Localization of epididymal protease inhibitor in adult rat and its transcription profile in testis during postnatal development

Abstract

To investigate the expression pattern of rat Eppin (epididymal protease inhibitor; official symbol Spinlw1), we detected mRNA transcripts and subsequent protein translation of Eppin in several sorts of tissues by RT-PCR and western blotting. Then immunohistochemistry was performed for more detailed observation. The testicular transcription level was monitored by real-time PCR throughout postnatal development. We found that rat Eppin was specifically expressed in the testis and epididymis. The testicular transcription was slight in neonatal (1-day) and infantile stages (5-, 7- and 10-day). It increased sharply thereafter, with maximum expression level (about 38-fold compared with that of 1-day old rat) detected in prepubertal stage (15-day). Then a slightly declined but stable level (about 20-fold compared with that of 1-day old rat) was kept in pubertal-early adult (30-day) and adult (60-day) stages of postnatal maturation. In the adult rat, EPPIN protein was mainly localized in the elongated spermatids and epididymal epithelial cells. Sperm in the epididymal duct were all covered with EPPIN and its level kept constant during incubation under conditions used to achieve capacitation. Its stage-specific expression in the testis suggests that EPPIN may be important during spermatogenesis especially for the spermatid elongation. The abundant production of epididymal EPPIN indicated indirectly that it might play a role in the function of the epididymis.

Epididymal protease inhibitor (EPPIN) is differentially expressed in the male rat reproductive tract and immunolocalized in maturing spermatozoa

“…In the present study, we characterized the expression and cellular distribution of EPPIN in rat tissues. In contrast to an earlier study (Bian et al, 2009), in which an Eppin transcript was only detected in the rat testis and epididymis, we found that EPPIN expression was abundant in these tissues, but also present in the rat vas deferens, seminal vesicles, and brain. In these novel sites of expression, EPPIN may act as an antibacterial protein, provide protease inhibitor activity, and/or play further roles that still remain unknown.…”

“…These results demonstrated the critical role of androgens in maintaining EPPIN expression in the epididymis. Our results are consistent with previous studies demonstrating the up-regulation of EPPIN in rat testis (Bian et al, 2009) and mouse epididymis (Sivashanmugam et al, 2003) with post-natal development and its down-regulation in the mouse testis after knocking out the androgen receptor in Sertoli cells (Denolet et al, 2006;Willems et al, 2010).…”

“…Animal models are important tools for providing further insights into the molecular mechanisms underlying EPPIN functions and evolution, as well as for evaluating the effectiveness and safety of new lead contraceptive compounds targeting this molecule in preclinical trials. Although different studies have characterized Eppin gene expression and regulation in mice (Sivashanmugam et al, 2003; Denolet et al, 2006; Schauwaers et al, 2007; De Gendt et al, 2009; Willems et al, 2010), studies in rats have been limited (Bian et al, 2009). Therefore, the present study fully characterizes the expression and cellular distribution of EPPIN in rat tissues and its in vivo regulation by changes in circulating androgens in the epididymis.…”

New frontiers in nonhormonal male contraception

“…Immunocontraception that targets different sperm antigens to affect fertilization and fertility has also been investigated. For instance, immunization of male monkeys with human recombinant epididymal protease inhibitor (EPPIN), a serine protease inhibitor expressed by the testis and epididymis [32–34], altered sperm progressive motility (as the ability of anti-EPPIN-treated spermatozoa to utilize cAMP was compromised [35]) and resulted in reversible infertility [36,37]. Additional studies reported that EPPIN binds to semenogelin I [38], a protein in the coagulum that renders sperm immobile [39], and anti-EPPIN antibodies appear to affect the interaction between EPPIN and semenogelin [40].…”

Expressions of Semenogelin Gene in Male Syrian Hamsters according to Photoperiod

“…One of the components released from the seminal vesicles is the semenogelin (SEMG). It has been reported to bind to the epididymal protease inhibitor (EPPIN) that is synthesized and secreted from the Sertoli cells of the testes and epididymal epithelial cells (Sivashanmugam et al, 2003;Bian et al, 2009). The complex that the EPPIN anatomically produced in advance combines with SEMG (EPPIN-SEMG complex) protects the spermatozoa from the microbial attacks (Yenugu et al, 2004;de Lamirande, 2007).…”