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

doi:10.1073/pnas.0701331104

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

*Central R&D Laboratories, Asahi Kasei Corporation, Shizuoka 416-8501, Japan;
^‡Institute for Chemical Genomics, 600 Broadway, Suite 580, Seattle, WA 98122; and
^¶Department of Pharmacology, University of Washington, Seattle, WA 98195

Communicated by Edwin G. Krebs, University of Washington School of Medicine, Seattle, WA, February 14, 2007 (received for review October 23, 2006)

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 self-renewal 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, cell-based assay, we identified the small molecule IQ-1 that allows for the Wnt/β-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 β-catenin from switching coactivator usage from CBP to p300. The increase in β-catenin/CBP-mediated transcription at the expense of β-catenin/p300-mediated transcription is critical for the maintenance of murine stem cell pluripotency.

Footnotes

^†To whom correspondence may be addressed. E-mail: miyabayashi.tb{at}om.asahi-kasei.co.jp or michael.kahn{at}keck.usc.edu
Author contributions: T.M. and M.K. designed research; T.M., J.-L.T., M.Y., M.M., and C.N. performed research; T.M. and M.Y. contributed new reagents/analytic tools; T.M., J.-L.T., M.Y., M.M., and M.K. analyzed data; and T.M., J.-L.T., and M.K. wrote the paper.
↵ ^§Present address: Center for Stem Cell and Regenerative Medicine, Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0701331104/DC1.
Abbreviations:

ESC,

embryonic stem cell;

MEF,

murine embryonic fibroblast;

LIF,

leukemia inhibitory factor;

SSEA-1,

stage-specific embryonic antigen 1.