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Role of Monomer/Tetramer Equilibrium of Rod Visual Arrestin in the Interaction with Phosphorylated Rhodopsin. Int J Mol Sci 2023; 24:ijms24054963. [PMID: 36902393 PMCID: PMC10003454 DOI: 10.3390/ijms24054963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 02/25/2023] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
The phototransduction cascade in vertebrate rod visual cells is initiated by the photoactivation of rhodopsin, which enables the activation of the visual G protein transducin. It is terminated by the phosphorylation of rhodopsin, followed by the binding of arrestin. Here we measured the solution X-ray scattering of nanodiscs containing rhodopsin in the presence of rod arrestin to directly observe the formation of the rhodopsin/arrestin complex. Although arrestin self-associates to form a tetramer at physiological concentrations, it was found that arrestin binds to phosphorylated and photoactivated rhodopsin at 1:1 stoichiometry. In contrast, no complex formation was observed for unphosphorylated rhodopsin upon photoactivation, even at physiological arrestin concentrations, suggesting that the constitutive activity of rod arrestin is sufficiently low. UV-visible spectroscopy demonstrated that the rate of the formation of the rhodopsin/arrestin complex well correlates with the concentration of arrestin monomer rather than the tetramer. These findings indicate that arrestin monomer, whose concentration is almost constant due to the equilibrium with the tetramer, binds to phosphorylated rhodopsin. The arrestin tetramer would act as a reservoir of monomer to compensate for the large changes in arrestin concentration in rod cells caused by intense light or adaptation.
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Sander CL, Luu J, Kim K, Furkert D, Jang K, Reichenwallner J, Kang M, Lee HJ, Eger BT, Choe HW, Fiedler D, Ernst OP, Kim YJ, Palczewski K, Kiser PD. Structural evidence for visual arrestin priming via complexation of phosphoinositols. Structure 2022; 30:263-277.e5. [PMID: 34678158 PMCID: PMC8818024 DOI: 10.1016/j.str.2021.10.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/06/2021] [Accepted: 09/29/2021] [Indexed: 02/05/2023]
Abstract
Visual arrestin (Arr1) terminates rhodopsin signaling by blocking its interaction with transducin. To do this, Arr1 translocates from the inner to the outer segment of photoreceptors upon light stimulation. Mounting evidence indicates that inositol phosphates (InsPs) affect Arr1 activity, but the Arr1-InsP molecular interaction remains poorly defined. We report the structure of bovine Arr1 in a ligand-free state featuring a near-complete model of the previously unresolved C-tail, which plays a crucial role in regulating Arr1 activity. InsPs bind to the N-domain basic patch thus displacing the C-tail, suggesting that they prime Arr1 for interaction with rhodopsin and help direct Arr1 translocation. These structures exhibit intact polar cores, suggesting that C-tail removal by InsP binding is insufficient to activate Arr1. These results show how Arr1 activity can be controlled by endogenous InsPs in molecular detail.
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Affiliation(s)
- Christopher L. Sander
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA,Department of Ophthalmology and the Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA
| | - Jennings Luu
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA,Department of Ophthalmology and the Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA
| | - Kyumhyuk Kim
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - David Furkert
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Kiyoung Jang
- Department of Lifestyle Medicine, Jeonbuk National University, Iksan 54596, Republic of Korea
| | | | - MinSoung Kang
- Department of Lifestyle Medicine, Jeonbuk National University, Iksan 54596, Republic of Korea,Thin Film Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Daejeon 34114, Republic of Korea
| | - Ho-Jun Lee
- Department of Ophthalmology and the Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA,Research Service, VA Long Beach Healthcare System, Long Beach, CA 90822, USA
| | - Bryan T. Eger
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Hui-Woog Choe
- Department of Chemistry, Jeonbuk National University, Jeonju 54896, Republic of Korea
| | - Dorothea Fiedler
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Oliver P. Ernst
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Yong Ju Kim
- Department of Lifestyle Medicine, Jeonbuk National University, Iksan 54596, Republic of Korea,Department of Oriental Medicine Resources, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan 54596, Republic of Korea
| | - Krzysztof Palczewski
- Department of Ophthalmology and the Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA,Department of Chemistry and Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA,Department of Physiology & Biophysics, University of California, Irvine, CA 92697, USA
| | - Philip D. Kiser
- Department of Ophthalmology and the Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA,Department of Physiology & Biophysics, University of California, Irvine, CA 92697, USA,Research Service, VA Long Beach Healthcare System, Long Beach, CA 90822, USA,Lead contact
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3
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Ulfig A, Bader V, Varatnitskaya M, Lupilov N, Winklhofer KF, Leichert LI. Hypochlorous acid-modified human serum albumin suppresses MHC class II - dependent antigen presentation in pro-inflammatory macrophages. Redox Biol 2021; 43:101981. [PMID: 33940547 PMCID: PMC8105673 DOI: 10.1016/j.redox.2021.101981] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 12/14/2022] Open
Abstract
Macrophages are innate immune cells that internalize and present exogenous antigens to T cells via MHC class II proteins. They operate at sites of infection in a highly inflammatory environment, generated in part by reactive oxygen species, in particular the strong oxidant hypochlorous acid (HOCl) produced in the neutrophil respiratory burst. HOCl effectively kills a broad range of pathogens but can also contribute to host tissue damage at sites of inflammation. To prevent tissue injury, HOCl is scavenged by human serum albumin (HSA) and other plasma proteins in interstitial fluids, leading to the formation of variously modified advanced oxidation products (AOPPs) with pro-inflammatory properties. Previously, we showed that HOCl-mediated N-chlorination converts HSA and other plasma proteins into efficient activators of the phagocyte respiratory burst, but the role of these AOPPs in antigen presentation by macrophages remained unclear. Here, we show that physiologically relevant amounts of N-chlorinated HSA can strongly impair the capacity of THP-1-derived macrophages to present antigens to antigen-specific T cells via MHC class II proteins at multiple stages. Initially, N-chlorinated HSA inhibits antigen internalization by converting antigens into scavenger receptor (SR) ligands and competing with the modified antigens for binding to SR CD36. Later steps of antigen presentation, such as intracellular antigen processing and MHC class II expression are negatively affected, as well. We propose that impaired processing of pathogens or exogenous antigens by immune cells at an initial stage of infection prevents antigen presentation in an environment potentially hostile to cells of the adaptive immune response, possibly shifting it towards locations removed from the actual insult, like the lymph nodes. On the flip side, excessive retardation or complete inhibition of antigen presentation by N-chlorinated plasma proteins could contribute to chronic infection and inflammation.
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Affiliation(s)
- Agnes Ulfig
- Ruhr University Bochum, Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Verian Bader
- Ruhr University Bochum, Institute of Biochemistry and Pathobiochemistry - Molecular Cell Biology, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Marharyta Varatnitskaya
- Ruhr University Bochum, Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Natalie Lupilov
- Ruhr University Bochum, Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Konstanze F Winklhofer
- Ruhr University Bochum, Institute of Biochemistry and Pathobiochemistry - Molecular Cell Biology, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Lars I Leichert
- Ruhr University Bochum, Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Universitätsstrasse 150, 44780, Bochum, Germany.
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4
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Functional compartmentalization of photoreceptor neurons. Pflugers Arch 2021; 473:1493-1516. [PMID: 33880652 DOI: 10.1007/s00424-021-02558-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 12/16/2022]
Abstract
Retinal photoreceptors are neurons that convert dynamically changing patterns of light into electrical signals that are processed by retinal interneurons and ultimately transmitted to vision centers in the brain. They represent the essential first step in seeing without which the remainder of the visual system is rendered moot. To support this role, the major functions of photoreceptors are segregated into three main specialized compartments-the outer segment, the inner segment, and the pre-synaptic terminal. This compartmentalization is crucial for photoreceptor function-disruption leads to devastating blinding diseases for which therapies remain elusive. In this review, we examine the current understanding of the molecular and physical mechanisms underlying photoreceptor functional compartmentalization and highlight areas where significant knowledge gaps remain.
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Barnes CL, Malhotra H, Calvert PD. Compartmentalization of Photoreceptor Sensory Cilia. Front Cell Dev Biol 2021; 9:636737. [PMID: 33614665 PMCID: PMC7889997 DOI: 10.3389/fcell.2021.636737] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/07/2021] [Indexed: 12/12/2022] Open
Abstract
Functional compartmentalization of cells is a universal strategy for segregating processes that require specific components, undergo regulation by modulating concentrations of those components, or that would be detrimental to other processes. Primary cilia are hair-like organelles that project from the apical plasma membranes of epithelial cells where they serve as exclusive compartments for sensing physical and chemical signals in the environment. As such, molecules involved in signal transduction are enriched within cilia and regulating their ciliary concentrations allows adaptation to the environmental stimuli. The highly efficient organization of primary cilia has been co-opted by major sensory neurons, olfactory cells and the photoreceptor neurons that underlie vision. The mechanisms underlying compartmentalization of cilia are an area of intense current research. Recent findings have revealed similarities and differences in molecular mechanisms of ciliary protein enrichment and its regulation among primary cilia and sensory cilia. Here we discuss the physiological demands on photoreceptors that have driven their evolution into neurons that rely on a highly specialized cilium for signaling changes in light intensity. We explore what is known and what is not known about how that specialization appears to have driven unique mechanisms for photoreceptor protein and membrane compartmentalization.
