Sugar-inducible expression of the nucleolin-1 gene of Arabidopsis thaliana and its role in ribosome synthesis, growth and development
Sugar-inducible expression of the nucleolin-1 gene of Arabidopsis thaliana and its role in ribosome synthesis, growth and development
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DOI：
10.1111/j.1365-313x.2006.03016.x
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发表时间：
2007-03-01
期刊：
影响因子：
7.2
通讯作者：
Nakamura, Kenzo
中科院分区：
文献类型：
--
作者：
Kojima, Hisae;Suzuki, Takamasa;Nakamura, Kenzo
动物和酵母核仁素作为核糖体合成的全局调节剂，其表达与细胞增殖密切相关。虽然拟南芥含有两个核仁素基因，但AtNuc-L1是大多数组织中发现的蛋白质的主要形式，并且GFP-AtNuc-L1融合蛋白靶向核仁。AtNuc-L1的表达强烈诱导蔗糖或葡萄糖，但不是由非代谢甘露醇或2-脱氧葡萄糖。蔗糖还引起C/D和H/ACA小核仁核糖核蛋白亚基的基因表达增强，以及大量的核糖体蛋白（RP）基因，表明碳水化合物的可用性调节从头核糖体合成。在糖饥饿的细胞中，AtNuc-L1的诱导在10 mM葡萄糖下发生，这似乎是恢复生长的先决条件。AtNuc-L1的破坏导致前rRNA相对于成熟的25 S rRNA的稳态水平增加，并导致与几种RP基因突变体报道的表型重叠的各种表型，包括生长速率降低、寿命延长、浓密生长、尖叶和有缺陷的脉管模式和豆荚发育。这些结果表明，分生组织中核糖体的合成速率不仅对植物的生长而且对植物的结构具有强烈的影响。AtNuc-L1破坏剂表现出显着降低糖诱导的RP基因的表达，表明AtNuc-L1参与糖诱导的RP基因的表达。
Animal and yeast nucleolin function as global regulators of ribosome synthesis, and their expression is tightly linked to cell proliferation. Although Arabidopsis contains two genes for nucleolin, AtNuc-L1 is the predominant if not only form of the protein found in most tissues, and GFP-AtNuc-L1 fusion proteins were targeted to the nucleolus. Expression of AtNuc-L1 was strongly induced by sucrose or glucose but not by non-metabolizable mannitol or 2-deoxyglucose. Sucrose also caused enhanced expression of genes for subunits of C/D and H/ACA small nucleolar ribonucleoproteins, as well as a large number of genes for ribosomal proteins (RPs), suggesting that carbohydrate availability regulates de novo ribosome synthesis. In sugar-starved cells, induction of AtNuc-L1 occurred with 10 mM glucose, which seemed to be a prerequisite for resumption of growth. Disruption of AtNuc-L1 caused an increased steady-state level of pre-rRNA relative to mature 25S rRNA, and resulted in various phenotypes that overlap those reported for several RP gene mutants, including a reduced growth rate, prolonged lifetime, bushy growth, pointed leaf, and defective vascular patterns and pod development. These results suggest that the rate of ribosome synthesis in the meristem has a strong impact not only on the growth but also the structure of plants. The AtNuc-L1 disruptant exhibited significantly reduced sugar-induced expression of RP genes, suggesting that AtNuc-L1 is involved in the sugar-inducible expression of RP genes.