Revisiting chromatin binding of the Arabidopsis UV-B photoreceptor UVR8

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-Binduced 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 UVR8W285A 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-Binduced UVR8 nuclear accumulation and in UVR8-mediated UV-B signaling.nuclear accumulation | UV-B photoreceptor | COP1 | glucocorticoid receptor | UVR8

show abstract

“…However, it should be noted that chromatin association of UVR8 has recently been challenged (39). Independent of this controversy, the GFP-UVR8…”

Section: Chemically Regulated Nuclear Import Of Gr-cop1 Coimports Uvr8mentioning

confidence: 99%

COP1 is required for UV-B–induced nuclear accumulation of the UVR8 photoreceptor

Yin

Skvortsova

Loubéry

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

127

114

View full text Add to dashboard Cite

show abstract

“…The significance of the association of UVR8 with chromatin remains an enigma; it is not clear whether the detection by ChIP of UVR8 at some loci it regulates (Brown et al 2005; Cloix and Jenkins 2008) indicates a functional necessity for the recruitment and/or activation of chromatin modifiers and/or transcription factors, which would underpin transcriptional regulation, or whether the association is simply due to non-specific chromatin binding because of an affinity for histones (Brown et al 2005; Cloix and Jenkins 2008). UVR8’s association with chromatin is certainly much weaker than that of transcription factors such as HY5, raising questions regarding its significance (Binkert et al 2016). The main objectives of this study were to test whether UVR8 influenced transcription through chromatin modification and to investigate whether it interacted directly with several known chromatin modifiers.…”

Section: Discussionmentioning

confidence: 99%

“…Conversely, it is important to keep in mind that the association of UVR8 with chromatin might be non-specific, resulting from UVR8’s ability to stick to histones during chromatin isolation. Binkert et al (2016) recently questioned the in vivo UVR8-chromatin association after failing to detect UVR8 on certain loci, including HY5 .…”

Section: Introductionmentioning

confidence: 99%

Regulation of transcription by the Arabidopsis UVR8 photoreceptor involves a specific histone modification

2016

View full text Add to dashboard Cite

The photoreceptor UV RESISTANCE LOCUS 8 (UVR8) specifically mediates photomorphogenic responses to UV-B wavelengths. UVR8 acts by regulating transcription of a set of genes, but the underlying mechanisms are unknown. Previous research indicated that UVR8 can associate with chromatin, but the specificity and functional significance of this interaction are not clear. Here we show, by chromatin immunoprecipitation, that UV-B exposure of Arabidopsis increases acetylation of lysines K9 and/or K14 of histone H3 at UVR8-regulated gene loci in a UVR8-dependent manner. The transcription factors HY5 and/or HYH, which mediate UVR8-regulated transcription, are also required for this chromatin modification, at least for the ELIP1 gene. Furthermore, sequencing of the immunoprecipitated DNA revealed that all UV-B-induced enrichments in H3K9,14diacetylation across the genome are UVR8-dependent, and approximately 40 % of the enriched loci contain known UVR8-regulated genes. In addition, inhibition of histone acetylation by anacardic acid reduces the UV-B induced, UVR8 mediated expression of ELIP1 and CHS. No evidence was obtained in yeast 2-hybrid assays for a direct interaction between either UVR8 or HY5 and several proteins involved in light-regulated histone modification, nor for the involvement of these proteins in UVR8-mediated responses in plants, although functional redundancy between proteins could influence the results. In summary, this study shows that UVR8 regulates a specific chromatin modification associated with transcriptional regulation of a set of UVR8-target genes.Electronic supplementary materialThe online version of this article (doi:10.1007/s11103-016-0522-3) contains supplementary material, which is available to authorized users.

show abstract

“…Although HY5 plays critical roles in UVB signaling, it lacks a transcriptional activation domain and cannot alone activate transcription Stracke et al, 2010). In addition, UVR8 does not seem to interact directly with HY5 (Heijde et al, 2013;Binkert et al, 2016). Binkert et al (2016) suggested that there may be HY5 partner protein(s) that provide a transcriptional activation domain and enable UVB responsive gene expression.…”

