Fig. 3

Figure 3. Selected pacemaker cell (PC)–enriched assay for transposase-accessible chromatin (ATAC-seq) peaks are sufficient to direct reporter activity to the cardiac venous inflow and sinoatrial node.A, ATAC-seq signal in PC (green track) and right atrial cardiomyocytes (RACM, red track) at the Rgs6 locus (top) and the Ptgfr locus (bottom) with differentially accessible (DA) ATAC-seq peaks highlighted in yellow. B, Three founders from transient transgenic enhancer-reporter mice generated with enSERT (enhancer inSERTion) and deposited in the VISTA Enhancer Browser (VISTA) at enhancer.lbl.gov for the DA ATAC-seq peak at Rgs6 locus (VISTA ID mm2011) and (C) Ptgfr locus (VISTA ID mm2010), harvested at embryonic day (E) 11.5 and stained with X-gal. Lower, Magnified view of the venous inflow (arrow) and right atrium (ra). D, DA ATAC-seq peak at the Isl1 locus is highlighted in yellow. E–J, Whole-mount images of ISE-LacZ embryos harvested and stained with salmon-gal at E8.5 (E) or bluo-gal at the developmental time points shown up to postnatal day 2 (P2; F–J). K, Double immunohistochemistry for Hcn4 (hyperpolarization-activated, cyclic nucleotide-gated ion channel 4) and β-gal (beta-galactosidase) in the sinoatrial node (SAN) of E14.5 ISE-LacZ embryo. L, Whole-mount image of an adult ISE-LacZ SAN stained with bluo-gal. a indicates atrium; la, left atrium; lv, left ventricle; oft, outflow tract; ra, right atrium; rv, right ventricle; sv, sinus venosus; and v, ventricle.