Molecular mechanism underlying Nelfa and Bcl2 mediated pluripotent to totipotent state conversion in embryonic stem cells

In mouse embryonic stem cells (ESCs), a minority of cell population displays totipotent features resembling 2-cell-stage embryos, as known as 2-cell-like (2C-like) cells. However, how ESCs transit into the 2C-like state remains largely unknown. Here we report that overexpression of negative elongation factor A (Nelfa) can partially activates the 2C-like state of ESCs in a naive ESCs maintenance medium, whereas its knockout could not block the activation of 2C-like genes, moreover, Nelfa knockout ESCs retain the capacity of germline transmission in chimeras. We also demonstrate that the co-overexpression of Nelfa and Bcl2 robustly activate the 2C-like transcripts of ESCs in naive culture condition as well as exhibit the ability of bi-potential cell fate, remarkably, we show that individual overexpression of Bcl2 successfully induces endogenous NELFA and the 2C-like state of ESCs even in Nelfa knockout ESCs. Notably, we also found that overexpression of Nelfa significantly increases the somatic cell reprogramming efficiency and exhibit a 2C-like state in induced pluripotent stem cells (iPSCs). In summary, the findings of our study provide insights into the mechanism underlying Nelfa and Bcl2 mediated totipotent state in mouse embryonic stem cells.