GP-83 and GP-39, two glycoproteins secreted by human epididymis are conjugated to spermatozoa during maturation

Abstract

Surface glycoconjugates of spermatozoa are modified during epididymal maturation, which is closely related to the development of sperm function. In addition, recognition of surface glycoconjugates is one of very critical events in sperm-oocyte interaction. The binding of carbohydrate-specific lectins to the human sperm surface during epididymal maturation has been investigated. However, the glycoproteins responsible for lectin binding in sperm maturation are not well documented. This study used wheat germ agglutinin (WGA), peanut agglutinin (PNA) and concanavalin A (Con-A) to identify sperm maturation-related glycoproteins in human epididymis. Histochemical localization revealed that the binding sites of WGA, PNA and Con-A were mainly in the principal cells and luminal contents of the human epididymis, but not in the interstitial regions. Each lectin displayed a fairly distinct regional localization. On Western blots probed with WGA and Con-A, glycoproteins of 83 kDa (GP-83) and 39 kDa (GP-39) were identified in the sperm extracts, epididymal fluid and tissue extracts of the corpus and cauda epididymides, but not in the caput. PNA identified GP-83 in the same manner as WGA and Con-A, but did not recognize GP-39. These results suggest that lectin-binding glycoproteins GP-83 and GP-39 found on mature spermatozoa may be secreted by the principal cells of corpus and cauda epididymis, and conjugated to spermatozoa during their transit in human epididymis.

Ultrastructure of the male genital ducts of the clearnose skateRaja eglanteria

“…Golgi bodies were not a prominent feature in these cells which adds weight to the suggestion that the bulk of the cytoplasmic granules were probably secondary lysosomes and the result of ingestion via the microvillous surface; such activity has also been described in H. portusjacksoni (Jones and Lin,'92). However, the epididymis has also been shown to secrete a wide variety of enzymes and proteins in all species studied (Feuchter et al, '87;Dacheux et al, '89;Syntin et al, '96;Cooper, '98;Liu et al, 2000) and therefore protein biosynthesis must also be active in this tissue. Additional incidental luminal components include remnants of Sertoli cells.…”

Partial characterization, sperm association and significance of N- and O-linked glycoproteins in epididymal fluid of rhesus monkeys (Macaca mulatta)

“…Lectins have been widely used as probes in the examination of glycocomponents of the cell surface and secretions in a variety of species (Young et al 1986, Arenas et al 1996, Navneetham et al 1996, Calvo et al 2000. The use of lectins to probe Western blots of SDS-PAGE-fractionated plasma membranes of spermatozoa from various segments of the epididymis in mouse, rat, rhesus monkey and human spermatozoa (Rankin et al 1989, Srivastava & Olson 1991, Liu et al 2000, Srivastav 2000) examines a wide diversity of carbohydrate moieties and permits direct analysis of glycocomponents on Western blots of fractionated proteins, within specific epididymal segments and, furthermore, provides evidence for different mechanisms that may generate these changes.…”

“…Some of the surface differences demonstrated by spermatozoa as they migrate through the epididymis have been shown to result from the binding of epididymal secretory proteins to the sperm surface, by using approaches such as: coincident migration of epididymal and sperm proteins on polyacrylamide gels (Rankin et al 1989, Srivastava & Olson 1991, Srivastav 2000; radiolabelling techniques using both in vitro and in vivo binding of labelled epididymal proteins to spermatozoa (Moore et al 1994); direct binding of protein to spermatozoa (Fournier-Delpech et al 1997); and immunochemical techniques (Xu et al 1997, Gatti et al 2000 in several species, including both non-human primates (Frö hlich & Young 1996) and human (Tezon et al 1985, Focarelli et al 1998, Martin Ruiz et al 1998, Liu et al 2000.…”

“…Although the characterization, significance and role of epididymal glycoproteins have been studied in many primate species including human (Focarelli et al 1998, Kirchhoff et al 1998, Martin Ruiz et al 1998, Liu et al 2000, Yeung et al 2000b, these are poorly understood in the epididymis of the rhesus monkey (Navneetham et al 1996), an animal model commonly used for preclinical testing of drugs. Previous work from this laboratory has demonstrated maturation-dependent changes in the glycoprotein profile of purified plasma membrane of spermatozoa from rhesus monkey epididymis, and a few of these glycoproteins co-migrated with proteins present in the caudal epididymal fluid.…”

Post-translational modifications in glycosylation status during epididymal passage and significance in fertility of a 33 kDa glycoprotein (MEF3) of rhesus monkey (Macaca mulatta)

“…Although the characterization, significance, and role of epididymal glycoproteins has been studied in many primate species including the human (Focarelli et al 1998, Kirchhoff et al 1998, Liu et al 2000, Cohen et al 2001, Busso et al 2005, these are poorly understood in the rhesus epididymis (Srivastav 2000, Srivastav et al 2004), an animal model commonly used for preclinical testing of drugs. Previous work from this laboratory (Srivastav 2000, Srivastav et al 2004) on the glycosylation status of sperm membrane and EF proteins during sperm maturation in rhesus epididymis led to the identification of three major maturation-dependent, heavily glycosylated proteins viz.…”