Role of HOTTIP/beta-catenin-HOXA9/PRMT1 axis in hematopoietic and leukemic stem cells

摘要： 自我更新是干细胞再生和维持细胞内环境稳定不可或缺的特性。 功能多样的细胞群体。造血干细胞(HSC)自我更新的调控直接联系 包括骨髓衰竭和各种血液疾病在内的一些造血退行性疾病， 然而，它的异常激活是白血病干细胞(LSCs)的一个决定性和不可或缺的特征 恶性表型。我们和其他人已经证明了急性髓系白血病(AML)的自我更新干细胞 细胞严重依赖于典型的Wnt信号通路的关键成分β-连环蛋白和同源框蛋白， HOXA9对于成年的HSCs来说基本上是可有可无的。尽管这些发现揭示了一个截然不同的功能 AML的需求和潜在的治疗机会，开发抗AML的小分子抑制剂 致癌转录因子到目前为止只取得了很小的成功，这主要是由于我们缺乏了解 关于这些蛋白质在介导造血自我更新中的分子调控，已经有了显著的意义 阻碍了制定有效的治疗战略来治疗由此产生的疾病的进展。有趣的是，我们 最近发现了典型的Wnt途径和包括HOXA9在内的后部HoxA基因座的共同调节 由长的非编码RNA(LncRNA)、HotTip。值得注意的是，我们还报道了β-连锁素之间的一种新的串扰 和HOXA9，它们可以超越它们在小鼠和人类HSC起源的AML中的个体需求。在……里面 寻找β-连环蛋白和HOXA9功能的关键介质，我们进一步鉴定了精氨酸蛋白 甲基转移酶1(PRMT1)也与DNA损伤和修复(DDR)有关，它可以在功能上取代 急性髓系白血病干细胞中的HOXA9或β-catenin来源于造血干细胞。PRMT1和DDR复合体是不偏不倚的 与CTCF/粘附素复合体、造血转录因子和核小体一起分离 CHIRP-MS在AML细胞中作为热尖端相互作用伙伴的重塑因子。这些发现不仅发现了 一个新的HotTip/β-catenin-HOXA9/PrMT1轴对介导造血自我更新至关重要，但也是铅 中心假设HotTip/β-catenin-HOXA9/PRMT1轴协调造血自我更新和 单个组件的功能和它们沿轴线的串扰的表征调节 造血特异性转录网络和DDR通路调控小鼠造血自我更新 疾病背景。在这个方案中，我们将1破译热尖和造血因子在体内的协同作用 对HOXA9和β-连环蛋白轴的调控；2)剖析β-连环蛋白的分子功能和调节。 HOXA9/Prmt1轴在正常和恶性造血中的作用成功完成建议的研究报告 不仅将建立分子原理，而且还将促进特定疗法的设计在调节 正常和恶性干细胞中的自我更新活性，这可能被转化为患者 福利。

Abstract: Self-renewal is an indispensable property that allows stem cells to regenerate and maintain the homeostasis of functionally diverse cell populations. Dergulation of self-renewal in hematopoietic stem cell (HSC) directly links to a number of hematopoietic degenerative disorders including bone marrow failure and various blood diseases, whereas its aberrant activation is a defining and indispensable feature of leukemia stem cells (LSCs) that sustain the malignant phenotypes. We and others have shown that self-renewal of acute myeloid leukemia (AML) stem cells heavily rely on the key component of canonical Wnt signaling pathway, β-catenin and the homeobox protein, HOXA9 that are largely dispensable for adult HSCs. Although these findings reveal a contrasting functional requirement and a potential therapeutic opportunity for AML, development of small molecule inhibitors against oncogenic transcription factors has so far met with very little success largely due to our lack of understanding about the molecular regulations of these proteins in mediating hematopoietic self-renewal, which has significantly hindered progress in developing effective therapeutic strategies to treat the resultant diseases. Intriguingly, we have recently revealed coregulation of both canonical Wnt pathway and posterior HOXA loci including HOXA9 by the long non-coding RNA (lncRNA), HOTTIP. Strikingly, we also report a novel crosstalk between β-catenin and HOXA9 that can override their individual requirement in both mouse and human AML of HSC origins. In search for crucial mediators for β-catenin and Hoxa9 functions, we further identified that protein arginine methyltransferase 1 (PRMT1), which also implicates in DNA damage and repair (DDR), can functionally replace HOXA9 or β-catenin in AML stem cell originated from HSCs. PRMT1 together with DDR complex are unbiasedly isolated along with CTCF/cohesin complex, hematopoietic transcription factors (TFs) and nucleosome remodeling factors as HOTTIP interacting partners by ChIRP-MS in AML cells. These findings not only discover a novel HOTTIP/β-catenin-HOXA9/PRMT1 axis critical for mediating hematopoietic self-renewal, but also lead to central hypothesis that HOTTIP/β-catenin-HOXA9/PRMT1 axis coordinates hematopoietic self-renewal and characterization of the functions of individual components and their crosstalk along the axis regulates hematopoietic specific transcription networks and DDR pathways to modulate hematopoietic self-renewal in the disease setting. In this proposal, we will 1 decipher cooperative action of HOTTIP and hematopoietic TFs in regulating HOXA9 and β-catenin axis; 2) dissect the molecular functions and regulation of β-catenin- HOXA9/Prmt1 axis during normal and malignant hematopoiesis. Success completion of proposed studies not only will establish the molecular principles, but also facilitate the design of specific therapeutics in modulating self-renewal activities in normal and malignant stem cells, which can be potentially translated into patient benefits.