Figure 5

Gene expression of components of the renin–angiotensin system point towards alveolar cells role. (a) Schematic representing the main players and steps of the angiotensin system, also known as the renin–angiotensin system (RAS). ACE2 catalyzes the conversion of angiotensin I to angiotensin 1–9, and of angiotensin II into inactive angiotensin 1–7. Renin catalyzes the conversion of angiotensinogen (AGT) into angiotensin I. ACE catalyzes the conversion of angiotensin I into angiotensin II, which binds to its receptor AGTR1. 1–5 Visualization of gene expression in dbMAP embeddings of the lung atlas. 1 ACE2 expression is restricted to alveolar cells. 2 AGT is expressed in fibroblasts and smooth muscle cells. 3 REN expression is restricted to alveolar cells. 4 ACE expression is selective to endothelial cells and macrophages. 5 AGTR1 expression is selective to fibroblasts and smooth muscle cells. (b) Dot plot visualization of the expression of genes involved in the angiotensin system in the lung atlas cell types. ACE2 expression is restricted to alveolar cell clusters, similarly to REN, which is virtually absent from remaining clusters. AGT is highly expressed in fibroblasts and muscle, albeit being lowly expressed in a large portion of cells from other clusters. ACE is preferentially expressed in endothelial cells and macrophage clusters. AGTR1 is highly expressed in smooth muscle cells and fibroblasts, and lowly expressed in macrophages and alveolar cells.