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

描述(申请人提供)：多细胞生物体由数百种不同的细胞类型组成，每种类型的细胞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该细胞类型的转录模式，但又具有足够的可塑性，以允许分化或对环境变化的反应所必需的基因表达的变化。建立和维持这些不同的表达模式对细胞特性和生物生存至关重要，因为单个细胞中异常的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)来研究用于调控哺乳动物细胞中基因表达的分子机制。胚胎干细胞是多能的，有能力分化为组成发育中和成年有机体的每一种细胞类型。当胚胎干细胞在适当的条件下培养时，它们会继续自我更新，或在多能性状态下无限增殖。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。尽管染色质结构水平的调控在胚胎干细胞的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特异性的表达谱，促进自我更新和多能性。我们的研究将集中在了解Tip60-P400复合体与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ESC自我更新中的第二个染色质重塑复合体，即含有BRG1的Swi/SNF复合体。我们还将研究该复合体调节ESC特异性基因表达谱的机制。 与公共卫生相关：胚胎干细胞可以作为已建立的细胞系无限生长，这一过程被称为自我更新。胚胎干细胞在其未分化状态下高度增殖。相比之下，体细胞干细胞，如造血干细胞，生长速度比ESCs慢，在没有明显伴随分化的情况下不会扩张。胚胎干细胞也是多能的--它们有能力分化成所有类型的细胞。由于这些特性，胚胎干细胞被认为是干细胞治疗的主要潜在材料来源。然而，调控自我更新和多能性的分子机制在很大程度上是未知的。对诱导和维持干细胞状态的因素有更好的分子理解，对于以干细胞为基础的治疗的实施至关重要。我们利用小鼠胚胎干细胞来了解染色质调节蛋白在胚胎干细胞自我更新和多能性中的作用，染色质调节蛋白通过影响DNA模板的可及性来调节基因的表达。这些研究将对干细胞疗法的胚胎干细胞系的发展产生重要影响。

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.