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Affiliation(s)
| | | | - Peter D. Calvert
- Department of Ophthalmology and Visual Sciences, Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY, United States
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6
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Phosphorylated peptide of G protein-coupled receptor induces dimerization in activated arrestin. Sci Rep 2020; 10:10938. [PMID: 32616825 PMCID: PMC7331637 DOI: 10.1038/s41598-020-67944-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 06/16/2020] [Indexed: 11/08/2022] Open
Abstract
Termination of the G-protein-coupled receptor signaling involves phosphorylation of its C-terminus and subsequent binding of the regulatory protein arrestin. In the visual system, arrestin-1 preferentially binds to photoactivated and phosphorylated rhodopsin and inactivates phototransduction. Here, we have investigated binding of a synthetic phosphopeptide of bovine rhodopsin (residues 323-348) to the active variants of visual arrestin-1: splice variant p44, and the mutant R175E. Unlike the wild type arrestin-1, both these arrestins are monomeric in solution. Solution structure analysis using small angle X-ray scattering supported by size exclusion chromatography results reveal dimerization in both the arrestins in the presence of phosphopeptide. Our results are the first report, to our knowledge, on receptor-induced oligomerization in arrestin, suggesting possible roles for the cellular function of arrestin oligomers. Given high structural homology and the similarities in their activation mechanism, these results are expected to have implications for all arrestin isoforms.
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Haider RS, Wilhelm F, Rizk A, Mutt E, Deupi X, Peterhans C, Mühle J, Berger P, Schertler GFX, Standfuss J, Ostermaier MK. Arrestin-1 engineering facilitates complex stabilization with native rhodopsin. Sci Rep 2019; 9:439. [PMID: 30679635 PMCID: PMC6346018 DOI: 10.1038/s41598-018-36881-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 11/23/2018] [Indexed: 01/14/2023] Open
Abstract
Arrestin-1 desensitizes the activated and phosphorylated photoreceptor rhodopsin by forming transient rhodopsin−arrestin-1 complexes that eventually decay to opsin, retinal and arrestin-1. Via a multi-dimensional screening setup, we identified and combined arrestin-1 mutants that form lasting complexes with light-activated and phosphorylated rhodopsin in harsh conditions, such as high ionic salt concentration. Two quadruple mutants, D303A + T304A + E341A + F375A and R171A + T304A + E341A + F375A share similar heterologous expression and thermo-stability levels with wild type (WT) arrestin-1, but are able to stabilize complexes with rhodopsin with more than seven times higher half-maximal inhibitory concentration (IC50) values for NaCl compared to the WT arrestin-1 protein. These quadruple mutants are also characterized by higher binding affinities to phosphorylated rhodopsin, light-activated rhodopsin and phosphorylated opsin, as compared with WT arrestin-1. Furthermore, the assessed arrestin-1 mutants are still specifically associating with phosphorylated or light-activated receptor states only, while binding to the inactive ground state of the receptor is not significantly altered. Additionally, we propose a novel functionality for R171 in stabilizing the inactive arrestin-1 conformation as well as the rhodopsin–arrestin-1 complex. The achieved stabilization of the active rhodopsin–arrestin-1 complex might be of great interest for future structure determination, antibody development studies as well as drug-screening efforts targeting G protein-coupled receptors (GPCRs).
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Affiliation(s)
- Raphael S Haider
- InterAx Biotech AG, PARK InnovAARE, Villigen, 5234, Switzerland.,Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland.,Institute of Molecular Cell Biology, Jena, 07745, Germany
| | - Florian Wilhelm
- InterAx Biotech AG, PARK InnovAARE, Villigen, 5234, Switzerland
| | - Aurélien Rizk
- InterAx Biotech AG, PARK InnovAARE, Villigen, 5234, Switzerland
| | - Eshita Mutt
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Xavier Deupi
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Christian Peterhans
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Jonas Mühle
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Philipp Berger
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Gebhard F X Schertler
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland.,ETH Zurich, Zurich, 8093, Switzerland
| | - Jörg Standfuss
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
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Deming JD, Pak JS, Shin JA, Brown BM, Kim MK, Aung MH, Lee EJ, Pardue MT, Craft CM. Arrestin 1 and Cone Arrestin 4 Have Unique Roles in Visual Function in an All-Cone Mouse Retina. Invest Ophthalmol Vis Sci 2016; 56:7618-28. [PMID: 26624493 DOI: 10.1167/iovs.15-17832] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Previous studies discovered cone phototransduction shutoff occurs normally for Arr1-/- and Arr4-/-; however, it is defective when both visual arrestins are simultaneously not expressed (Arr1-/-Arr4-/-). We investigated the roles of visual arrestins in an all-cone retina (Nrl-/-) since each arrestin has differential effects on visual function, including ARR1 for normal light adaptation, and ARR4 for normal contrast sensitivity and visual acuity. METHODS We examined Nrl-/-, Nrl-/-Arr1-/-, Nrl-/-Arr4-/-, and Nrl-/-Arr1-/-Arr4-/- mice with photopic electroretinography (ERG) to assess light adaptation and retinal responses, immunoblot and immunohistochemical localization analysis to measure retinal expression levels of M- and S-opsin, and optokinetic tracking (OKT) to measure the visual acuity and contrast sensitivity. RESULTS Study results indicated that Nrl-/- and Nrl-/-Arr4-/- mice light adapted normally, while Nrl-/-Arr1-/- and Nrl-/-Arr1-/-Arr4-/- mice did not. Photopic ERG a-wave, b-wave, and flicker amplitudes followed a general pattern in which Nrl-/-Arr4-/- amplitudes were higher than the amplitudes of Nrl-/-, while the amplitudes of Nrl-/-Arr1-/- and Nrl-/-Arr1-/-Arr4-/- were lower. All three visual arrestin knockouts had faster implicit times than Nrl-/- mice. M-opsin expression is lower when ARR1 is not expressed, while S-opsin expression is lower when ARR4 is not expressed. Although M-opsin expression is mislocalized throughout the photoreceptor cells, S-opsin is confined to the outer segments in all genotypes. Contrast sensitivity is decreased when ARR4 is not expressed, while visual acuity was normal except in Nrl-/-Arr1-/-Arr4-/-. CONCLUSIONS Based on the opposite visual phenotypes in an all-cone retina in the Nrl-/-Arr1-/- and Nrl-/-Arr4-/- mice, we conclude that ARR1 and ARR4 perform unique modulatory roles in cone photoreceptors.
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Affiliation(s)
- Janise D Deming
- Mary D. Allen Laboratory for Vision Research, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, USC Eye Institute, Los Angeles, California, United States
| | - Joseph S Pak
- Mary D. Allen Laboratory for Vision Research, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, USC Eye Institute, Los Angeles, California, United States
| | - Jung-A Shin
- Mary D. Allen Laboratory for Vision Research, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, USC Eye Institute, Los Angeles, California, United States 2Department of Anatomy, School of Medicine, Ewha Womans
| | - Bruce M Brown
- Mary D. Allen Laboratory for Vision Research, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, USC Eye Institute, Los Angeles, California, United States
| | - Moon K Kim
- Rehabilitation Research & Development Center of Excellence, Atlanta VA Medical Center, Decatur, Georgia, United States
| | - Moe H Aung
- Neuroscience/Ophthalmology, Emory University, Atlanta, Georgia, United States
| | - Eun-Jin Lee
- Mary D. Allen Laboratory for Vision Research, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, USC Eye Institute, Los Angeles, California, United States 5Department of Biomedical Engineering, University of Sou
| | - Machelle T Pardue
- Rehabilitation Research & Development Center of Excellence, Atlanta VA Medical Center, Decatur, Georgia, United States 4Neuroscience/Ophthalmology, Emory University, Atlanta, Georgia, United States
| | - Cheryl Mae Craft
- Mary D. Allen Laboratory for Vision Research, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, USC Eye Institute, Los Angeles, California, United States 6Department of Cell & Neurobiology, Keck School of Medic
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Ostermaier MK, Schertler GFX, Standfuss J. Molecular mechanism of phosphorylation-dependent arrestin activation. Curr Opin Struct Biol 2014; 29:143-51. [PMID: 25484000 DOI: 10.1016/j.sbi.2014.07.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/16/2014] [Accepted: 07/18/2014] [Indexed: 12/31/2022]
Abstract
The past years have seen tremendous progress towards understanding how arrestins recognize phosphorylated G protein-coupled receptors (GPCRs). Two arrestin crystal structures, one of a pre-activated splice variant and one bound to a GPCR phosphopeptide, provided insights into the conformational changes upon phosphate recognition. Scanning mutagenesis and spectroscopic studies complete the picture of arrestin activation and receptor binding. Most perspicuous is the C-tail exchange mechanism, by which the C-tail of arrestin is released from its basal conformation and replaced by the phosphorylated GPCR C-terminus. Three positively charged clusters could act as conserved arrestin phosphosensors. Variations in the pattern of phosphorylation in a GPCR and variations within the C-terminus of different GPCRs may encode specificity to arrestin subtypes and particular physiological responses.
