title: Hhex and Cer1 mediate the Sox17 pathway for cardiac mesoderm formation in embryonic stem cells.
abstract: Cardiac muscle differentiation in vivo is guided by sequential growth factor signals, including endoderm-derived diffusible factors, impinging on cardiogenic genes in the developing mesoderm. Previously, by RNA interference in AB2.2 mouse embryonic stem cells (mESCs), we identified the endodermal transcription factor Sox17 as essential for Mesp1 induction in primitive mesoderm and subsequent cardiac muscle differentiation. However, downstream effectors of Sox17 remained to be proven functionally. In this study, we used genome-wide profiling of Sox17-dependent genes in AB2.2 cells, RNA interference, chromatin immunoprecipitation, and luciferase reporter genes to dissect this pathway. Sox17 was required not only for Hhex (a second endodermal transcription factor) but also for Cer1, a growth factor inhibitor from endoderm that, like Hhex, controls mesoderm patterning in Xenopus toward a cardiac fate. Suppressing Hhex or Cer1 blocked cardiac myogenesis, although at a later stage than induction of Mesp1/2. Hhex was required but not sufficient for Cer1 expression. Over-expression of Sox17 induced endogenous Cer1 and sequence-specific transcription of a Cer1 reporter gene. Forced expression of Cer1 was sufficient to rescue cardiac differentiation in Hhex-deficient cells. Thus, Hhex and Cer1 are indispensable components of the Sox17 pathway for cardiopoiesis in mESCs, acting at a stage downstream from Mesp1/2.
authors.affiliation: Center for Cardiovascular Development, Baylor College of Medicine, Houston, Texas, USA; Institute for Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Ruri
authors.initials: R
authors.lastname: Kaneda
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Leja
authors.forename: Tatiana
authors.initials: T
authors.lastname: Subkhankulova
authors.forename: Oleg
authors.initials: O
authors.lastname: Tolmachov
authors.forename: Gabriella
authors.initials: G
authors.lastname: Minchiotti
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schwartz
authors.forename: Mauricio
authors.initials: M
authors.lastname: Barahona
authors.forename: Michael D
authors.initials: MD
authors.lastname: Schneider
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019521:Body Patterning / Q000187:drug effects; D002454:Cell Differentiation / Q000235:genetics; D016207:Cytokines; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D016678:Genome; D024002:HMGB Proteins / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism*; D028322:Inhibin-beta Subunits / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000196:embryology*; D051379:Mice; D008954:Models, Biological; D024510:Muscle Development / Q000235:genetics; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D055457:Nodal Protein / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D011506:Proteins / Q000378:metabolism*; D055760:SOXF Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C110586:Cer1 protein, mouse; D016207:Cytokines; D024002:HMGB Proteins; C513080:Hhex protein, mouse; D018398:Homeodomain Proteins; D055457:Nodal Protein; C526008:Nodal protein, mouse; D011506:Proteins; D055760:SOXF Transcription Factors; C511606:Sox17 protein, mouse; D014157:Transcription Factors; C103008:inhibin beta A subunit; D028322:Inhibin-beta Subunits
keywords: Cardiac development; Embryonic stem cells; Endoderm; Myogenesis; RNA interference