XB-IMG-151838
Xenbase Image ID: 151838
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Figure 4. CHD7 and PBAF bind distal regulatory elements upstream of NC transcription factors and synergistically regulate NC gene expression and migration in vivo. a, In hNCLCs CHD7 and BRG1 co-occupy the NCspecific distal enhancer controlling SOX9 expression. Top: schematic representation of the SOX9 locus, showing the relative positions of primer sets (P1–P3) used for ChIP–quantitative polymerase chain reaction (qPCR) analyses, NC-specific (NCE) and notochord, gut and pancreas-specific (NGPE) SOX9 distal enhancers, as identified in ref. 9. Bottom: ChIP–qPCR analyses of H3K4me1, H3K4me3, CHD7 and BRG1 levels at P1–P3 genomic regions in hNCLCs. b, In hNCLCs CHD7 and BRG1 co-occupy a conserved distal element located upstream from the TWIST1 TSS. Top: schematic representation of the TWIST1 locus, showing the relative positions of primer sets (P1 and P2) used for ChIP–qPCR analyses. The conservation index for 31 eutherian mammals (ENSEMBL) is shown below. Bottom: ChIP–qPCR analyses of H3K4me1, H3K4me3, CHD7 and BRG1 levels at P1 and P2 genomic regions. In a and b the y axes show the percentage of input recovery; error bars represent s.d. from three technical replicates of a representative experiment. Ctrl, control. c, Synergistic effect of Chd7 and Brd7 MOs on Twist expression. Twist in situ hybridization analyses of early-tailbud embryos injected with the indicated doses of Chd7 and/or Brd7 MOs into a single DA blastomere at the eight-cell stage. All injection volumes were kept constant. Representative images of the injected (top) and uninjected (bottom) side of the same embryo are shown. Asymmetry in Twist expression is quantified in the bottom graph. d, Synthetic effect of Chd7 and Brd7 MOs on NC migration. Analysis of cell migration to pharyngeal arches in tadpoles derived from eight-cell stage embryos co-injected with fluorescent lineage tracer and indicated MOs into a single DA blastomere. Quantification of cell migration to pharyngeal arches (PA) is shown in the bottom graph. P values in c and d were calculated by Fisher’s exact test for count data. e, Model of CHD7 function in neural crest formation. We propose that CHD7 and PBAF synergistically, and in a tissue-specificmanner, regulate activity of distal elements controlling expression of critical NC transcription factors. Activation of NC transcriptional circuitry in turn permits gene expression reprogramming, leading to epithelial–mesenchymal transition (EMT), acquisition of multipotency and migratory potential. Image published in: Bajpai R et al. (2010) Copyright © 2010. Image reproduced with permission of the Publisher, Macmillan Publishers Ltd. Larger Image Printer Friendly View |