Programming the oocyte's legacy

这个研究项目是通过牛的卵母细胞来探索代际编程。三十年来，我们的实验室一直致力于了解牛卵母细胞的质量。我们最近的发现表明卵泡细胞周围的代谢环境是质量控制过程的主要决定因素，以确保产生一个有活力的卵母细胞。我们还发现，通过卵母细胞传递的信息不仅对产生一个有活力的胚胎很重要，而且影响未来个体的代谢程序。这种表观遗传现象正在成为哺乳动物生殖研究的新范式，我们在这一领域做出了重大贡献。我们发现母亲（奶牛）和父亲（公牛）都通过非遗传机制（DNA甲基化、微rna和组蛋白改变或保留）将配子信息传递给胚胎。我们的假设是，卵泡环境或体外培养条件对卵母细胞传递给下一代的代谢程序依赖于表观遗传机制，这种机制受到卵泡环境或体外培养条件的高度影响。为了验证这一假设，我们的第一个目标是评估调节能量代谢调节剂（脂质、糖和代谢物）在牛卵母细胞体外成熟（IVM）过程中的影响，并根据产后奶牛的生理状况产生囊胚。考虑到积云细胞的重要性，我们的第二个目标是研究积云细胞对代谢应激的急性反应，以了解它如何改变提供给卵母细胞的信息和营养物质，然后跟踪卵母细胞到囊胚阶段，以评估这些改变的后果。换句话说，我们想要确定代谢相关的表观遗传修饰的分子特征，这些修饰是代代相传的。我们还发现线粒体功能是卵母细胞-胚胎质量的主要决定因素之一。我们的研究结果表明，配子体发生后期的大多数代谢应激导致第7天胚胎的线粒体功能障碍和质量差。因此，我们的第三个目标是使用β -氧化激活剂（如左卡尼汀）、衰减分子（如褪黑激素）或代谢抑制剂来调节和监测IVM期间的线粒体活性，以评估对线粒体基因表达和线粒体基因组DNA甲基化变化的影响。我们假设卵母细胞线粒体在囊胚阶段之前保持在“安静”模式，以防止自由基的形成，这种情况需要特定的代谢程序，这既影响胚胎的存活，也影响F-1代的未来代谢。这项研究肯定会对如何培养奶牛的卵母细胞和胚胎产生影响，以优化它们的生存和后代的健康。

This research program is exploring intergenerational programming through oocytes in the bovine species. For 3 decades, our laboratory has been involved in the understanding of the oocyte quality in bovine. Our recent discoveries indicate that the metabolic context perceived by the follicular cells surrounding the oocyte is a major determinant of the quality control process that ensures the production of a viable oocyte. We have also discovered that the information transmitted through the oocyte is not only important to produce a viable embryo but impacts the metabolic programming of the future individual. This epigenetic phenomenon is now emerging as a new paradigm in mammalian reproduction, and we have made substantial contribution to this field. We discovered that both mothers (cows) and fathers (bull) transmit information by the gametes to the embryos using non-genetic mechanisms (DNA methylation, micro-RNA and histones changes or retention). Our hypothesis is that the metabolic programming carried by the oocyte to the next generation relies on epigenetic mechanisms that are highly influenced by the follicular environment or in vitro culture conditions. To test this hypothesis, our first objective is to assess the impact of modulating energy metabolism modulators (lipids, sugars and metabolites) during in vitro maturation (IVM) of bovine oocytes and resulting blastocysts based on the post-partum cow's physiology. Considering the importance of the cumulus cells, our second objective is to investigate the acute response to metabolic stress in cumulus cells to understand how it may change the information and nutrients provided to the oocyte and then follow the oocyte to the blastocyst stage to assess the consequences of these modifications. In other words, we want to identify the molecular signature of metabolism-related epigenetic modifications that are transmitted across generations. We have also discovered that mitochondrial function is one of the major determinants of oocyte-embryo quality. Our results have shown that most metabolic stresses during late gametogenesis results in mitochondrial dysfunction in the day 7 embryo and poor quality. Therefore, our third objective is to modulate and monitor mitochondrial activity during IVM using activators of Beta-oxidation (e.g. L-carnitine), attenuation molecules (e.g. melatonin) or metabolic inhibitors to assess the effect on mitochondrial-gene expression and DNA methylation changes on the mitochondria genome. We postulate that the oocytes mitochondria are maintained in a `quiet' mode to prevent free radical formation until the blastocyst stage and that situation demands a specific metabolic programming which impacts both the embryo survival and the future metabolism of the F-1 generation. This research will certainly have an impact on how cow's oocytes and embryos are cultures to optimized their survival and the health of the offsprings.