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Affiliation(s)
- Martin K Ostermaier
- Laboratory of Biomolecular Research, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Gebhard F X Schertler
- Laboratory of Biomolecular Research, Paul Scherrer Institute, 5232 Villigen, Switzerland; Deparment of Biology, ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zürich, Switzerland
| | - Joerg Standfuss
- Laboratory of Biomolecular Research, Paul Scherrer Institute, 5232 Villigen, Switzerland.
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Abstract
Programmed cell death (apoptosis) is a coordinated set of events eventually leading to the massive activation of specialized proteases (caspases) that cleave numerous substrates, orchestrating fairly uniform biochemical changes than culminate in cellular suicide. Apoptosis can be triggered by a variety of stimuli, from external signals or growth factor withdrawal to intracellular conditions, such as DNA damage or ER stress. Arrestins regulate many signaling cascades involved in life-or-death decisions in the cell, so it is hardly surprising that numerous reports document the effects of ubiquitous nonvisual arrestins on apoptosis under various conditions. Although these findings hardly constitute a coherent picture, with the same arrestin subtypes, sometimes via the same signaling pathways, reported to promote or inhibit cell death, this might reflect real differences in pro- and antiapoptotic signaling in different cells under a variety of conditions. Recent finding suggests that one of the nonvisual subtypes, arrestin-2, is specifically cleaved by caspases. Generated fragment actively participates in the core mechanism of apoptosis: it assists another product of caspase activity, tBID, in releasing cytochrome C from mitochondria. This is the point of no return in committing vertebrate cells to death, and the aspartate where caspases cleave arrestin-2 is evolutionary conserved in vertebrate, but not in invertebrate arrestins. In contrast to wild-type arrestin-2, its caspase-resistant mutant does not facilitate cell death.
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Affiliation(s)
- Seunghyi Kook
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Ave, Nashville, TN, 37232, USA
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Abstract
Arrestin-1 is the second most abundant protein in rod photoreceptors and is nearly equimolar to rhodopsin. Its well-recognized role is to "arrest" signaling from light-activated, phosphorylated rhodopsin, a prototypical G protein-coupled receptor. In doing so, arrestin-1 plays a key role in the rapid recovery of the light response. Arrestin-1 exists in a basal conformation that is stabilized by two independent sets of intramolecular interactions. The intramolecular constraints are disrupted by encountering (1) active conformation of the receptor (R*) and (2) receptor-attached phosphates. Requirement for these two events ensures its highly specific high-affinity binding to phosphorylated, light-activated rhodopsin (P-R*). In the dark-adapted state, the basal form is further organized into dimers and tetramers. Emerging data suggest pleiotropic roles of arrestin-1 beyond the functional range of rod cells. These include light-induced arrestin-1 translocation from the inner segment to the outer segment, a process that may be protective against cellular damage incurred by constitutive signaling. Its expanding list of binding partners also hints at additional, yet to be characterized functions. Uncovering these novel roles of arrestin-1 is a subject of future studies.
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12
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Chen Q, Zhuo Y, Kim M, Hanson SM, Francis DJ, Vishnivetskiy SA, Altenbach C, Klug CS, Hubbell WL, Gurevich VV. Self-association of arrestin family members. Handb Exp Pharmacol 2014; 219:205-23. [PMID: 24292832 DOI: 10.1007/978-3-642-41199-1_11] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mammals express four arrestin subtypes, three of which have been shown to self-associate. Cone photoreceptor-specific arrestin-4 is the only one that is a constitutive monomer. Visual arrestin-1 forms tetramers both in crystal and in solution, but the shape of its physiologically relevant solution tetramer is very different from that in the crystal. The biological role of the self-association of arrestin-1, expressed at very high levels in rod and cone photoreceptors, appears to be protective, reducing the concentration of cytotoxic monomers. The two nonvisual arrestin subtypes are highly homologous, and self-association of both is facilitated by IP6, yet they form dramatically different oligomers. Arrestin-2 apparently self-associates into "infinite" chains, very similar to those observed in IP6-soaked crystals, where IP6 connects the concave sides of the N- and C-domains of adjacent protomers. In contrast, arrestin-3 only forms dimers, in which IP6 likely connects the C-domains of two arrestin-3 molecules. Thus, each of the three self-associating arrestins does it in its own way, forming three different types of oligomers. The physiological role of the oligomerization of arrestin-1 and both nonvisual arrestins might be quite different, and in each case it remains to be definitively elucidated.
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Affiliation(s)
- Qiuyan Chen
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, Nashville, TN, 37232, USA
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13
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Song X, Seo J, Baameur F, Vishnivetskiy SA, Chen Q, Kook S, Kim M, Brooks EK, Altenbach C, Hong Y, Hanson SM, Palazzo MC, Chen J, Hubbell WL, Gurevich EV, Gurevich VV. Rapid degeneration of rod photoreceptors expressing self-association-deficient arrestin-1 mutant. Cell Signal 2013; 25:2613-24. [PMID: 24012956 DOI: 10.1016/j.cellsig.2013.08.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 08/23/2013] [Indexed: 10/26/2022]
Abstract
Arrestin-1 binds light-activated phosphorhodopsin and ensures timely signal shutoff. We show that high transgenic expression of an arrestin-1 mutant with enhanced rhodopsin binding and impaired oligomerization causes apoptotic rod death in mice. Dark rearing does not prevent mutant-induced cell death, ruling out the role of arrestin complexes with light-activated rhodopsin. Similar expression of WT arrestin-1 that robustly oligomerizes, which leads to only modest increase in the monomer concentration, does not affect rod survival. Moreover, WT arrestin-1 co-expressed with the mutant delays retinal degeneration. Thus, arrestin-1 mutant directly affects cell survival via binding partner(s) other than light-activated rhodopsin. Due to impaired self-association of the mutant its high expression dramatically increases the concentration of the monomer. The data suggest that monomeric arrestin-1 is cytotoxic and WT arrestin-1 protects rods by forming mixed oligomers with the mutant and/or competing with it for the binding to non-receptor partners. Thus, arrestin-1 self-association likely serves to keep low concentration of the toxic monomer. The reduction of the concentration of harmful monomer is an earlier unappreciated biological function of protein oligomerization.
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Affiliation(s)
- Xiufeng Song
- Vanderbilt University, Nashville, TN 37232, United States
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Pearring JN, Salinas RY, Baker SA, Arshavsky VY. Protein sorting, targeting and trafficking in photoreceptor cells. Prog Retin Eye Res 2013; 36:24-51. [PMID: 23562855 DOI: 10.1016/j.preteyeres.2013.03.002] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/22/2013] [Accepted: 03/26/2013] [Indexed: 01/24/2023]
Abstract
Vision is the most fundamental of our senses initiated when photons are absorbed by the rod and cone photoreceptor neurons of the retina. At the distal end of each photoreceptor resides a light-sensing organelle, called the outer segment, which is a modified primary cilium highly enriched with proteins involved in visual signal transduction. At the proximal end, each photoreceptor has a synaptic terminal, which connects this cell to the downstream neurons for further processing of the visual information. Understanding the mechanisms involved in creating and maintaining functional compartmentalization of photoreceptor cells remains among the most fascinating topics in ocular cell biology. This review will discuss how photoreceptor compartmentalization is supported by protein sorting, targeting and trafficking, with an emphasis on the best-studied cases of outer segment-resident proteins.
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Affiliation(s)
- Jillian N Pearring
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
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15
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Vishnivetskiy SA, Baameur F, Findley KR, Gurevich VV. Critical role of the central 139-loop in stability and binding selectivity of arrestin-1. J Biol Chem 2013; 288:11741-50. [PMID: 23476014 DOI: 10.1074/jbc.m113.450031] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arrestin-1 selectively binds active phosphorylated rhodopsin (P-Rh*), demonstrating much lower affinity for inactive phosphorylated (P-Rh) and unphosphorylated active (Rh*) forms. Receptor interaction induces significant conformational changes in arrestin-1, which include large movement of the previously neglected 139-loop in the center of the receptor binding surface, away from the incoming receptor. To elucidate the functional role of this loop, in mouse arrestin-1 we introduced deletions of variable lengths and made several substitutions of Lys-142 in it and Asp-72 in the adjacent loop. Several mutants with perturbations in the 139-loop demonstrate increased binding to P-Rh*, dark P-Rh, Rh*, and phospho-opsin. Enhanced binding of arrestin-1 mutants to non-preferred forms of rhodopsin correlates with decreased thermal stability. The 139-loop perturbations increase P-Rh* binding of arrestin-1 at low temperatures and further change its binding profile on the background of 3A mutant, where the C-tail is detached from the body of the molecule by triple alanine substitution. Thus, the 139-loop stabilizes basal conformation of arrestin-1 and acts as a brake, preventing its binding to non-preferred forms of rhodopsin. Conservation of this loop in other subtypes suggests that it has the same function in all members of the arrestin family.
