Investigation of the Tip60-p400 complex role in embryonic stem cell self-ren

描述（由申请人提供）：多细胞生物由数百种不同的细胞类型组成，每种细胞类型都具有独特的基因表达模式。不同的细胞类型必须稳定地维持指定细胞类型的转录模式，但具有足够的可塑性，以允许基因表达的改变，这是分化或对环境变化的反应所必需的。这些不同表达模式的建立和维持对细胞身份和有机体生存至关重要，因为单个细胞中的异常基因表达可能导致发育异常或癌症。我们使用小鼠胚胎干细胞（ESCs）来研究用于调节哺乳动物细胞基因表达的分子机制。ESCs具有多能性，能够分化为构成发育和成年生物体的每种细胞类型。当ESCs在适当的条件下培养时，它们会继续自我更新，或在多能状态下无限增殖。一些转录因子，如Oct4、Nanog、Sox2、Foxd3和Stat3，对于自我更新和多能性是必不可少的。虽然人们认为染色质结构水平的调控在ESC自我更新和多能性中也很重要，但染色质调控蛋白在这些过程中的作用仍然知之甚少。在这里，我们建议研究Tip60-p400组蛋白乙酰转移酶-染色质重塑复合体在ESC自我更新中的作用。我们的初步结果表明，tip60-p400与多能性转录因子Nanog合作，维持esc特异性表达谱，促进自我更新和多能性。我们的研究将集中于了解Tip60-p400复合物与Nanog之间功能相互作用的分子性质。最后，我们的初步结果暗示了第二种染色质重塑复合体，即在ESC自我更新中含有brg1的Swi/Snf复合体。我们还将研究该复合物调节esc特异性基因表达谱的机制。

DESCRIPTION (provided by applicant): Multicellular organisms consist of hundreds of different cell types, each of which is characterized by a unique pattern of gene expression. Different cell types must stably maintain the transcriptional patterns that specify that cell type, yet have sufficient plasticity to allow the alterations in gene expression that are necessary for differentiation or responses to environmental changes. Establishment and maintenance of these diverse expression patterns is fundamentally important for cell identity and organismal survival, since aberrant gene expression in a single cell can lead to developmental abnormalities or cancer. We use mouse embryonic stem cells (ESCs) to study the molecular mechanisms that are used to regulate gene expression in mammalian cells. ESCs are pluripotent, with the ability to differentiate into every cell type that makes up the developing and adult organism. ESCs continue to self-renew, or indefinitely proliferate in the pluripotent state, when they are cultured under appropriate conditions. Several transcription factors, such as Oct4, Nanog, Sox2, Foxd3, and Stat3, are essential for self-renewal and pluripotency. While it is thought that regulation at the level of chromatin structure is also important in ESC self-renewal and pluripotency, the role of chromatin regulatory proteins in these processes remains more poorly understood. Here we propose to investigate the role of the Tip60-p400 histone acetyltransferase-chromatin remodeling complex in ESC self-renewal. Our preliminary results indicate that tip60-p400 cooperates with the pluripotency transcription factor Nanog to maintain the ESC-specific expression profile that promotes self-renewal and pluripotency. Our studies will focus on understanding the molecular nature of the functional interaction between the Tip60-p400 complex and Nanog. Finally, our preliminary results implicate a second chromatin remodeling complex, the Brg1-containing Swi/Snf complex in ESC self-renewal. We will also investigate the mechanisms by which this complex regulates the ESC-specific gene expression profile. PUBLIC HEALTH RELEVANCE: Embryonic stem cells can grow indefinitely as an established cell line, a process referred to as self-renewal. ESCs are highly proliferative in their undifferentiated state. In contrast, somatic stem cells, such as hematopoietic stem cells, grow more slowly than ESCs and do not expand without significant accompanying differentiation. ESCs are also pluripotent - they have the ability to differentiate into all cell types. Because of these properties, ESCs are regarded as a major potential source of material for stem cell therapies. However, the molecular mechanisms governing self-renewal and pluripotency are largely unknown. A better molecular understanding at the factors that induce and maintain the stem cell state ESCs is essential for moving towards the implementation of ESC-based therapies. We employ mouse ESCs to understand the role of chromatin regulatory proteins, which regulate gene expression by affecting the accessibility of the DNA template, in ESC self-renewal and pluripotency. These studies will have important impacts on the development of ESC lines for stem-cell based therapies.