TitleSequencing of the rat beta-catenin gene (Ctnnb1) and mutational analysis of liver tumors induced by 2-amino-3-methylimidazo[4,5-f]quinoline.
Publication TypeJournal Article
Year of Publication2002
AuthorsLi Q, Dixon BM, Al-Fageeh M, Blum CA, Dashwood RH
Date Published2002 Jan 23
KeywordsAmino Acid Sequence, Animals, Base Sequence, beta Catenin, Cytoskeletal Proteins, DNA, DNA, Complementary, Exons, Genes, Introns, Liver Neoplasms, Experimental, Male, Molecular Sequence Data, Mutation, Polymorphism, Single-Stranded Conformational, Quinolines, Rats, Rats, Inbred F344, RNA, Messenger, Sequence Analysis, DNA, Trans-Activators

beta-Catenin, a protein that functions in cadherin-mediated cell-cell adhesion as well as in signal transduction, has received increasing attention in recent years due to its role as an oncogene in various human cancers. The primary sequence of the human beta-catenin gene (CTNNB1) has been known for some time, but that of the rat beta-catenin gene (Ctnnb1) has not heretofore been studied in detail. We report here the primary structure of Ctnnb1 using PCR-based methods and direct sequencing. The size of the complete Ctnnb1 gene was determined to be 9082 bp. We found the rat Ctnnb1 gene to contain 14 exons, ranging in size from 61 to 356 bp, and 13 introns ranging in size from 76 to 2524 bp. The transcription start site appears to be 157 bp upstream of the ATG codon located in exon 1. The resulting transcript is 2650 nucleotides long (encoding a protein of 781 amino acids). We found the 5' UTR to consist of 157 nucleotides and the 3' UTR to be 147 nucleotides long. The region coding for the glycogen synthase kinase-3beta domain of beta-catenin is located in exon 2 of rat Ctnnb1, in contrast to human CTNNB1 in which it is found in exon 3. Based on the newly acquired knowledge of the primary sequence, more than a dozen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced rat liver tumors were screened for the presence or absence of mutations in all 14 exons of rat Ctnnb1. Surprisingly, no mutations were found. The results are discussed in the context of the organ-specificity of IQ-induced mutations in beta-catenin, being highly prevalent in colon tumors, but much less common in liver tumors.

Alternate JournalGene
PubMed ID11867232
Grant ListR01 CA080176-03 / CA / NCI NIH HHS / United States
CA80176 / CA / NCI NIH HHS / United States
R01 CA065525-08 / CA / NCI NIH HHS / United States
R01 CA080176-02 / CA / NCI NIH HHS / United States
R01 CA065525-09 / CA / NCI NIH HHS / United States
R01 CA080176-05 / CA / NCI NIH HHS / United States
CA65525 / CA / NCI NIH HHS / United States
R01 CA065525-07 / CA / NCI NIH HHS / United States
R01 CA080176-04 / CA / NCI NIH HHS / United States
R01 CA065525-06A1 / CA / NCI NIH HHS / United States