Transcriptional Regulation of Early Folliculogenesis

描述（由申请人提供）：卵子发生是卵巢发育、胚胎发生和体内平衡的一个特殊和受调节的过程。这条通路的调节和结构成分的病理变化影响卵巢的分化、维持和早期胚胎发生。对卵子发生中重要的生物修饰因子，特别是那些作用于转录水平的生物修饰因子的基本了解，将进一步加深我们对卵母细胞生物学的理解，并为卵巢早衰、生殖寿命、更年期、卵巢肿瘤和早期胚胎丢失等病理过程提供见解。鉴定和表征在卵母细胞中优先表达的基因将对揭示其卵母细胞特异性功能及其对卵巢病理的贡献非常有用。我们利用来自新生儿卵巢文库的表达序列标签（est）的硅基减法发现了一个在原始卵泡和生长中的卵母细胞中优先表达的新同源盒基因，我们称之为Nobox。Nobox在卵泡发生早期表达，可能在调节哺乳动物卵子发生中起重要作用。为了进一步研究Nobox在卵巢发育中的作用，我们利用同源重组基因靶向的方法获得了Nobox突变等位基因的小鼠纯合子。缺乏Nobox的小鼠卵巢可以形成原始卵泡，但不能生长，到6周龄时，卵巢很小，缺乏可识别的卵泡和卵母细胞。这些卵巢的组织学与卵泡型非综合征性卵巢早衰妇女的卵巢非常相似。我们建议研究Nobox -/-卵巢中阻碍卵泡发育和导致卵母细胞加速丢失的细胞和分子机制。我们将对NOBOX DNA结合位点进行表征，并鉴定受NOBOX直接和间接调控的基因。我们还建议鉴定和分析与NOBOX相互作用的蛋白质。这些研究将有助于增加描述卵母细胞特异性遗传途径的快速增长的信息量，并有助于我们对编码它们的基因突变的病理后果的理解。

DESCRIPTION (provided by applicant): Oogenesis is a specialized and regulated process essential for ovarian development, embryogenesis and homeostasis. Pathologic changes in both regulatory and structural components of this pathway affect ovarian differentiation, maintenance, and early embryogenesis. A basic understanding of the biologic modifiers important in oogenesis, especially those, which act on the transcriptional level, would further our understanding of oocyte biology as well as provide insight into pathologic processes including premature ovarian failure, reproductive life span, menopause, ovarian tumors and early embryonic losses. Identification and characterization of genes preferentially expressed in oocytes will be extremely useful in unraveling their oocyte-specific functions and their contribution to ovarian pathology. We utilized in silico subtraction of expressed sequence tags (ESTs) derived from newborn ovary library to discover a novel homeobox gene preferentially expressed in primordial follicles and growing oocytes, which we call Nobox. Nobox is expressed early in folliculogenesis and may play important roles in regulating mammalian oogenesis. To further study the role of Nobox in ovarian development we generated mice homozygous for the Nobox mutant allele using gene targeting by homologous recombination. Ovaries from mice deficient in Nobox can form primordial follicles but fail to grow and by 6 weeks of age are small and lack discernable follicles and oocytes. The histology of these ovaries closely resembles ovaries from women with afollicular type of non-syndromic premature ovarian failure. We propose to study cellular and molecular mechanisms that block follicular development and cause accelerated loss of oocytes in Nobox -/- ovaries. We will characterize NOBOX DNA binding sites and identify genes regulated directly and indirectly by Nobox. We also propose to identify and analyze proteins that interact with NOBOX. These studies will help add to the rapidly increasing amount of information delineating oocyte-specific genetic pathways and to our understanding of the pathologic consequences of mutations in the genes that encode them.