title: Genome-wide gain-of-function screen identifies novel regulators of pluripotency.
abstract: Pluripotent stem cells are characterized by the capacity to self-renew and to differentiate into all the cell types of the body. To identify novel regulators of pluripotency, we screened cDNA libraries (>30,000 clones) in P19 embryonal carcinoma cells for factors that modulate the expression of a luciferase reporter driven by the promoter of the pluripotency master regulator Nanog. Ninety confirmed hits activated the reporter and 14 confirmed hits inhibited the reporter by more than two-fold. The identified hits were evaluated by gain- and loss-of-functions approaches. The reporter-activating hits Timp2, Hig2, and Mki67ip promoted embryonic stem (ES) cell self-renewal when episomally overexpressed in ES cells, whereas the reporter-inhibiting hits PU.1/Spi1, Prkaca, and Jun induced differentiation of ES cells. Conversely, the knockdown of the activating hits Timp2, Mki67ip, Esrrg, and Dusp7 in ES cells induced differentiation, whereas the knockdown of the reporter-inhibiting hit PU.1/Spi1 led to inhibition of differentiation. One of the novel hits, the RNA-binding protein Mki67ip was further characterized, and found to be overexpressed in ES cells and in early development and downregulated during differentiation. The knockdown of Mki67ip led to the differentiation of ES cells, decreased growth rate, reduction in pluripotency markers, and induction of lineage-specific markers. In addition, colocalization and coimmunoprecipitation experiments suggest that Mki67ip promotes ES cell self-renewal via a mechanism involving nucleophosmin, a multifunctional nucleolar protein upregulated in stem cells and cancer.
authors.affiliation: Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: Ramzey
authors.initials: R
authors.lastname: Abujarour
authors.forename: Jem
authors.initials: J
authors.lastname: Efe
authors.forename: Sheng
authors.initials: S
authors.lastname: Ding
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D045744:Cell Line, Tumor; D019070:Cell Lineage / Q000235:genetics*; D049109:Cell Proliferation; D054278:Embryonal Carcinoma Stem Cells / Q000378:metabolism* / Q000473:pathology; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D000071317:Nanog Homeobox Protein; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D000090243:Nucleophosmin; D020411:Oligonucleotide Array Sequence Analysis; D039904:Pluripotent Stem Cells / Q000378:metabolism* / Q000473:pathology; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D016601:RNA-Binding Proteins; D013997:Time Factors; D014162:Transfection
chemical_list: D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; C486780:NANOG protein, human; C431942:NIFK protein, mouse; C000716967:NPM1 protein, human; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D000090243:Nucleophosmin