HIGH RESOLUTION DNASE I HYPERSENSITIVE SITE MAPPING IN MAMMARY GLAND DEVELOPMENT

描述（由申请人提供）：母乳已被证明对婴儿的健康有显著的益处。然而，母乳喂养对婴儿的影响部分取决于母亲乳腺的功能。产奶能力和对健康有益的特定乳汁成分的表达在不同的妇女之间各不相同。这种差异会影响母亲根据建议进行母乳喂养的能力，以及母乳对接受母乳的婴儿的价值。为了解决女性之间的这种关键差异，有必要了解乳腺功能差异产生的潜在机制。这些变异在多大程度上受到发育过程中表观遗传调控的影响尚不清楚。此外，在乳腺中基因表达的表观遗传控制机制尚不清楚。本提案将讨论在乳腺生物学背景下基因表达的表观遗传控制的基本机制。选择该模型有两个原因：首先，因为在乳腺组织中进行工作将使研究结果能够快速应用于临床哺乳问题。其次，使用该模型提供了一个相对容易的系统，在其中观察目标现象。本研究的长期目标是确定表观遗传学和染色质重塑在乳腺和泌乳功能发育中的作用，并确定基因组中作为调控元件的相关区域。具体的假设是，发育和组织特异性基因表达是由近端启动子、远端调控元件和它们所在的染色质协同作用调节的。这是基于文献结果表明：1)远端和近端转录调控因子和染色质的协同作用在发育和分化过程中的基因调控中起着至关重要的作用；2)这些元件具有DNaseI超敏性的特征；3)我们自己的初步数据显示，组织和发育阶段特异性的DNaseI超敏性、组蛋白修饰和启动子的DNA甲基化。与表达相关的远端调控元件和功能未知的进化保守区。本提案的具体目的是确定包含乳腺发育调节基因的大基因组域中乳腺组织和发育阶段特异性dna敏感位点（HS）。我们将使用DNA芯片，一种新的阵列方法，结合DNaseI HS定位和DNA寡核苷酸微阵列，来比较小鼠哺乳期乳腺组织与非哺乳期和非乳腺组织中含有乳蛋白基因和其他发育调节基因的基因组区域。这项研究将有助于我们了解调节乳腺发育和泌乳的因素和途径。牛奶是新生儿营养的主要来源，它为新生儿的健康生长和发育提供了所有必需的成分。然而，我们对建立和维持泌乳所涉及的因素的了解还远远不够完整，特别是DNA的包装如何促进乳腺的发育以及所有相关的调控DNA元件的位置。在这项研究中，我们将在基因组范围内研究这些方面在乳腺组织发育中的作用。这些研究将为理解决定母亲腺体功能的机制提供基础。

DESCRIPTION (provided by applicant): Human milk has been shown to provide significant health benefits to infants. However the impact of human milk feeding for infants depends in part on the functional capacity of the mother's mammary gland. Both milk production capacity and expression of specific milk components that confer health benefits vary between women. This variation impacts the mother's ability to breastfeed according to recommendations and the value of her breast milk to the recipient infant. In order to address this critical variability between women, it is necessary to understand the underlying mechanisms through which variations in mammary gland function arise. The extent to which these variations are influenced by epigenetic regulation during development is unknown. Moreover, mechanisms of epigenetic control of gene expression in the mammary gland are not characterized. This proposal will address basic mechanisms of epigenetic control of gene expression within the context of mammary biology. The model has been chosen for two reasons: first because performing the work in mammary tissue will enable rapid application of findings to clinical lactation questions. Second, use of this model provides a relatively easy system within which to observe the targeted phenomena. The long-term goal of this research is to determine the role epigenetics and chromatin remodeling play in the functional development of the mammary gland and lactation, and to identify the pertinent regions in the genome that function as regulatory elements. The specific hypothesis is that developmental- and tissue-specific gene expression is regulated by the concerted action of proximal promoters, distal regulatory elements and the chromatin in which they reside. This is based on results in the literature demonstrating that 1) the concerted action of distal and proximal transcriptional regulators and chromatin play a crucial role in gene regulation during development and differentiation,2) these elements are characterized by DNaseI hypersensitivity, and 3) our own preliminary data, which show tissue- and developmental stage-specific DNaseI hypersensitivity, histone modification and DNA methylation of promoters, distal regulatory elements and evolutionary conserved regions of unknown function which correlates with expression. The specific aim of this proposal is to determine mammary gland tissue- and developmental stage specific DNaseI hypersensitive sites (HS) in large genomic domains encompassing mammary gland developmentally regulated genes. We will use DNase-chip, a new array approach that combines DNaseI HS mapping with DNA oligo tiling microarrays, to compare lactating mammary gland tissue of the mouse with non-lactating and non-mammary tissue for genomic regions harboring the milk protein genes and other developmentally regulated genes. This study will contribute to our knowledge of the factors and pathways regulating mammary gland development and lactation. Milk is the primary source of nutrition for neonates it provides all the essential components for healthy growth and development of newborns. However, our knowledge of the factors involved in establishing and maintaining lactation is far from complete, in particular how the packaging of the DNA contributes to the development of the mammary gland and the location of all the regulatory DNA elements involved. In this study we will investigate these aspects in developing mammary gland tissue at a genome wide scale. These studies will provide a foundation for understanding the mechanisms that determine the functional capacity of the mother's gland.