Transcriptional Regulation in ZFTA-RELA Ependymoma

摘要 癌症中的转录网络是来自发育和细胞识别程序的输入的集合， 致癌蛋白质、代谢回路和微环境相互作用。这些加在一起，最终将驾驶 肿瘤发生、维持和发展的不同阶段。室管膜瘤是一种侵袭性的肿瘤。 由单一基因事件驱动的儿童脑癌，ZFTA和RELA之间的基因融合。ZFTA-Rela (记为ZRFUS)是转化的有力驱动因素，其表达足以诱导EPN 在发育中的小鼠大脑中表达。尽管有证据表明ZRFUS作为一种异常转录 作为调节器，它用来驱动肿瘤形成的下游机制仍然没有明确的定义。这一知识 GAP阻碍了临床上易处理的EPN方法的确定，这些方法在 30多年了。因此，本提案的首要目标是剖析ZRFUS如何影响和 与驱动EPN肿瘤发生的不同转录程序相交。剖析ZRFUS是如何 推动EPN的发生，我们建立了第一个ZRFUS EPN宫内使用的自体小鼠模型 发育中的小鼠脑的电穿孔(IUE)。利用这个模型，我们证明了转录因子 ZRFUS EPN的启动需要发育中胶质形成所必需的转录因子，如SOX9 发展。在我们的模型中对这些发育中的TF进行条形码筛选，发现ETV5是领先的候选 这对ZRFUS的进展既是必要的，也是充分的。EPN中ETV5功能的进一步研究 揭示了它通过促进抑制染色质状态来抑制基因表达。在关键目标中 受ETV5抑制的基因是神经肽Y(NPY)，一种强大的神经递质，我们发现它具有 抑制ZRFUS进展并将瘤周边缘神经元突触重塑为减少 活动。基于这些令人信服的初步研究，我们假设发育编码的TF 控制肿瘤的启动和控制染色质的可及性，以调节肿瘤与神经元的相互作用 在大脑微环境中驱动EPN的生长。这一假设将在以下目标中得到检验：1) 确定SOX9如何通过修改染色质可及性影响ZRFUS EPN启动，2)破译 ETV5在ZRFUS EPN进展中的作用；3)确定NPY在室管膜瘤神经元重塑中的作用 微环境。

SUMMARY Transcriptional networks in cancer are a collection of inputs from developmental and cell identity programs, oncogenic proteins, metabolic circuits, and micro-environmental interactions. Together, these culminate to drive disparate stages of tumor initiation, maintenance, and progression. Ependymoma (EPN) is an aggressive form of pediatric brain cancer driven by a single genetic event, a gene fusion between ZFTA and RELA. ZFTA-RELA (denoted ZRFUS) is a potent driver of transformation, and its expression is sufficient to induce EPN when expressed in the developing mouse brain. Despite evidence that ZRFUS functions as an aberrant transcriptional regulator, the downstream mechanisms it utilizes to drive tumorigenesis remain poorly defined. This knowledge gap has hindered the identification of clinically tractable approaches for EPN, which have remained stagnant for over 30 years. Therefore the overarching goal of this proposal is to dissect how ZRFUS impacts and intersects with the diverse transcriptional programs that drive EPN tumorigenesis. To dissect how ZRFUS drives EPN tumorigenesis, we established the first autochthonous mouse model of ZRFUS EPN using in utero electroporation (IUE) of the developing mouse brain. Using this model, we demonstrated that transcription factor (TFs) essential for developmental gliogenesis, such as SOX9, are required for the initiation of ZRFUS EPN development. Barcode screening of these developmental TFs in our model identified ETV5 as a lead candidate that is both necessary and sufficient for ZRFUS progression. Further examination of ETV5 function in EPN revealed that it suppresses gene expression by promoting repressive chromatin states. Among the key target genes repressed by ETV5 is Neuropeptide Y (NPY), a potent neurotransmitter, which we found functions to suppress ZRFUS progression and remodel neuronal synapses in the peritumoral margins towards decreased activity. Based on these compelling preliminary studies, we hypothesize that developmentally encoded TFs govern tumor initiation and manipulate chromatin accessibility that regulate tumor-neuron interactions in the brain microenvironment to drive EPN growth. This hypothesis will be tested in the following aims: 1) Determine how SOX9 impacts ZRFUS EPN initiation through modifying chromatin accessibility, 2) Decipher the role of ETV5 in ZRFUS EPN progression, and 3) Define the role of NPY in remodeling the ependymoma neuronal microenvironment.