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Molecular characterization of the first non-mammalian p73 cDNA
A Bhaskaran1, D May, M Rand-Weaver
1Department of Biological Sciences, Brunel University, Uxbridge, Middlesex, UK.
Abstract:
The p53 gene is believed to be mutated or deficient in over 50% of human tumours, and is therefore considered to be instrumental in the process of carcinogenesis. Recently in humans, homologues of p53 (such as p73 and p63) have been isolated. In our studies in fish, we have been isolating tumour suppressor genes with a view to their potential use to study genotoxins in the aquatic environment. In this paper, we report the characterisation of the first non-mammalian p73 cDNA, isolated from barbel (Barbus barbus), a freshwater cyprinid fish indigenous to UK rivers. The deduced barbel p73 amino acid sequence has a high homology with human p73 alpha: the proteins are 641 and 636 aa in length, respectively, and there is a 72% identity over the entire sequence length of the protein (over 90% in the putative DNA binding domain). The level of conservancy for p73 is considerably higher across class (from man to fish), than for p53 and it may therefore have particular value in studies on environmental mutagenesis. Northern analysis showed expression of three p73 mRNA transcripts/homologues. The patterns of p73 tissue expression in the barbel differed from the expression of p53 mRNA, suggesting specific functional roles for the two genes.
Insights
Researchers characterized the first non-mammalian p73 gene in barbel fish. This tumor suppressor gene shows high homology to human p73 and may be valuable for environmental mutagenesis studies.
Area of Science:
- Molecular Biology
- Environmental Toxicology
- Genetics
Background:
- The p53 gene is crucial in human carcinogenesis, with mutations found in over 50% of tumors.
- Homologues of p53, such as p73 and p63, have been identified in humans.
- Tumor suppressor genes are being isolated in fish for aquatic environmental genotoxin studies.
Purpose of the Study:
- To characterize the first non-mammalian p73 cDNA from barbel (Barbus barbus).
- To assess the potential of fish p73 in environmental mutagenesis research.
Main Methods:
- Isolation and characterization of p73 cDNA from barbel fish.
- Amino acid sequence homology analysis with human p73 alpha.
- Northern analysis to study p73 mRNA expression patterns.
Main Results:
- The first non-mammalian p73 cDNA was isolated from barbel fish.
- Barbel p73 shows high homology (72% identity) to human p73 alpha, particularly in the DNA binding domain (>90%).
- Northern analysis revealed three p73 mRNA transcripts with distinct tissue expression patterns compared to p53.
Conclusions:
- The high evolutionary conservancy of p73 across species suggests its importance.
- Barbel p73 may serve as a valuable tool for studying environmental mutagens.
- Differential expression patterns indicate specific functional roles for p73 and p53 in barbel.