1
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Chen S, Podolec R, Arongaus AB, Fuchs C, Loubéry S, Demarsy E, Ulm R. Functional divergence of Arabidopsis REPRESSOR OF UV-B PHOTOMORPHOGENESIS 1 and 2 in repression of flowering. Plant Physiol 2024; 194:1563-1576. [PMID: 37956407 PMCID: PMC10904346 DOI: 10.1093/plphys/kiad606] [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] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/27/2023] [Accepted: 10/19/2023] [Indexed: 11/15/2023]
Abstract
Photoperiodic plants coordinate the timing of flowering with seasonal light cues, thereby optimizing their sexual reproductive success. The WD40-repeat protein REPRESSOR OF UV-B PHOTOMORPHOGENESIS 2 (RUP2) functions as a potent repressor of UV RESISTANCE LOCUS 8 (UVR8) photoreceptor-mediated UV-B induction of flowering under noninductive, short-day conditions in Arabidopsis (Arabidopsis thaliana); however, in contrast, the closely related RUP1 seems to play no major role. Here, analysis of chimeric ProRUP1:RUP2 and ProRUP2:RUP1 expression lines suggested that the distinct functions of RUP1 and RUP2 in repressing flowering are due to differences in both their coding and regulatory DNA sequences. Artificial altered expression using tissue-specific promoters indicated that RUP2 functions in repressing flowering when expressed in mesophyll and phloem companion cells, whereas RUP1 functions only when expressed in phloem companion cells. Endogenous RUP1 expression in vascular tissue was quantified as lower than that of RUP2, likely underlying the functional difference between RUP1 and RUP2 in repressing flowering. Taken together, our findings highlight the importance of phloem vasculature expression of RUP2 in repressing flowering under short days and identify a basis for the functional divergence of Arabidopsis RUP1 and RUP2 in regulating flowering time.
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Affiliation(s)
- Song Chen
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Roman Podolec
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva 1211, Switzerland
| | - Adriana B Arongaus
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Christelle Fuchs
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Sylvain Loubéry
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Emilie Demarsy
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Roman Ulm
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva 1211, Switzerland
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2
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Stockenhuber R, Akiyama R, Tissot N, Milosavljevic S, Yamazaki M, Wyler M, Arongaus AB, Podolec R, Sato Y, Widmer A, Ulm R, Shimizu KK. UV RESISTANCE LOCUS 8-Mediated UV-B Response Is Required Alongside CRYPTOCHROME 1 for Plant Survival in Sunlight under Field Conditions. Plant Cell Physiol 2024; 65:35-48. [PMID: 37757822 PMCID: PMC10799719 DOI: 10.1093/pcp/pcad113] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 09/19/2023] [Accepted: 09/26/2023] [Indexed: 09/29/2023]
Abstract
As sessile, photoautotrophic organisms, plants are subjected to fluctuating sunlight that includes potentially detrimental ultraviolet-B (UV-B) radiation. Experiments under controlled conditions have shown that the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8) controls acclimation and tolerance to UV-B in Arabidopsis thaliana; however, its long-term impact on plant fitness under naturally fluctuating environments remain poorly understood. Here, we quantified the survival and reproduction of different Arabidopsis mutant genotypes under diverse field and laboratory conditions. We found that uvr8 mutants produced more fruits than wild type when grown in growth chambers under artificial low-UV-B conditions but not under natural field conditions, indicating a fitness cost in the absence of UV-B stress. Importantly, independent double mutants of UVR8 and the blue light photoreceptor gene CRYPTOCHROME 1 (CRY1) in two genetic backgrounds showed a drastic reduction in fitness in the field. Experiments with UV-B attenuation in the field and with supplemental UV-B in growth chambers demonstrated that UV-B caused the cry1 uvr8 conditional lethal phenotype. Using RNA-seq data of field-grown single and double mutants, we explicitly identified genes showing significant statistical interaction of UVR8 and CRY1 mutations in the presence of UV-B in the field. They were enriched in Gene Ontology categories related to oxidative stress, photoprotection and DNA damage repair in addition to UV-B response. Our study demonstrates the functional importance of the UVR8-mediated response across life stages in natura, which is partially redundant with that of cry1. Moreover, these data provide an integral picture of gene expression associated with plant responses under field conditions.
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Affiliation(s)
- Reinhold Stockenhuber
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Reiko Akiyama
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Nicolas Tissot
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, 30 Quai E. Ansermet, Geneva 1211, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva 1211, Switzerland
| | - Stefan Milosavljevic
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- SIB Swiss Institute of Bioinformatics, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Misako Yamazaki
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Michele Wyler
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Department of Plant and Microbial Biology, University of Zurich, Zollikerstrasse 107, Zurich 8008, Switzerland
| | - Adriana B Arongaus
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, 30 Quai E. Ansermet, Geneva 1211, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva 1211, Switzerland
| | - Roman Podolec
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, 30 Quai E. Ansermet, Geneva 1211, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva 1211, Switzerland
| | - Yasuhiro Sato
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Alex Widmer
- Institute of Integrative Biology, ETH Zurich, Universitätstrasse 16, Zurich 8092, Switzerland
| | - Roman Ulm
- Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, 30 Quai E. Ansermet, Geneva 1211, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva 1211, Switzerland
| | - Kentaro K Shimizu
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
- Kihara Institute for Biological Research, Yokohama City University, 641-12 Maioka, Totsuka-ward, Yokohama 244-0813, Japan
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3
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Fang F, Lin L, Zhang Q, Lu M, Skvortsova MY, Podolec R, Zhang Q, Pi J, Zhang C, Ulm R, Yin R. Mechanisms of UV-B light-induced photoreceptor UVR8 nuclear localization dynamics. New Phytol 2022; 236:1824-1837. [PMID: 36089828 PMCID: PMC9825989 DOI: 10.1111/nph.18468] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
Light regulates the subcellular localization of plant photoreceptors, a key step in light signaling. Ultraviolet-B radiation (UV-B) induces the plant photoreceptor UV RESISTANCE LOCUS 8 (UVR8) nuclear accumulation, where it regulates photomorphogenesis. However, the molecular mechanism for the UV-B-regulated UVR8 nuclear localization dynamics is unknown. With fluorescence recovery after photobleaching (FRAP), cell fractionation followed by immunoblotting and co-immunoprecipitation (Co-IP) assays we tested the function of UVR8-interacting proteins including CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), REPRESSOR OF UV-B PHOTOMORPHOGENESIS 1 (RUP1) and RUP2 in the regulation of UVR8 nuclear dynamics in Arabidopsis thaliana. We showed that UV-B-induced rapid UVR8 nuclear translocation is independent of COP1, which previously was shown to be required for UV-B-induced UVR8 nuclear accumulation. Instead, we provide evidence that the UV-B-induced UVR8 homodimer-to-monomer photo-switch and the concurrent size reduction of UVR8 enables its monomer nuclear translocation, most likely via free diffusion. Nuclear COP1 interacts with UV-B-activated UVR8 monomer, thereby promoting UVR8 nuclear retention. Conversely, RUP1and RUP2, whose expressions are induced by UV-B, inhibit UVR8 nuclear retention via attenuating the UVR8-COP1 interaction, allowing UVR8 to exit the nucleus. Collectively, our data suggest that UV-B-induced monomerization of UVR8 promotes its nuclear translocation via free diffusion. In the nucleus, COP1 binding promotes UVR8 monomer nuclear retention, which is counterbalanced by the major negative regulators RUP1 and RUP2.
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Affiliation(s)
- Fang Fang
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
| | - Li Lin
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
- Key Laboratory of Urban Agriculture Ministry of AgricultureShanghai Jiao Tong UniversityShanghai200240China
- Joint Center for Single Cell BiologyShanghai Jiao Tong UniversityShanghai200240China
| | - Qianwen Zhang
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
| | - Min Lu
- Department of Orthopaedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases, Shanghai Institute of Traumatology and Orthopaedics, Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghai200025China
| | - Mariya Y. Skvortsova
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
| | - Roman Podolec
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3)University of GenevaCH‐1211Geneva 4Switzerland
| | - Qinyun Zhang
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
| | - Jiahao Pi
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
| | - Chunli Zhang
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3)University of GenevaCH‐1211Geneva 4Switzerland
| | - Ruohe Yin
- School of Agriculture and BiologyShanghai Jiao Tong University800 Dongchuan Road, Minhang DistrictShanghai200240China
- Key Laboratory of Urban Agriculture Ministry of AgricultureShanghai Jiao Tong UniversityShanghai200240China
- Joint Center for Single Cell BiologyShanghai Jiao Tong UniversityShanghai200240China
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4
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Podolec R, Wagnon TB, Leonardelli M, Johansson H, Ulm R. Arabidopsis B-box transcription factors BBX20-22 promote UVR8 photoreceptor-mediated UV-B responses. Plant J 2022; 111:422-439. [PMID: 35555928 PMCID: PMC9541035 DOI: 10.1111/tpj.15806] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/26/2022] [Accepted: 05/10/2022] [Indexed: 06/01/2023]
Abstract
Plants undergo photomorphogenic development in the presence of light. Photomorphogenesis is repressed by the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), which binds to substrates through their valine-proline (VP) motifs. The UV RESISTANCE LOCUS 8 (UVR8) photoreceptor senses UV-B and inhibits COP1 through the cooperative binding of its own VP motif and photosensing core to COP1, thereby preventing COP1 binding to substrates, including the basic leucine zipper (bZIP) transcriptional regulator ELONGATED HYPOCOTYL 5 (HY5). As a key promoter of visible light and UV-B photomorphogenesis, HY5 requires coregulators for its function. The B-box family transcription factors BBX20-BBX22 were recently described as HY5 rate-limiting coactivators under red light, but their role in UVR8 signaling was unknown. Here we describe a hypermorphic bbx21-3D mutant with enhanced photomorphogenesis, carrying a proline-to-leucine mutation at position 314 in the VP motif that impairs the interaction with and regulation by COP1. We show that BBX21 and BBX22 are UVR8-dependently stabilized after UV-B exposure, which is counteracted by a repressor induced by HY5/BBX activity. bbx20 bbx21 bbx22 mutants under UV-B are impaired in hypocotyl growth inhibition, photoprotective pigment accumulation and the expression of several HY5-dependent genes under continuous UV-B, but the immediate induction of marker genes after exposure to UV-B remains surprisingly rather unaffected. We conclude that BBX20-BBX22 contribute to HY5 activity in a subset of UV-B responses, but that additional, presently unknown, coactivators for HY5 are functional in early UVR8 signaling.
