Tumor necrosis factor- inhibits glutathione S-transferase- expression in cultured porcine Sertoli cells

Glutathione S-transferases (GSTs) are a family of soluble enzymes of detoxification that use reduced glutathione in conjugation and reduction reactions. Toxic electrophiles are substrates for the GSTs. GST is expressed at high levels in different tissues such as the testis. Among the different GSTs present in the testis, GST is specifically expressed in Leydig and Sertoli cells known to be under the control of hormonal and local regulatory factors. The present study investigated the regulatory action of tumor necrosis factor(TNF ) on basal and hormone (FSH and testosterone)-stimulated GST expression in cultured Sertoli cells. Treatment with TNF (0–20 ng/ml, 48 h) induced a decrease in basal GST mRNA levels in a dose-dependent manner (fivefold decrease; P<0·001). The maximal and half maximal effects were observed at 20 ng/ml and 7 ng/ml respectively. The inhibitory effect of TNF was also time-dependent with a maximal inhibitory effect (threefold decrease; P<0·001) observed at 48 h. The inhibitory effect of the cytokine was also observed on basal GST protein (28 kDa) levels. TNF also inhibited the hormone-stimulated GST expression in Sertoli cells. The treatment of cultured Sertoli cells with both FSH and TNF (100 ng/ml and 10 ng/ml respectively, 48 h) resulted in a complete suppression of the stimulatory action of FSH on GST mRNA levels. Similarly, in Sertoli cells treated with testosterone or its non-aromatizable metabolite dihydrotestosterone (100 ng/ml, 24 h), TNF reduced the hormone-stimulated GST mRNA and protein levels. TNF inhibited basal GST expression without affecting mRNA stability. Indeed, the decay curves (mRNA half-life time=18 h) for the GST basal mRNA levels in Sertoli cells was similar in the absence or presence of TNF (10 ng/ml, 48 h). Testosterone increased GST mRNA without affecting the enzyme mRNA stability. TNF antagonized the androgen-stimulated GST mRNA levels without affecting the enzyme mRNA stability, suggesting that the interaction between the androgen and the cytokine is mostly exerted at a transcriptional level. FSH increased GST mRNA levels through an increase in mRNA stability (increased mRNA half-life times to 119 h). TNF antagonized the stimulatory effect of FSH on GST mRNA levels by antagonizing the stabilizing effect exerted by the hormone on GST mRNA. Together, these results suggest that the increase in the cytokine levels within the testis would alter the detoxification processes against genotoxic products during spermatogenesis. Journal of Endocrinology (2002) 175, 803–812