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16
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Smith WC. The role of arrestins in visual and disease processes of the eye. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:243-65. [PMID: 23764057 DOI: 10.1016/b978-0-12-394440-5.00010-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Visual arrestins are well known for their function in quenching the phototransduction process in rods and cones. Perhaps not as well known is their participation in multiple other processes in the normal and disease states of the eye. This chapter covers the range of the known functions of the visual arrestins, beginning with their classical role in quenching light-activated visual pigments. The role of visual arrestins is also reviewed from the perspective of their dynamic mobility whereby they redistribute significantly between the compartments of highly polarized photoreceptor cells. Additional roles of the visual arrestins are also reviewed based on new interacting partners that have been discovered over the past decade. Finally, the contribution of the visual arrestins to diseases of the visual system is explored.
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Affiliation(s)
- W Clay Smith
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
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17
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Gurevich VV, Gurevich EV. Structural determinants of arrestin functions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:57-92. [PMID: 23764050 PMCID: PMC4514030 DOI: 10.1016/b978-0-12-394440-5.00003-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Arrestins are a small protein family with only four members in mammals. Arrestins demonstrate an amazing versatility, interacting with hundreds of different G protein-coupled receptor (GPCR) subtypes, numerous nonreceptor signaling proteins, and components of the internalization machinery, as well as cytoskeletal elements, including regular microtubules and centrosomes. Here, we focus on the structural determinants that mediate various arrestin functions. The receptor-binding elements in arrestins were mapped fairly comprehensively, which set the stage for the construction of mutants targeting particular GPCRs. The elements engaged by other binding partners are only now being elucidated and in most cases we have more questions than answers. Interestingly, even very limited and imprecise identification of structural requirements for the interaction with very few other proteins has enabled the development of signaling-biased arrestin mutants. More comprehensive understanding of the structural underpinning of different arrestin functions will pave the way for the construction of arrestins that can link the receptor we want to the signaling pathway of our choosing.
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Affiliation(s)
- Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
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18
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Involvement of distinct arrestin-1 elements in binding to different functional forms of rhodopsin. Proc Natl Acad Sci U S A 2012; 110:942-7. [PMID: 23277586 DOI: 10.1073/pnas.1215176110] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Solution NMR spectroscopy of labeled arrestin-1 was used to explore its interactions with dark-state phosphorylated rhodopsin (P-Rh), phosphorylated opsin (P-opsin), unphosphorylated light-activated rhodopsin (Rh*), and phosphorylated light-activated rhodopsin (P-Rh*). Distinct sets of arrestin-1 elements were seen to be engaged by Rh* and inactive P-Rh, which induced conformational changes that differed from those triggered by binding of P-Rh*. Although arrestin-1 affinity for Rh* was seen to be low (K(D) > 150 μM), its affinity for P-Rh (K(D) ~80 μM) was comparable to the concentration of active monomeric arrestin-1 in the outer segment, suggesting that P-Rh generated by high-gain phosphorylation is occupied by arrestin-1 under physiological conditions and will not signal upon photo-activation. Arrestin-1 was seen to bind P-Rh* and P-opsin with fairly high affinity (K(D) of~50 and 800 nM, respectively), implying that arrestin-1 dissociation is triggered only upon P-opsin regeneration with 11-cis-retinal, precluding noise generated by opsin activity. Based on their observed affinity for arrestin-1, P-opsin and inactive P-Rh very likely affect the physiological monomer-dimer-tetramer equilibrium of arrestin-1, and should therefore be taken into account when modeling photoreceptor function. The data also suggested that complex formation with either P-Rh* or P-opsin results in a global transition in the conformation of arrestin-1, possibly to a dynamic molten globule-like structure. We hypothesize that this transition contributes to the mechanism that triggers preferential interactions of several signaling proteins with receptor-activated arrestins.
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19
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Vishnivetskiy SA, Chen Q, Palazzo MC, Brooks EK, Altenbach C, Iverson TM, Hubbell WL, Gurevich VV. Engineering visual arrestin-1 with special functional characteristics. J Biol Chem 2012; 288:3394-405. [PMID: 23250748 DOI: 10.1074/jbc.m112.445437] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Arrestin-1 preferentially binds active phosphorylated rhodopsin. Previously, a mutant with enhanced binding to unphosphorylated active rhodopsin (Rh*) was shown to partially compensate for lack of rhodopsin phosphorylation in vivo. Here we showed that reengineering of the receptor binding surface of arrestin-1 further improves the binding to Rh* while preserving protein stability. In mammals, arrestin-1 readily self-associates at physiological concentrations. The biological role of this phenomenon can only be elucidated by replacing wild type arrestin-1 in living animals with a non-oligomerizing mutant retaining all other functions. We demonstrate that constitutively monomeric forms of arrestin-1 are sufficiently stable for in vivo expression. We also tested the idea that individual functions of arrestin-1 can be independently manipulated to generate mutants with the desired combinations of functional characteristics. Here we showed that this approach is feasible; stable forms of arrestin-1 with high Rh* binding can be generated with or without the ability to self-associate. These novel molecular tools open the possibility of testing of the biological role of arrestin-1 self-association and pave the way to elucidation of full potential of compensational approach to gene therapy of gain-of-function receptor mutations.
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20
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Najafi M, Calvert PD. Transport and localization of signaling proteins in ciliated cells. Vision Res 2012; 75:11-8. [PMID: 22922002 DOI: 10.1016/j.visres.2012.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/05/2012] [Accepted: 08/08/2012] [Indexed: 11/16/2022]
Abstract
Most cells in the human body elaborate cilia which serve a wide variety of functions, including cell and tissue differentiation during development, sensing physical and chemical properties of the extracellular milieu and mechanical force generation. Common among cilia is the transduction of external stimuli into signals that regulate the activities of the cilia and the cells that possess them. These functions require the transport and localization of specialized proteins to the cilium, a process that many recent studies have shown to be vital for normal cell function and, ultimately, the health of the organism. Here we discuss several mechanisms proposed for the transport and localization of soluble and peripheral membrane proteins to, or their exclusion from the ciliary compartment with a focus on how the structure of the cytoplasm and the size and shape of proteins influence these processes. Additionally, we examine the impact of cell and protein structure on our ability to accurately measure the relative concentrations of fluorescently tagged proteins amongst various cellular domains, which is integral to our understanding of the molecular mechanisms underlying protein localization and transport.
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Affiliation(s)
- Mehdi Najafi
- Department of Ophthalmology and the Center for Vision Research, SUNY Upstate Medical University, United States
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21
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Yanamala N, Gardner E, Riciutti A, Klein-Seetharaman J. The cytoplasmic rhodopsin-protein interface: potential for drug discovery. Curr Drug Targets 2012; 13:3-14. [PMID: 21777183 PMCID: PMC3275648 DOI: 10.2174/138945012798868461] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2010] [Revised: 02/08/2011] [Accepted: 02/10/2011] [Indexed: 01/20/2023]
Abstract
The mammalian dim-light photoreceptor rhodopsin is a prototypic G protein coupled receptor (GPCR), interacting with the G protein, transducin, rhodopsin kinase, and arrestin. All of these proteins interact with rhodopsin at its cytoplasmic surface. Structural and modeling studies have provided in-depth descriptions of the respective interfaces. Overlap and thus competition for binding surfaces is a major regulatory mechanism for signal processing. Recently, it was found that the same surface is also targeted by small molecules. These ligands can directly interfere with the binding and activation of the proteins of the signal transduction cascade, but they can also allosterically modulate the retinal ligand binding pocket. Because the pocket that is targeted contains residues that are highly conserved across Class A GPCRs, these findings imply that it may be possible to target multiple GPCRs with the same ligand(s). This is desirable for example in complex diseases such as cancer where multiple GPCRs participate in the disease networks.
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Affiliation(s)
- Naveena Yanamala
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Eric Gardner
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Alec Riciutti
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Judith Klein-Seetharaman
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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22
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Steric volume exclusion sets soluble protein concentrations in photoreceptor sensory cilia. Proc Natl Acad Sci U S A 2011; 109:203-8. [PMID: 22184246 DOI: 10.1073/pnas.1115109109] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Proteins segregate into discrete subcellular compartments via a variety of mechanisms, including motor protein transport, local binding, and diffusion barriers. This physical separation of cell functions serves, in part, as a mechanism for controlling compartment activity by allowing regulation of local protein concentrations. In this study we explored how soluble protein size impacts access to the confined space within the retinal photoreceptor outer segment signaling compartment and discovered a strikingly steep relationship. We find that GFP monomers, dimers, and trimers expressed transgenically in frog rods are present in the outer segment at 1.8-, 2.9-, and 6.8-fold lower abundances, relative to the cell body, than the small soluble fluorescent marker, calcein. Theoretical analysis, based on statistical-mechanical models of molecular access to polymer meshes, shows that these observations can be explained by the steric hindrance of molecules occupying the highly constrained spaces between outer segment disc membranes. This mechanism may answer a long-standing question of how the soluble regulatory protein, arrestin, is effectively excluded from the outer segments of dark-adapted rods and cones. Generally, our results suggest an alternate mode for the control of protein access to cell domains based on dynamic, size-dependent compartmental partitioning that does not require diffusion barriers, active transport, or large numbers of immobile binding sites.
