Max-Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany.
PLoS Genet. 2012;8(6):e1002736. doi: 10.1371/journal.pgen.1002736. Epub 2012 Jun 14.
MOF is the major histone H4 lysine 16-specific (H4K16) acetyltransferase in mammals and Drosophila. In flies, it is involved in the regulation of X-chromosomal and autosomal genes as part of the MSL and the NSL complexes, respectively. While the function of the MSL complex as a dosage compensation regulator is fairly well understood, the role of the NSL complex in gene regulation is still poorly characterized. Here we report a comprehensive ChIP-seq analysis of four NSL complex members (NSL1, NSL3, MBD-R2, and MCRS2) throughout the Drosophila melanogaster genome. Strikingly, the majority (85.5%) of NSL-bound genes are constitutively expressed across different cell types. We find that an increased abundance of the histone modifications H4K16ac, H3K4me2, H3K4me3, and H3K9ac in gene promoter regions is characteristic of NSL-targeted genes. Furthermore, we show that these genes have a well-defined nucleosome free region and broad transcription initiation patterns. Finally, by performing ChIP-seq analyses of RNA polymerase II (Pol II) in NSL1- and NSL3-depleted cells, we demonstrate that both NSL proteins are required for efficient recruitment of Pol II to NSL target gene promoters. The observed Pol II reduction coincides with compromised binding of TBP and TFIIB to target promoters, indicating that the NSL complex is required for optimal recruitment of the pre-initiation complex on target genes. Moreover, genes that undergo the most dramatic loss of Pol II upon NSL knockdowns tend to be enriched in DNA Replication-related Element (DRE). Taken together, our findings show that the MOF-containing NSL complex acts as a major regulator of housekeeping genes in flies by modulating initiation of Pol II transcription.
MOF 是哺乳动物和果蝇中主要的组蛋白 H4 赖氨酸 16 特异性（H4K16）乙酰转移酶。在果蝇中，它作为 MSL 和 NSL 复合物的一部分，分别参与 X 染色体和常染色体基因的调控。虽然 MSL 复合物作为一种剂量补偿调节剂的功能已经相当清楚，但 NSL 复合物在基因调控中的作用仍知之甚少。在这里，我们报道了对果蝇基因组中四个 NSL 复合物成员（NSL1、NSL3、MBD-R2 和 MCRS2）的全面 ChIP-seq 分析。引人注目的是，大多数（85.5%）NSL 结合基因在不同细胞类型中都是组成型表达的。我们发现，在 NSL 靶向基因的启动子区域，组蛋白修饰 H4K16ac、H3K4me2、H3K4me3 和 H3K9ac 的丰度增加是其特征。此外，我们还表明，这些基因具有明确的无核小体区域和广泛的转录起始模式。最后，通过在 NSL1 和 NSL3 缺失细胞中进行 RNA 聚合酶 II（Pol II）的 ChIP-seq 分析，我们证明这两种 NSL 蛋白都需要有效地将 Pol II 募集到 NSL 靶基因启动子上。观察到的 Pol II 减少与 TBP 和 TFIIB 与靶启动子结合能力受损同时发生，表明 NSL 复合物是将起始前复合物最佳募集到靶基因上所必需的。此外，在 NSL 敲低后经历 Pol II 最大损失的基因往往富含 DNA 复制相关元件（DRE）。总之，我们的研究结果表明，含有 MOF 的 NSL 复合物通过调节 Pol II 转录的起始，作为果蝇中管家基因的主要调节剂。