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Affiliation(s)
- Roman Podolec
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3)University of GenevaGenevaSwitzerland
| | - Timothée B. Wagnon
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
| | - Manuela Leonardelli
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
| | - Henrik Johansson
- Institute of Biology/Applied GeneticsDahlem Centre of Plant Sciences (DCPS), Freie Universität BerlinBerlinGermany
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of SciencesUniversity of GenevaCH‐1211Geneva 4Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3)University of GenevaGenevaSwitzerland
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5
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Ayatollahi Z, Kazanaviciute V, Shubchynskyy V, Kvederaviciute K, Schwanninger M, Rozhon W, Stumpe M, Mauch F, Bartels S, Ulm R, Balazadeh S, Mueller-Roeber B, Meskiene I, Schweighofer A. Dual control of MAPK activities by AP2C1 and MKP1 MAPK phosphatases regulates defence responses in Arabidopsis. J Exp Bot 2022; 73:2369-2384. [PMID: 35088853 PMCID: PMC9015810 DOI: 10.1093/jxb/erac018] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
Mitogen-activated protein kinase (MAPK) cascades transmit environmental signals and induce stress and defence responses in plants. These signalling cascades are negatively controlled by specific Ser/Thr protein phosphatases of the type 2C (PP2C) and dual-specificity phosphatase (DSP) families that inactivate stress-induced MAPKs; however, the interplay between phosphatases of these different types has remained unknown. This work reveals that different Arabidopsis MAPK phosphatases, the PP2C-type AP2C1 and the DSP-type MKP1, exhibit both specific and overlapping functions in plant stress responses. Each single mutant, ap2c1 and mkp1, and the ap2c1 mkp1 double mutant displayed enhanced stress-induced activation of the MAPKs MPK3, MPK4, and MPK6, as well as induction of a set of transcription factors. Moreover, ap2c1 mkp1 double mutants showed an autoimmune-like response, associated with increased levels of the stress hormones salicylic acid and ethylene, and of the phytoalexin camalexin. This phenotype was reduced in the ap2c1 mkp1 mpk3 and ap2c1 mkp1 mpk6 triple mutants, suggesting that the autoimmune-like response is due to MAPK misregulation. We conclude that the evolutionarily distant MAPK phosphatases AP2C1 and MKP1 contribute crucially to the tight control of MAPK activities, ensuring appropriately balanced stress signalling and suppression of autoimmune-like responses during plant growth and development.
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Affiliation(s)
- Zahra Ayatollahi
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Vaiva Kazanaviciute
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Volodymyr Shubchynskyy
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Kotryna Kvederaviciute
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Manfred Schwanninger
- Department of Chemistry, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Wilfried Rozhon
- Department of Agriculture, Ecotrophology, and Landscape Development, Anhalt University of Applied Sciences, Strenzfelder Allee 28, D-06406 Bernburg, Germany
| | - Michael Stumpe
- Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Felix Mauch
- Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Sebastian Bartels
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestraße 1, D-79104 Freiburg, Germany
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 30 Quai E. Ansermet, CH-1211 Geneva, Switzerland
| | - Salma Balazadeh
- Max-Planck-Institute of Molecular Plant Physiology (MPIMP), Am Mühlenberg 1, D-14476 Potsdam, Germany
- University of Potsdam, Karl-Liebknecht-Straße 24, D-14476 Potsdam, Germany
- Institute of Biology Leiden (IBL), Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Bernd Mueller-Roeber
- Max-Planck-Institute of Molecular Plant Physiology (MPIMP), Am Mühlenberg 1, D-14476 Potsdam, Germany
- University of Potsdam, Karl-Liebknecht-Straße 24, D-14476 Potsdam, Germany
- Center of Plant Systems Biology and Biotechnology (CPSBB), Ruski 139 Blvd., Plovdiv 4000, Bulgaria
| | - Irute Meskiene
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
- Department of Functional and Evolutionary Ecology, University of Vienna, Djerassiplatz 1, A-1030 Vienna, Austria
| | - Alois Schweighofer
- Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr.-Bohr-Gasse 9, A-1030 Vienna, Austria
- Department of Functional and Evolutionary Ecology, University of Vienna, Djerassiplatz 1, A-1030 Vienna, Austria
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6
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Abstract
Ultraviolet-B (UV-B) radiation is an intrinsic fraction of sunlight that plants perceive through the UVR8 photoreceptor. UVR8 is a homodimer in its ground state that monomerizes upon UV-B photon absorption via distinct tryptophan residues. Monomeric UVR8 competitively binds to the substrate binding site of COP1, thus inhibiting its E3 ubiquitin ligase activity against target proteins, which include transcriptional regulators such as HY5. The UVR8-COP1 interaction also leads to the destabilization of PIF bHLH factor family members. Additionally, UVR8 directly interacts with and inhibits the DNA binding of a different set of transcription factors. Each of these UVR8 signaling mechanisms initiates nuclear gene expression changes leading to UV-B-induced photomorphogenesis and acclimation. The two WD40-repeat proteins RUP1 and RUP2 provide negative feedback regulation and inactivate UVR8 by facilitating redimerization. Here, we review the molecular mechanisms of the UVR8 pathway from UV-B perception and signal transduction to gene expression changes and physiological UV-B responses.
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Affiliation(s)
- Roman Podolec
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva, Switzerland; , ,
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 1211 Geneva, Switzerland
| | - Emilie Demarsy
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva, Switzerland; , ,
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva, Switzerland; , ,
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 1211 Geneva, Switzerland
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7
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Tavridou E, Schmid-Siegert E, Fankhauser C, Ulm R. UVR8-mediated inhibition of shade avoidance involves HFR1 stabilization in Arabidopsis. PLoS Genet 2020; 16:e1008797. [PMID: 32392219 PMCID: PMC7241853 DOI: 10.1371/journal.pgen.1008797] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [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: 01/07/2020] [Revised: 05/21/2020] [Accepted: 04/26/2020] [Indexed: 11/19/2022] Open
Abstract
Sun-loving plants perceive the proximity of potential light-competing neighboring plants as a reduction in the red:far-red ratio (R:FR), which elicits a suite of responses called the "shade avoidance syndrome" (SAS). Changes in R:FR are primarily perceived by phytochrome B (phyB), whereas UV-B perceived by UV RESISTANCE LOCUS 8 (UVR8) elicits opposing responses to provide a counterbalance to SAS, including reduced shade-induced hypocotyl and petiole elongation. Here we show at the genome-wide level that UVR8 broadly suppresses shade-induced gene expression. A subset of this gene regulation is dependent on the UVR8-stabilized atypical bHLH transcription regulator LONG HYPOCOTYL IN FAR-RED 1 (HFR1), which functions in part redundantly with PHYTOCHROME INTERACTING FACTOR 3-LIKE 1 (PIL1). In parallel, UVR8 signaling decreases protein levels of the key positive regulators of SAS, namely the bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5, in a COP1-dependent but HFR1-independent manner. We propose that UV-B antagonizes SAS via two mechanisms: degradation of PIF4 and PIF5, and HFR1- and PIL1-mediated inhibition of PIF4 and PIF5 function. This work highlights the importance of typical and atypical bHLH transcription regulators for the integration of light signals from different photoreceptors and provides further mechanistic insight into the crosstalk of UVR8 signaling and SAS.
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Affiliation(s)
- Eleni Tavridou
- Department of Botany and Plant Biology, Section of Biology, Faculty of Science, University of Geneva, CH, Geneva, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Emanuel Schmid-Siegert
- SIB-Swiss Institute of Bioinformatics, University of Lausanne, CH, Lausanne, Switzerland
| | - Christian Fankhauser
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH, Lausanne, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Science, University of Geneva, CH, Geneva, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
- * E-mail:
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8
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Tavridou E, Pireyre M, Ulm R. Degradation of the transcription factors PIF4 and PIF5 under UV-B promotes UVR8-mediated inhibition of hypocotyl growth in Arabidopsis. Plant J 2020; 101:507-517. [PMID: 31571300 PMCID: PMC7027837 DOI: 10.1111/tpj.14556] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 09/17/2019] [Accepted: 09/23/2019] [Indexed: 05/03/2023]
Abstract
Inhibition of hypocotyl growth is a well-established UV-B-induced photomorphogenic response that is mediated by the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, the molecular mechanism by which UVR8 signaling triggers inhibition of hypocotyl growth is poorly understood. The bZIP protein ELONGATED HYPOCOTYL 5 (HY5) functions as the main positive regulatory transcription factor in the UVR8 signaling pathway, with HY5-HOMOLOG (HYH) playing a minor role. However, here we demonstrate that hy5 hyh double mutants maintain significant UVR8-dependent hypocotyl growth inhibition. We identify UVR8-dependent inhibition of the activities of bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5 as part of the UVR8 signaling pathway, which results in inhibition of hypocotyl growth. The UVR8-mediated repression of several hypocotyl elongation-related genes is independent of HY5 and HYH but largely associated with UVR8-dependent degradation of PIF4 and PIF5, a process that consequently diminishes PIF4/5 target promoter occupancy. Taken together, our data indicate that UVR8-mediated inhibition of hypocotyl growth involves degradation of PIF4 and PIF5. These findings contribute to our mechanistic understanding of UVR8-induced photomorphogenesis and further support the function of PIFs as integrators of different photoreceptor signaling pathways.
