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Biomedical subjects

M Galdieri

Publications and source records attributed to M Galdieri.

At least 37 records · Page 2Linked to original sources
PubMed1993

Cellular retinoic-acid-binding-protein and retinol-binding-protein mRNA expression in the cells of the rat seminiferous tubules and their regulation by retinoids.

The levels of the mRNA corresponding to the intracellular binding proteins for retinoic acid and retinol (CRABP1 and CRBP1, respectively) were studied in primary cultures of somatic and germ cells of the rat seminiferous tubules. We show that the CRABP1 mRNA is expressed in Sertoli and germ cells and a single molecular species of mRNA is detected. CRBP1 mRNA is detected in Sertoli and peritubular cells. The regulation of the expression of both genes by retinoids was studied in Sertoli cells. CRABP1 mRNA levels are not affected by either retinoic acid or retinol, whereas both compounds positively regulate CRBP1 mRNA synthesis in a dose-dependent manner. A fivefold increase in CRBP1 mRNA levels was observed 32-48 h after addition of either agent. These results demonstrate that in Sertoli cells the expression of CRABP1 is not affected by retinoids, similar to the situation observed in vivo and in other in-vitro cultures. CRBP1-gene expression is, instead, induced and the variations in CRBP1-mRNA levels may regulate the intracellular concentrations of retinoids, as a response to changes in the vitamin-A nutritional status.

Animals↗
PubMed1991

Cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase activity in the somatic cells of the seminiferous tubules. I. Isoform analysis.

In this work firstly are reported the chromatographic analysis of cAMP dependent protein kinases present in the cytosols obtained from rat Sertoli cells and peritubular cells. In both cell types two different isoenzymes have been detected, one eluting at 40-80 mM KC1 (type I) and a second one eluting at 150-200 mM KC1 (type II). Only the type I was strongly stimulated by cAMP whereas the type II was slightly cAMP dependent both in the Sertoli cells and in the peritubular cells.

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PubMed1991

Cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase activity in the somatic cells of the seminiferous tubules. II. Effect of retinol.

The effect of retinol on cyclic AMP dependent protein kinase activity of Sertoli cells and peritubular cells isolated from prepubertal rats has been investigated. Treatments longer than six hours induced a significant inhibition of type I protein kinase activity of Sertoli cells without appreciable variation of type II protein kinase. Short time treatments with the vitamin did not affect the Sertoli cell protein kinase activity. The vitamin A addition did not induce any appreciable variation of peritubular cell protein kinase activity.

Animals↗
PubMed1989

Levels of binding proteins for retinoids in cultured Sertoli cells: effect of medium composition.

The levels of cellular retinol-binding protein (CRBP) and cellular retinoic acid-binding protein (CRABP) have been measured in Sertoli cells maintained under different cultural conditions. Sertoli cells were isolated from prepubertal rats and cultured in a chemically defined medium without or with follicle-stimulating hormone (FSH), insulin, retinol or testosterone added individually or in combinations. The additions were made at the beginning of the culture or 24 h before the cells were subjected to determinations of CRBP and CRABP by radioimmunoassay. No differences were observed either after 1 or 4 days of treatment. The results obtained indicated that the levels of the two retinoid-binding proteins were unchanged in Sertoli cells in response to hormone and/or retinol administration. To rule out the possibility that the Sertoli cells used in our study were unresponsive to the hormones, lactate production by the cells cultured in the presence of FSH or insulin was measured. The amount of lactate produced under hormonal stimulation was significantly higher than the amount produced in absence of the hormones, thus indicating the ability of our Sertoli cells to respond to the hormonal stimulation.

Animals↗
PubMed1989

Lonidamine effect on male rat germ cells.

Lonidamine, a dichlorinated derivative of indazole-3-carboxylic acid, has recently been indicated as an antiproliferative agent being able to reduce mitotic activity of tumor cells. We have evaluated lonidamine effect on proliferating, non tumor cells choosing as a model the male germ cells obtained from cultured seminiferous epithelium explants. The obtained germ cells are able to duplicate in vitro and we have found that lonidamine, at low doses, induces a significative inhibition of the incorporation of labelled thymidine into the duplicating germ cells. The effect seems to be specific for the germ cells since lonidamine does not affect duplicative ability of the somatic cells of the seminiferous tubules and of muscle fibroblasts.

