Wnt/β-catenin/CBP signaling maintains long-term murine embryonic stem cell pluripotency

Abstract

Embryonic stem cells (ESCs) represent an important research tool and a potential resource for regenerative medicine. Generally, ESCs are cocultured with a supportive feeder cell layer of murine embryonic fibroblasts, which maintain the ESCs' capacity for selfrenewal and block spontaneous differentiation. These cumbersome conditions, as well as the risk of xenobiotic contamination of human ESCs grown on murine embryonic fibroblasts, make it a priority to develop chemically defined methods that can be safely used for the expansion of ESCs. Using a high-throughput, cellbased assay, we identified the small molecule IQ-1 that allows for the Wnt/␤-catenin-driven long-term expansion of mouse ESCs and prevents spontaneous differentiation. We demonstrate that IQ-1, by targeting the PR72/130 subunit of the serine/threonine phosphatase PP2A, prevents ␤-catenin from switching coactivator usage from CBP to p300. The increase in ␤-catenin/CBP-mediated transcription at the expense of ␤-catenin/p300-mediated transcription is critical for the maintenance of murine stem cell pluripotency. p300 ͉ PP2A ͉ Wnt signaling ͉ Nkd ͉ small molecule

The Calcineurin Variant CnAβ1 Controls Mouse Embryonic Stem Cell Differentiation by Directing mTORC2 Membrane Localization and Activation

“…This differential role might be associated to the regulation of AKT by different complexes (Guertin et al, 2006). Similar results have been described for β-catenin in mESC, where it has opposite effects depending on the complex it binds to (Miyabayashi et al, 2007). In this regard, we have not observed any contribution to pluripotency maintenance by CnAβ1, whereas we found a significant downregulation of ESC differentiation towards the mesoderm lineage after CnAβ1 depletion.…”

Engineering integrin signaling for promoting embryonic stem cell self-renewal in a precisely defined niche

“…; 76.3 AE 1.33%) was significantly lower than those of ESCs cultured in a 2D microenvironment with (84.5 AE 6.95%) or without (84.4 AE 6.95%) a MEF feeder layer. Thus, these studies showed that a synthetic 3D For identifying signal proteins regulated by downstream signaling derived from combinatorial activation of each integrin heterodimer, we investigated transcription and translation of Stat3 [34,35], b-catenin [36,37], Smad 1/5/8 [38] and Akt1 [39,40] genes and proteins, which have been reported as key signal molecules supporting stem cell self-renewal. In the case of Stat3 activated by LIF ( Supplementary Fig.…”

Chemical Biology of Pluripotent Stem Cells: Focus on Cardiomyogenesis

“…The mechanism of action was found to be independent of known self-renewal pathways thought to be essential (BMP4/Smad-Id [19], Wnt/B-catenin [20], LIF/STAT3 [21]). Instead, pluripotin was characterized as a dual inhibitor of extracellular signalregulated kinase-1 (ERK1) and RasGAP, two differentiation-inducing proteins.…”

“…This hypothesis is supported by a study by Ying et al [25], in which a combination of glycogen synthase kinase-3 (GSK-3) inhibitor, CHIR99021 and mitogen-activated protein kinase (MEK) inhibitor, PD0325901, could maintain long-term self-renewal of mESCs in the absence of exogenous cytokines [25]. Other small molecules which has been used to maintain mouse ES cells in pluripotent state include PD98059, a MEK inhibitor, 6-Bromoindirubin-3'-oxime (BIO), another GSK-3 inhibitor/Wnt signaling activator, and IQ-1, a modulator of Wnt/CBP signalling (Table 1) [20]. In addition to synthetic small molecules, certain physiological small molecules are capable of enhancing ES self-renewal.…”