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.
Laboratory of Comparative Carcinogenesis, National Cancer Institute, USA.
C M
CM
Weghorst
G S
GS
Buzard
R J
RJ
Calvert
J E
JE
Hulla
J M
JM
Rice
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