Animals↗
PubMed1988

Detection of cellular retinol-binding protein messenger RNA in the somatic cells of the rat seminiferous tubules.

A cDNA clone coding for Cellular Retinol-Binding Protein (CRBP) was used as a probe to study the expression of the gene in the somatic cells of the seminiferous tubules (Sertoli and peritubular cells). In this paper we demonstrate that these cells are actively involved in the synthesis of the specific mRNA. In Sertoli cells the gene is modulated by the hormones effective in spermatogenesis, such as FSH and testosterone. Moreover, peritubular cells revealed an approximately two times higher concentration of CRBP steady-state mRNA levels when compared with Sertoli cells.

Animals↗
PubMed1987

Distribution and levels of cellular retinol- and cellular retinoic acid-binding protein in various types of rat testis cells.

The distribution and levels of cellular retinol-binding protein (CRBP) and cellular retinoic acid-binding protein (CRABP) were measured in rat testicular peritubular and Sertoli cells and in isolated rat pachytene spermatocytes and spermatids. Two Sertoli cell preparations, one containing some germ cells and another that had been osmotically shocked to destroy germ cells, were examined. CRBP and CRABP levels were measured by specific and sensitive radioimmunoassays. Testicular peritubular cell cytosol preparations were found to contain high levels of CRBP (1.48 +/- 0.87 microgram CRBP/mg protein) but CRABP could not be detected. The mean CRBP level in Sertoli cell preparations that contained some germ cells was 0.93 +/- 0.24 microgram CRBP/mg protein; this value was similar to the level of 1.11 +/- 0.20 microgram CRBP/mg protein measured for Sertoli cells free of germ cells. The level of CRABP found in Sertoli cell preparations containing germ cells (0.81 +/- 0.32 microgram CRABP/mg protein) was approximately five times greater than was observed in Sertoli cells free of germ cells (0.16 +/- 0.03 microgram CRABP/mg protein). CRBP and CRABP levels in cultured Sertoli cells were not affected by time in culture for up to five days of culture. Pachytene spermatocytes and spermatids were very enriched in CRABP (0.72 +/- 0.26 microgram CRABP/mg protein for spermatocytes and 0.65 +/- 0.21 microgram CRABP/ml protein for spermatids). A search for a high molecular weight retinol-binding protein did not demonstrate the existence of such a protein in Sertoli cell-conditioned medium. In summary, these studies provide quantitative information about the distribution of the cellular retinoid-binding proteins in the cell types that compose the rat testis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Sertoli cell membrane polypeptide composition is modulated by germ cells.

The polypeptide composition of Sertoli cell enriched cultures (SCEC) and Sertoli cell only cultures (SCOC) obtained after germ cell removal was investigated. Cells were labelled with [35S]methionine and analyzed by one and/or two-dimensional gel electrophoresis. The one-dimensional electrophoretic analysis of SCEC and SCOC particulate fraction did not show any appreciable difference between the two profiles. The more detailed two-dimensional electrophoretic analysis showed the appearance in SCOC of three polypeptides undetectable in SCEC. The molecular weight of these molecules ranged between 44 and 48 kDa. The effect of FSH on the Sertoli cell membrane composition was also investigated. No qualitative differences were detected, although the hormone increased many molecular species including the polypeptides appearing in SCOC. On the basis of these results, the hypothesis that germ cells influence Sertoli cell metabolic parameters is discussed.

Animals↗
PubMed1986

Calcium-, phospholipid-dependent protein kinase activity of cultured rat Sertoli cells and its modifications by vitamin A.

The activity of the calcium-, phospholipid-dependent protein kinase (PKc) was partially characterized in Sertoli cell cultures prepared from 20-day-old rats. The calcium dependency, the requirements for phosphatidylserine and diolein, as well as the Km for ATP and for the tumor promoter TPA, were determined in total cell extracts. The specific activity of PKc was almost 3-fold higher in the soluble than in the particulate fraction of Sertoli cells. Treatment of cultured Sertoli cells with retinol inhibited, within 1 h of treatment, both the soluble and the particulate fraction-associated PKc activity, with an IC50 of 0.1 microM. Partial inhibition of PKc activity was obtained treating Sertoli cell cultures with FSH, while testosterone was ineffective. However, both FSH and testosterone potentiated the inhibitory effect of retinol. Less differentiated Sertoli cells, obtained from 8-day-old rats, displayed higher PKc activity and a pattern of subcellular distribution of the enzyme opposite to that of Sertoli cells obtained from 20-day-old rats. These data suggest that the actual PKc activity of rat Sertoli cells be negatively regulated by retinol and, spontaneously, during the progression of Sertoli cell differentiation.