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23
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Nielsen JW, Jensen KS, Hansen RE, Gotfredsen CH, Winther JR. A fluorescent probe which allows highly specific thiol labeling at low pH. Anal Biochem 2011; 421:115-20. [PMID: 22178918 DOI: 10.1016/j.ab.2011.11.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
Abstract
Determination of the thiol-disulfide status in biological systems is challenging as redox pools are easily perturbed during sample preparation. This is particularly pertinent under neutral to mildly alkaline conditions typically required for alkylation of thiols. Here we describe the synthesis and properties of a thiol-specific reagent, fluorescent cyclic activated disulfide (FCAD), which includes the fluorescein moiety as fluorophore and utilizes a variation of thiol-disulfide exchange chemistry. The leaving-group character of FCAD makes it reactive at pH 3, allowing modification at low pH, limiting thiol-disulfide exchange. Different applications are demonstrated including picomolar thiol detection, determination of redox potentials, and in-gel detection of labeled proteins.
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Affiliation(s)
- Jonas W Nielsen
- Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
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24
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Gurevich VV, Hanson SM, Song X, Vishnivetskiy SA, Gurevich EV. The functional cycle of visual arrestins in photoreceptor cells. Prog Retin Eye Res 2011; 30:405-30. [PMID: 21824527 DOI: 10.1016/j.preteyeres.2011.07.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 07/20/2011] [Accepted: 07/21/2011] [Indexed: 01/14/2023]
Abstract
Visual arrestin-1 plays a key role in the rapid and reproducible shutoff of rhodopsin signaling. Its highly selective binding to light-activated phosphorylated rhodopsin is an integral part of the functional perfection of rod photoreceptors. Structure-function studies revealed key elements of the sophisticated molecular mechanism ensuring arrestin-1 selectivity and paved the way to the targeted manipulation of the arrestin-1 molecule to design mutants that can compensate for congenital defects in rhodopsin phosphorylation. Arrestin-1 self-association and light-dependent translocation in photoreceptor cells work together to keep a constant supply of active rhodopsin-binding arrestin-1 monomer in the outer segment. Recent discoveries of arrestin-1 interaction with other signaling proteins suggest that it is a much more versatile signaling regulator than previously thought, affecting the function of the synaptic terminals and rod survival. Elucidation of the fine molecular mechanisms of arrestin-1 interactions with rhodopsin and other binding partners is necessary for the comprehensive understanding of rod function and for devising novel molecular tools and therapeutic approaches to the treatment of visual disorders.
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Affiliation(s)
- Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Ave, PRB, Rm 417D, Nashville, TN 37232, USA.
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25
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Cleghorn WM, Tsakem EL, Song X, Vishnivetskiy SA, Seo J, Chen J, Gurevich EV, Gurevich VV. Progressive reduction of its expression in rods reveals two pools of arrestin-1 in the outer segment with different roles in photoresponse recovery. PLoS One 2011; 6:e22797. [PMID: 21818392 PMCID: PMC3144249 DOI: 10.1371/journal.pone.0022797] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 07/02/2011] [Indexed: 01/10/2023] Open
Abstract
Light-induced rhodopsin signaling is turned off with sub-second kinetics by rhodopsin phosphorylation followed by arrestin-1 binding. To test the availability of the arrestin-1 pool in dark-adapted outer segment (OS) for rhodopsin shutoff, we measured photoresponse recovery rates of mice with arrestin-1 content in the OS of 2.5%, 5%, 60%, and 100% of wild type (WT) level by two-flash ERG with the first (desensitizing) flash at 160, 400, 1000, and 2500 photons/rod. The time of half recovery (thalf) in WT retinas increases with the intensity of the initial flash, becoming ∼2.5-fold longer upon activation of 2500 than after 160 rhodopsins/rod. Mice with 60% and even 5% of WT arrestin-1 level recovered at WT rates. In contrast, the mice with 2.5% of WT arrestin-1 had a dramatically slower recovery than the other three lines, with the thalf increasing ∼28 fold between 160 and 2500 rhodopsins/rod. Even after the dimmest flash, the rate of recovery of rods with 2.5% of normal arrestin-1 was two times slower than in other lines, indicating that arrestin-1 level in the OS between 100% and 5% of WT is sufficient for rapid recovery, whereas with lower arrestin-1 the rate of recovery dramatically decreases with increased light intensity. Thus, the OS has two distinct pools of arrestin-1: cytoplasmic and a separate pool comprising ∼2.5% that is not immediately available for rhodopsin quenching. The observed delay suggests that this pool is localized at the periphery, so that its diffusion across the OS rate-limits the recovery. The line with very low arrestin-1 expression is the first where rhodopsin inactivation was made rate-limiting by arrestin manipulation.
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Affiliation(s)
- Whitney M. Cleghorn
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Elviche L. Tsakem
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Xiufeng Song
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sergey A. Vishnivetskiy
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Jungwon Seo
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Jeannie Chen
- Department of Cell and Neurobiology, University of Southern California, Los Angeles, California, United States of America
| | - Eugenia V. Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Vsevolod V. Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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26
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Vishnivetskiy SA, Gimenez LE, Francis DJ, Hanson SM, Hubbell WL, Klug CS, Gurevich VV. Few residues within an extensive binding interface drive receptor interaction and determine the specificity of arrestin proteins. J Biol Chem 2011; 286:24288-99. [PMID: 21471193 DOI: 10.1074/jbc.m110.213835] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Arrestins bind active phosphorylated forms of G protein-coupled receptors, terminating G protein activation, orchestrating receptor trafficking, and redirecting signaling to alternative pathways. Visual arrestin-1 preferentially binds rhodopsin, whereas the two non-visual arrestins interact with hundreds of G protein-coupled receptor subtypes. Here we show that an extensive surface on the concave side of both arrestin-2 domains is involved in receptor binding. We also identified a small number of residues on the receptor binding surface of the N- and C-domains that largely determine the receptor specificity of arrestins. We show that alanine substitution of these residues blocks the binding of arrestin-1 to rhodopsin in vitro and of arrestin-2 and -3 to β2-adrenergic, M2 muscarinic cholinergic, and D2 dopamine receptors in intact cells, suggesting that these elements critically contribute to the energy of the interaction. Thus, in contrast to arrestin-1, where direct phosphate binding is crucial, the interaction of non-visual arrestins with their cognate receptors depends to a lesser extent on phosphate binding and more on the binding to non-phosphorylated receptor elements.
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27
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Kim M, Hanson SM, Vishnivetskiy SA, Song X, Cleghorn WM, Hubbell WL, Gurevich VV. Robust self-association is a common feature of mammalian visual arrestin-1. Biochemistry 2011; 50:2235-42. [PMID: 21288033 DOI: 10.1021/bi1018607] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Arrestin-1 binds light-activated phosphorhodopsin and ensures rapid signal termination. Its deficiency in humans and mice results in prolonged signaling and rod degeneration. However, most of the biochemical studies were performed on bovine arrestin-1, which was shown to self-associate forming dimers and tetramers, although only the monomer binds rhodopsin. It is unclear whether self-association is a property of arrestin-1 in all mammals or a specific feature of bovine protein. To address this issue, we compared self-association parameters of purified human and mouse arrestin-1 with those of its bovine counterpart using multiangle light scattering. We found that mouse and human arrestin-1 also robustly self-associate, existing in a monomer-dimer-tetramer equilibrium. Interestingly, the combination of dimerization and tetramerization constants in these three species is strikingly different. While tetramerization of bovine arrestin-1 is highly cooperative (K(D,dim)(4) > K(D,tet)), K(D,dim) ∼ K(D,tet) in the mouse form and K(D,dim) ≪ K(D,tet) in the human form. Importantly, in all three species at very high physiological concentrations of arrestin-1 in rod photoreceptors, most of it is predicted to exist in oligomeric form, with a relatively low concentration of the free monomer. Thus, it appears that maintenance of low levels of the active monomer is the biological role of arrestin-1 self-association.
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Affiliation(s)
- Miyeon Kim
- University of California, Los Angeles, California 90095, United States
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28
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Zhan X, Gimenez LE, Gurevich VV, Spiller BW. Crystal structure of arrestin-3 reveals the basis of the difference in receptor binding between two non-visual subtypes. J Mol Biol 2011; 406:467-78. [PMID: 21215759 DOI: 10.1016/j.jmb.2010.12.034] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 12/02/2010] [Accepted: 12/21/2010] [Indexed: 12/13/2022]
Abstract
Arrestins are multi-functional proteins that regulate signaling and trafficking of the majority of G protein-coupled receptors (GPCRs), as well as sub-cellular localization and activity of many other signaling proteins. We report the first crystal structure of arrestin-3, solved at 3.0 Å resolution. Arrestin-3 is an elongated two-domain molecule with overall fold and key inter-domain interactions that hold the free protein in the basal conformation similar to the other subtypes. Arrestin-3 is the least selective member of the family, binding a wide variety of GPCRs with high affinity and demonstrating lower preference for active phosphorylated forms of the receptors. In contrast to the other three arrestins, part of the receptor-binding surface in the arrestin-3 C-domain does not form a contiguous β-sheet, which is consistent with increased flexibility. By swapping the corresponding elements between arrestin-2 and arrestin-3 we show that the presence of this loose structure is correlated with reduced arrestin selectivity for activated receptors, consistent with a conformational change in this β-sheet upon receptor binding.
