The transcriptomic and epigenetic map of vascular quiescence in the continuous lung endothelium

Abstract

Maintenance of a quiescent and organotypically-differentiated layer of blood vessel-lining endothelial cells (EC) is vital for human health. Yet, the molecular mechanisms of vascular quiescence remain largely elusive. Here we identify the genome-wide transcriptomic program controlling the acquisition of quiescence by comparing lung EC of infant and adult mice, revealing a prominent regulation of TGFß family members. These transcriptomic changes are distinctly accompanied by epigenetic modifications, measured at single CpG resolution. Gain of DNA methylation affects developmental pathways, including NOTCH signaling. Conversely, loss of DNA methylation preferentially occurs in intragenic clusters affecting intronic enhancer regions of genes involved in TGFβ family signaling. Functional experiments prototypically validated the strongly epigenetically regulated inhibitors of TGFβ family signaling SMAD6 and SMAD7 as regulators of EC quiescence. These data establish the transcriptional and epigenetic landscape of vascular quiescence that will serve as a foundation for further mechanistic studies of vascular homeostasis and disease-associated activation.

Single-cell transcriptomics identifies CD44 as a marker and regulator of endothelial to haematopoietic transition

“…Although we observe specific downregulation of Myc in CD44 Low Kit Neg cells, Foxo1 has a similar level of expression in the two endothelial populations (Supplementary Data 5). Recently, a study comparing lung endothelial cells between infant and adult mice showed that higher expression of SMAD6 and SMAD7 was linked with the induction of endothelial cell quiescence typical in adulthood 44 . Interestingly, all the CD44 Low Kit Neg cells co-expressed Smad6 and Smad7 at the single-cell level, suggesting that the quiescent phenotype we observe could also be linked to the co-expression of the two inhibitory Smads.…”

Single-cell transcriptomics identifies CD44 as a new marker and regulator of haematopoietic stem cells development

“…While we observe specific downregulation of Myc in CD44 Low Kit Neg cells, Foxo1 has a similar level of expression in the two endothelial populations. Recently, a study comparing lung endothelial cells between infant to adult mice showed that SMAD6 and SMAD7 higher expression in adult endothelial cells was linked with the induction of endothelial cell quiescence in adulthood 39 . Interestingly, all the CD44 Low Kit Neg cells co-expressed Smad6 and Smad7 at the single-cell level suggesting that the quiescence phenotype we observed could also be linked to the co-expression of the two inhibitory Smads.…”

Apelin signaling drives vascular endothelial cells toward a pro-angiogenic state

“…Toro et al 2010;Herbert et al 2012), little is known about the molecular differences between sprouting and resting ECs(Schlereth et al 2018). By analyzing novel reporter lines for apln and aplnrb expression, we observed high apln expression in tip cells while we could not observe any difference in aplnrb expression between tip and stalk cells (Figure 5 -figure supplement 1).…”