title: COP1 is required for UV-B-induced nuclear accumulation of the UVR8 photoreceptor.
abstract: The UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8) promotes UV-B acclimation and tolerance in Arabidopsis thaliana UVR8 localizes to both cytosol and nucleus, but its main activity is assumed to be nuclear. UV-B photoreception stimulates nuclear accumulation of UVR8 in a presently unknown manner. Here, we show that CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) is required for UV-B-induced nuclear accumulation of UVR8, but bypassing the COP1 requirement for UVR8 nuclear accumulation did not rescue the cop1 mutant UV-B phenotype. Using a glucocorticoid receptor (GR)-based fusion protein system to conditionally localize GR-UVR8 to the nucleus, we have demonstrated that both photoactivation and nuclear localization of UVR8 are required for UV-B-induced photomorphogenic responses. In contrast, there was no UV-B response when UV-B-activated UVR8 was artificially retained in the cytosol. In agreement with a predominantly nuclear activity, constitutively active UVR8(W285A) accumulated in the nucleus also in the absence of UV-B. Furthermore, GR-COP1 expression lines suggested that UV-B-activated UVR8 can be coimported into the nucleus by COP1. Our data strongly support localization of UVR8 signaling in the nucleus and a dual role for COP1 in the regulation of UV-B-induced UVR8 nuclear accumulation and in UVR8-mediated UV-B signaling.
authors.affiliation: Department of Botany and Plant Biology, University of Geneva, CH-1211 Geneva 4, Switzerland;
authors.forename: Ruohe
authors.identifier: 0000-0001-6782-4651
authors.initials: R
authors.lastname: Yin
authors.affiliation: Department of Botany and Plant Biology, University of Geneva, CH-1211 Geneva 4, Switzerland;
authors.forename: Mariya Y
authors.initials: MY
authors.lastname: Skvortsova
authors.affiliation: Department of Botany and Plant Biology, University of Geneva, CH-1211 Geneva 4, Switzerland;
authors.forename: Sylvain
authors.initials: S
authors.lastname: Loubéry
authors.affiliation: Department of Botany and Plant Biology, University of Geneva, CH-1211 Geneva 4, Switzerland; Institute of Genetics and Genomics of Geneva, University of Geneva, CH-1211 Geneva 4, Switzerland roman.ulm@unige.ch.
authors.forename: Roman
authors.identifier: 0000-0001-8014-7392
authors.initials: R
authors.lastname: Ulm
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000528:radiation effects; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism* / Q000528:radiation effects; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D009154:Mutation; D055519:Photoreceptors, Plant / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000235:genetics; D044767:Ubiquitin-Protein Ligases; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D055519:Photoreceptors, Plant; C525052:Uvr8 protein, Arabidopsis; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases
keywords: COP1; UV-B photoreceptor; UVR8; glucocorticoid receptor; nuclear accumulation