Project description:Precise spatiotemporal orchestration of gene expression is required for proper embryonic development. The application of high throughput single-cell technologies have provided comprehensive transcriptomic definitions of cell states within the embryo, but our knowledge of their spatial localization remains elusive. To explore early mouse organogenesis, we used Slide-seq to generate high-resolution maps of whole E8.5 and E9.5 mouse embryos. We developed sc3D, a tool for creating a three-dimensional (3D) 'digital embryo,' which allowed us to quantitatively decipher regionalized gene expression across multiple tissues. Our transcriptomic atlas facilitated us to characterize gene expression patterns along the anteroposterior and dorsoventral axes, with a particular emphasis on neural tube development. We nominated and functionally characterized Prdm8, a histone methyltransferase, as a neural tube patterning gene. Furthermore, we were able to determine the transcriptional identity of ectopic neural tubes in a classical Tbx6 mutant, which provided us with additional insights into neural tube patterning. Taken together, we combined computational and experimental tools to generate a framework that enables systematic spatiotemporal dissection of complex embryonic structures via high-throughput profiling of molecular phenotypes, thereby paving the way for the investigation of congenital and developmental abnormalities.
Project description:Epigenetic mechanisms set apart the active and inactive regions in the genome of multicellular organisms to produce distinct cell fates during embryogenesis. Here, we report on the epigenetic and transcriptome genome-wide maps of gastrula-stage Xenopus tropicalis embryos using massive parallel sequencing of cDNA (RNA-seq) and DNA obtained by chromatin immunoprecipitation (ChIP-seq) of histone H3 K4 and K27 trimethylation and RNA Polymerase II (RNAPII). These maps identify promoters and transcribed regions. Strikingly, genomic regions featuring opposing histone modifications are mostly transcribed, reflecting spatially regulated expression rather than bivalency as determined by expression profile analyses, sequential ChIP, and ChIP-seq on dissected embryos. Spatial differences in H3K27me3 deposition are predictive of localized gene expression. Moreover, the appearance of H3K4me3 coincides with zygotic gene activation, whereas H3K27me3 is predominantly deposited upon subsequent spatial restriction or repression of transcriptional regulators. These results reveal a hierarchy in the spatial control of zygotic gene activation. ChIP-seq profiles of two histone modifications (H3K4me3 and H3K27me3) and RNA Polymerase II, and a RNA-seq profile, of gastrula stage Xenopus tropicalis embryos
Project description:Epigenetic mechanisms set apart the active and inactive regions in the genome of multicellular organisms to produce distinct cell fates during embryogenesis. Here, we report on the epigenetic and transcriptome genome-wide maps of gastrula-stage Xenopus tropicalis embryos using massive parallel sequencing of cDNA (RNA-seq) and DNA obtained by chromatin immunoprecipitation (ChIP-seq) of histone H3 K4 and K27 trimethylation and RNA Polymerase II (RNAPII). These maps identify promoters and transcribed regions. Strikingly, genomic regions featuring opposing histone modifications are mostly transcribed, reflecting spatially regulated expression rather than bivalency as determined by expression profile analyses, sequential ChIP, and ChIP-seq on dissected embryos. Spatial differences in H3K27me3 deposition are predictive of localized gene expression. Moreover, the appearance of H3K4me3 coincides with zygotic gene activation, whereas H3K27me3 is predominantly deposited upon subsequent spatial restriction or repression of transcriptional regulators. These results reveal a hierarchy in the spatial control of zygotic gene activation.
Project description:We applied a spatially resolved, high-dimensional transcriptomic approach to study MPM morpho-logical evolution. 139 regions across 8 biphasic MPMs (B-MPMs) were profiled using the GeoMx™Digital Spatial Profiler and Cancer Transcriptome Atlas to compare epithelioid and sarcomatoid components transcriptional profile and reconstruct the positional context of transcriptional activities and the spatial topology of MPM cells interactions.
