| Project/Area Number |
60480499
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
代謝生物化学
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| Research Institution | Osaka University |
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Principal Investigator |
TANAKA Takehiko Osaka University Medical School, 医学部, 教授 (60028272)
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| Co-Investigator(Kenkyū-buntansha) |
NOGUCHI Tamio Osaka University Medical School, 医学部, 助手 (70135721)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1986: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1985: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Keywords | Insulin / Fructose-L-type pyruvate kinase / Regulation of gene expression / 遺伝子発現の調節 / ピルビン酸キナーゼL遺伝子 |
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| Research Abstract |
Regulation of the expression of the hepatic L-type pyruvate kinase gene by insulin and fructose was studied in diabetic rats. Insulin stimulated transcription of the pyruvate kinase L gene. Cycloheximide inhibited the induction caused by insulin, suggesting that insulin may stimulate transcription of the pyruvate kinase L gene by stimulating synthesis of some unknown protein. On the other hand, feeding fructose had no effect on transcription of the pyruvate kinase L gene. Since increases in the levels of putative nuclear RNA precursor species of the pyruvate kinase L after fructose feeding preceded changes in the levels of cytosolic pyruvate kinase L mRNA, fructose may increase the levels of pyruvate kinase L mRNA by stabilizing nuclear RNA species. The effect of fructose on pyruvate kinase L was not mediated by hormones such as glucagon, glucocorticoid and thyroid hormones, and thus seems to be directly on the liver.
Comparison of the nucleotide sequence of rat R-type isozyme mRNA with that of the L-type isozyme showed that the R-type isozyme mRNA had an identical nucleotide sequence to that of the L-type except in the 5' terminal region including the coding sequence: the sequence upstream of the 5th coding residue of the L-type was replaced by a 98-nucleotide coding sequence plus a 5' untranslated region in the R-type isozyme. By sequence analysis of a genomic clone of LPK30 twelve exons were identified, of which the first and second exons coded the R- and L-specific sequences, respectively. The remaining exons present downstream coded amino acids common to the two isozymes. Thus, we suggest that the two isozyme mRNAs are generated by use of different promoters.
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