Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Campus de Luminy, Marseille, France.
PLoS One. 2011;6(9):e24176. doi: 10.1371/journal.pone.0024176. Epub 2011 Sep 20.
The PLZF/RARA fusion protein generated by the t(11;17)(q23;q21) translocation in acute promyelocytic leukaemia (APL) is believed to act as an oncogenic transcriptional regulator recruiting epigenetic factors to genes important for its transforming potential. However, molecular mechanisms associated with PLZF/RARA-dependent leukaemogenesis still remain unclear.We searched for specific PLZF/RARA target genes by ChIP-on-chip in the haematopoietic cell line U937 conditionally expressing PLZF/RARA. By comparing bound regions found in U937 cells expressing endogenous PLZF with PLZF/RARA-induced U937 cells, we isolated specific PLZF/RARA target gene promoters. We next analysed gene expression profiles of our identified target genes in PLZF/RARA APL patients and analysed DNA sequences and epigenetic modification at PLZF/RARA binding sites. We identify 413 specific PLZF/RARA target genes including a number encoding transcription factors involved in the regulation of haematopoiesis. Among these genes, 22 were significantly down regulated in primary PLZF/RARA APL cells. In addition, repressed PLZF/RARA target genes were associated with increased levels of H3K27me3 and decreased levels of H3K9K14ac. Finally, sequence analysis of PLZF/RARA bound sequences reveals the presence of both consensus and degenerated RAREs as well as enrichment for tissue-specific transcription factor motifs, highlighting the complexity of targeting fusion protein to chromatin. Our study suggests that PLZF/RARA directly targets genes important for haematopoietic development and supports the notion that PLZF/RARA acts mainly as an epigenetic regulator of its direct target genes.
急性早幼粒细胞白血病（APL）中 11；17（q23；q21）易位产生的 PLZF/RARA 融合蛋白被认为作为一种癌基因转录调节因子，募集表观遗传因子到对其转化潜能重要的基因上。然而，与 PLZF/RARA 依赖性白血病发生相关的分子机制仍不清楚。我们通过在条件性表达 PLZF/RARA 的造血细胞系 U937 中进行 ChIP-on-chip 搜索，寻找特定的 PLZF/RARA 靶基因。通过比较在表达内源性 PLZF 的 U937 细胞中发现的结合区域与诱导 PLZF/RARA 的 U937 细胞中发现的结合区域，我们分离出特定的 PLZF/RARA 靶基因启动子。接下来，我们分析了我们鉴定的靶基因在 PLZF/RARA APL 患者中的基因表达谱，并分析了 PLZF/RARA 结合位点的 DNA 序列和表观遗传修饰。我们鉴定了 413 个特定的 PLZF/RARA 靶基因，其中包括许多参与造血调控的转录因子编码基因。在这些基因中，22 个在原发性 PLZF/RARA APL 细胞中显著下调。此外，受抑制的 PLZF/RARA 靶基因与 H3K27me3 水平升高和 H3K9K14ac 水平降低有关。最后，PLZF/RARA 结合序列的序列分析揭示了存在共识和退化的 RARE 以及组织特异性转录因子基序的富集，突出了靶向融合蛋白到染色质的复杂性。我们的研究表明，PLZF/RARA 直接靶向对造血发育重要的基因，并支持 PLZF/RARA 主要作为其直接靶基因的表观遗传调节剂的观点。
