Sphingosine 1-phosphate-regulated transcriptomes in heterogenous arterial and lymphatic endothelium of the aorta

Despite the medical importance of G protein-coupled receptors (GPCRs), in vivo cellular heterogeneity of GPCR signaling and downstream transcriptional responses are not understood. While endothelial S1pr1 expression is ubiquitous (Kaur et al., 2017), receptor activation in vivo, as reported by GFP in S1PR1-GS mice, revealed heterogeneous signaling in multiple organs (Kono et al., 2014), including in the aorta (Galvani et al., 2015). To gain insights into the molecular mechanisms of S1PR1 regulation of endothelial transcription and the heterogenous nature of S1PR1 signaling in vivo, we performed transcriptome (bulk and single-cell RNA-seq) and open chromatin profiling (ATAC-seq) of FACS-sorted adult mouse aortic endothelial cells (MAECs) with high (GFPhigh) or low (GFPlow) reporter expression. We also performed bulk transcriptome and open chromatin profiling of MAECs from tamoxifen-treated Cdh5-CreERT2 S1pr1f/f (S1pr1-ECKO) and S1pr1f/f (S1pr1-WT) littermates. MAECs were defined as CD45-Ter119-DAPI-CD31+. The CD31 antibody used was PE-conjugated rat anti-mouse clone MEC13.3 from BD Biosciences. Overall design: Cells from 2-4 aortae of age and sex-matched adult mice were pooled for each individual experiment (ATAC-seq, RNA-seq and scRNA-seq). N=3 for each MAEC population for all bulk comparisons.