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一种以前未描述的机制，其中RNA颗粒在配子周围体细胞的细胞突起中转运。我们已经证明，这些货物携带的mRNA可以转移到卵母细胞。这是重要的，因为在哺乳动物中从未记录过大分子向卵母细胞的外源性转移，这是由于突起的尖端不是开放式的，并且间隙连接仅允许小分子（<1 kDa）通过。我们已经证明，阻止RNA转移到卵母细胞极大地影响了配子进行和完成减数分裂的能力。因此，我们提出，运输和转移的大型货物内的transzonal投影是卵母细胞质量的决定因素。最近，我们还发现脆性X智力迟钝蛋白（FMRP）参与神经元中RNA颗粒的形成和运输。基于卵丘细胞与神经元具有惊人的结构相似性以及已知FMR 1（编码FMRP）失调导致神经元网络发育不全和人类卵巢功能不全的事实，推测FMRP通过形成长RNA分子并将其携带至卵母细胞而参与跨带网络的建立沿着其功能。拟议的目标是：*1）在小鼠和牛的卵泡发生和卵子发生期间检测FMRP和伴侣蛋白; *2）确定TZP网络的质量是否与发育能力相关; *3）鉴定小鼠和牛中FMR 1的激素调节剂。比较生物学方法的使用将是非常翔实的，以突出的程度，通过进化的保护，但也占的事实，即小鼠卵子似乎管理其母体RNA储备不同的大型哺乳动物，因为转录沉默的时间较短。这个项目是我最近在生殖生物学领域的贡献的逻辑延续。大多数方法已经在我的实验室建立，并得到同行评审出版物的支持。该发现计划旨在解决一种新的生理过程，并有助于填补有关卵母细胞制备以及配子如何在哺乳动物中获得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.