Fragile X Mental Retardation 1 gene: a master switch of ovarian communication and oocyte quality.

我们最近在牛卵丘卵母细胞复合体中观察到了一种以前未描述的机制，其中RNA颗粒从配子周围的体细胞传递到细胞投射中。我们已经证明，这些货物携带的mRNA可以转移到卵母细胞上。这一点很重要，因为在哺乳动物中从未见过大分子外源性转移到卵母细胞的记录，这是因为突起的尖端不是开放的，缝隙连接只允许小分子(1 KDa)通过。我们已经证明，阻止RNA转移到卵母细胞会极大地影响配子进行和完成减数分裂的能力。因此，我们提出，在横带投射内大型货物的运输和转移是决定卵母细胞质量的一个因素。最近，我们还发现脆性X智力低下蛋白(FMRP)参与了神经元中RNA颗粒的形成和运输。基于卵丘细胞与神经元在结构上有惊人的相似性，以及FMR1(编码FMRP)的失调被认为导致人类不发达的神经元网络和卵巢早衰，推测FMRP通过形成和携带长RNA分子到卵母细胞参与了跨带网络的建立和功能的建立。建议的目标是：*1)检测小鼠和牛的卵泡发生和卵子发生过程中的FMRP和伙伴蛋白；*2)确定TZP网络的质量是否与发育能力有关；*3)确定FMR1在小鼠和牛中的激素调节。使用比较生物学的方法将是非常有用的，以强调通过进化保护的程度，但也解释了这样一个事实，即小鼠的卵子似乎以不同于大型哺乳动物的方式管理它们的母体RNA储备，因为转录沉默的时间更短。这个项目是我最近对生殖生物学领域贡献的合乎逻辑的延续。大多数方法已经在我的实验室建立起来，并得到同行评议出版物的支持。这一发现计划旨在解决一个新的生理过程，并有助于填补关于哺乳动物卵母细胞准备和配子如何获得其发育能力的重要知识空白。

We have recently observed a previously undescribed mechanism in bovine cumulus oocyte complexes where RNA granules transit in the cellular projections from the somatic cells surrounding the gamete. We have shown that these cargos carry mRNAs that can be transferred to the oocyte. This is significant since exogenous transfer of large molecules to the oocyte has never been documented in mammals owing to the fact that the tip of the projections are not open-ended and Gap Junctions only allow the passage of small molecules (<1 kDa). We have shown that prevention of RNA transfer to the oocyte greatly impacts the capacity of the gamete to undertake and complete meiosis. We have therefore proposed that transport and transfer of large cargos within the transzonal projections is a determinant of oocyte quality. Also recently, we have shown that the Fragile-X Mental Retardation Protein (FMRP) is involved in RNA granule formation and transport in neurons. Based on the facts that cumulus cells share striking structural similarities with neurons and that FMR1 (coding for FMRP) dysregulation is known to led to an underdeveloped neuronal network and in premature ovarian insufficiency in human, it is hypothesized that FMRP is involved in the establishment of the transzonal network along with their functionality by forming and carrying long RNA molecules to the oocyte. The proposed objectives are: ***1) to detect FMRP and partner proteins during folliculogenesis and oogenesis in mouse and cattle; ***2) to determine if the quality of the TZP network is associated with developmental competence; ***3) to identify hormonal regulators of FMR1 in mouse and cattle. The use of a comparative biology approach will be very informative to highlight the extent of conservation through evolution but also to account for the fact that mouse eggs seems to manage their maternal RNA reserves differently than large mammals since the period of transcriptional silence is shorter. This project is a logical continuation of my recent contributions to the field of reproductive biology. Most of the methods are already established in my laboratory and supported by peer reviewed publications. This discovery program is aimed to tackle a novel physiological process and to contribute to filling the important knowledge gap existing about oocyte preparation and how the gamete acquires its developmental competence in mammals.