Activation of the transcription factor CREB by bFGF and IL-1b in Sertoli cells.

GALARDO MARÍA NOEL; MERONI SILVINA B; RIERA MARÍA FERNANDA; PELLIZZARI ELIANA H; CIGORRAGA SELVA B.

Lisboa

Congreso; 12th International Congress of Endocrinology.; 2004

FSH, bFGF and IL1b increase transferrin production and lactate dehydrogenase activity in Sertoli cells (SC). The genes encoding for these proteins have a CRE-like site in their promoters. The biological actions of FSH on CRE-regulated genes may be readily explained through the activation of the classical AMP/PKA pathway. However, even though bFGF and IL1b regulate transferrin and lactate dehydrogenase expression, they do not activate the cAMP/PKA pathway. At present, it is not known whether these hormones also activate CREB by using signaling pathways other than camp/PKA. The aim of this study was to analyze a possible CREB activation by bFGF and IL1b in SC. To clarife this point, 20-day-old  rat SC cultures were stimulated with FSH (100ng/ml), bFGF (30ng/ml) and IL-1b (50ng/ml) for 5 and 15 minutes and CREB phosphorylation (P-CREB) was determined by western-blot analysis. Results are expressed as fold-stimulation over basal. As expected, FSH treatment increased P-CREB levels, reaching maximum values after a 15-minute treatment (10.7±4.3) . The PKA inhibitor H89 (10mM) blocked FSH stimulation.  An increase in P-CREB levels with IL1b and bFGF treatments was also observed (6.4±1.9 and 6.9±2.0 respectively). The MEK inhibitors PD98059 (10 mM) and U0126 (1 mM), and the p38-MAPK inhibitor, SB203580 (2 mM), decresed bFGF and IL-1b activation of CREB respectively. These results show that activation of p42/p44-MAPK pathway by bFGF and p38-MAPK pathway by IL-1b converge in CREB activation and suggest that this activation may, at least in part, contribute to the regulation of CRE-regulated genes in SC.