Dissecting the functional role of LINE1 retrotransposon-mediated interferon signaling in myeloid leukemia

项目总结 急性髓系白血病(AML)是成人最具侵袭性的血液系统恶性肿瘤之一，然而几十年来- 旧的化疗仍然是治疗的标准，由于其分子和 临床异质性。AML发展的一个新标志是LINE1的表观遗传学沉默 逆转座子，这是维持AML自我更新、分化阻断和基因组稳定所必需的。 LINE1反转录转座子的异常激活选择性损害人和小鼠急性髓系白血病细胞的增殖 不影响正常的造血；然而，LINE1活性如何抑制髓系仍然难以捉摸 白血病的发生。肿瘤靶向表观遗传抑制物如DNA的反转座子异常激活 去甲基化药物(DMA)在不同的疾病中产生I型干扰素(干扰素)介导的病毒模仿反应 癌症类型，包括白血病，导致细胞周期停滞和细胞凋亡。我们假设LINE1 反转录转座子通过调节I型干扰素信号参与髓系白血病的发展 由cGAS和/或RIG-I样受体(RLR)介导的LINE1基因产物的传感。这项提议将 建立LINE1介导的干扰素信号在髓系白血病发生中的功能作用 LINE1激活AML细胞中的天然免疫“病毒拟态”途径的机制。具体目标 这项建议的目的是：1)确定LINE1介导的干扰素信号在髓系中的功能作用 白血病的发生和进展；2)鉴定LINE1介导的干扰素激活的分子传感器 在AML中。内源性LINE1s在人AML细胞中的异位过表达和CRISPR激活 确定LINE1表达是否诱导I型IFN并影响细胞增殖、髓系分化、 和/或细胞凋亡。条件激活LINE1转基因小鼠与已建立的MLL-AF9的结合 逆转录病毒白血病模型将决定LINE1s激活是否诱导造血特异性I型干扰素 损害AML在体内的启动和/或维持。此外，cGAS、RIG-I或MDA5核的遗传消融 人急性髓系白血病细胞及其相应的基因敲除小鼠模型中单独或联合的酸传感器 将决定DNA和/或RNA传感通路的缺失如何影响LINE1诱导的炎症和AML 体内致病机制。总之，这些严格的基因研究将提供直接证据，证明 LINE1介导的干扰素信号在髓系白血病中的功能作用解决这些突出的知识 间隙对于了解反转录转座子-天然免疫串扰是否以及如何调制将是至关重要的 作为一种新的基于机制的治疗策略，选择性地根除AML细胞。

PROJECT SUMMARY Acute myeloid leukemia (AML) is one of the most aggressive hematologic malignancies in adults, yet decades- old chemotherapies remain the standard of care and few targeted therapies exist owing to its molecular and clinical heterogeneity. An emerging hallmark of AML development is the epigenetic silencing of LINE1 retrotransposons which is required to maintain AML self-renewal, differentiation blockade, and genomic stability. Aberrant reactivation of LINE1 retrotransposons selectively impairs propagation of human and mouse AML cells without affecting normal hematopoiesis; however, it remains elusive how LINE1 activity inhibits myeloid leukemogenesis. Aberrant retrotransposon reactivation by cancer-targeting epigenetic inhibitors such as DNA hypomethylating agents (DMA) produces a type I interferon (IFN)-mediated ‘viral mimicry’ response in various cancer types, including leukemias, resulting in cell cycle arrest and apoptosis. We hypothesize that LINE1 retrotransposons contribute to the development of myeloid leukemia by modulating type I interferon signaling mediated by cGAS and/or RIG-I-like Receptor (RLR) sensing of LINE1 gene products. This proposal will establish the functional role of LINE1-mediated IFN signaling in myeloid leukemogenesis and determine the mechanisms by which LINE1 activates innate immune ‘viral mimicry’ pathways in AML cells. The Specific Aims of this proposal intend to 1) establish the functional role of LINE1-mediated interferon signaling in myeloid leukemogenesis and progression; and 2) identify the molecular sensors of LINE1-mediated interferon activation in AML. Ectopic LINE1 overexpression and CRISPR activation of endogenous LINE1s in human AML cells will determine whether LINE1 expression induces type I IFNs and impacts cell proliferation, myeloid differentiation, and/or apoptosis. Combining a conditional LINE1 activation transgenic mouse with the established MLL-AF9 retroviral leukemia model will determine whether activation of LINE1s induces hematopoietic-specific type I IFN to impair AML initiation and/or maintenance in vivo. Moreover, genetic ablation of cGAS, RIG-I, or MDA5 nucleic acid sensors individually or in combination in human AML cells and their corresponding knockout mouse models will determine how loss of DNA- and/or RNA-sensing pathways affects LINE1-induced inflammation and AML pathogenesis in vivo. Altogether, these stringent genetic studies will provide direct evidence to establish the functional role of LINE1-mediated IFN signaling in myeloid leukemia. Addressing these outstanding knowledge gaps will be critical to inform whether and how modulation of the retrotransposon-innate immunity crosstalk may be leveraged as a new mechanism-based therapeutic strategy to selectively eradicate AML cells.