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: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:Ptf1a is a lineage-specific basic-helix-loop-helix transcription factor critical in the development of both the pancreas and nervous system. How one transcription factor controls diverse programs of gene expression is a fundamental question in developmental biology. To uncover molecular strategies for the program-specific functions of Ptf1a, we identified bound genomic regions in vivo during development of both tissues. A majority of regions bound by Ptf1a are tissue-specific, lie near genes needed for proper formation and maturation of each tissue, and reflect regions of open chromatin.M-BM- M-BM- Information for the specificity of Ptf1a binding and function is encoded in the DNA surrounding the Ptf1a-bound sites, since Ptf1a-bound regions are sufficient to direct tissue-restricted reporter expression when tested in transgenic mice. Fox and Sox factors were identified as lineage specific modifiers ofM-BM- Ptf1a binding, sinceM-BM- binding motifs for these factors are enriched in Ptf1a-bound regions in pancreas and neural tube, respectively. Although Ptf1a and Foxa2 co-localize to sites in embryonic pancreas and can act synergistically in cell transfection assays, biochemical experiments detected no physical interaction between the two factors. These findingsM-BM- indicateM-BM- that lineage-specific chromatin landscapes likely constrain the functions of Ptf1a, and identify Fox and Sox gene families as part of this process. RNA-Seq: Examination of gene expression in Ptf1a expressing cells (NT E.12.5, Pancreas E15.5) ChIP-Seq: Examination of chromatin occupancy in 2 tissue types (E12.5 NT and 17.5 Pancreas). Faire-Seq: Examination of open chromatin in 2 tissue types (E12.5 NT and 17.5 Pancreas).
Project description:The proper balance of excitatory and inhibitory neurons is crucial to normal processing of somatosensory information in the dorsal spinal cord. Two neural basic helix-loop-helix transcription factors, Ascl1 and Ptf1a, are essential for generating the correct number and sub-type of neurons in multiple regions of the nervous system. M-BM- In the dorsal spinal cord, Ascl1 and Ptf1a have contrasting functions in specifying inhibitory versus excitatory neurons. To understand how Ascl1 and Ptf1a function in these processes, we identified their direct transcriptional targets genome-wide in the embryonic mouse neural tube using ChIP-Seq and RNA-Seq. We show that Ascl1 and Ptf1a regulate the specification of excitatory and inhibitory neurons in the dorsal spinal cord through direct regulation of distinct homeodomain transcription factors known for their function in neuronal sub-type specification. Besides their roles in regulating these homeodomain factors, Ascl1 and Ptf1a each function differently during neuronal development with Ascl1 directly regulating genes with roles in several steps of the neurogenic program including, Notch signaling, neuronal differentiation, axon guidance, and synapse formation. In contrast, Ptf1a directly regulates genes encoding components of the neurotransmitter machinery in inhibitory neurons, and other later aspects of neural development distinct from those regulated by Ascl1. Moreover, Ptf1a represses the excitatory neuronal fate by directly repressing several targets of Ascl1. Examination of the Ascl1 and Ptf1a bound sequences shows they are enriched for a common E-Box with a GC core and with additional motifs used by Sox, Rfx, Pou, and Homeodomain factors. Ptf1a bound sequences are uniquely enriched in an E-Box with a GA/TC core and in the binding motif for its co-factor Rbpj, providing two keys to specificity of Ptf1a binding. The direct transcriptional targets identified for Ascl1 and Ptf1a provide a molecular understanding for how they function in neuronal development, particularly as key regulators of homeodomain transcription factors required for neuronal sub-type specification. Examination of gene expression in Ascl1 and Ptf1a lineage cells in the developing neural tube.
Project description:<p>During development of the human brain, multiple cell types with diverse regional identities are generated. Here we report a system to generate early human brain forebrain and mid/hindbrain cell types from human embryonic stem cells (hESCs), and infer and experimentally confirm a lineage tree for the generation of these types based on single-cell RNA-Seq analysis. We engineered <i>SOX2<sup>Cit/+</sup></i> and <i>DCX<sup>Cit/Y</sup></i> hESC lines to target progenitors and neurons throughout neural differentiation for single-cell transcriptomic profiling, then identified discrete cell types consisting of both rostral (cortical) and caudal (mid/hindbrain) identities. Direct comparison of the cell types were made to primary tissues using gene expression atlases and fetal human brain single-cell gene expression data, and this established that the cell types resembled early human brain cell types, including preplate cells. From the single-cell transcriptomic data a Bayesian algorithm generated a unified lineage tree, and predicted novel regulatory transcription factors. The lineage tree highlighted a prominent bifurcation between cortical and mid/hindbrain cell types, confirmed by clonal analysis experiments. We demonstrated that cell types from either branch could preferentially be generated by manipulation of the canonical Wnt/beta-catenin pathway. In summary, we present an experimentally validated lineage tree that encompasses multiple brain regions, and our work sheds light on the molecular regulation of region-specific neural lineages during human brain development.</p>
Project description:We report sequential binding but unique functions of different Sox transcription factors during distinct stages of neural differentiation