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Tissue-specific expression of p53 in transgenic mice is regulated by intron sequences
1Department of Molecular Genetics, University of Texas M. D. Anderson Cancer Center, Houston.
Abstract:
Transgenic mice were produced harboring the p53 murine cDNA clone regulated by the SV40 enhancer-promoter region 5' to the cDNA and the small t antigen splice sites, and poly(A) addition signals 3' to the cDNA. This construction was not expressed in these mice. The presence of several murine p53 introns in the cDNA, however, permitted expression of the transgene mRNA in several tissues of transgenic mice. The insertion of intron 4 led to the preferential expression of the transgene mRNA in spleen cells, where the endogenous p53 gene is also expressed at high levels. While intron 4 promoted high levels of p53 mRNA expression in a tissue-preferred manner in transgenic mice, there was no evidence that intron 4 could act as an enhancer of transcription in cell culture or in transgenic animals. The presence of some p53 introns appears to be critical for the regulation of this gene in vivo.
Insights
Transgenic mice with a p53 cDNA construct showed no expression. However, including p53 introns, particularly intron 4, enabled transgene mRNA expression, especially in spleen cells.
Area of Science:
- Molecular Biology
- Genetics
- Immunology
Background:
- The p53 gene is a critical tumor suppressor involved in cellular responses to stress.
- Understanding the regulation of p53 gene expression is crucial for cancer research.
Purpose of the Study:
- To investigate the role of murine p53 introns in transgene expression in vivo.
- To determine if intron 4 influences tissue-specific expression of p53.
Main Methods:
- Generation of transgenic mice containing a p53 cDNA construct with SV40 regulatory elements.
- Analysis of transgene mRNA expression in various tissues of the transgenic mice.
- Evaluation of intron 4's effect on p53 mRNA levels and tissue preference.
Main Results:
- The p53 cDNA construct alone was not expressed in transgenic mice.
- The inclusion of murine p53 introns facilitated transgene mRNA expression in multiple tissues.
- Intron 4 insertion led to preferential p53 mRNA expression in spleen cells, mirroring endogenous p53 expression patterns.
- Intron 4 did not function as a transcriptional enhancer in cell culture or in vivo.
Conclusions:
- Murine p53 introns are essential for the in vivo expression of the p53 transgene.
- Intron 4 plays a significant role in regulating p53 mRNA levels and directing tissue-specific expression, particularly in the spleen.
- These findings highlight the importance of intronic sequences in the post-transcriptional regulation of the p53 gene.