Effects of testosterone on protein synthesis in rat seminal vesicles analysed by two-dimensional gel electrophoresis

Transgelin: an androgen-dependent protein identified in the seminal vesicles of three Saharan rodents

During the breeding season, a major androgen-dependent protein with an apparent molecular weight of 21 kDa was isolated and purified from the seminal vesicles of three Saharan rodents (MLVSP21 from Meriones libycus, MSVSP21 from Meriones shawi, and MCVSP21 from Meriones crassus). The 21-kDa protein was isolated and purified from soluble seminal vesicle proteins of homogenate by one-dimensional polyacrylamide gel electrophoresis (SDS-PAGE). Using polyclonal antibodies directed against POSVP21 (Psammomys obesus seminal vesicles protein of 21 kDa), a major androgen-dependent secretory protein from sand rat seminal vesicles, identified previously as transgelin, we showed an immunological homology with POSVP21 by immunoblotting. These three major androgen-dependent proteins with a same apparent molecular weight of 21 kDa designated as MLVSP21 (Meriones libycus seminal vesicles protein of 21 kDa), MSVSP21 (Meriones shawi seminal vesicles protein of 21 kDa), and MCVSP21 (Meriones crassus seminal vesicles protein of 21 kDa) were localized by immunohistochemistry and identified by applying a proteomic approach. Our results indicated that the isolated proteins MLSVP21, MSSVP21, and MCSVP21 seem to correspond to the same protein: the transgelin. So that transgelin can be used as a specific marker of these rodent physiological reproduction mechanisms.

POSVP(21), a major secretory androgen-dependent protein from sand rat seminal vesicles, identified as a transgelin

The seminal vesicles of adult sand rat contain a major secretory protein band (MW 21 kDa) designated as Psammomys obesus seminal vesicles protein of 21 kDa (POSVP(21)). This protein is abundant in secretions, regulated by androgens and also present in the vaginal plug. POSVP(21) accounts for over 22.3% of soluble proteins from homogenate during the breeding season, 13.3% during the middle season and 5.3% during the hormonal regression season. It is absent during the non-breeding season. POSVP(21) is localized in the cytoplasm of epithelial cells and in secretory products in the lumen. It presents an immunological homology with two epididymal proteins with the same molecular weight and a high degree of homology with transgelin from rat (Rattus norvegicus).

Androgen-dependent synthesis/secretion of caltrin, calcium transport inhibitor protein of mammalian seminal vesicle

Effects of androgen status on the synthesis and secretion of rat caltrin have been studied by three different procedures: a) immunocytochemistry in seminal vesicle tissues; b) polyacrylamide gel electrophoresis and Western immunostaining of seminal vesicle secretion; and c) evaluation of trypsin inhibitory activity of the seminal vesicle secretion. Rat caltrin has been immunolocalized in cells of the secretory epithelium, specifically in the electron-lucent halo of secretory granules which store and transport proteins to the lumen. No caltrin immunoreaction was detected 14 days postcastration, and the ultrastructure of the epithelial cells was markedly altered. SDS-PAGE and Western blotting of the seminal vesicle secretion revealed alterations in the protein pattern and loss of the caltrin-related immunoreactive bands. The 54-kDa caltrin-precursor protein and the 6.2-kDa active caltrin were absent. Trypsin inhibitory activity of the seminal secretion was reduced about 50% in castrated animals. Daily testosterone administration restored both the protein pattern and immunoreactivity of the seminal vesicle secretion, and, as expected, reversed the morphological alterations of the gland after 7 days of treatment. Trypsin--inhibitor effect of the secretion also returned to normal levels after fourteen days of testosterone administration. Data suggest that the synthesis and secretion of caltrin are testosterone-dependent processes.

Dynamics of the seminal vesicle epithelium

In newborn rodents, seminal vesicle epithelium (SVEP) cells display a poorly developed rough endoplasmic reticulum (RER) and Golgi complex, and they show no signs of secretion. From puberty onward, secretory material starts to appear, and the RER and Golgi complex progressively develop and reorganize until the adult ultrastructure is established around 40-60 days of age. Multivesicular bodies and lysosomes follow in this development but lysosomes evolve to lipofucsin granules with aging. The duration of the secretory cycle in SVEP cells is shorter than in other exocrine cells and the secretory protein pattern depends on the animal species, androgen status, and sexual activity. SVEP cells are also involved in endocytosis, which is coupled to exocytosis, and their endocytic pathway intersects the exocytic pathway in Golgi cisterns. The structure and function of SVEP cells depends mainly on testosterone, but other hormones and factors, such as the neuropeptide VIP, also influence their activity. Castration leads to programmed death and regression of SVEP cells to an extent that depends on the animal species. In addition, castration induces changes in the secretory protein pattern and delays its intracellular transport. Endocytic kinetics is also delayed following castration. Primary cultures of SVEP cells in a bicameral system are proposed as a model to investigate the activities of SVEP cells further.

