Nilsson Eric E, Skinner Michael K
Center for Reproductive Biology, School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4231, USA.
Biol Reprod. 2003 Oct;69(4):1265-72. doi: 10.1095/biolreprod.103.018671. Epub 2003 Jun 11.
The growth and development of follicles within the ovary are highly dependent on autocrine and paracrine signaling involving growth factors from granulosa cells, theca cells, stromal interstitial cells, and the oocytes. The growth factor bone morphogenetic protein-4 (BMP-4) and its receptor (BMPR-IB) have been detected in ovaries, and a mutation in BMPR-IB has been associated with abnormal ovulation rate. The objective of the current study was to examine the role that BMP-4 plays in the early stages of primordial follicle development. Ovaries from 4-day-old rats were placed into a whole-ovary organ culture system for 2 wk to investigate the effect that treatment with exogenous BMP-4 has on early follicle development. BMP-4-treated ovaries had a significantly higher proportion of developing primary follicles and fewer arrested primordial follicles than did untreated controls. This indicates that BMP-4 promotes primordial follicle development and the primordial-to-primary follicle transition. Ovaries were also treated with neutralizing antibody against BMP-4 to determine effects of removing endogenously produced BMP-4. Interestingly, ovaries treated with BMP-4 antibody were markedly smaller than controls. This was associated with a progressive loss of oocytes and primordial follicles, a progressive increase in cellular apoptosis, and an accompanying loss of normal ovarian tissue morphology over time. Immunocytochemistry localized BMP-4 protein to isolated stromal cell populations, selected stromal cells (i.e., pretheca cells) associated with developing primordial follicles, and the basement membrane of follicles. Ovaries were treated with BMP-4 and RNA collected after organ culture to determine whether BMP-4 signaling affects expression of other growth factors. Kit ligand and basic fibroblast growth factor expression was unchanged, but TGFalpha expression was decreased in whole ovaries. Taken together, these data suggest that BMP-4 plays an important role in promoting the survival and development of primordial follicles in the neonatal ovary.
卵巢内卵泡的生长和发育高度依赖于自分泌和旁分泌信号传导，这些信号传导涉及来自颗粒细胞、卵泡膜细胞、基质间质细胞和卵母细胞的生长因子。生长因子骨形态发生蛋白-4（BMP-4）及其受体（BMPR-IB）已在卵巢中被检测到，并且BMPR-IB中的突变与排卵率异常有关。本研究的目的是研究BMP-4在原始卵泡发育早期所起的作用。将4日龄大鼠的卵巢置于全卵巢器官培养系统中培养2周，以研究外源性BMP-4处理对早期卵泡发育的影响。与未处理的对照组相比，经BMP-4处理的卵巢中正在发育的初级卵泡比例显著更高，而停滞的原始卵泡更少。这表明BMP-4促进原始卵泡发育以及原始卵泡向初级卵泡的转变。还用抗BMP-4的中和抗体处理卵巢，以确定去除内源性产生的BMP-4的效果。有趣的是，用BMP-4抗体处理的卵巢明显小于对照组。这与卵母细胞和原始卵泡的逐渐丧失、细胞凋亡的逐渐增加以及随着时间的推移正常卵巢组织形态的丧失有关。免疫细胞化学将BMP-4蛋白定位到分离的基质细胞群体、与正在发育的原始卵泡相关的选定基质细胞（即前卵泡膜细胞）以及卵泡的基底膜。在器官培养后，用BMP-4处理卵巢并收集RNA，以确定BMP-4信号传导是否影响其他生长因子的表达。Kit配体和碱性成纤维细胞生长因子的表达未发生变化，但整个卵巢中TGFα的表达降低。综上所述，这些数据表明BMP-4在促进新生卵巢中原始卵泡的存活和发育方面发挥着重要作用。
