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Query: UNIPROT:P06889 (Mol)
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The vascular cell responses to the type 1, 2, and 3 isoforms of transforming growth factor-beta (TGF-beta 1, TGF-beta 2, TGF-beta 3) were studied using bovine aortic endothelial (BAECs) and smooth muscle cells (BASMC3) as well as rat epididymal fat pad microvascular endothelia (RFCs). Three distinct bioassays indicated that TGF-beta elicits results that do not differ significantly from those of the TGF-beta 1 isoform in all three cell populations. These assays are: inhibition of proliferation, cell migration, and neovascularization. By contrast the cellular responses to TGF-beta 1 and TGF-beta 3 differed from those to TGF-beta 2. Three distinct receptor assays revealed the presence of type I and type II TGF-beta 1 cell surface binding proteins on BAECs, BASMCs, and RFCs. Experimentation to decipher cell surface binding by the different isoforms revealed that iodinated TGF-beta 1 bound to the surface of all three vascular cell types can be competed off in similar fashion by either TGF-beta 1 or TGF-beta 3; however, competition with TGF-beta 2 produced unique binding profiles dependent on the cell type examined. The ratios of type I to type II TGF-beta receptors in these three vascular cell types vary from 1:1 in BAECs to 1.5:1 in RFCs to 3:1 in BASMCs and can be correlated with the differences noted in cellular responses to TGF-beta 1 and TGF-beta 2 in proliferation, migration, and in vitro angiogenic assays.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1992 Jun
PMID:Modulation of vascular cell behavior by transforming growth factors beta. 163 50

Following Northern analysis, GGT mRNA was found predominantly within the caput epididymides and kidney. The size of mRNAs for kidney, caput, corpus, and ductus deferens were 2.2, 2.3, 2.2, and 2.3 kb, respectively, whereas cauda showed a doublet of 2.2 and 2.3 kb. GGT transpeptidation and hydrolytic activity within epididymal luminal fluids collected by micropuncture showed caput = corpus greater than cauda and corpus greater than caput greater than cauda, respectively. Caput luminal GGT transpeptidation activity was significantly inhibited by serine-borate and was optimal at pH 8.0. The calculated Km and Vmax values for hydrolysis of GSH by caput luminal GGT were 0.06 microM and 2.19 nmoles/min/microliters luminal fluid at pH 8.5 compared to 0.49 microM and 0.49 nmoles/min/microliters luminal fluid, respectively, at the physiological pH 6.5 of caput fluid. These studies would suggest that the epididymis can control the activity of luminal GGT by pH. Lower Km (0.12 microM) and higher Vmax (1.13 nmoles/min/microliters luminal fluid) values were also calculated when GSSG was used compared to GSH. Results from Triton X-114 partitioning experiments suggest that luminal GGT probably exists in both membrane bound and nonmembrane bound forms. Western blot analysis of proteins within epididymal luminal fluids revealed both subunits of GGT in all epididymal regions studied. However, two lower molecular bands, approximately 22 kDa and 21 kDa, were also observed in cauda fluid. It is suggested that as GGT is transported along the epididymal duct it undergoes degradation, which accounts for its loss of activity in the distal epididymal regions.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1991 Jan
PMID:Expression and activity of gamma-glutamyl transpeptidase in the rat epididymis. 167 40

Three staining procedures to detect sperm acrosome integrity were compared via electron microscopy. Stains were applied to epididymal, freshly ejaculated, in vivo capacitated, and sonicated sperm cells in addition to spermatozoa displaying sequentially removed plasma and outer and inner acrosomal membranes. Sequential membrane removal procedures resulted in removal of plasma membranes from 73% of all sperm cells, removal of plasma and outer acrosomal membranes from 74% of all sperm cells, and removal of plasma and outer and inner acrosomal membranes from 87% of all sperm cells as determined by electron microscopy. Live/dead staining results were not statistically different from subjective microscopic motility evaluations (P less than 0.005) for epididymal, sonicated, freshly ejaculated, and in vivo capacitated sperm samples. All three stains assessed were similarly capable of detecting the acrosome status of freshly ejaculated and of sonicated spermatozoa compared to data obtained by electron microscopy (P = 0.010). However, only the Bryan-Akruk stain afforded data that were closely correlated with data obtained via electron microscopy for all sperm types assessed; the latter included in vivo capacitated spermatozoa and sperm cells rendered free of plasma membranes. Results confirmed an earlier report by successfully effecting sequential removal of rabbit acrosomal membranes and documented use of the Bryan-Akruk acrosomal stain for evaluation of sperm cell populations for fertilizing ability. These findings should prove useful in further investigations of mechanisms involved in achievement of fertilizing ability by rabbit spermatozoa.
Mol Reprod Dev 1990 May
PMID:Evaluation of rabbit sperm acrosomal integrity and fertilizing ability by use of vital stains. 169 80

