Defining transcriptional networks and chromatin conformations regulating glioma tumorigenesis

恶性胶质瘤是最常见和致命的原发性脑肿瘤。尽管目前的治疗 大多数胶质瘤患者在诊断后一年内死亡。基因组不稳定性伴异常 祖细胞群体中细胞命运决定的调节与神经胶质瘤有关，导致这样的观点， 基因突变和发育环境的聚合导致肿瘤发生。最近的调查结果 证明了在神经胶质瘤中大量的发育转录因子被激活。这些研究 表明在神经胶质瘤形成过程中重新利用了控制神经胶质细胞形成的基因调控程序， 指出了神经胶质发育和肿瘤发生的共同转录要求。因此， 我们利用我们对神经胶质细胞发育的理解来获得有价值的生物学见解， 神经胶质瘤的治疗我们以前已经确定了一个胶质细胞生成转录复合物-Sox 9/Brn 2-， 对胶质细胞生成的起始很重要。我们发现，在恶性胶质瘤小鼠模型中， 复合物结合DNA调节元件的能力导致神经胶质起始因子的表达降低， 因子核因子-IA（NFIA）和减少肿瘤发生。我们的初步数据表明， Med12（介体复合物亚基12），在神经胶质细胞发育过程中表达，与染色质连接 与Sox9/Brn2复合物相关，并且与癌症肿瘤发生有关。此外，本发明还 皮质星形胶质细胞培养物中Med12表达的减少损害了 Nfia基因座。因此，我们建议探索胚胎胶质细胞发育与 通过描绘控制胶质瘤的转录电路和调控景观来研究肿瘤发生 肿瘤发生对这些机制的分析有望确定重要的分子靶点， 胶质瘤形成 我们把这个建议集中在一个转录复合物的功能上，这对神经胶质细胞分化很重要， - Sox9/Brn2/Med12-及其在通过基因调控元件协调转录机制中的作用， 和染色质构象。我们将研究Med12在胶质瘤形成中的作用， 和肿瘤细胞生物学，使用广泛的体外和体内技术，在一种新的小鼠恶性肿瘤模型中， 胶质瘤我们将探讨Med12在介导增强子/启动子功能中的机制。 通过利用最近的技术进步， 检查长程染色质相互作用（即3C测定）。我们将在功能上验证下游 Sox9/Brn2/Med12复合物的靶基因可能影响胶质瘤形成。这些研究将 定义发育相关的转录机制，包括基因调控元件， 染色质结构界面影响胶质瘤生物学并揭示潜在调节的新基因靶点 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.