Fig. 2

rMSA prevented islet atrophy and β-cell apoptosis by reducing FFA uptake. A–C Representative images of H&E staining of pancreatic slices from the db/db mice (n = 7–10 per group) and WT mice (n = 5 per group) respectively treated with saline or rMSA for 9 weeks (A). Dotted boxes indicate the location of the islets, with the corresponding ×10 zoom in the upper right corner of each ×1 image. Scale bars in the ×1 images represent 1 mm, and those in the ×10 images represent 100 μm. The relative size (B) and proportion of islets to the pancreas (C) were calculated respectively. D Representative images of IF staining for insulin and TUNEL assays in pancreases of the db/db mice treated with saline (n = 10) or rMSA (n = 6) for 9 weeks. Insulin staining is shown in red; DAPI-stained nuclei are shown in blue; TUNEL is shown in green. Scale bars represent 50 μm. E The percentage of TUNEL and insulin double-positive cells to all insulin-positive cells in the islets of the db/db mice treated with saline or rMSA for 9 weeks, corresponding to the representative images (D). F Flow cytometry analysis showing the relative fluorescent intensity in MIN6 cells under the indicated molar ratios of BODIPY™ FL C12 to rMSA (n = 3 per group). G FFA uptake assays showed the effects of rMSA at different concentrations (n = 3 per group) on FFA uptake rate, which was represented as the concentration of FFA in the medium at different time points. The basal concentration of FFA under each treatment was 0.2 mM. H Heat map showing the PA (0 or 0.2 mM) and rMSA (0 or 300 μM) treatments for 16 h on the intracellular lipidome of MIN6 cells (n = 3 per group). I Western blot showing the protein levels of CC3 and CHOP in the MIN6 cells treated with vehicle or PA (0.2 mM) with rMSA at indicated concentrations. β-Tubulin was used as the internal reference. Data were analyzed by two-way ANOVA with repeated measures (G) and unpaired t-tests (B, C, E, and F). Data are expressed as mean ± s.e.m. *p < 0.05, **p < 0.01, ****p < 0.0001