Characterization of the 3' untranslated region of mouse DNA topoisomerase IIalpha mRNA.
Expression of DNA topoisomerase IIalpha protein varies through the cell cycle with its peak in G2/M. This cell-cycle-dependent expression depends on changes in topoisomerase IIalpha mRNA stability as well as promoter activity. We isolated the 3' genomic region of the mouse topoisomerase IIalpha gene and investigated whether or not the 3' untranslated region (UTR) of the topoisomerase IIalpha mRNA participates in the cell-cycle-dependent mRNA stability. Interestingly, genomic- and RT-PCR analyses revealed that the topoisomerase IIalpha 3' UTR is formed via splicing in mouse, but not in human and hamster. Comparison of the mouse 3' region with the human and hamster regions suggests that this mouse-specific splicing has resulted from an accidental acquisition of the consensus 5' splice site. The minority of the non-spliced topoisomerase IIalpha 3' UTR in mouse was confirmed by Northern blot analysis. We performed transient expression assays using luciferase constructs with the mouse topoisomerase IIalpha 3' genomic region, or the major spliced form of the 3' UTR. However, neither construct affected the cell-cycle-dependent expression of the reporter gene driven by the topoisomerase IIalpha promoter. Our results strongly suggest that the mouse topoisomerase IIalpha 3' UTR by itself is not involved in the cell-cycle-dependent mRNA stability.
Kobayashi
M
M
Kihara Institute for Biological Research, Yokohama City University, Maioka-cho 641-12, Totsuka-ku, Yokohama 244, Japan.
Adachi
N
N
Koyama
H
H
D016475:3T3 Cells; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000951:Antigens, Neoplasm; D001483:Base Sequence; D016466:CHO Cells; D003001:Cloning, Molecular; D017124:Conserved Sequence; D006224:Cricetinae; D003412:Cricetulus; D004250:DNA Topoisomerases, Type II / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D004268:DNA-Binding Proteins; D015971:Gene Expression Regulation, Enzymologic; D014644:Genetic Variation; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D004250:DNA Topoisomerases, Type II