Kheir Eyemen, Krude Torsten
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
J Cell Sci. 2017 Apr 1;130(7):1239-1250. doi: 10.1242/jcs.197566. Epub 2017 Feb 24.
Non-coding Y RNAs are essential for the initiation of chromosomal DNA replication in vertebrates, yet their association with chromatin during the cell cycle is not characterised. Here, we quantify human Y RNA levels in soluble and chromatin-associated intracellular fractions and investigate, topographically, their dynamic association with chromatin during the cell cycle. We find that, on average, about a million Y RNA molecules are present in the soluble fraction of a proliferating cell, and 5-10-fold less are in association with chromatin. These levels decrease substantially during quiescence. No significant differences are apparent between cancer and non-cancer cell lines. Y RNAs associate with euchromatin throughout the cell cycle. Their levels are 2-4-fold higher in S phase than in G1 phase or mitosis. Y RNAs are not detectable at active DNA replication foci, and re-associate with replicated euchromatin during mid and late S phase. The dynamics and sites of Y1 RNA association with chromatin are in concordance with those of the origin recognition complex (ORC). Our data therefore suggest a functional role of Y RNAs in a common pathway with ORC.
非编码Y RNA对脊椎动物染色体DNA复制的起始至关重要，但其在细胞周期中与染色质的关联尚未得到表征。在此，我们对可溶性和与染色质相关的细胞内组分中的人类Y RNA水平进行了定量，并从拓扑学角度研究了它们在细胞周期中与染色质的动态关联。我们发现，在增殖细胞的可溶性组分中平均约有100万个Y RNA分子，与染色质结合的则少5至10倍。在静止期，这些水平会大幅下降。癌细胞系和非癌细胞系之间没有明显差异。Y RNA在整个细胞周期中都与常染色质相关联。它们在S期的水平比G1期或有丝分裂期高2至4倍。在活跃的DNA复制位点检测不到Y RNA，它们在S期中期和后期与复制后的常染色质重新结合。Y1 RNA与染色质的动态变化和结合位点与起始识别复合物（ORC）一致。因此，我们的数据表明Y RNA在与ORC的共同途径中发挥功能作用。
