Med12 mechanisms of uterine leiomyoma formation

摘要 子宫平滑肌瘤，更好地称为纤维瘤，是临床上明显的妇女近25 并导致美国妇女的主要发病率，近20万例手术， 切除肌瘤或整个子宫（子宫切除术）。我们和其他团体 利用全外显子组测序将MED 12的外显子2鉴定为突变热点， 平滑肌瘤我们对不同种族的美国女性人群的研究表明，Med 12外显子2 在148例平滑肌瘤中有100例（67%）突变。最常见的人类MED 12突变 美国妇女的平滑肌瘤是一种非同义变体，c.131G>A，预计将取代A。 具有天冬氨酸氨基酸的高度保守的甘氨酸（p.Gly44Asp）。我们创造了新的小鼠模型 其显示在Med 12 c.131G>A核苷酸变体存在下平滑肌瘤形成。发作 Med 12 c.131G>A时，肿瘤形成早，肿瘤体积大 核苷酸变体在Med 12缺陷的子宫间充质背景上表达。条件 子宫间质中Med 12的缺乏不导致肿瘤形成。我们的初步数据是 与Med 12 c.131G>通过功能获得遗传机制起作用的核苷酸变体一致。 在目前的建议中，我们将建立在我们的初步研究，以进一步了解分子 Med 12 c.131G>A核苷酸变异诱导的病理学机制，基因组失衡 以及Med 12 c.131G>A核苷酸变体如何与先前涉及的通路相互作用， 平滑肌瘤形成，如β-连环蛋白、REST和GPR 10。我们建议的三个目标将 检验以下假设：1）Med 12 c.131G>核苷酸变异是一种免疫应答性增益 与平滑肌瘤相关的其他通路协同作用 2）Med 12 c.131G>一个核苷酸变异体破坏DNA结合和整体基因表达 通过组织特异性机制将破坏局限于子宫肌层，和3）Med 12 c.131G>A 在平滑肌瘤中观察到的核苷酸变异通过一组常见的复发性 基因组失衡对Med 12及其在生殖功能中的作用的关注非常重要 鉴于最近的人类研究显示其与子宫平滑肌瘤的相关性， 了解平滑肌瘤。我们已经成功地建立了Med 12突变的小鼠模型， 这导致了令人印象深刻的平滑肌瘤，并很好地复制了人类的状况。我们将使用这个模型 更好地了解Med 12在平滑肌瘤形成中的作用机制。

Abstract Uterine leiomyomas, better known as fibroid tumors, are clinically apparent in almost 25% of women and cause major morbidity to American women with almost 200,000 surgeries performed to either remove the leiomyoma tumors or the whole uterus (hysterectomy). Ours and other groups have utilized whole exome sequencing to identify exon 2 of MED12 as a hotspot of mutations in leiomyomas. Our study on racially diverse population of American women showed that Med12 exon 2 was mutated in 100/148 leiomyomas (67%). The most common human MED12 mutation among leiomyomas of American women is a non-synonymous variant, c.131G>A, predicted to substitute a highly conserved glycine with aspartic amino acid (p.Gly44Asp). We generated novel mouse models that showed leiomyoma formation in the presence of Med12 c.131G>A nucleotide variant. The onset of tumor formation was earlier and the size of these tumors was larger when Med12 c.131G>A nucleotide variant was expressed on Med12 deficient uterine mesenchymal background. Conditional deficiency of Med12 in uterine mesenchyme did not lead to tumor formation. Our preliminary data is consistent with Med12 c.131G>A nucleotide variant acting via a gain of function genetic mechanism. In the current proposal we will build upon our preliminary studies to further understand molecular mechanisms behind Med12 c.131G>A nucleotide variant induced pathology, genomic imbalances and how Med12 c.131G>A nucleotide variant interacts with previously implicated pathways in leiomyoma formation, such as beta-catenin, REST and GPR10. The three aims in our proposal will test the following hypotheses: 1) Med12 c.131G>A nucleotide variant is a hormonally responsive gain of function mutation and interacts synergistically with other pathways implicated in leiomyoma formation, 2) Med12 c.131G>A nucleotide variant disrupts DNA binding and overall gene expression with disruption confined via tissue specific mechanisms to the myometrium and 3) Med12 c.131G>A nucleotide variant drives genomic instability observed in leiomyomas via a common set of recurring genomic imbalances. The focus on Med12 and its role in reproductive function is of great importance given recent human studies showing its association in uterine leiomyomas, including poorly understood leiomyosarcomas. We have successfully generated a mouse model of Med12 mutation that results in impressive leiomyomas and replicates well the human condition. We will use this model to better understand mechanisms behind the Med12 actions in leiomyoma formation.