Human sperm degradation of zona pellucida proteins contributes to fertilization

Reproductive Biology and Endocrinology

Research

Fernando Larrea¹  Mayel Chirinos¹  Analilia Saldívar-Hernández¹  María E. González-González¹  Claudia L. Treviño²  Ana Sánchez-Tusié²  Pablo López³  Israel Maldonado-Rosas³ 

[1] Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, D.F. 14080, México, Mexico;Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, UNAM, 62210, Cuernavaca, Mexico;Instituto Mexicano de Alta Tecnología Reproductiva (Inmater), D.F. 11000, Mexico, Mexico;

关键词: Human sperm;    Zona pellucida;    ZP penetration;    Fertilization;   

DOI  :  10.1186/s12958-015-0094-0

 received in 2015-07-13, accepted in 2015-08-12,  发布年份 2015

来源: Springer

【 摘 要 】

ndThe mammalian oocyte extracellular matrix known as the zona pellucida (ZP) acts as a barrier to accomplish sperm fusion with the female gamete. Although penetration of the ZP is a limiting event to achieve fertilization, this is one of the least comprehended stages of gamete interaction. Even though previous studies suggest that proteases of sperm origin contribute to facilitate the passage of sperm through the ZP, in human this process is not yet fully understood. The aim of this study was to determine the ability of human sperm to degrade recombinant human ZP (rhZPs) proteins and to characterize the proteases involved in this process.MethodsPurified rhZP2, rhZP3 and rhZP4 proteins were incubated with capacitated sperm and the proteolytic activity was determined by Western blot analysis. To further characterize the proteases involved, parallel incubations were performed in the presence of the protease inhibitors o-phenanthroline, benzamidine and MG-132 meant to block the activity of metalloproteases, serine proteases and the proteasome, respectively. Additionally, protease inhibitors effect on sperm-ZP binding was evaluated by hemizona assay.ResultsThe results showed that rhZPs were hydrolyzed in the presence of capacitated sperm. O-phenanthroline inhibited the degradation of rhZP3, MG-132 inhibited the degradation of rhZP4 and benzamidine inhibited the degradation of the three proteins under investigation. Moreover, hemizona assays demonstrated that sperm proteasome inhibition impairs sperm interaction with human native ZP.ConclusionsThis study suggests that sperm proteasomes could participate in the degradation of ZP, particularly of the ZP4 protein. Besides, metalloproteases may be involved in specific degradation of ZP3 while serine proteases may contribute to unspecific degradation of the ZP. These findings suggest that localized degradation of ZP proteins by sperm is probably involved in ZP penetration and may be of help in understanding the mechanisms of fertilization in humans.

【 授权许可】

CC BY   
© Saldívar-Hernández et al. 2015