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Affiliation(s)
- Eleni Tavridou
- Department of Botany and Plant BiologySection of BiologyFaculty of ScienceUniversity of GenevaCH‐1211Geneva 4Switzerland
| | - Marie Pireyre
- Department of Botany and Plant BiologySection of BiologyFaculty of ScienceUniversity of GenevaCH‐1211Geneva 4Switzerland
| | - Roman Ulm
- Department of Botany and Plant BiologySection of BiologyFaculty of ScienceUniversity of GenevaCH‐1211Geneva 4Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3)University of GenevaCH-1211Geneva 4Switzerland
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9
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Lau K, Podolec R, Chappuis R, Ulm R, Hothorn M. Plant photoreceptors and their signaling components compete for COP1 binding via VP peptide motifs. EMBO J 2019; 38:e102140. [PMID: 31304983 PMCID: PMC6745501 DOI: 10.15252/embj.2019102140] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [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] [Received: 03/29/2019] [Revised: 05/29/2019] [Accepted: 06/07/2019] [Indexed: 12/31/2022] Open
Abstract
Plants sense different parts of the sun's light spectrum using distinct photoreceptors, which signal through the E3 ubiquitin ligase COP1. Here, we analyze why many COP1‐interacting transcription factors and photoreceptors harbor sequence‐divergent Val‐Pro (VP) motifs that bind COP1 with different binding affinities. Crystal structures of the VP motifs of the UV‐B photoreceptor UVR8 and the transcription factor HY5 in complex with COP1, quantitative binding assays, and reverse genetic experiments together suggest that UVR8 and HY5 compete for COP1. Photoactivation of UVR8 leads to high‐affinity cooperative binding of its VP motif and its photosensing core to COP1, preventing COP1 binding to its substrate HY5. UVR8–VP motif chimeras suggest that UV‐B signaling specificity resides in the UVR8 photoreceptor core. Different COP1–VP peptide motif complexes highlight sequence fingerprints required for COP1 targeting. The blue‐light photoreceptors CRY1 and CRY2 also compete with transcription factors for COP1 binding using similar VP motifs. Thus, our work reveals that different photoreceptors and their signaling components compete for COP1 via a conserved mechanism to control different light signaling cascades.
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Affiliation(s)
- Kelvin Lau
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Roman Podolec
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Richard Chappuis
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland.,Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Michael Hothorn
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland
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Podolec R, Ulm R. Photoreceptor-mediated regulation of the COP1/SPA E3 ubiquitin ligase. Curr Opin Plant Biol 2018; 45:18-25. [PMID: 29775763 DOI: 10.1016/j.pbi.2018.04.018] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/25/2018] [Accepted: 04/29/2018] [Indexed: 05/19/2023]
Abstract
Plants have evolved specific photoreceptors that capture informational cues from sunlight. The phytochrome, cryptochrome, and UVR8 photoreceptors perceive red/far-red, blue/UV-A, and UV-B light, respectively, and control overlapping photomorphogenic responses important for plant growth and development. A major repressor of such photomorphogenic responses is the E3 ubiquitin ligase formed by CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and SUPPRESSOR OF PHYA-105 (SPA) proteins, which acts by regulating the stability of photomorphogenesis-promoting transcription factors. The direct interaction of light-activated photoreceptors with the COP1/SPA complex represses its activity via nuclear exclusion of COP1, disruption of the COP1-SPA interaction, and/or SPA protein degradation. This process enables plants to integrate different light signals at the level of the COP1/SPA complex to enact appropriate photomorphogenic responses according to the light environment.
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Affiliation(s)
- Roman Podolec
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
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Arongaus AB, Chen S, Pireyre M, Glöckner N, Galvão VC, Albert A, Winkler JB, Fankhauser C, Harter K, Ulm R. Arabidopsis RUP2 represses UVR8-mediated flowering in noninductive photoperiods. Genes Dev 2018; 32:1332-1343. [PMID: 30254107 PMCID: PMC6169840 DOI: 10.1101/gad.318592.118] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [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] [Received: 07/05/2018] [Accepted: 08/17/2018] [Indexed: 12/22/2022]
Abstract
Arongaus et al. show that genetic mutation of REPRESSOR OF UV-B PHOTOMORPHOGENESIS 2 (RUP2) renders the facultative long day plant Arabidopsis thaliana a day-neutral plant (specifically under light conditions that include UV-B radiation) and dependent on the UV RESISTANCE LOCUS 8 (UVR8) UV-B photoreceptor. Plants have evolved complex photoreceptor-controlled mechanisms to sense and respond to seasonal changes in day length. This ability allows plants to optimally time the transition from vegetative growth to flowering. UV-B is an important part intrinsic to sunlight; however, whether and how it affects photoperiodic flowering has remained elusive. Here, we report that, in the presence of UV-B, genetic mutation of REPRESSOR OF UV-B PHOTOMORPHOGENESIS 2 (RUP2) renders the facultative long day plant Arabidopsis thaliana a day-neutral plant and that this phenotype is dependent on the UV RESISTANCE LOCUS 8 (UVR8) UV-B photoreceptor. We provide evidence that the floral repression activity of RUP2 involves direct interaction with CONSTANS, repression of this key activator of flowering, and suppression of FLOWERING LOCUS T transcription. RUP2 therefore functions as an essential repressor of UVR8-mediated induction of flowering under noninductive short day conditions and thus provides a crucial mechanism of photoperiodic flowering control.
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Affiliation(s)
- Adriana B Arongaus
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva 4, Switzerland
| | - Song Chen
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva 4, Switzerland
| | - Marie Pireyre
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva 4, Switzerland
| | - Nina Glöckner
- Department of Plant Physiology, Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
| | - Vinicius C Galvão
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Andreas Albert
- Research Unit Environmental Simulation, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - J Barbro Winkler
- Research Unit Environmental Simulation, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Christian Fankhauser
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Klaus Harter
- Department of Plant Physiology, Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva 4, Switzerland.,Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 1211 Geneva 4, Switzerland
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Moriconi V, Binkert M, Costigliolo C, Sellaro R, Ulm R, Casal JJ. Perception of Sunflecks by the UV-B Photoreceptor UV RESISTANCE LOCUS8. Plant Physiol 2018; 177:75-81. [PMID: 29530938 PMCID: PMC5933136 DOI: 10.1104/pp.18.00048] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 02/26/2018] [Indexed: 05/20/2023]
Abstract
Sunflecks, transient patches of light that penetrate through gaps in the canopy and transiently interrupt shade, are eco-physiologically and agriculturally important sources of energy for carbon gain, but our molecular understanding of how plant organs perceive and respond to sunflecks through photoreceptors remains limited. The UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) is a recent addition to the list of plant photosensory receptors, and we have made considerable advances in our understanding of the physiology and molecular mechanisms of action of UVR8 and its signaling pathway. However, the function of UVR8 in the natural environment is poorly understood. Here, we show that the UVR8 dimer/monomer ratio responds quantitatively and reversibly to the intensity of sunflecks that interrupt shade in the field. Sunflecks reduced hypocotyl growth and increased CHALCONE SYNTHASE (CHS) and ELONGATED HYPOCOTYL5 gene expression and CHS protein abundance in wild-type Arabidopsis (Arabidopsis thaliana) seedlings, but the uvr8 mutant was impaired in these responses. UVR8 was also required for normal nuclear dynamics of CONSTITUTIVELY PHOTOMORPHOGENIC1. We propose that UVR8 plays an important role in the plant perception of and response to sunflecks.
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Affiliation(s)
- Victoria Moriconi
- IFEVA, Universidad de Buenos Aires and CONICET, Facultad de Agronomía, 1417 Buenos Aires, Argentina
| | - Melanie Binkert
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva 4, Switzerland
| | - Cecilia Costigliolo
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, 1417 Buenos Aires, Argentina
| | - Romina Sellaro
- IFEVA, Universidad de Buenos Aires and CONICET, Facultad de Agronomía, 1417 Buenos Aires, Argentina
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, 1211 Geneva 4, Switzerland
| | - Jorge J Casal
- IFEVA, Universidad de Buenos Aires and CONICET, Facultad de Agronomía, 1417 Buenos Aires, Argentina
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, 1417 Buenos Aires, Argentina
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Demarsy E, Goldschmidt-Clermont M, Ulm R. Coping with 'Dark Sides of the Sun' through Photoreceptor Signaling. Trends Plant Sci 2018; 23:260-271. [PMID: 29233601 DOI: 10.1016/j.tplants.2017.11.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [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: 09/15/2017] [Revised: 11/16/2017] [Accepted: 11/17/2017] [Indexed: 05/19/2023]
Abstract
Plants grow in constantly changing environments, including highly variable light intensities. Sunlight provides the energy that drives photosynthesis and is thus of the utmost importance for plant growth and the generation of oxygen, which the majority of life on Earth depends on. However, exposure to either insufficient or excess levels of light can have detrimental effects and cause light stress. Whereas exposure to insufficient light limits photosynthetic activity, resulting in 'energy starvation', exposure to excess light can damage the photosynthetic apparatus. Furthermore, strong sunlight is associated with high levels of potentially damaging UV-B radiation. Different classes of photoreceptors play important roles in coping with the negative aspects of sunlight, for which specific mechanisms are emerging that are reviewed here.
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Affiliation(s)
- Emilie Demarsy
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Michel Goldschmidt-Clermont
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
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Bernula P, Crocco CD, Arongaus AB, Ulm R, Nagy F, Viczián A. Expression of the UVR8 photoreceptor in different tissues reveals tissue-autonomous features of UV-B signalling. Plant Cell Environ 2017; 40:1104-1114. [PMID: 28058744 DOI: 10.1111/pce.12904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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: 07/04/2016] [Revised: 12/20/2016] [Accepted: 12/24/2016] [Indexed: 05/04/2023]
Abstract
The Arabidopsis UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8) orchestrates the expression of hundreds of genes, many of which can be associated with UV-B tolerance. UV-B does not efficiently penetrate into tissues, yet UV-B regulates complex growth and developmental responses. To unravel to what extent and how UVR8 located in different tissues contributes to UV-B-induced responses, we expressed UVR8 fused to the YELLOW FLUORESCENT PROTEIN (YFP) under the control of tissue-specific promoters in a uvr8 null mutant background. We show that (1) UVR8 localized in the epidermis plays a major role in regulating cotyledon expansion, and (2) expression of UVR8 in the mesophyll is important to protect adult plants from the damaging effects of UV-B. We found that UV-B induces transcription of selected genes, including the key transcriptional regulator ELONGATED HYPOCOTYL 5 (HY5), only in tissues that express UVR8. Thus, we suggest that tissue-autonomous and simultaneous UVR8 signalling in different tissues mediates, at least partly, developmental and defence responses to UV-B.
