Regulation of Nanog expression by phosphoinositide 3-kinase-dependent signaling in murine embryonic stem cells.
Embryonic stem (ES) cell pluripotency is regulated by a combination of extrinsic and intrinsic factors. Previously we have demonstrated that phosphoinositide 3-kinase (PI3K)-dependent signaling is required for efficient self-renewal of murine ES cells. In the study presented here, we have investigated the downstream molecular mechanisms that contribute to the ability of PI3Ks to regulate pluripotency. We show that inhibition of PI3K activity with either pharmacological or genetic tools results in decreased expression of RNA for the homeodomain transcription factor Nanog and decreased Nanog protein levels. Inhibition of glycogen synthase kinase 3 (GSK-3) activity by PI3Ks plays a key role in regulation of Nanog expression, because blockade of GSK-3 activity effectively reversed the effects of PI3K inhibition on Nanog RNA, and protein expression and self-renewal under these circumstances were restored. Furthermore, GSK-3 mutants mimicked the effects of PI3K or GSK-3 inhibition on Nanog expression. Importantly, expression of an inducible form of Nanog prevented the loss of self-renewal observed upon inhibition of PI3Ks, supporting a functional relationship between PI3Ks and Nanog expression. In addition, expression of a number of putative Nanog target genes was sensitive to PI3K inhibition. Thus, the new evidence provided in this study shows that PI3K-dependent regulation of ES cell self-renewal is mediated, at least in part, by the ability of PI3K signaling to maintain Nanog expression. Regulation of GSK-3 activity by PI3Ks appears to play a key role in this process.
Storm
Mike P
MP
Department of Pharmacy and Pharmacology and Centre for Regenerative Medicine, The University of Bath, Bath BA2 7AY, United Kingdom.
Bone
Heather K
HK
Beck
Craig G
CG
Bourillot
Pierre-Yves
PY
Schreiber
Valerie
V
Damiano
Teresa
T
Nelson
Adam
A
Savatier
Pierre
P
Welham
Melanie J
MJ
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics*; D053595:Embryonic Stem Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D000071317:Nanog Homeobox Protein; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D039904:Pluripotent Stem Cells; D015398:Signal Transduction
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D038362:Glycogen Synthase Kinase 3; D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; C475540:Nanog protein, mouse