Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, People's Republic of China.
The China Conservation and Research Center for the Giant Panda, Wolong, People's Republic of China.
Sci Rep. 2021 Feb 25;11(1):4683. doi: 10.1038/s41598-021-84140-w.
Within the oocytes of chicken preovulatory follicles, the engulfed yolk constitutes 99% of the oocyte content, while the small germinal disc (GD) (which contains the nucleus and 99% ooplasm) occupies only less than 1%. Relative to the position of the GD, the single granulosa cell layer surrounding the oocyte can be sub-divided into two sub-populations: granulosa cells proximal (named Gp cells) and distal (Gd cells) to the GD. It was reported that Gp cells and Gd cells differ in their morphology, proliferative rate and steroidogenic capacity, however, the underlying mechanism controlling granulosa cell heterogeneity remains unclear. Here we analyzed the transcriptomes of Gd and Gp cells of preovulatory (F5 and F1) follicles in chicken ovaries. We found that: (1) genes associated with cell cycle and DNA replication (CDK1, CCNB3 etc.) have comparatively higher expression levels in Gp cells than in Gd cells, while genes associated with steroidogenesis (CYP51A1, DHCR24) are highly expressed in Gd cells, indicating that Gp cells are likely more mitotic and less steroidogenic than Gd cells; (2) genes associated with extracellular matrix remodeling, cell adhesion and sperm binding (ZP3, ZP2) are differentially expressed in Gp and Gd cells; (3) Furthermore, signaling molecules (WNT4/IHH) and receptors for NGF (NGFR), epidermal growth factor (EGFR), gonadotropins (FSHR/LHR) and prostaglandin (PTGER3) are abundantly but differentially expressed in Gp and Gd cells. Taken together, our data strongly supports the notion that Gp and Gd cells of preovulatory follicles differ in their proliferation rate, steroidogenic activity, ECM organization and sperm binding capacity, which are likely controlled by gonadotropins and local ovarian factors, such as GD-derived factors.
在鸡排卵前卵泡的卵母细胞中，被吞噬的卵黄构成卵母细胞内容物的 99%，而小的生殖盘（GD）（包含核和 99%的卵质）仅占不到 1%。相对于 GD 的位置，围绕卵母细胞的单层颗粒细胞层可分为两个亚群：靠近 GD 的颗粒细胞（称为 Gp 细胞）和远离 GD 的颗粒细胞（Gd 细胞）。据报道，Gp 细胞和 Gd 细胞在形态、增殖率和类固醇生成能力上存在差异，但控制颗粒细胞异质性的潜在机制尚不清楚。在这里，我们分析了鸡卵巢排卵前（F5 和 F1）卵泡的 Gd 和 Gp 细胞的转录组。我们发现：（1）与细胞周期和 DNA 复制相关的基因（CDK1、CCNB3 等）在 Gp 细胞中的表达水平高于 Gd 细胞，而与类固醇生成相关的基因（CYP51A1、DHCR24）在 Gd 细胞中高度表达，这表明 Gp 细胞比 Gd 细胞更有丝分裂，类固醇生成能力更低；（2）与细胞外基质重塑、细胞黏附和精子结合相关的基因（ZP3、ZP2）在 Gp 和 Gd 细胞中表达不同；（3）此外，信号分子（WNT4/IHH）和神经生长因子（NGF）受体（NGFR）、表皮生长因子（EGF）受体（EGFR）、促性腺激素（FSHR/LHR）和前列腺素（PTGER3）在 Gp 和 Gd 细胞中大量但表达不同。总之，我们的数据强烈支持这样一种观点，即排卵前卵泡的 Gp 和 Gd 细胞在增殖率、类固醇生成活性、细胞外基质组织和精子结合能力上存在差异，这些差异可能受促性腺激素和局部卵巢因子（如 GD 衍生因子）的控制。
