Yi Hongyang, Liang Weizheng, Yang Sumei, Liu Han, Deng Jiayu, Han Shuhong, Feng Xiaohui, Cheng Wenjie, Chen Yonglong, Hang Jing, Lu Hongzhou, Ran Rensen
National Clinical Research Centre for Infectious Diseases, the Third People'S Hospital of Shenzhenand, the Second Affiliated Hospital of Southern University of Science and Technologyaq , Shenzhen, 518112, China.
Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
BMC Biol. 2025 Feb 27;23(1):62. doi: 10.1186/s12915-025-02168-0.
Melanin pigmentation in oocytes is a critical feature for both the esthetic and developmental aspects of oocytes, influencing their polarity and overall development. Despite substantial knowledge of melanogenesis in melanocytes and retinal pigment epithelium cells, the molecular mechanisms underlying oocyte melanogenesis remain largely unknown.
Here, we compare the oocytes of wild-type, tyr and mitf Xenopus tropicalis and found that mitf oocytes exhibit normal melanin deposition at the animal pole, whereas tyr oocytes show no melanin deposition at this site. Transmission electron microscopy confirmed that melanogenesis in mitf oocytes proceeds normally, similar to wild-type oocytes. Transcriptomic analysis revealed that mitf oocytes still express melanogenesis-related genes, enabling them to complete melanogenesis. Additionally, in Xenopus tropicalis oocytes, the expression of the MiT subfamily factor tfe3 is relatively high, while tfeb, mitf, and tfec levels are extremely low. The expression pattern of tfe3 is similar to that of tyr and other melanogenesis-related genes. Thus, melanogenesis in Xenopus tropicalis oocytes is independent of Mitf and may be regulated by other MiT subfamily factors such as Tfe3, which control the expression of genes like tyr, dct, and tyrp1. Furthermore, transcriptomic data revealed that changes in the expression of genes related to mitochondrial cloud formation represent the most significant molecular changes during oocyte development.
Overall, these findings suggest that further elucidation of Tyr-dependent and Mitf-independent mechanisms of melanin deposition at the animal pole will enhance our understanding of melanogenesis and Oogenesis.
卵母细胞中的黑色素沉着对于卵母细胞的美学和发育方面都是一个关键特征，影响其极性和整体发育。尽管对黑素细胞和视网膜色素上皮细胞中的黑色素生成已有大量了解，但卵母细胞黑色素生成的分子机制仍 largely 未知。
在这里，我们比较了野生型、tyr 和 mitf 热带爪蟾的卵母细胞，发现 mitf 卵母细胞在动物极表现出正常的黑色素沉积，而 tyr 卵母细胞在该部位没有黑色素沉积。透射电子显微镜证实 mitf 卵母细胞中的黑色素生成正常进行，类似于野生型卵母细胞。转录组分析表明 mitf 卵母细胞仍表达与黑色素生成相关的基因，使其能够完成黑色素生成。此外，在热带爪蟾卵母细胞中，MiT 亚家族因子 tfe3 的表达相对较高，而 tfeb、mitf 和 tfec 的水平极低。tfe3 的表达模式与 tyr 和其他黑色素生成相关基因的表达模式相似。因此，热带爪蟾卵母细胞中的黑色素生成独立于 Mitf，可能受其他 MiT 亚家族因子如 Tfe3 调控，Tfe3 控制 tyr、dct 和 tyrp1 等基因的表达。此外，转录组数据表明与线粒体云形成相关的基因表达变化是卵母细胞发育过程中最显著的分子变化。
总体而言，这些发现表明进一步阐明动物极黑色素沉积的 Tyr 依赖性和 Mitf 独立性机制将增进我们对黑色素生成和卵子发生的理解。
