TG-interacting factor1 (Tgif1) maintains the identity of mouse ES cells by counterbalancing the expression of ES cell core factors

TG-interacting factor1 (Tgif1) is well-known as a transcriptional repressor in transforming growth factor beta (TGFβ) signaling pathway. Target mapping of ES cell core factors in mouse embryonic stem (ES) cells revealed that Tgif1 is occupied by Oct4 and Nanog. Moreover, recent interactome study of mouse gene regulatory regions showed a preferential regulation of Tgif1 by mouse ES cell specific enhancers. However, the detailed role and mode of actions of Tgif1 in stem cell maintenance and development remains elusive. We show that Tgif1 is indispensable for self-renewal and pluripotency of mouse embryonic stem (ES) cells. Aberrant expression of Tgif1 promotes differentiation of ES cells even in the presence of LIF in part by deregulation of pluripotency factors. Intriguingly, we find that Tgif1 level is a critical factor to determine specific lineage commitment in a dosage-dependent manner. We further show that Tgif1 interacts with ES cell core factors and co-localizes at their binding sites, which eventually restricts expression of ES cell core factors including Oct4, Sox2, and Nanog. Taken together, we provide new insights into the roles of Tgif1 in maintenance as well as differentiation of ES cells.