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Chae K, Overcash JM, Dawson C, Valentin C, Tsujimoto H, Myles KM, Adelman ZN. CRISPR-based gene editing of non-homologous end joining factors biases DNA repair pathway choice toward single-strand annealing in Aedes aegypti. Curr Res Biotechnol 2023; 5:100133. [PMID: 37475832 PMCID: PMC10357993 DOI: 10.1016/j.crbiot.2023.100133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023] Open
Abstract
To maintain genome stability, eukaryotic cells orchestrate DNA repair pathways to process DNA double-strand breaks (DSBs) that result from diverse developmental or environmental stimuli. Bias in the selection of DSB repair pathways, either non-homologous end joining (NHEJ) or homology-directed repair (HDR), is also critical for efficient gene editing and for homing-based gene drive approaches developed for the control of disease-transmitting vector mosquitoes. However, little is understood about DNA repair homeostasis in the mosquito genome. Here, we utilized CRISPR/Cas9 to generate indel mutant strains for core NHEJ factors ku80, DNA ligase IV (lig4), and DNA-PKcs in the mosquito Aedes aegypti and evaluated the corresponding effects on DNA repair. In a plasmid-based assay, disruption of ku80 or lig4, but not DNA-PKcs, reduced both NHEJ and SSA. However, a transgenic reporter strain-based test revealed that those mutations significantly biased DNA repair events toward SSA. Interestingly, ku80 mutation also significantly increased the end joining rate by a yet-characterized mechanism in males. Our study provides evidence that the core NHEJ factors have an antagonistic effect on SSA-based DSB repair of the Ae. aegypti genome. Down-modulating the NHEJ pathway can enhance the efficiency of nuclease-based genetic control approaches, as most of those operate by homology-based repair processes along with extensive DNA end resection that is antagonized by NHEJ.
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Affiliation(s)
- Keun Chae
- Department of Entomology, Texas A&M University, College Station, TX 77843, United States
| | - Justin M. Overcash
- U.S. Department of Agriculture-Animal and Plant Health Inspection Service (USDA-APHIS), Biotechnology Regulatory Services, Riverdale, MD 20737, United States
| | - Chanell Dawson
- Department of Entomology, Texas A&M University, College Station, TX 77843, United States
| | - Collin Valentin
- Department of Entomology, Texas A&M University, College Station, TX 77843, United States
| | - Hitoshi Tsujimoto
- Department of Entomology, Texas A&M University, College Station, TX 77843, United States
| | - Kevin M. Myles
- Department of Entomology, Texas A&M University, College Station, TX 77843, United States
| | - Zach N. Adelman
- Department of Entomology, Texas A&M University, College Station, TX 77843, United States
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Contreras B, Adelman ZN, Chae K. Evaluating the Mating Competency of Genetically Modified Male Mosquitoes in Laboratory Conditions. Front Trop Dis 2023; 4:1106671. [PMID: 37860147 PMCID: PMC10586724 DOI: 10.3389/fitd.2023.1106671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023] Open
Abstract
Efforts to eradicate mosquito-borne diseases have increased the demand for genetic control strategies, many of which involve the release of genetically modified (GM) mosquito males into natural populations. The first hurdle for GM males is to compete with their wild-type counterparts for access to females. Here, we introduce an eye color-based mating assay, in which both Lvp wild-type and kynurenine 3-monooxygenase (kmo)-null males compete for access to kmo-null females, and therefore the eye color phenotype (black or white) of the progeny is dependent on the parental mating pair. A series of tests addressed that male mating competitiveness between the two strains can significantly be influenced by adult density, light intensity, and mating duration. Interestingly, the mating competitiveness of males was not correlated with body size, which was negatively influenced by a high larval density. Lastly, this eye color-associated assay was applied to characterize GM mosquitoes in their mating competitiveness, establishing this method as a fast and precise way of benchmarking this fitness parameter for laboratory-raised males.
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Affiliation(s)
- Bryan Contreras
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Zach N. Adelman
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Keun Chae
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
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Nagpal P, Reeves PH, Wong JH, Armengot L, Chae K, Rieveschl NB, Trinidad B, Davidsdottir V, Jain P, Gray WM, Jaillais Y, Reed JW. SAUR63 stimulates cell growth at the plasma membrane. PLoS Genet 2022; 18:e1010375. [PMID: 36121899 PMCID: PMC9522268 DOI: 10.1371/journal.pgen.1010375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 09/29/2022] [Accepted: 08/04/2022] [Indexed: 11/20/2022] Open
Abstract
In plants, regulated cell expansion determines organ size and shape. Several members of the family of redundantly acting Small Auxin Up RNA (SAUR) proteins can stimulate plasma membrane (PM) H+-ATPase proton pumping activity by inhibiting PM-associated PP2C.D phosphatases, thereby increasing the PM electrochemical potential, acidifying the apoplast, and stimulating cell expansion. Similarly, Arabidopsis thaliana SAUR63 was able to increase growth of various organs, antagonize PP2C.D5 phosphatase, and increase H+-ATPase activity. Using a gain-of-function approach to bypass genetic redundancy, we dissected structural requirements for SAUR63 growth-promoting activity. The divergent N-terminal domain of SAUR63 has a predicted basic amphipathic α-helix and was able to drive partial PM association. Deletion of the N-terminal domain decreased PM association of a SAUR63 fusion protein, as well as decreasing protein level and eliminating growth-promoting activity. Conversely, forced PM association restored ability to promote H+-ATPase activity and cell expansion, indicating that SAUR63 is active when PM-associated. Lipid binding assays and perturbations of PM lipid composition indicate that the N-terminal domain can interact with PM anionic lipids. Mutations in the conserved SAUR domain also reduced PM association in root cells. Thus, both the N-terminal domain and the SAUR domain may cooperatively mediate the SAUR63 PM association required to promote growth. Plant organs reach their final shape and size after substantial cell expansion. Proton pumps at the plasma membrane promote cell expansion by acidifying the cell wall to loosen it, and by increasing electrochemical potential across the plasma membrane for solute uptake that maintains intracellular turgor. Plasma-membrane-associated proteins tightly regulate proton pump activity, in order for organs to grow to an appropriate extent. We have studied requirements for activity of one such regulatory protein in the model plant Arabidopsis called SAUR63. This protein is made rapidly in response to plant growth hormones, and it increases proton pump activity to promote organ growth. These activities depend on its binding to anionic lipids in the plasma membrane, and forced plasma membrane association of SAUR63 can increase growth. Many proteins in the same family are found within Arabidopsis and in all land plants, and likely differ in their affinity for the plasma membrane or in other properties. Further studies of other family members may show how such proteins regulate growth under diverse physiological contexts.
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Affiliation(s)
- Punita Nagpal
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon, France
| | - Paul H. Reeves
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jeh Haur Wong
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Laia Armengot
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon, France
| | - Keun Chae
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Nathaniel B. Rieveschl
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Brendan Trinidad
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Vala Davidsdottir
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Prateek Jain
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - William M. Gray
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Yvon Jaillais
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon, France
| | - Jason W. Reed
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon, France
- * E-mail:
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Budner T, Friedman M, Wrede C, Brown BA, José J, Pérez-Loureiro D, Sun LJ, Surbrook J, Ayyad Y, Bardayan DW, Chae K, Chen AA, Chipps KA, Cortesi M, Glassman B, Hall MR, Janasik M, Liang J, O'Malley P, Pollacco E, Psaltis A, Stomps J, Wheeler T. Constraining the ^{30}P(p, γ)^{31}S Reaction Rate in ONe Novae via the Weak, Low-Energy, β-Delayed Proton Decay of ^{31}Cl. Phys Rev Lett 2022; 128:182701. [PMID: 35594108 DOI: 10.1103/physrevlett.128.182701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 01/14/2022] [Accepted: 04/04/2022] [Indexed: 06/15/2023]
Abstract
The ^{30}P(p,γ)^{31}S reaction plays an important role in understanding the nucleosynthesis of A≥30 nuclides in oxygen-neon novae. The Gaseous Detector with Germanium Tagging was used to measure ^{31}Cl β-delayed proton decay through the key J^{π}=3/2^{+}, 260-keV resonance. The intensity I_{βp}^{260}=8.3_{-0.9}^{+1.2}×10^{-6} represents the weakest β-delayed, charged-particle emission ever measured below 400 keV, resulting in a proton branching ratio of Γ_{p}/Γ=2.5_{-0.3}^{+0.4}×10^{-4}. By combining this measurement with shell-model calculations for Γ_{γ} and past work on other resonances, the total ^{30}P(p,γ)^{31}S rate has been determined with reduced uncertainty. The new rate has been used in hydrodynamic simulations to model the composition of nova ejecta, leading to a concrete prediction of ^{30}Si:^{28}Si excesses in presolar nova grains and the calibration of nuclear thermometers.
