Journal: Cancer Research
Article Title: The Prolonged Half-Life of the p53 Missense Variant R248Q Promotes Accumulation and Heterotetramer Formation with Wild-Type p53 to Exert the Dominant-Negative Effect
doi: 10.1158/0008-5472.CAN-24-1136
Figure Lengend Snippet: Heterotetramers consisting of R248Q and WT p53 are transcriptionally inactive, but overexpression of WT p53 can overcome the DNE of R248Q. A, MOLM13- TP53 isogenic cell lines were treated with DMSO or 100 nmol/L Dauno for 3 hours, followed by collection of whole-cell protein lysates by using IGEPAL lysis buffer. Lysates were fixed with 0.03% glutaraldehyde and subsequently separated on a polyacrylamide gel under nonreducing conditions. The PVDF membrane was immunoblotted for p53 ( n = 3 independent experiments; one representative blot is shown). B, MOLM13- TP53 null or K562- TP53 null AML cell lines lentivirally transduced to stably express full-length R248Q, tetramerization-deficient R248Q (R248Q-L344A), or dimerization-deficient R248Q (R248Q-L344P or R248Q-OD lacking the OD of p53) were treated for 3 hours with either DMSO or 100 nmol/L Dauno. Glutaraldehyde-fixed whole-cell protein lysates were separated on a polyacrylamide gel and immunoblotted for p53 ( n = 3 independent experiments; representative blots are shown). C, Experimental schematic depicting the general principle of the flow cytometry–based FRET assay in K562- TP53 null AML cells. For experimental details, please refer to the Materials and Methods. D, Representative FACS plots showing results of the FRET assay in K562- TP53 null AML cells for the interaction between WT monomers (top), or WT and R248Q monomers (bottom). FRET donor and acceptor plasmids encoding p53 WT or R248Q variants either oligomerization-proficient (WT) or -deficient (WT-L344A, WT-L344P, or WT-OD) were co-electroporated into K562- TP53 null AML cells, followed by FRET measurement (FRET fluorescence measured using the 525/50-nm detector). E, Pooled results of the FRET assays in K562- TP53 null AML cells ( n = 3 independent experiments). Bar graphs represent averages. Error bars, SD. ***, P ≤ 0.001; ****, P ≤ 0.0001, one-way ANOVA, Tukey multiple comparison. F, Experimental schematic and pooled results of the transcriptional reporter assay in K562- TP53 null -p21-GFP cells electroporated with plasmids encoding oligomerization-proficient or -deficient WT p53 variants ( n = 3 independent experiments). Bar graphs represent averages. Error bars, SEM. *, P ≤ 0.05; **, P ≤ 0.01; ****, P ≤ 0.0001, one-way ANOVA, Tukey multiple comparison. G, Experimental schematic and pooled results of the transcriptional reporter assay in K562- TP53 WT -p21-GFP cells electroporated with pRK5 plasmids encoding oligomerization-proficient or -deficient R248Q p53 variants ( n = 3 independent experiments). Bar graphs represent averages. Error bars, SEM. **, P ≤ 0.01; ****, P ≤ 0.0001, one-way ANOVA, Tukey multiple comparison. H, Quantification of the bioluminescent signal (i.e., total flux per second) for each group of mice 12 and 16 days after sublethal irradiation and subsequent injection with MOLM13- TP53 +/− -GFP-luciferase AML cell lines overexpressing either R248Q (WT + R248Q) or oligomerization-deficient R248Q-L344P (WT + R248Q-L344P). Following, mice were treated with idasanutlin (Ida, 25 mg/kg of BW per day) or vehicle (Veh) for seven consecutive days ( n = 7 animals per group). Symbols represent averages. Error bars, SD. ***, P ≤ 0.001, Mann–Whitney test. I, Survival analysis of NSG mice engrafted with MOLM13- TP53 +/− -GFP-luciferase AML cell lines overexpressing either R248Q (WT + R248Q) or R248Q-L344P (WT + R248Q-L344P) and treated with idasanutlin (25 mg/kg of BW per day) or vehicle for seven consecutive days ( n = 7 animals per group). ****, P ≤ 0.0001, Kaplan–Meier simple survival analysis. J, Experimental schematic and pooled results of the transcriptional reporter assay in K562- TP53 R248Q -p21-GFP cells electroporated with the pRK5 plasmid encoding oligomerization-proficient WT p53 variant ( n = 3 independent experiments). Bar graphs represent averages. Error bars, SEM. ****, P ≤ 0.0001, Welch t test. CNTR, control; FRET-Acc, FRET acceptor; FRET-Don, FRET donor. ns, nonsignificant.
Article Snippet: Afterward, mutagenized p53 variants were amplified and cloned into Cilantro 2 (a great gift from Benjamin Ebert, Addgene plasmid #74450, http://n2t.net/addgene:74450 , q RRID: Addgene_74450) while cutting out the included enhanced green fluorescent protein (EGFP) sequence.
Techniques: Over Expression, Lysis, Membrane, Stable Transfection, Flow Cytometry, Fluorescence, Comparison, Reporter Assay, Irradiation, Injection, Luciferase, MANN-WHITNEY, Plasmid Preparation, Variant Assay, Control