Animals↗
PubMed1984

Morphological and biochemical effects of lonidamine on cultured Sertoli cells.

Lonidamine, an antispermatogenic compound derivative of indazole-3-carboxylic acid, administered to rat Sertoli cells induced morphological changes of the cells which rapidly shrinked forming cytoplasmic projections. Some biochemical parameters of Sertoli cells measured after drug administration were their aromatizing ability, protein synthesis, and ribonucleic acid synthesis. The amount of estradiol produced by treated cells was significantly lower than the amount produced by control cells, whereas protein and ribonucleic acid synthesis were not affected by the drug. Our results demonstrate the change of a specific metabolic parameter of Sertoli cells induced by this antispermatogenic compound.

Animals↗
PubMed1983

Changes of Sertoli cell glycoproteins induced by removal of the associated germ cells.

Sertoli cell glycoproteins were studied in culture where these cells were in contact with germ cells (Sertoli cell enriched cultures, SCEC) and in pure Sertoli cell cultures. Sertoli cell only cultures (SCOC) were prepared by a short treatment of SCEC with hypotonic solution or by culturing seminiferous epithelium fragments from prenatally irradiated rats. After metabolic labeling with [3H]fucose. [14C]N-acetylglucosamine or [3H]leucine, SCEC and SCOC particulate fractions (105 000 g pellet) were analyzed by one-dimensional slab gel electrophoresis and fluorography. The comparison of the electrophoretic patterns obtained, demonstrated that a glycoprotein of MW 48 000, undetectable in SCEC, was present in SCOC after labelling with both sugar precursors. The MW 48 000 glycoprotein was also present in the electrophoretic profile of particulate fraction from [3H]fucos-labelled Sertoli cell cultures from prenatally irradiated rat. Such difference was not observed after labelling with [3H]leucine; in this experimental condition a MW 48 000 band was present in the electrophoretic profile of polypeptides from SCEC as well from SCOC. The synthesis of this glycoprotein represented a specific and stable cell response, since it occurred only a few hours after germ cell removal, and it was still detectable 3 days later. FSH stimulation did not influence the synthesis of the MW 48 000 glycoprotein, whereas it increased the synthesis of high MW glycoproteins. The hypothesis is discussed that the appearance of a new glycoprotein when Sertoli cells have lost their contact with germ cells could represent a product of glycosylation of preexisting molecules and their possible location in the Sertoli cell membrane. The results presented here provide additional evidence that Sertoli cell functions may be dependent on the association with the germ cell.

Animals↗
PubMed1983

Evidence of protein secretion by cultured pachytene spermatocytes.

Pachytene spermatocytes isolated from immature rat testis were cultured for 6 h in the presence of [35S]methionine and the macromolecules present in the culture medium were analyzed by one-dimensional and two-dimensional gel electrophoresis. The electrophoretic profiles obtained showed a limited number of polypeptides, some of them consisting of families of spots with the same molecular weight but a different isoelectric point. The reproducibility of the results and the unaltered metabolic activity of the cells during culture time, indicate that the macromolecules present in the medium do not represent degradative products of the cells. Part of the detected macromolecules are considered secreted proteins since the addition of monensin to the cells induces their disappearance from the culture medium.

Animals↗
PubMed1983

Retinol increases synthesis and secretion of Sertoli cell mannose-containing glycoproteins.

Sertoli cell isolated from prepuberal rats were cultured in a chemically defined medium in the presence or in the absence or retinol. In the two experimental conditions the incorporation of 3H-mannose into cellular glycoproteins was measured. The results obtained demonstrated a 3 fold increase of mannose incorporation into cellular glycoproteins after retinol addition without any qualitative variation of their electrophoretic profile. Sertoli cell secretory activity increased of approximately 50% after retinol administration; the electrophoretic analysis showed that two of the secretory products were selectively enhanced by the vitamin addition.

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