Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Endocrinology. 2010 Apr;151(4):1914-22. doi: 10.1210/en.2009-0767. Epub 2010 Feb 22.
The pattern and regulation of endothlin-2 (EDN2) expression and its putative roles in bovine ovaries were investigated. EDN2 mRNA was determined in corpus luteum (CL) and during folliculoluteal transition induced by GnRH in vivo. EDN2 was elevated only in the early CL and was not present in older CL. In the young CL, EDN2 mRNA was identified mainly in luteal cells but not endothelial cells that expressed the EDN1 gene. Similarly, in preovulatory follicles, EDN2 was expressed in the granulosa cells (GCs) and not in the vascular theca interna. LH and hypoxia are two major stimulants of CL formation. Therefore, GCs were cultured with bovine LH, under hypoxic conditions. GCs incubated with bovine LH resulted in increased EDN2 mRNA 42 h later. CoCl2, a hypoxia-mimicking agent, elevated EDN2 in GCs in a dose-dependent manner. Incubation of the human GC line (Simian virus 40 large T antigen) under low oxygen tension (1%) augmented EDN2 6 and 24 h later. In these two cell types, along with EDN2, hypoxia augmented VEGF. EDN2 induced in GCs changes that characterize the developing CL: cell proliferation as well as up-regulation of vascular endothelial growth factor and cyclooxygenase-2 (mRNA and protein levels). Human chorionic gonadotropin also up-regulated these two genes. Small interfering RNA targeting EDN-converting enzyme-1 effectively reduced its mRNA levels. This treatment, expected to lower the mature EDN2 peptide production, inhibited VEGF mRNA levels and GC numbers. Together these data suggest that elevated EDN2 in the early bovine CL, triggered by LH surge and hypoxia, may facilitate CL formation by promoting angiogenesis, cell proliferation, and differentiation.
研究了内皮素-2（EDN2）表达的模式和规律及其在牛卵巢中的潜在作用。通过体内 GnRH 诱导的黄体和卵泡黄体转化，确定了 corpus luteum (CL) 和 EDN2 mRNA。EDN2 仅在早期 CL 中升高，在较老的 CL 中不存在。在年轻的 CL 中，EDN2 mRNA 主要在黄体细胞中鉴定，但不在表达 EDN1 基因的内皮细胞中。同样，在排卵前卵泡中，EDN2 在颗粒细胞（GC）中表达，而不在血管内膜中表达。LH 和缺氧是 CL 形成的两个主要刺激因素。因此，将 GC 与牛 LH 在缺氧条件下培养。用牛 LH 孵育的 GC 导致 42 小时后 EDN2 mRNA 增加。缺氧模拟剂 CoCl2 以剂量依赖的方式升高 GC 中的 EDN2。在低氧张力（1%）下孵育人 GC 系（Simian virus 40 large T antigen），6 小时和 24 小时后 EDN2 增加。在这两种细胞类型中，与 EDN2 一起，缺氧会增加 VEGF。EDN2 在 GC 中诱导的变化可表征正在发育的 CL：细胞增殖以及血管内皮生长因子和环氧化酶-2（mRNA 和蛋白质水平）的上调。人绒毛膜促性腺激素也上调了这两个基因。靶向 EDN 转化酶-1 的小干扰 RNA 有效降低了其 mRNA 水平。这种治疗方法预计会降低成熟 EDN2 肽的产生，抑制 VEGF mRNA 水平和 GC 数量。这些数据表明，LH 激增和缺氧引起的早期牛 CL 中 EDN2 的升高，可能通过促进血管生成、细胞增殖和分化来促进 CL 的形成。
