field has long been devoid of detailed channel structures, recent advances, particularly in cryo-electron microscopy-based structural approaches, have yielded a flurry of TRP channel structures, including members from all seven subfamilies. These structures, in conjunction with mutagenesis-based functional approaches, provided important new insights into the mechanisms whereby TRP channels permeate and sense Ca2+ These insights will be highly instrumental in the rational design of novel treatments for the multitude of TRP channel-related diseases.
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Affiliation(s)
- Laura Vangeel
- Laboratory of Ion Channel Research, VIB Center for Brain and Disease Research & Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Thomas Voets
- Laboratory of Ion Channel Research, VIB Center for Brain and Disease Research & Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
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4
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Minard A, Bauer CC, Wright DJ, Rubaiy HN, Muraki K, Beech DJ, Bon RS. Remarkable Progress with Small-Molecule Modulation of TRPC1/4/5 Channels: Implications for Understanding the Channels in Health and Disease. Cells 2018; 7:E52. [PMID: 29865154 PMCID: PMC6025525 DOI: 10.3390/cells7060052] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/21/2018] [Accepted: 05/23/2018] [Indexed: 12/12/2022] Open
Abstract
Proteins of the TRPC family can form many homo- and heterotetrameric cation channels permeable to Na⁺, K⁺ and Ca2+. In this review, we focus on channels formed by the isoforms TRPC1, TRPC4 and TRPC5. We review evidence for the formation of different TRPC1/4/5 tetramers, give an overview of recently developed small-molecule TRPC1/4/5 activators and inhibitors, highlight examples of biological roles of TRPC1/4/5 channels in different tissues and pathologies, and discuss how high-quality chemical probes of TRPC1/4/5 modulators can be used to understand the involvement of TRPC1/4/5 channels in physiological and pathophysiological processes.
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Affiliation(s)
- Aisling Minard
- School of Chemistry, University of Leeds, Leeds LS2 9JT, UK.
| | - Claudia C Bauer
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
| | - David J Wright
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
| | - Hussein N Rubaiy
- Centre for Atherothrombosis and Metabolic Disease, Hull York Medical School, Hull HU6 7RX, UK.
| | - Katsuhiko Muraki
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, 1-100 Kusumoto, Chikusa, Nagoya 464-8650, Japan.
| | - David J Beech
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
| | - Robin S Bon
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
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5
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Ahmad AA, Streiff M, Hunter C, Hu Q, Sachse FB. Physiological and pathophysiological role of transient receptor potential canonical channels in cardiac myocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017. [PMID: 28629808 DOI: 10.1016/j.pbiomolbio.2017.06.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Transient receptor potential canonical (TRPC) channels constitute a family of seven Ca2+ permeable ion channels, named TRPC1 to 7. These channels are abundantly expressed in the mammalian heart, yet mechanisms underlying activation of TRPC channels and their precise role in cardiac physiology remain poorly understood. In this review, we perused original literature regarding TRPC channels in cardiomyocytes. We first reviewed studies on TRPC channel assembly and sub-cellular localization across multiple species and cell types. Our review indicates that TRPC localization in cardiac cells is still a topic of controversy. We then examined common molecular biology tools used to infer on location and physiological roles of TRPC channels in the heart. We subsequently reviewed pharmacological tools used to modulate TRPC activity in both cardiac and non-cardiac cells. Suggested physiological roles in the heart include modulation of heart rate and sensing of mechanical strain. We examined studies on the contribution of TRPC to cardiac pathophysiology, mainly hypertrophic signaling. Several TRPC channels, particularly TRPC1, 3 and 6 were proposed to play a crucial role in hypertrophic signaling. Finally, we discussed gaps in our understanding of the location and physiological role of TRPC channels in cardiomyocytes. Closing these gaps will be crucial to gain a full understanding of the role of TRPC channels in cardiac pathophysiology and to further explore these channels as targets for treatments for cardiac diseases, in particular, hypertrophy.
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Affiliation(s)
- Azmi A Ahmad
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA; Bioengineering Department, University of Utah, Salt Lake City, USA
| | - Molly Streiff
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA; Bioengineering Department, University of Utah, Salt Lake City, USA
| | - Chris Hunter
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA
| | - Qinghua Hu
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA
| | - Frank B Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA; Bioengineering Department, University of Utah, Salt Lake City, USA.