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Affiliation(s)
- Péter Bernula
- Institute of Plant Biology, Biological Research Centre, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - Carlos Daniel Crocco
- Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211, Geneva 4, Switzerland
| | - Adriana Beatriz Arongaus
- Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211, Geneva 4, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211, Geneva 4, Switzerland
| | - Ferenc Nagy
- Institute of Plant Biology, Biological Research Centre, Temesvári krt. 62, H-6726, Szeged, Hungary
- Institute of Molecular Plant Science, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JH, UK
| | - András Viczián
- Institute of Plant Biology, Biological Research Centre, Temesvári krt. 62, H-6726, Szeged, Hungary
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Yin R, Ulm R. How plants cope with UV-B: from perception to response. Curr Opin Plant Biol 2017; 37:42-48. [PMID: 28411583 DOI: 10.1016/j.pbi.2017.03.013] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 03/24/2017] [Accepted: 03/28/2017] [Indexed: 05/19/2023]
Abstract
Ultraviolet-B radiation (UV-B) is an intrinsic part of the solar radiation that reaches the Earth's surface and affects the biosphere. Plants have evolved a specific UV-B signaling pathway mediated by the UVR8 photoreceptor that regulates growth, development, and acclimation. Major recent advances have contributed to our understanding of the UVR8 photocycle, UV-B-responsive protein-protein interactions, regulation of UVR8 subcellular localization, and UVR8-regulated physiological responses. Here, we review the latest progress in our understanding of UVR8 signaling and UV-B responses, which includes studies in the unicellular alga Chlamydomonas reinhardtii and the flowering plant Arabidopsis.
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Affiliation(s)
- Ruohe Yin
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
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Tilbrook K, Dubois M, Crocco CD, Yin R, Chappuis R, Allorent G, Schmid-Siegert E, Goldschmidt-Clermont M, Ulm R. UV-B Perception and Acclimation in Chlamydomonas reinhardtii. Plant Cell 2016; 28:966-83. [PMID: 27020958 PMCID: PMC4863380 DOI: 10.1105/tpc.15.00287] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 03/25/2016] [Indexed: 05/03/2023]
Abstract
Plants perceive UV-B, an intrinsic component of sunlight, via a signaling pathway that is mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8) and induces UV-B acclimation. To test whether similar UV-B perception mechanisms exist in the evolutionarily distant green alga Chlamydomonas reinhardtii, we identified Chlamydomonas orthologs of UVR8 and the key signaling factor CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Cr-UVR8 shares sequence and structural similarity to Arabidopsis thaliana UVR8, has conserved tryptophan residues for UV-B photoreception, monomerizes upon UV-B exposure, and interacts with Cr-COP1 in a UV-B-dependent manner. Moreover, Cr-UVR8 can interact with At-COP1 and complement the Arabidopsis uvr8 mutant, demonstrating that it is a functional UV-B photoreceptor. Chlamydomonas shows apparent UV-B acclimation in colony survival and photosynthetic efficiency assays. UV-B exposure, at low levels that induce acclimation, led to broad changes in the Chlamydomonas transcriptome, including in genes related to photosynthesis. Impaired UV-B-induced activation in the Cr-COP1 mutant hit1 indicates that UVR8-COP1 signaling induces transcriptome changes in response to UV-B. Also, hit1 mutants are impaired in UV-B acclimation. Chlamydomonas UV-B acclimation preserved the photosystem II core proteins D1 and D2 under UV-B stress, which mitigated UV-B-induced photoinhibition. These findings highlight the early evolution of UVR8 photoreceptor signaling in the green lineage to induce UV-B acclimation and protection.
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Affiliation(s)
- Kimberley Tilbrook
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Marine Dubois
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Carlos D Crocco
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Ruohe Yin
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Richard Chappuis
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Guillaume Allorent
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Emanuel Schmid-Siegert
- SIB-Swiss Institute of Bioinformatics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Michel Goldschmidt-Clermont
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211 Geneva 4, Switzerland
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Binkert M, Crocco CD, Ekundayo B, Lau K, Raffelberg S, Tilbrook K, Yin R, Chappuis R, Schalch T, Ulm R. Revisiting chromatin binding of the Arabidopsis UV-B photoreceptor UVR8. BMC Plant Biol 2016; 16:42. [PMID: 26864020 PMCID: PMC4750278 DOI: 10.1186/s12870-016-0732-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/06/2016] [Indexed: 05/05/2023]
Abstract
BACKGROUND Plants perceive UV-B through the UV RESISTANCE LOCUS 8 (UVR8) photoreceptor and UVR8 activation leads to changes in gene expression such as those associated with UV-B acclimation and stress tolerance. Albeit functionally unrelated, UVR8 shows some homology with RCC1 (Regulator of Chromatin Condensation 1) proteins from non-plant organisms at the sequence level. These proteins act as guanine nucleotide exchange factors for Ran GTPases and bind chromatin via histones. Subsequent to the revelation of this sequence homology, evidence was presented showing that UVR8 activity involves interaction with chromatin at the loci of some target genes through histone binding. This suggested a UVR8 mode-of-action intimately and directly linked with gene transcription. However, several aspects of UVR8 chromatin association remained undefined, namely the impact of UV-B on the process and how UVR8 chromatin association related to the transcription factor ELONGATED HYPOCOTYL 5 (HY5), which is important for UV-B signalling and has overlapping chromatin targets. Therefore, we have investigated UVR8 chromatin association in further detail. RESULTS Unlike the claims of previous studies, our chromatin immunoprecipitation (ChIP) experiments do not confirm UVR8 chromatin association. In contrast to human RCC1, recombinant UVR8 also does not bind nucleosomes in vitro. Moreover, fusion of a VP16 activation domain to UVR8 did not alter expression of proposed UVR8 target genes in transient gene expression assays. Finally, comparison of the Drosophila DmRCC1 and the Arabidopsis UVR8 crystal structures revealed that critical histone- and DNA-interaction residues apparent in DmRCC1 are not conserved in UVR8. CONCLUSION This has led us to conclude that the cellular activity of UVR8 likely does not involve its specific binding to chromatin at target genes.
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Affiliation(s)
- Melanie Binkert
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Carlos D Crocco
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Babatunde Ekundayo
- Department of Molecular Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Kelvin Lau
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Sarah Raffelberg
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Kimberley Tilbrook
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
- Present Address: CSIRO Agriculture, Canberra, Australia.
| | - Ruohe Yin
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Richard Chappuis
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Thomas Schalch
- Department of Molecular Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva 4, Switzerland.
| | - Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva 4, Switzerland.
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Abstract
Plants are able to sense UV-B through the UV-B photoreceptor UVR8. UV-B photon absorption by a UVR8 homodimer leads to UVR8 monomerization and interaction with the downstream signaling factor COP1. This then initiates changes in gene expression, which lead to several metabolic and morphological alterations. A major response is the activation of mechanisms associated with UV-B acclimation and UV-B tolerance, including biosynthesis of sunscreen metabolites, antioxidants and DNA repair enzymes. To balance the response, UVR8 is inactivated by regulated re-dimerization. Apart from their importance for plants, UVR8 and its interacting protein COP1 have already proved useful for the optogenetic toolkit used to engineer synthetic light-dependent responses.
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Affiliation(s)
- Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211, Geneva, 4, Switzerland.
| | - Gareth I Jenkins
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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Yin R, Arongaus AB, Binkert M, Ulm R. Two distinct domains of the UVR8 photoreceptor interact with COP1 to initiate UV-B signaling in Arabidopsis. Plant Cell 2015; 27:202-13. [PMID: 25627067 PMCID: PMC4330580 DOI: 10.1105/tpc.114.133868] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/23/2014] [Accepted: 01/09/2015] [Indexed: 05/17/2023]
Abstract
UV-B photon reception by the Arabidopsis thaliana homodimeric UV RESISTANCE LOCUS8 (UVR8) photoreceptor leads to its monomerization and a crucial interaction with CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Relay of the subsequent signal regulates UV-B-induced photomorphogenesis and stress acclimation. Here, we report that two separate domains of UVR8 interact with COP1: the β-propeller domain of UVR8 mediates UV-B-dependent interaction with the WD40 repeats-based predicted β-propeller domain of COP1, whereas COP1 activity is regulated by interaction through the UVR8 C-terminal C27 domain. We show not only that the C27 domain is required for UVR8 activity but also that chemically induced expression of the C27 domain is sufficient to mimic UV-B signaling. We further show, in contrast with COP1, that the WD40 repeat proteins REPRESSOR OF UV-B PHOTOMORPHOGENESIS1 (RUP1) and RUP2 interact only with the UVR8 C27 domain. This coincides with their facilitation of UVR8 reversion to the ground state by redimerization and their potential to interact with UVR8 in a UV-B-independent manner. Collectively, our results provide insight into a key mechanism of photoreceptor-mediated signaling and its negative feedback regulation.