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Affiliation(s)
- T Budner
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - M Friedman
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- Racah Institute of Physics, Hebrew University, Jerusalem, Israel 91904
| | - C Wrede
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - B A Brown
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - J José
- Departament de Física, Universitat Politècnica de Catalunya, E-08019 Barcelona, Spain
- Institut d'Estudis Espacials de Catalunya, Universitat Politècnica de Catalunya, E-08034 Barcelona, Spain
| | - D Pérez-Loureiro
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - L J Sun
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - J Surbrook
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - Y Ayyad
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- IGFAE, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - D W Bardayan
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - K Chae
- Department of Physics, Sungkyunkwan University, Seoul 16419, South Korea
| | - A A Chen
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - K A Chipps
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830-37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M Cortesi
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - B Glassman
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - M R Hall
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - M Janasik
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - J Liang
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - P O'Malley
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - E Pollacco
- Département de Physique Nucléaire, IRFU, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette, France
| | - A Psaltis
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - J Stomps
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - T Wheeler
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
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Chae K, Dawson C, Valentin C, Contreras B, Zapletal J, Myles KM, Adelman ZN. Engineering a self-eliminating transgene in the yellow fever mosquito, Aedes aegypti. PNAS Nexus 2022; 1:pgac037. [PMID: 36713320 PMCID: PMC9802104 DOI: 10.1093/pnasnexus/pgac037] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/22/2022] [Indexed: 02/01/2023]
Abstract
Promising genetics-based approaches are being developed to reduce or prevent the transmission of mosquito-vectored diseases. Less clear is how such transgenes can be removed from the environment, a concern that is particularly relevant for highly invasive gene drive transgenes. Here, we lay the groundwork for a transgene removal system based on single-strand annealing (SSA), a eukaryotic DNA repair mechanism. An SSA-based rescuer strain (kmoRG ) was engineered to have direct repeat sequences (DRs) in the Aedes aegypti kynurenine 3-monooxygenase (kmo) gene flanking the intervening transgenic cargo genes, DsRED and EGFP. Targeted induction of DNA double-strand breaks (DSBs) in the DsRED transgene successfully triggered complete elimination of the entire cargo from the kmoRG strain, restoring the wild-type kmo gene, and thereby, normal eye pigmentation. Our work establishes the framework for strategies to remove transgene sequences during the evaluation and testing of modified strains for genetics-based mosquito control.
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Affiliation(s)
- Keun Chae
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Chanell Dawson
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Collin Valentin
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Bryan Contreras
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Josef Zapletal
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Kevin M Myles
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
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Chae K, Valentin C, Jakes E, Myles KM, Adelman ZN. Novel synthetic 3'-untranslated regions for controlling transgene expression in transgenic Aedes aegypti mosquitoes. RNA Biol 2021; 18:223-231. [PMID: 34464234 DOI: 10.1080/15476286.2021.1971440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Transgenic technology for mosquitoes is now more than two decades old, and a wide array of control sequences have been described for regulating gene expression in various life stages or specific tissues. Despite this, comparatively little attention has been paid to the development and validation of other transgene-regulating elements, especially 3'-untranslated regions (3'UTRs). As a consequence, the same regulatory sequences are often used multiple times in a single transgene array, potentially leading to instability of transgenic effector genes. To increase the repertoire of characterized 3'UTRs available for genetics-based mosquito control, we generated fifteen synthetic sequences based on the base composition of the widely used SV40 3'UTR sequence, and tested their ability to contribute to the expression of reporter genes EGFP or luciferase. Transient transfection in mosquito cells identified nine candidate 3'UTRs that conferred moderate to strong gene expression. Two of these were engineered into the mosquito genome through CRISPR/Cas9-mediated site-specific insertion and compared to the original SV40 3'UTR. Both synthetic 3'UTRs were shown to successfully promote transgene expression in all mosquito life stages (larva, pupa and adults), similar to the SV40 3'UTR, albeit with differences in intensity. Thus, the synthetic 3'UTR elements described here are suitable for regulating transgene expression in Ae. aegypti, and provide valuable alternatives in the design of multi-gene cassettes. Additionally, the synthetic-scramble approach we validate here could be used to generate additional functional 3'UTR elements in this or other organisms.
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Affiliation(s)
- Keun Chae
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Collin Valentin
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Emma Jakes
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Kevin M Myles
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Zach N Adelman
- Department of Entomology, Texas A&M University, College Station, TX, USA
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Chae K, Valentin C, Dawson C, Jakes E, Myles KM, Adelman ZN. A knockout screen of genes expressed specifically in Ae. aegypti pupae reveals a critical role for stretchin in mosquito flight. Insect Biochem Mol Biol 2021; 132:103565. [PMID: 33716097 DOI: 10.1016/j.ibmb.2021.103565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
Aedes aegypti is a critical vector for transmitting Zika, dengue, chikungunya, and yellow fever viruses to humans. Genetic strategies to limit mosquito survival based upon sex distortion or disruption of development may be valuable new tools to control Ae. aegypti populations. We identified six genes with expression limited to pupal development; osi8 and osi11 (Osiris protein family), CPRs and CPF (cuticle protein family), and stretchin (a muscle protein). Heritable CRISPR/Cas9-mediated gene knockout of these genes did not reveal any defects in pupal development. However, stretchin-null mutations (strnΔ35/Δ41) resulted in flightless mosquitoes with an abnormal open wing posture. The inability of adult strnΔ35/Δ41 mosquitoes to fly restricted their escape from aquatic rearing media following eclosion, and substantially reduced adult survival rates. Transgenic strains which contain the EGFP marker gene under the control of strn regulatory regions (0.8 kb, 1.4 kb, and 2.2 kb upstream, respectively), revealed the gene expression pattern of strn in muscle-like tissues in the thorax during late morphogenesis from L4 larvae to young adults. We demonstrated that Ae. aegypti pupae-specific strn is critical for adult mosquito flight capability and a key late-acting lethal target for mosquito-borne disease control.
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Affiliation(s)
- Keun Chae
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA
| | - Collin Valentin
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA
| | - Chanell Dawson
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA
| | - Emma Jakes
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA
| | - Kevin M Myles
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA
| | - Zach N Adelman
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA.
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Meng K, Park SJ, Li LH, Bacon DR, Chen L, Chae K, Park JY, Burnett AD, Linfield EH, Davies AG, Cunningham JE. Tunable broadband terahertz polarizer using graphene-metal hybrid metasurface. Opt Express 2019; 27:33768-33778. [PMID: 31878438 DOI: 10.1364/oe.27.033768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
We demonstrate an electrically tunable polarizer for terahertz (THz) frequency electromagnetic waves formed from a hybrid graphene-metal metasurface. Broadband (>3 THz) polarization-dependent modulation of THz transmission is demonstrated as a function of the graphene conductivity for various wire grid geometries, each tuned by gating using an overlaid ion gel. We show a strong enhancement of modulation (up to ∼17 times) compared to graphene wire grids in the frequency range of 0.2-2.5 THz upon introduction of the metallic elements. Theoretical calculations, considering both plasmonic coupling and Drude absorption, are in good agreement with our experimental findings.
