Jacob Yannick, Mongkolsiriwatana Chareerat, Veley Kira M, Kim Sang Yeol, Michaels Scott D
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Plant Physiol. 2007 Jul;144(3):1383-90. doi: 10.1104/pp.107.100735. Epub 2007 May 25.
Nuclear pore complexes (NPCs) mediate the transport of RNA and other cargo between the nucleus and the cytoplasm. In vertebrates, the NPC protein TRANSLOCATED PROMOTER REGION (TPR) is associated with the inner filaments of the nuclear basket and is thought to serve as a scaffold for the assembly of transport machinery. In a screen for mutants that suppress the expression of the floral inhibitor FLOWERING LOCUS C, we identified lesions in the Arabidopsis (Arabidopsis thaliana) homolog of TPR (AtTPR). attpr mutants exhibit early-flowering and other pleiotropic phenotypes. A possible explanation for these developmental defects is that attpr mutants exhibit an approximately 8-fold increase in nuclear polyA RNA. Thus AtTPR is required for the efficient export of RNA from the nucleus. Microarray analysis shows that, in wild type, transcript abundance in the nuclear and total RNA pools are highly correlated; whereas, in attpr mutants, a significantly larger fraction of transcripts is enriched in either the nuclear or total pool. Thus AtTPR is required for homeostasis between nuclear and cytoplasmic RNA. We also show that the effects of AtTPR on small RNA abundance and auxin signaling are similar to that of two other NPC-associated proteins, HASTY (HST) and SUPPRESSOR OF AUXIN RESISTANCE3 (SAR3). This suggests that AtTPR, HST, and SAR3 may play related roles in the function of the nuclear pore.
核孔复合体（NPCs）介导RNA和其他物质在细胞核与细胞质之间的运输。在脊椎动物中，NPC蛋白转位启动子区域（TPR）与核篮的内部细丝相关联，并被认为是运输机制组装的支架。在筛选抑制花抑制因子开花位点C表达的突变体时，我们在拟南芥（Arabidopsis thaliana）TPR（AtTPR）的同源物中发现了损伤。attpr突变体表现出早花和其他多效性表型。对这些发育缺陷的一种可能解释是，attpr突变体的核多聚腺苷酸RNA增加了约8倍。因此，AtTPR是RNA从细胞核有效输出所必需的。微阵列分析表明，在野生型中，核RNA池和总RNA池中的转录本丰度高度相关；而在attpr突变体中，显著更大比例的转录本在核池或总池中富集。因此，AtTPR是核与细胞质RNA之间稳态所必需的。我们还表明，AtTPR对小RNA丰度和生长素信号传导的影响与另外两种与NPC相关的蛋白，即速激肽（HST）和生长素抗性3抑制因子（SAR3）相似。这表明AtTPR、HST和SAR3可能在核孔功能中发挥相关作用。
