Transcriptional and cell cycle control of erythropoiesis by E2F4

我们体内细胞数量的平衡是一个精心调节的过程，一旦受到干扰，就会导致许多危及生命的疾病，如癌症。通过对小鼠的遗传研究，我们之前确定了E2F4是一种蛋白质，它是体内红细胞正确数量所必需的。缺乏E2F4会导致小鼠胚胎贫血。我们把这些老鼠作为模型来研究如何控制体内的细胞生成。在最近的研究中，我们已经确定了增殖缺陷，特别是细胞分裂周期缺陷是胚胎中红细胞产生减少的主要原因。此外，我们利用基因微阵列技术，通过比较正常和缺乏E2F4小鼠的基因表达谱，来调查哪些基因在缺乏E2F4时发生了变化。这些研究已经确定了大量可能是E2F4分子靶点的基因，这些基因的表达缺陷可能最终导致这些小鼠的贫血。重要的是，我们的数据表明E2F4在控制细胞分裂所需基因的开关方面具有全新的功能。在这个提议中，我们描述了表征E2F4如何控制细胞分裂周期的方法，以确定它可能控制的确切过程，如DNA复制或染色体分离到子细胞。我们还将测试我们的假设，即E2F4在有核红细胞中能够开启基因的新作用。最后，我们描述了基因微阵列实验和一种新的启动子微阵列方法，以接近E2F4控制红细胞生成直接所需的分子。由于视网膜母细胞瘤中E2F蛋白家族或调节它们的蛋白的缺陷，pRB家族，已被认为是癌症发展的中心，这些研究将对癌症中该途径的治疗靶向具有广泛的意义。

The balance in the number of cells in our body is a carefully regulated process which, when disturbed, can lead to a number of life-threatening diseases such as cancer. Through genetic studies in the mouse, we previously identified E2F4 as a protein that is required for the correct number of red blood cells in the body. Lack of E2F4 results in anaemia in the mouse embryo. We have studied these mice as a model to understand how cell production in the body can be controlled. In recent studies, we have identified proliferation defects and in particular cell division cycle defects as the major cause for the decreased production of red blood cells in the embryo. In addition, we have utilised gene microarray technology to survey which genes change in the absence of E2F4 by comparing gene expression profiles in normal and E2F4 deficient mice. These studies have identified a large number of genes that could be molecular targets for E2F4 and whose defective expression could be ultimately responsible for the anaemia of these mice. Importantly, our data suggests a completely novel function for E2F4 in controlling the switching on of genes required for cell division. In this proposal, we describe approaches to characterise how E2F4 controls the cell division cycle to identify the exact process(es) it may control such as DNA replication or separation of chromosomes into daughter cells. We will also test our hypothesis for a novel role for E2F4 in being able to switch on genes in nucleated red blood cell. Finally, we describe gene microarray experiments and a new promoter microarray approach to close in on the molecules directly required for the E2F4 control of red blood cell production. Because defects in the E2F family of proteins or the proteins that regulate them, the retinoblastoma, pRB family, have been implicated as central for cancer development, these studies will have broad implications for therapeutic targeting of this pathway in cancer.