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Chae K, Isaacs CG, Reeves PH, Maloney GS, Muday GK, Nagpal P, Reed JW. Arabidopsis SMALL AUXIN UP RNA63 promotes hypocotyl and stamen filament elongation. Plant J 2012; 71:684-97. [PMID: 22507274 DOI: 10.1111/j.1365-313x.2012.05024.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Auxin regulates plant growth and development in part by activating gene expression. Arabidopsis thaliana SMALL AUXIN UP RNAs (SAURs) are a family of early auxin-responsive genes with unknown functionality. Here, we show that transgenic plant lines expressing artificial microRNA constructs (aMIR-SAUR-A or -B) that target a SAUR subfamily (SAUR61-SAUR68 and SAUR75) had slightly reduced hypocotyl and stamen filament elongation. In contrast, transgenic plants expressing SAUR63:GFP or SAUR63:GUS fusions had long hypocotyls, petals and stamen filaments, suggesting that these protein fusions caused a gain of function. SAUR63:GFP and SAUR63:GUS seedlings also accumulated a higher level of basipetally transported auxin in the hypocotyl than did wild-type seedlings, and had wavy hypocotyls and twisted inflorescence stems. Mutations in auxin efflux carriers could partially suppress some SAUR63:GUS phenotypes. In contrast, SAUR63:HA plants had wild-type elongation and auxin transport. SAUR63:GFP protein had a longer half-life than SAUR63:HA. Fluorescence imaging and microsomal fractionation studies revealed that SAUR63:GFP was localized mainly in the plasma membrane, whereas SAUR63:HA was present in both soluble and membrane fractions. Low light conditions increased SAUR63:HA protein turnover rate. These results indicate that membrane-associated Arabidopsis SAUR63 promotes auxin-stimulated organ elongation.
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Affiliation(s)
- Keun Chae
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
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Abstract
BACKGROUND Pollination is a crucial step in angiosperm (flowering plant) reproduction. Highly orchestrated pollen-pistil interactions and signalling events enable plant species to avoid inbreeding and outcrossing as a species-specific barrier. In compatible pollination, pollen tubes carrying two sperm cells grow through the pistil transmitting tract and are precisely guided to the ovules, discharging the sperm cells to the embryo sac for fertilization. SCOPE In Lilium longiflorum pollination, growing pollen tubes utilize two critical mechanisms, adhesion and chemotropism, for directional growth to the ovules. Among several molecular factors discovered in the past decade, two small, secreted cysteine-rich proteins have been shown to play major roles in pollen tube adhesion and reorientation bioassays: stigma/style cysteine-rich adhesin (SCA, approx. 9·3 kDa) and chemocyanin (approx. 9·8 kDa). SCA, a lipid transfer protein (LTP) secreted from the stylar transmitting tract epidermis, functions in lily pollen tube tip growth as well as in forming the adhesive pectin matrix at the growing pollen tube wall back from the tip. Lily chemocyanin is a plantacyanin family member and acts as a directional cue for reorienting pollen tubes. Recent consecutive studies revealed that Arabidopsis thaliana homologues for SCA and chemocyanin play pivotal roles in tip polarity and directionality of pollen tube growth, respectively. This review outlines the biological roles of various secreted proteins in angiosperm pollination, focusing on plant LTPs and chemocyanin.
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Chae K, Gonong BJ, Kim SC, Kieslich CA, Morikis D, Balasubramanian S, Lord EM. A multifaceted study of stigma/style cysteine-rich adhesin (SCA)-like Arabidopsis lipid transfer proteins (LTPs) suggests diversified roles for these LTPs in plant growth and reproduction. J Exp Bot 2010; 61:4277-90. [PMID: 20667964 PMCID: PMC2955742 DOI: 10.1093/jxb/erq228] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 07/02/2010] [Accepted: 07/06/2010] [Indexed: 05/19/2023]
Abstract
Lily stigma/style cysteine-rich adhesin (SCA), a plant lipid transfer protein (LTP) which is secreted into the extracellular matrix, functions in pollen tube guidance in fertilization. A gain-of-function mutant (ltp5-1) for Arabidopsis LTP5, an SCA-like molecule, was recently shown to display defects in sexual reproduction. In the current study, it is reported that ltp5-1 plants have dwarfed primary shoots, delayed hypocotyl elongation, various abnormal tissue fusions, and display multibranching. These mutant phenotypes in vegetative growth are recessive. No abnormality was found in ltp5-1/+ plants. In a phylogenetic analysis of plant LTPs, SCA-like Arabidopsis LTPs were classified with conventional plant LTPs. Homology modelling-based electrostatic similarity index (ESI) clustering was used to show diversity in spatial distributions of electrostatic potentials of SCA-like LTPs, suggestive of their various roles in interaction in the extracellular matrix space. β-Glucuronidase (GUS) analysis showed that SCA-like Arabidopsis LTP genes are diversely present in various tissues. LTP4 was found specifically in the guard cells and LTP6 in trichomes as well as in other tissues. LTP1 levels were specifically abundant in the stigma, and both LTP3 and LTP6 in the ovules. LTP2 and LTP4 gene levels were up-regulated in whole seedlings with 20% polyethylene glycol (PEG) and 300 mM NaCl treatments, respectively. LTP5 was up-regulated in the hypocotyl with 3 d dark growth conditions. LTP6 was specifically expressed in the tip of the cotyledon under drought stress conditions. The results suggest that SCA-like Arabidopsis LTPs are multifunctional, with diversified roles in plant growth and reproduction.
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Affiliation(s)
- Keun Chae
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
| | - Benedict J. Gonong
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - Seung-Chul Kim
- Department of Biological Sciences, SungKyunKwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
| | - Chris A. Kieslich
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Dimitrios Morikis
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | | | - Elizabeth M. Lord
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
- Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA
- To whom correspondence should be addressed. E-mail:
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12
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Chae K, Kieslich CA, Morikis D, Kim SC, Lord EM. A gain-of-function mutation of Arabidopsis lipid transfer protein 5 disturbs pollen tube tip growth and fertilization. Plant Cell 2009; 21:3902-14. [PMID: 20044438 PMCID: PMC2814499 DOI: 10.1105/tpc.109.070854] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2009] [Revised: 11/11/2009] [Accepted: 11/28/2009] [Indexed: 05/18/2023]
Abstract
During compatible pollination of the angiosperms, pollen tubes grow in the pistil transmitting tract (TT) and are guided to the ovule for fertilization. Lily (Lilium longiflorum) stigma/style Cys-rich adhesin (SCA), a plant lipid transfer protein (LTP), is a small, secreted peptide involved in pollen tube adhesion-mediated guidance. Here, we used a reverse genetic approach to study biological roles of Arabidopsis thaliana LTP5, a SCA-like LTP. The T-DNA insertional gain-of-function mutant plant for LTP5 (ltp5-1) exhibited ballooned pollen tubes, delayed pollen tube growth, and decreased numbers of fertilized eggs. Our reciprocal cross-pollination study revealed that ltp5-1 results in both male and female partial sterility. RT-PCR and beta-glucuronidase analyses showed that LTP5 is present in pollen and the pistil TT in low levels. Pollen-targeted overexpression of either ltp5-1 or wild-type LTP5 resulted in defects in polar tip growth of pollen tubes and thereby decreased seed set, suggesting that mutant ltp5-1 acts as a dominant-active form of wild-type LTP5 in pollen tube growth. The ltp5-1 protein has additional hydrophobic C-terminal sequences, compared with LTP5. In our structural homology/molecular dynamics modeling, Tyr-91 in ltp5-1, replacing Val-91 in LTP5, was predicted to interact with Arg-45 and Tyr-81, which are known to interact with a lipid ligand in maize (Zea mays) LTP. Thus, Arabidopsis LTP5 plays a significant role in reproduction.
