Fig 1: Identification of key ligand–receptor pairs associated with diabetic myocardial fibrosis in the fibroblasts.(A) Heatmap showing the pairs of highly expressed fibroblast receptors and upregulated ligands in each cell type in the diabetic hearts. (B) PPI network showing the interactions of the upregulated genes in the fibroblasts. The circle size represents the protein node degree in the network. Volcano plots of the DEGs in the heart tissues of high-fat diet (HFD)/streptozotocin (STZ)-treated and control mice. Pdgfa, Pdgfb, Pdgfc, and Pdgfd expression in the endothelial cells (C) and macrophages (D) are highlighted. (E) Volcano plots of the DEGs in the hearts of the HFD/STZ-treated and control mice. Efemp1 expression in the epicardial cells is highlighted. (F) Representative immunofluorescence images of p-Pdgfra in the heart tissues of the HFD/STZ-treated mice with or without Ima treatment (n = 6 mice per group), scale bar = 40 µm. Bar plots showing mRNA expression of Col1a1 (G) and Col3a1 (H) in the heart tissues of the HFD/STZ-treated mice with or without Ima treatment (n = 6 mice per group; mean ± SEM; **p < 0.01; ***p < 0.001). (I) Representative images of Masson dye-stained heart sections from the groups indicated showing the extent of collagen deposition (n = 6 mice per group), scale bar = 20 µm. Ima, imatinib mesylate; SEM, standard error of mean. The details of the cognate ligands of Egfr and Pdgfra are listed in Supplementary file 13 and Supplementary file 14, respectively. Figure 3—source data 1.Source data for CT values of Col1a1 used for Figure 3G. Figure 3—source data 2.Source data for CT values of Col3a1 used for Figure 3H.