Snedeker Jonathan, Davis Brendon E M, Ranjan Rajesh, Wooten Matthew, Blundon Joshua, Chen Xin
Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD 21218, USA.
bioRxiv. 2024 Apr 29:2024.04.26.591383. doi: 10.1101/2024.04.26.591383.
Stem cells display asymmetric histone inheritance while non-stem progenitor cells exhibit symmetric patterns in the male germline lineage. Here, we report that components involved in lagging strand synthesis, such as DNA polymerase α and δ (Polα and Polδ), have significantly reduced levels in stem cells compared to progenitor cells. Compromising Polα genetically induces the replication-coupled histone incorporation pattern in progenitor cells to be indistinguishable from that in stem cells, which can be recapitulated using a Polα inhibitor in a concentration-dependent manner. Furthermore, stem cell-derived chromatin fibers display a higher degree of old histone recycling by the leading strand compared to progenitor cell-derived chromatin fibers. However, upon reducing Polα levels in progenitor cells, the chromatin fibers now display asymmetric old histone recycling just like GSC-derived fibers. The old new histone asymmetry is comparable between stem cells and progenitor cells at both S-phase and M-phase. Together, these results indicate that developmentally programmed expression of key DNA replication components is important to shape stem cell chromatin. Furthermore, manipulating one crucial DNA replication component can induce replication-coupled histone dynamics in non-stem cells in a manner similar to that in stem cells.
在雄性生殖系谱系中，干细胞表现出不对称的组蛋白遗传，而非干细胞祖细胞则呈现对称模式。在此，我们报告称，与后随链合成相关的组分，如DNA聚合酶α和δ（Polα和Polδ），与祖细胞相比，在干细胞中的水平显著降低。通过基因手段削弱Polα会使祖细胞中与复制偶联的组蛋白掺入模式变得与干细胞中的无法区分，这可以通过使用Polα抑制剂以浓度依赖的方式重现。此外，与祖细胞来源的染色质纤维相比，干细胞来源的染色质纤维在前导链上显示出更高程度的旧组蛋白循环利用。然而，当降低祖细胞中的Polα水平时，染色质纤维现在呈现出与生殖干细胞来源的纤维一样的不对称旧组蛋白循环利用。在S期和M期，干细胞和祖细胞之间新旧组蛋白的不对称性相当。总之，这些结果表明关键DNA复制组分的发育程序性表达对于塑造干细胞染色质很重要。此外，操纵一个关键的DNA复制组分可以在非干细胞中诱导出与干细胞中类似的复制偶联组蛋白动态变化。
