Distinct roles for isoforms of the catalytic subunit of class-IA PI3K in the regulation of behaviour of murine embryonic stem cells.
Self-renewal of embryonic stem cells (ESCs) is essential for maintenance of pluripotency, which is defined as the ability to differentiate into any specialised cell type comprising the adult organism. Understanding the mechanisms that regulate ESC self-renewal and proliferation is required before ESCs can fulfil their potential in regenerative therapies, and murine ESCs (mESCs) have been widely used as a model. Members of the class-IA phosphoinositide 3-kinase (PI3K) family of lipid kinases regulate a variety of physiological responses, including cell migration, proliferation and survival. PI3Ks have been reported to regulate both proliferation and self-renewal of mESCs. Here we investigate the contribution of specific class-IA PI3K isoforms to the regulation of mESC fate using small-molecule inhibitors with selectivity for particular class-IA PI3K catalytic isoforms, and siRNA-mediated knockdown. Pharmacological inhibition or knockdown of p110beta promoted mESC differentiation, accompanied by a decrease in expression of Nanog. By comparison, pharmacological inhibition or siRNA-mediated knockdown of p110alpha had no effect on mESC self-renewal per se, but instead appeared to reduce proliferation, which was accompanied by inhibition of leukaemia inhibitory factor (LIF) and insulin-induced PI3K signalling. Our results suggest that PI3Ks contribute to the regulation of both mESC pluripotency and proliferation by differential coupling to selected p110 catalytic isoforms.
Kingham
Emmajayne
E
Department of Pharmacy and Pharmacology and The Centre for Regenerative Medicine, University of Bath, Claverton Down, Bath BA2 7AY, UK.
Welham
Melanie
M
D000818:Animals; D049109:Cell Proliferation; D058534:Class I Phosphatidylinositol 3-Kinases; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D000071317:Nanog Homeobox Protein; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D007527:Isoenzymes; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D021122:Protein Subunits; D034741:RNA, Small Interfering; D019869:Phosphatidylinositol 3-Kinases; C509622:1-phosphatidylinositol 3-kinase p110 subunit, mouse; D058534:Class I Phosphatidylinositol 3-Kinases