title: Arabidopsis FHY3 and HY5 positively mediate induction of COP1 transcription in response to photomorphogenic UV-B light.
abstract: As sessile organisms, higher plants have evolved the capacity to sense and interpret diverse light signals to modulate their development. In Arabidopsis thaliana, low-intensity and long-wavelength UV-B light is perceived as an informational signal to mediate UV-B-induced photomorphogenesis. Here, we report that the multifunctional E3 ubiquitin ligase, CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1), a known key player in UV-B photomorphogenic responses, is also a UV-B-inducible gene. Two transcription factors, FAR-RED ELONGATED HYPOCOTYL3 (FHY3) and ELONGATED HYPOCOTYL5 (HY5), directly bind to distinct regulatory elements within the COP1 promoter, which are essential for the induction of the COP1 gene mediated by photomorphogenic UV-B signaling. Absence of FHY3 results in impaired UV-B-induced hypocotyl growth and reduced tolerance against damaging UV-B. Thus, FHY3 positively regulates UV-B-induced photomorphogenesis by directly activating COP1 transcription, while HY5 promotes COP1 expression via a positive feedback loop. Furthermore, FHY3 and HY5 physically interact with each other, and this interaction is diminished by UV-B. Together, our findings reveal that COP1 gene expression in response to photomorphogenic UV-B is controlled by a combinatorial regulation of FHY3 and HY5, and this UV-B-specific working mode of FHY3 and HY5 is distinct from that in far-red light and circadian conditions.
authors.affiliation: College of Life Sciences, Beijing Normal University, Beijing 100875, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
authors.forename: Xinhao
authors.initials: X
authors.lastname: Ouyang
authors.forename: Panyu
authors.initials: P
authors.lastname: Yang
authors.forename: On Sun
authors.initials: OS
authors.lastname: Lau
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Jigang
authors.initials: J
authors.lastname: Li
authors.forename: Haodong
authors.initials: H
authors.lastname: Chen
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D059372:Nucleotide Motifs; D010641:Phenotype; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D036226:Seedlings / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D017384:Sequence Deletion; D015398:Signal Transduction; D013997:Time Factors; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C452847:FHY3 protein, Arabidopsis; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D010834:Phytochrome; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases