Yao Bo, Zhou Li, Wang Yang, Xia Wei, Gui Jian-Fang
State Key Laboratory of Freshwater Ecology and Biotechnology, Wuhan Center for Developmental Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Wuhan, China.
J Exp Zool A Ecol Genet Physiol. 2007 Apr 1;307(4):207-19. doi: 10.1002/jez.361.
SOX3 has been suggested to play significant roles in gametogenesis and gonad differentiation of vertebrates, but the exact cellular localization evidence is insufficient and controversial. In this study, a protogynous hermaphrodite fish Epinephelus coioides is selected to analyze EcSox3 differential expression and the expression pattern in both processes of oogenesis and spermatogenesis by utilizing the advantages that gonad development undergoes transition from ovary to intersexual gonad and then to testis, and primordial germ cells and different stage cells during oogenesis and spermatogenesis are synchronously observed in the transitional gonads. The detailed and clear immunofluoresence localization indicates that significantly differential expression and dynamic changes of Sox3 occur in the progresses of gametogenesis and sex reversal, and EcSOX3 protein exists in the differentiating primordial germ cells, oogonia, and different stage oocytes of ovaries, and also in the differentiating primordial germ cells and the Sertoli cells of testis. One important finding is that the EcSox3 expression is a significant time point for enterable gametogenesis of primordial germ cells because EcSOX3 is obviously expressed and localized in primordial germ cells. As EcSox3 continues to express, the EcSOX3-positive primordial germ cells develop toward oogonia and then oocytes, whereas when EcSox3 expression is ceased, the EcSOX3-positive primordial germ cells develop toward spermatogonia. Therefore, the current finding of EcSOX3 in the differentiating primordial germ cells again confirms the potential regulatory role in oogenesis and germ cell differentiation. The data further suggest that SOX3, as a transcription factor, might have more important roles in oogenesis than in spermatogenesis.
已有研究表明，SOX3在脊椎动物的配子发生和性腺分化中发挥重要作用，但确切的细胞定位证据不足且存在争议。在本研究中，选择了一种雌性先熟的雌雄同体鱼类斜带石斑鱼，利用其性腺发育从卵巢过渡到雌雄同体性腺再到睾丸，以及在过渡性腺中同步观察到原生殖细胞和卵子发生及精子发生过程中不同阶段细胞的优势，来分析EcSox3的差异表达及其在卵子发生和精子发生过程中的表达模式。详细而清晰的免疫荧光定位表明，Sox3在配子发生和性逆转过程中存在显著的差异表达和动态变化，EcSOX3蛋白存在于卵巢中正在分化的原生殖细胞、卵原细胞和不同阶段的卵母细胞中，也存在于睾丸中正在分化的原生殖细胞和支持细胞中。一个重要发现是，EcSox3的表达是原生殖细胞进入配子发生的一个重要时间点，因为EcSOX3在原生殖细胞中明显表达并定位。随着EcSox3持续表达，EcSOX3阳性的原生殖细胞向卵原细胞进而向卵母细胞发育，而当EcSox3表达停止时，EcSOX3阳性的原生殖细胞则向精原细胞发育。因此，目前在正在分化的原生殖细胞中发现EcSOX3再次证实了其在卵子发生和生殖细胞分化中的潜在调控作用。数据进一步表明，作为一种转录因子，SOX3在卵子发生中可能比在精子发生中发挥更重要的作用。