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6
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Pérez de Vega MJ, Gómez-Monterrey I, Ferrer-Montiel A, González-Muñiz R. Transient Receptor Potential Melastatin 8 Channel (TRPM8) Modulation: Cool Entryway for Treating Pain and Cancer. J Med Chem 2016; 59:10006-10029. [PMID: 27437828 DOI: 10.1021/acs.jmedchem.6b00305] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
TRPM8 ion channels, the primary cold sensors in humans, are activated by innocuous cooling (<28 °C) and cooling compounds (menthol, icilin) and are implicated in sensing unpleasant cold stimuli as well as in mammalian thermoregulation. Overexpression of these thermoregulators in prostate cancer and in other life-threatening tumors, along with their contribution to an increasing number of pathological conditions, opens a plethora of medicinal chemistry opportunities to develop receptor modulators. This Perspective seeks to describe current known modulators for this ion channel because both agonists and antagonists may be useful for the treatment of most TRPM8-mediated pathologies. We primarily focus on SAR data for the different families of compounds and the pharmacological properties of the most promising ligands. Furthermore, we also address the knowledge about the channel structure, although still in its infancy, and the role of the TRPM8 protein signalplex to channel function and dysfunction. We finally outline the potential future prospects of the challenging TRPM8 drug discovery field.
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Affiliation(s)
| | - Isabel Gómez-Monterrey
- Dipartimento di Farmacia, Università "Federico II" de Napoli , Via D. Montesano 49, 80131, Naples, Italy
| | - Antonio Ferrer-Montiel
- Instituto de Biología Molecular y Celular. Universitas Miguel Hernández . 03202 Alicante, Spain
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7
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Hill-Eubanks DC, Gonzales AL, Sonkusare SK, Nelson MT. Vascular TRP channels: performing under pressure and going with the flow. Physiology (Bethesda) 2015; 29:343-60. [PMID: 25180264 DOI: 10.1152/physiol.00009.2014] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endothelial cells and smooth muscle cells of resistance arteries mediate opposing responses to mechanical forces acting on the vasculature, promoting dilation in response to flow and constriction in response to pressure, respectively. In this review, we explore the role of TRP channels, particularly endothelial TRPV4 and smooth muscle TRPC6 and TRPM4 channels, in vascular mechanosensing circuits, placing their putative mechanosensitivity in context with other proposed upstream and downstream signaling pathways.
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Affiliation(s)
| | - Albert L Gonzales
- Department of Pharmacology, University of Vermont, Burlington, Vermont
| | | | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, Vermont
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8
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Maier T, Follmann M, Hessler G, Kleemann HW, Hachtel S, Fuchs B, Weissmann N, Linz W, Schmidt T, Löhn M, Schroeter K, Wang L, Rütten H, Strübing C. Discovery and pharmacological characterization of a novel potent inhibitor of diacylglycerol-sensitive TRPC cation channels. Br J Pharmacol 2015; 172:3650-60. [PMID: 25847402 DOI: 10.1111/bph.13151] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/06/2015] [Accepted: 03/28/2015] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE The cation channel transient receptor potential canonical (TRPC) 6 has been associated with several pathologies including focal segmental glomerulosclerosis, pulmonary hypertension and ischaemia reperfusion-induced lung oedema. We set out to discover novel inhibitors of TRPC6 channels and investigate the therapeutic potential of these agents. EXPERIMENTAL APPROACH A library of potential TRPC channel inhibitors was designed and synthesized. Activity of the compounds was assessed by measuring intracellular Ca(2+) levels. The lead compound SAR7334 was further characterized by whole-cell patch-clamp techniques. The effects of SAR7334 on acute hypoxic pulmonary vasoconstriction (HPV) and systemic BP were investigated. KEY RESULTS SAR7334 inhibited TRPC6, TRPC3 and TRPC7-mediated Ca(2+) influx into cells with IC50 s of 9.5, 282 and 226 nM, whereas TRPC4 and TRPC5-mediated Ca(2+) entry was not affected. Patch-clamp experiments confirmed that the compound blocked TRPC6 currents with an IC50 of 7.9 nM. Furthermore, SAR7334 suppressed TRPC6-dependent acute HPV in isolated perfused lungs from mice. Pharmacokinetic studies of SAR7334 demonstrated that the compound was suitable for chronic oral administration. In an initial short-term study, SAR7334 did not change mean arterial pressure in spontaneously hypertensive rats (SHR). CONCLUSIONS AND IMPLICATIONS Our results confirm the role of TRPC6 channels in hypoxic pulmonary vasoregulation and indicate that these channels are unlikely to play a major role in BP regulation in SHR. SAR7334 is a novel, highly potent and bioavailable inhibitor of TRPC6 channels that opens new opportunities for the investigation of TRPC channel function in vivo.
