Roles of piwil1 gene in gonad development and gametogenesis in Japanese flounder, Paralichthys olivaceus

PIWI family member piwil1, which associates with Piwi-interacting RNA (piRNA), is responsible in regulation of germ cell differentiation and maintenance of reproductive stem cells. In this study, we analyzed the piwil1 gene in Paralichthys olivaceus. Bioinformatics analysis and structure prediction showed that piwil1 had the conserved domains: PAZ domain and PIWI domain. Expression analysis during embryonic development implied that piwil1 gene was maternally inherited. The tissue distribution showed a sexually dimorphic gene expression pattern, with higher expression level in testis than ovary. In situ hybridization results demonstrated that piwil1 was predominantly distributed in oogonia, oocytes, sertoli cells and spermatocytes. A CpG island was predicted in the 5'-flanking region of piwil1 gene, and its methylation levels showed significant disparity between males and females, indicating that the sexually dimorphic expression of piwil1 gene might be regulated by methylation. Furthermore, we explored the distinct roles of human chorionic gonadotropin and 17 alpha-methyltestosterone in regulating the expression of piwil1, and found that piwil1 was interacting with the HPG axis hormones. These results indicated that piwil1 might play a crucial role in gonadal development and gametogenesis in Paralichthys olivaceus.

PIWI家族成员piwil1与Piwi相互作用RNA（piRNA）相关，负责生殖细胞分化的调控以及生殖干细胞的维持。在本研究中，我们分析了牙鲆（Paralichthys olivaceus）中的piwil1基因。生物信息学分析和结构预测表明，piwil1具有保守结构域：PAZ结构域和PIWI结构域。胚胎发育过程中的表达分析表明piwil1基因是母源遗传的。组织分布呈现出性别二态性的基因表达模式，在睾丸中的表达水平高于卵巢。原位杂交结果显示piwil1主要分布在卵原细胞、卵母细胞、支持细胞和精母细胞中。在piwil1基因的5'侧翼区域预测到一个CpG岛，其甲基化水平在雄性和雌性之间存在显著差异，这表明piwil1基因的性别二态性表达可能受甲基化调控。此外，我们探究了人绒毛膜促性腺激素和17α - 甲基睾酮在调控piwil1表达中的不同作用，发现piwil1与下丘脑 - 垂体 - 性腺（HPG）轴激素相互作用。这些结果表明piwil1可能在牙鲆的性腺发育和配子发生中起关键作用。