Role of lincRNAs in HSC function and leukemogenesis

摘要 Hox基因，特别是HOXA和HOXB基因，对于维持自我更新和自我更新之间的平衡至关重要。 和造血干细胞（HSC）的分化。HOXA和/或HOXB基因的失调是一种 白血病转化的主要机制。异常HOX基因表达与融合相关 涉及MLL 1和NUP 98的基因，以及NPM 1和CEBPA的突变。然而，表观遗传机制 调控HOX基因转录以控制HSC功能的机制仍有待探索。此外，关键是 阐明HOX基因是如何在白血病发生过程中异常激活的。更好地了解这些 关键问题将有助于开发高效和有选择性的靶向治疗。我们最近 发现了一个与HoxB基因座相关的长基因间非编码RNA（lncRNA），HoxBlinc， 通过组织CTCF介导的活性染色质结构域进行造血谱系定型和分化 以促进前部HoxB基因激活。HoxBlinc募集Setd 1a/MLL 1复合物以激活HoxB 基因.我们发现HoxBlinc lncRNA在相当一部分AML患者中过表达， HoxBlinc高表达的患者与HoxBlinc低表达的患者相比， HOCBLINC表达式。此外，HoxBlinc在小鼠中的转基因表达导致增加的HoxBlinc库。 LT-HSC和ST-HSC，以及致死性AML样疾病的发展。我们假设HoxBlinc lncRNA是 通过控制Hox和其他关键HSC调节基因的激活， 通过调节染色质动力学。此外，HoxBlinc的上调可能代表了一种有效的治疗方法。 白血病发生中的致癌事件。为了验证这些假设，我们将：1）确定HoxBlinc的作用 通过进行系列移植和配对子细胞测定，lncRNA在HSC生物学和行为中的作用 使用纯化的HoxBlinc-Tg HSC; 2）确定转基因HoxBlinc表达是否足以干扰HoxBlinc-Tg HSC; 造血并导致小鼠骨髓恶性肿瘤; 3）研究HoxBlinc的机制 lncRNA通过检测HoxBlinc染色质的整体变化来调节不同阶段的HSC的行为 结合，3D染色质组织，组蛋白修饰，染色质可及性，以及转录 从WT和HoxBlinc-Tg小鼠纯化的HSC中的特征; 4）检查HoxBlinc-Tg小鼠是否发挥HoxBlinc-Tg小鼠的功能。 HSC中的lncRNA依赖于Setd 1a/MLL 1复合物; 5）探索HOXBLINC lncRNA是否可以 作为AML的有效治疗靶点，检查HoxBlinc丢失是否能够减轻 NPM 1C+或其他突变驱动的髓系恶性肿瘤，通过消除特征性异常HOX基因 表情拟议研究的成功将导致对监管的基本知识， 通过lncRNA的HSC。我们的研究可以建立HoxBlinc作为一个强大的致癌lncRNAs， 白血病发生HOXBLINC lncRNA可能是治疗高表达AML的新靶点。 HOXBLINC表达式。

Abstract Hox genes, especially HOXA and HOXB genes, are critical for maintaining the balance between self-renewal and differentiation of hematopoietic stem cells (HSCs). Dysregulation of HOXA and/or HOXB genes is a dominant mechanism of leukemic transformation. Aberrant HOX gene expression is associated with fusion genes involving MLL1 and NUP98, and mutations in NPM1 and CEBPA. However, the epigenetic mechanisms that regulate HOX gene transcription to control HSC function remain to be explored. Furthermore, it is critical to elucidate how HOX genes are aberrantly activated during leukemogenesis. Better understanding of these critical questions will assist in the development of highly effective and selective targeted therapies. We recently identified a HoxB locus associated long intergenic noncoding RNA (lncRNA), HoxBlinc, which controls hematopoietic lineage commitment and differentiation by organizing CTCF mediated active chromatin domain to facilitate anterior HoxB gene activation. HoxBlinc recruits the Setd1a/MLL1 complexes to activate HoxB genes. We found that HoxBlinc lncRNA is overexpressed in significant portions of AML patients, and AML patients with high HoxBlinc expression had significantly shortened survival compare to patients with low HOCBLINC expression. Furthermore, transgenic expression of HoxBlinc in mice leads to increased pools of LT-HSCs and ST-HSCs, and development of lethal AML-like disease. We hypothesize that HoxBlinc lncRNA is a critical epigenetic regulator of HSCs, by controlling the activation of Hox and other key HSC-regulating genes through modulation of chromatin dynamics. In addition, up-regulation of HoxBlinc may represent a potent oncogenic event in leukemogenesis. To test these hypothesis, we will: 1) determine the role of HoxBlinc lncRNA in HSC biology and behavior by performing serial transplantation and paired daughter cell assays using purified HoxBlinc-Tg HSCs; 2) determine whether transgenic HoxBlinc expression is sufficient to perturb hematopoiesis and cause myeloid malignancies in mice; 3) investigate the mechanism(s) by which HoxBlinc lncRNA regulates behaviors of different stages of HSCs by examining global changes in HoxBlinc chromatin binding, 3D chromatin organization, histone modifications, chromatin accessibility, as well as transcription profiles in HSCs purified from WT and HoxBlinc-Tg mice; 4) examine if the function exerted by HoxBlinc lncRNA in HSCs is dependent on the Setd1a/MLL1 complexes; 5) explore whether HOXBLINC lncRNA can serve as an effective therapeutic target for AMLs by examining whether HoxBlinc loss is capable of mitigating NPM1C+- or other mutation-driven myeloid malignancies via abrogating the signature aberrant HOX gene expression. Success of the proposed studies will result in fundamental knowledge regarding the regulation of HSCs by lncRNAs. Our studies could establish HoxBlinc as a powerful oncogenic lncRNAs during leukemogenesis. HOXBLINC lncRNA might represent a novel therapeutic target for AMLs with high HOXBLINC expression.