title: Elevating the levels of Sox2 in embryonal carcinoma cells and embryonic stem cells inhibits the expression of Sox2:Oct-3/4 target genes.
abstract: Recent studies have identified large sets of genes in embryonic stem and embryonal carcinoma cells that are associated with the transcription factors Sox2 and Oct-3/4. Other studies have shown that Sox2 and Oct-3/4 work together cooperatively to stimulate the transcription of their own genes as well as a network of genes required for embryogenesis. Moreover, small changes in the levels of Sox2:Oct-3/4 target genes alter the fate of stem cells. Although positive feedforward and feedback loops have been proposed to explain the activation of these genes, little is known about the mechanisms that prevent their overexpression. Here, we demonstrate that elevating Sox2 levels inhibits the endogenous expression of five Sox2:Oct-3/4 target genes. In addition, we show that Sox2 repression is dependent on the binding sites for Sox2 and Oct-3/4. We also demonstrate that inhibition is dependent on the C-terminus of Sox2, which contains its transactivation domain. Finally, our studies argue that overexpression of neither Oct-3/4 nor Nanog broadly inhibits Sox2:Oct-3/4 target genes. Collectively, these studies provide new insights into the diversity of mechanisms that control Sox2:Oct-3/4 target genes and argue that Sox2 functions as a molecular rheostat for the control of a key transcriptional regulatory network.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Boer
authors.forename: Janel
authors.initials: J
authors.lastname: Kopp
authors.forename: Sunil
authors.initials: S
authors.lastname: Mallanna
authors.forename: Michelle
authors.initials: M
authors.lastname: Desler
authors.forename: Harini
authors.initials: H
authors.lastname: Chakravarthy
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Wilder
authors.forename: Cory
authors.initials: C
authors.lastname: Bernadt
authors.forename: Angie
authors.initials: A
authors.lastname: Rizzino
mesh_terms: D000818:Animals; D018236:Carcinoma, Embryonal; D002460:Cell Line; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D018398:Homeodomain Proteins / Q000378:metabolism; D051379:Mice; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3 / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D055748:SOXB1 Transcription Factors; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D050814:Octamer Transcription Factor-3; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse; D015534:Trans-Activators