O'Haren Tommy, Aoki Tsutomu, Rieder Leila E
Department of Biology, Emory University, Atlanta, GA 30322.
Department of Molecular Biology, Princeton University, Princeton, NJ 08540.
Mol Biol Cell. 2025 Feb 1;36(2):br3. doi: 10.1091/mbc.E24-01-0028. Epub 2024 Dec 11.
To ensure that the embryo can package exponentially increasing amounts of DNA, replication-dependent histones are some of the earliest transcribed genes from the zygotic genome. However, how the histone genes are identified is not known. The pioneer factor CLAMP regulates the embryonic histone genes and helps establish the histone locus body, a suite of factors that controls histone mRNA biosynthesis, but CLAMP is not unique to the histone genes. Zelda collaborates with CLAMP across the genome to regulate zygotic genome activation and target early activated genes. We hypothesized that Zelda helps identify histone genes for early embryonic expression. We found that Zelda targets the histone gene locus early during embryogenesis, prior to histone gene expression. However, depletion of in the early embryo does not affect histone mRNA levels or prevent the recruitment of other factors. These results suggest the earliest events responsible for specifying the zygotic histone genes remain undiscovered.
为确保胚胎能够包装数量呈指数级增长的DNA，依赖复制的组蛋白是合子基因组中最早转录的一些基因。然而，组蛋白基因是如何被识别的尚不清楚。先驱因子CLAMP调节胚胎组蛋白基因，并有助于建立组蛋白基因座体，这是一组控制组蛋白mRNA生物合成的因子，但CLAMP并非组蛋白基因所特有。Zelda在全基因组范围内与CLAMP协作，以调节合子基因组激活并靶向早期激活的基因。我们假设Zelda有助于识别用于早期胚胎表达的组蛋白基因。我们发现，在胚胎发生早期，在组蛋白基因表达之前，Zelda就靶向组蛋白基因座。然而，早期胚胎中Zelda的缺失并不影响组蛋白mRNA水平，也不会阻止其他因子的募集。这些结果表明，负责指定合子组蛋白基因的最早事件仍未被发现。