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MESH Headings
- Amino Acid Sequence
- Antigens, Plant/genetics
- Antigens, Plant/metabolism
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Arabidopsis/metabolism
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Base Sequence
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- DNA, Bacterial/genetics
- Fertilization/genetics
- Gene Expression Regulation, Plant
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Insertional
- Mutation
- Phylogeny
- Plant Infertility/genetics
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/growth & development
- Plants, Genetically Modified/metabolism
- Pollen Tube/growth & development
- Protein Structure, Tertiary
- RNA, Plant/genetics
- Sequence Alignment
- Sequence Homology, Amino Acid
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Affiliation(s)
- Keun Chae
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
- Center for Plant Cell Biology, University of California, Riverside, California 92521
| | - Chris A. Kieslich
- Department of Bioengineering, University of California, Riverside, California 92521
| | - Dimitrios Morikis
- Center for Plant Cell Biology, University of California, Riverside, California 92521
- Department of Bioengineering, University of California, Riverside, California 92521
| | - Seung-Chul Kim
- Department of Biological Sciences, Sung Kyun Kwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
| | - Elizabeth M. Lord
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
- Center for Plant Cell Biology, University of California, Riverside, California 92521
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13
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Chae K, Zhang K, Zhang L, Morikis D, Kim ST, Mollet JC, de la Rosa N, Tan K, Lord EM. Two SCA (Stigma/Style Cysteine-rich Adhesin) Isoforms Show Structural Differences That Correlate with Their Levels of in Vitro Pollen Tube Adhesion Activity. J Biol Chem 2007; 282:33845-33858. [PMID: 17878166 DOI: 10.1074/jbc.m703997200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lily pollen tubes grow adhering to an extracellular matrix produced by the transmitting tract epidermis in a hollow style. SCA, a small ( approximately 9.4 kDa), basic protein plus low esterified pectin from this extracellular matrix are involved in the pollen tube adhesion event. The mode of action for this adhesion event is unknown. We partially separated three SCA isoforms from the lily stigma in serial size exclusion column fractions (SCA1, 9370 Da; SCA2, 9384 Da; SCA3, 9484 Da). Peptide sequencing analysis allowed us to determine two amino acid variations in SCA3, compared with SCA1. For SCA2, however, there are more sequence variations yet to be identified. Our structural homology and molecular dynamics modeling results show that SCA isoforms have the plant nonspecific lipid transfer protein-like structure: a globular shape of the orthogonal 4-helix bundle architecture, four disulfide bonds, an internal hydrophobic and solvent-inaccessible cavity, and a long C-terminal tail. The Ala(71) in SCA3, replacing the Gly(71) in SCA1, has no predictable effect on structure. The Arg(26) in SCA3, replacing the Gly(26) in SCA1, is predicted to cause structural changes that result in a significantly reduced volume for the internal hydrophobic cavity in SCA3. The volume of the internal cavity fluctuates slightly during the molecular dynamics simulation, but overall, SCA1 displays a larger cavity than SCA3. SCA1 displays higher activity than SCA3 in the in vitro pollen tube adhesion assay. No differences were found between the two SCAs in a binding assay with pectin. The larger size of the hydrophobic cavity in SCA1 correlates with its higher adhesion activity.
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Affiliation(s)
- Keun Chae
- Center for Plant Cell Biology, University of California, Riverside, California, 92521; Department of Botany and Plant Sciences, University of California, Riverside, California, 92521
| | - Kangling Zhang
- Mass Spectrometry Facility, University of California, Riverside, California, 92521
| | - Li Zhang
- Department of Chemistry, University of California, Riverside, California, 92521
| | - Dimitrios Morikis
- Department of Bioengineering, University of California, Riverside, California 92521
| | - Sun Tae Kim
- Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Jean-Claude Mollet
- Laboratoire de Glycobiologie et Transports chez les Végétaux, UMR CNRS 6037, IRFPM 23, Université de Rouen, 76821 Mont Saint-Aignan Cedex, France
| | - Noelle de la Rosa
- Department of Botany and Plant Sciences, University of California, Riverside, California, 92521
| | - Kimberly Tan
- Department of Botany and Plant Sciences, University of California, Riverside, California, 92521
| | - Elizabeth M Lord
- Center for Plant Cell Biology, University of California, Riverside, California, 92521; Department of Botany and Plant Sciences, University of California, Riverside, California, 92521.
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14
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Yu PW, Tabuchi RS, Kato RM, Astrakhan A, Humblet-Baron S, Kipp K, Chae K, Ellmeier W, Witte ON, Rawlings DJ. Sustained correction of B-cell development and function in a murine model of X-linked agammaglobulinemia (XLA) using retroviral-mediated gene transfer. Blood 2004; 104:1281-90. [PMID: 15142874 DOI: 10.1182/blood-2003-09-3044] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Abstract
X-linked agammaglobulinemia (XLA) is a human immunodeficiency caused by mutations in Bruton tyrosine kinase (Btk) and characterized by an arrest in early B-cell development, near absence of serum immunoglobulin, and recurrent bacterial infections. Using Btk- and Tec-deficient mice (BtkTec–/–) as a model for XLA, we determined if Btk gene therapy could correct this disorder. Bone marrow (BM) from 5-fluorouracil (5FU)–treated BtkTec–/– mice was transduced with a retroviral vector expressing human Btk and transplanted into BtkTec–/– recipients. Mice engrafted with transduced hematopoietic cells exhibited rescue of both primary and peripheral B-lineage development, recovery of peritoneal B1 B cells, and correction of serum immunoglobulin M (IgM) and IgG3 levels. Gene transfer also restored T-independent type II immune responses, and B-cell antigen receptor (BCR) proliferative responses. B-cell progenitors derived from Btk-transduced stem cells exhibited higher levels of Btk expression than non-B cells; and marking studies demonstrated a selective advantage for Btk-transduced B-lineage cells. BM derived from primary recipients also rescued Btk-dependent function in secondary hosts that had received a transplant. Together, these data demonstrate that gene transfer into hematopoietic stem cells can reconstitute Btk-dependent B-cell development and function in vivo, and strongly support the feasibility of pursuing Btk gene transfer for XLA.
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Affiliation(s)
- Phyllis W Yu
- Children's Hospital and Regional Medical Center, 307 Westlake Ave North, Suite 300, Seattle, WA 98109, USA
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15
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Su TT, Guo B, Kawakami Y, Sommer K, Chae K, Humphries LA, Kato RM, Kang S, Patrone L, Wall R, Teitell M, Leitges M, Kawakami T, Rawlings DJ. PKC-beta controls I kappa B kinase lipid raft recruitment and activation in response to BCR signaling. Nat Immunol 2002; 3:780-6. [PMID: 12118249 DOI: 10.1038/ni823] [Citation(s) in RCA: 265] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
NF-kappa B signaling is required for the maintenance of normal B lymphocytes, whereas dysregulated NF-kappa B activation contributes to B cell lymphomas. The events that regulate NF-kappa B signaling in B lymphocytes are poorly defined. Here, we demonstrate that PKC-beta is specifically required for B cell receptor (BCR)-mediated NF-kappa B activation. B cells from protein kinase C-beta (PKC-beta)-deficient mice failed to recruit the I kappa B kinase (IKK) complex into lipid rafts, activate IKK, degrade I kappa B or up-regulate NF-kappa B-dependent survival signals. Inhibition of PKC-beta promoted cell death in B lymphomas characterized by exaggerated NF-kappa B activity. Together, these data define an essential role for PKC-beta in BCR survival signaling and highlight PKC-beta as a key therapeutic target for B-lineage malignancies.
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Affiliation(s)
- Thomas T Su
- The Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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16
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Abstract
Age- and strain-associated alterations in intestinal and hepatic antioxidant defense enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST), and lipid peroxidation were examined in Wistar and F344 rats of both strains aged 2 weeks, 2.5, 10 and 23 months. In the small intestine, activities of SOD and GSH-PX and lipid peroxidation were not affected by age or strain difference. Intestinal GST activity was noticeably increased with age in both strains, but somewhat different pattern of age-related changes occurred between two strains. Wistar rats aged 23 months had a significantly higher intestinal GST activity than corresponding age of F344 rats. In the liver, cytosolic SOD activity was not affected by age and strain, whereas GSH-PX and GST activities and lipid peroxidation were markedly influenced by age or strain difference. In particular, hepatic GSH-PX in Wistar rats resulted in a significant increase after 10 months of age and stayed at this level till 23 months of age we examined. Also, Wistar rats showed a higher lipid peroxidation in the liver of 2.5 months old when compared with corresponding age of F344 rats. However, F344 rats did not show any significant age-dependent changes in GSH-PX and lipid peroxidation. In contrast, the GST activity did show much of an age-associated alteration in both strains. Age-associated change in GST activity of Wistar rats was much greater than that observed in F344 rats, especially late in the lifetime (23 months old). It is concluded from our results that age has profound impact on development of some antioxidant enzymes in the small intestine and liver and also strain-related difference in development of antioxidant defense system was observed at least some time of rat life.
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Affiliation(s)
- I Jang
- Department of Animal Science and Biotechnology, Chinju National University 150, Chilam-Dong, Chinju, 660-758, Kyung-Nam, South Korea.
