【作者】 王勇；

【导师】 孙斐；

【作者基本信息】 中国科学技术大学 ， 遗传学， 2013， 博士

【摘要】 TrkA是神经营养因子(NGF)高亲和力的受体,而NGF是神经营养因子家族中的一员,TrkA被认为在卵巢卵泡发育过程成起重要作用,例如其参与原始卵泡的装配,也能促进早期卵泡的发育,还能诱导次级卵泡的分化,还能够促进卵母细胞的排出。然后,关于TrkA在卵丘卵母细胞复合物(COCs)扩展过程中所起的作用还不清楚。在本研究中,我们发现TrkA在大的有腔卵泡中表达丰富,所以TrkA可能在卵泡发育的后期发挥作用,其中就包括COCs的扩展。在卵丘颗粒细胞中沉默TrkA会抑制表皮生长因子(EGF)诱导的COCs的扩展,而且还降低了卵母细胞排出的比率。所以TrkA参与EGF诱导的卵丘细胞的扩展是很明确的。‘TrkA在COCs扩展过程中所起的作用不是通过EGF的下游分子ERK1/2或SMAD的磷酸化来实现的,也不是通过上调COCs扩展相关基因,例如前列腺素内过氧化物合酶2(Ptgs2),透明质酸合成酶2(Has2),肿瘤坏死因子诱导蛋白6(Tnfaipd),以及pentraxin3(Ptx3)来实现的。因此在这个过程中可能存在一个新的COCs扩展相关基因。然而,用K252a对TrkA进行药物阻断,抑制其信号转导活性,可以导致卵丘颗粒细胞内白细胞介素6(IL-6)的mRNA表达和蛋白分泌水平的下降,而IL-6是通过我们对COCs进行K252a预处理,然后进行mRNA微阵列分析而筛选出来的。此外,IL-6还可以恢复K252a对EGF诱导的卵丘颗粒细胞扩展的抑制效应,也恢复了K252a对卵母细胞排出的抑制效应。而且,COCs扩展相关基因和IL-6一样,在卵丘颗粒细胞中还是炎症相关基因。因此,IL-6可能作为一个新的潜在的卵丘颗粒细胞扩展相关基因,也可能涉及到TrkA信号通路和EGF信号通路在影响COCs扩展方面的交汇。在本研究中,我们对TrkA在EGF诱导的卵丘颗粒细胞扩展过程中的作用提供了一个机制方面的见解。理解TrkA和EGF影响卵丘颗粒细胞扩展潜在性的交叉点,有助于我们发现一些排卵相关疾病的新的治疗靶点。更多还原

【Abstract】 TrkA, the high-affinity receptor of nerve growth factor (NGF), one of NTs family, is known to play key roles in ovarian follicular development, such as on assembling primordial follicles, promoting the early stages of follicular development, inducing the initial biochemical differentiation of secondary follicles into gonadotropin-responsive structures and facilitating ovulation. However, little is known about the roles of TrkA in cumulus oocyte complex (COCs) expansion.In this study, we found that TrkA was abundant in large antral follicles, so TrkA may play a role in the late stage of follicular development, such as cumulus expansion. Knockdown of TrkA in cumulus cells attenuated epidermal growth factor (EGF)-induced COCs expansion and further decreased the ovulation rate. So it is clear that TrkA participate in EGF-induced cumulus expansion. The effect of TrkA on COCs expansion was not mediated through downstream EGF effectors, phosphorylation of ERK1/2or SMAD, or through up-regulation of COCs expansion-related transcripts such as prostaglandin-endoperoxide synthase2(Ptgs2), hyaluronan synthase2(Has2), TNF-induced protein6(Tnfaip6) or pentraxin3(Ptx3). So there may be a new COCs expansion-related transcripts during this process. However, pharmacological blockade of TrkA transducing activity (K252a) in COCs decreased them RNA expression and protein secretion of interleukin-6(IL-6) in cumulus, identified from mRNA microarray of K252a-treated COCs. In addition, IL-6rescued the inhibitory effect of K252a on EGF-induced cumulus expansion, and on ovlation ratio. Furthermore, COCs expansion-related transcripts, as well as IL-6, also serve as inflammation-related genes in cumulus cells. Therefore, IL-6may act as a new potential cumulus expansion-related transcript, which may be involved in the integration of TrkA and EGF signaling in affecting COCs expansion. Here, we provide mechanistic insights into the roles of TrkA in EGF-induced cumulus expansion. Understanding potential cross-points between TrkA and EGF affecting cumulus expansion will help in the discovery of new therapeutic targets in ovulation-related diseases.更多还原