Ancestral functions of genes regulated by imprinting in mammals

基因组印记是胎盘哺乳动物和被子植物中一组基因的表观遗传调控形式。卵或精子内一个基因拷贝的甲基化导致一个亲本等位基因沉默，并导致来自母本或父本等位基因的单等位基因表达。这一过程已在哺乳动物，特别是小鼠中进行了广泛的研究，但对基因组印记的进化以及这些基因在受印记机制调控的物种之外的作用知之甚少，这可能反映了这些基因的祖先功能（在哺乳动物和印记出现之前）。自35年前首次发现以来，基因组印记的进化一直存在争议。迄今为止最有力的理论表明，基因组印记进化作用于已经在发育中调节生长的基因，称为父母冲突假说。迄今为止，在150多个印迹基因中，只有IGF 2和IGF 2 R被证实在印迹和非印迹物种的生长调节和发育方面具有保守的作用。该项目将以斑马鱼为模型，研究哺乳动物中的印记基因GRB 10，以研究其是否在非印记物种斑马鱼的发育中具有生长调节作用。这将检验目前关于基因组印记进化的假设。其他的作用，已与印记基因一起生长调节将被考虑。对于GRB 10，这可能是与发育中的胰岛素信号传导有关的作用。除此之外，目前可用的文献将被搜索，以调查什么是已知的其他印记基因在不同的物种。这可能会发现其他候选基因是保守的斑马鱼潜在的功能测试。方法可能包括但不限于：- 突变斑马鱼grb 10a/grb 10 b系将用于研究这些基因在发育中的作用，以及将产生CRISPR KO斑马鱼系以帮助确定基因功能和基因调控元件-使用显微镜进行表型评估-测量和比较身体参数-使用谱系特异性标记进行原位杂交-生物信息学方法，包括序列比对和在线工具，包括各种公开可用的数据库，以评估和收集有关其他印迹的已知信息。印迹物种与非印迹物种中的基因探索由印迹调控的基因的进化起源将有助于阐明基因组印迹进化的原因，以及这组基因是否参与调控发育，或者它们在健康和疾病中是否有更广泛或不同的目的。印记障碍导致严重的发育障碍，以及与其他问题，包括一些癌症和糖尿病的联系。这项研究将有助于提高我们对基因组印记的理解，并帮助我们理解为什么这会出错，并可能帮助我们学习如何在未来预防或治疗这些问题。总的来说，这将提高我们对人类健康和疾病这一领域的理解。

Genomic imprinting is a form of epigenetic regulation that governs a group of genes in placental mammals and angiosperms. Methylation of one gene copy within the egg or sperm causes silencing of one parental allele and results in monoallelic expression from either the maternal or paternal allele. This process has been extensively studied in mammals, especially mice, but little is known about the evolution of genomic imprinting and the role of these genes outside of species that are regulated by imprinting mechanisms, which likely reflects the ancestral functions of these genes (before mammals and imprinting arose). The evolution of genomic imprinting has been debated since it was first discovered around 35 years ago. The strongest theory to date suggests that genomic imprinting evolved to act on genes that already have established roles in regulating growth in development, known as the parental conflict hypothesis. To date, only IGF2 and IGF2R have been confirmed to have conserved roles regarding growth regulation and development across imprinted and non-imprinted species, out of over 150 imprinted genes. This project will use zebrafish as a model to look at the conserved gene GRB10, an imprinted gene in mammals, to investigate if this has a growth regulatory role in developing zebrafish, a non-imprinted species. This will look to test the current hypothesis for the evolution of genomic imprinting. Other roles that have been associated with imprinted genes alongside growth regulation will be considered. For GRB10, this could be a role relating to insulin signalling in development. Alongside this, currently available literature will be searched to investigate what is known about other imprinted genes in various species. This may identify other candidate genes that are conserved in zebrafish for potential functional testing.Methods may include but are not limited to:- Mutant zebrafish grb10a/grb10b lines will be used to investigate the role that these genes have in development as well as CRISPR KO zebrafish lines which will be generated to help determine gene function and characterise regulatory elements - Phenotypic evaluation using microscopy - Measurement and comparison of body parameters- In situ hybridisation using lineage specific markers- Bioinformatic methods including sequence alignments and online tools including a variety of publicly available databases to evaluate and gather information about what is known about other imprinted genes in imprinted species vs. non-imprinted species Exploring the evolutionary origins of genes that are regulated by imprinting will help to clarify why genomic imprinting evolved and whether this group of genes are involved in regulating development or if they have a broader or different purpose in health and disease. Imprinting disorders result in severe developmental disorders as well as having links to other issues including some cancers and diabetes. This research will help improve our understanding of genomic imprinting and will help us understand why this can go wrong and potentially help us learn how to prevent or treat these problems in the future. Overall, this will improve our understanding of this area of human health and disease.