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17
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Sadler BR, Cho SJ, Ishaq KS, Chae K, Korach KS. Three-dimensional quantitative structure-activity relationship study of nonsteroidal estrogen receptor ligands using the comparative molecular field analysis/cross-validated r2-guided region selection approach. J Med Chem 1998; 41:2261-7. [PMID: 9632359 DOI: 10.1021/jm9705521] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A newly developed comparative molecular field analysis (CoMFA) technique, the cross-validated r2-guided region selection (CoMFA/q2-GRS) method, has been used to build a quantitative structure-activity relationship (3D-QSAR) for nonsteroidal estrogen receptor (ER) ligands. Ligands included in this study belong to a series of diethylstilbestrol (DES) and indenestrol analogues whose affinities for the mouse ER (mER) have been determined in our laboratory. The final model utilized 30 compounds and yielded a q2GRS (cross-validated r2, guided region selection) of 0.796, as compared to a q2 of 0.720 for conventional CoMFA, with a standard error of prediction of 0.594 at 3 principal components. This model was used to visualize steric and electrostatic features of the ligands that correspond with ER binding affinity. Results obtained from the CoMFA steric and electrostatic plots of this model have also been compared to information from the ER binding affinities of substituted estradiol analogues. This is in an effort to determine structural features of compounds in the CoMFA analysis that may correspond to those of the estradiol analogues and to further clarify the mode of binding of nonsteroidal ER ligands.
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Affiliation(s)
- B R Sadler
- Laboratory of Reproductive and Developmental Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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18
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Abstract
High-performance liquid chromatography (HPLC) methods have been developed for the separation of substituted indenestrol A and B isomers on different columns. The isomers were separated by normal-phase liquid chromatography with a silica gel column. Enantiomers of these compounds were separated by chiral HPLC and the most successful separations were achieved with a Chiralcel OJ column.
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Affiliation(s)
- B R Sadler
- Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
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19
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Abstract
Diethylstilbestrol (DES) is a well-characterized carcinogen in humans and animals although its mechanisms of carcinogenicity are not yet known. While the estrogenic activity of DES is important, there is evidence that oxidative metabolism also plays an important role for its toxicity. DES is oxidatively metabolized in vivo and in vitro to a number of compounds including diethylstilbestrol-4',4"-quinone (DQ), an unstable and reactive intermediate, and Z,Z-dienestrol (ZZ-DIEN). Estrogen receptor (ER) binding assays with mouse uterine cytosol indicate that DES, DQ and ZZ-DIEN have relative binding affinities of 286, 3.6 and 0.3, respectively, relative to estradiol as 100. In addition, DQ binds irreversibly and specifically to ER suggesting that DQ may be biologically active despite its rapid metabolism and lower binding affinity compared to DES. To test this, COS-1 cells were transfected with an estrogen responsive reporter construct containing of VitA2 estrogen response element (ERE) with or without an ER expression vector. In the presence of ER, treatments with DES, DQ and ZZ-DIEN resulted in 11, 10, and 2-fold induction of chloramphenicol acetyltransferase (CAT) activity, respectively. This induction was mediated by estrogen receptor since it was suppressed by pretreatment with a 10-fold excess of the pure antiestrogen ICI 182,780. These data indicate that DQ is a biologically active intermediate that is capable of transactivation of estrogen responsive genes through the ER. Furthermore, the data suggest that the ability of DQ to irreversibly bind ER may result in persistent stimulation of ER. This persistent stimulation may be related to the carcinogenicity of DES.
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Affiliation(s)
- K Chae
- Receptor Biology Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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20
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Kakuta Y, Pedersen LC, Chae K, Song WC, Leblanc D, London R, Carter CW, Negishi M. Mouse steroid sulfotransferases: substrate specificity and preliminary X-ray crystallographic analysis. Biochem Pharmacol 1998; 55:313-7. [PMID: 9484797 DOI: 10.1016/s0006-2952(97)00465-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Three mouse cytosolic sulfotransferases were expressed in Escherichia coli cells in order to study their substrate specificities toward natural as well as synthetic steroid hormones. The Km and Vmax values confirmed the high substrate specificity of estrogen and hydroxysteroid sulfotransferases toward estradiol and dehydroepiandrosterone, respectively. In sharp contrast, the synthetic estrogen diethylstilbestrol was metabolized efficiently by both enzymes to its disulfate ester. These sulfotransferases display highly stereospecific sulfotransferase activity for sulfating only the trans-isomer of diethylstilbestrol. Crystals suitable for high-resolution structure determination of estrogen sulfotransferase were grown with polyethylene glycol. The crystals belong to the orthorhombic space group P2(1)2(1)2, and diffracted to 2.5 A.
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Affiliation(s)
- Y Kakuta
- Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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21
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Waller CL, Oprea TI, Chae K, Park HK, Korach KS, Laws SC, Wiese TE, Kelce WR, Gray LE. Ligand-based identification of environmental estrogens. Chem Res Toxicol 1996; 9:1240-8. [PMID: 8951225 DOI: 10.1021/tx960054f] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) paradigm, was used to examine the estrogen receptor (ER) binding affinities of a series of structurally diverse natural, synthetic, and environmental chemicals of interest. The CoMFA/3D-QSAR model is statistically robust and internally consistent, and successfully illustrates that the overall steric and electrostatic properties of structurally diverse ligands for the estrogen receptor are both necessary and sufficient to describe the binding affinity. The ability of the model to accurately predict the ER binding affinity of an external test set of molecules suggests that structure-based 3D-QSAR models may be used to supplement the process of endocrine disruptor identification through prioritization of novel compounds for bioassay. The general application of this 3D-QSAR model within a toxicological framework is, at present, limited only by the quantity and quality of biological data for relevant biomarkers of toxicity and hormonal responsiveness.
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Affiliation(s)
- C L Waller
- Experimental Toxicology Divisions, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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22
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Shelby MD, Newbold RR, Tully DB, Chae K, Davis VL. Assessing environmental chemicals for estrogenicity using a combination of in vitro and in vivo assays. Environ Health Perspect 1996; 104:1296-300. [PMID: 9118870 PMCID: PMC1469534 DOI: 10.1289/ehp.961041296] [Citation(s) in RCA: 275] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Because of rampant concern that estrogenic chemicals in the environment may be adversely affecting the health of humans and wildlife, reliable methods for detecting and characterizing estrogenic chemicals are needed. It is important that general agreement be reached on which tests to use and that these tests then be applied to the testing of both man-made and naturally occurring chemicals. As a step toward developing a comprehensive approach to screening chemicals for estrogenic activity, three assays for detecting estrogenicity were conducted on 10 chemicals with known or suspected estrogenic activity. The assays were 1) competitive binding with the mouse uterine estrogen receptor, 2) transcriptional activation in HeLa cells transfected with plasmids containing an estrogen receptor and a response element, and 3) the uterotropic assay in mice. The chemicals studied were 17 beta-estradiol, diethylstilbestrol, tamoxifen, 4-hydroxytamoxifen, methoxychlor, the methoxychlor metabolite 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), endosulfan, nonylphenol, o,p'-DDT, and kepone. These studies were conducted to assess the utility of this three-assay combination in the routine screening of chemicals, or combinations of chemicals, for estrogenic activity. Results were consistent among the three assays with respect to what is known about the estrogenic activities of the chemicals tested and their requirements for metabolic activation. By providing information on three levels of hormonal activity (receptor binding, transcriptional activation, and an in vivo effect in an estrogen-responsive tissue), an informative profile of estrogenic activity is obtained with a reasonable investment of resources.
