Elucidation of the physiological roles of Hippo signalling in bovine ovarian follicle cells

河马是一个进化上保守的信号通路，在胚胎发育过程中对多种组织的细胞分化、增殖和凋亡具有既定的作用。河马核心通路由一条对转录激活因子是相关蛋白(YAP)和带有PDZ结合基序的转录辅助激活因子(TAZ)进行负调控的激酶级联反应组成。虽然最近在人类和啮齿动物身上的研究已经将河马信号与女性的原发性卵巢功能不全联系起来，但还没有研究表明河马信号在具有农业重要性的物种(如牛)的卵巢生理和/或病理生理学中的作用。因此，我们将在牛卵巢卵泡中研究这一途径。*我们的初步结果表明，在牛排卵前颗粒细胞中，关键的河马信号效应因子YAP/TAZ受黄体生成素(LH)的调节。因此，我们推测，黄体生成素激活了牛颗粒细胞中的河马信号，它需要YAP和TAZ在黄体化、卵丘细胞-卵母细胞复合体扩张和排卵中发挥作用。为了证实这一点，我们将使用体外和体内的牛模型。还需要进行实验，以确定促卵泡激素(FSH)是否调节河马效应分子在牛颗粒细胞中的表达和活性，目的是什么，以及这是否与牛卵泡的生长有关。*我的研究计划的主要重点是确定关键的河马信号效应因子在奶牛卵泡发育过程中的相关性。这项建议的短期目标是：1)阐明河马信号通路在排卵级联中的作用；2)阐明河马信号效应因子在卵泡发育中的作用；3)确定河马在牛颗粒细胞中的作用机制。*这项在牛身上的研究将首次为该物种卵泡生长和排卵过程中一条全新的信号通路的调节、生理作用和作用机制提供相当深入的认识。这些发现可能会导致在体内操纵河马信号的应用，例如针对特定信号通路效应器的药理学靶向，这可能导致行业资金更好地利用高遗传优势动物的卵巢卵泡储备，进行体外胚胎生产。这是加拿大乳制品行业的一项主要经济活动，2016年有超过1.2万个胚胎出口到30多个国家，创造了超过800万美元的贸易额。

Hippo is an evolutionarily conserved signaling pathway with established roles in cell differentiation, proliferation and apoptosis in a variety of tissues during embryogenesis. The core Hippo pathway consists of a kinase cascade that negatively regulates the activity of the transcriptional activators yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ). Although recent studies in humans and rodents have linked the Hippo signaling to primary ovarian insufficiency in women, there are no studies showing the roles of Hippo signaling in ovarian physiology and/or pathophysiology of species of agricultural importance, as the cow. Therefore, we will investigate this pathway in the bovine ovarian follicle.*** Our preliminary results indicated that key Hippo signaling effectors, YAP/TAZ, are regulated by the luteinizing hormone (LH) in bovine preovulatory granulosa cells. We, therefore, hypothesized that LH activates Hippo signaling in bovine granulosa cells and that it requires YAP and TAZ to exert its effects on luteinization, cumulus cell-oocyte complex expansion and ovulation. To confirm this, we will use in vitro and in vivo bovine models. Experiments will be also required to determine if follicle-stimulating hormone (FSH) modulates Hippo effectors expression and activity in bovine granulosa cells, for what purpose and if this is relevant to bovine follicle growth. *** The main focus for my research program is to determine the relevance of key Hippo signaling effectors throughout follicle development in cows. The short-term objectives of this proposal are 1) to elucidate the involvement of Hippo signaling in the ovulatory cascade, 2) to elucidate the involvement of Hippo signaling effectors in follicle development, and 3) to determine the mechanisms of Hippo action in bovine granulosa cells.*** Together, the proposed studies in cattle will provide, for the first time, considerable insight into the regulation, physiological roles and mechanisms of action of a completely novel signaling pathway during ovarian follicle growth and ovulation in this species. These findings may lead to applications for the manipulation of Hippo signaling in vivo, such as the pharmacological targeting of specific signaling pathway effectors, that may result in industry funding to better use the ovarian follicle reserve in high genetic merit animals superovulated for in vitro embryo production. This is a major economic activity in the Canadian dairy industry with over 12,000 embryos being exported to over 30 countries in 2016, creating trade worth more than $8 million.