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Affiliation(s)
- Ruohe Yin
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Adriana B Arongaus
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Melanie Binkert
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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Binkert M, Kozma-Bognár L, Terecskei K, De Veylder L, Nagy F, Ulm R. UV-B-responsive association of the Arabidopsis bZIP transcription factor ELONGATED HYPOCOTYL5 with target genes, including its own promoter. Plant Cell 2014; 26:4200-13. [PMID: 25351492 PMCID: PMC4247584 DOI: 10.1105/tpc.114.130716] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/18/2014] [Accepted: 10/13/2014] [Indexed: 05/18/2023]
Abstract
In plants subjected to UV-B radiation, responses are activated that minimize damage caused by UV-B. The bZIP transcription factor ELONGATED HYPOCOTYL5 (HY5) acts downstream of the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) and promotes UV-B-induced photomorphogenesis and acclimation. Expression of HY5 is induced by UV-B; however, the transcription factor(s) that regulate HY5 transcription in response to UV-B and the impact of UV-B on the association of HY5 with its target promoters are currently unclear. Here, we show that HY5 binding to the promoters of UV-B-responsive genes is enhanced by UV-B in a UVR8-dependent manner in Arabidopsis thaliana. In agreement, overexpression of REPRESSOR OF UV-B PHOTOMORPHOGENESIS2, a negative regulator of UVR8 function, blocks UV-B-responsive HY5 enrichment at target promoters. Moreover, we have identified a T/G-box in the HY5 promoter that is required for its UV-B responsiveness. We show that HY5 and its homolog HYH bind to the T/G(HY5)-box cis-acting element and that they act redundantly in the induction of HY5 expression upon UV-B exposure. Therefore, HY5 is enriched at target promoters in response to UV-B in a UVR8 photoreceptor-dependent manner, and HY5 and HYH interact directly with a T/G-box cis-acting element of the HY5 promoter, mediating the transcriptional activation of HY5 in response to UV-B.
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Affiliation(s)
- Melanie Binkert
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - László Kozma-Bognár
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Kata Terecskei
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Lieven De Veylder
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Ferenc Nagy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary School of Biological Sciences, University of Edinburgh, EH9 3JR Edinburgh, United Kingdom
| | - Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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Vandenbussche F, Tilbrook K, Fierro AC, Marchal K, Poelman D, Van Der Straeten D, Ulm R. Photoreceptor-mediated bending towards UV-B in Arabidopsis. Mol Plant 2014; 7:1041-1052. [PMID: 24711292 DOI: 10.1093/mp/ssu039] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plants reorient their growth towards light to optimize photosynthetic light capture--a process known as phototropism. Phototropins are the photoreceptors essential for phototropic growth towards blue and ultraviolet-A (UV-A) light. Here we detail a phototropic response towards UV-B in etiolated Arabidopsis seedlings. We report that early differential growth is mediated by phototropins but clear phototropic bending to UV-B is maintained in phot1 phot2 double mutants. We further show that this phototropin-independent phototropic response to UV-B requires the UV-B photoreceptor UVR8. Broad UV-B-mediated repression of auxin-responsive genes suggests that UVR8 regulates directional bending by affecting auxin signaling. Kinetic analysis shows that UVR8-dependent directional bending occurs later than the phototropin response. We conclude that plants may use the full short-wavelength spectrum of sunlight to efficiently reorient photosynthetic tissue with incoming light.
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Affiliation(s)
- Filip Vandenbussche
- Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Kimberley Tilbrook
- Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Ana Carolina Fierro
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, B-3001, Heverlee, Belgium
| | - Kathleen Marchal
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, B-3001, Heverlee, Belgium; Department of Plant Biotechnology and Bioinformatics, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium; Department of Information Technology, IMinds, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Dirk Poelman
- Lumilab, Department of Solid State Sciences, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Roman Ulm
- Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211 Geneva 4, Switzerland
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23
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Tilbrook K, Arongaus AB, Binkert M, Heijde M, Yin R, Ulm R. The UVR8 UV-B Photoreceptor: Perception, Signaling and Response. Arabidopsis Book 2013; 11:e0164. [PMID: 23864838 PMCID: PMC3711356 DOI: 10.1199/tab.0164] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Ultraviolet-B radiation (UV-B) is an intrinsic part of sunlight that is accompanied by significant biological effects. Plants are able to perceive UV-B using the UV-B photoreceptor UVR8 which is linked to a specific molecular signaling pathway and leads to UV-B acclimation. Herein we review the biological process in plants from initial UV-B perception and signal transduction through to the known UV-B responses that promote survival in sunlight. The UVR8 UV-B photoreceptor exists as a homodimer that instantly monomerises upon UV-B absorption via specific intrinsic tryptophans which act as UV-B chromophores. The UVR8 monomer interacts with COP1, an E3 ubiquitin ligase, initiating a molecular signaling pathway that leads to gene expression changes. This signaling output leads to UVR8-dependent responses including UV-B-induced photomorphogenesis and the accumulation of UV-B-absorbing flavonols. Negative feedback regulation of the pathway is provided by the WD40-repeat proteins RUP1 and RUP2, which facilitate UVR8 redimerization, disrupting the UVR8-COP1 interaction. Despite rapid advancements in the field of recent years, further components of UVR8 UV-B signaling are constantly emerging, and the precise interplay of these and the established players UVR8, COP1, RUP1, RUP2 and HY5 needs to be defined. UVR8 UV-B signaling represents our further understanding of how plants are able to sense their light environment and adjust their growth accordingly.
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Affiliation(s)
- Kimberley Tilbrook
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Adriana B. Arongaus
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Melanie Binkert
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Marc Heijde
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Ruohe Yin
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
| | - Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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24
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Müller K, Engesser R, Schulz S, Steinberg T, Tomakidi P, Weber CC, Ulm R, Timmer J, Zurbriggen MD, Weber W. Multi-chromatic control of mammalian gene expression and signaling. Nucleic Acids Res 2013; 41:e124. [PMID: 23625964 PMCID: PMC3695509 DOI: 10.1093/nar/gkt340] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The emergence and future of mammalian synthetic biology depends on technologies for orchestrating and custom tailoring complementary gene expression and signaling processes in a predictable manner. Here, we demonstrate for the first time multi-chromatic expression control in mammalian cells by differentially inducing up to three genes in a single cell culture in response to light of different wavelengths. To this end, we developed an ultraviolet B (UVB)-inducible expression system by designing a UVB-responsive split transcription factor based on the Arabidopsis thaliana UVB receptor UVR8 and the WD40 domain of COP1. The system allowed high (up to 800-fold) UVB-induced gene expression in human, monkey, hamster and mouse cells. Based on a quantitative model, we determined critical system parameters. By combining this UVB-responsive system with blue and red light-inducible gene control technology, we demonstrate multi-chromatic multi-gene control by differentially expressing three genes in a single cell culture in mammalian cells, and we apply this system for the multi-chromatic control of angiogenic signaling processes. This portfolio of optogenetic tools enables the design and implementation of synthetic biological networks showing unmatched spatiotemporal precision for future research and biomedical applications.
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Affiliation(s)
- Konrad Müller
- Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany
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25
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González Besteiro MA, Ulm R. ATR and MKP1 play distinct roles in response to UV-B stress in Arabidopsis. Plant J 2013; 73:1034-1043. [PMID: 23237049 DOI: 10.1111/tpj.12095] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/05/2012] [Accepted: 12/07/2012] [Indexed: 05/27/2023]
Abstract
Ultraviolet-B (UV-B) stress activates MAP kinases (MAPKs) MPK3 and MPK6 in Arabidopsis. MAPK activity must be tightly controlled in order to ensure an appropriate cellular outcome. MAPK phosphatases (MKPs) effectively control MAPKs by dephosphorylation of phosphothreonine and phosphotyrosine in their activation loops. Arabidopsis MKP1 is an important regulator of MPK3 and MPK6, and mkp1 knockout mutants are hypersensitive to UV-B stress, which is associated with reduced inactivation of MPK3 and MPK6. Here, we demonstrate that MPK3 and MPK6 are hyperactivated in response to UV-B in plants that are deficient in photorepair, suggesting that UV-damaged DNA is a trigger of MAPK signaling. This is not due to a block in replication, as, in contrast to atr, the mkp1 mutant is not hypersensitive to the replication-inhibiting drug hydroxyurea, hydroxyurea does not activate MPK3 and MPK6, and atr is not impaired in MPK3 and MPK6 activation in response to UV-B. We further show that mkp1 leaves and roots are UV-B hypersensitive, whereas atr is mainly affected at the root level. Tolerance to UV-B stress has been previously associated with stem cell removal and CYCB1;1 accumulation. Although UV-B-induced stem cell death and CYCB1;1 expression are not altered in mkp1 roots, CYCB1;1 expression is reduced in mkp1 leaves. We conclude that the MKP1 and ATR pathways operate in parallel, with primary roles for ATR in roots and MKP1 in leaves.
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Affiliation(s)
- Marina A González Besteiro
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211, Geneva 4, Switzerland
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26
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Abstract
MAP kinase phosphatases (MKPs) are important regulators of the activation levels and kinetics of MAP kinases. This is crucial for a large number of physiological processes during development and growth, as well as interactions with the environment, including the response to ultraviolet-B (UV-B) stress. Arabidopsis MKP1 is a key regulator of MAP kinases MPK3 and MPK6 in response to UV-B stress. However, virtually nothing is presently known about the post-translational regulation of plant MKPs in vivo. Here, we provide evidence that MKP1 is a phosphoprotein in vivo and that MKP1 accumulates in response to UV-B stress. Moreover, proteasome inhibitor experiments suggest that MKP1 is constantly turned-over under non-stress conditions and that MKP1 is stabilized upon stress treatment. Stress-responsive phosphorylation and stabilization of MKP1 demonstrate the post-translational regulation of a plant MKP in vivo, adding an additional regulatory layer to MAP kinase signaling in plants.
