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

这个项目的总体目标是阐明染色质重塑在体外和体内的作用。 衰老。越来越清楚的是，染色质重塑对基因表达是必不可少的 调节和组织DNA结构，以修复DNA损伤。MRG15，这显然是 参与染色质重塑的各个方面，因此是一种很好的模型基因 染色质结构变化对基因表达和DNA修复影响的研究 老化过程。MRG15是本实验室在细胞衰老研究过程中克隆的 表达的Morf/MRG基因家族中的三个成员。它与MORF4有共同的主题 和包括亮氨酸拉链、HLH区和核定位信号序列的MRGX，其 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， 只有MRG15的N-末端结构域是一个色域基序，这与MS！3中的高度相似 果蝇(雄性特异性致死)基因，激活整个X基因转录所必需的 雄蝇染色体的剂量补偿机制。这个色域现在已经被 作为Tip60组蛋白乙酰转移酶组成部分的MRG15的招募所必需的 复杂到必须发生染色质重塑的部位。这包括转录的区域 激活也会发生，DNA受损的部位也会发生。染色质重塑先于重新招募 参与转录或DNA修复的核蛋白复合体。MRG15是一种高度保守的蛋白质 S以酵母的形式存在于人类体内。与之相关的复合体的蛋白质成分也高度 保守的。因此，在小鼠或果蝇中缺失这种基因就不足为奇了，这会导致胚胎 伦理道德。在这项提案中，我们计划确定MRG15在细胞增殖控制和DNA中的作用 用两种细胞培养系统修复损伤，年轻和老年C57BI6小鼠和MRG15杂合子 老鼠模型。我们将表征涉及的各种蛋白质复合体，它们在体外和体外的变化 体内衰老以及这些变化对细胞和组织功能的影响。结果不仅是平局 在体外和体内的信息聚集在一起，也增加了我们对核蛋白如何以及何时的了解 复合体在衰老过程中起作用并更好地定义染色质重塑的作用。

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.