New insights into epididymal biology and function

Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, 79430, USA.
Human Reproduction Update (Impact Factor: 10.17). 02/2009; 15(2):213-27. DOI: 10.1093/humupd/dmn055
Source: PubMed


The epididymis performs an important role in the maturation of spermatozoa including their acquisition of progressive motility and fertilizing ability. However, the molecular mechanisms that govern these maturational events are still poorly defined. This review focuses on recent progress in our understanding of epididymal function including its development, role of the luminal microenvironment in sperm maturation, regulation and novel mechanisms the epididymis utilizes to carry out some of its functions.
A systematic search of Pubmed was carried out using the search term 'epididymis'. Articles that were published in the English language until the end of August 2008 and that focused on the specific topics described above were included. Additional papers cited in the primary reference were also included.
While the majority of these findings were the result of studies in animal models, recent studies in the human epididymis are also presented including gene profiling studies to examine regionalized expression in normal epididymides as well as in those from vasectomized patients.
Significant progress has been made in our understanding of epididymal function providing new insights that ultimately could improve human health. The data also indicate that the human epididymis plays an important role in sperm maturation but has unique properties compared with animal models.

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    • "It could be posited that the detection of BAG6 in the epithelium, while unexpected, may relate to its ability to bind the hydrophobic region of misfolded proteins to direct their refolding or removal in the prevention protein aggregation (Payapilly and High, 2014; Wunderley et al., 2014). In this context, it is well known that the luminal protein content of the epididymis is uniquely susceptible to aggregation due to its high macromolecular and low water content (Cornwall, 2009). Indeed, such an environment has been shown to promote the formation of protein aggregates and/or amyloid structures where chaperones such as clusterin attend to protein quality control through their ability to interact with hydrophobic proteins and maintain their solubility (Cornwall et al., 2007; Cornwall, 2009). "
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    ABSTRACT: While a large cohort of sperm surface receptors underpin sperm-oocyte adhesion processes, our recent work has revealed that the molecular chaperone Heat Shock Protein A2 (HSPA2) is a key regulator of zona pellucida-receptor complex assembly in our own species. Indeed, in the infertile population, spermatozoa that fail to interact with the zona pellucida of the oocyte consistently lack HSPA2 protein expression. While the mechanisms behind this protein deficiency are under consideration, BCL2-associated athanogene 6 (BAG6) has been identified as a key regulator of HSPA2 stability in mouse germ cells. However, in the human, the presence of BAG family proteins remains completely uncharacterized. Consequently, this study aimed to determine the presence of BAG6 in human sperm cells and to characterize its putative interaction with HSPA2 throughout sperm cell development. BAG6 was shown to co-localize with HSPA2 in human testicular germ cells and epididymal spermatozoa. Similarly, BAG6 was identified in the equatorial region of non-capacitated spermatozoa but underwent a marked relocation to the anterior region of the head upon the induction of capacitation in these cells. Protein-protein interaction assays revealed the stable interaction of BAG6 and HSPA2 proteins in mature spermatozoa. Furthermore, examination of the spermatozoa of infertile men with zona pellucida binding defects, related to a lack of HSPA2, revealed a concomitant deficiency in BAG6 protein expression. In view of the findings described in this study, we propose that BAG6 is likely a key regulator of HSPA2 stability/function in human germ cells. Moreover, its under-representation in spermatozoa with zona pellucida binding deficiency suggests that BAG6 may be an important candidate to study for a further understanding of male idiopathic infertility.
    Molecular Human Reproduction 07/2015; 21(10). DOI:10.1093/molehr/gav041 · 3.75 Impact Factor
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    • "In rodents , a proximal segment distinct from the caput region is named the initial segment , and depicts unique histological characteristics . In addition to concentrate spermatozoa in the proximal segments and to store and protect the male gamete prior to ejaculation , the epididymal epithelium provides a defined sperm environment to accomplish maturation ( Robaire and Hermo , 1988 ; Turner , 1995 ; Cornwall , 2009 ; Dacheux and Dacheux , 2013 ) . An adequate epididymal luminal milieu is possible due to the blood – epididymal barrier , together with the endocytic and secre - tory functions of the epithelial cells ( Cyr et al . "
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    ABSTRACT: Mammalian fertilization involves a series of well-orchestrated cell-cell interaction steps between gametes, as well as among spermatozoa and somatic cells of both the male and female reproductive tracts. Cadherins are Ca2+-dependent glycoproteins that have been involved in cellular adhesion and signaling in somatic cells. Taking into account that Ca2+ ions are required during fertilization, the involvement of these proteins in adhesion events during this process can be anticipated. This report presents an overview on two members of classical cadherins, Epithelial (E-) and Neural (N-) cadherin in reproductive biology. Its provides evidence of studies done by several research groups about the expression of E- and N-cadherin during spermatogenesis, oogenesis and folliculogenesis, and their involvement in gamete transport in the reproductive tracts. Moreover, it describes current knowledge of E- and N-cadherin presence in cells of the cumulus-oocyte complex and spermatozoa from several mammalian species, and shows gathered evidence on their participation in different steps of the fertilization process. A brief summary on general information of both proteins is also presented.
    Developmental Biology 01/2015; 401(1). DOI:10.1016/j.ydbio.2014.12.029 · 3.55 Impact Factor
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    • "The epididymis is responsible for sperm concentration, transport and storage, but also promotes maturation by adding various proteins to the sperm surface [1]–[3]. Sperm maturation depends on the expression and secretion of proteins and glycoproteins by the epididymal epithelium, from the caput towards the cauda. "
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    ABSTRACT: The epididymis has an important role in the maturation of sperm for fertilization, but little is known about the epididymal molecules involved in sperm modifications during this process. We have previously described the expression pattern for an antigen in epididymal epithelial cells that reacts with the monoclonal antibody (mAb) TRA 54. Immunohistochemical and immunoblotting analyses suggest that the epitope of the epididymal antigen probably involves a sugar moiety that is released into the epididymal lumen in an androgen-dependent manner and subsequently binds to luminal sperm. Using column chromatography, SDS-PAGE with in situ digestion and mass spectrometry, we have identified the protein recognized by mAb TRA 54 in mouse epididymal epithelial cells. The ∼65 kDa protein is part of a high molecular mass complex (∼260 kDa) that is also present in the sperm acrosomal vesicle and is completely released after the acrosomal reaction. The amino acid sequence of the protein corresponded to that of albumin. Immunoprecipitates with anti-albumin antibody contained the antigen recognized by mAb TRA 54, indicating that the epididymal molecule recognized by mAb TRA 54 is albumin. RT-PCR detected albumin mRNA in the epididymis and fertilization assays in vitro showed that the glycoprotein complex containing albumin was involved in the ability of sperm to recognize and penetrate the egg zona pellucida. Together, these results indicate that epididymal-derived albumin participates in the formation of a high molecular mass glycoprotein complex that has an important role in egg fertilization.
    PLoS ONE 08/2014; 9(8):e103566. DOI:10.1371/journal.pone.0103566 · 3.23 Impact Factor
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