315 MELATONIN EFFECTS ON THE PROLIFERATION AND DIFFERENTIATION OF MOUSE EMBRYONIC STEM CELLS

Abstract

Mouse embryonic stem (ES) cells constitute a versatile biological system that can facilitate major advances in the fields of cell and developmental biology. Several studies have been performed to determine whether melatonin can affect ex vivo and in vitro proliferation and differentiation of stem cells (mesenchymal and neural stem cells derived human, rats, and mice), but its effect on ES cells is largely unknown. Thus, we further examined in this study the effects of melatonin at biological or pharmacological concentrations (100 or 200 μM) on the proliferation and differentiation of ES cells (ES-E14TG2a cells) using an in vitro culture system (n = 3) by Western blot analysis and real-time PCR. We found that melatonin at 100 and 200 μM resulted in cellular proliferation and phosphorylation of ERK and Akt, respectively. Melatonin treatment also increased Bcl-2 expression and suppressed Bax gene expression and increased phosphorylation of GSK α/β. The transcription factor Oct-4, which contains the POU (N-terminal to homeobox) domain, and the transcription factor Sox2, the zinc finger transcription factor Zfp206, and the zinc finger gene REX-1 (Znf42), which contain the high mobility group domain, are all important for cellular pluripotency and preimplantation development. In this study, melatonin (100 μM) treatment induced Oct-4 and REX-1 expression at day 1 but not at days 2 and 3. In addition, Sox2 and Zfp206 expressions were not altered following melatonin treatment. Taken together, these results suggest that melatonin may affect Akt phosphorylation and stem cell proliferation at biological or pharmacological concentrations.