The iBAC genomic DNA expression library

最近完成的获得所有人类基因的完整DNA序列的项目，被称为人类基因组，开辟了生物学的新时代。我们现在能够提出一系列的实验，这在以前是不可能的。我们基因的DNA序列证实，我们绝大多数的DNA序列不提供制造蛋白质的信息，但包含调控信息，以在发育的正确时间在正确的细胞中打开和关闭基因，或使蛋白质生产上下波动。这种DNA序列被称为非编码DNA，以前很难定义和研究。多年来，从染色体中取出一个基因序列，并用它在实验室培养的细胞中制造或“表达”一种蛋白质已经成为可能。然而，以前从染色体中取出一个基因及其所有调控元件并不容易。在细胞内，对基因表达的控制是复杂的，如果基因在没有自然调节元件的情况下使用，就很难控制它们何时产生蛋白质以及产生多少蛋白质。这个项目将收集所有的基因，包括它们的调控序列，这样它们就可以被传递到细胞中，在正确的调控下制造蛋白质。这在以前是不可能的，因为调控区域的基因序列比基因本身大得多，有时是基因本身的十倍，而且用大片段的DNA进行基因表达是困难的。科学家将基因传递给细胞的一种方法是使用病毒，病毒已经进化成强大的基因传递机器。然而，大多数病毒太小，无法携带包含调控元件时所需的大片段DNA。利用单纯疱疹病毒（一种大型DNA病毒）的病毒传递方法取得的新进展，现在使我们能够传递带有所有调控元件的基因。该病毒已被改造成基因传递载体，这意味着所有致病的病毒DNA都已被移除，只留下基因传递所需的最少部分。现在，病毒载体可以携带人类基因及其所有大型调控元件，并将它们有效地传递到实验室培养的细胞中。这一突破最初是由Wade-Martins博士在2001年取得的，目前他在牛津大学的实验室正在不断改进这一系统。在这个项目中，韦德-马丁斯博士与桑格研究所的科学家们合作，桑格研究所位于剑桥郊外的欣克斯顿，是世界上最大的基因研究中心之一。他们将一起收集所有小鼠基因，包括它们的调控元件，以一种可用于根据其功能寻找新基因的格式。这些测试可以在小鼠或人类细胞中进行，因为人类和小鼠的DNA序列非常相似。这些基因的集合被称为文库，它将包含老鼠体内大约3万个基因。这些藏品将提供给科学界，并将成为极有价值的新资源。我们将通过寻找与范可尼贫血有关的基因来测试这个文库，范可尼贫血是一种导致癌症和骨髓衰竭的严重疾病。以前寻找这种疾病的一些基因的尝试失败了，我们相信我们的新方法有很大的成功机会。我们还将利用该文库寻找与干细胞控制有关的基因。干细胞是一种可以变成任何细胞类型的细胞，了解它们是如何被基因调节成脑细胞、肌肉细胞或肝细胞的，是目前生物学的关键问题之一。总的来说，这是一个令人兴奋的新项目，将两个在英国处于世界领先地位的研究领域具有相似兴趣的实验室聚集在一起。

The recent completion of projects to obtain the complete DNA sequence of all human genes, known as the human genome, has opened up a new era of biology. We now are able to propose a whole series of experiments which would previously not have been possible. The DNA sequence of our genes confirmed that the vast majority of our DNA sequence does not provide information to make proteins, but contains regulatory information to turn genes on and off, or to turn protein production up and down, in the right cells at the right time in development. This DNA sequence, called non-coding DNA, has previously been difficult to define and hard to study. For many years it has been possible to take a gene sequence out of a chromosome and use it to make, or 'express', a protein in cultured cells grown in the laboratory. However, it has not been easy before to take a gene from a chromosome together with all of its regulatory elements. Inside cells the control of gene expression is complex and if genes are used without their natural regulatory elements it is difficult to control when they make protein and how much they make. This project will make a collection of all genes, including for the first time their regulatory sequences, in a way that they can be delivered to cells to make proteins under correct regulation. This has not been possible before because the genetic sequence of the regulatory regions is much larger than the gene itself, sometimes ten times as large, and working with large pieces of DNA for gene expression is difficult. One way scientists deliver genes to cells is using viruses, which have evolved as powerful gene-delivery machines. However, most viruses are too small to carry the large pieces of DNA required when the regulatory elements are included. New advances in viral delivery methods using herpes simplex virus, a large DNA virus, now allow us to deliver genes with all their regulatory elements. The virus has been engineered into a gene delivery vector, which means all the disease-causing viral DNA has been removed, leaving only the bare minimum required for gene delivery. Now, the viral vector can carry human genes with all their large regulatory elements and deliver them efficiently to cultured cells in the laboratory. This breakthrough was originally made by Dr Wade-Martins in 2001 and the system is being continuously improved in his laboratory at Oxford University. In this project Dr Wade-Martins is teaming up with scientists from the Sanger Institute, at Hinxton just outside Cambridge, one of the largest centres for genetic studies in the world. Together they will be making a complete collection of all mouse genes, including their regulatory elements, in a format which can be used to look for new genes based on their function. These tests can take place in either mouse or human cells because the DNA sequences of humans and mice are extremely similar. The collection of genes is called a library, and will contain all the approximately 30,000 genes present in a mouse. The collection will be made available to the scientific community and will be an extremely valuable new resource. We will test the library by looking for genes involved in a disease called Fanconi's anaemia, a severe disease which causes cancer and bone-marrow failure. Previous attempts to find some of the genes for this disease have failed, and we believe our new approach has a high chance of success. We will also use the library to look for gene involved in the control of stem cells. Stem cells are cells which can become any cell type, and understanding how they are regulated by genes to become, for example, a brain cell, muscle cell or liver cell is one of the key questions in biology at the moment. Overall, this is an exciting new project bringing together two laboratories with similar interests in a area of research in which the UK is a world leader.