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Affiliation(s)
- Marina A González Besteiro
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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27
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Viczián A, Ádám É, Wolf I, Bindics J, Kircher S, Heijde M, Ulm R, Schäfer E, Nagy F. A short amino-terminal part of Arabidopsis phytochrome A induces constitutive photomorphogenic response. Mol Plant 2012; 5:629-641. [PMID: 22498774 DOI: 10.1093/mp/sss035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phytochrome A (phyA) is the dominant photoreceptor of far-red light sensing in Arabidopsis thaliana. phyA accumulates at high levels in the cytoplasm of etiolated seedlings, and light-induced phyA signaling is mediated by a complex regulatory network. This includes light- and FHY1/FHL protein-dependent translocation of native phyA into the nucleus in vivo. It has also been shown that a short N-terminal fragment of phyA (PHYA406) is sufficient to phenocopy this highly regulated cellular process in vitro. To test the biological activity of this N-terminal fragment of phyA in planta, we produced transgenic phyA-201 plants expressing the PHYA406-YFP (YELLOW FLUORESCENT PROTEIN)-DD, PHYA406-YFP-DD-NLS (nuclear localization signal), and PHYA406-YFP-DD-NES (nuclear export signal) fusion proteins. Here, we report that PHYA406-YFP-DD is imported into the nucleus and this process is partially light-dependent whereas PHYA406-YFP-DD-NLS and PHYA406-YFP-DD-NES display the expected constitutive localization patterns. Our results show that these truncated phyA proteins are light-stable, they trigger a constitutive photomorphogenic-like response when localized in the nuclei, and neither of them induces proper phyA signaling. We demonstrate that in vitro and in vivo PHYA406 Pfr and Pr bind COP1, a general repressor of photomorphogenesis, and co-localize with it in nuclear bodies. Thus, we conclude that, in planta, the truncated PHYA406 proteins inactivate COP1 in the nuclei in a light-independent fashion.
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Affiliation(s)
- András Viczián
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62., H-6726 Szeged, Hungary
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28
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Abstract
Ultraviolet-B radiation (UV-B) is a key environmental signal that is specifically perceived by plants to promote UV acclimation and survival in sunlight. Whereas the plant photoreceptors for visible light are rather well characterised, the UV-B photoreceptor UVR8 was only recently described at the molecular level. Here, we review the current understanding of the UVR8 photoreceptor-mediated pathway in the context of UV-B perception mechanism, early signalling components and physiological responses. We further outline the commonalities in UV-B and visible light signalling as well as highlight differences between these pathways.
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Affiliation(s)
- Marc Heijde
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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29
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González Besteiro MA, Bartels S, Albert A, Ulm R. Arabidopsis MAP kinase phosphatase 1 and its target MAP kinases 3 and 6 antagonistically determine UV-B stress tolerance, independent of the UVR8 photoreceptor pathway. Plant J 2011; 68:727-37. [PMID: 21790814 DOI: 10.1111/j.1365-313x.2011.04725.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Plants perceive UV-B radiation as an informational signal by a pathway involving UVR8 as UV-B photoreceptor, activating photomorphogenic and acclimation responses. In contrast, the response to UV-B as an environmental stress involves mitogen-activated protein kinase (MAPK) signalling cascades. Whereas the perception pathway is plant specific, the UV-B stress pathway is more broadly conserved. Knowledge of the UV-B stress-activated MAPK signalling pathway in plants is limited, and its potential interplay with the UVR8-mediated pathway has not been defined. Here, we show that loss of MAP kinase phosphatase 1 in the mutant mkp1 results in hypersensitivity to acute UV-B stress, but without impairing UV-B acclimation. The MKP1-interacting proteins MPK3 and MPK6 are activated by UV-B stress and are hyperactivated in mkp1. Moreover, mutants mpk3 and mpk6 exhibit elevated UV-B tolerance and partially suppress the UV-B hypersensitivity of mkp1. We show further that the MKP1-regulated stress-response MAPK pathway is independent of the UVR8 photoreceptor, but that MKP1 also contributes to survival under simulated sunlight. We conclude that, whereas UVR8-mediated acclimation in plants promotes UV-B-induced defence measures, MKP1-regulated stress signalling results when UV-B protection and repair are insufficient and damage occurs. The combined activity of these two mechanisms is crucial to UV-B tolerance in plants.
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Affiliation(s)
- Marina A González Besteiro
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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30
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Anderson JC, Bartels S, González Besteiro MA, Shahollari B, Ulm R, Peck SC. Arabidopsis MAP Kinase Phosphatase 1 (AtMKP1) negatively regulates MPK6-mediated PAMP responses and resistance against bacteria. Plant J 2011; 67:258-68. [PMID: 21447069 DOI: 10.1111/j.1365-313x.2011.04588.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A primary component of plant defense is the detection of pathogen-associated molecular patterns (PAMPs) by plasma membrane-localized pathogen recognition receptors. PAMP perception results in rapid and transient activation of phosphorylation-dependent signaling pathways that lead to a wide array of defense-related responses, including extensive changes in gene expression. In Arabidopsis, several kinases, including the mitogen-activated protein kinases (MAPKs) MPK6 and MPK3, are rapidly activated after PAMP treatment, and are thought to positively regulate a wide array of defense-related responses. In contrast, negative regulation of PAMP responses by downstream phosphatases remains poorly understood. Here we report the identification of Arabidopsis MAP Kinase Phosphatase 1 (MKP1) as a negative regulator of diverse PAMP responses, including activation of MPK6 and MPK3, transient production of extracellular reactive oxygen species, accumulation of a subset of PAMP-regulated transcripts, and inhibition of seedling growth. In agreement with the enhanced PAMP response phenotypes observed in the mkp1 mutant, we found that mkp1 seedlings and adult plants are more resistant to the virulent bacterial pathogen Pseudomonas syringae pv. tomato (Pto) DC3000. Further genetic analysis revealed that MPK6, but not MPK3, is required for the mkp1-dependent increase in resistance to Pto and enhanced PAMP-induced growth inhibition observed in mkp1 seedlings. Together, our data support a role for MKP1 as a negative regulator of MPK6-mediated PAMP responses.
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Affiliation(s)
- Jeffrey C Anderson
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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31
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Fehér B, Kozma-Bognár L, Kevei E, Hajdu A, Binkert M, Davis SJ, Schäfer E, Ulm R, Nagy F. Functional interaction of the circadian clock and UV RESISTANCE LOCUS 8-controlled UV-B signaling pathways in Arabidopsis thaliana. Plant J 2011; 67:37-48. [PMID: 21395889 DOI: 10.1111/j.1365-313x.2011.04573.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Circadian clocks regulate many molecular and physiological processes in Arabidopsis (Arabidopsis thaliana), allowing the timing of these processes to occur at the most appropriate time of the day in a 24-h period. The accuracy of timing relies on the synchrony of the clock and the environmental day/night cycle. Visible light is the most potent signal for such synchronization, but light-induced responses are also rhythmically attenuated (gated) by the clock. Here, we report a similar mutual interaction of the circadian clock and non-damaging photomorphogenic UV-B light. We show that low-intensity UV-B radiation acts as entraining signal for the clock. UV RESISTANCE LOCUS 8 (UVR8) and CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) are required, but ELONGATED HYPOCOTYL 5 (HY5) and HY5 HOMOLOG (HYH) are dispensable for this process. UV-B responsiveness of clock gene expression suggests that photomorphogenic UV-B entrains the plant clock through transcriptional activation. We also demonstrate that UV-B induction of gene expression under these conditions is gated by the clock in a HY5/HYH-independent manner. The arrhythmic early flowering 3-4 mutant showed non-gated, high-level gene induction by UV-B, yet displayed no increased tolerance to UV-B stress. Thus, the temporal restriction of UV-B responsiveness by the circadian clock can be considered as saving resources during acclimation without losing fitness.
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Affiliation(s)
- Balázs Fehér
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
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32
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Abstract
Cryptochromes are a class of photosensory receptors that control important processes in animals and plants primarily by regulating gene expression. How photon absorption by cryptochromes leads to changes in gene expression has remained largely elusive. Three recent studies, including Lian and colleagues (pp. 1023-1028) and Liu and colleagues (pp. 1029-1034) in this issue of Genes & Development, demonstrate that the interaction of light-activated Arabidopsis cryptochromes with a class of regulatory components of E3 ubiquitin ligase complexes leads to environmentally controlled abundance of transcriptional regulators.
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Affiliation(s)
- Christian Fankhauser
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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33
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Rizzini L, Favory JJ, Cloix C, Faggionato D, O'Hara A, Kaiserli E, Baumeister R, Schäfer E, Nagy F, Jenkins GI, Ulm R. Perception of UV-B by the Arabidopsis UVR8 protein. Science 2011; 332:103-6. [PMID: 21454788 DOI: 10.1126/science.1200660] [Citation(s) in RCA: 677] [Impact Index Per Article: 52.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
To optimize their growth and survival, plants perceive and respond to ultraviolet-B (UV-B) radiation. However, neither the molecular identity of the UV-B photoreceptor nor the photoperception mechanism is known. Here we show that dimers of the UVR8 protein perceive UV-B, probably by a tryptophan-based mechanism. Absorption of UV-B induces instant monomerization of the photoreceptor and interaction with COP1, the central regulator of light signaling. Thereby this signaling cascade controlled by UVR8 mediates UV-B photomorphogenic responses securing plant acclimation and thus promotes survival in sunlight.
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Affiliation(s)
- Luca Rizzini
- Faculty of Biology, Institute of Biology II, University of Freiburg, D-79104 Freiburg, Germany
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34
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Wolf L, Rizzini L, Stracke R, Ulm R, Rensing SA. The molecular and physiological responses of Physcomitrella patens to ultraviolet-B radiation. Plant Physiol 2010; 153:1123-34. [PMID: 20427465 PMCID: PMC2899899 DOI: 10.1104/pp.110.154658] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 04/26/2010] [Indexed: 05/19/2023]
Abstract
Ultraviolet-B (UV-B) radiation present in sunlight is an important trigger of photomorphogenic acclimation and stress responses in sessile land plants. Although numerous moss species grow in unshaded habitats, our understanding of their UV-B responses is very limited. The genome of the model moss Physcomitrella patens, which grows in sun-exposed open areas, encodes signaling and metabolic components that are implicated in the UV-B response in flowering plants. In this study, we describe the response of P. patens to UV-B radiation at the morphological and molecular levels. We find that P. patens is more capable of surviving UV-B stress than Arabidopsis (Arabidopsis thaliana) and describe the differential expression of approximately 400 moss genes in response to UV-B radiation. A comparative analysis of the UV-B response in P. patens and Arabidopsis reveals both distinct and conserved pathways.
