Synthesis, Structure, and Function of Eukaryotic U14 snRNA

真核小核rna （snrna）在信使前rna和核糖体前rna的加工过程中起着关键作用。其中一种被称为U14 snRNA的核仁snRNA对核糖体前RNA的加工至关重要。真菌、两栖动物和哺乳动物U14 snRNA与18SrRNA分子间碱基对的进化保守性表明，这种氢键相互作用在U14 snRNA功能和核糖体RNA加工事件中很重要。我们已经证明，小鼠U14 snRNA基因位于组成性表达的同源hsc70热休克基因的内含子5,6和8中，这一定位导致实验证实存在U14 snRNA产生的内含子加工途径。这是真核前mrna内含子被加工成稳定的、具有生物学功能的RNA物种的第一个例子。我们将继续表征U14 snRNA的合成、结构和功能，同时探索这些参数的进化守恒。U14 snRNA切除所必需的加工序列/结构将由几种不同的方法确定。我们将检测非洲爪蟾U14 snRNA/hsc70 pre- mRNA在发育中的表达。我们将在进化多样的真核生物中研究U14 snRNA基因的基因组组织。在同一过程中，RNA既用作蛋白质合成的结构分子，也用作信使分子。较小的RNA种类已被发现对核糖体和信使RNA的正确合成至关重要，其中一些已被分离和表征。U14 snRNA就是这样一种分子，但它的独特之处在于，该实验室发现它位于另一个基因hsc70热休克基因的内含子中。这是内含子被加工成稳定的、具有生物学功能的RNA物种的第一个例子。U14 snRNA的产生过程以及该RNA物种的发育表达和进化保护将得到更广泛的研究。＊＊＊

9304672 Maxwell Eukaryotic small nuclear RNAs(snRNAs) play critical roles in the processing of both pre-messenger and pre-ribosomal RNAs. One such nucleolar snRNA designated U14 snRNA is essential for the processing of pre-ribosomal RNA. The evolutionarily conserved ability of fungal, amphibian and mammalian U14 snRNAs to intermolecularly base-pair with 18SrRNA suggests that this hydrogen-bonding interaction is important in U14 snRNA function and ribosomal RNA processing events. We have demonstrated that the mouse U14 snRNA genes are located within introns 5,6 and 8 of the constitutively-expressed cognate hsc70 heat shock gene, a positioning which led to experiments confirming that an intron- processing pathway for U14 snRNA production exists. This is the first example of a eukaryotic pre-mRNA intron which is processed to yield a stable, biologically functional RNA species. We will continue characterizing U14 snRNA synthesis, structure and function while exploring the evolutionary conservation of those parameters. The processing sequences/structures essential for U14 snRNA excision will be determined by several different approaches. We will examine the developmental expression of U14 snRNA/hsc70 pre- mRNA in Xenopus laevis. We will examine the genomic organization of U14 snRNA genes in evolutionarily diverse eukaryotic organisms. %%% RNA is utilized both as a structural molecule for protein synthesis as well as a messenger molecule in the same process. Smaller RNA species have been found to be essential to the correct synthesis of the ribosomal and messenger RNAs and a number of them have been isolated and characterized. U14 snRNA is one such molecule, but one which is unique in that it was found by this laboratory to be located in introns of another gene, the hsc70 heat shock gene. This is the first example of an intron which is processed to yield a stable, biologically functional RNA species. The process of producing the U14 snRNA will be studied more extensiv ely as well as the developmental expression and the evolutionary conservation of this RNA species. ***