Functional dissection of the genetic interaction network that affects growth of cells with telomere defects: implications for health and disease

遗传物质DNA包含了制造细胞和有机体的指令。出于这些原因，DNA的稳定性对于将遗传信息代代相传非常重要。在人类和许多更简单的生物如酵母中，DNA存在于含有超长、线性、双链DNA分子的染色体中，从某种意义上说，就像非常长的鞋带。就像鞋带一样，中间断裂或受损的染色体比末端受损的染色体用处小得多。即便如此，就像鞋带一样，正常情况下，每条染色体的末端都要适当地“封顶”，这一点通常很重要。鞋带两端的帽子被称为银链，而位于染色体末端的帽子上的帽子被称为端粒。如果端粒失效，那么端粒附近的遗传物质可能会受损或丢失，端粒未封顶的细胞可能不再被允许分裂。细胞对有缺陷的端粒的反应在很大程度上受到与基因组其他地方的DNA损伤相同的途径的调节。在人类中，这些机制在衰老和癌症中扮演着重要的角色。这个项目研究了特定的细胞内防御机制如何与其他机制相互作用来应对端粒缺陷。其中一些机制可以比作用于减速车辆的机制。当细胞内发生端粒损伤时，细胞也会减缓甚至停止细胞分裂。我们特别感兴趣的是衡量和理解不同机制之间的相互作用，并看看如果两个机制而不是单一机制有缺陷会发生什么。在汽车中，我们知道脚刹车、手刹和齿轮提供了不同的减速机制，所有的机制都是有用的。我们还知道，汽车中的机械装置之间存在一些冗余。也就是说，如果手刹失灵，那么脚刹车和齿轮就变得更重要了。进一步类比，我们有兴趣研究刹车机制是如何在细胞内相互作用的。酵母菌是研究这些基本问题的很好的实验系统。酵母已经被培养了几千年，用来制作面包、葡萄酒和啤酒，很容易在实验室里种植和研究。此外，酵母细胞的端粒结构与人类端粒相似，因此对酵母细胞进行了与人类健康和疾病相关的研究。我们将利用传统的酵母方法和更现代的机器人遗传方法来检测酵母细胞内的大量相互作用。在哺乳动物细胞中进行这样的实验是不可能的，也是过于昂贵的。我们预计，我们的许多发现也将与人类端粒功能相关，因为我们在酵母中研究的许多蛋白质和途径都是保守的。基于我们对酵母的研究，我们将检查人类的基因组，特别是那些活到85岁或更高的人的基因组，看看同样的途径是否可能在人类身上受到影响。如果是这样的话，这些人可能对端粒相关的人类疾病特别具有抵抗力或易感。

The genetic material DNA contains the instructions to make cells and organisms. For these reasons stability of DNA is important to pass on genetic information from one generation to the next. In humans and many simpler organisms such as yeast, DNA is found in chromosomes that contain extremely long, linear, double stranded DNA molecules, in a sense like very long shoelaces. Just as with shoelaces, a chromosome that is broken or damaged in the middle is much less useful than a chromosome that is damaged at the end. Even so, just as with shoelaces, it is normally important that the end of each chromosome is properly "capped". The caps at the ends of shoelaces are called aglets, and those at the caps at the ends of chromosomes are called telomeres. If telomeres fail, then genetic material near the telomeres can be damaged or lost and cells with uncapped telomeres may no longer be permitted to divide. Cellular responses to defective telomeres are largely regulated by the same pathways that respond to DNA damage elsewhere in the genome. In human beings these mechanisms play important roles in ageing and cancer.This project examines how specific intra-cellular defense mechanisms interact with other mechanisms to respond to telomere defects. Some of these mechanisms can be likened to the mechanisms used to slow down vehicles. When telomere damage occurs inside cells, the cells also slow or even stop cell division. We are particularly interested in measuring and understanding interactions between different mechanisms and seeing what happens if two mechanisms, rather than a single mechanism, are defective. In a car we know that the footbrake, the handbrake and gears provide different mechanisms to reduce speed and all the mechanisms are useful. We also know that there is some redundancy between mechanisms in a car. That is, if the hand brake fails then the foot brake and gears become more important. Taking this analogy further, we are interested in studying how brake mechanisms interact, inside cells. Yeast is a good experimental system to study these fundamental questions. Yeast has been cultured for thousands of years for making bread, wine and beer and is very easy to grow and study in the lab. Furthermore telomere structure in yeast cells is similar to that in human telomeres, making studies in yeast cells relevant to human health and disease. We will make use of traditional yeast methods and more modern robotic genetic methods to examine large numbers of interactions inside yeast cells. Such experiments are not possible or are too expensive to perform in mammalian cells. We expect that many of our discoveries will also be relevant to human telomere function since many of the proteins and pathways we study in yeast are conserved. Based on our studies in yeast we will examine genomes from human beings, particularly those who have lived to the age of 85 or more, to see if the same pathways are likely to be affected in human beings. If so, such persons might be particularly resistant or susceptible to telomere related human diseases.