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Affiliation(s)
| | | | | | | | - Stefan A. Rensing
- Institute of Biology II (L.W., L.R., R.U., S.A.R.) and Freiburg Initiative for Systems Biology (L.W., S.A.R.), Faculty of Biology, University of Freiburg, D–79104 Freiburg, Germany; Genome Research, Faculty of Biology, Bielefeld University, D–33594 Bielefeld, Germany (R.S.)
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35
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Bartels S, González Besteiro MA, Lang D, Ulm R. Emerging functions for plant MAP kinase phosphatases. Trends Plant Sci 2010; 15:322-9. [PMID: 20452268 DOI: 10.1016/j.tplants.2010.04.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 04/08/2010] [Accepted: 04/13/2010] [Indexed: 05/24/2023]
Abstract
Reversible phosphorylation is a crucial regulatory mechanism that controls the activity of proteins. In mitogen-activated protein kinase (MAPK) signaling cascades, the cellular response depends on the intensity and duration of the MAPK activation, which is determined by balanced phosphorylation-dephosphorylation. MAPK phosphatases (MKPs), a subgroup of the dual-specificity phosphatases, are major negative regulators of MAPKs. The plant MKP family members are highly diverse in their structure and biological functions, and can be classified into five groups by sequence analysis. We review the recent progress made by genetic studies in identifying the physiological role of plant MKPs in a multitude of cellular processes, including cytoskeleton rearrangement, stress responses and phytohormone signaling, and examine the importance of negative regulators in plant MAPK signaling networks.
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Affiliation(s)
- Sebastian Bartels
- Botany, Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany
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36
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Stracke R, Favory JJ, Gruber H, Bartelniewoehner L, Bartels S, Binkert M, Funk M, Weisshaar B, Ulm R. The Arabidopsis bZIP transcription factor HY5 regulates expression of the PFG1/MYB12 gene in response to light and ultraviolet-B radiation. Plant Cell Environ 2010; 33:88-103. [PMID: 19895401 DOI: 10.1111/j.1365-3040.2009.02061.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plants fend off potentially damaging ultraviolet (UV)-B radiation by synthesizing and accumulating UV-B-absorbing flavonols that function as sunscreens. Regulation of this biosynthetic pathway is largely transcriptional and controlled by a network of transcription factors, among which the PRODUCTION OF FLAVONOL GLYCOSIDES (PFG) family of R2R3-MYB transcription factors was recently identified with a pivotal function. Here, we describe the response of Arabidopsis seedlings to narrow-band UV-B radiation at the level of phenylpropanoid pathway genes using whole-genome transcriptional profiling and identify the corresponding flavonol glycosides accumulating under UV-B. We further show that the bZIP transcriptional regulator ELONGATED HYPOCOTYL5 (HY5) is required for the transcriptional activation of the PFG1/MYB12 and PFG3/MYB111 genes under UV-B and visible light. A synthetic protein composed of HY5 with the VP16 activation domain is sufficient to activate PFG1/MYB12 expression in planta. However, even though myb11 myb12 myb111 triple mutants have strongly reduced CHS levels in darkness as well as in constant light, neither light- nor UV-B-inducibility seems impaired. Notwithstanding this, absence of the three PFG family transcription factors results in reduced UV-B tolerance, whereas PFG1/MYB12 overexpression leads to an increased tolerance. Thus, our data suggest that HY5-dependent regulation of PFG gene expression contributes to the establishment of UV-B tolerance.
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Affiliation(s)
- Ralf Stracke
- Department of Biology, Chair of Genome Research, Bielefeld University, Bielefeld, Germany
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37
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Bartels S, Anderson JC, González Besteiro MA, Carreri A, Hirt H, Buchala A, Métraux JP, Peck SC, Ulm R. MAP kinase phosphatase1 and protein tyrosine phosphatase1 are repressors of salicylic acid synthesis and SNC1-mediated responses in Arabidopsis. Plant Cell 2009; 21:2884-97. [PMID: 19789277 PMCID: PMC2768924 DOI: 10.1105/tpc.109.067678] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 08/28/2009] [Accepted: 09/08/2009] [Indexed: 05/17/2023]
Abstract
Mitogen-activated protein (MAP) kinase phosphatases are important negative regulators of the levels and kinetics of MAP kinase activation that modulate cellular responses. The dual-specificity phosphatase MAP KINASE PHOSPHATASE1 (MKP1) was previously shown to regulate MAP KINASE6 (MPK6) activation levels and abiotic stress responses in Arabidopsis thaliana. Here, we report that the mkp1 null mutation in the Columbia (Col) accession results in growth defects and constitutive biotic defense responses, including elevated levels of salicylic acid, camalexin, PR gene expression, and resistance to the bacterial pathogen Pseudomonas syringae. PROTEIN TYROSINE PHOSPHATASE1 (PTP1) also interacts with MPK6, but the ptp1 null mutant shows no aberrant growth phenotype. However, the pronounced constitutive defense response of the mkp1 ptp1 double mutant reveals that MKP1 and PTP1 repress defense responses in a coordinated fashion. Moreover, mutations in MPK3 and MPK6 distinctly suppress mkp1 and mkp1 ptp1 phenotypes, indicating that MKP1 and PTP1 act as repressors of inappropriate MPK3/MPK6-dependent stress signaling. Finally, we provide evidence that the natural modifier of mkp1 in Col is largely the disease resistance gene homolog SUPPRESSOR OF npr1-1, CONSTITUTIVE 1 (SNC1) that is absent in the Wassilewskija accession. Our data thus indicate a major role of MKP1 and PTP1 in repressing salicylic acid biosynthesis in the autoimmune-like response caused by SNC1.
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Affiliation(s)
- Sebastian Bartels
- Faculty of Biology, Institute of Biology II, University of Freiburg, D-79104 Freiburg, Germany
| | - Jeffrey C. Anderson
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211
| | - Marina A. González Besteiro
- Faculty of Biology, Institute of Biology II, University of Freiburg, D-79104 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Alessandro Carreri
- Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
| | - Heribert Hirt
- Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
- Unité de Recherche en Génomique Végétale-Plant Genomics, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, University Evry, F-91057 Evry Cedex, France
| | - Antony Buchala
- Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Jean-Pierre Métraux
- Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Scott C. Peck
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211
| | - Roman Ulm
- Faculty of Biology, Institute of Biology II, University of Freiburg, D-79104 Freiburg, Germany
- Centre for Biological Signaling Studies (bioss), University of Freiburg, D-79104 Freiburg, Germany
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Safrany J, Haasz V, Mate Z, Ciolfi A, Feher B, Oravecz A, Stec A, Dallmann G, Morelli G, Ulm R, Nagy F. Identification of a novel cis-regulatory element for UV-B-induced transcription in Arabidopsis. Plant J 2008; 54:402-14. [PMID: 18266923 DOI: 10.1111/j.1365-313x.2008.03435.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultraviolet-B light (UV-B) regulates the expression of genes in a wavelength- and fluence rate-dependent fashion. A signaling pathway consisting of CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) and UV RESISTANCE LOCUS 8 (UVR 8) mediates responsiveness to longer wavelength, low intensity UV-B light-activating, for example, HY5 gene expression. By contrast, transcription of another group of genes, including ANAC13, modulated by shorter wavelength, higher intensity UV-B is controlled by a yet unknown and largely COP1-independent signaling cascade. Here we provide evidence by promoter deletion analysis, and characterization of genetic mutants displaying aberrant expression patterns, that two cis-regulatory elements, designated MRE(ANAC13) and UVBox(ANAC13), are required for maximal UV-B induction of the ANAC13 gene in transgenic plants. These elements are located in the proximal 150-bp region of the ANAC13 promoter. They show no significant similarity to each other; the putative MRE(ANAC13) (-AACCTT-) is closely related to MRE(CHS) (-AACCTA-) found in the CHALCONE SYNTHASE (CHS) gene, whereas UVBox(ANAC13) (with core sequence CAAG) represents a novel cis-regulatory element. The novel UVBox(ANAC13) sequence is significantly enriched in the promoter region of a subset of UV-B-induced genes with similar activation properties as ANAC13. In addition, we demonstrate that expression of a chimeric gene containing only the dimerized 12-mer containing UVBox(ANAC13) fused to a minimal CaMV35S promoter/luciferase reporter is (i) efficiently induced by shorter wavelength, higher intensity UV-B, but (ii) does not respond either to longer wavelength UV-B and red light or (iii) to abscisic acid treatment and osmotic, salt, heat and cold stresses.
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Affiliation(s)
- Judit Safrany
- Agricultural Biotechnology Center, Szent-Gyorgyi A. 4, H-2100 Gödöllo, Hungary
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Oravecz A, Baumann A, Máté Z, Brzezinska A, Molinier J, Oakeley EJ, Adám E, Schäfer E, Nagy F, Ulm R. CONSTITUTIVELY PHOTOMORPHOGENIC1 is required for the UV-B response in Arabidopsis. Plant Cell 2006; 18:1975-90. [PMID: 16829591 PMCID: PMC1533968 DOI: 10.1105/tpc.105.040097] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 05/11/2006] [Accepted: 06/19/2006] [Indexed: 05/10/2023]
Abstract
CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) is a negative regulator of photomorphogenesis in Arabidopsis thaliana. COP1 functions as an E3 ubiquitin ligase, targeting select proteins for proteasomal degradation in plants as well as in mammals. Among its substrates is the basic domain/leucine zipper (bZIP) transcription factor ELONGATED HYPOCOTYL5 (HY5), one of the key regulators of photomorphogenesis under all light qualities, including UV-B responses required for tolerance to this environmental threat. Here, we report that, in contrast with the situation in visible light, COP1 is a critical positive regulator of responses to low levels of UV-B. We show that in the cop1-4 mutant, flavonoid accumulation and genome-wide expression changes in response to UV-B are blocked to a large extent. COP1 is required for HY5 gene activation, and both COP1 and HY5 proteins accumulate in the nucleus under supplementary UV-B. SUPPRESSOR OF PHYTOCHROME A-105 family proteins (SPA1 to SPA4) that are required for COP1 function in dark and visible light are not essential in the response to UV-B. We conclude that COP1 performs a specific and novel role in the plants' photomorphogenic response to UV-B, coordinating HY5-dependent and -independent pathways, which eventually results in UV-B tolerance.
