Human Sperm-Zona Pellucida Interaction is Inhibited by an Antiserum against a Hamster Sperm Protein1

Abstract

During epididymal transit, mammalian spermatozoa acquire new surface antigens that may participate in gamete interaction. We have previously described a 26-kDa (P26h) epididymal hamster sperm protein that we propose to be involved in fertilization. In this study, we have searched for an antigenically related protein in the human, and have found that an anti-P26h antiserum recognizes a 34-kDa (P34H) protein on Western blot of human sperm proteins. Immunostaining showed that this protein is localized on the acrosomal cap of human epididymal spermatozoa but not on testicular gametes. The effect of the anti-P26h antiserum on the fertilizing ability of human spermatozoa was evaluated by use of a human zona pellucida binding assay. Compared to the preimmune serum, the antiserum caused a highly significant decrease in the number of sperm bound per zona pellucida. This inhibition was not due to the induction of a premature acrosomal reaction nor to an effect on the motility of the spermatozoa. The antiserum recognizing the P34H human sperm protein had no effect on gamete fusion as determined by the zona-free hamster test. Our results suggest that the human spermatozoon acquires an epididymal protein that shares a common epitope(s) with the P26h hamster sperm protein. The possible involvement of this human sperm antigen in the binding to the zona pellucida is discussed.

Post-translational modifications in glycosylation status during epididymal passage and significance in fertility of a 33 kDa glycoprotein (MEF3) of rhesus monkey (Macaca mulatta)

“…The possible mechanism of inhibition of both in vivo fertilization and in vitro human sperm penetration in the zona-free hamster eggs could be due to sperm agglutination as demonstrated for human spermatozoa pretreated with the 33 kDa antiserum in mSA assay. These observations confirm the involvement of the 33 kDa glycoprotein in sperm function and fertility as reported for other proteins (Boue et al 1994, Mandal et al 2003. However, the specific roles of 33 kDa glycoprotein in sperm-egg interaction need to be examined in greater detail.…”

Novel epididymal proteins as targets for the development of post-testicular male contraception

“…It has been suggested that P34H is involved in sperm-ZP binding. This is supported by the results indicating that immunization against P34H inhibits sperm-zona binding in vitro (Boué et al 1994). Furthermore, the loss of P34H from sperm surface has been associated with idiopathic infertility in men (Boué & Sullivan 1996, Moskovtsev et al 2007, and human spermatozoa lacking P34H have been shown to be unable to bind to the extracellular matrix of oocyte (Boué & Sullivan 1996).…”

Switch of PMCA4 Splice Variants in Bovine Epididymis Results in Altered Isoform Expression during Functional Sperm Maturation

“…The vehicles of transfer are presumably the so-called epididymosomes, which are secreted in an apocrine manner by the epididymal epithelium (44,46). These vesicles have been found in mice (47), humans (48), and also in bulls where the glycosylphosphatidylinositol-anchored protein P25b plays an important role in the transfer process (49). Overall, this transfer improves sperm motility, zona pellucida binding, and the ability of the sperm to fuse with the egg plasma membrane (13, 28 -30, 46).…”