RPG: Mechanisms of Integrin Gene Regulation during Trophoblast Differentiation

Sutherland 9707692，这项研究的总体目标是了解在植入小鼠胚胎中调节滋养细胞分化的分子机制。在达到囊胚期后，哺乳动物胚胎必须发展成外部的营养来源，才能继续发育。小鼠胚胎通过植入子宫基质并与母体血液供应形成连接来实现这一过程，这一过程是由一种被称为滋养层细胞的特殊细胞群介导的。滋养层细胞有许多功能：它们将胚胎固定在子宫基质中，它们形成连接母体系统的血管，将营养丰富的血液引导到胚胎的外围，它们分泌激素，改变母体内分泌系统以维持怀孕，它们构成最终的绒毛尿囊状胎盘的一部分。滋养层细胞对胚胎的进一步发育是绝对必要的；它们是哺乳动物发育过程中建立的第一个谱系，只有在它们成功分化后，胚胎谱系才开始发育。因此，了解滋养细胞分化的过程是很重要的，这既是从更多地了解这些细胞本身的角度，也是从理解胚胎发育中的关键调控事件的角度。滋养细胞功能的一个主要方面是与子宫细胞外基质的侵袭性相互作用；为了促进这一点，它们表达一系列独特的整合素家族的细胞外基质受体。几个整合素受体亚基的表达与滋养层细胞的分化有关：两个亚基在承诺时首先表达((7，(6))，而另外两个亚基((1，(6))的表达在侵袭开始时受到相对调节。尽管它们对发育很重要，但人们对控制它们分化的分子机制知之甚少。正在测试的假设是，特定转录因子对这些(和其他)启动子的发育调节作用导致上皮性滋养外胚层细胞分化为侵袭性滋养层巨细胞。整个赠款的具体目标将是1)。鉴定在滋养层细胞分化不同阶段特异表达的整合素基因启动子，2)。定义调节其表达的转录因子，以及3)。确定在围着床期发育阶段控制其活性和/或表达的外部因素。为了准备完整的研究提案，提出了规划期的以下目标：1)。克隆并鉴定整合素a1和a6亚基的启动子区域；检测克隆区域在大鼠滋养层细胞系Rcho-1中定向表达滋养层细胞的能力。了解整合素基因调控滋养层细胞分化的机制将有助于更广泛地了解滋养层细胞分化的过程，为探索滋养层细胞运动的发育调控以及更广泛的侵袭行为的细胞机制提供新的工具。

Sutherland 9707692 The overall goal of this research is to understand the molecular mechanisms that regulate trophoblast differentiation in the implanting mouse embryo. After reaching the blastocyst stage, the mammalian embryo must develop an external source of nutrients in order to continue its development. The mouse embryo accomplishes this by implanting into the stroma of the uterus and forming connections with the maternal blood supply, a process that is mediated by a specialized population of cells known as trophoblast. Trophoblast cells have many functions: they anchor the embryo in the uterine stroma, they form blood vessels that connect with the maternal system and direct nutrient-rich blood to the periphery of the embryo, they secrete hormones that redirect the maternal endocrine system to maintain the pregnancy, and they form part of the definitive chorioallantoic placenta. Trophoblast cells are absolutely essential for the further development of the embryo; they are the first lineage to be established during mammalian development, and it is only after they have successfully differentiated that the embryonic lineages begin to develop. Therefore, it is important to understand the process of trophoblast differentiation, both from the standpoint of knowing more about these cells themselves, but also from the standpoint of understanding a critical regulatory event in the development of the embryo. A major aspect of trophoblast function is invasive interaction with the extracellular matrix of the uterus; to facilitate this they express a unique repertoire of extracellular matrix receptors of the integrin family. The expression of several integrin receptor subunits is associated with trophoblast differentiation: two subunits are first expressed at the time of commitment ((7, (6), while the expression of two others ((1, (6) is appositely regulated at the onset of invasion. Very little is known about the molecular mechanisms that control their differentiation, despite their importance to d evelopment. The hypothesis being tested is that the developmentally regulated action of specific transcription factors on these (and other) promoters results in the differentiation of epithelial trophectoderm cells into invasive trophoblast giant cells. The specific aims of the overall grant will be 1). to characterize the promoters of integrin genes that are specifically expressed at different stages of trophoblast differentiation, 2). to define the transcription factors that regulate their expression, and 3). to identify the external factors that control their activity and/or expression during the peri-implantation stages of development. In order to prepare for the full research proposal, the following aims are proposed for the planning period: 1). to clone and identify the promoter regions of the integrin al and a6 subunits, and 2). to test the ability of the cloned regions to direct trophoblast-specific expression in the rat trophoblast cell line Rcho-1. Understanding the mechanisms underlying integrin gene regulation in differentiating trophoblast will provide a broader understanding of the process of trophoblast differentiation as well as new tools with which to probe the the developmental regulation of trophoblast motility, and the cellular mechanisms underlying invasive behavior more generally.