Project description:The mammalian brain can be divided into distinct structural and functional regions to perform a variety of diverse functions, but during normal aging, exactly how each region is affected, and the information interaction changes between different regions, remains largely unknown. To gain a better insight into these processes, here we generate a single-cell spatial transcriptomic (ST) atlas of young and old mice brains involving cerebrum, brain stem and fiber tracts regions. Based on the unbiased classification of spatial molecular atlas, 27 distinguished brain spatial domains were obtained, which are similar to known anatomical regions, but slightly different. Through differential expression analysis and gene set enrichment analysis (GSEA), we identified aging-related genes and pathways that vary in a coordinated or opposite manner across regions. Combined with single-cell transcriptomic data, we characterized the spatial distribution of cell types, identified an up-regulated gene Ifi27 across regions and cell types in VIS region. Through ligand-receptor interaction analysis, we identified all possible information interaction changes between regions with aging. In summary, we establish a brain spatial molecular atlas (accessible online at https:) to provide a rich resource of spatially differentially expressed genes and information interaction, which may help to understand aging and provide novel insights into the molecular mechanism of brain aging.
Project description:The mammalian brain consists of millions to billions of cells that are organized into numerous cell types with specific spatial distribution patterns and structural and functional properties. An essential step towards understanding brain function is to obtain a parts list, i.e., a catalog of cell types, of the brain. Here, we report a comprehensive and high-resolution transcriptomic and spatial cell type atlas for the whole adult mouse brain. The cell type atlas was created based on the combination of two single-cell-level, whole-brain-scale datasets: a single-cell RNA-sequencing (scRNA-seq) dataset of ~7 million cells profiled (~4.0 million cells passing quality control), and a spatially resolved transcriptomic dataset of ~4.3 million cells using MERFISH. The atlas is hierarchically organized into four nested levels of classification: 34 classes, 338 subclasses, 1,201 supertypes and 5,322 clusters. We present a newly developed online platform, Allen Brain Cell (ABC) Atlas, to visualize the mouse whole brain cell type taxonomy and atlas along with the scRNA-seq and MERFISH data and metadata sets. We systematically analyzed the neuronal, non-neuronal, and immature neuronal cell types across the brain and identified a high degree of correspondence between transcriptomic identity and spatial specificity for each cell type. The results reveal unique features of cell type organization in different brain regions, in particular, a dichotomy between the dorsal and ventral parts of the brain: the dorsal part contains relatively fewer yet highly divergent neuronal types, whereas the ventral part contains more numerous neuronal types that are more closely related to each other. We also systematically characterized cell-type specific expression of neurotransmitters, neuropeptides, and transcription factors. The study uncovered extraordinary diversity and heterogeneity in neurotransmitter and neuropeptide expression and co-expression patterns in different cell types across the brain, suggesting they mediate myriad modes of intercellular communications. Finally, we found that transcription factors are major determinants of cell type classification in the adult mouse brain and identified a combinatorial transcription factor code that defines cell types across all parts of the brain. The whole-mouse-brain transcriptomic and spatial cell type atlas establishes a benchmark reference atlas and a foundational resource for deep and integrative investigations of cellular and circuit function, development, and evolution of the mammalian brain.
Project description:Somatic cell nuclear transfer, a technique used to generate clone embryos by transferring the nucleus of a somatic cell into an enucleated oocyte, is an excellent approach to study the reprogramming of the nuclei of differentiated cells. Here, we conducted a transcriptomic study by performing microarray analysis on single Sertoli cell nuclear transfer (SeCNT) embryos throughout preimplantation development. The extensive data collected from the oocyte to the blastocyst stage helped to identify specific genes that were incorrectly reprogrammed at each stage, thereby providing a novel perspective for understanding reprogramming progression in SeCNT embryos.This attempt provided an opportunity to discuss the possibility that ectopic gene expression could be involved in the developmental failure of SeCNT embryos. Network analysis at each stage suggested that in total, 127 networks were involved in developmental and functional disorders in SeCNT embryos. Furthermore, chromosome mapping using our time-lapse expression data highlighted temporal–spatial changes of the abnormal expression, showing the characteristic distribution of the genes on each chromosome.Thus, the present study revealed that the preimplantation development of SeCNT embryos appears normal; however, the progression of incorrect reprogramming is concealed throughout development.