白血病AML1-ETO融合蛋白转录结合位点在基因组水平的分布规律

Genomic Distribution of AML1-ETO Fusion Protein Binding Sites

本研究探讨白血病t(8;21)染色体易位形成的融合癌蛋白AML1-ETO在2、9、19号3条染色体上基因组水平的结合位点分布,从而探索其在白血病发生发展过程中异常的转录调控模式,为靶向治疗药物研发以及临床治疗方案优化提供理论基础。应用染色质免疫沉淀技术与高通量的基因芯片相结合的ChIP-on-chip技术,使用覆盖上述3条染色体上所有基因组信息的瓦式基因芯片,在具有t(8;21)染色体易位的Kasumi细胞株上展开研究。实验分为抗ETO特异抗体组和随机打断基因组DNA对照组。通过MAT方法分析ETO抗体组相对于对照组的富集片段;应用CEAS分析工具分析富集片段在基因组上的分布特征,并进一步通过功能富集分析方法挖掘其中潜藏的生物学意义。结果表明:ETO抗体组在2、9、19号染色体上共得到富集片段588条,这些片段在基因组的定位分布特征如下:5.96%位于基因启动子区域,5.49%位于基因外显子区域,48.86%位于增强子区域,37.35%位于基因内含子区域,1.27%位于即时下游区域,0.87%位于3'UTR,0.2%位于5'UTR。进一步功能富集分析结果显示:参与代谢调节、细胞增殖、信号传导等功能的模块在AML1-ETO的潜在靶基因中富集。结论:AML1-ETO融合蛋白在基因组上的结合位点过半分布在经典转录因子结合区域(启动子、5'UTR和增强子),其余近半分布在非经典的区域,其下游调控的分子网络广泛涉及多种重要功能通路。

This study was purposed to characterize the genomic distribution of the binding sites for AML1-ETO fusion protein on chromosome 2, 9 and 19, and to further gain insights into the characteristics of transcriptional regulation by AML1-ETO in acute myeloid leukemia so as to provide theoretical basis for the development of targeted therapy and optimization for treatment. Chromatin immunoprecipitation （CHIP） coupled with high density tiling arrays （chip）, also known as ChIP-chip, was utilized in this study. ChIP-DNA enriched by an anti-ETO antibody and total genomic DNA of Kasumi cells were hybridized to tiling arrays, tiled through chromosome 2, 9 and 19. The ChIP enriched regions were identified using a model based analytical tool （MAT）. Genomic distribution of the ChIP regions was analyzed using publicly available CEAS web server. The Gene Ontology （GO） enrichment analysis was performed to excavate the biological significance. The results indicated that a total of 588 enriched regions were identified on chromosome 2, 9 and 19 by the anti-ETO antibody. A number of the identified regions were located within enhancers （48. 86% ） or introns （37.35%） , much smaller fractions were within proximal promoters （5.96%） or exons （5.49%）. Functional enrichment analysis showed that cell proliferation and signal transduction biological pathways were enriched in potential genes of AML-ETO. It is concluded that half of the AML1 -ETO binding sites are located within known transcriptional regulatory regions （promoter, 5 ＂UTR and enhancer）, while almost another half were within the sequences which were not previously reported as regulatory regions. The potential target molecular network of AML1-ETO is involved in several essential biological processes.