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: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: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:Sall4 is a mouse homolog of a causative gene of the autosomal dominant disorder known as Okihiro syndrome. We previously showed that Sall4 absence leads to lethality during peri-implantation and that Sall4-null embryonic stem (ES) cells proliferate poorly with intact pluripotency when cultured on feeder cells. However, a subsequent report indicated that shRNA-mediated Sall4 inhibition in ES cells led to a severe reduction in Oct3/4 and a secondary increase in Cdx2, which resulted in complete differentiation into the trophectoderm when cultured in the feeder-free condition. So we profiled gene expression changes when Sall4 is deleted in ES cells in the presence or absence of feeder cells. key word: embryonic stem (ES) cell, Sall4, feeder
Project description:Stem cells self-renew or differentiate under the governance of a stem cell-specific transcriptional program with each transcription factor orchestrating the activities of a particular set of genes. Here we demonstrate that a single transcription factor is able to regulate distinct core circuitries in two different blastocyst-derived stem cell lines, embryonic stem (ES) and extra-embryonic endoderm (XEN) cells. The transcription factor, Sall4, is required for early embryonic development and for ES cell pluripotency. Sall4 is also expressed in XEN cells and depletion of Sall4 disrupts self-renewal and induces differentiation. Genome-wide analysis reveals Sall4 is regulating different gene sets in ES and XEN cells, and depletion of Sall4 targets in the respective cell types induces differentiation. With Oct4, Sox2 and Nanog, Sall4 forms a crucial interconnected auto-regulatory network in ES cells. In XEN cells, Sall4 regulates key XEN lineageassociated genes, Gata4, Gata6, Sox7 and Sox17. Our findings demonstrate how Sall4 functions as an essential stemness factor for two different stem cell lines. Keywords: ES/XEN comparison, ES Sall4 KD/control KD comparison, and XEN Sall4 KD/control KD comparison