Investigating the role of arginine methylation as a critical regulator of DNA replication and genome stability

细胞基因组的复制对于生命的延续至关重要，这必须以有效和适时的方式发生，以确保每个子细胞获得正确数量的遗传物质。在胚胎发育期间，细胞经历一段快速、高度协调的DNA复制，以产生足够数量的细胞来维持胚胎的生长。因此，在此期间，任何减缓基因组复制或细胞分裂的遗传性基因突变都会减少可用于胚胎发育的细胞总数，从而最终缩小胎儿和某些器官（如大脑）的大小。患有先天性遗传性疾病的儿童被诊断为小头原始侏儒症（MPD），这种疾病会限制儿童的生长并缩小头部/大脑尺寸。虽然MPD被归类为一种罕见的人类疾病，但对患有这种疾病的患者的研究表明，一种常见的潜在原因是编码蛋白质的基因发生遗传突变，这些蛋白质的功能是复制基因组。由此，已经假设胚胎发育期间DNA复制效率的降低阻止了在细胞分裂之前及时完成完整的基因组复制。这会对DNA产生损伤，从而引发DNA受损的细胞死亡。由于胚胎发育过程中细胞死亡增加，胎儿和几个器官系统的整体发育受到限制，从而导致患有MPD的儿童。因此，对罕见人类疾病（如MPD）的研究大大增加了我们对DNA复制等基本过程如何保护细胞免受累积遗传损伤以及当该过程失败时后果的了解。然而，尽管我们取得了进展，但我们仍然没有完全了解这些途径如何发挥作用的许多重要方面，或者是否存在尚未发现的其他因素。在这方面，我们已经确定了一种新的蛋白质，DONSON，它在MPD患者中发生突变，其功能是帮助细胞复制DNA，并在检测到DNA损伤时激活信号。然而，虽然DONSON基因突变似乎是MPD的一个相对常见的原因，但我们仍然不了解DONSON如何调节DNA复制，DONSON如何发出DNA损伤的信号，细胞如何指示DONSON执行其功能或为什么该基因的突变会导致MPD。我们的初步数据表明，DONSON的精氨酸甲基化对其促进DNA复制的能力至关重要，但我们对为什么这很重要的理解还很缺乏。因此，本提案的目的是研究DONSON的精氨酸甲基化如何控制DNA复制以及该过程中的缺陷如何促进疾病的发展。我们希望通过增加我们对DONSON功能及其调节方式的了解，我们对该疾病的更深入了解将通过更好的疾病管理和提高基因诊断能力使MPD患者受益。

Duplication of the cell's genome is essential for the continuation of life, and this must occur in an efficient and well-timed manner to ensure that each daughter cell gets the correct amount of genetic material. During embryonal development, cells undergo a period of rapid, highly coordinated DNA replication to produce sufficient numbers of cells to sustain growth of the embryo. Consequently, any inherited genetic mutation that slows genome duplication or cell division during this period reduces the total number of cells available for embryonal development, which ultimately reduces the size of the foetus and also certain organs such as the brain. Children born with a genetic disorder that restricts growth and reduces head/brain size are diagnosed with microcephalic primordial dwarfism (MPD).Whilst MPD is classed as a rare human disease, study of patients with this disease has revealed that a common underlying cause is inherited mutations in genes that encode proteins that function to replicate the genome. From this, it has been hypothesized that a reduction in the efficiency of DNA replication during embryonal development, prevents complete genome duplication being finished in time before the cell divides. This generates damage to the DNA, which triggers the cells with damaged DNA to die. As a result of increased cell death during embryogenesis, overall development of the foetus and several organ systems is restricted, which gives rise to a child with MPD. Therefore, the study of rare human diseases, such as MPD, has dramatically increased our knowledge about how fundamental processes such as DNA replication protect the cell from accumulating genetic damage and the consequences when this process fails. However, despite our progress, we still do not fully understand many important aspects of how these pathways function or indeed whether additional factors exist that are yet to be discovered. In this respect, we have identified a new protein, DONSON, which is mutated in patients with MPD that functions to help cells replicate their DNA and activate signals when DNA damage is detected. However, whilst it would appear that DONSON gene mutations are a relatively frequent cause of MPD, we still don't understand how DONSON regulates DNA replication, how DONSON signals the presence of DNA damage, how the cell instructs DONSON to carry out its function or why mutations in this gene cause MPD.Recently, we have identified a critical modification of the DONSON protein, termed arginine methylation. Our preliminary data indicates that arginine methylation of DONSON is vital for its ability to promote DNA replication but our understanding of why this is important is lacking. Therefore, the aim of this proposal is to study how arginine methylation of DONSON controls DNA replication and how defects in this process contribute to the development of disease. We hope by that increasing our knowledge of DONSON function and how it is regulated, our greater understanding of the disease will benefit patients with MPD through better disease management and an improved ability to genetically diagnose it.