Project description:This SuperSeries is composed of the following subset Series: GSE21054: Differential roles of Sall4 isoforms in ES cell pluripotency: expression GSE21055: Differential Role of Sall4 isoforms in ES cell pluripotency: ChIP-chip Refer to individual Series
Project description:Sall4 is a transcription factor essential for early mammalian development. Though it is reported to play an important role in embryonic stem (ES) cell self-renewal, whether it is an essential pluripotency factor has been disputed. Though Sall4 is known to associate with the Nucleosome Remodeling and Deacetylase (NuRD) complex, the nature of this interaction is unclear as NuRD and Sall4 serve opposing functions in ES cells. Here we use defined culture conditions and single-cell gene expression analyses to show that Sall4 prevents activation of the neural gene expression programme in ES cells but is dispensable for maintaining the pluripotency gene regulatory network. We further show using genome-wide analyses that while Sall4 interacts with NuRD, it neither recruits NuRD to chromatin nor influences transcription via NuRD. Rather we propose a model where, by titrating Sall4 protein, NuRD limits the differentiation-inhibiting activity of Sall4 in ES cells to enable lineage commitment.
Project description:Embryonic stem cells have potential utility in regenerative medicine due to their pluripotent characteristics. Sall4, a zinc-finger transcription factor, is expressed very early in embryonic development with Oct4 and Nanog, two well characterized pluripotency regulators. Sall4 plays an important role in governing the fate of stem cells through transcriptional regulation of both Oct4 and Nanog. Using chromatin immunoprecipitation coupled to microarray hybridization (ChIP on Chip), we have mapped global gene targets of Sall4 unveiling possible regulation of broad ES cell functions. Approximately 5,000 genes were identified that were bound by the Sall4 protein and many of these have major functions in developmental and regulatory pathways. Sall4 bound more than six times as many annotated genes within promoter regions as Oct4 and twice as many as Nanog. Immunoprecipitation revealed a heterotrimeric protein complex between Sall4, Oct4, and Nanog, consistent with binding site co-occupancies. Further, Sall4 bound many genes that are regulated in part by the chromatin-based epigenetic events mediated by polycomb-repressive complexes and bivalent domains. This suggests that Sall4 plays a central and diverse role in regulating stem cell pluripotency during early embryonic development that involves integration of transcriptional and epigenetic control processes. Keywords: ChIP-chip We used ChIP-chip to map global promoter bound by Sall4, a zinc finger transcription factor. Growing evidence has suggested that Sall4 plays a vital role in ES cell pluripotency maintenance. Evidence for this includes its recent use as a marker for somatic cell reprogramming, in a genetic signature for ES cells, and evidence that Sall4 enhances reprogramming. These recent findings and two previously described interactions with Oct4 and Nanog strongly support the role of Sall4 in ES cells. This hypothesis was furthered here as we show that Sall4 plays important roles through transcriptional regulation of vital ES cell genes.
Project description:Embryonic stem cells have potential utility in regenerative medicine due to their pluripotent characteristics. Sall4, a zinc-finger transcription factor, is expressed very early in embryonic development with Oct4 and Nanog, two well characterized pluripotency regulators. Sall4 plays an important role in governing the fate of stem cells through transcriptional regulation of both Oct4 and Nanog. Using chromatin immunoprecipitation coupled to microarray hybridization (ChIP on Chip), we have mapped global gene targets of Sall4 unveiling possible regulation of broad ES cell functions. Approximately 5,000 genes were identified that were bound by the Sall4 protein and many of these have major functions in developmental and regulatory pathways. Sall4 bound more than six times as many annotated genes within promoter regions as Oct4 and twice as many as Nanog. Immunoprecipitation revealed a heterotrimeric protein complex between Sall4, Oct4, and Nanog, consistent with binding site co-occupancies. Further, Sall4 bound many genes that are regulated in part by the chromatin-based epigenetic events mediated by polycomb-repressive complexes and bivalent domains. This suggests that Sall4 plays a central and diverse role in regulating stem cell pluripotency during early embryonic development that involves integration of transcriptional and epigenetic control processes. Keywords: ChIP-chip
Project description:Murine embryonic stem cells (ESCs) are defined by continuous self-renewal and pluripotency. A diverse repertoire of protein isoforms arising from alternative splicing are expressed in ES cells without defined biological roles. Sall4, a transcription factor essential for pluripotency, exists as two isoforms (Sall4a and Sall4b). By genome-wide location analysis, we have determined that Sall4b, and not Sall4a, binds preferentially to highly expressed loci in ES cells. Sall4a and Sall4b binding sites are distinguished by both epigenetic marks at target loci and their clustering with binding sites of other pluripotency factors. When ESCs expressing a single isoform of Sall4 are generated, Sall4b alone could maintain the pluripotent state, although it could not completely suppress all differentiation markers. Sall4a and Sall4b collaborate in maintenance of the pluripotent state, but play distinct roles. Our work is novel in establishing such isoform-specific differences in ES cells.
Project description:Murine embryonic stem cells (ESCs) are defined by continuous self-renewal and pluripotency. A diverse repertoire of protein isoforms arising from alternative splicing are expressed in ES cells without defined biological roles. Sall4, a transcription factor essential for pluripotency, exists as two isoforms (Sall4a and Sall4b). By genome-wide location analysis, we have determined that Sall4b, and not Sall4a, binds preferentially to highly expressed loci in ES cells. Sall4a and Sall4b binding sites are distinguished by both epigenetic marks at target loci and their clustering with binding sites of other pluripotency factors. When ESCs expressing a single isoform of Sall4 are generated, Sall4b alone could maintain the pluripotent state, although it could not completely suppress all differentiation markers. Sall4a and Sall4b collaborate in maintenance of the pluripotent state, but play distinct roles. Our work is novel in establishing such isoform-specific differences in ES cells.
Project description:A small number of transcription factors, including Oct-3/4 and Sox2, constitute the transcriptional network that maintains pluripotency in embryonic stem (ES) cells. Previous reports suggested that some of these factors form a complex that binds the Oct-Sox element, a composite sequence consisting of closely juxtaposed Oct-3/4-binding and Sox2-binding sites. However, little is known regarding the components of the complex. In this study, we show that Sall4, a member of the Spalt-like family of proteins, directly interacts with Sox2 and Oct-3/4. Sall4 in combination with Sox2 or Oct-3/4 simultaneously occupies the Oct-Sox elements in mouse ES cells. Sall4 knockdown led to differentiation of ES cells. Overexpression of Sall4 in ES cells increased reporter activities in a luciferase assay when the Pou5f1- or Nanog-derived Oct-Sox element was included in the reporter. Microarray analyses revealed that Sall4 and Sox2 bound to the same genes in ES cells significantly more frequently than expected from random coincidence. These factors appeared to bind the promoter regions of a subset of the Sall4- and Sox2-double-positive genes in precisely similar distribution patterns along the promoter regions, suggesting that Sall4 and Sox2 associate with such Sall4/Sox2-overlapping genes as a complex. Importantly, gene ontology analyses indicated that the Sall4/Sox2-overlapping gene set is enriched for genes involved in maintaining pluripotency. Sall4/Sox2/Oct-3/4-triple-positive genes identified by referring to a previous study identifying Oct-3/4-bound genes in ES cells were further enriched for pluripotency genes than Sall4/Sox2-double-positive genes. These results demonstrate that Sall4 contributes to the transcriptional network operating in pluripotent cells, together with Oct-3/4 and Sox2. ChIP-on-chip experiments using anti-Sall4 or anti-Sox2 antibody were performed.