Elucidating the critical epigenetics events involved in differentiation and reprogramming of cells to primordial germ cells (PGCs) is among the interesting issues in stem cell research.
Here, I will talk about critical transcription factors and global hypomethylation in development of germ cells. Evidence strongly suggests that the earliest PGCs emerging in the E7.25 mouse embryo epiblast have a highly methylated genome, and high level of H3K9me2 in chromatin but during development, genome demethylated and patterns of histone codes changes dramatically.
We designed a polycistroniclentiviral vector and overexpressed Stella, Oct4 and Nanos2 simultaneously in transduced cells; Increasing level of Prdm14, Nanog and decreasing of G9a expression is an interesting finding which might be considered as a primary step of reprogramming toward germline progenitor cells, here we propose decreasing H3K9me2 level as a consequence of G9a down regulation is a critical step which facilitated transition to different stemness state through creating a new epigenetic memory for the early germ cells.
 
Keywords: Epigenetic, hypomethylation, Germ line Stem Cells, polycistroniclentiviral vector.