Journal: Oncotarget
Article Title: PRPF8 is important for BRCA1-mediated homologous recombination
doi: 10.18632/oncotarget.21555
Figure Lengend Snippet: A. PRPF8 forms a complex with XAB2. Shown are immunoblot signals for PRPF8 and XAB2 from Flag-immunoprecipitates of U2OS cells transfected with a 3xFlag-XAB2 (3xf-XAB2) expression vector or empty vector (EV). Also shown are immunoblot signals for XAB2, PRPF8, and BRCA1 for U2OS cells immunoprecipitated with antibodies against (α) PRPF8, BRCA1, or control IgG. Also shown are input (Inp) samples used for the immunoprecipitates (IP). B. PRPF8 is important for HDR and SSA to a greater degree than EJ. U2OS cell lines with GFP-based DSB reporter assays were pretreated with siRNAs targeting PRPF8 (siPRPF8-2, siPRPF8-4), XAB2 (siXAB2-4), or a non-targeting control (siCTRL), prior to expression of I-SceI and analysis by flow cytometry. Shown are GFP+ frequencies normalized to the mean of parallel siCTRL-treated samples. * P ≤ 0.0004, N = 6. Also shown are immunoblot signals confirming depletion of PRPF8 by siPRPF8-2 and siPRPF8-4, as well as expression of myc-PRPF8, with an Actin loading control. The panel on the left (comparison of PRPF8 levels in cells treated with siRNA) was an independent experiment and analyzed on a separate immunoblot from the panel on the right (comparison of PRPF8 levels in cells treated with siRNA and transfected with myc-PRPF8 or EV). C. Transient expression of PRPF8 rescues HDR and SSA in cells treated with siPRPF8-2. Reporter assays were performed as in B, except an expression vector for myc-PRPF8 with silent mutations at the siPRPF8-2 targeting sequence (expression shown in B), or EV, were included in the transfection with the I-SceI expression vector. D. PlaB treatment causes a decrease in HDR and SSA, but not EJ, whereas DRB causes a greater defect on HDR vs . either EJ or SSA. U2OS reporter cell lines were treated with non-targeting RNA (siCTRL) as in A, and transfected with an inducible form of I-SceI (I-SceI-GR). The day after transfection, cells were pre-treated (2hr) with PlaB, DRB, or vehicle (DMSO), and then treated overnight with the same small molecules, but also including the I-SceI-GR inducing agent (TA). The cells were cultured for an additional day prior to flow cytometry analysis. Shown are GFP+ frequencies normalized to parallel DMSO-treated wells. * P < 0.0001. N = 6 for DR-GFP and EJ5-GFP. N = 12 for SA-GFP.
Article Snippet: The pCAGGS-myc-PRPF8 expression vector was derived from Origene clone SC116070, and generated with silent mutations at the siPRPF8-2 site, 5’ GCcGAcGGgcTaCAGTAcA.
Techniques: Western Blot, Transfection, Expressing, Plasmid Preparation, Immunoprecipitation, Flow Cytometry, Sequencing, Cell Culture