Exit from Pluripotency Is Gated by Intracellular Redistribution of the bHLH Transcription Factor Tfe3

Abstract

SummaryFactors that sustain self-renewal of mouse embryonic stem cells (ESCs) are well described. In contrast, the machinery regulating exit from pluripotency is ill defined. In a large-scale small interfering RNA (siRNA) screen, we found that knockdown of the tumor suppressors Folliculin (Flcn) and Tsc2 prevent ESC commitment. Tsc2 lies upstream of mammalian target of rapamycin (mTOR), whereas Flcn acts downstream and in parallel. Flcn with its interaction partners Fnip1 and Fnip2 drives differentiation by restricting nuclear localization and activity of the bHLH transcription factor Tfe3. Conversely, enforced nuclear Tfe3 enables ESCs to withstand differentiation conditions. Genome-wide location and functional analyses showed that Tfe3 directly integrates into the pluripotency circuitry through transcriptional regulation of Esrrb. These findings identify a cell-intrinsic rheostat for destabilizing ground-state pluripotency to allow lineage commitment. Congruently, stage-specific subcellular relocalization of Tfe3 suggests that Flcn-Fnip1/2 contributes to developmental progression of the pluripotent epiblast in vivo.

Negative feedback via RSK modulates Erk‐dependent progression from naïve pluripotency

“…This assay for capacity to resume self‐renewal is a stringent and quantitative measure of persistent ES cell status 15. RSK deleted mutant cells displayed a marked reduction in the ability to form alkaline‐positive (AP) undifferentiated colonies (Fig 3C), correlating with the rate of RGd2 downregulation (Figs 2B and 3A).…”

“…Upon withdrawal from 2iLIF, ES cells enter the pathway to multilineage differentiation while continuing to proliferate 15, 16, 17. This transition can occur in defined media without exogenous inductive signals, implying that it is intrinsically driven and that self‐renewal entails active suppression of the effector pathways for developmental progression 18.…”

“…Conversely, LIF acts by boosting expression of members of the network 22, 23, 24. Genetic perturbations have established that ERK1/2 signalling downstream of fibroblast growth factor 4 (FGF) is important for timely and efficient exit from the naïve state and subsequent commitment 15, 25, 26, 27, 28, 29, 30, 31. Consistent with this, inhibition of either FGF receptor or the MEK/ERK1/2 pathway markedly impedes ES cell differentiation 6, 32, 33.…”

Serum Inter-α-inhibitor Activates the Yes Tyrosine Kinase and YAP/TEAD Transcriptional Complex in Mouse Embryonic Stem Cells

“…Some of these transcriptional factors have been designated as stem-cell markers, e.g. Nanog, Oct3/4, Tfe3, Sox2, and Esrrb (10). In addition, the YAP-TEAD transcription factor complex has been reported to be important for mES cell selfrenewal and maintenance of pluripotency (11,12).…”

Metabolic regulator Fnip1 is crucial for iNKT lymphocyte development

“…growth, by phosphorylating and activating TSC2 (25), and by phosphorylating and inactivating Raptor (26). In a recent study, the Folliculin-Fnip1/2 complex was also found to stimulate embryonic stem cell differentiation by limiting access of Tfe3 into the nucleus, thereby allowing efficient exit from naive pluripotency (27). These studies suggest that Folliculin, Fnip1, and Fnip2 may act to modulate AMPK and mTOR activities during cellular differentiation.…”