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Affiliation(s)
- T Maier
- Sanofi R&D, Frankfurt am Main, Germany
| | | | - G Hessler
- Sanofi R&D, Frankfurt am Main, Germany
| | | | - S Hachtel
- Sanofi R&D, Frankfurt am Main, Germany
| | - B Fuchs
- Excellencecluster Cardio-Pulmonary System (ECCPS), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, Giessen, Germany
| | - N Weissmann
- Excellencecluster Cardio-Pulmonary System (ECCPS), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, Giessen, Germany
| | - W Linz
- Sanofi R&D, Frankfurt am Main, Germany
| | - T Schmidt
- Sanofi R&D, Frankfurt am Main, Germany
| | - M Löhn
- Sanofi R&D, Frankfurt am Main, Germany
| | | | - L Wang
- Sanofi R&D, Frankfurt am Main, Germany
| | - H Rütten
- Sanofi R&D, Frankfurt am Main, Germany
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9
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Classical Transient Receptor Potential 1 (TRPC1): Channel or Channel Regulator? Cells 2014; 3:939-62. [PMID: 25268281 PMCID: PMC4276908 DOI: 10.3390/cells3040939] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/07/2014] [Accepted: 09/18/2014] [Indexed: 11/16/2022] Open
Abstract
In contrast to other Classical Transient Receptor Potential TRPC channels the function of TRPC1 as an ion channel is a matter of debate, because it is often difficult to obtain substantial functional signals over background in response to over-expression of TRPC1 alone. Along these lines, heterologously expressed TRPC1 is poorly translocated to the plasma membrane as a homotetramer and may not function on its own physiologically, but may rather be an important linker and regulator protein in heteromeric TRPC channel tetramers. However, due to the lack of specific TRPC1 antibodies able to detect native TRPC1 channels in primary cells, identification of functional TRPC1 containing heteromeric TRPC channel complexes in the plasma membrane is still challenging. Moreover, an extended TRPC1 cDNA, which was recently discovered, may seriously question results obtained in heterologous expression systems transfected with shortened cDNA versions. Therefore, this review will focus on the current status of research on TRPC1 function obtained in primary cells and a TRPC1-deficient mouse model.
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10
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Abstract
The TRPC1 ion channel was the first mammalian TRP channel to be cloned. In humans, it is encoded by the TRPC1 gene located in chromosome 3. The protein is predicted to consist of six transmembrane segments with the N- and C-termini located in the cytoplasm. The extracellular loop connecting transmembrane segments 5 and 6 participates in the formation of the ionic pore region. Inside the cell, TRPC1 is present in the endoplasmic reticulum, plasma membrane, intracellular vesicles, and primary cilium, an antenna-like sensory organelle functioning as a signaling platform. In human and rodent tissues, it shows an almost ubiquitous expression. TRPC1 interacts with a diverse group of proteins including ion channel subunits, receptors, and cytosolic proteins to mediate its effect on Ca(2+) signaling. It primarily functions as a cation nonselective channel within pathways controlling Ca(2+) entry in response to cell surface receptor activation. Through these pathways, it affects basic cell functions, such as proliferation and survival, differentiation, secretion, and cell migration, as well as cell type-specific functions such as chemotropic turning of neuronal growth cones and myoblast fusion. The biological role of TRPC1 has been studied in genetically engineered mice where the Trpc1 gene has been experimentally ablated. Although these mice live to adulthood, they show defects in several organs and tissues, such as the cardiovascular, central nervous, skeletal and muscular, and immune systems. Genetic and functional studies have implicated TRPC1 in diabetic nephropathy, Parkinson's disease, Huntington's disease, Duchenne muscular dystrophy, cancer, seizures, and Darier-White skin disease.
