Primate Epididymis-Specific Proteins: Characterization of ESC42, a Novel Protein Containing a Trefoil-Like Motif in Monkey and Human

Abstract

Epididymal secreted proteins promote sperm maturation and fertilizing capacity by interacting with sperm during passage through the epididymis. Here we investigate the molecular basis of sperm maturation by isolating cDNA clones for novel epididymis-specific expressed sequences. Thirty-six novel cDNAs were isolated and sequenced from a subtracted Macaca mulatta epididymis library. The clones encode proteins with a range of motifs characteristic of protein-modifying enzymes, protease inhibitors, hydrophobic ligand-binding and transport proteins, extracellular matrix-interacting proteins, and transcription regulatory factors. The full length coding sequences were obtained for 11 clones representing a range of abundance levels. Expression of each is regionally localized and androgen regulated. The most abundant, ESC42, contains a cysteine-rich region similar to the signature binding domain of the trefoil family of motogenic wound repair proteins. The monkey and human proteins are nearly 90% identical. Immunohistochemical staining revealed that the protein is most abundant in the epithelium of the caput and is also present in the lumen and bound to sperm. The ESC42 gene, located on chromosome 20q11, contains two exons encoding two nearly identical predicted signal peptides and a third exon encoding the rest of the protein.

Human ribonuclease 9, a member of ribonuclease A superfamily, specifically expressed in epididymis, is a novel sperm-binding protein

“…We show here that human RNase 9 was expressed uniquely in the epididymis while remaining undetectable in twelve other tissues examined. It is consistent with the expression of rhesus monkey Esc461 [22] (homolog of human RNase 9) and mouse RNase 9 [13]. This indicates that human RNase 9 may have functions related to male reproduction system.…”

Identification, characterization, and evolution of a primate β-defensin gene cluster

“…33 The expression of defensins was not affected by castration in the corpus region, while caudal expression of defensins DEFB118-DEFB123 was not maintained at normal levels by exogenous testosterone, suggesting the requirement for additional testis factors as suggested previously. 25 Principal cells are particularly sensitive to circulating androgens and the androgen regulation of beta defensins may be cell and tissue specific. Regionspecific regulation of gene expression by androgens in the epididymis is complex and modulated by both epididymis and testis factors.…”

“…41 For analysis of the hormonal regulation of these defensins, castrated and hormone-replaced epididymides were used as previously reported. 25 For studies of the developmental regulation of defensins, macaque epididymis was obtained from the Oregon National Primate Research Center, Portland, OR, USA.…”

“…24 The rapid evolution of reproductive proteins may be driven by the selective forces of sperm competition, sexual selection and sexual conflict, individually, or in combination. 20 Previously, we identified the novel epididymal spermbinding protein DEFB118 25 and recently showed that DEFB118 has potent antibacterial activity. 26 The potential importance of the male reproductive tract defensins in host defense as well as male reproductive functions prompted us to investigate the 20q b-defensin gene cluster.…”

Molecular evolution of epididymal lipocalin genes localized on mouse chromosome 2

“…Also, lipocalins related to mE-RABP (Lcn5) are present in marsupial (Lamont et al, 1998), rat, rabbit, and boar epididymis (reviewed in . More recently, a cDNA encoding the monkey orthologue of mEP17(Lcn8) has been identified (Liu et al, 2001). Lcn2 has been found in mouse epididymis (Chu et al, 2000), and PGDS is present in zebrafish and Fugu (Lareyre, unpublished data).…”