Figure 1.

Effects of plasma and sera from patients with recurrent FSGS on TRPC6 and podocin in immortalized podocytes. (a) Experiments using plasma from patient 101 sampled during a relapse of recurrent FSGS and later, after remission was achieved following plasma exchange. A representative immunoblot shows total podocin abundance in immortalized mouse podocytes cultured for 24 hr with media containing 2% plasma from 101 taken during relapse and remission, as indicated, as well as in podocytes grown in normal media. Note reduction in total podocin abundance in podocytes cultured with plasma from 101 in relapse. Plasma from 101 taken after remission does not have this activity. This representative immunoblot is shown above bar graph summarizing densitometric analysis of three repetitions of this experiment, presented as mean ± SD of podocin relative to actin. Asterisk indicates P < 0.05 compared to control. (b) Plasma from 101 in relapse also caused marked increase in steady-state cell surface abundance of TRPC6 channels in podocytes as measured by cell-surface biotinylation assays. Bar graph (mean ± SD) summarizes three repetitions of this experiment. Activity is reduced in plasma taken from 101 after remission was achieved. (c) Serum from two other recurrent FSGS patients (048 and 054) caused a reduction in total podocin and an increase in steady-state surface TRPC6. Representative assays are shown to left, and bar graph summaries of three repetitions of these experiments are shown to the right (mean ± SD). Podocytes were treated with media containing 10% of these sera for 24 hr. Asterisks indicate P < 0.05 by Bonferroni t-test.