Fig. 1: Characterization of TRPML3 expression in the lungs using single-cell transcriptomics and a Trpml3^{IRES-Cre/eR26-τGFP} reporter mouse model.

a Cartoon showing the breeding strategy to obtain Trpml3^{IRES-Cre/eR26-τGFP} mice. b Immunofluorescence images using antibodies against different cell markers (red) in 10 µm lung cryosections from transcardially perfused (4% PFA) Trpml3^{IRES-Cre/eR26-τGFP} mice. TRPML3 expression were visually detected in MΦ, T-cells, B-cells, AT2-cells, and Killer T-cells by colocalization analysis with the respective marker. c Quantification of data as shown in b. Percentage of cell type expressing TRPML3 was determined in five randomly chosen zoom-in sections, each (mean ± SEM). d, f FACS analysis of lung tissue and BAL of Trpml3^{IRES-Cre/eR26-τGFP} mice. Shown in d is the gating strategy used to identify TRPML3 + immune cells in the lungs. Further details are provided in the Methods section. Gating strategy and dot plots revealed TRPML3 being expressed mostly in AMΦ in the lung. e Quantitative analysis based on dot plots shown in d. Bar and pie charts show that the highest percentage of GFP + ( = TRPML3+) cells in the lung tissue corresponds to MΦ (71,58%; mean ± SEM, collected from 5 Trpml3^{IRES-Cre/eR26-τGFP} mice). f Gating strategy used to identify TRPML3+ cells in BAL isolated from Trpml3^{IRES-Cre/eR26-τGFP} mice. g Quantitative analysis based on dot plots as shown in f. Bar and pie charts show that the highest percentage of GFP + ( = TRPML3+) cells in the BAL corresponds to MΦ (97.5%; mean ± SEM, collected from 4 Trpml3^{IRES-Cre/eR26-τGFP} mice). h Transcriptomics data of single-cell suspensions from whole WT mouse lungs. Dot plot shows the percentage of cells expressing Mcoln3 using dot size and the average expression level of Mcoln3 based on the unique molecular identifier (UMI) counts. Mcoln3 expression was determined in 32 different cell types. Source data are provided as a Source Data file.