Figure 1.

Creation of Ern1^S724Aknock-in mutant mouse model.A, schematic illustration of the gene targeting strategy for creating Ern1^S724A knock-in mutant line. The targeting vector contains exon 17 in which the Ser (S, AGT) residue at 724 was substituted with Ala (A, GCT) in the mouse Ern1 gene, and the FRT-flanked Neomycin (Neo) cassette was subsequently removed by Flipper recombinase. B, photograph of Ern1^S724A/S724A mice and Ern1^WT/WT littermates and their body weight when maintained on a normal chow diet at the indicated ages (n = 4 per group). C, immunoblot analysis of IRE1α phosphorylation at Ser⁷²⁴ in primary hepatocytes from Ern1^WT/WT control and Ern1^S724A/S724A mice. Hepatocytes were treated with the chemical ER stressors tunicamycin (Tm, 10 μg/ml) for 4 h or thapsigargin (Tg, 1 μM) for 2 h. The asterisk indicates a nonspecific band detected by anti–phospho-IRE1α antibody. Tubulin was used as the loading control. ER, endoplasmic reticulum; IRE1α, inositol-requiring enzyme 1α.