Journal: bioRxiv
Article Title: Isoform-Specific Activation of p53B and p53C in Response to Nucleolar Stress in Drosophila wing imaginal discs
doi: 10.1101/2025.08.07.669174
Figure Lengend Snippet: (A-B) Schematic representation of the p53 locus (gene ID 2768677) and of the p53 isoforms A, B, C , and E . (B-i), magnification of a common exon with the representation of the region where the primers that capture all p53 isoforms anneal . These primers were used in and will be referred to as “p53 pan”. (C) Schematic representation of the p53A A2 . 3 , p53B 41 . 5 , and p53 A5 . 1 . 4 null mutant alleles. p53A A2 . 3 null line was generated with a deletion of 23bp deletion, and a 7bp insertion spanning from the end of the first exon until the first base of the first intron (in red), generating multiple early STOP codons (Supplementary Figure 2). This deletion also affects the p53C isoform, leading to no production of p53C protein, according to Chakraborty et al. 2022. p53B 41 . 5 null line was generated with a 14bp deletion and a 1bp insertion in the second exon that causes a frameshift and introduces premature stop codons (Supplementary Figure 2). p53 A5 . 1 . 4 null line has a deletion of 3.3 kb, removing the common 3’ coding region (in red). (D) p53A isoform. (D-i and ii), magnification of exons 1 and 2 of p53A and p53A A2 . 3 null isoform, respectively, displaying where the primers designed in this study anneal (in green) and compared to previous primers (in pink). As shown in D-ii, the new primers can also be used to identify p53A in the p53A A2 . 3 null mutant, as the forward primer does not anneal within the deleted region. Conversely, 1 bp of the previous reverse primer (pink) mismatch in the p53A null line. Note that this new set of primers can also capture p53C isoform; therefore, they will be referred to as “p53A/C”. (E) p53B and p53C isoforms. (E- i, ii, and iii), magnification of exons 2 and 3, which are common to both isoforms, showing where the primers designed in this study anneal (in green). Note that the new pair can distinctly capture the p53B isoform, while the old primers (in pink) also capture p53C . Moreover, the new pair is also suitable for studying the p53B null line since the forward primer does not anneal in the deleted region marked in red (E-ii). This pair of primers will be referred to as “p53B”. (F) p53C isoform. (F-i), magnification of the region in exon 2 showing the sequence of 78 bp, from 440 to 518 nucleotides from the beginning of the p53C transcript (in orange), present only in this isoform. Optimized primers for the detection of this isoform are represented in green. This new set of primers will be referred to as “p53C”. (G) Photo of a 2% agarose gel showing qPCR amplified products from RNA extracted from wing imaginal discs from w 1118 third instar larvae using the indicated primers and actin as a control. A single band is visible for each primer pair, indicating the specificity of the new optimized primers.
Article Snippet: After Ponceau staining, the membrane was blocked with 5% non-fat milk in TBS-T. Then the membranes were incubated with primary antibody mouse anti-p53 (1:200, Dmp53 H3, DSHB), and mouse anti-actin (1:1000; DSHB 224-236-1), followed by incubation with HRP-conjugated secondary antibodies (Santa Cruz Biotechnology).
Techniques: Mutagenesis, Generated, Sequencing, Agarose Gel Electrophoresis, Amplification, Control