Castration-resistant secretion in the hamster seminal vesicle does not depend on androgens

The secretory activity of seminal vesicles (SV) in the castrated hamster was studied by stereological analysis and biochemical approaches following treatment with cyproterone acetate (CPA) and adrenalectomy in order to investigate whether extra-testicular androgens are responsible for castration-resistant protein secretion. Treatment of castrated animals with CPA decreased the size of secretory granules and increased the number of apical granules, though neither the absolute nor the relative volume of all the components analysed was changed. In addition, CPA-treatment increased the amount of protein exocytosed by SV in castrated animals, though total protein synthesis remained unchanged. Adrenalectomy neither suppressed secretion nor induced any further ultrastructural changes in the SV epithelium. Our results demonstrate that secretory activity of the hamster SV following castration is not controlled by extra-testicular androgens and suggest that SV secretory proteins, which are heterogeneous with regard to their sensitivity to androgen withdrawal, might be regulated differentially by androgens.

Genital fibroblasts from normal individuals and patients with androgen insensitivity: demonstration of reduced or absent levels of a specific protein (Mr approximately 41K, pI approximately 6) in receptor negative cells

Genital fibroblasts were obtained from normal individuals and from patients with a variety of syndromes of defective androgenization (complete androgen insensitivity, partial androgen insensitivity, microgenitalia, hypospadias, infertility). Cells were labelled with [35S]methionine, and patterns of protein synthesis compared by two-dimensional gel electrophoresis, with isoelectrofocusing electrophoresis gels or non-equilibrated pH gradient electrophoresis (NEPHGE) gels as the first dimension. A protein (mol. wt approximately 41K, pI approximately 6) was found on NEPHGE gels to be reduced or absent in fibroblasts in which androgen receptor levels were abnormal. The protein was unaltered by prior incubation with 1-100 nM dihydrotestosterone for 48 h, and was present in cells both from normal controls, and from patients with abnormal sexual differentiation showing normal androgen receptor levels. The coincidence of low or absent 41K with low or absent androgen receptors suggested the possibility that it may constitute a steroid-binding moiety of the androgen receptor. To test this possibility cytosols from normal foreskins or normal cultured fibroblasts were adsorbed with testosterone-sepharose affinity resin to remove androgen receptors. Cytosols so treated showed levels of 41K on NEPHGE indistinguishable from those in untreated cytosols, or in cytosols treated with underivatized sepharose. We therefore conclude that the 41K protein, while an accurate marker of the presence or absence of androgen receptors over a range of clinical disorders, is neither an androgen-induced protein nor an androgen-binding protein.

Tissue distribution, developmental profile and hormonal regulation of androgen-responsive secretory proteins of rat seminal vesicles studied by immunocytochemistry

The seminal vesicles of the rat synthesise large amounts of androgen-regulated secretory proteins. Indirect immunofluorescence cytochemistry and immunoblotting with monospecific polyclonal antibodies against three of the major secretory proteins (II, S and F) have been used to investigate the tissue distribution, subcellular localisation, androgen-regulation and developmental profile of secretory protein synthesis. There was no evidence for regional specialisation of the seminal vesicle epithelium; every epithelial cell synthesizes all three proteins via a classical secretory involving storage in secretory vesicles. Proteins S and II are contained within the same secretory vesicles. The time course of deinduction of proteins S and F after castration and their reinduction by testosterone closely followed that for their specific mRNAs described previously. During development, proteins S and F first appear between 10 and 15 days after birth. A protein immunologically related to seminal vesicle protein II is present in the lateral and dorsal lobes of the prostatic complex.

Identification and androgen-dependence of proteins in the mouse vas deferens

Proteins from 'luminal fluid' or from a homogenate of whole vas deferens were analysed by polyacrylamide gel electrophoresis under denaturing conditions. Four major bands with apparent molecular weights of 34.5, 36, 38 and 180 Kilodaltons (K) were observed in homogenates. In 'luminal fluid' the same protein pattern was observed except that 38 K band was missing. These four major bands probably originated from the vas deferens as they were not detected in plasma and were still present after ligation between the epididymis and vas deferens. After castration, there was a specific reduction of the 34.5 K MW protein band in both homogenate and 'luminal fluid'. When the androgen-dependence of proteins was investigated using radioactive methionine, the protein spectra from normal and castrated males showed that about 10 polypeptides were differentially induced or repressed by androgens. The synthesis of some proteins (MW's 24, 36 and 180 K) was decreased by castration while the synthesis of several others (MW's between 27 and 82 K) was increased. Most of these androgen-dependent proteins were detectable at 10 days of age.

Immunoelectron microscopic evidence for different compartments in the secretory vacuoles of the rat seminal vesicles

Immunoelectron microscopy of the rat seminal vesicle was performed using specific antibodies to secretory proteins. Proteins were precipitated from rat seminal vesicle secretion and were separated by SDS-polyacrylamide gel electrophoresis. Among the great number of bands the two most prominent bands were selected and designated SVS II and IV. Their apparent molecular weights were 48 kDa and 16.5 kDa respectively. The bands were excised from the gels and used for antibody production in rabbits. The respective antisera were used for immunohistochemical studies both at the light and electron microscopic levels in the rat seminal vesicle and the different prostatic lobes in infantile, adult and castrated animals. A positive immunoreaction was observed in seminal vesicle and lateral prostatic epithelium of the intact adult rat, while it was lacking in prepubertal and castrated animals. The subcellular distribution of both proteins was clearly different: SVS II was exclusively confined to the electron dense core of the secretory vacuoles, while SVS IV was detected only in the clear halo surrounding the central granule. It is suggested that the spatial arrangement of both proteins in the seminal vesicle secretion vacuole reflects a particular functional significance of each of these proteins. These proteins may serve as a tool in the study of regulation of androgen-dependent protein synthesis.

