Melatonin signaling pathways implicated in metabolic processes in human granulosa cells (KGN)

Female reproduction depends on the metabolic status especially during the period of folliculogenesis. Even though it is believed that melatonin can improve oocyte competence, there is still limited knowledge of how it can modulate metabolic processes during folliculogenesis, and of which signaling pathways are involved in regulating gene expression. To investigate the effects of melatonin on metabolic signals during the antral stage of follicular development, human granulosa-like tumour cells (KGN) were treated with melatonin or forskolin and gene expression was analyzed with RNA seq technology. Following appropriate normalization and the application of a fold change cut-off of 1.5 (FC 1.5, P = 0.05), 1,009 and 922 genes were identified as differentially expressed in response to melatonin and forskolin, respectively. Analysis of major upstream regulators suggested that melatonin may activate PKB/mTOR signaling pathways to program the metabolism of KGN cells to support slower growth and differentiation and to prevent follicular atresia. Similarly, PKA activation through stimulation of cAMP synthesis with FSK seemed to exert the same effects as melatonin in reducing follicular growth and regulating differentiation. This study suggests that it is possible that melatonin acts through PKA and PKB simultaneously in human granulosa cells to prevent follicular atresia and early luteinisation at the antral stage. Overall design: Granulosa cells treated with melatonin or FSK to activate signaling pathways with gene functional analysis. RNA was pooled from four replicates per sample condition.