Figure 3.

The UPR protein levels are similar in WT and COL4A5 mutant iPSCs. (A) Protein expression of the UPR markers Bip, ATF6, p50-ATF6, p-IRE1α, IRE1α, p-PERK, and PERK was measured after reprogramming by western blotting. β-tubulin expression was used as an equal loading control. Representative blotting shows the protein levels of these proteins (Supplementary Figure 1). (B–H) The expression of Bip, ATF6, p50-ATF6, p-IRE1α, IRE1α, p-PERK, and PERK in WT iPSCs, COL4A5 missense mutant iPSCs, COL4A5 splicing iPSCs and COL4A5 frameshifted mutant iPSCs were quantified by densitometric analysis. The protein levels of ER chaperone protein Bip, three ER transducers (ATF6, IRE1α, and PERK) and their activated forms (p50-ATF6, p-IRE1α, and p-PERK) were similar between the WT and mutant samples examined. Data are means ± SEM. n = 3, (WT, control; MM, missense mutation; SM, splicing mutation; FM, frameshift mutation).