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Affiliation(s)
- Vasyl Nesin
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma City, OK, 73104, USA
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11
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Courjaret R, Hubrack S, Daalis A, Dib M, Machaca K. The
Xenopus
TRPV6 homolog encodes a Mg
2+
‐permeant channel that is inhibited by interaction with TRPC1. J Cell Physiol 2013; 228:2386-98. [DOI: 10.1002/jcp.24411] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/21/2013] [Indexed: 01/29/2023]
Affiliation(s)
- Raphael Courjaret
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Satanay Hubrack
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Arwa Daalis
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Maya Dib
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Khaled Machaca
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
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12
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Ferreira FM, Oliveira LC, Germino GG, Onuchic JN, Onuchic LF. Macromolecular assembly of polycystin-2 intracytosolic C-terminal domain. Proc Natl Acad Sci U S A 2011; 108:9833-8. [PMID: 21622852 PMCID: PMC3116388 DOI: 10.1073/pnas.1106766108] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Mutations in PKD2 are responsible for approximately 15% of the autosomal dominant polycystic kidney disease cases. This gene encodes polycystin-2, a calcium-permeable cation channel whose C-terminal intracytosolic tail (PC2t) plays an important role in its interaction with a number of different proteins. In the present study, we have comprehensively evaluated the macromolecular assembly of PC2t homooligomer using a series of biophysical and biochemical analyses. Our studies, based on a new delimitation of PC2t, have revealed that it is capable of assembling as a homotetramer independently of any other portion of the molecule. Our data support this tetrameric arrangement in the presence and absence of calcium. Molecular dynamics simulations performed with a modified all-atoms structure-based model supported the PC2t tetrameric assembly, as well as how different populations are disposed in solution. The simulations demonstrated, indeed, that the best-scored structures are the ones compatible with a fourfold oligomeric state. These findings clarify the structural properties of PC2t domain and strongly support a homotetramer assembly of PC2.
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Affiliation(s)
- Frederico M. Ferreira
- Division of Nephrology, University of São Paulo School of Medicine, 01246-903, São Paulo, Brazil
- Laboratory of Immunology, Heart Institute, University of São Paulo School of Medicine, 05403-900, São Paulo, Brazil
| | - Leandro C. Oliveira
- Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, CA 92093
| | - Gregory G. Germino
- National Institute of Diabetes, Digestive, and Kidney Diseases, Bethesda, MD 20892-2560
| | - José N. Onuchic
- Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, CA 92093
| | - Luiz F. Onuchic
- Division of Nephrology, University of São Paulo School of Medicine, 01246-903, São Paulo, Brazil
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13
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Kawahara T, Jackson HM, Smith SME, Simpson PD, Lambeth JD. Nox5 forms a functional oligomer mediated by self-association of its dehydrogenase domain. Biochemistry 2011; 50:2013-25. [PMID: 21319793 DOI: 10.1021/bi1020088] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Nox5 belongs to the calcium-regulated subfamily of NADPH oxidases (Nox). Like other calcium-regulated Noxes, Nox5 has an EF-hand-containing calcium-binding domain at its N-terminus, a transmembrane heme-containing region, and a C-terminal dehydrogenase (DH) domain that binds FAD and NADPH. While Nox1-4 require regulatory subunits, including p22phox, Nox5 activity does not depend on any subunits. We found that inactive point mutants and truncated forms of Nox5 (including the naturally expressed splice form, Nox5S) inhibit full-length Nox5, consistent with formation of a dominant negative complex. Oligomerization of full-length Nox5 was demonstrated using co-immunoprecipitation of coexpressed, differentially tagged forms of Nox5 and occurred in a manner independent of calcium ion. Several approaches were used to show that the DH domain mediates oligomerization: Nox5 could be isolated as a multimer when the calcium-binding domain and/or the N-terminal polybasic region (PBR-N) was deleted, but deletion of the DH domain eliminated oligomerization. Further, a chimera containing the transmembrane domain of Ciona intestinalis voltage sensor-containing phosphatase (CiVSP) fused to the Nox5 DH domain formed a co-immunoprecipitating complex with, and functioned as a dominant inhibitor of, full-length Nox5. Radiation inactivation of Nox5 overexpressed in HEK293 cells and endogenously expressed in human aortic smooth muscle cells indicated molecular masses of ∼350 and ∼300 kDa, respectively, consistent with a tetramer being the functionally active unit. Thus, Nox5 forms a catalytically active oligomer in the membrane that is mediated by its dehydrogenase domain. As a result of oligomerization, the short, calcium-independent splice form, Nox5S, may function as an endogenous inhibitor of calcium-stimulated ROS generation by full-length Nox5.
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Affiliation(s)
- Tsukasa Kawahara
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, United States.
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14
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Valenzuela SM, Berkahn M, Porkovich A, Huynh T, Goyette J, Martin DK, Geczy CL. Soluble Structure of CLIC and S100 Proteins Investigated by Atomic Force Microscopy. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/jbnb.2011.21002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Carnally SM, Edwardson JM, Barrera NP. Imaging the spatial orientation of subunits within membrane receptors by atomic force microscopy. Methods Mol Biol 2011; 736:47-60. [PMID: 21660720 DOI: 10.1007/978-1-61779-105-5_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Our experimental approach is based on the atomic force microscope (AFM) imaging of epitope-tagged subunits within membrane protein complexes purified in small amounts and decorated by anti-tag antibodies. Furthermore, we can produce simultaneous decoration of protein complexes using Fab fragments and IgG antibodies, which, combined with chemical modification of the substrate, allows us to determine the protein orientation across the cell membrane. Here, we describe a detailed protocol for membrane protein purification, AFM data collection, analysis, and interpretation of results. The protocol also covers basic AFM instrument settings and best practices for both observation of membrane protein complexes by AFM and automatic detection of the structures by an in-house algorithm. Once a sufficient number of membrane protein complexes have been visualized by AFM, data acquisition and processing can be completed in approximately 10 min using a scanning surface of 1 μm(2).
