Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.
Institut de recherches clinique de Montréal (IRCM) and Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC H2W 1R7 Canada.
Cell Rep. 2017 Oct 31;21(5):1361-1374. doi: 10.1016/j.celrep.2017.10.033.
Nucleosomes are believed to carry epigenetic information through the cell cycle, including through DNA replication. It has been known for decades that parental histones are reassembled on newly replicated chromatin, but the mechanisms underlying histone inheritance and dispersal during DNA replication are not fully understood. We monitored the fate of histones H3 or H4 from a single nucleosome through DNA replication in two in vitro systems. In the SV40 system, histones assembled on a single nucleosome positioning sequence can be inherited by their own daughter DNA but are dispersed from their original location. In Xenopus laevis extracts, histones are dynamic, and nucleosomes are repositioned independent of and prior to DNA replication. Nevertheless, a high fraction of histones H3 and H4 that are inherited through DNA replication remains near its starting location. Thus, inheritance of histone proteins and their dispersal can be mechanistically uncoupled.
核小体被认为通过细胞周期携带表观遗传信息，包括通过 DNA 复制。几十年来，人们一直知道亲代组蛋白在新复制的染色质上重新组装，但 DNA 复制过程中组蛋白继承和分散的机制尚未完全了解。我们在两个体外系统中通过 DNA 复制监测单个核小体中组蛋白 H3 或 H4 的命运。在 SV40 系统中，组装在单个核小体定位序列上的组蛋白可以通过其自身的子 DNA 继承，但会从其原始位置分散。在非洲爪蟾提取物中，组蛋白是动态的，核小体在 DNA 复制之前独立于 DNA 复制而重新定位。然而，通过 DNA 复制继承的大量组蛋白 H3 和 H4 仍然靠近其起始位置。因此，组蛋白蛋白的继承和其分散可以在机制上解耦。
