Regulation of levels of specific Sertoli cell mRNAs by vitamin A.

The regulation of Sertoli cell transferrin and sulfated glycoprotein-2 (SGP-2) mRNA levels by vitamin A was studied in vitamin A deficient rats. Vitamin A deficiency differentially affected the levels of these mRNAs. Sertoli cells from vitamin A deficient rats contained 3-fold less transferrin mRNA and 1.8-fold more SGP-2 mRNA than Sertoli cells from normal rats. Vitamin A deficiency did not result in changes in the amount of transferrin mRNA per liver cell. When vitamin A deficient rats were fed a retinol supplemented diet, Sertoli cell transferrin and SGP-2 mRNA levels returned to normal. In contrast, dietary retinoic acid did not support recovery of the levels of the two mRNAs. The regulation of transferrin and SGP-2 mRNA levels was further examined in vitamin A deficient rats that had received subcapsular testicular injections of vitamin A and in vitamin A supplemented cultures of Sertoli cells from vitamin A deficient rats. Under these conditions, retinol and retinoic acid both stimulated transferrin mRNA levels but did not affect SGP-2 mRNA levels. Retinol did not inhibit the turnover of transferrin mRNA in Sertoli cell cultures suggesting that the stimulation of transferrin mRNA levels by retinol is due to increased transcription of the transferrin gene. A mathematical correlation between the Sertoli cell transferrin mRNA levels and the weight of the testes or the number of germinal cells was observed.