title: Proteomic analysis of Sox2-associated proteins during early stages of mouse embryonic stem cell differentiation identifies Sox21 as a novel regulator of stem cell fate.
abstract: Small increases in the levels of master regulators, such as Sox2, in embryonic stem cells (ESC) have been shown to promote their differentiation. However, the mechanism by which Sox2 controls the fate of ESC is poorly understood. In this study, we employed multidimensional protein identification technology and identified >60 nuclear proteins that associate with Sox2 early during ESC differentiation. Gene ontology analysis of Sox2-associated proteins indicates that they participate in a wide range of processes. Equally important, a significant number of the Sox2-associated proteins identified in this study have been shown previously to interact with Oct4, Nanog, Sall4, and Essrb. Moreover, we examined the impact of manipulating the expression of a Sox2-associated protein on the fate of ESC. Using ESC engineered for inducible expression of Sox21, we show that ectopic expression of Sox21 in ESC induces their differentiation into specific cell types, including those that express markers representative of neurectoderm and heart development. Collectively, these studies provide new insights into the range of molecular processes through which Sox2 is likely to influence the fate of ESC and provide further support for the conclusion that the expression of Sox proteins in ESC must be precisely regulated. Importantly, our studies also argue that Sox2, along with other pluripotency-associated transcription factors, is woven into highly interconnected regulatory networks that function at several levels to control the fate of ESC.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Mallanna
authors.forename: Briana D
authors.initials: BD
authors.lastname: Ormsbee
authors.forename: Michelina
authors.initials: M
authors.lastname: Iacovino
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Gilmore
authors.forename: Jesse L
authors.initials: JL
authors.lastname: Cox
authors.forename: Michael
authors.initials: M
authors.lastname: Kyba
authors.forename: Michael P
authors.initials: MP
authors.lastname: Washburn
authors.forename: Angie
authors.initials: A
authors.lastname: Rizzino
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D047468:Immunoprecipitation; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D051379:Mice; D054258:Neural Plate / Q000166:cytology / Q000378:metabolism; D039904:Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism*; D055749:SOXB2 Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D055748:SOXB1 Transcription Factors; D055749:SOXB2 Transcription Factors; C527783:Sox2 protein, mouse; C484489:Sox21 protein, mouse