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Identification of a non-mitogenic paracrine factor involved in mesenchymal-epithelial cell interactions between
Abstract:
Seminiferous peritubular cells have previously been shown to secrete a protein termed P-Mod-S which modulates the functions of Sertoli cells. The present study provides an initial characterization of P-Mod-S and examines the actions of P-Mod-S on Sertoli cells. Gel filtration chromatography demonstrates that P-Mod-S has an apparent molecular weight of 70 000 that could not be dissociated to a lower molecular weight form. A 40- to 90-fold purification of P-Mod-S was obtained with a predicted half maximal effective concentration for Sertoli cells of less than 10(-9) M. Through an analysis of the actions of P-Mod-S on Sertoli cells it is demonstrated that P-Mod-S stimulates the Sertoli cell to a greater extent than any single hormone or vitamin known to influence the cell. P-Mod-S maximally stimulates testicular transferrin and androgen-binding protein production by Sertoli cells, but does not stimulate levels of plasminogen activator activity. P-Mod-S also appears to induce the synthesis of several proteins that are not detected in control non-treated Sertoli cell cultures. One such protein whose synthesis was stimulated by P-Mod-S treatment of Sertoli cells was a component having a molecular mass of 20 kDa. This 20 kDa Sertoli cell-secreted protein was specifically immunoprecipitated with an antibody against an epididymal lactalbumin-like protein. This implies that P-Mod-S can induce Sertoli cells to synthesize and secrete a lactalbumin-like protein. P-Mod-S was found not to contain mitogenic activity. Data presented indicate that testicular peritubular cells synthesize and secrete a 70 kDa non mitogenic paracrine factor termed P-Mod-S which has a dramatic influence on Sertoli cell functions. Results are discussed with respect to modulation of epithelial (Sertoli) cell functions by components produced by mesenchymal (peritubular) cells.
Insights
Testicular peritubular cells secrete P-Mod-S, a 70 kDa protein that significantly influences Sertoli cell functions. This non-mitogenic factor stimulates key protein production and induces lactalbumin-like protein synthesis in Sertoli cells.
Area of Science:
- Reproductive biology
- Cell signaling
- Endocrinology
Background:
- Seminiferous peritubular cells secrete P-Mod-S, a protein modulating Sertoli cell functions.
- Understanding P-Mod-S's role is crucial for comprehending testicular cell interactions.
Purpose of the Study:
- Characterize P-Mod-S and investigate its effects on Sertoli cells.
- Determine P-Mod-S's molecular properties and biological activities.
Main Methods:
- Gel filtration chromatography for molecular weight determination.
- Sertoli cell cultures to assess protein production and secretion.
- Immunoprecipitation to identify specific protein induction.
Main Results:
- P-Mod-S purified with 40-90 fold enrichment, effective at <10(-9) M.
- P-Mod-S maximally stimulates transferrin and androgen-binding protein production.
- Induces synthesis of a 20 kDa lactalbumin-like protein; lacks mitogenic activity.
Conclusions:
- Testicular peritubular cells secrete a 70 kDa non-mitogenic paracrine factor, P-Mod-S.
- P-Mod-S profoundly influences Sertoli cell functions, including protein synthesis.
- Highlights mesenchymal-epithelial cell communication in the testis.