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Affiliation(s)
- Stewart M Carnally
- Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
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16
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Atomic force microscopy reveals the alternating subunit arrangement of the TRPP2-TRPV4 heterotetramer. Biophys J 2010; 99:790-7. [PMID: 20682256 DOI: 10.1016/j.bpj.2010.05.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Revised: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 12/13/2022] Open
Abstract
There is evidence that polycystin-2 (TRPP2) interacts with two other members of the transient receptor potential (TRP) family, TRPC1 and TRPV4. We have previously shown that TRPP2 forms a heteromeric complex with TRPC1, with a 2:2 stoichiometry and an alternating subunit arrangement. Here, we used coimmunoprecipitation to show that TRPP2 also interacts with TRPV4, but not with TRPA1 or TRPM8; hence, its promiscuity is limited. We then used atomic force microscopy to study the structure of the TRPV4 homomer and the interaction between TRPP2 and TRPV4. The molecular volume of V5-tagged TRPV4 isolated from singly-transfected tsA 201 cells indicated that it assembled as a homotetramer. The distribution of angles between pairs of anti-V5 antibodies bound to TRPV4 particles had a large peak close to 90 degrees and a smaller peak close to 180 degrees , again consistent with the assembly of TRPV4 as a homotetramer. In contrast, the angle distributions for decoration of the TRPP2-TRPV4 heteromer by either anti-Myc or anti-V5 antibodies had major peaks close to 180 degrees. This result indicates that TRPP2-TRPV4 assembles identically to TRPP2-TRPC1, suggesting a common subunit arrangement among heteromeric TRP channels.
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17
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Carnally SM, Johannessen M, Henderson RM, Jackson MB, Edwardson JM. Demonstration of a direct interaction between sigma-1 receptors and acid-sensing ion channels. Biophys J 2010; 98:1182-91. [PMID: 20371317 PMCID: PMC2849097 DOI: 10.1016/j.bpj.2009.12.4293] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 12/08/2009] [Accepted: 12/15/2009] [Indexed: 10/19/2022] Open
Abstract
The sigma-1 receptor is a widely expressed protein that interacts with a variety of ion channels, including the acid-sensing ion channel (ASIC) 1a. Here we used atomic force microscopy to determine the architecture of the ASIC1a/sigma-1 receptor complex. When isolated His(8)-tagged ASIC1a was imaged in complex with anti-His(6) antibodies, the angle between pairs of bound antibodies was 135 degrees , consistent with the known trimeric structure of the channel. When ASIC1a was coexpressed with FLAG/His(6)-tagged sigma-1 receptor, ASIC1a became decorated with small particles, and pairs of these particles bound at an angle of 131 degrees . When these complexes were incubated with anti-FLAG antibodies, pairs of antibodies bound at an angle of 134 degrees , confirming that the small particles were sigma-1 receptors. Of interest, we found that the sigma-1 receptor ligand haloperidol caused an approximately 50% reduction in ASIC1a/sigma-receptor binding, suggesting a way in which sigma-1 ligands might modulate channel properties. For the first time, to our knowledge, we have resolved the structure of a complex between the sigma-1 receptor and a target ion channel, and demonstrated that the stoichiometry of the interaction is 1 sigma-1 receptor/1 ASIC1a subunit.
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Affiliation(s)
- Stewart M. Carnally
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Molly Johannessen
- Department of Physiology, University of Wisconsin, Madison, Wisconsin
| | - Robert M. Henderson
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Meyer B. Jackson
- Department of Physiology, University of Wisconsin, Madison, Wisconsin
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18
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Stewart AP, Egressy K, Lim A, Edwardson JM. AFM imaging reveals the tetrameric structure of the TRPM8 channel. Biochem Biophys Res Commun 2010; 394:383-6. [PMID: 20214891 DOI: 10.1016/j.bbrc.2010.03.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 03/04/2010] [Indexed: 10/19/2022]
Abstract
Several members of the transient receptor potential (TRP) channel superfamily have been shown to assemble as tetramers. Here we have determined the subunit stoichiometry of the transient receptor potential M8 (TRPM8) channel using atomic force microscopy (AFM). TRPM8 channels were isolated from transfected cells, and complexes were formed between the channels and antibodies against a V5 epitope tag present on each subunit. The complexes were then subjected to AFM imaging. A frequency distribution of the molecular volumes of antibody decorated channels had a peak at 1305 nm(3), close to the expected size of a TRPM8 tetramer. The frequency distribution of angles between pairs of bound antibodies had two peaks, at 93 degrees and 172 degrees, confirming that the channel assembles as a tetramer. We suggest that this assembly pattern is common to all members of the TRP channel superfamily.
