Figure 5. CD81 regulates SAMHD1 expression.

a) Primary T lymphoblasts transfected with control or CD81 siRNA, and Hela/R5 cells transfected or not with CRISPR/Cas9-CD81 were lysed and immunoblotted for CD81, SAMHD1 and phosphorylated SAMHD1. Tubulin or cofilin were used as loading controls. Blots are from representative experiments out of 2 (lymphoblasts) and 3 (Hela/R5). Signal ratios in relation to the loading controls are depicted. Arrows indicate the SAMHD1 band that has the predicted molecular weight (~70kDa). b) Hela/R5 cells transfected or not with CRISPR/Cas9-CD81 were fixed, permeabilized, immunolabelled for SAMHD1 and CD81, and analysed by flow cytometry. Histograms show a representative experiment out of 3. The negative control corresponds to cells stained only with secondary antibody. c-d) CRISPR/Cas9-CD81 or control Hela/R5 cells were treated for 6h with the vehicle or with the depicted concentrations of (c) MG132 or (d) NH₄Cl. Cells were lysed and immunoblotted for SAMHD1, and ERM as loading control. Graph shows the mean fold change ± SEM of SAMHD1/ERM signal ratio from (c) 3 or (d) 2 independent experiments analysed by one-way ANOVA with Bonferroni’s post-test.