Interplay between paracrine signaling and gap junctional communication in ovarian follicles
Interplay between paracrine signaling and gap junctional communication in ovarian follicles
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DOI：
10.1242/jcs.01587
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发表时间：
2005-01-01
影响因子：
4
通讯作者：
Kidder, GM
中科院分区：
文献类型：
--
作者：
Gittens, JEI;Barr, KJ;Kidder, GM
细胞间通讯是卵巢卵泡发生所必需的。这在缺乏连接蛋白43 （Cx43，一种在颗粒细胞中强烈表达的间隙连接蛋白）、生长/分化因子9 （GDF9，一种刺激颗粒细胞增殖和分化的卵母细胞特异性生长因子）或表达Kit配体突变形式（KITL，一种在卵巢中由颗粒细胞分泌以刺激卵母细胞生长的旁分泌因子）的小鼠中表现得很明显。在所有这些突变系中，卵泡生长受损，表明旁分泌信号和间隙连接通信之间可能存在相互作用。为了评估这种可能性，我们分析了突变卵巢中的基因表达。尽管Cx43零突变卵巢颗粒细胞之间缺乏间隙连接偶联，但编码KITL及其受体KIT的基因表达得以维持。此外，GDF9的表达得以维持。在GDF9零突变卵巢中，Cx43的表达没有明显变化，相应地，颗粒细胞保持偶联。在缺乏Cx43或GDF9的卵巢中，颗粒细胞凋亡也没有增加。增殖细胞核抗原（PCNA）染色显示Cx43零突变子房颗粒细胞DNA合成频率降低。通过放射性胸苷结合和体外PCNA染色，我们发现重组GDF9可以使偶联缺陷颗粒细胞的增殖恢复到对照细胞的水平。这些结果表明，在缺乏Cx43的小鼠中，卵泡发生受损至少部分是由于颗粒细胞对卵母细胞衍生的GDF9的反应性降低，表明这两种细胞间通讯模式之间存在相互作用。
Intercellular communication is required for ovarian folliculogenesis. This is apparent in mice lacking connexin43 (Cx43, a gap junction protein strongly expressed in granulosa cells), or growth/differentiation factor-9 (GDF9, an oocyte-specific growth factor that stimulates granulosa cell proliferation and differentiation), or in mice expressing a mutant form of Kit ligand (KITL, a paracrine factor that, in the ovary, is secreted by granulosa cells to stimulate oocyte growth). In all of these mutant lines, follicle growth is impaired suggesting a possible interaction between paracrine signaling and gap junctional communication. To assess this possibility, we analyzed gene expression in mutant ovaries. Despite the lack of gap junctional coupling between granulosa cells of Cx43 null mutant ovaries, expression of the genes encoding KITL and its receptor, KIT, is maintained. Furthermore, GDF9 expression is maintained. In GDF9 null mutant ovaries, there is no apparent change in Cx43 expression and, correspondingly, the granulosa cells remain coupled. There is also no increase in granulosa cell apoptosis in ovaries lacking Cx43 or GDF9. Staining for proliferating cell nuclear antigen (PCNA) revealed that the granulosa cells of Cx43 null mutant ovaries have a reduced frequency of DNA synthesis. Using both radiolabeled thymidine incorporation and PCNA staining in vitro, we showed that recombinant GDF9 could restore the proliferation of coupling-deficient granulosa cells to the level of control cells. These results indicate that impaired folliculogenesis in mice lacking Cx43 is due at least in part to reduced responsiveness of granulosa cells to oocyte-derived GDF9, indicating an interaction between these two modes of intercellular communication.