Endoplasmic reticulum protein 29 (ERp29), a protein related to sperm maturation is involved in sperm-oocyte fusion in mouse

Abstract

BackgroundSperm-oocyte fusion is a critical step in fertilization, which requires a series of proteins from both spermatozoa and oocyte to mediate membrane adhesion and subsequent fusion. A rat spermatozoa membrane protein is endoplasmic reticulum protein 29 (ERp29), which significantly increases on the sperm surface as well as in the cytoplasm of epididymal epithelia from caput to cauda as the sperm undergo epididymal maturation. Moreover, ERp29 facilitates viral infection via mediating membrane penetration. We determined if in addition to promoting sperm maturation ERp29 may also play a role in facilitating gamete fusion during the fertilization process.MethodsLaser scanning confocal microscopy (LSCM) and Western blot analysis were employed to probe for ERp29 protein in BALB/c mouse epididymal and acrosome-reacted spermatozoa. We prepared rabbit polyclonal antibodies against mouse recombinant ERp29 (rERp29) to characterize: 1) fertilization rate (FR); 2) fertilization index (FI); 3) sperm motility and 4) acrosome reaction (AR).ResultsConfocal microscopy indicated that ERp29 was partially localized at the sperm head of the epididymal caput as well as over the whole head and part of the principal piece of the tail region from the epididymal cauda. However, when the acrosome reacted, ERp29 remained in the equatorial and post-acrosomal regions of the sperm head, which is the initial site of sperm-oocyte membrane fusion. Such localization changes were confirmed based on the results of Western blot analysis. Furthermore, the antibodies against mouse rERp29 inhibited the spermatozoa from penetrating into the zona pellucida (ZP)-free oocytes. The functional blocking antibodies reduced both mouse sperm-oocyte FR and FI at concentrations of 100 and 200 micro g/ml compared with pre-immunized rabbit IgG or with anti-mouse recombinant bactericidal/permeability-increasing protein (BPI, a sperm surface protein unrelated to sperm-oocyte fusion) antibodies (100 micro g/ml), but they had no effect on sperm motility and AR.ConclusionThis study demonstrates that ERp29 on mouse spermatozoa membrane changes during epididymal transit and AR. Accordingly, in mice this protein may be one of the important factors involved in sperm fertilization by facilitating sperm-oocyte membrane fusion.

Distribution Pattern(s) of Sperm Protein at 22 kDa (SP22) on Fresh, Cooled and Frozen/Thawed Equine Spermatozoa and Expression of SP22 in Tissues from the Testes and Epididymides of Normal Stallions

“…Sperm surface proteins (O'Rand et al 1984;Burks et al 1995;Cohen et al 1996;Lea et al 1996;Hamatani et al 2000;Yang et al 2010;Ying et al 2010) and seminal plasma proteins (Killian et al 1993;Capkova and Peknicova 1997) have been associated with fertility (O'Rand et al 1984), but in most cases, these proteins were related to fertility based on the demonstration of sperm-egg binding in vitro. In contrast, the expression of a membrane-bound sperm protein at 22 kDa (SP22) has been shown to be associated with fertility in the rat using both in vivo and in vitro models (Klinefelter et al 2002).…”

Surviving in a toxic world: transcriptomics and gene expression profiling in response to environmental pollution in the critically endangered European eel

“…Several experimental studies on gene expression have shown genetic responses to pollutants in eel [31-36]. However, large-scale transcriptomic approaches in the European eel have been limited to the study of osmoregulation [37] and comparative gene expression analysis between sympatric European and American eel larvae in the Sargasso Sea [38].…”

ERp29 affects the migratory and invasive ability of human extravillous trophoblast HTR‐8/SVneo cells via modulating the epithelial‐mesenchymal transition

“…[ 25,26 ] In addition, ERp29 is a crucial factor involved in sperm fertilization via facilitating sperm‐oocyte membrane fusion. [ 27 ] The main findings of our study are as follows: the upregulation of ERp29 was identified in the severe pre‐eclamptic placentas, and the upregulation of ERp29 could block HTR‐8/SVneo cell metastasis, while downregulation of ERp29 had the opposite effect.…”