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Affiliation(s)
- Xuanzhi Zhan
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
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29
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Feng X, Wang W, Liu J, Liu Y. β-Arrestins: multifunctional signaling adaptors in type 2 diabetes. Mol Biol Rep 2010; 38:2517-28. [PMID: 21086182 DOI: 10.1007/s11033-010-0389-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 11/08/2010] [Indexed: 02/06/2023]
Abstract
β-arrestins are not only well-known negative regulators of G protein-coupled receptor (GPCR) signaling, but also important adaptors in modulating the strength and duration of cellular signaling by scaffolding and interacting with a lot of cytoplasmic proteins. While β-arrestins are rather well described signal-mediated molecules, they are not generally associated with insulin signaling. But recent work has confirmed the difference from original thought. The current review aims to explore the emerging roles for β-arrestins in regulating insulin action, inflammatory signal pathway and other cellular signaling which are associated with type 2 diabetes.
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Affiliation(s)
- Xiaotao Feng
- Institute of Chinese Integrative Medicine, Huashan Hospital, Fudan University, No.12 Wulumuqi Zhong Road, Shanghai, 200040, China
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30
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Zhuang T, Vishnivetskiy SA, Gurevich VV, Sanders CR. Elucidation of inositol hexaphosphate and heparin interaction sites and conformational changes in arrestin-1 by solution nuclear magnetic resonance. Biochemistry 2010; 49:10473-85. [PMID: 21050017 DOI: 10.1021/bi101596g] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Arrestins specifically bind activated and phosphorylated G protein-coupled receptors and orchestrate both receptor trafficking and channel signaling through G protein-independent pathways via direct interactions with numerous nonreceptor partners. Here we report the first successful use of solution NMR in mapping the binding sites in arrestin-1 (visual arrestin) for two polyanionic compounds that mimic phosphorylated light-activated rhodopsin: inositol hexaphosphate (IP6) and heparin. This yielded an identification of residues involved in the binding with these ligands that was more complete than what has previously been feasible. IP6 and heparin appear to bind to the same site on arrestin-1, centered on a positively charged region in the N-domain. We present the first direct evidence that both IP6 and heparin induced a complete release of the arrestin C-tail. These observations provide novel insight into the nature of the transition of arrestin from the basal to active state and demonstrate the potential of NMR-based methods in the study of protein-protein interactions involving members of the arrestin family.
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Affiliation(s)
- Tiandi Zhuang
- Department of Biochemistry, Vanderbilt University School ofMedicine, Nashville, Tennessee 37232, United States
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31
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Song X, Vishnivetskiy SA, Seo J, Chen J, Gurevich EV, Gurevich VV. Arrestin-1 expression level in rods: balancing functional performance and photoreceptor health. Neuroscience 2010; 174:37-49. [PMID: 21075174 DOI: 10.1016/j.neuroscience.2010.11.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 10/31/2010] [Accepted: 11/06/2010] [Indexed: 12/16/2022]
Abstract
In rod photoreceptors, signaling persists as long as rhodopsin remains catalytically active. Phosphorylation by rhodopsin kinase followed by arrestin-1 binding completely deactivates rhodopsin. Timely termination prevents excessive signaling and ensures rapid recovery. Mouse rods express arrestin-1 and rhodopsin at ∼0.8:1 ratio, making arrestin-1 the second most abundant protein in the rod. The biological significance of wild type arrestin-1 expression level remains unclear. Here we investigated the effects of varying arrestin-1 expression on its intracellular distribution in dark-adapted photoreceptors, rod functional performance, recovery kinetics, and morphology. We found that rod outer segments isolated from dark-adapted animals expressing arrestin-1 at wild type or higher level contain much greater fraction of arrestin-1 than previously estimated, 15-25% of the total. The fraction of arrestin-1 residing in the outer segments (OS) in animals with low expression (4-12% of wild type) is much lower, 5-7% of the total. Only 4% of wild type arrestin-1 level in the outer segments was sufficient to maintain near-normal retinal morphology, whereas rapid recovery required at least ∼12%. Supra-physiological arrestin-1 expression improved light sensitivity and facilitated photoresponse recovery, but was detrimental for photoreceptor health, particularly in the peripheral retina. Thus, physiological level of arrestin-1 expression in rods reflects the balance between short-term functional performance of photoreceptors and their long-term health.
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Affiliation(s)
- X Song
- Vanderbilt University, Nashville, TN 37232, USA
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32
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Abstract
Multiple genetic disorders can be associated with excessive signalling by mutant G-protein-coupled receptors (GPCRs) that are either constitutively active or have lost sites where phosphorylation by GPCR kinases is necessary for desensitisation by cognate arrestins. Phosphorylation-independent arrestin1 can compensate for defects in phosphorylation of the GPCR rhodopsin in retinal rod cells, facilitating recovery, improving light responsiveness, and promoting photoreceptor survival. These proof-of-principle experiments show that, based on mechanistic understanding of the inner workings of a protein, one can modify its functional characteristics to generate custom-designed mutants that improve the balance of signalling in congenital and acquired disorders. Manipulations of arrestin elements responsible for scaffolding mitogen-activated protein kinase cascades and binding other signalling proteins involved in life-or-death decisions in the cell are likely to yield mutants that affect cell survival and proliferation in the desired direction. Although this approach is still in its infancy, targeted redesign of individual functions of many proteins offers a promise of a completely new therapeutic toolbox with huge potential.
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Tsukamoto H, Sinha A, DeWitt M, Farrens DL. Monomeric rhodopsin is the minimal functional unit required for arrestin binding. J Mol Biol 2010; 399:501-11. [PMID: 20417217 DOI: 10.1016/j.jmb.2010.04.029] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 04/13/2010] [Accepted: 04/16/2010] [Indexed: 11/19/2022]
Abstract
We have tested whether arrestin binding requires the G-protein-coupled receptor be a dimer or a multimer. To do this, we encapsulated single-rhodopsin molecules into nanoscale phospholipid particles (so-called nanodiscs) and measured their ability to bind arrestin. Our data clearly show that both visual arrestin and beta-arrestin 1 can bind to monomeric rhodopsin and stabilize the active metarhodopsin II form. Interestingly, we find that the monomeric rhodopsin in nanodiscs has a higher affinity for wild-type arrestin binding than does oligomeric rhodopsin in liposomes or nanodiscs, as assessed by stabilization of metarhodopsin II. Together, these results establish that rhodopsin self-association is not required to enable arrestin binding.
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Affiliation(s)
- Hisao Tsukamoto
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, USA
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34
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Arrestin competition influences the kinetics and variability of the single-photon responses of mammalian rod photoreceptors. J Neurosci 2009; 29:11867-79. [PMID: 19776273 DOI: 10.1523/jneurosci.0819-09.2009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Reliable signal transduction via G-protein-coupled receptors requires proper receptor inactivation. For example, signals originating from single rhodopsin molecules vary little from one to the next, requiring reproducible inactivation of rhodopsin by phosphorylation and arrestin binding. We determined how reduced concentrations of rhodopsin kinase (GRK1) and/or arrestin1 influenced the kinetics and variability of the single-photon responses of mouse rod photoreceptors. These experiments revealed that arrestin, in addition to its role in quenching the activity of rhodopsin, can tune the kinetics of rhodopsin phosphorylation by competing with GRK1. This competition influenced the variability of the active lifetime of rhodopsin. Biasing the competition in favor of GRK1 revealed that rhodopsin remained active through much of the single-photon response under the conditions of our experiments. This long-lasting rhodopsin activity can explain the characteristic time course of single-photon response variability. Indeed, explaining the late time-to-peak of the variance required an active lifetime of rhodopsin approximately twice that of the G-protein transducin. Competition between arrestins and kinases may be a general means of influencing signals mediated by G-protein-coupled receptors, particularly when activation of a few receptors produces signals of functional importance.
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35
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Hanson SM, Dawson ES, Francis DJ, Van Eps N, Klug CS, Hubbell WL, Meiler J, Gurevich VV. A model for the solution structure of the rod arrestin tetramer. Structure 2008; 16:924-34. [PMID: 18547524 DOI: 10.1016/j.str.2008.03.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 03/03/2008] [Accepted: 03/04/2008] [Indexed: 10/22/2022]
Abstract
Visual rod arrestin has the ability to self-associate at physiological concentrations. We previously demonstrated that only monomeric arrestin can bind the receptor and that the arrestin tetramer in solution differs from that in the crystal. We employed the Rosetta docking software to generate molecular models of the physiologically relevant solution tetramer based on the monomeric arrestin crystal structure. The resulting models were filtered using the Rosetta energy function, experimental intersubunit distances measured with DEER spectroscopy, and intersubunit contact sites identified by mutagenesis and site-directed spin labeling. This resulted in a unique model for subsequent evaluation. The validity of the model is strongly supported by model-directed crosslinking and targeted mutagenesis that yields arrestin variants deficient in self-association. The structure of the solution tetramer explains its inability to bind rhodopsin and paves the way for experimental studies of the physiological role of rod arrestin self-association.
