RNA METABOLISM IN NORMAL AND MALIGNANT GROWTH

我们早先的结果表明，紫外线辐射目标的大小 人类U1小核RNA(SnRNA)转录可能非常大， 可能多达4-5千碱基，尽管U1 RNA只有165个核苷酸 长。因此，U1 RNA可能被合成为非常 必须考虑长期的前身。人核RNA凝胶的分析 Blots，我们检测到最近短命的大转录本(a 平均大小为几千个碱基的异分散布居) 与U1 DNA有序列同源性。我们的主要具体目标是找出 包含U1类序列的大转录本是什么？这 包括确定它们的结构是否与U1 RNA相容 前体(例如：它们是否含有完整的全长U1 RNA 序列？)。下一个目标是绘制这些大型文本和 描述它们的非U1区域。这包括：a)将 这些转录本在人类基因组U1基因座上的大致末端由 核酸酶S1保护试验；b)RNA-DNA杂交物的电子显微镜 在富含类U1序列的大转录本之间形成并克隆 人类U1基因座的DNA片段；c)确定这些大的 转录本包含与任何丰富的序列同源的区域 除U1基因两侧的片段外的人类基因组；以及d)检查 这些大转录本的非U1序列在活体中的命运 手机。如果前面的实验结果与 这些大的转录本是U1 SnRNA的前体，这将是有趣的 检查：a)它们是否由包含以下内容之一的结构设置上限 7-单甲基鸟苷或N_2，N，7-三甲基鸟苷；以及b)一些代谢 这些大的成绩单的各个方面(例如： 带有U1样序列的长转录本，与外观相比较 新合成的U1单链RNA)。另一个目标是描述相对的 我们最近检测到的大量具有序列的小RNA 与位于紧邻其上游的高度保守区域同源 人类U1基因。我们已经证明了人类U3和U4的生物合成 除了U1和U2 RNA外，SnRNA对紫外线非常敏感 辐射。下一个目标是找出是否有很长的成绩单 可以检测到类似U2、U3或U4 RNA的序列。自.以来 这个项目将产生关于人类表达的基本信息 基因组，它的主要医学联系是遗传疾病的研究 和肿瘤。

Our earlier results suggested that the ultraviolet radiation target size of human U1 small nuclear RNA (snRNA) transcription may be very large, possibly as much as 4-5 kilobases, although U1 RNA is only 165 nucleotides long. Therefore, the possibility that U1 RNA might be synthesized as very long precursors had to be considered. Analyzing human nuclear RNA gel blots, we have detected recently short-lived large transcripts (a heterodisperse population with an average size of several kilobases) which have sequence homology to U1 DNA. Our major specific aim is to find out what are the large transcripts that contain U1-like sequences. This involves determining if their structure is compatible with being U1 RNA precursors (e.g.: do they contain perfect, full-length U1 RNA sequences?). The next goal is to map these large transcripts and characterize their non-U1 regions. This includes: a) mapping the approximate ends of these transcripts on human genome U1 loci by the nuclease S1 protection assay; b) electron microscopy of RNA-DNA hybrids formed between large transcripts enriched for U1-like sequences and cloned DNA fragments of human U1 gene loci; c) determining if these large transcripts contain regions with homology to any abundant sequence of the human genome other than the segments flanking U1 genes; and d) examining the fate of the non-U1 sequences of these large transcripts in the living cell. If the results from the preceding experiments are compatible with these large transcripts being U1 snRNA precursors, it would be interesting to examine: a) if they are capped by structures that contain either 7-monomethylguanosine or N2,N2,7-trimethylguanosine; and b) some metabolic aspects of these large transcripts (e.g.: the kinetics of disappearance of long transcripts bearing U1-like sequences, in comparison to the appearance of newly made U1 snRNA). Another goal is to characterize the relatively abundant small RNAs that we have detected recently, that have sequence homology to the highly conserved region located immediately upstream from human U1 genes. We have shown that the biosynthesis of human U3 and U4 snRNA, in addition to that of U1 and U2 RNA, is very sensitive to UV radiation. The next goal is to find out if long transcripts bearing sequences like those of either U2, U3 or U4 RNA can be detected. Since this project will yield basic information about the expression of the human genome, its major medical connection is to the study of genetic diseases and neoplasias.