1997 Fiscal Year Final Research Report Summary
Assessment of individual functions of Myc family genes
| Project/Area Number |
08044286
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
Molecular biology
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| Research Institution | Osaka University |
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Principal Investigator |
KONDOH Hisato Osaka Univ., IMCB,Professor, 細胞生体工学センター, 教授 (70127083)
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| Co-Investigator(Kenkyū-buntansha) |
ANDRAS Nagy Mount Sinai Hospital Research Institute, Senior Scientist, Research Institute, Senior Sci
KAMACHI Yusuke Osaka Unlv., IMCB,Research Associate, 細胞生体工学センター, 助手 (90263334)
HIGASHI Yujiro Osaka Unlv., IMCB,Associate Professor, 細胞生体工学センター, 助教授 (30181069)
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| Project Period (FY) |
1996 – 1997
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| Keywords | N-myc / L-myc / C-myc / KO mouse / transcription / embryo |
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| Research Abstract |
To check the possibility of functional redundancy between the N-myc and L-myc genes, we generated N^<+/->L^<-/-> as well as N-myc and L-myc double mutant mice (N^<-/->L^<-/->). N-myc and L-myc double mutant embryos showed an overall phenotype similar to ablating N-myc only in mice (N^<-/->L^<+/+> or N^<-/->L^<+/>). The results indicate that L-myc is not essential for embryonic development, and negates the notion of redundant functions between the N-myc and L-myc genes.
To identify N-myc regulatory target genes we subtracted total cDNAs of mutant embryo from wild type cDNAs at 10.5 dpc and vice versa, and isolated cDNA of down-regulated mRNA in the mutants or of up-regulated mRNA species in the opposite combination. One of the N-myc downstream genes, Ndrl was studied in detail. The promoter of Ndrl gene was directly repressed by N-myc and Max heterodimer complex. In various embryonic organ rudiments an inverse relationship was found between the expression of N-myc and Ndrl, indicating that repression of the latter by the former is a regulation operating in embryogenesis.
To address whether N-myc and c-myc have overlapping functions, we have introduced the c-myc coding region into the N-myc locus so that it comes under the regulation of N-myc. No heterozygous offspring were observed among 32 ES cell "fathered" pups. This is a strong indication that the embryos expressing c-myc from the N-myc locus die in utero or may not even be generated.
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