PDGF Signaling in Sertoli Cell Cilia and Seminiferous Tubule Morphogenesis
Immature porcine testicular Sertoli cells possess primary cilia, organelles that transmit extracellular signals into the cell. A yet unidentified ciliary signal in Sertoli cells has been found necessary for in vitro morphogenesis of tubules and testicular organoids. Herein, we hypothesized that platelet-derived growth factor receptor alpha (PDGFRα) signaling through the cilia of the Sertoli cells modifies cell migration and extracellular matrix (ECM) production, consequently altering in vitro formation of testicular organoids and seminiferous tubules. Immunocytochemistry revealed PDGFRα was present on Sertoli cell cilia as well as the rest of the cell membrane and cytoplasm. Inhibiting PDGFRα signaling did not prevent organoid and tubule formation. However, it appeared to correlate with ablation of cytoplasmic extensions from the surface of the in vitro formed tubules. Inhibition of PDGFRα signaling resulted in reduction in cell area, increase in the percentage of cells with prominent peripheral paxillin expression, and increase in the number of ciliated cells and cilia length. Immunohistochemistry revealed that cilia, which colocalized with PDGFRα, were positioned away from the basement membrane of the seminiferous tubules, close to the Sertoli cell nuclei, in an area that was occupied with Sertoli cell cytoplasm. When observed via transmission electron microscopy, Sertoli cell cilia exhibited ciliary pockets around their axoneme. These results demonstrate that PDGFRα activity in Sertoli cells can influence in vitro tubule morphogenesis, possibly by altering cell cytoskeleton, cell-ECM interaction, and cilia. However, the role of cilia-specific signaling remains to be determined.
Ahmadi Jeyhoonabadi, M. (2023). PDGF signaling in Sertoli cell cilia and seminiferous tubule morphogenesis (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.