Identification of Androgen-Induced Proteins in Human Epididymis

Abstract

Androgenic stimulation (0.1 microM testosterone or 5 alpha-dihydrotestosterone in the medium) of cultured human epididymal tubules increased the synthesis of five proteins, identified by their mobility relative to albumin (Ra) in polyacrylamide gels as 0.31, 0.43, 0.67, 0.81 and 1.01. This effect was inhibited by the simultaneous presence of 10 microM cyproterone acetate in the medium. The caput epididymidis was the most active region in the production of these proteins and a gradient of decreasing activity was found in successive segments. The appearance of induced proteins in the culture medium suggests their secretory nature, while some data indicate that androgens may also affect the secretory process. Bands corresponding to Ra 0.31, 0.43, 0.68 and 1.01 were found in caput and cauda epididymidis fluids, while bands coincident with Ra 0.31 and 0.43 were consistently found in extracts (0.5 M NaCl) of caudal spermatozoa. Preliminary determinations of molecular weight and isoelectric point for the different bands yielded the following results: Ra 0.31, 38,000 and 5.8; Ra 0.43, 21,000 and 6.2; Ra 0.68, 69,000 and 5.1; Ra 0.81, 13,900 and 6.8; and Ra 1.01, 29,000 and 6.8.

Transient appearance of CRES protein during spermatogenesis and caput epididymal sperm maturation

“…The proximal region or caput epididymidis is particularly active in protein synthesis and secretion, which is consistent with it being the site where the initiation events of sperm maturation occur (Jones et al, 1981;Tezon et al, 1985; 0 1995 WILEY-LISS, INC. 1990). To selectively identify genes expressed in the caput epididymidis, we utilized a caput epididymal-specific probe to screen a mouse epididymal cDNA library.…”

Epididymis is a principal site of retrovirus expression in the mouse.

“…Sperm transit time through the epididymis during maturation affords ample exposure to virus particles for absorption (2 (27,28). The absence of virus expression in the testis suggests, however, that if androgens are involved, their influence is mediated through tissue-specific regulation.…”

Human Sperm-Zona Pellucida Interaction is Inhibited by an Antiserum against a Hamster Sperm Protein1

“…Tezon et al [20,21] and Ross et al [22] have also demonstrated that certain androgen-dependent proteins secreted by the epididymis become bound to human spermatozoa. Acquisition of new proteins by the sperm surface during epididymal transit is correlated with the increased capacity of human spermatozoa to bind to zona-free hamster oocytes [23,24].…”