Defining transcriptional networks and chromatin conformations regulating glioma tumorigenesis

恶性胶质瘤是最常见和最致命的原发脑肿瘤。尽管目前的治疗方法 大多数神经胶质瘤患者在确诊后一年内死亡。基因组不稳定性与异常 调节祖细胞群体中的细胞命运决定与胶质瘤有关，这导致了这样的观点 基因突变和发育背景的融合导致了肿瘤的发生。最新发现 证明在胶质瘤中有大量的发育转录因子被激活。这些研究 这表明，在胶质瘤形成过程中，控制胶质细胞形成的基因调控程序被重新利用， 指出了神经胶质发育和肿瘤发生的共同转录要求。因此，它是至关重要的 我们利用我们对神经胶质细胞发育的了解来获得对生物学和 治疗神经胶质瘤。我们之前已经确定了一个胶质生成转录复合体-Sox9/Brn2-即 对神经胶质形成的启动很重要。我们发现，在恶性胶质瘤小鼠模型中， 该复合体结合DNA调节元件的能力导致神经胶质细胞启动的表达减少 核因子-IA(NFIA)与降低肿瘤发生。我们的初步数据显示，一种蛋白质 MED12(介体复合体亚基12)，在胶质细胞发育过程中表达，与染色质相连 与肿瘤发生有关的构象与Sox9/Brn2复合体有关。此外， 皮质星形胶质细胞培养中MED12表达减少影响DNA染色质构象 Nfia轨迹。因此，我们建议探索胚胎胶质细胞发育和 通过描绘调控神经胶质瘤的转录回路和调控环境来研究肿瘤的发生 肿瘤发生学。对这些机制的分析有望识别出在 神经胶质瘤形成。 我们把这个建议的重点放在转录复合体的功能上，该复合体对神经胶质细胞的分化很重要， -Sox9/Brn2/MED12-及其通过基因调控元件在协调转录机制中的作用， 以及神经胶质瘤发生过程中的染色质构象。我们将研究MED12在胶质瘤形成中的作用 在一种新的小鼠恶性肿瘤模型中使用广泛的体外和体内技术的肿瘤细胞生物学 神经胶质瘤。我们将询问MED12在介导增强子/启动子中的作用机制 通过利用最新的技术进步在胶质瘤形成和进展过程中的相互作用 远距离染色质相互作用的检查(即3C分析)。我们将从功能上验证下游 可能影响胶质瘤形成的Sox9/Brn2/MED12复合体的靶基因。总而言之，这些研究将 定义发育相关的转录机制，包括基因调控元件和 染色质结构界面影响胶质瘤生物学并揭示潜在调控的新基因靶点 神经胶质瘤形成。

Malignant gliomas are the most common and deadly primary brain tumor. Despite current therapeutic approaches, most glioma patients die within one year of diagnosis. Genomic instability coupled with aberrant regulation of cell-fate decisions in progenitor cell populations has been linked to glioma, leading to the view that a convergence of genetic mutation and developmental context lead to tumorigenesis. Recent findings demonstrate that a large set of developmental transcription factors are activated in gliomas. These studies suggest that the gene regulatory programs governing glial cell formation are reutilized during glioma formation, pointing to common transcriptional requirements for glial development and tumorigenesis. Therefore, it is critical that we leverage our understanding of glial cell development to gain valuable insights into the biology and treatment of gliomas. We have previously identified a gliogenic transcriptional complex – Sox9/Brn2– that is important for the initiation of gliogenesis. We showed that in a mouse model of malignant glioma disruption of the ability of the complex to bind DNA regulatory elements leads to decreased expression of the glial initiating factor Nuclear Factor-IA (NFIA) and reduced tumorigenesis. Our preliminary data demonstrate that a protein Med12 (Mediator Complex subunit 12), which is expressed during glial cell development, linked to chromatin conformations, and implicated in cancer tumorigenesis, associates with the Sox9/Brn2 complex. Further, reduction of Med12 expression in cortical astrocyte cultures compromises DNA chromatin conformation at the Nfia locus. Therefore, we propose to explore the parallels between embryonic glial development and tumorigenesis by delineating the transcriptional circuitry and regulatory landscape governing glioma tumorigenesis. Analysis of these mechanisms is expected to identify molecular targets important in gliomagenesis. We focus this proposal on the function of a transcriptional complex, important for glial cell differentiation, -Sox9/Brn2/Med12- and its role in coordinating transcriptional mechanisms through gene regulatory elements, and chromatin conformations during gliomagenesis. We will investigate the role of Med12 in glioma formation and tumor cell biology using a wide range of in vitro and in vivo techniques in a novel mouse model of malignant glioma. We will interrogate the mechanisms by which Med12 functions in mediating enhancer/promoter interaction during glioma formation and progression by exploiting recent technological advances that allow for examination of long-range chromatin interactions (i.e. 3C Assays). We will functionally validate downstream target genes of the Sox9/Brn2/Med12 complex that may influence glioma formation. Together, these studies will define how developmentally relevant transcriptional mechanisms including gene regulatory elements and chromatin architecture interface to influence glioma biology and reveal novel gene targets potentially regulating gliomagenesis.