Med12 mechanisms of uterine leiomyoma formation

摘要 子宫肌瘤，更为人所知的是子宫肌瘤，临床上几乎25%的女性都有这种症状。 给美国妇女造成了严重的发病率，因为有近200,000例手术是为了 切除子宫肌瘤或全子宫(子宫切除术)。我们和其他组织都有 利用全外显子测序鉴定MED12基因外显子2为突变热点 肌瘤。我们对不同种族的美国女性人群的研究表明，MED12外显子2 148例子宫肌瘤中有100例发生突变(67%)。其中最常见的人类MED12突变 美国女性的肌瘤是一种非同义变异，c.131G&gt；A，预计将取代a 高度保守的甘氨酸和天冬氨酸氨基酸(p.Gly44Asp)。我们创造了新的老鼠模型 这表明在存在MED12 c.131G&gt；A核苷酸变异的情况下会形成肌瘤。一开始 当MED12 c.131G&GT；A时，肿瘤的形成更早，肿瘤的大小更大 核苷酸变异体在MED12缺乏的子宫间充质背景中表达。有条件的 子宫间充质中MED12的缺失不会导致肿瘤的形成。我们的初步数据是 与MED12 c.131G和GT一致；一种通过功能遗传机制获得作用的核苷酸变体。 在目前的提案中，我们将在初步研究的基础上进一步了解分子 MED12 C.131G和GT；A核苷酸变异引起的病理和基因组失衡的机制 以及MED12 C.131G和GT；A核苷酸变体如何与先前涉及的途径相互作用 平滑肌瘤的形成，如β-连环素、REST和GPR10。我们提案中的三个目标将 检验以下假设：1)MED12 c.131G&GT；核苷酸变体是一种激素反应收益 与其他与肌瘤有关的通路协同作用 形成，2)MED12 c.131G和GT；一种核苷酸变体扰乱DNA结合和整体基因表达 3)MED12 c.131G&gt；A 核苷酸变异通过一组常见的复发基因驱动子宫肌瘤的基因组不稳定性 基因组不平衡。关注MED12及其在生殖功能中的作用是非常重要的 鉴于最近的人类研究表明它与子宫肌瘤的相关性，包括 明白了平滑肌肉瘤。我们已经成功地建立了MED12突变的小鼠模型 这会导致令人印象深刻的肌瘤，并很好地复制了人类的情况。我们将使用此模型 为了更好地了解MED12在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.