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. Author manuscript; available in PMC: 2020 Dec 1.
Published in final edited form as: Kidney Int. 2019 Aug 1;96(6):1303–1307. doi: 10.1016/j.kint.2019.07.010

Figure 2.

Figure 2

Toxicity in inducible T-Rex 293 cells stably expressing APOL1 of different haplotypes. APOL1 expression was induced by addition of tetracycline. Cytotoxicity was measured using either the cytotoxicity-to-viability ratio (a-c) or by MTT assay (d-e). Each cell line’s data are normalized to the corresponding no-tetracycline control. Similar APOL1 expression levels among cell lines are demonstrated in Supplementary Figures S2 (mRNA) and S3 (protein); Supplementary Figure S3 demonstrates that APOL1 transgene expression does not activate endogenous APOL1 expression.

a) Risk variants G1 and G2 demonstrate higher cytotoxicity than non-risk variants Ref and G0. P<0.001 for risk variants G1 and G2 vs. non-risk variants Ref and G0.

b) G1 and G2 mutations on a Ref haplotype background demonstrate reduced cytotoxicity compared to naturally-occurring G1 and G2. P<0.001 for G1 vs. Ref G1. P<0.01 for G2 vs. Ref G2.

c) G1 or G2 mutations on the N264K haplotype background shows no difference in cytotoxicity as compared to G0 N264K. P<0.001 for G1 vs G1 N264K and for G2 vs. G2 N264K.

d) After 24 hours of tetracycline induction, cells expressing G1 or G2 exhibit the lowest viability, with near-complete rescue by engineering G1 and G2 into Ref or G0 N264K backgrounds. P<0.001 for G1 vs Ref G1 and G1 N264K. P<0.001 for G2 vs. Ref G2 and G2 N264K.

e) After 48 hours of tetracycline induction, cells expressing G1 and G2 exhibit more toxicity than G1 and G2 on the Ref or G0 N264K haplotype backgrounds. P<0.001 for G1 vs. Ref G1 and G1 N264K. P<0.001 for G2 vs. Ref G2 and G2 N264K.