Unveiling the role of the Notch signaling pathway and dtx4a/b: Implications for Paralichthys olivaceus ovarian development

Elucidating the regulatory mechanisms of ovarian development and oocyte maturation is important for sex-controlled breeding in aquaculture. Among all regulatory pathways, the Notch signaling pathway has been found to play a crucial role in mammalian oocyte development, but its function in teleost has not been reported. In this study, resveratrol, an activator of the Notch signaling pathway, was injected into the ovary of Paralichthys olivaceus in vivo initially, which caused ovary atrophy and partial detachment of internal oocytes. Concurrently, the expression levels of genes related to oocyte development showed significant changes, with which an opposite result could be observed in the in vitro inhibition experiment. To further explore the mechanisms by which Notch signaling are regulated in oocytes, the function of two E3 ubiquitin ligase members (Dtx4) identified from our previous comparative transcriptome analysis was studied. Among them, the expression of dtx4b was significantly higher than that of dtx4a in the ovary. ISH results showed that they were both intensively distributed in oocyte, and they showed different expression patterns during oocyte maturation process. Subsequently, the protein interactions of Dtx4a with Notch1/2- NICD and Dtx4b with Notch2-NICD were verified by fluorescence co-localization and yeast two-hybrid assay. Finally, the negative correlation of dtx4a/b with Notch signaling pathway was verified by dual-luciferase assay and knock down experiment in vitro. These results revealed the regulatory role of dtx4a/b on the Notch signaling pathway for the first time in teleost and provided solid reference for the study of fish gonadal development. •Notch signaling pathway affects ovarian development of P. olivaceus.•dtx4a and dtx4b experienced functional differentiation.•Dtx4a/b regulate Notch signaling pathway by interact with Notch1/2.