Spatiotemporal characteristics of RPL24 expression in the yak oviduct and its regulatory mechanism on epithelial cell proliferation via DDX3X/DDX5.

To investigate the role of RPL24 in regulating yak (Bos grunniens) oviductal epithelial cell (OEC) phenotype via DDX3X/DDX5, we developed a polyclonal anti-RPL24 antibody. Immunohistochemistry (IHC) revealed widespread RPL24 expression in infundibulum, ampulla, and isthmus epithelial cells during the follicular, luteal, and gestational stages. Changes in RPL24, DDX3X, and DDX5 expression levels in fallopian tube tissues were quantitatively analyzed using western blotting. Differences in expression were significant among different reproductive cycles and anatomical sites. Tissue and cellular immunofluorescence confirmed that RPL24 and DDX3X primarily co-localized in the cytoplasm across all stages, with minor DDX3X nuclear expression, whereas DDX5 was predominantly nuclear. siRNA-mediated RPL24 knockdown resulted in the most significant downregulation (approximately 0.436-fold) compared to that in the blank control group (p < 0.0001). However, DDX3X protein levels were significantly reduced at 72 h (0.01 ≤ p < 0.05) to approximately 0.894-fold of the blank control. DDX5 protein levels were significantly reduced at 72 h (0.001 ≤ p < 0.01) to approximately 0.845-fold of the blank control. Furthermore, this knockdown significantly reduced PCNA levels (0.001 ≤ p < 0.01) and increased the levels of the apoptosis marker Bax (0.001 ≤ p < 0.01). EdU assay confirmed the suppression of epithelial cell proliferation. Our findings demonstrated that RPL24 positively regulates DDX3X/DDX5 protein abundance and may directly or indirectly affect OEC proliferation via this pathway. These findings provide new molecular targets and a theoretical basis for understanding the regulation of Fallopian tube function in mammals.