Figure 2. PolyI:C induces the expression of SOX9, HES1, and MYC in human β cells.

(A–C) EndoC-βH1 cells were either mock transfected (CTRL) or transfected with PolyI:C and analyzed 24 hours later (n = 3). (A and B) Heatmap from global transcriptomic analysis and RT-qPCR data represent induced genes. (C) Western blot analysis of SOX9 expression (n = 3; n1, n2, and n3 correspond to 3 independent experiments). (D) Primary human islet cells were dissociated and either mock transfected (CTRL) or transfected with PolyI:C and analyzed 24 hours later by immunocytochemistry. Nuclei are stained with Hoechst 33342 stain (blue), insulin is in red, and SOX9 is in green. Arrowheads point to insulin⁺ (INS⁺) cells that stain positive for SOX9 following PolyI:C treatment. Scale bars: 25 μm. The inset shows a higher-magnification image (×2.1 magnification; scale bar: 5 μm). Representative images of 4 independent experiments. (E–G) EndoC-βH1 cells were infected with enteroviruses at 5 × 10⁴ TCID₅₀ and harvested 24 hours later. (E) Western blot analysis of VP1 expression (n = 3). (F and G) qPCR analyses of SOX9, MYC, and HES1 expression (n = 3). (H) Human islets were infected with enteroviruses at 5 × 10⁷ TCID₅₀ and harvested 24 hours later. Western blot analyses of VP1 and SOX9 expression are shown (representative images of 3 independent experiments). Data from RT-qPCR, Western blots, and immunofluorescence represent the mean ± SD of 3 independent experiments. *P < 0.05, **P < 0.01, and ***P < 0.001 relative to control by Student’s t test. CVB5-F, coxsackievirus strain B5 Faulkner; EV-9 B, echovirus 9 Barty.