Melatonin regulates the phosphorylation of CREB in ovine pars tuberalis.

摘要: This study investigated whether melatonin could modulate the phosphorylation of calcium/cyclic AMP response-element binding-protein (CREB) within primary cell cultures ovine pars tuberalis (oPT) and distalis (oPD). Gel shift assays confirmed presence nuclear factors able to alter electrophoretic mobility a 32P-labelled CRE oligonucleotide. Two shifted bands were observed probably due monomer dimer binding CRE. Each band was supershifted by antisera directed against both CREB phosphorylated form (P-CREB), consistent with specific role proteins in transcriptional regulation. To physiological CREB, immunoreactivity for P-CREB followed oPT given different pharmacological treatments. Cells stimulated forskolin responded robust time- dose-dependent increase phospho-CREB (P-CREB-ir), confirming that activation this transcription factor occurred through cyclic AMP-PKA pathway. Maximal stimulation achieved 15 min persisted up 1 h. Treatment alone did not basal P-CREB-ir levels, yet inhibited forskolin-induced manner (IC50 between 10(-10) M 10(-8) when tested microM forskolin). In contrast, oPD, failed block forskolin-stimulated increases either content or intensity P-CREB-ir, action upon is tissue specific. These results demonstrate that, its inhibitory effect on PKA oPT, prevents reverses induced signal transduction Therefore has potential regulate gene expression acting factor. However, paper also shows 12-O-tetradecanoylphorbol-13-acetate (TPA) which activates PKC leads cells, suggesting involvement other pathways regulation these cells.