Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030, Vienna, Austria.
Vienna Biocenter Core Facilities GmbH (VBCF), Dr. Bohr-Gasse 3, 1030, Vienna, Austria.
Chromosoma. 2021 Sep;130(2-3):215-234. doi: 10.1007/s00412-021-00762-z. Epub 2021 Jul 31.
The Drosophila Trithorax group (TrxG) protein ASH1 remains associated with mitotic chromatin through mechanisms that are poorly understood. ASH1 dimethylates histone H3 at lysine 36 via its SET domain. Here, we identify domains of the TrxG protein ASH1 that are required for mitotic chromatin attachment in living Drosophila. Quantitative live imaging demonstrates that ASH1 requires AT hooks and the BAH domain but not the SET domain for full chromatin binding in metaphase, and that none of these domains are essential for interphase binding. Genetic experiments show that disruptions of the AT hooks and the BAH domain together, but not deletion of the SET domain alone, are lethal. Transcriptional profiling demonstrates that intact ASH1 AT hooks and the BAH domain are required to maintain expression levels of a specific set of genes, including several involved in cell identity and survival. This study identifies in vivo roles for specific ASH1 domains in mitotic binding, gene regulation, and survival that are distinct from its functions as a histone methyltransferase.
果蝇 Trithorax 组（TrxG）蛋白 ASH1 通过机制与有丝分裂染色质保持关联，但其机制尚不清楚。ASH1 通过其 SET 结构域将组蛋白 H3 的赖氨酸 36 二甲基化。在这里，我们确定了果蝇中活细胞中 ASH1 用于有丝分裂染色质附着的必需 TrxG 蛋白结构域。定量活细胞成像表明，ASH1 在中期完全结合染色质需要 AT 钩和 BAH 结构域，但不需要 SET 结构域，而这些结构域在有丝分裂结合中都不是必需的。遗传实验表明，AT 钩和 BAH 结构域的破坏一起，但不是 SET 结构域的单独缺失，是致命的。转录谱分析表明，完整的 ASH1 AT 钩和 BAH 结构域是维持一组特定基因表达水平所必需的，包括几个与细胞身份和存活有关的基因。这项研究确定了 ASH1 结构域在有丝分裂结合、基因调控和存活中的特定作用，这些作用与其作为组蛋白甲基转移酶的功能不同。
