The function of Pt-TGFβRI in spermatogenesis of the swimming crab Portunus trituberculatus.

The Portunus trituberculatus is an economically important aquaculture species, and understanding its spermatogenesis is critical for ensuring sustainable industrial development. Spermatogenesis is regulated by multiple signaling pathways, but the role of the TGFβ signaling pathway remains poorly understood. TGFβRI is a key receptor in the TGFβ signaling pathway. In this study, Pt-TGFβRI was identified and found to be highly expressed in the testes, suggesting its potential critical role in spermatogenesis. Immunofluorescence staining localized Pt-TGFβRI and its downstream components Pt-Smad2/3 and Pt-Smad4 to the acrosome of mature spermatozoa, indicating the involvement of Pt-TGFβRI in acrosome formation. To further explore its function, the activity of Pt-TGFβRI was inhibited using the specific inhibitor SB431542. qPCR, WB, and immunofluorescence analyses demonstrated that inhibition of Pt-TGFβRI altered the expression and distribution of Pt-Smad2/3 and Pt-Smad4, suggesting that Pt-TGFβRI regulates acrosome formation through signal transduction. Comparative transcriptomic analysis between inhibitor-treated and control testes identified 2317 DEGs. GO and KEGG enrichment analyses revealed that Pt-TGFβRI may regulate spermatogenesis by influencing physiological metabolism, ion homeostasis, and RNA processing of spermatogenic cells. PPI network analysis identified key hub genes, including SUMO, AKT, SMAD4, and CDK2, indicating that Pt-TGFβRI plays a crucial role in spermatogenic cell differentiation, proliferation, apoptosis, and meiosis in the testes of P. trituberculatus. This study elucidates the potential regulatory functions of Pt-TGFβRI in spermatogenesis, providing novel insights into the role of the TGFβ signaling pathway in crustacean spermatogenesis and a theoretical foundation for further exploration of molecular mechanisms underlying crustacean sperm development.