Yuchuan Zhou,1 Min Zheng,1 Qixian Shi,2 Li Zhang,1 Wei Zhen,1 Wenying Chen,2 and Yonglian Zhang1,3*PLoS ONE. 2008; 3(12): e4106.
Published online 2008 December 31. doi: 10.1371/journal.pone.0004106.
1Shanghai Key Laboratory for Molecular Andrology, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
2Unit of Reproductive Physiology, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, China
3Shanghai Institute of Planned Parenthood Research, Shanghai, China
Dominik Hartl, Editor
Yale University School of Medicine, United States of America
* E-mail: ylzhang@sibs.ac.cn
Abstract
Mammalian sperm capacitation is an essential prerequisite to fertilizion. Although progress had been made in understanding the physiology and biochemistry of capacitation, little is known about the potential roles of epididymal proteins during this process. Here we report that HongrES1, a new member of the SERPIN (serine proteinase inhibitor) family exclusively expressed in the rat cauda epididymis and up-regulated by androgen, is secreted into the lumen and covers the sperm head. Co-culture of caudal sperms with HongrES1 antibody in vitro resulted in a significant increase in the percentage of capacitated spermatozoa. Furthermore, the percentage of capacitated spermatozoa clearly increased in rats when HongrES1 was down-regulated by RNAi in vivo. Remarkably, knockdown of HongrES1 in vivo led to reduced fertility accompanied with deformed appearance of fetuses and pups. These results identify HongrES1 as a novel and critical molecule in the regulation of sperm capacitation and male fertility. | 
