Figure 3.

In vitro differential suppression of podocyte IGF1R activity reveals that partial inhibition is beneficial but near total loss is highly detrimental

(A) Representative Western blot shows >90% reduction of IGF1R protein in NC-IGF1RKD cells but no reduction of IR protein expression. Bar graphs show densitometry expressed as the mean fold change +/− SEM, t-test, ∗∗∗∗p < 0.0001, n = 18 independent experiments.

(B) Phosphorylation of AKT and p44/42MAPK in response to acute IGF1 stimulation at 10 ng and 100 ng/mL for 10 min was significantly reduced in NC-IGF1RKD podocytes. Data are expressed as the mean ± SEM, one-way ANOVA with Tukey’s multiple comparison test, ∗∗p < 0.005, n = 3 independent experiments.

(C) Western blot shows that IGF1R expression is reduced by ∼70% in wild-type podocytes exposed to 100 nM picropodophyllin for 24 h. Data are expressed as the mean ± SEM, t-test, ∗p < 0.05, n = 3 independent experiments. No significant change in IR expression was observed.

(D) Western blot shows the phosphorylation of AKT and p44/42MAPK in response to acute IGF1 stimulation at 10 ng and 100 ng/mL for 10 min in podocytes exposed to 100 nM picropodophyllin for 24 h. Data expressed as the mean ± SEM, ∗p < 0.05, n = 3 independent experiments.

(E) ∼50% of NC-IGF1RKD cells survive 7 days after gene excision. Treatment of wild-type podocytes with 100 nM picropodophyllin for 24 h has no effect on cell survival. Data are expressed as the mean ± SEM, t-test, ∗∗p < 0.005, n = 3–4 independent experiments.

See also Figures S5 and S6.