Translation of human [DELTA]133p53 mRNA and its targeting by antisense oligonucleotides complementary to the 5'-terminal region of this mRNA

• Published in: PloS one 2021-09, Vol.16 (9), p.e0256938
• Main Authors: Zydowicz-Machtel, Paulina, Dutkiewicz, Mariola, Swiatkowska, Agata, Gurda-Wozna, Dorota, Ciesiolka, Jerzy
• Format: Article
• Language: English
• Subjects: Analysis; Genetic translation; Messenger RNA; Proteins
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0256938

The p53 protein is expressed as at least twelve protein isoforms. Within intron 4 of the human TP53 gene, a P2 transcription initiation site is located and this transcript encodes two p53 isoforms: [DELTA]133p53 and [DELTA]160p53. Here, the secondary structure of the 5'-terminal region of P2-initiated mRNA was characterized by means of the SHAPE and Pb.sup.2+ -induced cleavage methods and for the first time, a secondary structure model of this region was proposed. Surprisingly, only [DELTA]133p53 isoform was synthetized in vitro from the P2-initiated p53 mRNA while translation from both initiation codons occurred after the transfection of vector-encoded model mRNA to HCT116 cells. Interestingly, translation performed in the presence of the cap analogue suggested that the cap-independent process contributes to the translation of P2-initiated p53 mRNA. Subsequently, several antisense oligonucleotides targeting the 5'-terminal region of P2-initiated p53 mRNA were designed. The selected oligomers were applied in in vitro translation assays as well as in cell lines and their impact on the [DELTA]133p53 synthesis and on cell viability was investigated. The results show that these oligomers are attractive tools in the modulation of the translation of P2-initiated p53 mRNA through attacking the 5' terminus of the transcript. Since cell proliferation is also reduced by antisense oligomers that lower the level of [DELTA]133p53, this demonstrates an involvement of this isoform in tumorigenesis.