The regulation of transcriptional bursting by superenhancers

人体是由数万亿个细胞组成的。每个单细胞都在其DNA中包含了编码新个体的信息。密码以基因的形式出现，这些基因包含制造特定蛋白质的信息，以及在不同组织和发育的不同时间开启和关闭基因的调控元件(称为增强子)。很难想象一个人能在一根头发(60-70微米)上排列5到6个细胞。17世纪第一台显微镜的发展使科学家第一次看到了这种微小的结构。在接下来的300年里，显微镜已经被开发出来，这样我们现在就可以看到延伸到细胞直径千分之一(60-70纳米)的亚域。所谓的“超分辨率”显微镜现在使我们能够可视化增强剂和基因是如何相互作用来读取遗传密码的，在过去的十年里，通过制作实时电影来可视化正在读取的代码已经成为可能。这种以如此高的分辨率理解生物学的新方法，被称为纳米尺度，目前在生物学研究中是可能的，因此建立非常好的理解系统一直是至关重要的，使我们能够通过比较新的结果和以前对模型位置的分析来验证这些纳米尺度的发现。在我们的实验室里，我们研究了一种编码α-珠蛋白的基因的表达，这种基因有助于合成红细胞色素(血红蛋白)。这个基因是如何开启和关闭的，可能比几乎任何其他基因都更容易理解。我们已经证明了阿尔法基因是由五个增强子控制的，这些增强子作为一个整合的单位，当它启动它时，它与它的目标基因在物理上接近。通过用荧光探针标记基因产生的RNA，我们最近通过实时成像显示，当被激活时，基因不是持续活跃的，而是随着时间的推移而起伏不定。这是基因表达调控的关键机制。在目前的提案中，我们正在研究这一机制，特别是询问它是否受到增强子的调控。我们将通过比较没有增强子的基因表达模式，以及如何通过以不同的信息组合重新引入五种增强子来改变这一点来实现这一点。最后，我们将在他们的临床背景下测试我们的发现，检查人类增强剂的自然突变如何与受影响个体的红细胞变化相关。通过对基因调控的全面了解，我们的目标是找出基因通常是如何开启和关闭的，这在人类遗传病中是如何被干扰的，以及我们未来可能如何使用基因编辑工具来修改和治愈这些疾病。

The human body is made up of trillions of cells. Each single cell contains the information in its DNA to encode a new individual. The code comes in the form of genes that contain the information to make specific proteins, and regulatory elements (called enhancers) that switch the genes on and off in different tissues, and at different times in development. It is hard to imagine that one could line up 5 or 6 cells across a human hair (60-70 microns). Development of the first microscopes in the 17th century enabled scientists to see such minute structures for the first time. Over the next 300 years, microscopes have been developed so that we can now visualise subdomains that stretch across just one thousandth of the diameter of the cell (60-70 nanometers). So called "super-resolution" microscopes are now enabling us to visualise how enhancers and genes interact to read the genetic code and over the past decade it has been possible to visualise the code being read by creating real-time movies. This new approach to understanding biology at such high resolution, referred to as the nanoscale, is at the limits of what is currently possible in studying biology and so it has been critical to establish very well understood systems that enable us to verify these nanoscale findings by comparing new results with previous analyses of the model locus. In our laboratory we study expression of a gene encoding alpha-globin which contributes to the synthesis of the red cell pigment (haemoglobin). How this gene is switched on and off is probably better understood that almost any other gene. We have shown that the alpha gene is controlled by five enhancers which act as an integrated unit which comes into physical proximity with its target gene as it switches it on. By labelling the RNA produced by gene with a fluorescent probe we have recently shown by live imaging, that when activated, the gene is not continuously active but pulses on and off over time. This is a key mechanism underlying the regulation of gene expression. In the current proposal, we are investigating this mechanism and in particular asking if it is regulated by the enhancer. We will do this by comparing the pattern of gene expression with no enhancers and then how this is modified by re-introducing the five enhancers in various informative combinations. Finally, we will test our findings in their clinical context by examining how natural mutations of the human enhancers are correlated with changes in the red cells of affected individuals. By obtaining a complete understanding of gene regulation, we aim to find out how genes are normally switched on and off, how this is perturbed in human genetic disease and how we might use gene editing tools in future to modify and cure such diseases.