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Affiliation(s)
- Susan M Hanson
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
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36
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Mokarzel-Falcón L, Padrón-García JA, Carrasco-Velar R, Berry C, Montero-Cabrera LA. In silico study of the human rhodopsin and meta rhodopsin II/S-arrestin complexes: impact of single point mutations related to retina degenerative diseases. Proteins 2008; 70:1133-41. [PMID: 18175313 DOI: 10.1002/prot.21873] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We propose two models of the human S-arrestin/rhodopsin complex in the inactive dark adapted rhodopsin and meta rhodopsin II form, obtained by homology modeling and knowledge based docking. First, a homology model for the human S-arrestin was built and validated by molecular dynamics, showing an average root mean square deviation difference from the pattern behavior of 0.76 A. Then, combining the human S-arrestin model and the modeled structure of the two human rhodopsin forms, we propose two models of interaction for the human S-arrestin/rhodopsin complex. The models involve two S-arrestin regions related to the N domain (residues 68-78; 170-182) and a third constituent of the C domain (248-253), with the rhodopsin C terminus (330-348). Of the 22 single point mutations related to retinitis pigmentosa and congenital night blindness located in the cytoplasmatic portion of rhodopsin or in S-arrestin, our models locate 16 in the interaction region and relate two others to possible dimer formation. Our calculations also predict that the light activated complex is more stable than the dark adapted rhodopsin and, therefore, of higher affinity to S-arrestin.
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37
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Analysis of self-associating proteins by singular value decomposition of solution scattering data. Biophys J 2008; 94:4906-23. [PMID: 18212017 DOI: 10.1529/biophysj.107.113167] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe a method by which a single experiment can reveal both association model (pathway and constants) and low-resolution structures of a self-associating system. Small-angle scattering data are collected from solutions at a range of concentrations. These scattering data curves are mass-weighted linear combinations of the scattering from each oligomer. Singular value decomposition of the data yields a set of basis vectors from which the scattering curve for each oligomer is reconstructed using coefficients that depend on the association model. A search identifies the association pathway and constants that provide the best agreement between reconstructed and observed data. Using simulated data with realistic noise, our method finds the correct pathway and association constants. Depending on the simulation parameters, reconstructed curves for each oligomer differ from the ideal by 0.05-0.99% in median absolute relative deviation. The reconstructed scattering curves are fundamental to further analysis, including interatomic distance distribution calculation and low-resolution ab initio shape reconstruction of each oligomer in solution. This method can be applied to x-ray or neutron scattering data from small angles to moderate (or higher) resolution. Data can be taken under physiological conditions, or particular conditions (e.g., temperature) can be varied to extract fundamental association parameters (DeltaH(ass), DeltaS(ass)).
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38
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Hanson SM, Vishnivetskiy SA, Hubbell WL, Gurevich VV. Opposing effects of inositol hexakisphosphate on rod arrestin and arrestin2 self-association. Biochemistry 2007; 47:1070-5. [PMID: 18161994 DOI: 10.1021/bi7021359] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The robust cooperative formation of rod arrestin tetramers has been well-established, whereas the ability of other members of the arrestin family to self-associate remains controversial. Here, we used purified arrestins and multi-angle light scattering to quantitatively compare the propensity of the four mammalian arrestin subtypes to self-associate. Both non-visual and cone arrestins only form oligomers at very high non-physiological concentrations. However, inositol hexakisphosphate (IP6), a fairly abundant form of inositol in the cytoplasm, greatly facilitates self-association of arrestin2. Arrestin2 self-association equilibrium constants in the presence of 100 microM IP6 suggest that an appreciable proportion could exist in an oligomeric state but only in intracellular compartments where its concentration is 5-10-fold higher than average. In contrast to arrestin2, IP6 inhibits self-association of rod arrestin, indicating that the structure of these two tetramers in solution is likely different.
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Affiliation(s)
- Susan M Hanson
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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39
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Vishnivetskiy SA, Raman D, Wei J, Kennedy MJ, Hurley JB, Gurevich VV. Regulation of arrestin binding by rhodopsin phosphorylation level. J Biol Chem 2007; 282:32075-83. [PMID: 17848565 PMCID: PMC2638115 DOI: 10.1074/jbc.m706057200] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arrestins ensure the timely termination of receptor signaling. The role of rhodopsin phosphorylation in visual arrestin binding was established more than 20 years ago, but the effects of the number of receptor-attached phosphates on this interaction remain controversial. Here we use purified rhodopsin fractions with carefully quantified content of individual phosphorylated rhodopsin species to elucidate the impact of phosphorylation level on arrestin interaction with three biologically relevant functional forms of rhodopsin: light-activated and dark phosphorhodopsin and phospho-opsin. We found that a single receptor-attached phosphate does not facilitate arrestin binding, two are necessary to induce high affinity interaction, and three phosphates fully activate arrestin. Higher phosphorylation levels do not increase the stability of arrestin complex with light-activated rhodopsin but enhance its binding to the dark phosphorhodopsin and phospho-opsin. The complex of arrestin with hyperphosphorylated light-activated rhodopsin is less sensitive to high salt and appears to release retinal faster. These data suggest that arrestin likely quenches rhodopsin signaling after the third phosphate is added by rhodopsin kinase. The complex of arrestin with heavily phosphorylated rhodopsin, which appears to form in certain disease states, has distinct characteristics that may contribute to the phenotype of these visual disorders.
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Affiliation(s)
| | - Dayanidhi Raman
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232
| | - Junhua Wei
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Matthew J. Kennedy
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - James B. Hurley
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
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40
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Hanson SM, Van Eps N, Francis DJ, Altenbach C, Vishnivetskiy SA, Arshavsky VY, Klug CS, Hubbell WL, Gurevich VV. Structure and function of the visual arrestin oligomer. EMBO J 2007; 26:1726-36. [PMID: 17332750 PMCID: PMC1829381 DOI: 10.1038/sj.emboj.7601614] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 01/26/2007] [Indexed: 01/24/2023] Open
Abstract
A distinguishing feature of rod arrestin is its ability to form oligomers at physiological concentrations. Using visible light scattering, we show that rod arrestin forms tetramers in a cooperative manner in solution. To investigate the structure of the tetramer, a nitroxide side chain (R1) was introduced at 18 different positions. The effects of R1 on oligomer formation, EPR spectra, and inter-spin distance measurements all show that the structures of the solution and crystal tetramers are different. Inter-subunit distance measurements revealed that only arrestin monomer binds to light-activated phosphorhodopsin, whereas both monomer and tetramer bind microtubules, which may serve as a default arrestin partner in dark-adapted photoreceptors. Thus, the tetramer likely serves as a 'storage' form of arrestin, increasing the arrestin-binding capacity of microtubules while readily dissociating to supply active monomer when it is needed to quench rhodopsin signaling.
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Affiliation(s)
- Susan M Hanson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Ned Van Eps
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA, USA
| | - Derek J Francis
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Christian Altenbach
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA, USA
| | | | - Vadim Y Arshavsky
- Albert Eye Research Institute, Duke University Medical Center, Durham, NC, USA
| | - Candice S Klug
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Tel.: +1 414 456 4015; Fax: +1 414 456 6512; E-mail:
| | - Wayne L Hubbell
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA, USA
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA; Tel.: +1 310 206 8830; Fax: +1 310 794 2144; E-mail:
| | - Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA. Tel.: +1 615 322 7070; Fax: +1 615 343 6532; E-mail:
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41
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Hanson SM, Gurevich EV, Vishnivetskiy SA, Ahmed MR, Song X, Gurevich VV. Each rhodopsin molecule binds its own arrestin. Proc Natl Acad Sci U S A 2007; 104:3125-8. [PMID: 17360618 PMCID: PMC1805568 DOI: 10.1073/pnas.0610886104] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Indexed: 11/18/2022] Open
Abstract
Arrestins (Arrs) are ubiquitous regulators of the most numerous family of signaling proteins, G protein-coupled receptors. Two models of the Arr-receptor interaction have been proposed: the binding of one Arr to an individual receptor or to two receptors in a dimer. To determine the binding stoichiometry in vivo, we used rod photoreceptors where rhodopsin (Rh) and Arr are expressed at comparably high levels and where Arr localization in the light is determined by its binding to activated Rh. Genetic manipulation of the expression of both proteins shows that the maximum amount of Arr that moves to the Rh-containing compartment exceeds 80%, but not 100%, of the molar amount of Rh present. In vitro experiments with purified proteins confirm that Arr "saturates" Rh at a 1:1 ratio. Thus, a single Rh molecule is necessary and sufficient to bind Arr. Remarkable structural conservation among receptors and Arrs strongly suggests that all Arr subtypes bind individual molecules of their cognate receptors.
