title: Glycogen synthase kinase-3 inhibition enhances translation of pluripotency-associated transcription factors to contribute to maintenance of mouse embryonic stem cell self-renewal.
abstract: Maintenance of embryonic stem cell (ESC) self-renewal and pluripotency are controlled by extrinsic factors, molecular signaling pathways and transcriptional regulators. While many of the key players have been studied in depth, how the molecular signals interact with transcription factors of the pluripotency network to regulate their action remains less well understood. Inhibition of glycogen synthase kinase 3 (Gsk-3) has been implicated in the maintenance of mouse ESC pluripotency, although there is contradictory data on its role, with enhancement of cell survival and metabolism, stabilisation of c-Myc and activation of Wnt signalling proposed as potential mechanisms. We have discovered that suppression of Gsk-3 activity leads to enhanced protein levels of key transcriptional regulators of the pluripotency network, notably Nanog, Tbx3 and c-Myc. Protein stability was unchanged following Gsk-3 inhibition, although interestingly, Nanog and Tbx3 proteins were found to have half-lives of 1-3 h, while that of Oct4 protein was longer, at 6 h. We demonstrate that the effects on protein levels seen following inhibition of Gsk-3 are due to both enhanced de novo synthesis of Nanog protein and increases in the proportion of Nanog and Tbx3 RNAs bound to polysomes, findings consistent with Gsk-3 regulating translation of these factors. These effects were not due to changes in regulators of general translation initiation machinery nor mediated via the 5' or 3' UTR sequences of Nanog alone. The data we present provide both new conceptual insight into the mechanisms regulated by Gsk-3 that may contribute to ESC self-renewal and, importantly, establish control of protein translation as an additional mechanism involved in modulation of ESC pluripotency.
authors.affiliation: Centre for Regenerative Medicine and Department of Pharmacy & Pharmacology, University of Bath, Bath, United Kingdom.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sanchez-Ripoll
authors.forename: Heather K
authors.initials: HK
authors.lastname: Bone
authors.forename: Tom
authors.initials: T
authors.lastname: Owen
authors.forename: Ana M V
authors.initials: AM
authors.lastname: Guedes
authors.forename: Elsa
authors.initials: E
authors.lastname: Abranches
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kumpfmueller
authors.forename: Ruth V
authors.initials: RV
authors.lastname: Spriggs
authors.forename: Domingos
authors.initials: D
authors.lastname: Henrique
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Welham
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D051379:Mice; D000071317:Nanog Homeobox Protein; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D047428:Protein Kinase Inhibitors; D014157:Transcription Factors; D038362:Glycogen Synthase Kinase 3