Cloning and sequence of a processed p53 pseudogene from rat: a potential source of false 'mutations' in PCR fragments of tumor DNA.
We describe here the nucleotide (nt) sequence of a p53 processed pseudogene (psi-gene) from the normal F344 rat genome. Exon-derived primers were utilized to amplify and clone a 1447-bp polymerase chain reaction (PCR) product corresponding to the coding regions of exons 2-11 of the functional gene. This psi-gene is a cDNA-like sequence possessing 87% homology with the functional rat p53. We have also partially characterized two additional and distinctly different putative rat p53 psi-genes, focussing on the sequences surrounding the reported rat p53 mutational hot spots of codons 202R and 211R within exon 6/7. Each of these three psi-gene sequences contained various single- and/or double-nt substitutions, small deletions and insertions that distinguish them from p53. One substitution, 211R CGG-->CAG, found both in the cloned psi-gene and in one of the partially characterized, putative psi-genes, corresponded precisely with the sequence that has been reported as a mutation at one of the hot spots. Co-amplification of one or more of the p53 psi-genes with portions of the functional p53 is likely, if exon-based primers are utilized for PCR amplification of rat p53. Consequently, psi-gene sequences are potential sources of sequence variations that can be misidentified as somatic cell mutations by direct sequencing of inappropriately generated PCR products.
Weghorst
C M
CM
Laboratory of Comparative Carcinogenesis, National Cancer Institute, USA.
Buzard
G S
GS
Calvert
R J
RJ
Hulla
J E
JE
Rice
J M
JM
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D004273:DNA, Neoplasm / Q000235:genetics; D005091:Exons; D016158:Genes, p53; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D009374:Neoplasms, Experimental / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011544:Pseudogenes; D051381:Rats
D017931:DNA Primers; D004273:DNA, Neoplasm