Regulation of glypican‐1, syndecan‐1 and syndecan‐4 mRNAs expression by follicle‐stimulating hormone, cAMP increase and calcium influx during rat Sertoli cell development

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Abstract
In seminiferous tubules, Sertoli cells provide structural and nutritional support for the developing germinal cells. Cell‐ to‐cell signaling and cell adhesion require proteoglycans expressed at the cell membrane. A preliminary biochemical and structural approach indicated that cell surface proteoglycans are mostly heparan sulfate proteoglycans (HSPG). Glypican‐1, syndecans‐1 and ‐4 were identified using a molecular approach. Their differential regulation was demonstrated in immature rat Sertoli cells. Follicle‐stimulating hormone (FSH) is the main regulator of Sertoli cell function. Signal transduction triggered by FSH involves both an increased intracellular cAMP synthesis and a calcium influx. This study demonstrates that FSH, through its second messengers (increase in intracellular cAMP and intracellular calcium), downregulated the glypican‐1 mRNA expression in Sertoli cells from 20‐day‐old rats. On the other hand, syndecan‐1 mRNA expression is not modulated by FSH as it would result from the antagonistic effects of increased intracellular cAMP and intracellular calcium levels. Finally, syndecan‐4 mRNA expression is not regulated by this pathway. The present study was extended during Sertoli cell development. Indeed, Sertoli cells undergo extensive changes during the postnatal period both in structure and function. These important transformations are critical for the establishment of spermatogenesis and development of the adult pattern of testicular function. Our data indicated that the regulation of HSPG mRNA expression is HSPG‐specific and depends on the Sertoli cell developmental stage.