To investigate surface glycoprotein changes during post-testicular maturation, plasma membranes were isolated from proximal caput, distal caput, and cauda epididymal rat spermatozoa. Membrane glycoproteins were identified on Western blots of SDS-PAGE fractionated samples using biotinylated lectins and Vecta-stain reagents; these were compared to glycoproteins present in cauda epididymal luminal fluid. Lens culinaris agglutinin, Pisum sativum agglutinin, peanut agglutinin, wheat germ agglutinin, Ricinus communis agglutinin, Ulaex europaeus agglutinin, and Dolichol biflorus agglutinin each bound a specific subset of the polypeptides present. Several types of glycoprotein changes were noted including their appearance, loss, alteration of staining intensity, and alteration of electrophoretic mobility. Some maturation-dependent sperm surface glycoproteins co-migrated with glycoproteins present in epididymal fluid. This approach of direct analysis of the glycoproteins in purified plasma membranes identifies a broader spectrum of maturation-related surface changes occurring within the epididymis than are noted with surface labeling procedures.
Mol Reprod Dev 1991 Aug
PMID:Glycoprotein changes in the rat sperm plasma membrane during maturation in the epididymis. 171 14

Plasma membranes isolated from cauda epididymal and ejaculated boar sperm were inserted into planar lipid bilayers and examined for the presence of ion channels. Channel fusion was frequently observed; the most prominent was a nonselective cation channel which conducted K, Na, Cs, Ca, and Ba. Channel opening did not show a strict dependence on voltage but was partially blocked by verapamil, nitrendipine, and ruthenium red. A channel with these characteristics was observed when plasma membranes were isolated by high-pressure nitrogen cavitation (650 psi, 78% sperm head plasma membranes) or at very low nitrogen pressures (50 psi, 90% sperm head plasma membranes), suggesting that this channel may be present in the plasma membrane overlying the sperm head.
Mol Reprod Dev 1991 Oct
PMID:Ion channels in boar sperm plasma membranes: characterization of a cation selective channel. 172 6

The epididymal tubule is a dynamic structure, in which spermatozoa undergo distinct physiological and morphological changes. The epithelial cells lining the ductuli vary dramatically in their histochemical and cytological properties according to the region of the tubule in which they are located. Additionally, regional variation is observed regarding the biosynthetic, secretory, and absorptive properties of the epithelial cells. Using in situ histochemical analysis, we document here the region-specific expression of a variety of genes that are transcriptionally active in the adult rat epididymis. Radiolabeled antisense riboprobes were used to localize, within the efferent duct/caput epididymis, transcripts encoding protein B/C, protein D/E (acidic epididymal glycoprotein), sulphated glycoprotein 1, sulphated glycoprotein 2, cellular retinol-binding protein, and the neuroendocrine peptide precursor proenkephalin. Each species of mRNA exhibits a unique pattern of hybridization, revealing that gene transcription within the efferent duct/caput epididymis is also highly region specific. This observation may partially elucidate the molecular basis underlying the phenomenon of regional alterations in the composition of protein factors within the tubule lumen.
Mol Reprod Dev 1991 Sep
PMID:In situ histochemical analysis of region-specific gene expression in the adult rat epididymis. 178 83

Clusterin (sulfated glycoprotein-2) is a heterodimeric glycoprotein synthesized and secreted by rat Sertoli cells. An antigenically similar form is synthesized and secreted by the epididymis. The goal of this study was to define the epididymal regions in which clusterin is present and the regions in which clusterin is secreted and interacts with developing spermatozoa. Seminiferous tubule (STF), caput, corpus, and cauda fluids were collected by micropuncture and/or microperfusion and two-dimensional Western blot analysis was performed with a polyclonal antibody directed against Sertoli cell clusterin. Clusterin was found in both STF and epididymal fluid. STF contained predominantly the clusterin heavy chain (45 kd); however, a 70 Kd heterodimer was present under nonreducing conditions. Two subunits of clusterin with lower molecular weights (41 kd, heavy chain; 32 kd, light chain) and higher isoelectric points were present in the luminal fluid of all epididymal regions. The intraluminal levels of the heavy and light chains decreased from caput to cauda. Analysis by two-dimensional gel electrophoresis of proteins secreted directly into the epididymal luminal fluid revealed that clusterin was secreted by caput epithelium and not by the corpus and cauda epithelium. Western blots of membrane extracts from testicular, caput, and cauda spermatozoa revealed that testicular clusterin was associated with testicular sperm and epididymal clusterin with predominantly caput sperm. Our findings suggest that clusterin is secreted into the caput epididymal lumen, where it binds to sperm and then dissociates from sperm to be endocytosed by cells of the distal epididymal epithelium.
Mol Reprod Dev 1991 Sep
PMID:In vivo secretion and association of clusterin (SGP-2) in luminal fluid with spermatozoa in the rat testis and epididymis. 178 89

