Project description:The B1 SOX transcription factors SOX1/2/3/19 have been implicated in various processes of early embryogenesis. However, their regulatory functions in stages from the blastula to early neurula remain largely unknown, primarily because loss-of-function studies have not been informative to date. In our present study, we systematically knocked down the B1 sox genes in zebrafish. Only the quadruple knockdown of the four B1 sox genes sox2/3/19a/19b, which are active in the early embryo, resulted in very severe developmental abnormalities, confirming that the B1 sox genes are functionally redundant. We characterized the sox2/3/19a/19b quadruple knockdown embryos in detail by examining the changes in gene expression through microarray analysis as well as in situ hybridization. Importantly, these phenotypic analyses of the quadruple knockdown embryos reveled that the B1 SOX proteins regulate the following distinct processes: (1) early dorsoventral patterning by controlling bmp2b/7; (2) gastrulation movements via the regulation of pcdh18a/18b and non-canonical wnt genes; (3) neural differentiation by regulating the Hes-class bHLH gene her3 and the proneural-class bHLH genes neurog1 (positively) and ascl1a (negatively), and regional transcription factor genes, e.g. hesx1, zic1 and rx3; and (4) neural patterning by regulating signaling pathway genes, cyp26a1 in RA signaling, oep in Nodal signaling, shh, and mdkb. These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo. Microarray analysis was carried out to compare gene expression profiles at the 30% epiboly (30%E), 75% epiboly (75%E) and tailbud (TB) stages between wild-type embryos and the sox2/3/19a/19b quadruple knockdown embryos. RNAs from two independent samples were analyzed for each embryonic stage.
Project description:Epigenetic regulation of chromatin states is crucial for proper gene expression programs and progression during development, but precise mechanisms by which epigenetic factors influence differentiation remain poorly understood. Here we find that the histone variant H2A.Z accumulates at Sox motif-containing promoters during zebrafish gastrulation while neighboring genes become transcriptionally active. These changes coincide with reduced expression of anp32e, the H2A.Z histone removal chaperone, suggesting that loss of Anp32e may lead to increases in H2A.Z binding during differentiation. Remarkably, genetic removal of Anp32e in embryos leads to H2A.Z accumulation prior to gastrulation and developmental genes become precociously active. Accordingly, H2A.Z accumulation occurs most extensively at Sox motif-associated genes, including many which are normally activated following gastrulation. Altogether, our results provide compelling evidence for a mechanism in which Anp32e preferentially restricts H2A.Z accumulation at Sox motifs to regulate the initial phases of developmental differentiation in zebrafish.
Project description:The B1 SOX transcription factors SOX1/2/3/19 have been implicated in various processes of early embryogenesis. However, their regulatory functions in stages from the blastula to early neurula remain largely unknown, primarily because loss-of-function studies have not been informative to date. In our present study, we systematically knocked down the B1 sox genes in zebrafish. Only the quadruple knockdown of the four B1 sox genes sox2/3/19a/19b, which are active in the early embryo, resulted in very severe developmental abnormalities, confirming that the B1 sox genes are functionally redundant. We characterized the sox2/3/19a/19b quadruple knockdown embryos in detail by examining the changes in gene expression through microarray analysis as well as in situ hybridization. Importantly, these phenotypic analyses of the quadruple knockdown embryos reveled that the B1 SOX proteins regulate the following distinct processes: (1) early dorsoventral patterning by controlling bmp2b/7; (2) gastrulation movements via the regulation of pcdh18a/18b and non-canonical wnt genes; (3) neural differentiation by regulating the Hes-class bHLH gene her3 and the proneural-class bHLH genes neurog1 (positively) and ascl1a (negatively), and regional transcription factor genes, e.g. hesx1, zic1 and rx3; and (4) neural patterning by regulating signaling pathway genes, cyp26a1 in RA signaling, oep in Nodal signaling, shh, and mdkb. These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo.
Project description:This SuperSeries is composed of the following subset Series: GSE33059: Sequentially acting Sox transcription factors in neural lineage development [ChIP-seq] GSE33060: Sequentially acting Sox transcription factors in neural lineage development [RNA-seq] GSE33061: Sequentially acting Sox transcription factors in neural lineage development [microarray] Refer to individual Series
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.
Project description:We used DamID-seq to analyze the genome-wide binding patterns of the group B Sox proteins Dichaete and SoxNeuro in four species of Drosophila: D. melanogaster, D. simulans, D. yakuba and D. pseudoobscura. Both binding site turnover between species and a comparison of the binding properties of the two partially-redundant transcription factors were analyzed. We found that, despite widespread turnover, genomic intervals that are commonly bound by both Dichaete and SoxNeuro are highly conserved in Drosophila.
Project description:SOX transcription factors have important roles during astrocyte and oligodendrocyte development, but how glial genes are specified and activated in a sub-lineage specific fashion remains unknown. To address this question, we have defined glial specific gene expression in the developing spinal cord using single-cell RNA-sequencing. Moreover, conducting ChIP-seq analyses we show that these glial gene sets are extensively preselected already in multipotent neural precursor cells through the prebinding by SOX3. In the subsequent lineage-restricted glial precursor cells, astrocyte genes become additionally targeted by SOX9 at DNA-regions strongly enriched for Nfi binding-motifs, whereas oligodendrocyte genes become prebound by SOX9 only, at sites that during oligodendrocyte maturation are targeted by SOX10. Interestingly, reporter gene assays and functional studies in the spinal cord revealed that SOX3 binding represses the synergistic activation of astrocyte genes by SOX9 and NFIA, whereas oligodendrocyte genes are activated in a combinatorial manner by SOX9 and SOX10. These genome-wide studies demonstrate how sequentially expressed SOX proteins act on lineage-specific regulatory DNA-elements to coordinate glial gene expression both in a temporal and sub-lineage specific fashion.
Project description:Pluripotent stem cells are a hallmark of animal multicellularity. Sox and POU family transcription factors are pivotal for stemness and were believed to be animal innovations as they were reported absent from the genomes of their unicellular relatives. Here we describe new unicellular holozoan orthologues to Sox and POU families, indicating that they emerged before the appearance of animals. We show that choanoflagellate and filasterean Sox genes have DNA binding specificity similar to Sox2. Choanoflagellate Sox can partner with the POU member Oct4 on DNA elements found in pluripotency enhancers. Consistently, choanoflagellate – but not filasterean – Sox genes can replace Sox2 to reprogram mouse somatic cells into induced pluripotent stem cells (iPSC). In contrast, choanoflagellate POU harbors a unique DNA-binding profile that differs from Oct4 and cannot generate iPSCs. Pluripotency reprogramming with reconstructed ancestral Sox genes shows that their molecular ability to induce stemness was already present in the last common ancestor of animals and their unicellular relatives. Our findings imply that the evolution of stem cells exploited a pre-existing set of transcription factors, where the critical innovation involved an initial change in DNA specificity of POU and the exaptation of the ancestral capacity to interact with Sox transcription factors.
Project description:We report sequential binding but unique functions of different Sox transcription factors during distinct stages of neural differentiation Examination of genome-wide Sox2, Sox3 and Sox11 transcription factor binding during different stages of neurogenesis.
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.