Zhang Huiyong, Zhao Xin, Li Jigang, Cai Huaqing, Deng Xing Wang, Li Lei
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.
Department of Biology, University of Virginia, Charlottesville, Virginia 22904.
Plant Cell. 2014 Dec;26(12):4933-53. doi: 10.1105/tpc.114.127340. Epub 2014 Dec 16.
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.
光和铜是植物生长发育的重要环境决定因素。尽管对光信号和铜信号已有丰富的认识，但整合这两条信号通路的分子机制仍知之甚少。在此，我们利用拟南芥证明了分别介导铜信号和光信号的SQUAMOSA启动子结合蛋白样7（SPL7）和下胚轴伸长5（HY5）之间存在相互作用。通过全基因组染色质免疫沉淀和RNA测序分析，我们阐明了SPL7调控子，并将其与HY5的调控子进行了比较。我们发现这两个转录因子共同调控许多基因，包括参与花青素积累和光合作用的基因。此外，SPL7和HY5协同作用，转录调控MIR408，从而导致微小RNA408（miR408）及其靶基因在光照和铜条件变化时发生差异表达。我们证明这种调控与铜向叶绿体的分配和质体蓝素水平有关。最后，我们发现组成型激活的miR408能挽救hy5、spl7和hy5 spl7突变体的明显发育缺陷。这些发现揭示了由HY5-SPL7网络介导的光信号和铜信号之间存在串扰。此外，转录调控和转录后调控的整合对于响应铜信号和光信号的组合来控制适当的代谢和发育至关重要。
