REGULATION OF NANOG IN DNA DAMAGE RESPONSE, DEVELOPMENT AND TUMORIGENESIS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 胚胎干细胞（ESC）能够无限自我更新，并保留多能性以分化成体内所有细胞谱系。由于ESC经历稳健的细胞增殖并且在正常细胞增殖期间发生DNA损伤，因此ESC具有严格的机制来维持遗传稳定性以防止DNA损伤传递到后代是至关重要的。与这一观点相一致，ESCs中的自发突变率比体细胞低得多。维持胚胎干细胞遗传稳定性的机制尚不清楚。我推测，去除DNA损伤的ESCs的一个主要机制是诱导它们分化为其他细胞类型，以保持ESCs自我更新库的遗传完整性。最近发现的同源结构域蛋白Nanog作为自我更新的主调节器允许我们测试这一假设。我们假设Nanog的表达和活性可能在DNA损伤时受到抑制。为了支持这一观点，我们最近的研究结果表明，DNA损伤通过抑制Nanog表达诱导ESCs分化。肿瘤抑制因子p53是这一过程所必需的，并通过直接结合其启动子来抑制Nanog的表达。我提出了三个目标，以进一步阐明DNA损伤后和ESC分化过程中Nanog的表达和活性的调节，并研究Nanog在癌症中的潜在作用。目标1。阐明Nanog在小鼠和人ESCs中p53家族成员依赖性下调的生理重要性。目标二。DNA损伤后通过ESCs中蛋白质-蛋白质相互作用调节Nanog活性。目标3。研究Nanog在发育、遗传稳定性和肿瘤发生中的作用。这些研究与人类健康直接相关。在这种情况下，Nanog在肿瘤发生中的潜在作用的研究将有助于开发新的治疗Nanog过表达的癌症，包括生殖细胞肿瘤和乳腺癌。此外，这些研究将揭示维持人类胚胎干细胞遗传稳定性的机制，这对未来的人类细胞/组织替代疗法具有巨大潜力。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Embryonic stem cells (ESCs) are capable of unlimited self-renewal and retain the pluripotency to differentiate into all cell lineages in the body. Since ESCs undergo robust cellular proliferation and DNA damage occurs during normal cellular proliferation, it is critical for ESCs to possess stringent mechanisms to maintain genetic stability to prevent the passage of DNA damage to the progeny. Consistent with this notion, the spontaneous mutation rate is much lower in ESCs than in somatic cells. The mechanism to maintain genetic stability in ESCs remains unclear. I hypothesize that one primary mechanism to rid of DNA damaged-ESCs is to induce their differentiation into other cell types in order to maintain the genetic integrity of the self-renewing pool of ESCs. Recent discovery of the homeodomain protein Nanog as the master regulator of self-renewal allows us test this hypothesis. We hypothesized that the expression and activities of Nanog might be suppressed in response to DNA damage. In support of this notion, our recent findings indicate that DNA damage induces the differentiation of ESCs by suppressing the Nanog expression. Tumor suppressor p53 is required for this process and suppresses the expression of Nanog by direct binding to its promoter. I propose three aims to further elucidate the regulation of the expression and activity of Nanog after DNA damage and during ESC differentiation, and to study the potential roles of Nanog in cancers. Aim 1. To elucidate physiological importance of p53 family members-dependent downregulation of Nanog in mouse and human ESCs. Aim 2. Regulation of Nanog activities through protein-protein interaction in ESCs after DNA damage. Aim 3. To study the roles of Nanog in development, genetic stability and tumorigenesis. These studies have direct relevance to human health. In this context, the studies of the potential role of Nanog in tumorigenesis will help to develop new therapy for Nanog-overexpressing cancers, including germ cell tumors and breast carcinomas. In addition, these studies will shed light on mechanism that maintains genetic stability in human ESCs, which have a great potential for future human cell/tissue replacement therapy.