Length and secondary structure of the 5′ non-coding regions of mouse p53 mRNA transcripts - mouse as a model organism for p53 gene expression studies

Abstract

Transcription initiation sites of Trp53 gene in mice were determined using the 5′RACE method. Based on sequence alignment of the 5′-terminal regions of p53 mRNA in mammals, the site for the most abundant transcript turned out to be essentially identical with that determined for human TP53 gene and slightly differed for the longest transcripts, in mice and humans. Secondary structures of the 5′-terminal regions of the shorter, most abundant and the longest mouse transcripts were determined in vitro and the shorter transcript was also mapped in transfected mouse cells. For the first time, secondary structure models of the 5′ terminus of two mouse p53 mRNAs were proposed. Comparing these models with the conservativeness of the nucleotide sequence of the 5′-terminal region of mRNA in mouse and other mammals, the possible function of the selected structural domains of this region was discussed. To elucidate the translation mechanisms, the two studied mRNAs were translated in the presence of an increasing concentration of the cap analog. For the longest transcript, the data suggested that IRES element(s) was/were involved in translation initiation. Additionally, changes in p53 synthesis under genotoxic and endoplasmic reticulum stress conditions in mouse cells were analyzed.

Translational Control in p53 Expression: The Role of 5′-Terminal Region of p53 mRNA

“…This is in line with earlier observations concerning the identification of mouse transcription promoter regions [37]. Interestingly, the comparison of the 5′-terminal sequences of mouse mRNA-122 and of human P1-initiated p53 mRNA revealed that the transcripts differ only by a single nucleotide in spite of a substantially different length of their 5′UTRs [36]. We also detected longer transcripts, termed as mRNA-247, which comprise the 5′UTR region of approximately 247 nucleotides in length.…”

“…Recently, we determined transcription initiation sites for the mouse Trp53 gene by the 5′RACE method [36]. The most frequent transcripts isolated from the embryos, liver and thymus, termed as mRNA-122, contain the 5′UTR comprising approximately 122 nucleotides.…”

“…We also detected longer transcripts, termed as mRNA-247, which comprise the 5′UTR region of approximately 247 nucleotides in length. These transcripts have been observed in mouse embryos, and additionally in the brain, heart and spinal cord tissues [36].…”

“…The secondary structure model of the 5′-terminus of human p53 mRNA was compared with the nucleotide conservation of this region in various organisms (Figure 1). This comparison was based on the earlier presented alignment of the 5′-terminal regions of p53 mRNAs derived from 11 different species (Figure 2 in [36]). This data showed which structural elements are mostly conserved due to the important role in the folding of this RNA region or due to functional interactions with other factors, likely proteins.…”

“…Finally, nucleotides of the G56–C169 hairpin domain, which are characteristic of both 5′UTRs of P1-Δ40p53 and P0-Δ40p53 mRNAs, were less conserved. Moreover, in the mouse p53 mRNA, this hairpin was shorter and its bottom segment was unfolded [36]. The 5′-proximal stretch of the unfolded segment formed another hairpin (see the inset in Figure 2), while the 3′-proximal stretch remained single-stranded.…”