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Affiliation(s)
- M D Shelby
- Reproductive Toxicology Group, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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23
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Chae K, Gibson MK, Korach KS. Estrogen receptor stereochemistry: ligand binding orientation and influence on biological activity. Mol Pharmacol 1991; 40:806-11. [PMID: 1944245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Racemic (Rac) 4'- and 5-deoxyindenestrol A (4'-DIA and 5-DIA), monohydroxyl analogs of the diethylstilbestrol (DES) oxidative metabolite indenestrol A (IA), were synthesized, and their enantiomers were resolved and isolated. Each compound was then tested for estrogen receptor (ER) binding affinity, uterotropic activity, and nuclear ER levels, to further define the stereochemical preference of the ER and to structually evaluate the function of each IA hydroxyl group for binding and biological activity. Competitive binding to cytosolic ER determined the relative binding affinity of racemic mixtures of 4'- and 5-DIA as 1.3 and 3.7, respectively, compared with that of DES, 286. The ER exhibited a binding preference for the S-enantiomer of both compounds, with relative binding affinities of 4'-DIA-R, 0.2; 4'-DIA-S, 1.8; 5-DIA-R, 0.9; and 5-DIA S, 5.6. 4'-DIA-Rac produced 3 times the in vivo stimulation of 5-DIA-Rac in the uterotropic bioassay (with mouse uterine doubling doses of 302.4 and 800 micrograms/kg, respectively). Nuclear ER levels measured 1 hr after in vivo treatment with either 160 micrograms/kg 4'-DIA or 80 micrograms/kg 5-DIA showed a maximum binding level of 2 (4'-DIA) and 1.5 (5-DIA) times saline control, with these doses producing levels nearly equal to that caused by a 10 micrograms/kg dose of IA. Metabolic studies were carried out by treating mice with [3H]4'- and [3H]5-DIA-Rac, to determine the differential binding affinity and biological stimulation of 4'-DIA and 5-DIA. The in vivo metabolism of the [3H]DIA compounds showed formation of [3H]IA-Rac in urine extracts, as analyzed by chiral high performance liquid chromatography. Furthermore, in vitro incubation of unlabeled 4'- and 5-DIA-Rac with mouse liver microsomes showed stereospecific metabolism, with IA-S primarily formed from 4'-DIA-Rac and IA-R from 5-DIA-Rac. Metabolism of 4'-DIA-Rac to the more active IA S-enantiomer and of 5-DIA-Rac to the less active IA R-enantiomer contributes to the different biological activities, because the ER exhibits a chiral preference for these compounds. The higher binding affinity of 5-DIA indicates that the phenyl ring hydroxyl group is required for high affinity binding; however, both hydroxyl groups are needed for subsequent biological activity. These data further suggest that the ER demonstrates stereochemical ligand binding and that IA binds in an orientation relative to 17 beta-estradiol in which the IA phenyl ring corresponds to the estradiol A-ring.
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Affiliation(s)
- K Chae
- Receptor Biology Section, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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24
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Abstract
Estrogen stimulation of the uterus produces a spectrum of biochemical responses that are customarily linked together. This report is an overview of a series of studies by our laboratory investigating the role of different ligand structures in eliciting hormonal responses. Diethylstilbestrol (DES) and certain structural analogs, indenestrol A (IA), indenestrol B (IB), and pseudo-DES, were used as probes to segregate various genomic responses previously considered interrelated, most notably the events of specific protein synthesis and DNA synthesis. These compounds have weak uterotrophic activity; however, they interact with high affinity specifically with mouse uterine estrogen receptors (ERs). All of them produce stoichiometrically similar amounts of ER complex in the nucleus. Indenestrol A and IB possess a single chiral carbon atom and exist as a mixture of enantiomers (ENTs). Competitive binding assays of pure ENTs and cytosolic ERs demonstrated a stereochemical chiral preference for the IA isomer but not IB. This preference was also evident from nuclear ER occupancy experiments. Biologic activity of the IA ENTs also demonstrated differences as seen by receptor binding. Ornithine decarboxylase (ODC) activity was stimulated 600% by DES and partially by IA (rac). All of the ODC activity produced by IA (rac) was due to the IA(C3)-S ENT. Uterine DNA synthesis was measured after treatment with the IA compounds. Indenestrol A (rac) increased DNA synthesis to 40% of the level seen with DES. The weak ENTs showed no activity and the active ENTs were weaker than the IA racemic. These compounds should be useful probes for studying the individual responses involved in estrogen-induced uterine growth.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K S Korach
- Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709
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25
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Chae K, Johnston SH, Korach KS. Multiple estrogen binding sites in the uterus: stereochemistry of receptor and non-receptor binding of diethylstilbestrol and its metabolites. J Steroid Biochem Mol Biol 1991; 38:35-42. [PMID: 1997122 DOI: 10.1016/0960-0760(91)90398-o] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Indenestrol A (IA), an oxidative metabolite of the synthetic estrogen diethylstilbestrol (DES), has high binding affinity for estrogen receptor in mouse uterine cytosol but possesses weak biological activity. Racemic mixture of optically active [3H]indenestrol A (IA-Rac) was separated and purified into individual enantiomers on a semi-preparative scale by HPLC with a Chiralpak OP(+) column. The structure-activity relationship was investigated among the [3H]IA enantiomers (IA-R and IA-S) and [3H]DES through direct saturation binding assays using mouse uterine cytosol. Specific binding curves and Scatchard plots were obtained for each [3H]ligand; DES, IA-Rac, IA-R and IA-S. IA-S enantiomer (Kd = 0.67) binds to the estrogen receptor with the same affinity as DES (Kd = 0.71) and four times higher affinity than IA-R (Kd = 2.56). The number of binding sites for IA-S is approximately the same as estradiol, DES and IA-Rac while IA-R binds far fewer sites than the other ligands. Saturation binding assays indicated that [3H]DES and [3H]IA enantiomers exhibited a higher level of non-specific binding to the cytosol receptor compared to estradiol which has a low level of non-specific binding. These binding studies led to the detection of an additional binding component for the stilbestrol compounds in estrogen target tissue cytosol preparations. Sucrose density gradient separation assays under low salt conditions showed that both [3H]DES and [3H]IA compounds bound to the 8S form of the receptor, the same as E2. But, in addition both DES and IA bound to another binding component in 4S region. The binding to the 4S component were partially displaced by the addition of excess unlabeled E2 and DES. Further characterization of the 4S component is described.
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Affiliation(s)
- K Chae
- Receptor Biology Section, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
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Korach KS, Chae K, Levy LA, Duax WL, Sarver PJ. Diethylstilbestrol metabolites and analogs. Stereochemical probes for the estrogen receptor binding site. J Biol Chem 1989; 264:5642-7. [PMID: 2925625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Indenestrol A (IA) and indenestrol B (IB) are analogs and metabolites of diethylstilbestrol (DES). These compounds have high binding affinity with the estrogen receptor (ER) but possess weak uterotropic activity. Due to their chemical structures, IA and IB exist as mixtures of enantiomers. We investigated whether the poor biological activity of these compounds was due to differential activity of the enantiomers. We also utilized these compounds as probes to determine the extent of stereochemical sensitivity in the ER ligand binding site. The IA and IB enantiomers were separated to greater than 98% purity using a chiral high pressure liquid chromatography column. Their enantiomeric nature was confirmed by mass spectrometry and NMR. The purified IA enantiomer peak 1 was derivatized with 4-bromobenzoyl chloride. The resulting di(4-bronobenzoate) IA was analyzed by x-ray crystallography and the absolute enantiomeric conformation assigned is C(3)-R. The IA enantiomers designated IA-R and A-S were assayed by competitive binding to cytosolic ER. The competitive binding index was estradiol, 100; DES, 286; IA-Rac (racemic mixture of IA), 143; IA-R, 3; and IA-S, 285; the index showed that ER demonstrates a stereochemical chiral preference. The IB enantiomers did not show a binding preference: IB, 145; IB-1, 100; and IB-2, 143. The differences in the IA enantiomer binding were shown to be due to competitive interactions by Lineweaver-Burk analysis of saturation binding of estradiol to ER in the presence of 1-, 5-, and 10-fold molar excess of competitor. Differences in binding affinity of the enantiomers could be partially explained by differences in the association rate constant (k+1) determined by association rate inhibition studies in which IA-S was 15 times more active than IA-R. Nuclear estrogen receptor levels were measured 1 h after in vivo treatment with doses of 5-20 micrograms/kg. The IA-Rac produced only 60% of the levels is compared with DES. Nuclear ER levels were checked every 30 min up to 2 h with no apparent difference, indicating that the low early levels were not due to a delayed estrogen receptor retention. When the enantiomers were tested individually only a dose of 10 micrograms/kg IA-S translocated ER to a level comparable to DES, while IA-R showed low levels at several doses. These results suggest that the poor biological activity of IA may be related to the differential ER interaction of its enantiomers.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K S Korach
- Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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Affiliation(s)
- K Chae
- Laboratory of Reproductive and Developmental Toxicology, National Institutes of Health, Research Triangle Park, NC 27709
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Chae K, McKinney JD. Molecular complexes of thyroid hormone tyrosyl rings with aromatic donors. Possible relationship to receptor protein interactions. J Med Chem 1988; 31:357-62. [PMID: 2828621 DOI: 10.1021/jm00397a015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Several lines of evidence have indicated that thyroid hormones share common molecular properties (accessible planar face and lateral halogenation) with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds of environmental importance and can modulate their toxicity. Binding of dioxin to a soluble intracellular protein (dioxin or Ah receptor) appears to be the initial step in their mechanism of toxicity and a stacking interaction model has been proposed at the molecular level. It has also been recognized that the Ah receptor and the triiodothyronine nuclear receptor share certain physical and chemical properties important in their binding interactions. In this work, we examined the possibility that thyroid hormones might also be able to bind by a stacking complexation mechanism. By use of methods based on nuclear magnetic resonance spectroscopy, selected, structurally distinct thyroid hormone analogues with widely different hormonal activities were shown to function as electron acceptors in molecular complexes with aromatic donors involving the nonphenolic or tyrosyl ring. Binding free energies for these complexes correlated well with those previously reported for the triiodothyronine (L-T3) nuclear receptor binding interaction with the same compounds. This included preference for L-T3 over thyroxine (L-T4), very favorable binding of 3,5,3'-triiodothyroacetic acid (Triac), and marked preference for L-T3 over D-T3. These results suggest that a considerable part of the structural specificity in thyroid hormone action may be mediated by the tyrosyl ring interaction. Binding ligands for the triiodothyronine nuclear receptor and the Ah receptor may share common molecular parameters in the expression of their binding activities.