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Affiliation(s)
- Andrew P Stewart
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB21PD, UK
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19
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Moskalenko AV, Yarova PL, Gordeev SN, Smirnov SV. Single protein molecule mapping with magnetic atomic force microscopy. Biophys J 2010; 98:478-87. [PMID: 20141762 PMCID: PMC2814202 DOI: 10.1016/j.bpj.2009.10.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 10/06/2009] [Accepted: 10/15/2009] [Indexed: 02/04/2023] Open
Abstract
Understanding the structural organization and distribution of proteins in biological cells is of fundamental importance in biomedical research. The use of conventional fluorescent microscopy for this purpose is limited due to its relatively low spatial resolution compared to the size of a single protein molecule. Atomic force microscopy (AFM), on the other hand, allows one to achieve single-protein resolution by scanning the cell surface using a specialized ligand-coated AFM tip. However, because this method relies on short-range interactions, it is limited to the detection of binding sites that are directly accessible to the AFM tip. We developed a method based on magnetic (long-range) interactions and applied it to investigate the structural organization and distribution of endothelin receptors on the surface of smooth muscle cells. Endothelin receptors were labeled with 50-nm superparamagnetic microbeads and then imaged with magnetic AFM. Considering its high spatial resolution and ability to "see" magnetically labeled proteins at a distance of up to 150 nm, this approach may become an important tool for investigating the dynamics of individual proteins both on the cell membrane and in the submembrane space.
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Affiliation(s)
| | - Polina L. Yarova
- Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
| | | | - Sergey V. Smirnov
- Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
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20
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Kobori T, Smith GD, Sandford R, Edwardson JM. The transient receptor potential channels TRPP2 and TRPC1 form a heterotetramer with a 2:2 stoichiometry and an alternating subunit arrangement. J Biol Chem 2010; 284:35507-13. [PMID: 19850920 DOI: 10.1074/jbc.m109.060228] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
There is functional evidence that polycystin-2 (TRPP2) interacts with other members of the transient receptor potential family, including TRPC1 and TRPV4. Here we have used atomic force microscopy to study the structure of the TRPP2 homomer and the interaction between TRPP2 and TRPC1. The molecular volumes of both Myc-tagged TRPP2 and V5-tagged TRPC1 isolated from singly transfected tsA 201 cells indicated that they assembled as homotetramers. The molecular volume of the protein isolated from cells expressing both TRPP2 and TRPC1 was intermediate between the volumes of the two homomers, suggesting that a heteromer was being formed. The distribution of angles between pairs of anti-Myc antibodies bound to TRPP2 particles had a large peak close to 90 degrees and a smaller peak close to 180 degrees , consistent with the assembly of TRPP2 as a homotetramer. In contrast, the corresponding angle distributions for decoration of the TRPP2-TRPC1 heteromer by either anti-Myc or anti-V5 antibodies had predominant peaks close to 180 degrees . This decoration pattern indicates a TRPP2:TRPC1 subunit stoichiometry of 2:2 and an alternating subunit arrangement.
