Matsui Motozumi, Sonntag Barbara, Hwang Seong Soo, Byerly Tara, Hourvitz Ariel, Adashi Eli Y, Shimasaki Shunichi, Erickson Gregory F
Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093-0674, USA.
Endocrinology. 2004 Aug;145(8):3686-95. doi: 10.1210/en.2003-1642. Epub 2004 Apr 15.
Pregnancy-associated plasma protein-A (PAPP-A) is the major IGF binding protein-4 (IGFBP-4) protease in follicular fluid, consistent with its proposed role in folliculogenesis. Despite growing interest, almost nothing is known about how PAPP-A expression is regulated in any tissue. Here we show that FSH and oocytes regulate PAPP-A expression in granulosa cells (GCs). By in situ hybridization, ovary PAPP-A mRNA was markedly increased by pregnant mare serum gonadotropin treatment, and the message was localized to the membrana GCs but not cumulus GCs (CGCs) of dominant follicles. To explore the mechanism, we used primary cultures of rat GCs. Control (untreated) cells produced little or no PAPP-A spontaneously. Conversely, FSH markedly stimulated PAPP-A mRNA and protein in a dose- and time-dependent fashion. Interestingly, PAPP-A expression in isolated CGCs was also strongly induced by FSH, and the induction was inhibited by added oocytes. To investigate the nature of the inhibition, we tested the effect of oocyte-derived bone morphogenetic protein-15 (BMP-15). BMP-15 alone had no effect on basal levels of PAPP-A expression by cultures of membrana GCs or CGCs. However, BMP-15 markedly inhibited the FSH stimulation of PAPP-A production in a dose-dependent manner. The cleavage of IGFBP-4 by conditioned media from FSH-treated GCs was completely inhibited by anti-PAPP-A antibody, indicating the IGFBP-4 protease secreted by GCs is PAPP-A. These results demonstrate stimulatory and inhibitory roles for FSH and BMP-15, respectively, in regulating PAPP-A production by GCs. We propose that FSH and oocyte-derived BMP-15 form a controlling network that ensures the spatiotemporal pattern of GC PAPP-A expression in the dominant follicle.
妊娠相关血浆蛋白-A（PAPP-A）是卵泡液中主要的胰岛素样生长因子结合蛋白-4（IGFBP-4）蛋白酶，与其在卵泡发生中的假定作用一致。尽管人们对此的兴趣日益浓厚，但对于PAPP-A在任何组织中的表达调控方式几乎一无所知。在此，我们表明促卵泡激素（FSH）和卵母细胞可调节颗粒细胞（GCs）中PAPP-A的表达。通过原位杂交，孕马血清促性腺激素处理可使卵巢PAPP-A mRNA显著增加，且该信息定位于优势卵泡的膜颗粒细胞而非卵丘颗粒细胞（CGCs）。为探究其机制，我们使用了大鼠颗粒细胞的原代培养物。对照（未处理）细胞几乎不自发产生PAPP-A。相反，FSH以剂量和时间依赖性方式显著刺激PAPP-A mRNA和蛋白的表达。有趣的是，FSH也强烈诱导分离的CGCs中PAPP-A的表达，而添加卵母细胞可抑制这种诱导作用。为研究这种抑制的本质，我们测试了卵母细胞衍生的骨形态发生蛋白-15（BMP-15）的作用。单独的BMP-15对膜颗粒细胞或CGCs培养物中PAPP-A表达的基础水平无影响。然而，BMP-15以剂量依赖性方式显著抑制FSH对PAPP-A产生的刺激作用。来自FSH处理的颗粒细胞的条件培养基对IGFBP-4的切割被抗PAPP-A抗体完全抑制，表明颗粒细胞分泌的IGFBP-4蛋白酶是PAPP-A。这些结果分别证明了FSH和BMP-15在调节颗粒细胞产生PAPP-A中的刺激和抑制作用。我们提出，FSH和卵母细胞衍生的BMP-15形成一个控制网络，确保优势卵泡中颗粒细胞PAPP-A表达的时空模式。
