Cover Story：Mouse embryonic stem cells (mESCs) are isolated from the inner cell mass (ICM) of the pre-implantation embryos. They can be maintained indefinitely as self-renewing populations while retaining the pluripotency to differentiate into the cells of all three primary germ layers when cultured under appropriate conditions in vitro. The transcriptional factor inhibitor of DNA binding 1 (Id1) can promote mESC self-renewal in serum condition without LIF. However, whether the other Id family members, such as Id2 and Id3, have similar function in mESCs is still unclear. In this study, we overexpressed Id2 and Id3 in 46C mESCs respectively, and found that both factors are able to support mESC self-renewal in the absence of LIF, while the self-renewal-promoting effect of Id2 is stronger than Id3. RNA-sequence approach revealed that Id2 is capable of upregulating c-Myc and n-Myc expression levels. Functional studies demonstrated that knockdown of c-Myc and n-Myc together could greatly reduce the function of Id2 in sustaining the undifferentiated state of mESCs, indicating that Myc family members have functional redundancy and can mediate the self-renewal-promoting effect of Id2 in mESCs. Our results will expand the current understanding of the pluripotency regulation network of embryonic stem cells.
