Role of MRG15 in Chromatin Changes During Cell Senescence and In Vivo Aging

本项目的总体目标是阐明染色质重塑在体外和体内过程中的作用， 衰老越来越清楚的是，染色质重塑是基因表达所必需的 调节和组织DNA结构以允许修复DNA损伤。MRG 15，这显然是 参与染色质重塑的各个方面，因此作为一个很好的模型基因， 研究染色质结构的变化对基因表达和DNA修复的重要性， 老化过程MRG 15是在我们实验室研究细胞衰老的过程中克隆的， 表达的MORF/MRG基因家族的三个成员。它与MORF 4共享共同的基序 和包括亮氨酸拉链、HLH区和核定位信号序列的MRGX， 推测这些蛋白质将通过蛋白质-蛋白质相互作用参与转录调控。然而，在这方面， 只有MRG 15的N-末端结构域是一个色结构域基序，这与ms！3 (male果蝇的一种特异性致死）基因，该基因是激活整个X染色体转录所必需的 染色体的雄性果蝇，剂量补偿机制。这个染色体结构域现在已经被 作为Tip 60组蛋白乙酰转移酶的一个组成部分，MRG 15的募集是必需的 复杂到染色质重塑必须发生的位点。这包括转录的区域 激活是要发生的，也是受损DNA的位点。染色质重塑先于 参与转录或DNA修复的核蛋白复合物。MRG 15是一种高度保守的蛋白质， 存在于人类的酵母中。它所结合的复合物的蛋白质成分也是高度 保守的因此，小鼠或果蝇中该基因的缺失导致胚胎发育并不奇怪 道德在这项提议中，我们计划确定MRG 15在细胞增殖控制和DNA合成中的作用。 使用两种细胞培养系统，年轻和年老的C57 BI 6小鼠和MRG 15杂合子小鼠， 小鼠模型我们将描述所涉及的各种蛋白质复合物，它们在体外和体外过程中的变化， 体内老化以及这些变化对细胞和组织功能的影响。结果不仅将平局 结合体外和体内的信息，也增加了我们对核蛋白如何以及何时 复合物起作用，并更好地定义了衰老过程中染色质重塑的作用。

The overall goal of this project is to elucidate the role of chromatin remodeling during in vitro and in vivo aging. It is becoming increasingly clear that chromatin remodeling is essential for gene expression regulation and organization of DMA structure to allow for repair of DNA damage. MRG15, which is clearly involved in various aspects of chromatin remodeling, therefore serves as an excellent model gene for the study of the importance of changes in chromatin structure on gene expression and DNA repair during the aging process. MRG15 was cloned in our laboratory in the course of our studies of cellular aging, as one of three members of the MORF/MRG family of genes that is expressed. It shares common motifs with MORF4 and MRGX that include a leucine zipper, HLH region and nuclear localization signal sequences, which uggest these proteins will be involved in transcriptional regulation via protein-protein interactions. However, n the N-terminal domain of only MRG15 is a chromodomain motif, which is highly similar to that in the ms!3 (male specific lethal) gene of Drosophila, which is required for activation of transcription of the entire X chromosome in male flies, the dosage compensation mechanism. This chromodomain has now been mplicated as essential for recruitment of MRG15 as a component of the Tip60 histone acetyltranserase complex to sites where chromatin remodeling must occur. This includes regions where transcription activation is to occur and also sites of damaged DNA. Chromatin remodeling precedes the recruitment of nuclear protein complexes involved in transcription or DNA repair. MRG15 is a highly conserved protein and s present in yeast to human. The protein components of the complexes it associates with are also highly conserved. It is therefore not surprising that deletion of this gene in mice or Drosophila results in embryonic ethality. In this proposal we plan to determine the role of MRG15 in cell proliferation control and DNA damage repair using both cell culture systems, young and old C57BI6 mice and the MRG15 heterozygous mouse model. We will characterize the various protein complexes involved, their changes during in vitro and n vivo aging and the impact of these changes on function of cells and tissues. The results will not only tie ogether in vitro and in vivo information, but also increase our knowledge of how and when nuclear protein omplexes act and better define the role of chromatin remodeling during aging.