Diverse Epigenetic Profile of Novel Human Embryonic Stem Cell Lines

Human embryonic stem cells (hESCs) are a promising model for studying mechanisms ofregulation of early development and differentiation. OCT4, NANOG, OCT4-related genes andsome others were recently described to be important in pluripotency maintenance. Lesser isknown about molecular mechanisms involved in their regulation. Apart from genetic regulationof gene expression epigenetic events, particularly methylation, play an important role in earlydevelopment. Using RT-PCR we studied the expression of pluripotency-related genes OCT4,NANOG, DPPA3, and DPPA5 during hESCs differentiation to embryoid bodies. Analysis ofmethylation profiles of promoter or putative regulatory regions of the indicated genesdemonstrated that expression of the pluripotency-maintaining genes correlated with theirmethylation status, whereas methylation of DPPA3 and DPPA5 varied between cell lines. Wepropose that DNA methylation underlies the developmental stage-specific mechanisms ofpluripotency-related genes expression and reactivation and may have an impact ondifferentiation potential of hESC lines.