MECHANISMS OF CELLULAR IMMORTALIZATION

细胞永生化机制

• 批准号: 6637786
• 负责人: Woodring Erik Wright
• 金额: $ 49.2万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-04-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6637786
• 关键词: DNA binding protein; DNA damage; DNA directed DNA polymerase; aging; biological signal transduction; cell cycle; cell line; cell senescence; deoxyribonuclease I; enzyme activity; gene expression; genetic regulatory element; heterochromatin; messenger RNA; neoplastic transformation; oncoproteins; polymerase chain reaction; posttranscriptional RNA processing; protein structure function; protooncogene; site directed mutagenesis; telomerase; telomere; transcription factor; transfection /expression vector

Normal diploid human somatic cells have a limited capacity to proliferate, a process termed replicative senescence. Increasing evidence over the last decade has implicated telomeres, the structures that cap the ends of the chromosomes, as the molecular clock that counts the number of times the cell has divided The mechanism of lagging strand DNA synthesis prevents DNA polymerase from replicating the DNA all the way to the 3' end of a linear chromosome, causing the chromosomes to shorten every time a cell divides. Human telomeres prevent the cell from recognizing the end of the chromosome as a DNA break needing repair. In yeast, telomere length can influence the expression of adjacent genes (telomere positional effects). Cellular senescence may occur when some of the telomeres have shortened sufficiently to induce a DNA damaged signal, or when the expression of regulatory loci in the subtelomeric DNA changes and induces a growth arrest program. Cellular immortalization is usually accompanied by the reactivation of the enzyme telomerase, which is able to add telomeric repeats to the ends of the chromosomes and thus prevent their shortening. This proposal consists of two braid aims. Aim 1 is directed towards understanding the molecular basis for the regulation of telomerase. We will determine the mechanism by which it is reactivated by identifying members of the repressive pathway those inactivation permits the re- expression of the mRNA for the telomerase catalytic subunit. We will also study the telomerase gene and how factors that positively regulate expression such as c-Myc alter its chromatin structure. Aim 2 pursues the signal transduction mechanism by which telomere shortening affects cell behavior, and will developing evidence for or against the presence of telomere position effects in human cells. The information resulting from these studies should help define the molecular mechanisms underlying replicative senescence and its relationship to cancer.

正常的二倍体人体细胞的增殖能力有限，该过程称为复制衰老。 Increasing evidence over the last decade has implicated telomeres, the structures that cap the ends of the chromosomes, as the molecular clock that counts the number of times the cell has divided The mechanism of lagging strand DNA synthesis prevents DNA polymerase from replicating the DNA all the way to the 3' end of a linear chromosome, causing the chromosomes to shorten every time a cell divides.人端粒阻止细胞识别染色体的末端，因为需要修复的DNA断裂。在酵母中，端粒长度可以影响相邻基因的表达（端粒位置效应）。当一些端粒缩短以诱导DNA损坏的信号，或者在亚电体DNA中的调节基因座的表达变化并诱导生长停滞计划时，可能会发生细胞衰老。细胞永生化通常伴随着酶​​端粒酶的重生，该酶能够在染色体的末端增加端粒重复序列，从而防止其缩短。该提议包括两个辫子目标。 AIM 1致力于理解端粒酶调节的分子基础。我们将通过识别抑制性途径的成员来确定其被重新激活的机制，这些途径允许对端粒酶催化亚基的mRNA表达。我们还将研究端粒酶基因以及如何积极调节表达（例如C-MYC）改变其染色质结构的因素。 AIM 2追求端粒缩短影响细胞行为的信号转导机制，并将为人类细胞中端粒位置效应的存在而开发证据。这些研究产生的信息应有助于定义复制性衰老的基本分子机制及其与癌症的关系。