title: MicroRNA408 is critical for the HY5-SPL7 gene network that mediates the coordinated response to light and copper.
abstract: Light and copper are important environmental determinants of plant growth and development. Despite the wealth of knowledge on both light and copper signaling, the molecular mechanisms that integrate the two pathways remain poorly understood. Here, we use Arabidopsis thaliana to demonstrate an interaction between SQUAMOSA PROMOTER BINDING PROTEIN-LIKE7 (SPL7) and ELONGATED HYPOCOTYL5 (HY5), which mediate copper and light signaling, respectively. Through whole-genome chromatin immunoprecipitation and RNA sequencing analyses, we elucidated the SPL7 regulon and compared it with that of HY5. We found that the two transcription factors coregulate many genes, including those involved in anthocyanin accumulation and photosynthesis. Moreover, SPL7 and HY5 act coordinately to transcriptionally regulate MIR408, which results in differential expression of microRNA408 (miR408) and its target genes in response to changing light and copper conditions. We demonstrate that this regulation is tied to copper allocation to the chloroplast and plastocyanin levels. Finally, we found that constitutively activated miR408 rescues the distinct developmental defects of the hy5, spl7, and hy5 spl7 mutants. These findings revealed the existence of crosstalk between light and copper, mediated by a HY5-SPL7 network. Furthermore, integration of transcriptional and posttranscriptional regulation is critical for governing proper metabolism and development in response to combined copper and light signaling.
authors.affiliation: State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China Department of Biology, University of Virginia, Charlottesville, Virginia 22904 College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, China.
authors.forename: Huiyong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, Virginia 22904.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520 State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Jigang
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205.
authors.forename: Huaqing
authors.initials: H
authors.lastname: Cai
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520.
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China Department of Biology, University of Virginia, Charlottesville, Virginia 22904 lei.li@pku.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D047369:Chromatin Immunoprecipitation; D003300:Copper / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D018745:Genome, Plant; D008027:Light; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017423:Sequence Analysis, RNA; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C109254:HY5 protein, Arabidopsis; C000602078:MIRN408 microRNA, Arabidopsis; D035683:MicroRNAs; D009687:Nuclear Proteins; C483288:SPL7 protein, Arabidopsis; D014157:Transcription Factors; D003300:Copper