Expression of rainbow trout apolipoprotein A-I genes in liver and hepatocellular carcinoma.
Screening for genes overexpressed in trout aflatoxin B1-induced hepatocellular carcinomas resulted in the isolation of cDNA sequences of two apolipoprotein A-Is, apoA-I-1 and apoA-I-2. The levels of apoA-I-1 and -2 mRNAs of liver and tumor were quite different. ApoA-I-1 mRNA was the major species in liver, while apoA-I-1 and -2 mRNAs were present at similar levels in several tumors. This elevated level of apoA-I-2 mRNA was observed in seven different tumors, suggesting that the overexpression of apoA-I-2 was a general feature of aflatoxin B1-induced liver tumors. Hybridization to genomic DNA demonstrated that trout has two different apoA-I genes which is in contrast to other vertebrates which have one gene coding for apoA-I. Liver apoA-I-1 and -2 cDNA clones specified the same amino acid sequence as the tumor apoA-I-1 and -2 cDNA clones. Analysis of the cDNA-derived amino acid sequences showed that trout apoA-I-1 and -2, like human apoA-I, consist largely of multiple 22 amino acid repeats having the potential to generate an amphipathic alpha-helix. The similarity of the repeat pattern in trout and human apoA-Is suggests that all the internal repeats in these sequences arose before the fish-mammal split, some 400 million years ago.
Delcuve
G P
GP
Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Sun
J M
JM
Davie
J R
JR
D016604:Aflatoxin B1; D000595:Amino Acid Sequence; D000818:Animals; D016632:Apolipoprotein A-I / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015139:Blotting, Southern; D004273:DNA, Neoplasm; D004591:Electrophoresis, Polyacrylamide Gel; D015972:Gene Expression Regulation, Neoplastic; D016678:Genome; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012474:Salmon; D016415:Sequence Alignment; D014158:Transcription, Genetic
D016632:Apolipoprotein A-I; D004273:DNA, Neoplasm; D016604:Aflatoxin B1