Regulation of embryonic stem cell self-renewal by phosphoinositide 3-kinase-dependent signaling

Paling, N.R.D., Wheadon, H. , Bone, H.K. and Welham, M.J. (2004) Regulation of embryonic stem cell self-renewal by phosphoinositide 3-kinase-dependent signaling. Journal of Biological Chemistry, 279(46), pp. 48063-48070. (doi: 10.1074/jbc.M406467200)

Abstract

The maintenance of murine embryonic stem (ES) cell self-renewal is regulated by leukemia inhibitory factor (LIF)-dependent activation of signal transducer and activator of transcription 3 (STAT3) and LIF-independent mechanisms including Nanog, BMP2/4, and Wnt signaling. Here we demonstrate a previously undescribed role for phosphoinositide 3-kinases (PI3Ks) in regulation of murine ES cell self-renewal. Treatment with the reversible PI3K inhibitor, LY294002, or more specific inhibition of class IA PI3K via regulated expression of dominant negative Δp85, led to a reduction in the ability of LIF to maintain self-renewal, with cells concomitantly adopting a differentiated morphology. Inhibition of PI3Ks reduced basal and LIF-stimulated phosphorylation of PKB/Akt, GSK3α/β, and S6 proteins. Importantly, LY294002 and Δp85 expression had no effect on LIF-induced phosphorylation of STAT3 at Tyr705, but did augment LIF-induced phosphorylation of ERKs in both short and long term incubations. Subsequently, we demonstrate that inhibition of MAP-Erk kinases (MEKs) reverses the effects of PI3K inhibition on self-renewal in a time- and dose-dependent manner, suggesting that the elevated ERK activity observed upon PI3K inhibition contributes to the functional response we observe. Surprisingly, upon long term inhibition of PI3Ks we observed a reduction in phosphorylation of β-catenin, the target of GSK-3 action in the canonical Wnt pathway, although no consistent alterations in cytosolic levels of β-catenin were observed, indicating this pathway is not playing a major role downstream of PI3Ks. Our studies support a role for PI3Ks in regulation of self-renewal and increase our understanding of the molecular signaling components involved in regulation of stem cell fate.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wheadon, Professor Helen
• Authors: Paling, N.R.D., Wheadon, H., Bone, H.K., and Welham, M.J.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Journal Name: Journal of Biological Chemistry
• Journal Abbr.: J Biol Chem.
• Publisher: American Society for Biochemistry and Molecular Biology, Inc.
• ISSN: 0021-9258
• ISSN (Online): 1083-351X
• Published Online: 24 August 2004