Insulin receptor substrate (IRS)-1 regulates murine embryonic stem (mES) cells self-renewal.
Mouse embryonic stem (mES) cells are pluripotent cells that can be propagated in vitro with leukemia inhibitory factor (LIF) and serum. Intracellular signaling by LIF is principally mediated by activation of STAT-3, although additional pathways for self-renewal have been described. Here, we identified a novel role for Insulin receptor substrate-1 (IRS-1) as a critical factor in mES cells self-renewal and differentiation. IRS-1 is expressed and tyrosyl phosphorylated during mES cells self-renewal. Differentiation of mES cells, by LIF withdrawal, is associated with a marked reduction in IRS-1 expression. Targeting of IRS-1 by si-IRS-1 results in a severe reduction of Oct-4 protein expression and alkaline phosphatase activity, markers of undifferentiated mES cells. IRS-1 targeting does not interfere with LIF-induced STAT-3 phosphorylation, but negatively affects protein kinase B (PKB/AKT) and glycogen synthase kinase-3 (GSK-3beta) phosphorylation, which are downstream effectors of the LIF-mediated PI3K signaling cascade. Targeting of IRS-1 also results in a marked down regulation of Id-1 and Id-2 proteins expression, which are important components for self-renewal of ES cells. Conversely, over expression of IRS-1 inhibits mES cell differentiation. Taken together, these results suggest that expression and activity of IRS-1 are critical to the maintenance of the self-renewal program in mES cells.
Rubin
Raphael
R
Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Arzumanyan
Alla
A
Soliera
Angela Rachele
AR
Ross
Brian
B
Peruzzi
Francesca
F
Prisco
Marco
M
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D055504:Insulin Receptor Substrate Proteins; D053605:Leukemia Inhibitory Factor / Q000378:metabolism; D051379:Mice; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
D015415:Biomarkers; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D050814:Octamer Transcription Factor-3; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D019869:Phosphatidylinositol 3-Kinases; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin