Mutation of RNA Pol III subunit rpc2/polr3b Leads to Deficiency of Subunit Rpc11 and disrupts zebrafish digestive development.
Mutation of RNA Pol III subunit rpc2/polr3b Leads to Deficiency of Subunit Rpc11 and disrupts zebrafish digestive development.
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DOI：
10.1371/journal.pbio.0050312
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发表时间：
2007-11
期刊：
影响因子：
9.8
通讯作者：
Pack M
中科院分区：
文献类型：
--
作者：
Yee NS;Gong W;Huang Y;Lorent K;Dolan AC;Maraia RJ;Pack M
RNA聚合酶III(POL III)在脊椎动物发育中的作用还没有被研究过。在这里，我们发现了第二大POLIII亚基polr3b的一个致病突变，它扰乱了斑马鱼Slim Jim(SLJ)突变体的消化器官发育。SLJ突变是一种剪接位替换，导致Polr3b蛋白中41个氨基酸的保守区缺失。结构方面的考虑预测，SLJ Pol3rb的缺失可能会损害它与Polr3k的相互作用，Polr3k是酵母基本的PolIII亚基Rpc11的同源基因，它促进RNA切割和PolIII循环。我们对裂殖酵母进行了改造，使其携带与SLJ突变类似的RPC2缺失，并发现从这种rPC2-Δ酵母中回收的POLIII显著降低了RPC11P的水平。值得注意的是，斑马鱼rpc11同源基因polr3k的过表达挽救了SLJ突变体的外分泌缺陷，表明SLJ表型是由于Rpc11的缺失所致。这些数据表明，POL III亚基之间的功能相互作用在真核生物进化过程中是保守的，并支持斑马鱼作为模式脊椎动物用于分析POL III功能。遗传信息从DNA到信使RNA再到蛋白质的传递依赖于大量非编码小RNA分子的功能。编码这些RNA的基因是由RNA聚合酶III(Pol III)转录的，Pol III是一个17个亚基的蛋白质复合体，其结构与RNA聚合酶I和RNA聚合酶II的结构密切相关。在这里，我们报道了编码一个Pol III亚单位Polr3b的基因突变对斑马鱼消化系统组织祖细胞的增殖和生长的影响。对编码Polr3b的酵母链霉菌基因的一个几乎相同的突变的分析表明，斑马鱼的突变破坏了突变的Polr3b蛋白与另一个Pol III亚基Polr3k的相互作用，Polr3k也被称为Rpc11。Polr3b突变体中Polr3k编码基因的过表达部分挽救(逆转)了突变表型。这些发现扩大了我们对POL III功能机制的了解，在真核进化过程中，POL III功能似乎是高度保守的。此外，这些数据还表明，17亚基Pol III酶的组装是一个动态过程，因为Polr3k的过度表达可以部分挽救突变的表型。了解Pol III是如何组装的对人类疾病具有重要意义，因为Pol III在大多数癌症中的活性显著增加。RNA聚合酶III转录tRNAs和其他非编码RNA对于细胞的增殖、生长和存活是必不可少的。在分裂酵母S.pombe的实验帮助下，作者报道了第二大Pol III亚基Polr3b的框内小片段缺失如何影响斑马鱼发育中的消化系统的组织祖细胞。
The role of RNA polymerase III (Pol III) in developing vertebrates has not been examined. Here, we identify a causative mutation of the second largest Pol III subunit, polr3b, that disrupts digestive organ development in zebrafish slim jim (slj) mutants. The slj mutation is a splice-site substitution that causes deletion of a conserved tract of 41 amino acids in the Polr3b protein. Structural considerations predict that the slj Pol3rb deletion might impair its interaction with Polr3k, the ortholog of an essential yeast Pol III subunit, Rpc11, which promotes RNA cleavage and Pol III recycling. We engineered Schizosaccharomyces pombe to carry an Rpc2 deletion comparable to the slj mutation and found that the Pol III recovered from this rpc2-Δ yeast had markedly reduced levels of Rpc11p. Remarkably, overexpression of cDNA encoding the zebrafish rpc11 ortholog, polr3k, rescued the exocrine defects in slj mutants, indicating that the slj phenotype is due to deficiency of Rpc11. These data show that functional interactions between Pol III subunits have been conserved during eukaryotic evolution and support the utility of zebrafish as a model vertebrate for analysis of Pol III function. The transmission of genetic information from DNA to messenger RNA to protein depends on the function of a large number of small noncoding RNA molecules. The genes encoding these RNAs are transcribed by RNA polymerase III (Pol III), a 17-subunit protein complex whose structure is closely related to that of RNA polymerases I and II. Here, we report the effect of a mutation in a gene encoding one Pol III subunit, Polr3b, which disrupts proliferation and growth of tissue progenitor cells in the zebrafish digestive system. Analyses of a nearly identical mutation in the yeast S. pombe gene encoding Polr3b, also known as Rpc2, suggested that the zebrafish mutation disrupted the mutant Polr3b protein's interaction with another Pol III subunit, Polr3k, also known as Rpc11. Overexpression of the gene encoding Polr3k in the Polr3b mutants partially rescued (reversed) the mutant phenotype. These findings extend our knowledge of the mechanism of Pol III function, which appears to have been highly conserved during eukaryotic evolution. Furthermore, these data also suggest that assembly of the 17-subunit Pol III enzyme is a dynamic process, since Polr3k overexpression can partially rescue the mutant phenotype. Understanding how Pol III is assembled has implications for human disease, since Pol III activity is markedly increased in most cancers. Transcription of tRNAs and other noncoding RNAs by RNA polymerase III is essential for cell proliferation, growth, and survival. With the aide of experiments in the fission yeast,S. pombe, the authors report how a small in-frame deletion in the second largest Pol III subunit, Polr3b, affects tissue progenitor cells in the developing zebrafish digestive system.
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