Institute for Cancer Genetics, Department of Pediatrics and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10019, USA.
Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA.
Sci Adv. 2024 Jun 7;10(23):eadn5175. doi: 10.1126/sciadv.adn5175. Epub 2024 Jun 5.
Inheritance of epigenetic information is critical for maintaining cell identity. The transfer of parental histone H3-H4 tetramers, the primary carrier of epigenetic modifications on histone proteins, represents a crucial yet poorly understood step in the inheritance of epigenetic information. Here, we show the lagging strand DNA polymerase, Pol δ, interacts directly with H3-H4 and that the interaction between Pol δ and the sliding clamp PCNA regulates parental histone transfer to lagging strands, most likely independent of their roles in DNA synthesis. When combined, mutations at Pol δ and Mcm2 that compromise parental histone transfer result in a greater reduction in nucleosome occupancy at nascent chromatin than mutations in either alone. Last, PCNA contributes to nucleosome positioning on nascent chromatin. On the basis of these results, we suggest that the PCNA-Pol δ complex couples lagging strand DNA synthesis to parental H3-H4 transfer, facilitating epigenetic inheritance.
表观遗传信息的遗传对于维持细胞身份至关重要。组蛋白 H3-H4 四聚体是组蛋白上表观遗传修饰的主要载体,它的转移代表了遗传表观遗传信息的一个关键但了解甚少的步骤。在这里,我们显示滞后链 DNA 聚合酶 Pol δ 与 H3-H4 直接相互作用,并且 Pol δ 和滑动夹子 PCNA 之间的相互作用调节亲本组蛋白向滞后链的转移,很可能独立于它们在 DNA 合成中的作用。当 Pol δ 和 Mcm2 的突变(这些突变会影响亲本组蛋白的转移)结合在一起时,与单独的突变相比,新生染色质上核小体的占有率降低得更多。最后,PCNA 有助于新生染色质上核小体的定位。基于这些结果,我们认为 PCNA-Pol δ 复合物将滞后链 DNA 合成与亲本 H3-H4 转移偶联起来,促进了表观遗传遗传。