Paracrine actions of growth differentiation factor-9 in the mammalian ovary.
Paracrine actions of growth differentiation factor-9 in the mammalian ovary.
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DOI：
10.1210/mend.13.6.0310
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发表时间：
1999-06
影响因子：
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通讯作者：
Julia A. Elvin;Amander T. Clark;Pei Wang;N. Wolfman;M. Matzuk
中科院分区：
文献类型：
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作者：
Julia A. Elvin;Amander T. Clark;Pei Wang;N. Wolfman;M. Matzuk
虽然转化生长因子- β (tgf - β)超家族是最大的分泌生长因子家族，但令人惊讶的是，在其信号通路中发现的下游靶基因很少。同样，调节卵母细胞与体细胞相互作用的卵母细胞衍生分泌因子的身份在很大程度上仍然未知。例如，已知卵母细胞分泌旁分泌生长因子(s)，这是积云扩张、诱导透明质酸合成和抑制LH受体（LHR） mRNA合成所必需的。我们之前的研究表明，tgf - β家族成员生长分化因子-9 （GDF-9）的缺失会在原发性卵泡期阻碍卵巢卵泡发生，导致不孕。在本研究中，我们证明小鼠GDF-9蛋白在3a型卵泡期开始的所有卵母细胞中表达，包括窦卵泡。为了探索GDF-9在卵泡发生和积云扩增后期的生物学功能，我们利用中国仓鼠卵巢细胞表达系统制备了成熟的、糖基化的重组小鼠GDF-9。建立颗粒细胞培养系统，利用半定量RT-PCR技术确定GDF-9在调节卵巢几个关键基因产物中的作用。我们发现重组GDF-9诱导透明质酸合成酶2 （HAS2）、环氧化酶2 （COX-2）和类固醇急性调节蛋白（StAR） mRNA的合成，但抑制尿激酶纤溶酶原激活物（uPA）和LHR mRNA的合成。与GDF-9诱导StAR mRNA一致，重组GDF-9在缺乏FSH的情况下增加颗粒细胞孕酮的合成。由于在积云细胞中诱导HAS2和抑制蛋白酶uPA是在积云扩张过程中产生富含透明质酸的细胞外基质的关键事件，我们确定了GDF-9是否可以模拟这一过程。利用卵母细胞切除的积云细胞-卵母细胞复合物，我们发现重组GDF-9在体外诱导积云扩增。这些研究表明GDF-9可以与颗粒细胞上的受体结合，调节多种基因产物的表达。因此，GDF-9除了在卵泡早期形成过程中作为生长和分化因子发挥关键作用外，还作为卵母细胞分泌的旁分泌因子，调节几种关键颗粒细胞酶，这些酶参与卵丘扩张和维持最佳卵母细胞微环境，这些过程对正常排卵、受精和女性生殖至关重要。
Although the transforming growth factor-beta (TGF-beta) superfamily is the largest family of secreted growth factors, surprisingly few downstream target genes in their signaling pathways have been identified. Likewise, the identities of oocyte-derived secreted factors, which regulate important oocyte-somatic cell interactions, remain largely unknown. For example, oocytes are known to secrete paracrine growth factor(s) which are necessary for cumulus expansion, induction of hyaluronic acid synthesis, and suppression of LH receptor (LHR) mRNA synthesis. Our previous studies demonstrated that absence of the TGF-beta family member, growth differentiation factor-9 (GDF-9), blocks ovarian folliculogenesis at the primary follicle stage leading to infertility. In the present study, we demonstrate that mouse GDF-9 protein is expressed in all oocytes beginning at the type 3a follicle stage including antral follicles. To explore the biological functions of GDF-9 in the later stages of folliculogenesis and cumulus expansion, we produced mature, glycosylated, recombinant mouse GDF-9 using a Chinese hamster ovary cell expression system. A granulosa cell culture system was established to determine the role of GDF-9 in the regulation of several key ovarian gene products using semiquantitative RT-PCR. We find that recombinant GDF-9 induces hyaluronan synthase 2 (HAS2), cyclooxygenase 2 (COX-2), and steroidogenic acute regulator protein (StAR) mRNA synthesis but suppresses urokinase plasminogen activator (uPA) and LHR mRNA synthesis. Consistent with the induction of StAR mRNA by GDF-9, recombinant GDF-9 increases granulosa cell progesterone synthesis in the absence of FSH. Since induction of HAS2 and suppression of the protease uPA in cumulus cells are key events in the production of the hyaluronic acid-rich extracellular matrix which is produced during cumulus expansion, we determined whether GDF-9 could mimic this process. Using oocytectomized cumulus cell-oocyte complexes, we show that recombinant GDF-9 induces cumulus expansion in vitro. These studies demonstrate that GDF-9 can bind to receptors on granulosa cells to regulate the expression of a number of gene products. Thus, in addition to playing a critical function as a growth and differentiation factor during early folliculogenesis, GDF-9 functions as an oocyte-secreted paracrine factor to regulate several key granulosa cell enzymes involved in cumulus expansion and maintenance of an optimal oocyte microenvironment, processes which are essential for normal ovulation, fertilization, and female reproduction.