Ohtani Misato, Sugiyama Munetaka
Botanical Gardens, Graduate School of Science, The University of Tokyo, 3-7-1 Hakusan, Bunkyo-ku, Tokyo 112-0001, Japan.
Plant J. 2005 Aug;43(4):479-90. doi: 10.1111/j.1365-313X.2005.02469.x.
The transcription machinery of small nuclear RNA (snRNA) genes has been investigated extensively in human cell-free systems, but its physiological function in vivo has not been addressed. This paper demonstrates the physiological role of an activator of snRNA transcription using a temperature-sensitive mutant of Arabidopsis thaliana, srd2. Phenotypic characteristics of the srd2 mutant suggest that the SRD2 gene participates in the control of competence in cell proliferation. The SRD2 gene encodes a nuclear protein that shares sequence similarity with the human SNAP50 protein, which is a subunit of SNAPc and is required for snRNA transcription in vitro. Our results, obtained from analysis of snRNA expression in the srd2 mutant, indicate that the SRD2 protein functions in the upregulation of transcription of snRNA genes, the promoters of which contain the upstream sequence element, to elevate cell proliferation competence.
小核RNA（snRNA）基因的转录机制已在人类无细胞系统中得到广泛研究，但其在体内的生理功能尚未得到探讨。本文利用拟南芥的一个温度敏感突变体srd2，证明了snRNA转录激活因子的生理作用。srd2突变体的表型特征表明，SRD2基因参与细胞增殖能力的调控。SRD2基因编码一种核蛋白，该蛋白与人类SNAP50蛋白具有序列相似性，SNAP50蛋白是SNAPc的一个亚基，在体外snRNA转录中是必需的。我们通过分析srd2突变体中snRNA的表达所获得的结果表明，SRD2蛋白在snRNA基因转录上调中发挥作用，这些基因的启动子包含上游序列元件，以提高细胞增殖能力。
