Fig. 5

Calpain-dependent PrP solubility and prion conversion in sCJD. a Solubility assay in sCJD brain homogenates (n = 3) in presence of recombinant PrP (rPrP) and in the presence or absence of protein inhibitors and the Calpain inhibitor MDL28170. Quantification of soluble rPrP is shown. b RT-QuIC assay performed in the presence of sCJD brain homogenates (n = 4) as seeding material, previously treated or untreated with recombinant Calpain. Area under the curve (AUC) (left) and Lag Phase (hours) are shown. c RT-QuIC assay from tg340-PRNP129MM brain extracts (n = 3) inoculated with sCJD MM1 previously incubated with increased concentrations of MDL28170. Relative Fluorescence Units (RFU) are shown (d) Co-immunoprecipitation study of Calpain 1 and PrP in the frontal cortex of sCJD MM1 and in the cerebellum of sCJD VV2 cases. Calpain 1 antibody was used for western-blot immunodetection. Control indicates the use a non-specific antibody as immunoprecipitating antibody. Unpaired t-test (95% CI) was used for the comparisons of the two groups. ANOVA test followed by post-test Tukey’s Multiple Comparison Test was used to compare the values from different groups. P values for the comparisons of the three groups are indicated in the figure:*p < 0.05; **p < 0.01; ***p < 0.001