Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain.
Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860, Perpignan, France.
Plant Cell. 2018 Nov;30(11):2855-2872. doi: 10.1105/tpc.18.00245. Epub 2018 Oct 25.
Ribosome biogenesis is fundamental to growth and development in eukaryotes and is linked to human diseases and cancer. MORPHOLOGY OF ARGONAUTE1-52 SUPPRESSED 2 (MAS2) participates in splicing and 45S ribosomal DNA (rDNA) expression. In a screen for MAS2 interactors, we identified RIBOSOMAL RNA PROCESSING 7 (RRP7), an ortholog of yeast rRNA processing protein 7 (Rrp7), which is required for 18S ribosomal RNA (rRNA) maturation. Arabidopsis mutants exhibit a pleiotropic phenotype including slow growth, altered shoot phyllotaxy, aberrant venation in lateral organs, partial infertility, and abscisic acid hypersensitivity in seedlings. In Arabidopsis, RRP7 localizes mainly to the nucleolus, the site of the 45S rDNA transcription that produces a 45S pre-rRNA primary transcript, precursor of the 25S, 18S and 5.8S rRNAs. Lack of RRP7 function perturbs 18S rRNA maturation, causes nucleolar hypertrophy, and results in an increased 25S/18S rRNA ratio. Arabidopsis contains hundreds of 45S rDNA genes whose expression is epigenetically regulated, and deregulated, in mutants. Double mutant analysis revealed synergistic interactions between alleles and alleles of , (), and (), which encode epigenetic regulators of 45S rDNA transcription. Our results reveal the evolutionarily conserved but divergent roles of RRP7 as a ribosome biogenesis factor.
核糖体生物发生对于真核生物的生长和发育至关重要，并且与人类疾病和癌症有关。ARGONAUTE1-52 SUPPRESSED 2 (MAS2) 的形态参与剪接和 45S 核糖体 DNA (rDNA) 表达。在 MAS2 相互作用蛋白的筛选中，我们鉴定了 RIBOSOMAL RNA PROCESSING 7 (RRP7)，它是酵母 rRNA 加工蛋白 7 (Rrp7) 的同源物，是 18S 核糖体 RNA (rRNA) 成熟所必需的。拟南芥 突变体表现出多种表型，包括生长缓慢、茎生叶排列改变、侧生器官叶脉异常、部分不育和幼苗对脱落酸的超敏反应。在拟南芥中，RRP7 主要定位于核仁，这是 45S rDNA 转录的部位，产生 45S 前 rRNA 初级转录本，是 25S、18S 和 5.8S rRNAs 的前体。RRP7 功能缺失会扰乱 18S rRNA 的成熟，导致核仁肥大，并导致 25S/18S rRNA 比值增加。拟南芥含有数百个 45S rDNA 基因，其表达受表观遗传调控，并在 突变体中失调。双突变体分析显示， 等位基因和 等位基因之间存在协同相互作用， （），和 （），它们编码 45S rDNA 转录的表观遗传调节剂。我们的研究结果揭示了 RRP7 作为核糖体生物发生因子的进化保守但又不同的作用。
