De novo protein synthesis by bovine uterine tube (oviduct) epithelial cells changes during co-culture with bull spermatozoa

Polypeptides secreted by uterine tube epithelial cells (UTEC) may facilitate sperm cell capacitation in vivo. This experiment evaluated the effect of sperm-UTEC co-culture on de novo protein synthesis by epithelial cells of the tubal isthmus. Comparisons of the patterns of proteins secreted into medium were made between four culture groups incubated for 24 h in the presence of ³⁵S-methionine: group 1, sperm cells alone; group 2, control UTEC monolayers; group 3, UTEC co-cultured with sperm cells; and group 4, UTEC partitioned by a diffusible membrane from sperm cells during culture. Two-dimensional PAGE followed by fluorography was used to analyze conditioned medium containing secreted proteins from each group. The experiment was replicated four times. Sperm cells alone secreted no detectable proteins, whereas control UTEC monolayers produced a wide array of polypeptides. Sperm cells attached to UTEC in co-culture within minutes, and the resultant protein profile for these UTEC differed markedly from that of the control UTEC. Several new proteins were seen only from co-cultured cells, whereas other protein groups that were present with UTEC alone were absent in the co- culture medium of group 3. The protein pattern expressed by UTEC partitioned from sperm cells (group 4) was intermediate between that of the group 2 controls and that of co-cultured UTEC (group 3). In summary, the attachment of sperm cells to the UTEC during co-culture changed the types and quantities of proteins secreted into the conditioned medium as compared to those of control UTEC monolayers. Exposure to sperm cells without attachment stimulated some, but not all, of the changes seen in protein production from the UTEC.