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Affiliation(s)
- Toshiro Kobori
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD
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21
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Inoue R, Jian Z, Kawarabayashi Y. Mechanosensitive TRP channels in cardiovascular pathophysiology. Pharmacol Ther 2009; 123:371-85. [PMID: 19501617 DOI: 10.1016/j.pharmthera.2009.05.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Accepted: 05/14/2009] [Indexed: 12/22/2022]
Abstract
Transient receptor potential (TRP) proteins constitute a large non-voltage-gated cation channel superfamily, activated polymodally by various physicochemical stimuli, and are implicated in a variety of cellular functions. Known activators for TRP include not only chemical stimuli such as receptor stimulation, increased acidity and pungent/cooling agents, but temperature change and various forms of mechanical stimuli such as osmotic stress, membrane stretch, and shear force. Recent investigations have revealed that at least ten mammalian TRPs exhibit mechanosensitivity (TRPC1, 5, 6; TRPV1, 2, 4; TRPM3, 7; TRPA1; TRPP2), but the mechanisms underlying it appear considerably divergent and complex. The proposed mechanisms are associated with lipid bilayer mechanics, specialized force-transducing structures, biochemical reactions, membrane trafficking and transcriptional regulation. Many of mechanosensitive (MS)-TRP channel likely undergo multiple regulations via these mechanisms. In the cardiovascular system in which hemodynamic forces constantly operate, the impact of mechanical stress may be particularly significant. Extensive morphological and functional studies have indicated that several MS-TRP channels are expressed in cardiac muscle, vascular smooth muscle, endothelium and vasosensory neurons, each differentially contributing to cardiovascular (CV) functions. To further complexity, the recent evidence suggests that mechanical stress may synergize with neurohormonal mechanisms thereby amplifying otherwise marginal responses. Furthermore, the currently available data suggest that MS-TRP channels may be involved in CV pathophysiology such as cardiac arrhythmia, cardiac hypertrophy/myopathy, hypertension and aneurysms. This review will overview currently known mechanisms for mechanical activation/modulation of TRPs and possible connections of MS-TRP channels to CV disorders.
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Affiliation(s)
- Ryuji Inoue
- Department of Physiology, Graduate School of Medical Sciences, Fukuoka University, Nanakuma 7-45-1, Jonan-ku, Fukuoka 814-0180, Japan.
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22
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Electromechanical coupling in the membranes of Shaker-transfected HEK cells. Proc Natl Acad Sci U S A 2009; 106:6626-31. [PMID: 19366664 DOI: 10.1073/pnas.0808045106] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Membranes flex with changes in transmembrane potential as a result of changes in interfacial tension, the Lippman effect. We studied the membrane electromotility of Shaker K(+)-transfected HEK-293 cells in real time by using combined patch-clamp atomic force microscopy. In the voltage range where the channels were closed, Shaker expression had little effect on electromotility relative to wild-type cells. Depolarization between -120 and -40 mV resulted in a linear upward cantilever deflection equivalent to an increase in membrane tension. However, when depolarized sufficiently for channel opening, the electromotility saturated and only recovered over 10 s of milliseconds. This remarkable loss of motility was associated with channel opening, not ionic flux or movement of the voltage sensors. The IL mutant of Shaker, in which the voltage dependence of channel opening but not sensor movement is shifted to more positive potentials, caused the loss of electromotility saturation also to shift to more positive potentials. The temporary loss of electromotility associated with channel opening is probably caused by local buckling of the bilayer as the inner half of the channel expands as expected from X-ray structural data.
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23
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Xie H, Guo XM, Chen H. Making the most of fusion tags technology in structural characterization of membrane proteins. Mol Biotechnol 2009; 42:135-45. [PMID: 19199085 DOI: 10.1007/s12033-009-9148-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 01/19/2009] [Indexed: 11/24/2022]
Abstract
Membrane proteins can be investigated at various structural levels, including the topological structure, the high-resolution three-dimensional structure, and the organization and assembly of membrane protein complexes. Gene fusion technology makes it possible to insert a polynucleotide encoding a protein or polypeptide tag into the gene encoding a membrane protein of interest. Resultant recombinant proteins may possess the functions of the original membrane proteins, together with the biochemical properties of the imported fusion tag, greatly enhancing functional and structural studies of membrane proteins. In this article, the latest literature is reviewed in relation to types, applications, strategies, and approaches to fusion tag technology for structural investigations of membrane proteins.
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Affiliation(s)
- Hao Xie
- Department of Biological Science and Biotechnology, Institute of Science, Wuhan University of Technology, People's Republic of China.
