PDF(Pubmed)
Abstract：
A subset of eukaryotic transcription factors (TFs) possess the ability to reprogram one cell type into another. Genes important for cellular reprograming are typically located in closed chromatin, which is covered by nucleosomes. Pioneer factors are a special class of TFs that can initially engage their target sites in closed chromatin prior to the engagement with, opening of, or modification of the sites by other factors. Although many pioneer factors are known in animals, a few have been characterized in plants. The TF LEAFY (LFY) acts as a pioneer factor specifying floral fate in Arabidopsis. In response to endogenous and environmental cues, plants produce appropriate floral inducers (florigens). During the vegetative phase, LFY is repressed by the TERMINAL FLOWER 1 (TFL1)-FD complex, which functions as a floral inhibitor, or anti-florigen. The florigen FLOWERING LOCUS T (FT) competes with TFL1 to prevent the binding of the FD TF to the LFY locus. The resulting FT-FD complex functions as a transient stimulus to activate its targets. Once LFY has been transcribed in the appropriate spatiotemporal manner, LFY binds to nucleosomes in closed chromatin regions. Subsequently, LFY opens the chromatin by displacing H1 linker histones and recruiting the SWI/SNF chromatin-remodeling complex. Such local changes permit the binding of other TFs, leading to the expression of the floral meristem identity gene APETALA1. This mini-review describes the latest advances in our understanding of the pioneer TF LFY, providing insight into the establishment of gene expression competence through the shaping of the plant epigenetic landscape.
摘要：
真核转录因子（TF）的子集具有将一种细胞类型重编程为另一种细胞类型的能力。对于细胞重编程重要的基因通常位于封闭的染色质中，被核小体覆盖。先锋因子是一类特殊的TFs，可以在接触之前将其目标位点接合在封闭的染色质中，打开,或其他因素对网站的修改。尽管在动物中已知许多先驱因素，一些在植物中具有特征。TFLEAFY（LFY）是指定拟南芥花命运的先驱因子。为了响应内源性和环境线索，植物产生适当的花卉诱导剂（florigens）。在植物生长阶段,LFY被终端花1（TFL1）-FD复合物抑制，作为一种花卉抑制剂，或者反Florigen.florigenen花斑点T（FT）与TFL1竞争以防止FDTF与LFY基因座的结合。所产生的FT-FD复合物用作激活其目标的瞬时刺激。一旦LFY以适当的时空方式转录，LFY与闭合染色质区域中的核小体结合。随后，LFY通过置换H1接头组蛋白并募集SWI/SNF染色质-重塑复合物来打开染色质。这种本地更改允许绑定其他TF，导致花分生组织同一性基因APETALA1的表达。这篇小型评论描述了我们对先驱TFLFY的理解的最新进展，通过植物表观遗传景观的塑造，提供对建立基因表达能力的见解。
