While uterine epithelium secretes eggshell matrix proteins to regulate eggshell structural organization, uterovaginal junction (UVJ) epithelium supports sperm storage in tubules (SST). Here, we examined the presence of OCX36, OC-116 and OC-17 eggshell matrix proteins in SSTs. Two experimental lines of hens displaying either a long (F+ line) or a short (F- line) potential to store sperm were used, before and 24h after insemination. Using immunohistochemistry and western blot, we analyzed the presence of OC-116, OC-17 and OCX36 proteins in the SSTs. Using lectin and calcium staining, we examined the presence in SSTs of Gal/GalNAc (Galactose/N-acetylgalactosamine) and Glc/GlcNAc (Glucose/N-acetylglucosamine) glycans, as well as calcium ions. Our results indicate that in both F+ and F- hens, the eggshell matrix proteins OC-116 and OCX36 were identified in SST cells and lumen, in contact with spermatozoa. The OC-17 protein was found associated with calcium in F+ and F- hens, only in the SST lumen 24h after insemination. Glycans Gal/GalNAc and Glc/GlcNAc were found to be more abundant in the apical cytoplasmic area of the SST cells of F+ hens than in that of F- hens after insemination. This is the first report demonstrating the presence in SSTs of the OC-116, OC-17 and OCX36 eggshell matrix proteins, and their concomitant presence with Gal/GalNAc and Glc/GlcNAc glycans, as well as with calcium. Our results suggest that the OC-116, OC-17 and OCX36 eggshell matrix proteins may be involved in sperm storage.

Avian uterine fluid (UF) and uterovaginal sperm storage tubules (SST) are key components in accepting sperm in SST, maintaining sperm function for several weeks, releasing sperm from SST and their ascent through the uterus. To improve the understanding of sperm storage processes requires investigating UF and SST. This study aimed to identify proteins modulated by sperm in the hen’s genital tract and to highlight their role during sperm storage. Two genetic lines of hens exhibiting long (F+) or short (F−) sperm storage ability were used. GeLC MS/MS analysis was used to establish a quantitative inventory of proteins regulated after insemination in both lines. The proteomic data are available via ProteomeXchange with identifier PXD013514. Immunohistochemistry was used to identify high (ANXA4/ANXA5/OCX32) and low (HSPA8/PIGR) fertility markers in the uterovaginal junction. Our results demonstrated that sperm induced a significant and rapid change in the UF proteomic content and also in the SST epithelium. In F+ hens, mobilization of the ANXA4 protein in the apical part of SST cells after insemination was associated with increased levels of some proteoglycans and binding proteins, and also antimicrobial eggshell matrix protein (OCX32) in the UF. We also observed increased levels of lipid transporters involved in egg formation (VTG1-2, APOA1-4-H). In F− hens, insemination induced increased levels of PIGR in both UF and SST, of ANXA5 in SST, of UF enzymes exhibiting metallopeptidase activity and mucins. In conclusion, sperm induced significant changes in the UF proteomic content. This study also provides evidence that the SST immune system plays a major role in regulating sperm storage.

In birds, oviductal cells play a crucial role in the storage of sperm via cell-to-cell communication including extracellular vesicles (EV). We developed a culture of oviductal organoids enriched in sperm storage tubules (SSTorg) to demonstrate the release of EV. SSTorg were cultured for 24 h and added to live (LV), frozen (FZ) and lysed (LY) avian sperm, seminal plasma (SP), avian sperm conditioned medium (CM), or bovine sperm (BV). Western blot demonstrated that SSTorg contained EV protein markers, valosin-containing protein (VCP), heat shock proteins (HSP90AA1, HSPA8), and annexins (ANXA2, A4, A5). Co-culture with LV significantly decreased the intracellular level of all these proteins except HSPA8. Immunohistochemistry confirmed this result for VCP and ANXA4. LY, CM, SP and BV had no effect on the intracellular level of these proteins, whereas FZ induced a decrease in ANXA2, A4 and A5. In culture media, VCP and HSP90AA1 signals were detected in the presence of LV, FZ, BV, LY, CM and SP, but no ANXA4 signal was observed in the presence of FZ and SP. ANXA2 and A5 were only detected in the presence of LV. The most abundant EV were less than 150 nm in diameter. ANXA4 and A5 were more abundant in EV isolated from the SSTorg culture medium. This study provides a useful culture system for studying interactions between SST cells and sperm. We demonstrated the release of EV by SSTorg in vitro, and its regulation by sperm. This may be of crucial importance for sperm during storage in hens.

Cet article fait partie du dossierActualités en reproduction équine