Oct-4 Regulates Embryonal Carcinoma Differentiation

描述（由申请人提供）：转移性胚胎癌（一种生殖细胞肿瘤（GCT））的一个有趣特征是它们能够分化为局部畸胎瘤，其由所有三种胚胎谱系（外胚层、中胚层和内胚层）的更成熟、生长较慢的组织组成。胚胎癌的分化是由调节基因控制的，这些基因介导永久性的表型改变。这些调节基因通常是转录调节因子，其激活或抑制基因表达模式，从而产生干细胞分化期间所见的表型变化。这些转录因子不仅可以在GCT的特定分化阶段期间介导表型成熟，而且还可以调节在分化的下一阶段中重要的转录因子的表达。这项资助的目的是增加对EC细胞中存在的转录因子如何调节EC细胞在第一次分化时做出的初始谱系决定的理解。POU同源结构域蛋白Oct-4和我们分离的叉头盒蛋白FoxD 3（以前的Genesis）是优先在EC细胞中表达的转录因子。在EC细胞的正常胚胎等价物胚胎干（ES）细胞中，在原肠胚形成期间下调Oct-4对于适当的谱系发育是必需的。我们之前已经发现Oct-4也可以作为一个辅助阻遏物，阻止FoxD 3激活分化转录因子FoxA 1和2的启动子。本研究将探讨Oct-4和FoxD 3在EC细胞分化决定中的作用，具体目标有三个。1)Oct-4和FoxD 3之间的相互作用结构域将被定位，并在真实的时间蛋白质组学中分析其功能。2)将研究Oct-4抑制谱系特异性转录激活的生化机制。3)将研究Oct-4的阻遏物活性如何介导EC细胞中对畸胎瘤分化的全能性。

DESCRIPTION (provided by applicant): An intriguing characteristic of metastatic embryonal carcinoma, a type of germ cell tumor (GCT), is that they are able to differentiate to localized teratoma, which is made up of more mature, slower growing tissue of all three embryonic lineages, ectoderm, mesoderm, and endoderm. Differentiation of embryonal carcinoma (EC) is controlled by regulatory genes that mediate permanent phenotypic change. These regulatory genes are often transcriptional regulators that activate or repress patterns of gene expression that create the phenotypic change seen during stem cell differentiation. These transcription factors can not only mediate phenotypic maturation during a particular differentiation stage of GCT, but can also regulate expression of the transcription factors that are important in the next stage of differentiation. The goal of this grant is to increase understanding how the transcription factors present in the EC cell regulate the initial lineage decisions an EC cells makes as it first differentiates. The POU homeodomain protein Oct-4 and the Forkhead Box protein we isolated, FoxD3 (previously Genesis), are transcription factors preferentially expressed in EC cells. In the normal embryonic equivalent of EC cells, embryonic stem (ES) cells, downregulation of Oct-4 during gastrulation is essential for proper lineage development. We have previously found that Oct-4 can also act as a co-repressor to prevent FoxD3 from activating the promoters of the differentiation transcription factors FoxA1 and 2. This study will investigate the role of Oct-4 and FoxD3 in EC cell differentiation decisions in three specific aims. 1) The interacting domains between Oct-4 and FoxD3 will be mapped and their function analyzed in real time proteomics. 2) The biochemical mechanism by which Oct-4 represses lineage-specific transcriptional activation will be investigated. 3) How the repressor activity of Oct-4 mediates totipotentiality versus teratoma differentiation in EC cells will be studied.