Mice Lacking Two Sperm Serine Proteases, ACR and PRSS21, Are Subfertile, but the Mutant Sperm Are Infertile In Vitro1

Abstract

Although sperm serine protease and proteasome have long been believed to play an important role in the fertilization process, the molecular mechanism is still controversial. In this study, we have produced double-knockout mice lacking two sperm serine proteases, ACR and PRSS21, to uncover the functional role of the trypsinlike activity in fertilization. The double-knockout male mice were subfertile, likely owing to the incompleteness of fertilization in the oviductal ampulla. Despite male subfertility, the mutant epididymal sperm exhibited the inability to undergo acrosomal exocytosis on the zona pellucida (ZP) surface and to traverse the ZP, thus resulting in the failure of fertilization in vitro. The double-knockout epididymal sperm were also defective in penetration through the cumulus matrix to reach the ZP. When epididymal sperm were artificially injected into the uterus of wild-type mice, the 2-cell embryos, which had previously been fertilized by double-knockout sperm, were recovered at a low but significant level. The mutant epididymal sperm were also capable of fertilizing the oocytes in the presence of uterine fluids in vitro. These data demonstrate that the trypsinlike protease activity of ACR and PRSS21 is essential for the process of sperm penetration through the cumulus matrix and ZP in vitro, and suggest that the female reproductive tract partially compensates for the loss of the sperm function. We therefore conclude that the sperm trypsinlike activity is still important but not essential for fertilization in vivo in the mouse.

Genetic and phenotypic influences on copulatory plug survival in mice

“…Consistent with a hypothesis of sexual conflict (Stockley, 1997), recently mated females upregulate proteases thought to assist in plug degradation (Kelleher and Pennington, 2009;Dean et al, 2011), whereas male seminal fluid is enriched for protease inhibitors , although proteases and their inhibitors have additional roles in reproduction (Wolfner, 2002;Kawano et al, 2010). Also, plug-forming proteins, proteases and protease inhibitors all tend to evolve rapidly (Dorus et al, 2004;Clark and Swanson, 2005;Kelleher et al, 2007;Lawniczak and Begun, 2007;Ramm et al, 2008;Wong et al, 2008;Dean and Nachman, 2009;Dean et al, 2011) as predicted for genes involved in sexual conflict (Swanson and Vacquier, 2002;Clark et al, 2006).…”

Network Analyses of Sperm–Egg Recognition and Binding: Ready to Rethink Fertility Mechanisms?

“…Easily, it is possible to explain this finding by the coexistence of a redundant mechanism as a safety strategy: prss21 and acrosin exert similar (but likely not identical) function during the SERB process, thus the failure of a only one of them did not affected the efficiency of whole process. Only the contemporaneous removal of both of them caused a detectable negative effect (Kawano et al, 2010).…”

Acrosome-reacted mouse spermatozoa recovered from the perivitelline space can fertilize other eggs

“…They suggested that such spermatozoa are able to reenter the ZP with the aid of this residual acrosin. Even though spermatozoa from Acrosin-KO mice can fertilize eggs (14), this enzyme and some other proteases (including PRSS21) on acrosome-reacted spermatozoa might work synergistically to assist sperm passage through the ZP (15).…”