Protease activity involvement in the passage of mammalian sperm through the zona pellucida

Abstract

The interaction between acrosome-reacted sperm and zona pellucida proteins is not yet fully understood. Serine protease acrosin and its zymogen proacrosin have been proposed to fulfi ll this function due to their capacity to bind zona pellucida glycoproteins. However, the molecular mechanism underlying this interaction has been merely speculative. Here we show that fucoidan (a sulfated polysaccharide) and solubilized zona pellucida glycoproteins, but not soybean trypsin inhibitor, are able to detach bound spermatozoa, which suggests that live sperm binds to the zona pellucida in a non-enzymatical way. Interestingly, mild proteolytic digestion with acrosin or trypsin does not modify the structure of the zona pellucida, but rather results in fewer spermatozoa binding to the zona. These results agree with a model where the active site of acrosin digests the zona pellucida and binds through the polysulfate-binding domain through a three-dimensional zona structure rather than a single ligand.

Singular features of fertilization and their impact on the male reproductive system in eutherian mammals

“…Kim et al (2008), Moreno et al (2011), Sutovsky (2011 and Ferrer et al (2012)). Nevertheless, the highly derived design of the eutherian sperm head does imply a mode of penetration in which physical factors dominate.…”

Viscous constraints on microorganism approach and interaction

“…However, during bacterial conjugation (Griffiths et al 2000), zooplankton mating (Strickler 1998;Kiørboe 2007) or colonization an organism approaches another member of the same species of similar size. Approach to larger targets also occurs during fertilization of an egg by sperm (Moreno et al 2011) or when bacteria find new habitats by approaching marine snow, small biological debris which provides a local nutrient source and habitat in the ocean (Kiørboe et al 2003;Grossart et al 2006).…”

Involvement of a P2X7 Receptor in the Acrosome Reaction Induced by ATP in Rat Spermatozoa

“…The acrosome is an acid compartment derived from Golgi vesicles and lysosomes containing hydrolytic enzymes that supposedly help the sperm to cross the zona pellucida (Barros et al, ; Moreno, ; Codelia et al, ; Moreno and Alvarado, ; Yanagimachi, ). In addition, the AR changes the post‐acrosomal membrane in order to prepare the sperm to fuse with the egg's plasma membrane (Barros et al, ; Inoue et al, ; Moreno et al, )…”

“…The acrosome is an acid compartment derived from Golgi vesicles and lysosomes containing hydrolytic enzymes that supposedly help the sperm to cross the zona pellucida (Barros et al, 1992;Moreno, 2003;Codelia et al, 2005;Moreno and Alvarado, 2006;Yanagimachi, 2011). In addition, the AR changes the post-acrosomal membrane in order to prepare the sperm to fuse with the egg's plasma membrane (Barros et al, 1992;Inoue et al, 2005;Moreno et al, 2011) During the AR, there is a massive increase in the intracellular free calcium that triggers the membrane fusion machinery between the outer acrosomal membrane and the adjacent plasma membrane (Darszon et al, 2005). In addition, the AR dissipates the acid intra-acrosomal pH, and soluble proteins and active proteases are released to the extracellular milieu (Barros et al, 1992;Codelia et al, 2005;Buffone et al, 2009a,b).…”