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Results for “SERTOLI CELLS”

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PubMed1990

Germ cell regulation of Sertoli cell transferrin mRNA levels.

Sertoli cells cultured in the presence of germ cells responded by increasing the level of transferrin mRNA 3-fold as determined by solution hybridization and Northern blot analysis. In contrast, the steady state levels of other mRNAs, including sulfated glycoprotein 1 (SGP-1), sulfated glycoprotein 2 (SGP-2), transferrin receptor, regulatory subunit of cAMP dependent protein kinase, and ferritin light chain, were not influenced by coculture with germ cells. The transferrin mRNA stimulatory activity was found in conditioned medium from germ cells but was not associated with germ cell membrane components. The activity was abolished by treatment of the medium with trypsin. Partial characterization and isolation of the protein(s) from conditioned medium indicated that it has an apparent mol wt between 10 and 30 K. Studies using inhibitors of protein and nucleic acid synthesis indicated that the stimulation of transferrin mRNA by germ cell conditioned medium required both transcription and translation. Sertoli cell enriched (germ cell depleted) testes were obtained from male offspring of pregnant females irradiated at the 19th day of gestation. Testicular transferrin mRNA levels from irradiated rats decreased in comparison to levels in the normal rat, whereas SGP-2 mRNA levels were unchanged. These studies demonstrate that germ cell secretions may interact with Sertoli cells to specifically increase the level of transferrin mRNA and that this interaction may be a mechanism by which germ cells regulate the flow of iron across the seminiferous epithelium.

Animals↗
PubMed1987

Germ cell binding to rat Sertoli cells in vitro.

The interaction between male germ cells and Sertoli cells was studied in vitro by co-incubation experiments using isolated rat germ cells and primary cultures of Sertoli cells made germ cell-free by the differential sensitivity of germ cells to hypotonic shock. The germ cell/Sertoli cell interaction was examined morphologically with phase-contrast and scanning electron microscopy and then quantified by measuring radioactivity bound to Sertoli cell cultures after co-incubation with added [3H]leucine-labeled germ cells. Germ cell binding to Sertoli cell cultures was the result of specific adhesion between these two cell types, and several features of this specific adhesion were observed. First, germ cells adhered to Sertoli cell cultures under conditions during which spleen cells and red blood cells did not. Second, germ cells had a greater affinity for Sertoli cell cultures than they had for cultures of testicular peritubular cells or cerebellar astrocytes. Third, germ cells fixed with paraformaldehyde adhered to live Sertoli cultures while similarly fixed spleen cells adhered less tightly. Neither live nor paraformaldehyde-fixed germ cells adhered to fixed Sertoli cell cultures. Fourth, germ cell binding to Sertoli cell cultures was not immediate but increased steadily and approached a maximum at 4 h of co-incubation. Saturation of germ cell binding to Sertoli cell cultures occurred when more than 4200 germ cells were added per mm2 of Sertoli cell culture surface. Finally, germ cell binding to Sertoli cell cultures was eliminated when co-incubation was performed on ice. Based on these observations, we concluded that germ cell adhesion to Sertoli cells was specific, temperature-dependent, and required a viable Sertoli cell but not necessarily a viable germ cell. These results have important implications for understanding the complex interaction between Sertoli cells and germ cells within the seminiferous tubule and in the design of future experiments probing details of this interaction.

Animals↗
PubMed1988

Purification of a paracrine factor, P-Mod-S, produced by testicular peritubular cells that modulates Sertoli cell function.

A testicular paracrine factor, P-Mod-S, was purified from conditioned medium obtained from serum-free cultures of peritubular cells. Stimulation of testicular transferrin production by cultured Sertoli cells was utilized as a bio-assay for P-Mod-S. A bioactive protein with an apparent molecular weight of 50,000 under physiological conditions was isolated by high pressure size exclusion chromatography. P-Mod-S was found to have an affinity for heparin and bound to a heparin affinity column. Two forms of P-Mod-S were purified with reverse-phase chromatography. The less hydrophobic form was referred to as P-Mod-S (A) and is a 56,000 molecular weight protein. The more hydrophobic form was referred to as P-Mod-S (B) and is a 59,000 molecular weight protein. Purification of P-Mod-S (A) and P-Mod-S (B) from peritubular cell-radiolabeled secreted proteins revealed that both proteins contain radioactivity. This result demonstrates active synthesis and secretion of P-Mod-S by peritubular cells. Although the amino acid composition of the two proteins indicates distinct differences in the content of several amino acids, the relationship of P-Mod-S (A) and P-Mod-S (B) is unknown at present. A greater than 1000-fold increase in the specific activity of P-Mod-S was achieved with the purification procedure utilized. P-Mod-S can account for essentially all the bioactivity present in crude peritubular cell-secreted protein preparations. The effects of the two forms of P-Mod-S on both transferrin and androgen-binding protein production by Sertoli cells was examined. Purified forms of P-Mod-S were found to have a greater effect on Sertoli cell function than any individual regulatory agent previously known to influence the cell, including follicle-stimulating hormone. The significance of peritubular cell-Sertoli cell interactions mediated via P-Mod-S to spermatogenesis and testicular function is discussed, as well as insight provided into general mesenchymal-epithelial cell interactions.

Amino Acids↗