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先前未描述的机制，其中RNA颗粒在配子周围体细胞的细胞投射中运输。我们已经证明这些货物携带可以转移到卵母细胞的mrna。这是很重要的，因为在哺乳动物中，由于突起的尖端不是开放式的，并且间隙连接只允许小分子（<1 kDa）通过，因此从未记录过大分子向卵母细胞的外源性转移。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，跨区投射内大型货物的运输和转移是卵母细胞质量的决定因素。最近，我们发现脆性- x智力迟钝蛋白（FMRP）参与神经元中RNA颗粒的形成和运输。基于丘细胞与神经元具有惊人的结构相似性，以及已知FMR1（编码FMRP）失调导致神经网络发育不全和人类卵巢早衰的事实，我们假设FMRP通过形成并携带长RNA分子到卵母细胞参与跨区网络的建立及其功能。目的：***1)在小鼠和牛的卵泡发生和卵子发生过程中检测FMRP和伴侣蛋白；***2)确定TZP网络的质量是否与发展能力相关；***3)在小鼠和牛中鉴定FMR1的激素调节因子。比较生物学方法的使用将非常有用，以突出通过进化的保护程度，但也解释了这样一个事实，即小鼠卵子似乎管理其母体RNA储备的方式不同于大型哺乳动物，因为转录沉默期较短。这个项目是我最近在生殖生物学领域的贡献的一个合乎逻辑的延续。我的实验室已经建立了大多数方法，并得到了同行评审出版物的支持。这一发现项目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制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.