RNA METABOLISM IN NORMAL AND MALIGNANT GROWTH

我们早期的研究结果表明，紫外线辐射的目标大小， 人U1小核RNA（snRNA）转录可能非常大， 尽管U1 RNA只有165个核苷酸，但可能多达4-5个碱基， 久了 因此，U1 RNA合成的可能性非常小。 必须考虑长的前体。 分析人核RNA凝胶 印迹，我们已经检测到最近短暂的大转录本（a 平均大小为几千个碱基的异分散群体）， 与U1 DNA序列同源。 我们的主要目标是找出 含有U1样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： 它们是否含有完美的全长U1 RNA 序列？）。 下一个目标是绘制这些大型转录本， 描述他们的非U1区。 这包括： a）映射 在人类基因组U1基因座上的这些转录物的近似末端， 核酸酶S1保护测定; B）RNA-DNA杂交体的电子显微镜检查 在富含U1样序列的大转录本之间形成， 人U1基因座的DNA片段; c）确定这些大的 转录本含有与任何丰富的转录本序列同源的区域。 除了U1基因侧翼的区段之外的人类基因组;以及d）检查 这些大转录本的非U1序列在活体中的命运 cell. 如果前面实验的结果与 这些大的转录本是U1 snRNA的前体， 检查：a）它们是否被包含以下内容的结构所覆盖： 7-单甲基鸟苷或N2，N2，7-三甲基鸟苷;和B）一些代谢产物 这些大型转录本的各个方面（例如： 消失的动力学 长转录本携带U1样序列，与外观相比， 新的U1 snRNA）。 另一个目标是描述 我们最近检测到大量的小RNA， 同源性的高度保守的区域位于紧接上游 人类U1基因。 我们已经证明，人类U3和U4的生物合成 除了U1和U2 RNA外，snRNA对UV非常敏感 辐射 下一个目标是找出是否长成绩单轴承 可以检测到类似于U2、U3或U4 RNA的序列。 以来 这个项目将产生关于人类表达的基本信息， 基因组，其主要的医学联系是对遗传疾病的研究 和肿瘤形成。

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.