Programming the oocyte for the next generation

为下一代的卵母细胞进行编程

• 批准号: RGPIN-2014-06628
• 负责人: Sirard, Marc
• 金额: $ 6.99万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=589127
• 关键词: Programming; oocyte; next; generation

This research program is focused on the most extraordinary cell of the body: the oocyte. Indeed this cell has unique capacities as, in the weeks preceding ovulation, it accumulates instructions in order to control/allow early embryonic development following fertilization. This exceptional phenomenon is the focus of this research program. We know that somehow, the ovary controls the quality of the oocyte, which is demonstrated by its ability to become an embryo. However, the signal transduction processes originating in the ovary and the oocyte molecular response to these signals are not characterized. Oocytes may have different levels of quality depending on the size and differentiation level of the follicles of origin. We believe that there is a cascade of events triggered by follicular differentiation that indicates to the oocyte the trajectory to follow: ovulation or atresia. In cows for example, drugs are used to stimulate the ovulation of several eggs to accelerate the dissemination of good genetics but although we have developed pharmaceutical interventions that generate good embryos, the mechanisms controlling quality acquisition remain elusive. With quite a unique collection of follicular samples, we have generated a tremendous amount of data allowing for the creation of a virtual folliculome that aims to capture the complexity of the follicle differentiation. Using unique specific hormone-induced follicular contexts associated with good yields of embryos, we have identified molecules secreted by granulosa cells that may impact the differentiation of cumulus cells and the oocyte in the last days prior to ovulation. There is now an opportunity to assemble the puzzle of oocyte competence using omics, bioinformatics and in vitro models and we believe that we are rightly positioned to achieve that. Using state-of-the-art molecular tools such as transcriptomics and bioinformatics, it is now possible to explore the gene regulation and expression in follicles starting with granulosa cells moving on to cumulus cells and finally to oocytes in a continuum. The actual challenge of functional genomics is the organisation of the data into a physiological and relevant context. This program is interested in the follicular signaling to the oocyte and the special maternal instructions that are imbedded in the egg and that direct the development of a good embryo and a healthy calf. We already have exclusive data which generated several hypotheses to be validated. Our studies indicate that one of the events that could initiate the follicular signaling to the oocyte is the development of the capacity of the follicle to ovulate, which occurs concomitantly with the appearance of LH receptors on granulosa cells, and continues with the switch of these cells from an epithelial type to the mesenchymal type found in the corpus luteum. Different models are available in our lab to study the relevant changes in signaling cascade; 1) in vitro primary cultures of granulosa cells to assess individual gene effects on downstream targets, 2) signal induction or mimicking during culture of cumulus-enclosed immature oocytes and 3) oocyte microinjection with morpholinos or specific reporter RNAs with regulatory 3’UTR or chemical agonists to validate the pathway identified. With all the exceptional data that we have accumulated, the tools we have built or acquired through collaboration and the models that we propose, we hope to unravel the specific molecular sequence of events that makes a good egg in dairy cows. This functional understanding will allow direct and indirect interventions in dairy cow’s reproduction and help to maintain the leadership position that our industry has gained over the years.

这个研究项目的重点是人体中最不寻常的细胞：卵母细胞。事实上，这个细胞具有独特的能力，因为在排卵前几周，它积累指令，以控制/允许受精后的早期胚胎发育。这一特殊现象是本研究项目的重点。我们知道，卵巢在某种程度上控制着卵母细胞的质量，这可以通过它成为胚胎的能力来证明。然而，起源于卵巢的信号转导过程和卵母细胞对这些信号的分子反应尚未被描述。卵母细胞的质量水平取决于原始卵泡的大小和分化水平。我们认为，卵泡分化触发了一连串的事件，向卵母细胞指示排卵或闭锁的轨迹。例如，在奶牛中，药物被用来刺激几个卵子的排卵，以加速良好基因的传播，但尽管我们已经开发出产生良好胚胎的药物干预措施，但控制质量获得的机制仍然难以捉摸。有了相当独特的卵泡样本收集，我们已经产生了大量的数据，允许创建一个虚拟卵泡组，旨在捕捉卵泡分化的复杂性。利用与胚胎高产率相关的独特的激素诱导卵泡环境，我们已经确定了颗粒细胞分泌的分子，这些分子可能在排卵前的最后几天影响积云细胞和卵母细胞的分化。现在有机会利用组学、生物信息学和体外模型来组装卵母细胞能力的难题，我们相信我们有正确的定位来实现这一目标。