Mechanisms of Leukemogenesis in AMKL

! 项目总结/摘要 需要对白血病发生机制进行基础分析，以开发优化的 治疗方法。N6-甲基腺苷（m6 A）是最丰富的RNA修饰，在细胞凋亡中起着关键作用。 RNA代谢、转录稳定性和翻译效率。m6 A写入器和擦除器的异常调节 有助于白血病的发生，尽管甲基转移酶机制如何改变的确切机制 在白血病中的作用还有待证实迄今为止，甲基转移酶编写者中的突变尚未被确定， 一个例外：在急性巨核细胞白血病（AMKL）的复发性t（1;22）易位中， RBM 15与MKL 1融合，MKL 1是血清反应因子的转录辅因子 （战略成果框架）。了解RBM 15-MKL 1（RM）融合蛋白导致白血病的机制将有助于 阐明m6 A RNA甲基化紊乱在白血病发生中的作用，特别是AMKL，但也包括AML， 癌症一般。我们假设，对于RM相关AMKL的发展，MKL 1结构域异常靶向 RBM 15对SRF结合位点的活性，并且RBM 15将m6 A写入复合物募集到相关的RNA， 改变m6 A mRNA甲基化和转化所需基因的表达和/或 对巨核细胞命运定型和成熟非常重要。我们提出集中的，无偏见的全基因组 研究以确定m6 A表位转录组和SRF转录网络如何在RBM 15中被吸收， MKL 1 AMKL。基因组方法共有的候选靶基因（m6 A RNA）的功能效应 免疫沉淀、染色质作图、RNA稳定性测定和翻译组作图）以及 RM介导的白血病发生中的关键结构域的相关性将通过生长、分化 在RM诱导的鼠AMKL以及原发性人AMKL患者中， 异种移植（PDX）。这些研究具有高度的临床相关性，因为它们解决了一种独特的致病机制， AMKL通过全面分析基本的生物学机制，并将揭示以前未被发现的 表位转录组的调控可能是AML和其他癌症中一种新的共同致癌机制。 所提出的方法是多方面的，使用细胞系以及基因工程动物模型， 和原代人和鼠白血病样品。这些研究将有助于我们了解 通过阐明白血病中m6 A RNA甲基化酶复合物的一种组分的直接作用来研究白血病的发生 阐明了m6 A mRNA修饰在AML中的更广泛作用。 !

! Project Summary/Abstract Fundamental analysis of the mechanisms of leukemogenesis is required in order to develop optimized treatment approaches. N6-methyladenosine (m6A), the most abundant RNA modification, plays key roles in RNA metabolism, transcript stability, and translation efficiency. Aberrant regulation of m6A writers and erasers contributes to leukemogenesis, though the exact mechanisms how the methyltransferase machinery is altered in leukemia remains to be shown. Mutations in methyltransferase writers have not been identified to date, with one exception: in the recurrent t(1;22) translocation in acute megakaryoblastic leukemia (AMKL) a component of the m6A writer machinery, RBM15, is fused with MKL1, a transcriptional cofactor of serum response factor (SRF). Understanding the mechanism by which the RBM15-MKL1 (RM) fusion protein causes leukemia will shed light on the role of disordered m6A RNA methylation in leukemogenesis, specifically AMKL but also AML and to cancer in general. We hypothesize that for RM-associated AMKL to develop, the MKL1 domain aberrantly targets RBM15 activity to sites of SRF binding and that RBM15 recruits the m6A writer complex to associated RNAs, altering m6A mRNA methylation and expression of genes that are required for transformation and/or are important for megakaryocyte fate commitment and maturation. We propose focused, unbiased genome-wide studies to determine how the m6A epitranscriptome and the SRF transcriptional networks are coopted in RBM15- MKL1 AMKL. The functional effects of candidate target genes common to the genomic approaches (m6A RNA immunoprecipitation, chromatin mapping, RNA stability assays, and mapping of the translatome) as well as the relevance of critical domains in RM-mediated leukemogenesis will be tested with assays of growth, differentiation and oncogene dependence in RM-induced murine AMKL as well as primary human AMKL patient derived xenotransplants (PDX). The studies are highly clinically relevant as they address a unique mechanism causative of AMKL via comprehensive analysis of fundamental biologic mechanisms, and will reveal previously unidentified regulation of the epitranscriptome that may be a novel shared oncogenic mechanism in AML and other cancers. The proposed approaches are multifaceted, using cell lines as well as genetically engineered animal models, and primary human and murine leukemia samples. The studies will contribute to our understanding of leukemogenesis by elucidating the direct role of a component of the m6A RNA methylase complex in leukemia shedding light on the broader role of m6A mRNA modifications in AML. !