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Affiliation(s)
- K Chae
- Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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Korach KS, Sarver P, Chae K, McLachlan JA, McKinney JD. Estrogen receptor-binding activity of polychlorinated hydroxybiphenyls: conformationally restricted structural probes. Mol Pharmacol 1988; 33:120-6. [PMID: 3122017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A series of polychlorinated hydroxybiphenyls (PCBs) has been tested for their binding activity to soluble uterine estrogen receptor protein. Competitive binding analysis was performed on 0-40% ammonium sulfate-enriched uterine cytosol receptor preparations which improved the binding activity for the PCB compounds by a factor of 10-40, by decreasing the nonspecific binding. The binding activities have been correlated to molecular properties supported by molecular modeling studies which emphasize the importance of conformational restriction. The estrogen receptor bound 4-hydroxy-2',4',6'-trichlorobiphenyl (4H2',4',6'TCB) with the greatest affinity, with the concentration of unlabeled inhibitor yielding half-maximal specific binding relative to estradiol (C50) being approximately 42 compared to estradiol, C50 approximately 1.0. PCB compounds that demonstrated appreciable receptor-binding activity were also active in vivo in stimulating uterine weight increases, whereas weak binders were inactive. The 4H2',4',6'TCB compound represents a high degree of conformational restriction around the interring bond due to the presence of two ortho-chlorine atoms. The other PCBs in this series, which show lower receptor-binding activity, vary in position of chlorine substituents and can assume multiple low energy conformations as a result of less hindrance to rotation around the interring bond.
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Affiliation(s)
- K S Korach
- Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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McKinney J, Fannin R, Jordan S, Chae K, Rickenbacher U, Pedersen L. Polychlorinated biphenyls and related compound interactions with specific binding sites for thyroxine in rat liver nuclear extracts. J Med Chem 1987; 30:79-86. [PMID: 3100800 DOI: 10.1021/jm00384a014] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Thyroid hormone analogues, polychlorinated biphenyls (PCBs), and their derivatives were shown to bind specifically to thyroxine-specific binding sites in rat liver nuclear extracts. The structure-binding relationship for thyroxine binding prealbumin was qualitatively similar to that for the nuclear receptor. In general for both binding proteins, increased binding affinity was seen for the more linear and in some cases rectangular shaped (as opposed to the angular shaped thyroid hormones) chlorinated aromatic hydrocarbons with chlorine concentrated in lateral positions (3,3',5,5'-substitution on biphenyl nucleus). However two groups of compounds showed distinct quantitative differences. The relatively less polar and more lipophilic nonhydroxylated PCBs bound the nuclear receptor with significantly lower affinities while two compounds that are structurally related by the potential for equilibrium interconversion to a rigid planar structure bound with significantly higher affinities. This latter class of compounds represents soluble dioxin (TCDD) approximate isosteres and has an extended (polarizable) pi-system brought about by a planar structure (or conversion to the same) and lateral halogenation. These structure requirements are maximally expressed in 3,3',5,5'-tetrachlorodiphenoquinone (TCDQ), which shows a remarkably high affinity (Ka = 1.84 X 10(11) M-1) for the nuclear receptor. Thus, the nuclear receptor shows the expected structural specificity and sensitivity for possible involvement in the high toxicity of these classes of compounds. The physiological significance of these binding results is supported by the dose-dependent regulation (increase) of the thyroxine nuclear receptor number by dioxin, although the mechanism responsible for this increase is not clear. The nuclear binding component was further analyzed by sucrose density gradient centrifugation and was found to have a sedimentation coefficient of 4.3 S under high salt conditions. A crude estimate of the molecular weight (45,200) was obtained from a linear plot of standard globular protein fraction number (sedimentation coefficient) vs. log molecular weight. Although direct evidence is not provided, the thyroxine nuclear receptor may cooperate with a second receptor in binding the TCDQ type ligand or exists as a multimeric species with binding properties of both prealbumin and the dioxin (or Ah) receptor.
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McKinney JD, Fawkes J, Jordan S, Chae K, Oatley S, Coleman RE, Briner W. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) as a potent and persistent thyroxine agonist: a mechanistic model for toxicity based on molecular reactivity. Environ Health Perspect 1985; 61:41-53. [PMID: 2998749 PMCID: PMC1568759 DOI: 10.1289/ehp.856141] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
TCDD and thyroxine have common molecular reactivity properties which enable them to present a planar face and lateral halogens in interactions with proteins. These molecular properties are consistent with the structure-toxicity relationship for TCDD and related compounds. Biological evidence is discussed including preliminary studies on the effects of TCDD exposure on tadpole growth and development which is consistent with the possible thyroxine-like activity of TCDD. The work suggests the possibility that toxicity is at least in part the expression of potent and persistent thyroid hormone activity (responses induced by TCDD which qualitatively correspond to those mediated by thyroid hormones). A mechanism for toxicity is proposed which involves receptor proteins; the planar aromatic system controls binding to cytosolic proteins and halogen substituents regulate binding to nuclear proteins. This simple model based on molecular reactivity sheds light on the diversified effects of TCDD and related compound toxicity and on certain thyroid hormone action. The model also permits predictions to be made with regard to the toxicity and thyroid hormone activity of untested compounds. In addition, the model suggests a general mechanism for hormone action based on metabolically regulated differential and cooperative protein receptor binding events in cellular compartments which can explain agonism, antagonism and potentiation within the framework of receptor occupancy theory.
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McKinney JD, Chae K, McConnell EE, Birnbaum LS. Structure-induction versus structure-toxicity relationships for polychlorinated biphenyls and related aromatic hydrocarbons. Environ Health Perspect 1985; 60:57-68. [PMID: 2992928 PMCID: PMC1568558 DOI: 10.1289/ehp.856057] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A comparison of the structure-induction (involving rat and mouse Ah receptor binding) and structure-toxicity (in vivo guinea pig toxicity) relationships suggests that two receptors with structurally distinct binding properties may be involved. This is supported by demonstration of potentiated toxicity through a mechanism believed to involve the Ah receptor as a site of loss with respect to toxicity. Theoretical and working models are proposed for these separate receptors to aid in the search for other relevant binding proteins. The findings suggest that polychlorinated biphenyls that are relatively low in toxicity may have modulating properties on the action of highly toxic compounds with which they are normally found in the environment.
