Department of Reproductive Medicine, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
Department of Obstetrics and Gynaecology, British Columbia Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
Biol Reprod. 2022 Aug 9;107(2):458-473. doi: 10.1093/biolre/ioac070.
Hyaluronan is a structural component of the expanded cumulus matrix, and hyaluronan synthase 2 is the major enzyme for the synthesis of hyaluronan in humans. Versican cross-links the hyaluronan-rich matrix to cumulus cells and is critical for successful ovulation. Activin A is a critical intrafollicular regulator of ovarian function. Although activin A has been shown to promote cumulus matrix expansion in mice, the functional role of activin A in the regulation of cumulus expansion in the human ovary remains to be elucidated. Using primary and immortalized human granulosa-lutein cells as study models, we provide the first data showing that activin A increased the production of hyaluronan by upregulating the expression of hyaluronan synthase 2 in these cells. Additionally, activin A also promoted the expression of the hyaluronan-binding protein versican. Moreover, using inhibitor- and small interfering RNA-mediated inhibition approaches, we found that these stimulatory effects of activin A are most likely mediated through the type I receptor activin receptor-like kinase (ALK4)-mediated Sma- and Mad-related protein (SMAD2)/SMAD3-SMAD4 signaling pathway. Notably, the chromatin immunoprecipitation analyses demonstrated that SMAD4 could bind to human hyaluronan synthase 2 and VERSICAN promoters. The results obtained from this in vitro study suggest that locally produced activin A plays a functional role in the regulation of hyaluronan production and stabilization in human granulosa-lutein cells.
透明质酸是扩展的卵丘基质的结构成分，而透明质酸合酶 2 是人类合成透明质酸的主要酶。 蛋白聚糖通过将富含透明质酸的基质交联到卵丘细胞上，对于成功排卵至关重要。 激活素 A 是卵巢功能的重要卵泡内调节剂。 尽管已经表明激活素 A 可以促进小鼠卵丘基质的扩张，但激活素 A 在调节人类卵巢中卵丘扩张的功能作用仍有待阐明。 使用原代和永生化的人颗粒细胞-黄体细胞作为研究模型，我们提供了第一个数据，表明激活素 A 通过上调这些细胞中透明质酸合酶 2 的表达来增加透明质酸的产生。 此外，激活素 A 还促进了透明质酸结合蛋白蛋白聚糖的表达。 此外，使用抑制剂和小干扰 RNA 介导的抑制方法，我们发现激活素 A 的这些刺激作用很可能是通过 I 型受体激活素受体样激酶（ALK4）介导的 Sma 和 Mad 相关蛋白（SMAD2）/SMAD3-SMAD4 信号通路介导的。 值得注意的是，染色质免疫沉淀分析表明 SMAD4 可以结合人透明质酸合酶 2 和 VERSICAN 启动子。 这项体外研究的结果表明，局部产生的激活素 A 在调节人颗粒细胞-黄体细胞中透明质酸的产生和稳定中发挥功能作用。
