The role of the human transcription factor ZFP64 in centromeric transcription and maintenance of genomic stability

我们的身体由300亿个细胞组成。随着我们的身体生长，以及由于损伤、正常磨损和衰老而再生组织，这些细胞必须以快速的速度繁殖--我们的身体每分钟都有数百万个新细胞诞生！每次一个细胞复制它的内容，包括它的基因组副本，它都会经历一个称为细胞分裂的过程，这个过程将细胞内容物理上分成两半，成为未来的子细胞。在精确分离这两个新基因组的过程中出现的任何错误都可能导致戏剧性的、潜在的致癌基因突变，或者细胞死亡。因此，细胞分裂受到许多控制机制的仔细调控。基因组被排列成22对染色体，一旦复制，这些染色体就被内部细胞结构撕裂，形成新细胞的基因组。在这个过程中(有丝分裂)，染色体被细胞通过称为着丝粒的特殊结构捕获。大多数基因组都被蛋白质无情地阅读和‘转录’，这些蛋白质创造了一个短片段的RNA拷贝--通常是作为从我们DNA中编码的基因产生蛋白质的前驱。着丝粒被认为不包括在这个过程中，但最近几年令人惊讶地发现，着丝粒的转录对于准确的细胞分裂是必不可少的。这个至关重要的、进化上保守的过程一直很难研究，因为有两个主要障碍；第一，不知道哪些确切的DNA序列经历了转录。其次，在着丝粒上发挥这一作用的特定蛋白质(转录因子)尚不清楚。最近，我们实验室发现了一个名为ZFP64的转录因子，它是一个潜在的着丝粒转录因子。我们使用成像技术追踪这一因子在人类细胞中的位置，并兴奋地在着丝粒上看到它。重要的是，当我们专门从细胞中移除这种蛋白质时，我们看到着丝粒转录的数量减少了。我们还发现了着丝粒转录在每个细胞的整个生命周期中受到控制的可能机制--这是人类的另一个难以捉摸的现象。因此，我们现在准备利用最近的技术进步，这将提高我们发现着丝粒上哪些DNA序列被转录的能力，并询问其中哪些是由ZFP64控制的。我们的实验室是人类细胞成像和操作的专家，我们已经组装了一套有针对性的可行的实验，这将使我们能够最终测试ZFP64是否真的代表了第一个人类着丝粒转录因子。我们将与我们研究所和世界各地的专家合作者一起，进行标准实验和新出现的策略，以发现哪些DNA序列被转录。通过研究这种新的和重要的潜在着丝粒转录因子的详细机制，我们将朝着充分理解人类中的这一现象以及为什么它对准确的细胞分裂如此关键迈出了一大步。

Our bodies are comprised of 30 billion cells. As our body grows, and regenerates tissues due to injury, normal wear-and-tear and aging, these cells must multiply at rapid rates - with millions of new cells born every minute in our bodies! Each time a cell duplicates its content, including its copy of the genome, it undergoes a process termed cell division that physically separates the cell contents into two halves that become the future daughter cells. Any mistakes that occur in the precise separation of the two new genomes can lead to dramatic and potentially cancer-causing genetic mutations, or cell death. As a result, cell division is carefully regulated by many control mechanisms. The genome is arranged into 22 pairs of chromosomes that, once copied, are plucked apart by internal cell structures to form the genome of the new cells. During this process (mitosis), chromosomes are captured by the cell via specialised structures called centromeres. Most of the genome is relentlessly read and 'transcribed' by proteins that create an RNA copy of short sections - usually as a precursor to producing proteins from the genes encoded in our DNA. Centromeres were thought to be excluded from this process but over the last several years it was surprisingly discovered that transcription of centromeres is essential to accurate cell division.This crucially important and evolutionarily-conserved process has been difficult to study because of two major hurdles; First, it is not known which exact DNA sequences undergo transcription. Second, the specific proteins (transcription factors) that perform this role at the centromere are not known. Recently, our laboratory has identified a transcription factor named ZFP64 as a potential centromeric transcription factor. We used imaging to track the position of this factor within human cells, and excitingly see it at centromeres. Importantly, when we specifically remove this protein from cells we see a decrease in the amount of centromeric transcription. We have also discovered the possible mechanism by which centromeric transcription is controlled throughout the lifetime of each cell - another elusive phenomenon in humans. Therefore, we are now poised to take advantage of recent technological advances that will improve our ability to discover which DNA sequences at the centromere are transcribed, and to ask which of those are controlled by ZFP64. Our laboratory is expert in imaging and manipulating human cells and we have assembled a focussed and feasible set of experiments that will allow us to definitively test whether ZFP64 indeed represents the first human centromeric transcription factor. Together with expert collaborators within our research institute and worldwide, we will perform both standard experiments and also newly emerging strategies for discovering which DNA sequences are transcribed. By investigating the detailed mechanisms of this new and important potential centromeric transcription factor, we will make a large step towards full understanding of this phenomenon in humans, and exactly why it is so crucial for accurate cell division.