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McKinney JD, Chae K, Oatley SJ, Blake CC. Molecular interactions of toxic chlorinated dibenzo-p-dioxins and dibenzofurans with thyroxine binding prealbumin. J Med Chem 1985; 28:375-81. [PMID: 3919186 DOI: 10.1021/jm00381a018] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The interactions of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds with prealbumin, a model for the nuclear thyroid hormone receptor, have been studied with use of computer graphics and predictions made regarding relative binding affinities for such structures. These modeling predictions were tested by experimentally measuring the binding affinities of dioxin and furan analogues. The results were in general agreement with the modeling predictions and demonstrated that such compounds could be effective competitive binding ligands for thyroxine-specific binding sites in prealbumin. The computer modeling work also demonstrates the importance of lateral chlorine substitution in the binding of these toxic compounds. The prealbumin interaction model should be of use in investigating the structure-toxicity relationships of these classes of toxic compounds. Thus, if prealbumin is a model for the nuclear thyroid hormone receptor, this work would also have major implications bearing on the mechanism of dioxin toxicity and the potential of these compounds to function as potent and persistent thyroxine agonists. A new cooperative receptor mechanism for dioxin toxic action is proposed.
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Albro PW, Chae K, Philpot R, Corbett JT, Schroeder J, Jordan S. In vitro metabolism of mono-2-ethylhexyl phthalate by microsomal enzymes. Similarity to omega- and (omega-1) oxidation of fatty acids. Drug Metab Dispos 1984; 12:742-8. [PMID: 6150824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Mono-2-ethylhexyl pthalate (MEHP) is oxidized to omega-, omega-1-, and omega-2-hydroxylation products as well as (very slightly) to a dicarboxylic acid by washed microsomes from rat liver and kidney, and rabbit but not rat lung. The reactions involve molecular oxygen, are strongly inhibited by carbon monoxide and oxidized cytochrome c, and NADPH is preferred over NADH. Piperonyl butoxide inhibits hydroxylation of MEHP, but clofibrate does not. The differential effects of inducers (phenobarbital and clofibrate) and inhibitors (sodium laurate, n-decane, metyrapone) on terminal and subterminal hydroxylation as well as differences in apparent Km for the two suggest that rat liver contains at least two different MEHP hydroxylases. Comparisons of tissue distribution, susceptibility to inhibitors, and induction properties suggest that the hydroxylation of MEHP is more likely to be mediated by the P-450 isozymes associated with omega- and (omega-1)-hydroxylation of fatty acids than with those that utilize hydrocarbons as substrates.
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Chu CK, Wander JD, Tackett RL, Iturrian WB, Schmitz JP, Garner GE, Chae K. A novel serotonin antagonist 2,2′-bis[3-(2-N,N-dimethylaminoethyl)indolyl]sulfide (BDIS). J Heterocycl Chem 1984. [DOI: 10.1002/jhet.5570210664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Chae K, Albro PW, Luster MI, McKinney JD. A screening assay for the tetrachlorodibenzo-p-dioxin receptor using the [125I]iodovaleramide derivative of trichlorodibenzo-p-dioxin as the binding ligand. Int J Environ Anal Chem 1984; 17:267-274. [PMID: 6086542 DOI: 10.1080/03067318408076978] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A relatively simple assay method for the putative cytosolic 'receptor' that binds 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds is described. The assay is based on specific binding of [125I]dioxin to cytosol 'receptor' protein. Saturation is ensured by competition experiments in which unlabeled TCDD and other competitors displace the radiolabeled ligand from specific binding sites. This assay has been applied to estimation of levels of 'receptor' in cytosol.
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Corbett J, Albro PW, Chae K, Jordan S. The relationship between metabolism of 2,3,4,5,3',4',5'-heptachlorobiphenyl and its ability to induce both cytochromes P-448 and P-450. Chem Biol Interact 1982; 39:331-8. [PMID: 6804101 DOI: 10.1016/0009-2797(82)90049-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Male CD rats received i.p. injections of 2,3,4,5,3',4',5'-heptachlorobiphenyl (7CB) under conditions resulting in induction of both benzphetamine demethylase (cytochrome P-450-dependent) and ethoxyresorufin deethylase (cytochrome P-448-dependent) activities. To test the possibility that one class of induction (P-450) was due to the parent compound and the other (P-448) to a metabolite, liver, adipose, bile, urine and feces were analyzed for the presence of 3,4,5,3',4',5'-hexachlorobiphenyl (6CB) (the major photolysis product of 7CB) and/or 3-hydroxy-3,4,5,3',4',5'-hexachlorobiphenyl (OH-6CB), another known P-448 inducer. To allow for the possibility that 6CB might be a transient intermediate. The results supported the hypothesis that 7CB is a true 'mixed inducer', nor requiring metabolic alteration for its dual activity.
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Chae K, Albro PW, McKinney JD. A new synthesis of tetrachlorofluorodibenzo-p-dioxin. J Environ Sci Health B 1982; 17:441-445. [PMID: 7175095 DOI: 10.1080/03601238209372333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The 1,2,3,4-tetrachloro-7-fluorodibenzo-p-dioxin has been synthesized via condensation of 4-fluorocatechol and pentachloronitrobenzene. This compound could be used as an internal standard for the analysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin by chromatographic methods.
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Luster MI, Albro PW, Chae K, Lawson LD, Corbett JT, McKinney JD. Radioimmunoassay for quantitation of 2,3,7,8-tetrachlorodibenzofuran. Anal Chem 1980; 52:1497-500. [PMID: 6774628 DOI: 10.1021/ac50059a026] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Luster MI, Albro PW, Clark G, Chae K, Chaudhary SK, Lawson LD, Corbett JT, McKinney JD. Production and characterization of antisera specific for chlorinated biphenyl species: initiation of a radioimmunoassay for Aroclors. Toxicol Appl Pharmacol 1979; 50:147-55. [PMID: 115114 DOI: 10.1016/0041-008x(79)90502-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Albro PW, Luster MI, Chae K, Chaudhary SK, Clark G, Lawson LD, Corbett JT, McKinney JD. A radioimmunoassay for chlorinated dibenzo-p-dioxins. Toxicol Appl Pharmacol 1979; 50:137-46. [PMID: 386569 DOI: 10.1016/0041-008x(79)90501-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Luster MI, Albro PW, Chae K, Clark G, McKinney JD. Radioimmunoassay for mono-(2-ethylhexyl) phthalate in unextracted plasma. Clin Chem 1978; 24:429-32. [PMID: 630703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We report a radioimmunoassay for mono-(2-ethylhexyl) phthalate that has been coupled to a protein carrier as a radioligand. Competitive interference tests with a variety of related compounds indicated the assay to be highly specific. Quantitative comparison of mono-(2-ethylhexyl) phthalate values in plasma and serum samples between the radioimmunoassay and gas chromatographic procedures indicated a high reliability. Because this potentially toxic compound can leach into plasma from polyvinyl plastics, this assay should be particularly useful for those involved in the manufacture or use of medical devices made of them.
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Abstract
Abstract
We report a radioimmunoassay for mono-(2-ethylhexyl) phthalate that has been coupled to a protein carrier as a radioligand. Competitive interference tests with a variety of related compounds indicated the assay to be highly specific. Quantitative comparison of mono-(2-ethylhexyl) phthalate values in plasma and serum samples between the radioimmunoassay and gas chromatographic procedures indicated a high reliability. Because this potentially toxic compound can leach into plasma from polyvinyl plastics, this assay should be particularly useful for those involved in the manufacture or use of medical devices made of them.
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McKinney JD, Chae K, Gupta BN, Moore JA, Goldstein HA. Toxicological assessment of hexachlorobiphenyl isomers and 2,3,7,8 tetrachlorodibenzofuran in chicks. I. Relationship of chemical parameters. Toxicol Appl Pharmacol 1976; 36:65-80. [PMID: 818741 DOI: 10.1016/0041-008x(76)90027-2] [Citation(s) in RCA: 124] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Chae K, Piantadosi C, Snyder F. Reductase, phosphatase, and kinase activities in the metabolism of alkyldihydroxyacetone phosphate and alkyldihydroxyacetone. J Biol Chem 1973; 248:6718-23. [PMID: 4147653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Chae K, Piantadosi C, Snyder F. An alternate enzymic route for the synthesis of the alkyl analog of phosphatidic acid involving alkylglycerol. Biochem Biophys Res Commun 1973; 51:119-24. [PMID: 4349319 DOI: 10.1016/0006-291x(73)90516-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Piantadosi C, Chae K, Ishaq KS, Snyder F. Chemical synthesis of 1- 14 C-octadecyldihydroxyacetone phosphate and 1- 14 C-octadecyldihydroxyacetone. J Pharm Sci 1973; 62:320-2. [PMID: 4686414 DOI: 10.1002/jps.2600620232] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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