Polymorphism of rat seminal vesicle secretory proteins: characterization of svp-1 and svp-2 and their identification with the major secretory proteins IV and V

The proteins secreted by the rat seminal vesicle can be separated into five denaturing conditions. Two polymorphic proteins, svp-1 and svp-2, also present in the mouse, are produced by the seminal vesicle as well, but the procedure used for their identification makes it impossible to ascertain whether they correspond to any of the major fractions mentioned above. We show here that, on the basis of molecular weight measurements and of amino acid composition determinations, svp-1 and RSV-V are indeed the same protein. We also show that svp-2 is strictly related to another major secretory protein, RSV-IV, whose amino acid composition is almost identical, but for a few amino acid residues, to that of svp-2. We thus conclude that the latter protein is a variant of RSV-IV that can be expressed only in rats homozygous for a given allele at the svp-2 locus. This paper thus brings together published information on the genetics of the loci coding for svp-1 and for svp-2 and on the molecular biology of RSV-IV and RSV-V and of their corresponding gene.

Effects of steroids on fibroblasts: identification of glucocorticoid-regulated proteins by two-dimensional gel electrophoresis

Fibroblasts cultured from normal human forearm or genital skin were exposed to dexamethasone (DM) 10(-9)-10(-7) M, deoxycorticosterone (DOC) 10(-6)M, or vehicle for 4-16 h and [35S]methionine-labelled proteins compared by two-dimensional gel electrophoresis. No effects on cell number or [35S]methionine incorporation were seen with either steroid, nor any effects of DOC on patterns of protein synthesis. In contrast, after 4 h incubation DM consistently (24/24 gels) caused increased abundance of a protein spot designated k (kappa; Mr approximately 41 000, pKi approximately 6.5). After 16 h steroid exposure, levels of protein kappa remained elevated; abundance of a second protein spot omega (omega; Mr approximately 42 000, pKi approximately 5.4) was consistently (8/8 gels) lower than in control fibroblasts. We interpret these data as evidence for glucocorticoid-specific effects on human skin fibroblasts, and that (within the pKi and molecular weight range studied) the observed changes in abundance of proteins kappa and omega constitute the human fibroblast glucocorticoid domain.

Isolation and culture of rat seminal vesicle epithelial cells. The use of the secretory protein SVS IV as a functional probe

A method for the isolation and culture of seminal vesicle epithelial cells obtained from control and androgen-primed sexually-immature, uncastrated rats is described. This method allows the establishment of monolayer cultures from aggregates of seminal vesicle epithelial cells isolated after trypsin and collagenase digestion. Phase contrast and transmission electron microscopic methods demonstrate that cell aggregates, after attaching to the substrate, establish within 48 h a colony-like, epithelial-like growth pattern. Immunofluorescent localization studies of SVS IV, an androgen-dependent secretory protein purified from rat seminal vesicle secretion, show that cultured seminal vesicle epithelial cells are immunoreactive. An electrophoretic analysis of [35S]methionine-labeled secretory proteins immunoprecipitated with rabbit anti-SVS IV serum demonstrate that, whereas SVS IV is newly-synthesized and accumulated in the medium of cultured seminal vesicle cells established from androgen primed rats, cultured cells from control rats appear to synthesize and accumulate SVS IV in a precursor form. Results of this work show that seminal vesicle epithelial cells in culture not only retain several structural features representative of the tissue but also serve as a potential system for the study of androgen action.

Isolation and characterisation of genes for androgen-responsive secretory proteins of rat seminal vesicles

Under the influence of testosterone, rat seminal vesicles synthesise large amounts of a tissue specific protein, S. Recombinant lambda clones have been isolated containing overlapping sequences covering a 27.5 kilo base region of the rat genome within which the gene for protein S is located. Recombinant plasmids bearing cDNA sequences for protein S were constructed in pBR328. One (pcS2) contains a 690 nucleotide insert and is probably full length. Detailed restriction maps of the S-gene are presented and the structure was confirmed by analysis of R-loops and heteroduplexes. The S-gene covers a 2 kbp region of the genome and consists of a 5' intron (490 bp) separating a leading exon (120 bp) containing the 5' untranslated region from a central exon (310 bp) containing most of the coding sequence and part of the 3' untranslated region. A larger intron (1100 bp) lies within the 3' untranslated region. The cloned gene is representative of the native gene but the S gene may be heterogeneous. Using pcS2, the hormonal control of S-specific mRNA was examined and a pronounced differential response to testosterone was observed.