title: Embryonic Stem Cell Growth Factors Regulate eIF2α Phosphorylation.
abstract: Growth factors and transcription factors are well known to regulate pluripotent stem cells, but less is known about translational control in stem cells. Here, we use embryonic stem cells (ESCs) to investigate a connection between ESC growth factors and eIF2α-mediated translational control (eIF2α phosphorylation promotes protein expression from mRNAs with upstream open-reading frames, or uORFs). We find abundant phosphorylated P-eIF2α (P-eIF2α) in both pluripotent mouse and human ESCs, but little P-eIF2α in ESCs triggered to differentiate. We show that the growth factors LIF (leukemia inhibitory factor) and BMP4 (bone morphogenic protein 4) both maintain P-eIF2α in mESCs, but use distinct mechanisms: LIF inhibits an eIF2α phosphatase whereas BMP4 activates an eIF2α kinase. The mRNAs encoding the pluripotency factors Nanog and c-Myc possess uORFs while Oct4 mRNA does not. We find that salubrinal, a chemical that increases eIF2α phosphorylation, promotes Nanog and c-Myc expression, but not Oct4 expression. These experiments connect ESC growth factors to eIF2α phosphorylation and suggest a chemical substitute for LIF to enhance Nanog and c-Myc expression.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States of America; Department of Chemistry and Biochemistry, Washington and Lee University, Lexington, Virginia, 24450, United States of America.
authors.forename: Kyle
authors.initials: K
authors.lastname: Friend
authors.affiliation: Department of Chemistry and Biochemistry, Washington and Lee University, Lexington, Virginia, 24450, United States of America.
authors.forename: Hunter A
authors.initials: HA
authors.lastname: Brooks
authors.affiliation: The Morgridge Institute for Research, 309 North Orchard Street, Madison, Wisconsin, 53715, United States of America.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Propson
authors.affiliation: The Morgridge Institute for Research, 309 North Orchard Street, Madison, Wisconsin, 53715, United States of America; Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, 53706, United States of America.
authors.forename: James A
authors.initials: JA
authors.lastname: Thomson
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States of America; Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States of America.
authors.forename: Judith
authors.initials: J
authors.lastname: Kimble
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology*; D002460:Cell Line; D002934:Cinnamates / Q000494:pharmacology; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D000066449:Human Embryonic Stem Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D053605:Leukemia Inhibitory Factor / Q000494:pharmacology*; D051379:Mice; D008954:Models, Biological; D000066450:Mouse Embryonic Stem Cells / Q000187:drug effects / Q000378:metabolism*; D000071317:Nanog Homeobox Protein; D010766:Phosphorylation / Q000187:drug effects; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D055415:Bone Morphogenetic Protein 4; D002934:Cinnamates; D015852:Eukaryotic Initiation Factor-2; D039603:Eukaryotic Initiation Factor-4G; D018398:Homeodomain Proteins; D053605:Leukemia Inhibitory Factor; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D016271:Proto-Oncogene Proteins c-myc; C496827:salubrinal; D013890:Thiourea