Oct-4 Regulates Embryonal Carcinoma Differentiation

描述（由申请人提供）：转移性胚胎癌是一种生殖细胞肿瘤（GCT），其一个有趣的特征是它们能够分化为局部畸胎瘤，该畸胎瘤由三种胚胎谱系（外胚层、中胚层和内胚层）中更成熟、生长较慢的组织组成。胚胎癌（EC）的分化是由介导永久性表型变化的调控基因控制的。这些调节基因通常是转录调节因子，激活或抑制在干细胞分化过程中产生表型变化的基因表达模式。这些转录因子不仅可以介导GCT特定分化阶段的表型成熟，还可以调节下一阶段分化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细胞首次分化时的初始谱系决定的理解。我们分离的POU同源结构域蛋白Oct-4和Forkhead Box蛋白FoxD3（之前的Genesis）是在EC细胞中优先表达的转录因子。在EC细胞，胚胎干（ES）细胞的正常胚胎等效物中，在原肠胚形成过程中下调Oct-4对于正常的谱系发育至关重要。我们之前发现Oct-4也可以作为一种共同抑制因子，阻止FoxD3激活分化转录因子FoxA1和2的启动子。本研究将从三个方面探讨Oct-4和FoxD3在EC细胞分化决策中的作用。1)绘制Oct-4与FoxD3的相互作用结构域，并实时分析其功能。2)研究Oct-4抑制谱系特异性转录激活的生化机制。3) Oct-4抑制因子活性如何介导EC细胞的全潜能与畸胎瘤分化有待进一步研究。

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.