Project description:Glioma contains malignant cells in diverse states. Here, we combine spatial transcriptomics with novel computational approaches to uncover the organization of glioma cellular states. We find three prominent modes of organization. First, cells in any given state tend to be spatially clustered, with local environments that are each enriched with one major cellular state. Second, specific pairs of states preferentially reside in proximity across multiple scales. Third, the pairwise interactions that we detect collectively define a global architecture composed of five layers. Hypoxia appears to drive this 5-layered organization, as it is associated with a long-range organization that extends from the hypoxic core to the infiltrative edge of the tumor. Accordingly, tumor regions distant from any hypoxic foci are less organized. In summary, we provide a conceptual framework for the organization of gliomas and highlight the role of hypoxia as a potential long-range tissue organizer.
Project description:Abstract from manuscript Glioblastoma develops an immunosuppressive microenvironment that fosters tumorigenesis and resistance to current therapeutic strategies. Here we use multiplexed tissue imaging and single-cell RNA-sequencing to characterize the composition, spatial organization, and clinical significance of extracellular purinergic signaling in glioblastoma. We show that glioblastoma exhibit strong expression of CD39 and CD73 ectoenzymes, correlating with increased adenosine levels. Microglia are the predominant source of CD39, while CD73 is principally expressed by tumor cells, particularly in tumors with amplification of EGFR and astrocyte-like differentiation. Spatially-resolved single-cell analyses demonstrate strong spatial correlation between tumor CD73 and microglial CD39, and that their spatial proximity is associated with poor clinical outcomes. Together, this data reveals that tumor CD73 expression correlates with tumor genotype, lineage differentiation, and functional states, and that core purine regulatory enzymes expressed by neoplastic and tumor-associated myeloid cells interact to promote a distinctive adenosine-rich signaling niche and immunosuppressive microenvironment potentially amenable to therapeutic targeting.
Project description:The nuclear organization of the genome is accepted as an important feature of gene expression regulation. However, it has remained unknown what the spatial organization of a single transcribed gene is. Here, we made use of several long highly expressed mammalian genes to describe their structure and spatial arrangement during transcription. We demonstrate that an expressed gene forms a transcription loop with RNA polymerases moving along the loop and carrying nascent RNAs that undergo co-transcriptional splicing. Transcription loops dynamically modify their harboring loci and extend into the nuclear interior due to their intrinsic stiffness. We hypothesize that the stiffness of the transcription loop arises due to a dense decoration of gene-axis with multiple voluminous nascent ribonucleoprotein particles, thus creating a stiff polymer bottlebrush. and provide supporting evidence to this hypothesis. Our work suggests that transcription loop formation is a universal principle of eukaryotic gene expression.
Project description:The extent to which the three-dimensional organization of the genome contributes to chromosomal translocations is an important question in cancer genomics. We now have generated a high-resolution Hi-C spatial organization map of the G1-arrested mouse pro-B cell genome and mapped translocations from target DNA double-strand breaks (DSBs) within it via high-throughput genome-wide translocation sequencing. RAG endonuclease-cleaved antigen-receptor loci are dominant translocation partners for target DSBs regardless of genomic position, reflecting high frequency DSBs at these loci and their co-localization in a fraction of cells. To directly assess spatial proximity contributions, we normalized genomic DSBs via ionizing-radiation. Under these conditions, translocations were highly enriched in cis along single chromosomes containing target DSBs and within other chromosomes and sub-chromosomal domains in a manner directly related to pre-existing spatial proximity. Our studies reveal the power of combining two high-throughput genomic methods to address long-standing questions in cancer biology. Hi-C interaction maps for WT and ATM -/- G1-arrested AMuLV-transformed pro-B cell lines.
Project description:Spatial organization of the transcriptome has emerged as a powerful means for regulating the post-transcriptional fate of RNA in eukaryotes; however, whether prokaryotes use RNA spatial organization as a mechanism for post-transcriptional regulation remains unclear. Here we used super-resolution microscopy to image the E. coli transcriptome and observed a genome-wide spatial organization of RNA: mRNAs encoding inner-membrane proteins are enriched at the membrane, whereas mRNAs encoding outer-membrane, cytoplasmic and periplasmic proteins are distributed throughout the cytoplasm. Membrane enrichment is caused by co-translational insertion of signal peptides recognized by the signal-recognition particle. Our time-resolved RNA-sequencing and live-cell super-resolution imaging experiments revealed a physiological consequence of this spatial organization and the underlying mechanism: membrane localization enhances degradation rates of inner-membrane-protein mRNAs by placing them in proximity to membrane-bound RNA degradation enzymes. Together, these results demonstrate that the bacterial transcriptome is spatially organized and that this organization shapes the posttranscriptional Spatial organization of the transcriptome has emerged as a powerful means for regulating the post-transcriptional fate of RNA in eukaryotes; however, whether prokaryotes use RNA spatial organization as a mechanism for post-transcriptional regulation remains unclear. Here we used super-resolution microscopy to image the E. coli transcriptome and observed a genome-wide spatial organization of RNA: mRNAs encoding inner-membrane proteins are enriched at the membrane, whereas mRNAs encoding outer-membrane, cytoplasmic and periplasmic proteins are distributed throughout the cytoplasm. Membrane enrichment is caused by co-translational insertion of signal peptides recognized by the signal-recognition particle. Our time-resolved RNA-sequencing and live-cell super-resolution imaging experiments revealed a physiological consequence of this spatial organization and the underlying mechanism: membrane localization enhances degradation rates of inner-membrane-protein mRNAs by placing them in proximity to membrane-bound RNA degradation enzymes. Together, these results demonstrate that the bacterial transcriptome is spatially organized and that this organization shapes the post-transcriptional dynamics of mRNAs.
Project description:The nuclear organization of the genome is accepted as an important feature of gene expression regulation. However, it has remained unknown what the spatial organization of a single transcribed gene is. Here, we made use of several long highly expressed mammalian genes to describe their structure and spatial arrangement during transcription. We demonstrate that an expressed gene forms a transcription loop with RNA polymerases moving along the loop and carrying nascent RNAs that undergo co-transcriptional splicing. Transcription loops dynamically modify their harboring loci and extend into the nuclear interior due to their intrinsic stiffness. We hypothesize that the stiffness of the transcription loop arises due to a dense decoration of gene-axis with multiple voluminous nascent ribonucleoprotein particles and provide supporting evidence to this hypothesis. Our work suggests that transcription loop formation is a universal principle of eukaryotic gene expression.