Myocardial cellular gene expression during pressure overload: evidence for transient partial endothelial to mesenchymal transition [Ribo-seq]

Pathological processes underlying pressure overload triggered heart failure were mainly analyzed from a cardiomyocyte centric view. To identify new cellular mechanisms, we isolated cardiomyocytes, endothelial cells and fibroblasts as most abundant cardiac cell types from mice in the subacute and chronic stages of pressure overload (by transverse aortic constriction, TAC) and performed RNA-sequencing. We detected highly cell-type specific transcriptional responses with characteristic time courses and active intercellular communication, especially early after TAC. We focused on endothelial cells, and single-cell sequencing in this population showed enhanced expression of collagens and inflammatory mediators at this stage. Importantly, these endothelial transcriptional changes were transduced to the translational level as shown by Ribo-Tag sequencing and verification of collagen protein production by cardiac endothelial cells. In conclusion, we provide a resource of cardiac cellular gene expression in pressure overload and reveal the induction of collagens by endothelial cells as potential therapeutic target. Overall design: Ribo-tag mice were crossed with Cdh5-CreERT2 mice expressing the Cre recombinase under the control of the Cadherin 5 (Cdh5) promoter (Cdh5-CreERT2:Ribo-tag). At 9 weeks of age, male mice underwent transverse aortic constriction or sham operation