Fig. 4: Mitigation of SEC Gene Expression Under ER Stress in Type 1 Diabetes Islets.

A Human islets sourced from non-diabetic (non-DM) and Type 1 Diabetes (T1D) donors, incubated for 24 h in Miami medium, with or without the addition of thapsigargin (TG) at a concentration of 250 nM. Created in BioRender. Shibue, K. (2025) https://BioRender.com/7w1qe08. B Heatmap representing the log2 (fold change) of the top differentially expressed genes (DEGs) after TG treatment in non-DM and T1D islets, alongside the SEC family genes originally identified in the CRISPR screen (as depicted in Fig. 1). C, D Volcano plot of genes in non-DM (C) and T1D (D) islets treated with TG. Differential gene expression was assessed using limma with moderated two-sided t tests. Equivalence testing for unchanged genes (fold change < 20%) was performed using two one-sided t tests (TOST). P-values were adjusted for multiple comparisons using the Benjamini-Hochberg FDR correction. E Heatmap of T1D islets treated with TG, TUDCA, and their mixture. Donor numbers (5–7) in the figure correspond to those in Fig. 4B and Supplementary Table 2. F Dot plots of ER stress-related pathways in T1D islets treated with TG, TUDCA, and their mixture. Differential expression was analyzed using limma with linear modeling and moderated two-sided t tests. P-values were adjusted for multiple testing using the Benjamini-Hochberg FDR method. G Gene expressions of SEC family genes, including SEC31A, in T1D islets treated with TG, TUDCA, and their mixture. N = 3 for T1D, each representing an independent biological replicate. Donor numbers (5–7) correspond to those in Fig. 4B and Supplementary Table 2. H SEC31A expression levels expressed as log₂ CPM under control (no treatment), TG, TUDCA, and TG + TUDCA conditions (blue shading reflects expression level: darker blue = higher expression, lighter blue = lower expression). I Immunohistochemistry of non-diabetic human islets treated with media containing TNFα (1000 U/ml), IFN-γ (1000 U/ml), IL-1β (50 U/ml) + IFNγ, and 19 mM glucose was stained with antibodies against insulin (INS), glucagon (GCG), and SEC31A. Treatment time was 24 h. N = 3, each representing an independent biological replicate. Scale:20 μm. For the demographics of donors, see Supplementary Table 2. J Quantification of SEC31A-positive cells shown in (I). Data is presented as mean values ± SEM. (two-tailed Student’s t test). *p < 0.05. Source data are provided as a Source Data file.