Endocrine disruption of myometrial stem cell activities

描述（由申请人提供）：在正常哺乳动物生殖寿命期间，成年子宫在小鼠的发情周期（或灵长类动物的月经周期）中多次经历对激素信号的“损伤和修复”的重复循环，以及在妊娠期间，当它增长10倍以容纳胎儿时。虽然这种重塑过程对生殖至关重要，但所涉及的分子机制在很大程度上是未知的，特别是在灵长类动物中，子宫内膜的顶层每个月都会脱落和再生。主要研究者已经表明，苗勒管间充质中的<$-连环蛋白的条件性缺失导致子宫肌层中的子宫平滑肌细胞被脂肪组织进行性替代。他们还表明，与条件性表达的功能获得性等位基因的<$-连环蛋白的匡威实验导致子宫肌层平滑肌增生和基质肉瘤和平滑肌瘤（子宫肌瘤）的发展。这两种表型仅在小鼠进入性成熟后观察到，表明这些小鼠中被破坏的机制受到卵巢类固醇激素的调节。主要研究人员假设，在子宫肌层干细胞中，连环蛋白（在许多干细胞微环境中是干细胞的关键决定因素）的核功能的破坏导致了这些子宫病变。他们已经在小鼠和人类中鉴定了再生的子宫肌层平滑肌干细胞，并提出研究内分泌干扰物是否（1）在体外和体内循环、妊娠和平滑肌瘤发育期间影响子宫肌层干细胞的分化和多能性;（2）在我们的功能获得和功能丧失模型中失调Wnt/<$-连环蛋白信号传导的分子机制;以及（3）在子宫肌层发育的围产期窗口期间改变子宫肌层干细胞的分化和多能性。这些实验的结果将有助于确定内分泌干扰物是否对子宫肌层干细胞的分化和功能有显著影响。在Wnt/<$-连环蛋白信号失调的独特小鼠模型中进行这些实验也将有助于确定在正常和条件性破坏的分化期间以及在子宫肌层干细胞的成体活动中，<$-连环蛋白所使用的分子机制中的哪一种受到影响。主要研究者预测，环境相关水平的内分泌干扰物暴露在子宫生物学中起着重要作用，特别是在子宫肌层干细胞水平及其对子宫肌瘤病因学和病理生理学的贡献。 公共卫生相关性：子宫肌瘤折磨着大约20%的美国妇女在他们的生育年龄，是盆腔疼痛，异常子宫出血和不孕症的重要来源。子宫肌瘤也是美国子宫切除术的主要原因。尽管子宫肌瘤造成了重大的医疗负担，但对其原因或最佳治疗策略知之甚少。拟议研究的总体目标是了解环境暴露于内分泌干扰化合物（EDCs）对负责子宫肌瘤发展的干细胞的影响，并确定干细胞水平的治疗干预是否可以导致这种疾病的更好管理策略。

DESCRIPTION (provided by applicant): The adult uterus undergoes repeated cycles of "injury and repair" in response to hormonal signals during the estrous cycle in mice (or the menstrual cycle in primates) numerous times in a normal mammalian reproductive lifespan, as well as during pregnancy when it grows ten-fold to accommodate the fetus. Although this process of remodeling is essential for reproduction, the molecular mechanisms involved are largely unknown, particularly in primates where the top layer of the endometrium is shed and regenerated every month. The principal investigators have shown that conditional deletion of ¿-catenin in the Mullerian duct mesenchyme results in a progressive replacement of uterine smooth muscle cells in the myometrium with adipose tissue. They have also shown that the converse experiment with conditional expression of a gain-of-function allele of ¿-catenin results in myometrial smooth muscle hyperplasia and development of stromal sarcomas and leiomyoma's (uterine fibroids). Both phenotypes were observed only after mice entered sexual maturity, suggesting that the mechanisms disrupted in these mice are regulated by ovarian steroid hormones. The principal investigators hypothesize that disruption of the nuclear function of ¿-catenin, a key determinant of stemness in many stem cell microenvironments, in myometrial stem cells leads to these uterine pathologies. They have identified the regenerative myometrial smooth muscle stem cells in mice and in humans and propose to investigate whether endocrine disruptors (1) impact the differentiation and pluripotency of myometrial stem cells in vitro and in vivo during cycling, pregnancy, and leiomyoma development; (2) dysregulate the molecular mechanisms of Wnt/¿-catenin signaling in our gain-of-function and loss-of-function models; and (3) alter the differentiation and pluripotency of myometrial stem cells during the perinatal window of myometrial development. The results of these experiments will help determine whether endocrine disruptors have a significant impact on the differentiation and function of myometrial stem cells. Performing these experiments in unique mouse models of dysregulated Wnt/¿-catenin signaling will also help determine which of the molecular mechanisms used by ¿-catenin, during normal and conditionally disrupted differentiation and in the adult activities of the myometrial stem cells, are affected. The principal investigator predict that an environmentally relevant level of exposure to endocrine disruptors plays an important role in uterine biology, particularly at the myometrial stem cell level and its contribution to uteine fibroid etiology and pathophysiology. PUBLIC HEALTH RELEVANCE: Uterine fibroids afflict approximately 20% of American women during their reproductive years and are a significant source of pelvic pain, abnormal uterine bleeding, and infertility. Uterine fibroids are also the major reason for hysterectomies in the United States. Despite the major health care burden posed by uterine fibroids, very little is known about their cause or the best treatment strategies. The overall aims of the proposed studies are to understand the effects of environmental exposure to endocrine-disrupting compounds (EDCs) on the stem cells that are responsible for uterine fibroid development and determine whether therapeutic intervention at the stem cell level can lead to better management strategies for this disease.