DNA METHYLATION IN LYMPHOCYTES

甲基化和去甲基化已被提出多种作用。 真核DNA中的胞嘧啶。这些可能的角色包括：(1) 转录调控机制，(2)保护 来自破坏的特定DNA片段，(3)维护或丢失 病毒基因组在转化细胞和未转化细胞中的潜伏状态， (4)DNA合成起始的控制。在特定情况下 嗜淋巴的疱疹病毒，其中许多会引起肿瘤 在各种动物的淋巴系统中，有证据表明 DNA甲基化/去甲基化是这种转变的关键组成部分 在病毒生命周期的潜伏期和产生期之间。 在这里提出的工作中，转化的淋巴细胞感染了 疱疹病毒爱泼斯坦-巴尔将成为用于 确定DNA甲基化和去甲基化的机制。两者都像病毒一样 从这些细胞系中分离出的细胞DNA显示出高度可变的 许多CG部位的甲基化程度。我们建议在这里确定， 从它们中分离纯化甲基酶(DNA甲基转移酶) 淋巴细胞和可能的序列偏好、可变亲和力的测试 病毒和细胞DNA，以及这种活动是否由病毒诱导 或者被压抑。我们进一步建议开发三个独立的检测系统 确定在这些细胞中作用的脱甲基化机制(S)。

Various roles have been proposed for the methylation and demethylation of cytosines in eucaryotic DNA. These possible roles include: (1) a transcriptional control mechanism, (2) a modification system that protects specific pieces of DNA from destruction, (3) maintenance or loss of the latent state of viral genomes in both transformed and nontransformed cells, and (4) control of initiation of DNA synthesis. In the specific case of the lymphotropic herpesviruses, many of which generate tumors of the lymphatic system in a variety of animals, evidence has accumulated showing DNA methylation/demethylation to be a critical component of the shifts between latent and productive phases of the viral life cycle. In the work proposed here, transformed lymphocytes infected with the herpesvirus Epstein-Barr will be the experimental system employed to determine the mechanism of DNA methylation and demethylation. Both viral and cellular DNA isolated from these cell lines show highly variable degrees of methylation at many CG sites. We propose here to identify, isolate and purify methylases (DNA methyl transferases) from these lymphocytes and test for possible sequence preferences, variable affinities for viral and cellular DNA, and whether such activities are virally induced or repressed. We further propose to develop three separate assay systems to identify the DNA demethylating mechanism(s) operating within these cells.