School of Basic Medical Sciences, Zunyi Medical University, Zunyi, China, 563000.
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China, 100101.
Biol Reprod. 2020 Jun 23;103(1):60-69. doi: 10.1093/biolre/ioaa042.
Wt1 gene encodes a nuclear transcription factor which is specifically expressed in ovarian granulosa cells and testicular Sertoli cells. Our previous studies demonstrated that Wt1 is required for the lineage specification of supporting cells and inactivation of Wt1 results in Sertoli cells to Leydig-like cells transformation. To test whether Wt1 is also involved in lineage maintenance of granulosa cells during ovary development, Wt1 was specifically deleted in pre-granulosa cells using Foxl2-cre. We found that the female Wt1-/flox; Foxl2-cre mice were infertile with atrophic ovaries and no growing follicles with multiple layers of granulosa cells were observed. A large number of 3β-HSD-positive steroidogenic cells were detected in ovaries of Wt1-/flox; Foxl2-cre mice during embryonic stage and these cells were derived from Foxl2-expressing pre-granulosa cells. The quantitative results showed the expression of granulosa cell marker genes (Foxl2, Follistatin) was downregulated and steroidogenic cell marker genes (3β-HSD, Cyp11a1, Star and Sf1) was dramatically increased in Wt1-/flox; Foxl2-cre ovaries. We also found that the meiosis of germ cells in Wt1-/flox; Foxl2-cre ovaries was delayed but not arrested. This study demonstrates that Wt1 is required for lineage maintenance of granulosa cells and inactivation of Wt1 results in pre-granulosa cells to steroidogenic cells transformation which in turn causes the defect of ovary development.
Wt1 基因编码一种核转录因子，特异性表达于卵巢颗粒细胞和睾丸支持细胞中。我们之前的研究表明，Wt1 对于支持细胞的谱系特化是必需的，而 Wt1 的失活导致支持细胞向 Leydig 样细胞转化。为了测试 Wt1 是否也参与卵巢发育过程中颗粒细胞的谱系维持，我们使用 Foxl2-cre 特异性地在原始颗粒细胞中缺失 Wt1。我们发现，雌性 Wt1-/flox;Foxl2-cre 小鼠不育，卵巢萎缩，没有观察到具有多层颗粒细胞的生长卵泡。在胚胎期，Wt1-/flox;Foxl2-cre 小鼠的卵巢中检测到大量 3β-HSD 阳性的类固醇生成细胞，这些细胞来源于表达 Foxl2 的原始颗粒细胞。定量结果表明，Wt1-/flox;Foxl2-cre 卵巢中颗粒细胞标记基因（Foxl2、Follistatin）的表达下调，而类固醇生成细胞标记基因（3β-HSD、Cyp11a1、Star 和 Sf1）的表达显著增加。我们还发现，Wt1-/flox;Foxl2-cre 卵巢中生殖细胞的减数分裂延迟但未停滞。本研究表明，Wt1 对于颗粒细胞的谱系维持是必需的，而 Wt1 的失活导致原始颗粒细胞向类固醇生成细胞转化，进而导致卵巢发育缺陷。
