Qi Xin, Salem Mohamed, Zhou Wenyi, Sato-Shimizu Miwa, Ye Gang, Smitz Johan, Peng Chun
Department of Biology (X.Q., M.S., W.Z., G.Y., C.P.), York University, Toronto, Ontario, Canada M3J 1P3; and Follicle Biology Laboratory (M.S.S., J.S.), Free University of Brussels Vrije Universiteit Brussel, 1090 Brussel, Belgium.
Endocrinology. 2016 Sep;157(9):3355-65. doi: 10.1210/en.2016-1354. Epub 2016 Jul 26.
Neurokinin B (NKB) and its receptor, NK3R, play critical roles in reproduction by regulating the secretion of the hypothalamic GnRH. NKB and NK3R genes are also expressed in the ovary; however, their physiological roles within the ovary are unknown. The aim of this study was to determine whether NKB acts directly on the ovary to regulate reproduction. Injection of NKB into zebrafish accelerated follicle development, increased the mRNA levels of cyp11a1 and cyp19a1, and enhanced estradiol production. Similarly, NKB induced cyp11a1 and cyp19a1 expression in primary cultures of zebrafish follicular cells and stimulated estradiol production from cultured follicles. Furthermore, NKB activates cAMP response element-binding protein and ERK, and ERK inhibitors abolished the effect of NKB on cyp11a1, whereas protein kinase A and calmodulin-dependent protein kinase II inhibitors that blocked the activation of cAMP response element-binding protein, attenuated the effect of NKB on cyp19a1 expression. In a human granulosa cell line, COV434, a NKB agonist, senktide, also increased CYP11A1 and CYP19A1 mRNA levels and enhanced aromatase protein levels and activities. Small interfering RNA-mediated knockdown of NK3R reduced senktide-induced CYP11A1 and CYP19A1 mRNA levels. Finally, we found that NK3R mRNA was strongly down-regulated in granulosa cells obtained from polycystic ovary syndrome (PCOS) patients when compared with non-PCOS subjects. Taken together, our findings establish a direct action of NKB to induce ovarian estrogen production and raise the possibility that defective signaling of this pathway may contribute to the development of PCOS.
神经激肽B（NKB）及其受体NK3R通过调节下丘脑促性腺激素释放激素（GnRH）的分泌在生殖过程中发挥关键作用。NKB和NK3R基因也在卵巢中表达；然而，它们在卵巢内的生理作用尚不清楚。本研究的目的是确定NKB是否直接作用于卵巢来调节生殖。向斑马鱼注射NKB可加速卵泡发育，增加cyp11a1和cyp19a1的mRNA水平，并提高雌二醇的产生。同样，NKB在斑马鱼卵泡细胞原代培养物中诱导cyp11a1和cyp19a1表达，并刺激培养卵泡产生雌二醇。此外，NKB激活环磷酸腺苷反应元件结合蛋白（cAMP response element-binding protein，CREB）和细胞外信号调节激酶（ERK），ERK抑制剂消除了NKB对cyp11a1的作用，而阻断CREB激活的蛋白激酶A和钙调蛋白依赖性蛋白激酶II抑制剂减弱了NKB对cyp19a1表达的作用。在人颗粒细胞系COV434中，NKB激动剂森克肽（senktide）也增加了CYP11A1和CYP19A1的mRNA水平，并提高了芳香化酶蛋白水平和活性。小干扰RNA介导的NK3R敲低降低了森克肽诱导的CYP11A1和CYP19A1 mRNA水平。最后，我们发现与非多囊卵巢综合征（PCOS）患者相比，从PCOS患者获得的颗粒细胞中NK3R mRNA强烈下调。综上所述，我们的研究结果证实了NKB诱导卵巢雌激素产生的直接作用，并提出该信号通路缺陷可能导致PCOS发生的可能性。
