Viable and morphologically normal boar spermatozoa alter the expression of heat‐shock protein genes in oviductal epithelial cells during co‐culture in vitro

Abstract

The principal aim of this study was to determine if boar spermatozoa influence the expression of four selected chaperone and heat-shock protein (HSP) genes-namely clusterin (CLU), HSP90AA1, HSPA5, and HSPA8-in oviductal epithelial cells (OECs) during in vitro co-culture. All corresponding proteins of these genes were previously identified in a sperm-interacting, 70-kDa soluble fraction derived from apical plasma membranes of OECs. The present study also sought to determine whether or not: (i) spermatozoa must directly bind to OEC for an effect on gene expression to be elicited and (ii) reproductive and nonreproductive epithelial cell types (LLC-PK1, pig kidney) respond equivalently, in terms of alterations in chaperone and HSP gene expression, during co-culture with sperm. Spermatozoa induced a significant upregulation (P < 0.05) in HSP90AA1 and HSPA5 in OECs after 3 hr, and in HSPA8 after 6 hr of co-culture when they were in direct contact with epithelial cells. Conversely, no upregulation of HSP transcription was observed when spermatozoa did not directly bind to OECs. Spermatozoa also induced a significant upregulation (P < 0.05) of the same three genes when in direct contact with LLC-PK1 cells, but the timing occurred later than with OECs. Interestingly, the extent of HSP gene upregulation induced by direct contact of spermatozoa with epithelial cells was dependent on sperm-binding index and on the viability and morphological quality of the bound sperm population. In conclusion, the upregulation of HSP genes caused by direct contact between spermatozoa and OECs, rather than nonreproductive epithelial cells, suggests HSPs could play an integral role in the modulation of sperm function in the oviductal reservoir.

Sperm selection in the female mammalian reproductive tract. Focus on the oviduct: Hypotheses, mechanisms, and new opportunities

“…A later study in mice found that insemination induced de novo gene transcription in the female reproductive tract, stimulated specifically by spermatozoa and not by seminal plasma [61]. These results were later confirmed by both in vitro and in vivo experiments involving insemination responses in pigs and cattle [62][63][64][65][66]. Interestingly, similar responses to the arrival of spermatozoa have also been noted in avian sperm storage glands [67][68][69].…”

“…It appears that the process is initiated rapidly, with changes being detectable within 1 hour [66]. Moreover, the importance of direct contact between oviductal epithelial and spermatozoa in initiating gene expression responses was demonstrated by in vitro studies, where porcine oviductal epithelial cells failed to initiate the production of heat shock proteins when direct contact was prevented [65].…”

Genes Encoding Mammalian Oviductal Proteins Involved in Fertilization are Subjected to Gene Death and Positive Selection

“…It has neither been lost nor duplicated in the sampled species, contrary to HSPA8, which was duplicated in orangutan, rat, sheep, and pig. Heat shock proteins A5 and A8 play a role in the modulation of boar sperm function in the oviductal reservoir (Yeste et al 2014). …”

Roles of the reproductive tract in modifications of the sperm membrane surface

“…Yeste et al and Moein-Vaziri et al showed that when epithelial cells in the oviduct are co-cultured with viable spermatozoa, the gene expression profile of these epithelial cells is altered. These changes coincide with the restoration of sperm membrane integrity and fluidity that are essential for sperm capacitation [47, 48]. Based on morphology, the oviduct can be subdivided into four segments, the uterotubulo junction, isthmus, ampulla, and infundibulum (from the uterus toward the ovary); each segment contains similar sorts of cells, but in different proportions.…”