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Affiliation(s)
- Susan M. Hanson
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, PRB, Room 418, Nashville, TN 37232
| | - Eugenia V. Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, PRB, Room 418, Nashville, TN 37232
| | - Sergey A. Vishnivetskiy
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, PRB, Room 418, Nashville, TN 37232
| | - Mohamed R. Ahmed
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, PRB, Room 418, Nashville, TN 37232
| | - Xiufeng Song
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, PRB, Room 418, Nashville, TN 37232
| | - Vsevolod V. Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, PRB, Room 418, Nashville, TN 37232
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42
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Dolenc I, Pain R, Turk V. Presence of the propeptide on recombinant lysosomal dipeptidase controls both activation and dimerization. Biol Chem 2007; 388:47-51. [PMID: 17214548 DOI: 10.1515/bc.2007.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Lysosomal dipeptidase catalyzes the hydrolysis of dipeptides with unsubstituted terminals. It is a homodimer and binds zinc. Dimerization is an important issue in understanding the enzyme's function. In this study, we investigated the influence of the propeptide on the folding and dimerization of recombinant lysosomal dipeptidase. For this purpose, we separately cloned and overexpressed the mature protein and the proenzyme. The overexpressed proteins were localized exclusively to insoluble inclusion bodies. Refolding of the urea-solubilized inclusion bodies showed that only dipeptidase lacking the propeptide was dimeric. The soluble renatured proenzyme was a monomer, although circular dichroism and fluorescence spectra of the proenzyme indicated the formation of secondary and tertiary structure. The propeptide thus controls dimerization, as well as activation, of lysosomal dipeptidase.
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Affiliation(s)
- Iztok Dolenc
- Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
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43
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Sommer ME, Farrens DL. Arrestin can act as a regulator of rhodopsin photochemistry. Vision Res 2006; 46:4532-46. [PMID: 17069872 PMCID: PMC2877124 DOI: 10.1016/j.visres.2006.08.031] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 08/11/2006] [Accepted: 08/16/2006] [Indexed: 11/24/2022]
Abstract
We report that visual arrestin can regulate retinal release and late photoproduct formation in rhodopsin. Our experiments, which employ a fluorescently labeled arrestin and rhodopsin solubilized in detergent/phospholipid micelles, indicate that arrestin can trap a population of retinal in the binding pocket with an absorbance characteristic of Meta II with the retinal Schiff-base intact. Furthermore, arrestin can convert Metarhodopsin III (formed either by thermal decay or blue-light irradiation) to a Meta II-like absorbing species. Together, our results suggest arrestin may be able to play a more complex role in the rod cell besides simply quenching transducin activity. This possibility may help explain why arrestin deficiency leads to problems like stationary night blindness (Oguchi disease) and retinal degeneration.
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Affiliation(s)
| | - David L. Farrens
- Corresponding author. Fax: +1 503 494 8393. E-mail address: (D.L. Farrens)
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44
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Hanson SM, Francis DJ, Vishnivetskiy SA, Klug CS, Gurevich VV. Visual arrestin binding to microtubules involves a distinct conformational change. J Biol Chem 2006; 281:9765-72. [PMID: 16461350 PMCID: PMC2430877 DOI: 10.1074/jbc.m510738200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recently we found that visual arrestin binds microtubules and that this interaction plays an important role in arrestin localization in photoreceptor cells. Here we use site-directed mutagenesis and spin labeling to explore the molecular mechanism of this novel regulatory interaction. The microtubule binding site maps to the concave sides of the two arrestin domains, overlapping with the rhodopsin binding site, which makes arrestin interactions with rhodopsin and microtubules mutually exclusive. Arrestin interaction with microtubules is enhanced by several "activating mutations" and involves multiple positive charges and hydrophobic elements. The comparable affinity of visual arrestin for microtubules and unpolymerized tubulin (K(D) > 40 mum and >65 mum, respectively) suggests that the arrestin binding site is largely localized on the individual alphabeta-dimer. The changes in the spin-spin interaction of a double-labeled arrestin indicate that the conformation of microtubule-bound arrestin differs from that of free arrestin in solution. In sharp contrast to rhodopsin, where tight binding requires an extended interdomain hinge, arrestin binding to microtubules is enhanced by deletions in this region, suggesting that in the process of microtubule binding the domains may move in the opposite direction. Thus, microtubule and rhodopsin binding induce different conformational changes in arrestin, suggesting that arrestin assumes three distinct conformations in the cell, likely with different functional properties.
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Affiliation(s)
- Susan M. Hanson
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Derek J. Francis
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Sergey A. Vishnivetskiy
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Candice S. Klug
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Vsevolod V. Gurevich
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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45
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Milano SK, Kim YM, Stefano FP, Benovic JL, Brenner C. Nonvisual arrestin oligomerization and cellular localization are regulated by inositol hexakisphosphate binding. J Biol Chem 2006; 281:9812-23. [PMID: 16439357 DOI: 10.1074/jbc.m512703200] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interactions between arrestins and phosphoinositides have been reported to regulate multiple membrane-associated signaling and trafficking events including clathrin-mediated endocytosis and light adaptation in Drosophila. Arrestins have been proposed to have nuclear and cytosolic functions as well, although the ligand dependence of these functions has not been investigated. Here we characterize the structural, molecular, and cellular interactions between arrestin-2 and inositol hexakisphosphate (inositol 1,2,3,4,5,6-hexakisphosphate (IP(6))). The crystal structure of the arrestin-2.IP(6) complex was solved to 2.9 A with crystal lattice contacts suggesting two sites on a protein monomer mediating IP(6) binding. Mutagenesis coupled to isothermal titration calorimetry and tritiated IP(6) binding assays confirmed two-site binding with a low affinity IP(6)-binding site in the N-domain and a high affinity site in the C-domain. Native gel electrophoresis, gel filtration, and analytical ultracentrifugation demonstrated the ability of IP(6) to promote arrestin-2 oligomerization via the two crystallographically defined ligand-binding locations. In addition, analysis in mammalian cells revealed that arrestin-2 not only undergoes homo-oligomerization, but it can also hetero-oligomerize with arrestin-3 in a manner that depends on IP(6)-binding sites. Mutation of either IP(6)-binding site in arrestin-2 disrupted oligomerization while interactions with known binding partners including clathrin, AP-2, and ERK2 were maintained. Subcellular localization studies showed that arrestin-2 oligomers are primarily cytoplasmic, whereas arrestin-2 monomers displayed increased nuclear localization. Thus, by promoting cytosolic oligomerization, IP(6) binding is proposed to be a negative regulator of interactions of arrestin with plasma membrane and nuclear signaling proteins.
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Affiliation(s)
- Shawn K Milano
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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46
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Sommer ME, Smith WC, Farrens DL. Dynamics of arrestin-rhodopsin interactions: arrestin and retinal release are directly linked events. J Biol Chem 2004; 280:6861-71. [PMID: 15591052 DOI: 10.1074/jbc.m411341200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we address the mechanism of visual arrestin release from light-activated rhodopsin using fluorescently labeled arrestin mutants. We find that two mutants, I72C and S251C, when labeled with the small, solvent-sensitive fluorophore monobromobimane, exhibit spectral changes only upon binding light-activated, phosphorylated rhodopsin. Our analysis indicates that these changes are probably due to a burying of the probes at these sites in the rhodopsin-arrestin or phospholipid-arrestin interface. Using a fluorescence approach based on this observation, we demonstrate that arrestin and retinal release are linked and are described by similar activation energies. However, at physiological temperatures, we find that arrestin slows the rate of retinal release approximately 2-fold and abolishes the pH dependence of retinal release. Using fluorescence, EPR, and biochemical approaches, we also find intriguing evidence that arrestin binds to a post-Meta II photodecay product, possibly Meta III. We speculate that arrestin regulates levels of free retinal in the rod cell to help limit the formation of damaging oxidative retinal adducts. Such adducts may contribute to diseases like atrophic age-related macular degeneration (AMD). Thus, arrestin may serve to both attenuate rhodopsin signaling and protect the cell from excessive retinal levels under bright light conditions.
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Affiliation(s)
- Martha E Sommer
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239-3098, USA
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47
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Warren JS. Intrapulmonary interleukin 1 mediates acute immune complex alveolitis in the rat. Biochem Biophys Res Commun 1991; 23:17-22. [PMID: 1826836 DOI: 10.1152/physiol.00042.2007] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interleukin 1 alpha and beta are polypeptide cytokines that possesses a wide variety of immunologic and inflammatory activities. We have examined the role of intrapulmonary interleukin 1 in the pathogenesis of acute IgG immune complex alveolitis in the rat. Intratracheal instillation of IgG anti-bovine serum albumin accompanied by intravenous infusion of bovine albumin results in acute neutrophil and complement-dependent alveolitis. Over the course of evolving lung injury there was a 12-fold increase in bronchoalveolar lavage fluid interleukin 1 activity. Intratracheal instillation of neutralizing anti-interleukin 1 beta antibodies upon induction of lung injury resulted in a dose-dependent reduction in lung injury as assessed by measurements of pulmonary hemorrhage and vascular permeability. Morphometric analysis and measurements of myeloperoxidase activities in whole lung homogenates from rats that received anti-interleukin 1 beta revealed a pronounced reduction in neutrophil recruitment compared to positive controls. Incubation of isolated alveolar macrophages with preformed IgG immune complexes resulted in dose-dependent interleukin 1 secretion. These data suggest that intrapulmonary IL-1 activity plays a role in neutrophil recruitment and is necessary for the full development of acute IgG immune complex induced lung injury in the rat.
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Affiliation(s)
- J S Warren
- Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602
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