Oocyte-derived BMP15 but not GDF9 down-regulates connexin43 expression and decreases gap junction intercellular communication activity in immortalized human granulosa cells
Oocyte-derived BMP15 but not GDF9 down-regulates connexin43 expression and decreases gap junction intercellular communication activity in immortalized human granulosa cells
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DOI：
10.1093/molehr/gau001
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发表时间：
2014-05-01
影响因子：
4
通讯作者：
Leung, Peter C. K.
中科院分区：
文献类型：
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作者：
Chang, Hsun-Ming;Cheng, Jung-Chien;Leung, Peter C. K.
在卵巢中，颗粒细胞中的连接蛋白偶联间隙连接在卵泡和卵母细胞的发育以及黄体的形成中起着至关重要的作用。我们之前的研究表明，在永生化的人颗粒细胞中，膜细胞来源的骨形态发生蛋白（BMP）4和BMP7通过下调连接蛋白43 （Cx43）的表达来降低间隙连接细胞间通讯（GJIC）的活性。然而，卵母细胞来源的生长因子对Cx43表达的影响仍有待阐明。本研究旨在探讨卵母细胞衍生生长分化因子（GDF）9和BMP15对人颗粒细胞系SVOG中Cx43表达的影响。我们还研究了与GJIC活性相关的影响，并研究了潜在的作用机制。在SVOG细胞中，BMP15而不是GDF9处理显著降低Cx43 mRNA和蛋白水平以及GJIC活性。这些抑制作用，以及诱导Smad1/5/8磷酸化，通过与BMP I型受体抑制剂dorsomorphin共同处理而减弱。此外，使用小干扰RNA敲除转化生长因子- β超家族信号通路的中心成分Smad4，逆转了BMP15对Cx43表达和GJIC活性的抑制作用。BMP15对Cx43表达的抑制作用在体外受精的不孕症患者获得的原代人颗粒叶黄素细胞中得到进一步证实。这些发现表明，卵母细胞衍生的BMP15通过下调Cx43的表达来降低人颗粒细胞之间的GJIC活性，这很可能是通过smad依赖的信号通路。
In the ovary, connexin-coupled gap junctions in granulosa cells play crucial roles in follicular and oocyte development as well as in corpus luteum formation. Our previous work has shown that theca cell-derived bone morphogenetic protein (BMP)4 and BMP7 decrease gap junction intercellular communication (GJIC) activity via the down-regulation of connexin43 (Cx43) expression in immortalized human granulosa cells. However, the effects of oocyte-derived growth factors on Cx43 expression remain to be elucidated. The present study was designed to investigate the effects of oocyte-derived growth differentiation factor (GDF)9 and BMP15 on the expression of Cx43 in a human granulosa cell line, SVOG. We also examined the effect relative to GJIC activity and investigated the potential mechanisms of action. In SVOG cells, treatment with BMP15 but not GDF9 significantly decreased Cx43 mRNA and protein levels and GJIC activity. These suppressive effects, along with the induction of Smad1/5/8 phosphorylation, were attenuated by co-treatment with a BMP type I receptor inhibitor, dorsomorphin. Furthermore, knockdown of the central component of the transforming growth factor-beta superfamily signaling pathway, Smad4, using small interfering RNA reversed the suppressive effects of BMP15 on Cx43 expression and GJIC activity. The suppressive effects of BMP15 on Cx43 expression were further confirmed in primary human granulosa-lutein cells obtained from infertile patients undergoing an in vitro fertilization procedure. These findings suggest that oocyte-derived BMP15 decreases GJIC activity between human granulosa cells by down-regulating Cx43 expression, most likely via a Smad-dependent signaling pathway.