Section: Role Of Sh1 In Lduvb-dependent Hypocotyl Elongation: a Modelmentioning

confidence: 99%

“…In addition, UVR8 does not seem to interact directly with HY5 (Heijde et al, 2013;Binkert et al, 2016). Binkert et al (2016) suggested that there may be HY5 partner protein(s) that provide a transcriptional activation domain and enable UVB responsive gene expression. In this study, significant differences in expression for CsHY5, but not for CsCOP1 and CsUVR8, were observed between UVB-sensitive and insensitive NILs.…”

Section: Role Of Sh1 In Lduvb-dependent Hypocotyl Elongation: a Modelmentioning

confidence: 99%

SHORT HYPOCOTYL 1 Encodes a SMARCA3-like Chromatin Remodeling Factor Regulating Elongation

Bo¹,

Wang²,

Pan³

et al. 2016

Plant Physiol.

View full text Add to dashboard Cite

(Y.We.).In Arabidopsis (Arabidopsis thaliana), the UVR8-mediated signaling pathway is employed to attain UVB protection and acclimation to deal with low-dosage UVB (LDUVB)-induced stresses. Here, we identified SHORT HYPOCOTYL1 (SH1) in cucumber (Cucumis sativus), which regulates LDUVB-dependent hypocotyl elongation by modulating the UVR8 signaling pathway. We showed that hypocotyl elongation in cucumbers carrying the recessive sh1 allele was LDUVB insensitive and that Sh1 encoded a human SMARCA3-like chromatin remodeling factor. The allele frequency and distribution pattern at this locus among natural populations supported the wild cucumber origin of sh1 for local adaptation, which was under selection during domestication. The cultivated cucumber carries predominantly the Sh1 allele; the sh1 allele is nearly fixed in the semiwild Xishuangbanna cucumber, and the wild cucumber population is largely at Hardy-Weinberg equilibrium for the two alleles. The SH1 protein sequence was highly conserved among eukaryotic organisms, but its regulation of hypocotyl elongation in cucumber seems to be a novel function. While Sh1 expression was inhibited by LDUVB, its transcript abundance was highly correlated with hypocotyl elongation rate and the expression level of cell-elongationrelated genes. Expression profiling of key regulators in the UVR8 signaling pathway revealed significant differential expression of CsHY5 between two near isogenic lines of Sh1. Sh1 and CsHY5 acted antagonistically at transcriptional level. A working model was proposed in which Sh1 regulates LDUVB-dependent hypocotyl elongation in cucumber through changing the chromatin states and thus the accessibility of CsHY5 in the UVR8 signaling pathway to promoters of LDUVB-responsive genes for hypocotyl elongation.The hypocotyl of dicotyledonous plants is the embryonic stem connecting the two embryonic leaves (cotyledons) and the primary root (radicle). The hypocotyl, which has a relatively simple architecture (Scheres et al., 1994), is a very plastic organ, strongly influenced by both external and internal cues known to regulate cell elongation, such as light, gravity, temperature, and hormones. In Arabidopsis (Arabidopsis thaliana), after germination, hypocotyl growth relies mainly on longitudinal cell elongation rather than cell divisions; its length can increase by more than 10-fold (Gendreau et al., 1997). The morphological simplicity, growth behavior, availability of mutants, and ease of phenotyping of mutants of this organ makes it a model for understanding the mechanism of cell elongation and various biological events that participate in its control (Gendreau et al., 1997;Vandenbussche et al., 2005;Boron and Vissenberg, 2014).In nature, the development of germinated seeds starts under soil cover; the seedling undergoing skotomorphogenic growth has a very long hypocotyl, which allows quick attaining of light and de-etiolation after

show abstract

Revisiting chromatin binding of the Arabidopsis UV-B photoreceptor UVR8

Cited by 32 publications

References 53 publications

COP1 is required for UV-B–induced nuclear accumulation of the UVR8 photoreceptor

COP1 is required for UV-B–induced nuclear accumulation of the UVR8 photoreceptor

Regulation of transcription by the Arabidopsis UVR8 photoreceptor involves a specific histone modification

SHORT HYPOCOTYL 1 Encodes a SMARCA3-like Chromatin Remodeling Factor Regulating Elongation

Contact Info

Product

Resources

About