Ohtani Misato, Demura Taku, Sugiyama Munetaka
Plant Science Center, RIKEN, Yokohama 230-0045, Japan.
Plant Mol Biol. 2008 Feb;66(3):303-14. doi: 10.1007/s11103-007-9271-7. Epub 2007 Dec 7.
Small nuclear RNA (snRNA) is a class of eukaryotic noncoding RNAs, which have essential roles in pre-mRNA splicing and rRNA processing. As these functions are fundamental to cell activities, the regulation of snRNA transcription should be a vital issue for all eukaryotes. Here we address developmental control of snRNA transcription and its significance through the analysis of the SRD2 gene of Arabidopsis (Arabidopsis thaliana), which encodes an activator of snRNA transcription. In young seedlings, a high level of SRD2 expression was observed in shoot and root apical meristems, leaf primordia, and root stele tissues, where a large amount of snRNA accumulated. In mature plants, SRD2 was highly expressed in developing leaves and flowers as well as apical meristems. Mutations in the SRD2 gene interfered with many, but not all, aspects of development in the regions that showed strong expression of SRD2. Of note, establishment of the fully active state of apical meristems in the seedling stage was very sensitive to the srd2-1 mutation, while maintenance of the established meristems was substantially insensitive. These results demonstrated differential requirement for the SRD2 function in various stages of plant development.
小核RNA（snRNA）是一类真核生物非编码RNA，在mRNA前体剪接和rRNA加工过程中发挥着重要作用。由于这些功能对细胞活动至关重要，snRNA转录的调控对于所有真核生物来说都应该是一个至关重要的问题。在这里，我们通过对拟南芥（Arabidopsis thaliana）的SRD2基因进行分析，探讨snRNA转录的发育调控及其意义，该基因编码一种snRNA转录激活因子。在幼苗中，在茎尖和根尖分生组织、叶原基和根中柱组织中观察到高水平的SRD2表达，这些部位积累了大量的snRNA。在成熟植株中，SRD2在发育中的叶片、花朵以及顶端分生组织中高表达。SRD2基因突变干扰了SRD2表达强烈区域的许多（但不是全部）发育过程。值得注意的是，幼苗期顶端分生组织完全活跃状态的建立对srd2-1突变非常敏感，而对已建立的分生组织的维持则基本不敏感。这些结果表明，在植物发育的不同阶段对SRD2功能有不同的需求。
