Unraveling the mechanism of DOT1A-mediated replication regulation in Trypanosoma brucei

翻译后组蛋白修饰调节许多重要的生物学过程，如复制，DNA修复和细胞周期控制。我们使用单细胞，真核寄生虫布氏锥虫作为一个模型系统，研究如何复制调控和发育分化控制的染色质为基础的机制。 我们特别感兴趣的是组蛋白H3甲基化的赖氨酸甲基转移酶的Dot1家族的成员的功能。Dot 1（端粒沉默的破坏物，也称为KMT 4）最初是在酵母中发现的，用于遗传筛选过度表达导致端粒沉默缺陷的基因。在上一个资助期，我们希望揭示T细胞中染色质结构在细胞周期调控和发育分化中的功能。布鲁塞。在这些项目的过程中，我们开始关注两个锥虫Dot1同源物DOT1A和DOT1B的功能，它们分别负责H3K76的二甲基化和三甲基化。令人惊讶的是，我们发现DOT1A介导的H3K76单甲基化或二甲基化调节复制起始。这是真核生物中复制的一种新的调节机制，在我们发表研究结果后不久，它也在人类细胞中被描述。基于这个成功的初始项目，我们现在的目标是解开这个细胞过程背后的机制事件。我们计划确定介导H3K76甲基化依赖性复制调控的分子机制，以了解更多关于这一基本生物学过程的信息。

Post-translational histone modifications regulate many important biological processes like replication, DNA repair and cell cycle control. We use the unicellular, eukaryotic parasite Trypanosoma brucei as a model system to study how replication regulation and developmental differentiation are controlled by chromatin-based mechanisms. We are specifically interested in the function of histone H3 methylation by a member of the Dot1 family of lysine methyltransferases. Dot1 (disruptor of telomeric silencing, also called KMT4) was initially discovered in yeast in a genetic screen for genes whose over-expression caused defects in telomeric silencing. In the previous funding period, we wanted to unravel the function of chromatin structure during cell cycle regulation and developmental differentiation in T. brucei. In the course of these projects, we began to focus on the function of two trypanosome Dot1 homologues DOT1A and DOT1B, which are responsible for di-methylation and tri-methylation of H3K76, respectively. Surprisingly, we discovered that DOT1A-mediated H3K76 mono- or di-methylation regulates replication initiation. This is a novel regulatory mechanism for replication in eukaryotes, which was also described in human cells shortly after we published our results. Based on this successful initial project, we now aim to unravel the mechanistic events behind this cellular process. We plan to identify the molecular machinery, which mediates H3K76 methylation-dependent regulation of replication to learn more about this basic biological process.