Figure 2.

Islets of extreme obese-diabetic mice reveal massive β-cell dedifferentiation. A, Experimental design of islet scRNA-seq of wildtype and 18- to 20-week-old Sham db/db mice. B, Sham mice showing markedly enhanced body weight (WT, n = 8; Sham, n = 7; p < 0.0001) C, fasting insulin (WT, n = 8; Sham, n = 6; p = 0.0002) and D, fasting blood glucose levels (WT, n = 7; Sham, n = 7; p < 0.0001). Data was analyzed by unpaired student's t-tests. E, UMAP plot of 19,878 endocrine cells from WT and Sham mice. Colours indicate the five main endocrine cell types, and colour tone differentiates between WT (darker tones) and Sham (lighter tones). Numbers highlight the proportion of each cell cluster in WT or Sham, respectively. F–K, Violin plots indicating gene expression of selected β-cell maturity (Ins1, Mafa, Slc2a2) and dedifferentiation (Aldh1a3, Gast, Gc) markers, highlighting key differences between WT and Sham β-cells. Violin plots show the distribution of expression as a kernel density estimate (kde) fit. Points within the violin indicate individual cell points. L, Changes in gene expression of major markers of β-cell identity, function, dedifferentiation and immaturity along a diffusion trajectory path from WT to Sham. Cells are ordered using a random-walk–based distance metric computed using diffusion pseudotime (DPT). A starting point or root cell is randomly selected within the WT β-cells and cell transition from the origin is studied thereafter. Expression shown is the running average along the inferred trajectory, scaled to the maximum observed level per gene. Smaller clusters were removed to ensure smooth transition. M–P, Immunohistochemical analysis of Slc2a2, MafA, UCN3, Insulin and Aldh1a3 in β-cells of WT and Sham mice at study end. Scale is 50 μm. All data are presented as mean ± s.e.m.