Regulation of Female Folliculogenesis by Tsp1a in Nile Tilapia (Oreochromis niloticus)

• Main Authors: Mimi Jie, He Ma, Li Zhou, Jiahong Wu, Minghui Li, Xingyong Liu, Deshou Wang
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: International Journal of Molecular Sciences
• Subjects: Nile tilapia; thrombospondin1; CRISPR/Cas9; folliculogenesis
• Online Access: https://www.mdpi.com/1422-0067/21/16/5893

<b> </b>TSP1 was reported to be involved in multiple biological processes including the activation of TGF-β signaling pathways and the regulation of angiogenesis during wound repair and tumor growth, while its role in ovarian folliculogenesis remains to be elucidated. In the present study, Tsp1a was found to be expressed in the oogonia and granulosa cells of phase I to phase IV follicles in the ovaries of Nile tilapia by immunofluorescence. <i>tsp1a</i> homozygous mutants were generated by CRISPR/Cas9. Mutation of <i>tsp1a</i> resulted in increased oogonia, reduced secondary growth follicles and delayed ovary development. Expression of the cell proliferation marker PCNA was significantly up-regulated in the oogonia of the mutant ovaries. Furthermore, transcriptomic analysis revealed that expressions of DNA replication related genes were significantly up-regulated, while cAMP and MAPK signaling pathway genes which inhibit cell proliferation and promote cell differentiation were significantly down-regulated. In addition, aromatase (Cyp19a1a) expression and serum 17β-estradiol (E2) concentration were significantly decreased in the mutants. These results indicated that lacking <i>tsp1a</i> resulted in increased proliferation and inhibited differentiation of oogonia, which in turn, resulted in increased oogonia, reduced secondary growth follicles and decreased E2. Taken together, our results indicated that <i>tsp1a</i> was essential for ovarian folliculogenesis in Nile tilapia.