Evidence that a functional fertilin-like ADAM plays a role in human spermoolemmal interactions

Abstract

Fertilin is a protein initially identified in guinea pig spermatozoa; it is the prototype of a larger family of conserved, proteins designated as a disintegrin and a metalloproteinase (ADAM). These heterodimers which consist of alpha and beta subunits, containing metalloproteinase-like and disintegrin-like domains, appear to play a role in mammalian fertilization. Peptides derived from the disintegrin domains of two ADAMs, fertilin and cyritestin, interfere with gamete adhesion and sperm-egg membrane fusion in non-human species. It has been suggested that fertilin-beta binds to an oolemmal integrin, and it is proposed that the tripeptide FEE (Phe-Glu-Glu) is the integrin recognition sequence in human fertilin-beta. We evaluated whether fertilin beta plays a role in human fertilization by studying the effects of a linear octapeptide containing the FEE sequence, SFEECDLP, and a scrambled octapeptide with the same amino acids, SFPCEDEL, on the incorporation of human spermatozoa by human zona-free eggs. The effects of G4120, a potent RGD-containing (Arg-Gly-Asp) thioether-bridged cyclic peptide which blocks both fibronectin and vitronectin receptors, and the relationship between FEE- and RGD-receptor interactions on sperm-egg interactions were also studied. The FEE-containing peptide, but not the scrampled peptide, inhibited sperm adhesion to oocytes and their penetration, over the range 1-5 microM. The inhibition induced by SFEECDLP was reversible and occurred only in the presence of peptide itself. The G4120 peptide exhibited 10-fold less inhibitory effects on sperm adhesion and penetration than did SFEECDLP. When combined, SFEECDLP and G4120 exhibited strong inhibition of both adhesion and penetration at concentrations that individually had been ineffective, suggesting co-operation between the two receptor-ligand interactions during fertilization. We propose that a fertilin-like molecule is functionally active on human spermatozoa and that its interaction with an oolemmal integrin receptor plays a role in fertilization in humans.

Quantitative analysis of sperm mRNA in the pig: relationship with early embryo development and capacitation

“…In the present study, we investigated the association between MYC, CYP19, ADAM2, PRM1 and PRM2 mRNA levels in spermatozoa and early embryo development in the pig using real-time PCR and IVF analyses. We focused on these mRNAs because it has been suggested that MYC, CYP19, ADAM2, PRM1 and PRM2 serve as markers of sperm motility and/or fertility in humans Naz et al 1991;Bronson et al 1999;Aquila et al 2002;Aoki et al 2006). The results of the IVF assays revealed that the ratio of blastocysts to cleaved embryos did not differ significantly between groups (Table 3; Table S2).…”

“…In the present study, we investigated whether the distribution of sperm mRNAs coding for MYC, aromatase (CYP19), fertilin-b (ADAM2), protamine 1 (PRM1) and protamine 2 (PRM2), which have been reported to be related to sperm quality or early embryo development in humans (Naz et al 1991;Bronson et al 1999;Aquila et al 2002;Aoki et al 2006), is involved in early embryonic development in the pig and whether a marker gene could be suggested to evaluate sperm quality in the pig. We also investigated whether the mRNA abundance of each gene changes after the induction of capacitation and whether these changes are involved in early embryonic development in the pig.…”

CD9 controls the formation of clusters that contain tetraspanins and the integrin α6β1, which are involved in human and mouse gamete fusion

“…The role of fertilin ␤ in the fusion process is highlighted by the fact that sperm lacking this protein have a 50% decrease ability to fuse with the oocyte (Cho et al, 1998). In human, a peptide containing the integrin recognition sequence of human fertilin ␤ (Phe-Glu-Glu) was shown to also inhibit sperm adhesion to oocytes and their penetration (Bronson et al, 1999).…”

Mammalian Sperm Fertility Related Proteins

“…These proteins are involved in sperm-oocyte penetration and sperm migration in the oviduct 37. In humans, ADAM 2 binds to the integrin receptor of oolemma (integrin α 6 β 1 ) and functions in sperm-oocyte interaction 29, 38. Additionally, ADAM 18 (tMDC III) contains the integrin binding motif which might be involved in sperm-oocyte binding in humans 39.…”