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Affiliation(s)
- Attila Oravecz
- Institute of Biology II/Botany, University of Freiburg, D-79104 Freiburg, Germany
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Abstract
In contrast to phytochrome-, cryptochrome- and phototropin-sensing systems, about which considerable knowledge has accumulated, the ultraviolet-B (UVB) photoreceptor is not yet known at the molecular level. Information about the downstream signalling events that underlie UVB-provoked physiological responses is limited. Recent whole-genome transcript profiling, isolation of mutants that are impaired in specific UVB-induced responses and detailed photobiological studies suggest that responses that are triggered by shorter wavelength UVB and longer wavelength UVB are mediated by two different sensory systems. The bZIP transcription factor HY5 was recently identified as an important player in the long-wavelength UVB-induced signal transduction cascade. Advances in the development of luciferase-reporter lines will make it feasible to perform high-throughput genetic screens to isolate novel mutants that are impaired in sensing or transducing signals downstream of the putative UVB photoreceptor(s).
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Affiliation(s)
- Roman Ulm
- Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
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Ulm R, Baumann A, Oravecz A, Máté Z, Adám E, Oakeley EJ, Schäfer E, Nagy F. Genome-wide analysis of gene expression reveals function of the bZIP transcription factor HY5 in the UV-B response of Arabidopsis. Proc Natl Acad Sci U S A 2004; 101:1397-402. [PMID: 14739338 PMCID: PMC337064 DOI: 10.1073/pnas.0308044100] [Citation(s) in RCA: 355] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Indexed: 11/18/2022] Open
Abstract
The light environment is a key factor that governs a multitude of developmental processes during the entire life cycle of plants. An important and increasing part of the incident sunlight encompasses a segment of the UV-B region (280-320 nm) that is not entirely absorbed by the ozone layer in the stratosphere of the earth. This portion of the solar radiation, which inevitably reaches the sessile plants, can act both as an environmental stress factor and an informational signal. To identify Arabidopsis genes involved in the UV response, we monitored the gene expression profile of UV-B-irradiated seedlings by using high-density oligonucleotide microarrays comprising almost the full Arabidopsis genome (>24,000 genes). A robust set of early low-level UV-B-responsive genes, 100 activated and 7 repressed, was identified. In all cases analyzed, UV-B induction was found to be independent of known photoreceptors. This group of genes is suggested to represent the molecular readout of the signaling cascade triggered by the elusive UV-B photoreceptor(s). Moreover, our analysis identified interactions between cellular responses to different UV-B ranges that led us to postulate the presence of partially distinct but interacting UV-B perception and signaling mechanisms. Finally, we demonstrate that the bZIP transcription factor HY5 is required for UV-B-mediated regulation of a subset of genes.
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Affiliation(s)
- Roman Ulm
- Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
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Ulm R, Ichimura K, Mizoguchi T, Peck SC, Zhu T, Wang X, Shinozaki K, Paszkowski J. Distinct regulation of salinity and genotoxic stress responses by Arabidopsis MAP kinase phosphatase 1. EMBO J 2002; 21:6483-93. [PMID: 12456655 PMCID: PMC136950 DOI: 10.1093/emboj/cdf646] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The Arabidopsis genome contains 20 genes encoding mitogen-activated protein kinases (MAPKs), which drastically outnumbers genes for their negative regulators, MAP kinase phosphatases (MKPs) (five at most). This contrasts sharply with genomes of other eukaryotes where the number of MAPKs and MKPs is approximately equal. MKPs may therefore play an important role in signal integration in plants, through concerted regulation of several MAPKs. Our previous studies identified Arabidopsis MKP1 and showed that its deficiency in the mkp1 mutant results in plant hypersensitivity to genotoxic stress. Here, we identify a set of MAPKs that interact with MKP1, and show that the activity level of one of these, MPK6, is regulated by MKP1 in vivo. Moreover, using expression profiling, we identified a specific group of genes that probably represent targets of MKP1 regulation. Surprisingly, the identity of these genes and interacting MAPKs suggested involvement of MKP1 in salt stress responses. Indeed, mkp1 plants have increased resistance to salinity. Thus MKP1 apparently plays a pivotal role in the integration and fine-tuning of plant responses to various environmental challenges.
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Affiliation(s)
- Roman Ulm
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Kazuya Ichimura
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Tsuyoshi Mizoguchi
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Scott C. Peck
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Tong Zhu
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Xun Wang
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Kazuo Shinozaki
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
| | - Jerzy Paszkowski
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland, Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan and Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA Present address: Institute of Biology II/Botany, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany Present address: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK Corresponding author e-mail:
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Ulm R, Mittelsten Scheid O. A hairy tale: Glabrous meets Werewolf. Trends Plant Sci 2001; 6:343. [PMID: 11495767 DOI: 10.1016/s1360-1385(01)02059-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Ulm R, Revenkova E, di Sansebastiano GP, Bechtold N, Paszkowski J. Mitogen-activated protein kinase phosphatase is required for genotoxic stress relief in Arabidopsis. Genes Dev 2001; 15:699-709. [PMID: 11274055 PMCID: PMC312655 DOI: 10.1101/gad.192601] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Genotoxic stress activates complex cellular responses allowing for the repair of DNA damage and proper cell recovery. Although plants are exposed constantly to increasing solar UV irradiation, the signaling cascades activated by genotoxic environments are largely unknown. We have identified an Arabidopsis mutant (mkp1) hypersensitive to genotoxic stress treatments (UV-C and methyl methanesulphonate) due to disruption of a gene that encodes an Arabidopsis homolog of mitogen-activated protein kinase phosphatase (AtMKP1). Growth of the mkp1 mutant under standard conditions is indistinguishable from wild type, indicating a stress-specific function of AtMKP1. MAP kinase phosphatases (MKPs), the potent inactivators of MAP kinases, are considered important regulators of MAP kinase signaling. Although biochemical data from mammalian cell cultures suggests an involvement of MKPs in cellular stress responses, there is no in vivo genetic support for this view in any multicellular organism. The genetic and biochemical data presented here imply a central role for a MAP kinase cascade in genotoxic stress signaling in plants and indicate AtMKP1 to be a crucial regulator of the MAP kinase activity in vivo, determining the outcome of the cellular reaction and the level of genotoxic resistance.
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Affiliation(s)
- R Ulm
- Friedrich Miescher Institute, CH-4002 Basel, Switzerland.
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Ulm R, Mittelsten Scheid O. A conduit for T-DNA through the plant cell membrane: dig it yourself! Trends Plant Sci 2000; 5:514. [PMID: 11120462 DOI: 10.1016/s1360-1385(00)01807-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Huber H, Knogler W, Kucera H, Ulm R. [Cytologic endometrial changes following high-dose iridium-192 radiation]. Strahlentherapie 1983; 159:286-9. [PMID: 6857743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
By intrauterine exfoliative smear performed twice in each of seventeen patients, the cytomorphologic effect of an iridium-192 after-loading irradiation was demonstrated. The examinations showed that the cytologic findings were characteristic of the effect of ionizing radiation even in case of the histologically unchanged, not radiosensitive cylindrical epithelium. After the iridium irradiation of malignantly transformed cells of the cylindrical epithelium with 1000 rd, vacuolation and pseudoeosinophilia were the predominant lesions, while after 2000 rd this was above all the presence of macronucleoli. A marked cellular diathesis is a characteristic result of the irradiation with iridium-192. Although hyperchromasia is not an absolute sign of malignancy in case of the adenocarcinoma, it should be mentioned that chromatin concentrations are scarcely found after irradiation.
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Spona J, Ulm R, Bieglmayer C, Husslein P. Hormone serum levels and hormone receptor contents of endometria in women with normal menstrual cycles and patients bearing endometrial carcinoma. Gynecol Obstet Invest 1979; 10:71-80. [PMID: 535775 DOI: 10.1159/000299920] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (HPRL), 17 beta-estradiol (E2) and progesterone (P) were estimated in 46 subjects with normal menstrual cycles in whom hysterectomies were performed. Estrogen (ER) and progesterone receptor (PgR) levels in endometrial samples of these patients were estimated, and histological dating of the cycle day was carried out. Similarly, hormone serum levels and ER as well as PgR were estimated in 17 patients with endometrial carcinoma. No correlation between LH, FSH, HPRL and ER as well as PgR was noted in the normal subjects. Correlation between P and ER was observed in this group. Parallel variations between E2 and PgR were recorded in the normal females. In the carcinoma group no correlations between hormone serum levels and receptor contents were found, but ER and PgR correlated with each other. Receptor levels was highest in the well-differentiated group of endometrial carcinoma. The present experiments provide a rationale for progestagen therapy of carcinoma of the endometrium.
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Michalica W, Schneider W, Sona J, Ulm R. [Endogenous oestrogen state in women with postmenopausal bleeding (author's transl)]. Wien Klin Wochenschr 1976; 88:742-5. [PMID: 997552] [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: 12/25/2022]
Abstract
The endogenous oestrogen state in 52 women (33 with endometrial carcinoma and 19 with benign conditions of the endometrium) was assessed ny means of histological examinations of vaginal swabs and of radio-immunological determinations of 17 beta-oestradiol. Considering their age, these women displayed an oestrogen activity far exceeding that found in previous studies. There was no difference between the oestrogen levels in women with carcinoma and the other patients. Furthermore, it was stiking that in the same group of women the examined parameters frequently showed different results. Consequently, a diagnosis based solely on the investigation of one parameter must frequently be misleading.
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Wolf G, Kucera H, Ulm R, Kubista E, Müller-Tyl E, Szekely E. [Experiences with mammography, plate thermography and cytology as triple diagnosis]. Strahlentherapie 1976; 152:248-53. [PMID: 968924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A report is given on 814 patients who had undergone a mamma examination by means of mammographies, plate thermographies, and, if indicated, punction cytologies. On the basis of our experiences with this triple diagnosis we drafted a preliminary control scheme.
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