Fig. 4: MAFB controls pancreatic endocrine cell lineage specification.

a UMAP projections of integrated MAFB+/+ and −/− transcriptomes, color-coded by genotype (left) and cell populations (right). b Scatter plot showing the average gene expression (log scale) for MAFB+/+ and −/− cells at the β-like cell stage. Differentially expressed genes (log fold change >0.5, adjusted P value <0.1) between MAFB+/+ and −/− cells are shown in red. Significance was calculated using the MAST test and P values were adjusted for multiple testing using the Benjamini–Hochberg method. The top FIVE up- and downregulated genes are indicated. c qPCR analysis showing mRNA levels of islet hormones (INS, GCG, SST, PPY, and GHRL) at the β-cell stage by. P values by unpaired two-tailed t-test were *P < 0.05 and ***P < 0.001. d–f Representative FC plots depicting d C-PEP+ and CHGA+ cells (n = 5, biologically independent samples), e C-PEP+ and GCG+ cells (n = 5, biologically independent samples), and f C-PEP+ and SST+ cells (n = 4, biologically independent samples) and respective quantification at the β-like cell stage. g Representative IF images from four independent experiments at the β-cell stage of differentiation depicting GCG, SST, NKX6.1, and DAPI. Scale bars, 50 μm. h Western blotting for SST protein (14 kDa) expression at the β-cell stage. GAPDH (38 kDa) was used as a loading control (n = 2 biologically independent MAFB+/+ samples and n = 3, biologically independent samples for MAFB + /− and −/−). i Representative FC plots depicting the percentages of C-PEP + PPY+ cells and quantification at the β-like cell stage (n = 4 for MAFB+/+ and n = 3 for MAFB−/−, biologically independent samples). P values by unpaired two-tailed t-test were ****P < 0.0001. j Representative IF images from four independent experiments depicting SST and HHEX (upper panel) and PPY and GCG (lower panel) and DAPI. Scale bars, 50 μm. P values by one-way ANOVA followed by Dunnett’s multiple comparisons test were *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Data are presented as individual biological replicates, representing the mean ± SD. N numbers indicated in Supplementary Fig. 2a, b.