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24
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Zhang P, Luo Y, Chasan B, González-Perrett S, Montalbetti N, Timpanaro GA, Cantero MDR, Ramos AJ, Goldmann WH, Zhou J, Cantiello HF. The multimeric structure of polycystin-2 (TRPP2): structural-functional correlates of homo- and hetero-multimers with TRPC1. Hum Mol Genet 2009; 18:1238-51. [PMID: 19193631 DOI: 10.1093/hmg/ddp024] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Polycystin-2 (PC2, TRPP2), the gene product of PKD2, whose mutations cause autosomal dominant polycystic kidney disease (ADPKD), belongs to the superfamily of TRP channels. PC2 is a non-selective cation channel, with multiple subconductance states. In this report, we explored structural and functional properties of PC2 and whether the conductance substates represent monomeric contributions to the channel complex. A kinetic analysis of spontaneous channel currents of PC2 showed that four intrinsic, non-stochastic subconductance states, which followed a staircase behavior, were both pH- and voltage-dependent. To confirm the oligomeric contributions to PC2 channel function, heteromeric PC2/TRPC1 channel complexes were also functionally assessed by single channel current analysis. Low pH inhibited the PC2 currents in PC2 homomeric complexes, but failed to affect PC2 currents in PC2/TRPC1 heteromeric complexes. Amiloride, in contrast, abolished PC2 currents in both the homomeric PC2 complexes and the heteromeric PC2/TRPC1 complexes, thus PC2/TRPC1 complexes have distinct functional properties from the homomeric complexes. The topological features of the homomeric PC2-, TRPC1- and heteromeric PC2/TRPC1 channel complexes, assessed by atomic force microscopy, were consistent with structural tetramers. TRPC1 homomeric channels had different average diameter and protruding height when compared with the PC2 homomers. The contribution of individual monomers to the PC2/TRPC1 hetero-complexes was easily distinguishable. The data support tetrameric models of both the PC2 and TRPC1 channels, where the overall conductance of a particular channel will depend on the contribution of the various functional monomers in the complex.
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Affiliation(s)
- Peng Zhang
- Nephrology Division and Electrophysiology Core, Massachusetts General Hospital East, Charlestown, MA 02129, USA
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25
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Abstract
Transient receptor potential (TRP) channels are important in many neuronal and non-neuronal physiological processes. The past 2 years have seen much progress in the use of structural biology techniques to elucidate molecular mechanisms of TRP channel gating and regulation. Two approaches have proven fruitful: (i) a divide-and-conquer strategy has provided high-resolution structural details of TRP channel fragments although it fails to explain how these fragments are integrated in the full channel; and (ii) electron microscopy of entire TRP channels has yielded low-resolution images that provide a basis for testable models of TRP channel architecture. The results of each approach, summarized in this review, provide a preview of what the future holds in TRP channel structural biology.
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Affiliation(s)
- Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 01238, USA.
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26
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Direct visualization of the trimeric structure of the ASIC1a channel, using AFM imaging. Biochem Biophys Res Commun 2008; 372:752-5. [PMID: 18514062 DOI: 10.1016/j.bbrc.2008.05.100] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2008] [Accepted: 05/20/2008] [Indexed: 01/25/2023]
Abstract
There has been confusion about the subunit stoichiometry of the degenerin family of ion channels. Recently, a crystal structure of acid-sensing ion channel (ASIC) 1a revealed that it assembles as a trimer. Here, we used atomic force microscopy (AFM) to image unprocessed ASIC1a bound to mica. We detected a mixture of subunit monomers, dimers and trimers. In some cases, triple-subunit clusters were clearly visible, confirming the trimeric structure of the channel, and indicating that the trimer sometimes disaggregated after adhesion to the mica surface. This AFM-based technique will now enable us to determine the subunit arrangement within heteromeric ASICs.
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27
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Determination of the architecture of ionotropic receptors using AFM imaging. Pflugers Arch 2007; 456:199-209. [PMID: 18026748 DOI: 10.1007/s00424-007-0381-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 10/26/2007] [Indexed: 10/22/2022]
Abstract
Fast neurotransmission in the nervous system is mediated by ionotropic receptors, all of which contain several subunits surrounding an integral ion channel. There are three major families of ionotropic receptors: the 'Cys-loop' receptors (including the nicotinic receptor for acetylcholine, the 5-HT(3) receptor, the GABA(A) receptor and the glycine receptor), the glutamate receptors (including the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, kainate and N-methyl-D: -aspartic acid receptors) and the P2X receptors for adenosine triphosphate. These receptors are often built from multiple types of subunit, raising the question of the stoichiometry and subunit arrangement within the receptors. This question is of therapeutic significance because in some cases drug-binding sites are located at subunit-subunit interfaces. In this paper, we describe a general method, based on atomic force microscopy imaging, to solve the architecture of multi-subunit proteins, such as the ionotropic receptors. Specific epitope tags are engineered onto each receptor subunit. The subunits are then expressed exogenously in cultured cells, and the receptors are isolated from detergent extracts of membrane fractions by affinity chromatography. The receptors are imaged both alone and in complex with anti-epitope antibodies. The size of the imaged particles provides an estimate of the subunit stoichiometry, whereas the geometry of the receptor-antibody complexes produces more detailed information about the receptor architecture. We use an automated, unbiased system to identify receptors and receptor-antibody complexes and to determine the geometry of the complexes. We are also able to determine the orientation of the receptors on the mica substrate, which will allow us to solve the subunit arrangement within receptors, such as the GABA(A) receptor, which contain three types of subunits.
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