Journal: Genome Research
Article Title: Tissular chromatin-state cartography based on double-barcoded DNA arrays that capture unloaded PA-Tn5 transposase
doi: 10.1101/gr.280305.124
Figure Lengend Snippet: Inferring chromatin-state transitions across the mouse embryo by integrating consecutive spatial epigenomic landscapes. ( A , left ) Scan of a DNA array (TRITC filter) hosting a cryosection of a mouse embryo (E11.5) and immunostained with an antibody targeting the histone modification H3K27-acetylation (H3K27ac). Notice the presence of Cyanin-3 (Cy3)-labeled DNA probes delimiting the DNA array composed of 32 × 32 interstitially printed probes. ( Middle ) DAPI staining. ( Right ) Digital map displaying the normalized read counts captured per physical position (SpExel) across the mouse embryo section. ( B ) t-SNE analysis allowing to stratify SpExel in six different clusters. ( Right ) Projection of the stratified clusters within the digital map. ( C ) Tissue–cell type gene marker association analysis performed per clusters identified in B . ( D ) Local enrichment signatures associated with six gene promoters presenting H3K27ac overrepresented counts. ( E ) In situ hybridization (ISH) and gene expression data (Allen Mouse Brain Atlas) for the genes Sox10 and Lhx5 , revealing their spatial signature, which is coherent with the H3K27ac digitized view displayed in D . ( F , left to right ) Histone modification immunostaining (TRITC filter: H3K4me3, H3K27me3), nuclei revealed by DAPI, digital map of the normalized read counts across the tissue section, and local read count enrichment associated to the gene Wnt11 . ( G ) Strategy for interrogating changes in chromatin histone modification signatures across the embryo: ( i ) overlay all three histone modification maps, ( ii ) generate a pseudomap in which SpExel of each digitized map are allocated to common pseudocoordinates, and ( iii ) interrogate for contiguous enrichment patterns similarity within tissue section but also across all three aligned sections. ( H ) Pseudomap obtained from the overlay of all three histone modification digital maps. ( I ) Promoter enrichment patterns associated to Wnt11 gene (more than five contiguous SpExel) retrieved in either of the histone modification maps. ( J ) Spatial gene promoter's coenrichment analysis for Wnt11 in the H3K27ac or H3K27me3 digital map. SpExel colored in red correspond to the location of Wnt11 , whereas others correspond to other gene promoters sharing a similar spatial pattern (Tanimoto similarity index). Notice that these two spatial gene promoter's coenrichment maps present distinct spatial localizations. ( K ) Heatmap displaying the co-occurring promoter enrichment patterns between all three histone modifications. Six chromatin co-occurring states were identified and functionally associated to either active, repressed, or bivalent promoters, as described previously ( , ). Notice the presence of two states for which no functional association has been attributed: H3K4me3, or H3K27ac alone. ( L ) Gene promoters presenting different chromatin co-occurring states across the tissue. ( M , top ) Local read counts promoter enrichment for the gene Hoxb4 in either of the histone modification maps within the pseudomap. ( Bottom ) Hoxb4 coenrichment patterns revealing the presence of either bivalent (H3K27me3/H3K27ac or H3K27me3/H3K4me3) or promoter active regions (H3K27ac/H3K4me3). ( N ) In situ hybridization (ISH) and gene expression data (Allen Mouse Brain Atlas) for the gene Hoxb4 , revealing its spatial signature coherent with the H3K27ac digitized view displayed in M .
Article Snippet: Like in our previous study describing the use of double-barcoded DNA arrays for spatial transcriptomics , we have used BCr oligonucleotides presenting an amino C6 linker at the 5′ extremity, followed by four G or C nucleotides (S), a T7 promoter sequence (GACTCGTAATACGACTCACTATAGGG), a unique molecular identifier (UMI; WSNNWSNNV), a molecular barcode (8 nt) associated to the printed row in the DNA array, and a 30 nt adapter sequence with a GC-content of 40% (here named as Gibson sequence “ACATTGAAGAACCTG-TAGATAACTCGCTGT”).
Techniques: DNA Array, Modification, Labeling, Staining, Marker, In Situ Hybridization, Gene Expression, Immunostaining, Functional Assay