Assembly and epigenetic inheritance of the human centromere

说明书(申请人提供)：着丝粒是一种独特的染色质结构域，由含有着丝粒蛋白-A(CENP-A)的着丝粒特定核小体结合而成。着丝粒招募有丝分裂着丝粒，以确保有丝分裂过程中染色体的平等分离。着丝粒沿染色体的位置是由依赖于CENP-A核小体的表观遗传机制决定的。新的CENP-A核小体在G1早期的一段时间内组装到分裂细胞的着丝粒中。着丝粒的繁殖需要在DNA复制之前组装新的CENP-A核小体，以避免CENP-A核小体因其连续稀释而丢失。此前，我们确定Mis18复合体招募是表观遗传的决定性步骤。这项提案将探索通过招募Mis18复合体将新的CENP-A招募到着丝粒的机制。经典的组蛋白受到多种翻译后修饰(PTM)的影响，这些PTM驱动染色质相关因子的募集，并改变潜在染色质的功能。我们将探索两个新发现的CENP-A尾部的PTM的功能，氨基末端三甲基化和丝氨酸16和18的双重磷酸化。这里提出的实验将极大地促进我们对着丝粒遗传的表观遗传学机制的理解。此外，这项工作的影响将延伸到着丝粒以外，为乙酰化和甲基化或其他组蛋白变体编码的表观遗传信息的传播提供重要的洞察力。

DESCRIPTION (provided by applicant): The centromere is a unique chromatin domain defined by the incorporation of a centromere specific nucleosome containing centromere protein-A (CENP-A). The centromere recruits the mitotic kinetochore to ensure the equal segregation of chromosomes during mitosis. The location of the centromere along the chromosome is determined by an epigenetic mechanism that relies on the CENP-A nucleosome. New CENP-A nucleosomes are assembled into the centromeres of dividing cells during a discreet time in early G1. Propagation of the centromere requires assembly of new CENP-A nucleosomes prior to DNA replication to avoid the loss of CENP-A nucleosomes through their successive dilution. Previously we determined Mis18 complex recruitment is the defining step in epigenetic inheritance. This proposal will explore the mechanism by which new CENP-A is recruited to centromeres through the recruitment of the Mis18 complex. Canonical histones are subject to multiple posttranslational modifications (PTMs) that drive the recruitment of chromatin associated factors and modify the function of the underlying chromatin. We will explore the function of two newly identified PTMs of the CENP-A tail, amino-terminal trimethylation and dual phosphorylation of serine 16 and 18. The experiments proposed here will significantly advance our understanding of the epigenetic mechanism of centromere inheritance. Furthermore, the impact of this work will extend beyond the centromere to provide significant insight into the propagation of epigenetic information encoded by acetylation and methylation or other histone variants.