Department of Biological Chemistry, University of California Los Angeles School of Medicine, Los Angeles, California, USA.
PLoS One. 2009 Dec 31;4(12):e8535. doi: 10.1371/journal.pone.0008535.
Polycomb (PcG) and trithorax (trxG) proteins play important roles in establishing lineage-specific genetic programs through induction of chromatin modifications that lead to gene silencing or activation. Previously, we described an association between the MLL/SET1 complexes and a highly restricted, gene-specific DNA-binding protein Ap2delta that is required for recruitment of the MLL/SET1 complex to target Hoxc8 specifically. Here, we reduced levels of Ap2delta and Ash2l in the neuroblastoma cell line, Neuro2A, and analyzed their gene expression profiles using whole-genome mouse cDNA microarrays. This analysis yielded 42 genes that are potentially co-regulated by Ap2delta and Ash2l, and we have identified evolutionarily conserved Ap2-binding sites in 20 of them. To determine whether some of these were direct targets of the Ap2delta-Ash2l complex, we analyzed several promoters for the presence of Ap2delta and Ash2l by chromatin immunoprecipitation (ChIP). Among the targets we screened, we identified Fgfr3 as a direct transcriptional target of the Ap2delta-Ash2l complex. Additionally, we found that Ap2delta is necessary for the recruitment of Ash2l-containing complexes to this promoter and that this recruitment leads to trimethylation of lysine 4 of histone H3 (H3K4me3). Thus, we have identified several candidate targets of complexes containing Ap2delta and Ash2l that can be used to further elucidate their roles during development and showed that Fgfr3 is a novel direct target of these complexes.
多梳 (PcG) 和三价 (trxG) 蛋白通过诱导导致基因沉默或激活的染色质修饰，在建立谱系特异性遗传程序方面发挥重要作用。此前，我们描述了 MLL/SET1 复合物与高度受限的、基因特异性 DNA 结合蛋白 Ap2delta 之间的关联，该蛋白对于将 MLL/SET1 复合物特异性招募到靶基因 Hoxc8 是必需的。在这里，我们降低了神经母细胞瘤细胞系 Neuro2A 中 Ap2delta 和 Ash2l 的水平，并使用全基因组小鼠 cDNA 微阵列分析了它们的基因表达谱。该分析产生了 42 个可能由 Ap2delta 和 Ash2l 共同调控的基因，我们已经在其中 20 个基因中鉴定出了进化保守的 Ap2 结合位点。为了确定其中一些是否是 Ap2delta-Ash2l 复合物的直接靶标，我们通过染色质免疫沉淀 (ChIP) 分析了几个启动子中 Ap2delta 和 Ash2l 的存在情况。在我们筛选的靶标中，我们鉴定了 Fgfr3 是 Ap2delta-Ash2l 复合物的直接转录靶标。此外，我们发现 Ap2delta 对于包含 Ash2l 的复合物招募到该启动子是必需的，并且这种招募导致组蛋白 H3 赖氨酸 4 的三甲基化 (H3K4me3)。因此，我们已经鉴定出了几个包含 Ap2delta 和 Ash2l 的复合物的候选靶标，可以用于进一步阐明它们在发育过程中的作用，并表明 Fgfr3 是这些复合物的一个新的直接靶标。