During its reproductive period, the epididymis of the lizard Lacerta vivipara produces large amount of proteins among which "L" proteins are very prominent components. L proteins have been characterized as an androgen dependent protein family composed of 9 elements of identical MW and different pHi. An epididymal cDNA library was performed and a cDNA clone, C73 was isolated using a specific anti L immunoserum. We tested the tissue specificity and the androgen dependency of this clone in different physiological and experimental conditions by dot-blot analysis. The aminoacid deduced sequence of the C73 clone revealed that it strictly corresponds to the NH2 terminal sequence of the LIV element of the family. It consists of a 151 amino acids mature protein with a 17.2 kDa MW that present homologies with a rat epididymal protein supposed to be a retinoic acid binding protein.
Cell Mol Biol 1991
PMID:Molecular cloning and characterization of a cDNA encoding for the mature form of a specific androgen dependent epididymal protein. 180 85

The decrease in motility of porcine cauda epididymal sperm was less than that of caput epididymal sperm in the medium containing bicarbonate. This may be due to the difference of sensitivity of adenylate cyclase to bicarbonate between mature and immature sperm; activation of mature sperm enzyme by bicarbonate was higher than that of immature sperm. Nondialysable fraction of egg yolk prevented the decrease in motility of immature sperm in the presence of bicarbonate, but it was not effective for the motility of mature sperm under the same condition, because only bicarbonate is sufficient for the maintenance of its motility. In the absence of bicarbonate, both mature and immature sperm required egg yolk to maintain motility. The favorable effect of egg yolk on the motility is ascribed to the enhancement of intracellular cAMP level. Partial fractionation of egg yolk showed that water-insoluble lipoprotein fraction contains factor(s) which activates adenylate cyclase in sperm plasma membrane. This is the first report in which high molecular weight activator of the sperm enzyme was demonstrated.
Mol Reprod Dev 1991 Feb
PMID:Water insoluble fraction of egg yolk maintains porcine sperm motility by activating adenylate cyclase. 184 69

The surface membrane of mammalian spermatozoa is known to undergo considerable conformational and organizational changes during epididymal maturation. However, much less is known about remodelling of intracellular membranes. In this communication we have used specific immunological markers to study the behavior of several antigens both on and within rat spermatozoa as they mature in the epididymis. Four monoclonal antibodies (McAbs) designated 5B1, 1B5, 2D6, and 1B6 were used to probe testicular and caput and cauda epididymal spermatozoa by indirect immunofluorescence and immunogold labeling techniques. None of the McAbs bound to testicular spermatozoa; in all cases, they became reactive only on spermatozoa which had reached the caput epididymis. McAb 5B1 was restricted to the outer acrosomal membrane (OAM) of the acrosomal cap domain. The epitope first appeared on antigen(s) with molecular mass (Mr) of approximately 200 kDa in immature spermatozoa, but later in mature spermatozoa the antigen(s) had Mr of approximately 160 kDa. The antigen(s) recognized by 1B5 McAb on the other hand was initially distributed over the OAM of the entire acrosomal domain (cap + equatorial segment), but during maturation it became progressively more restricted in area until in cauda spermatozoa only the anterior tip of the OAM bound the McAb. McAb 2D6 also bound to the entire OAM and acrosomal contents of caput spermatozoa, but, unlike 5B1 and 1B5 McAbs, reactivity was transient. That is, staining was first detected in caput spermatozoa but then disappeared in corpus and cauda spermatozoa. In contrast to all of the above, 1B6 McAb bound to the surface membrane overlying the entire head domain of caput spermatozoa, but during maturation it became restricted to the postacrosomal domain. These results indicate that, in addition to remodeling of the surface membrane during epididymal maturation, extensive processing of intracellular membrane antigens also takes place and that it is very active within the acrosome. The nature of these intracellular processing events remains to be elucidated, but they may have important consequences for membrane fusion and cell recognition phenomena during fertilization.
Mol Reprod Dev 1991 Aug
PMID:Alterations in distribution of surface and intracellular antigens during epididymal maturation of rat spermatozoa. 188 15


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