| Co-Investigator(Kenkyū-buntansha) |
ISHIBASHI Yoshitomo Nippon Medical School, Institute of Gerontology, Assistant Professor, 老人病研究所, 助手 (00312067)
OHTA Shigeo Nippon Medical School, Institute of Gerontology, Professor, 老人病研究所, 教授 (00125832)
|
|---|
| Research Abstract |
The purpose of this project is to reveal the molecular mechanism of crosstalk between the nucleus and the mitochondrion when mitochondrial DNA (mtDNA) is damaged. In this project, we have cloned a novel cDNA which is up-regulated in HeLa cells completely lacking mtDNA by differential display. The gene is named MIDAS (Mitochondrial DNA Damage Sensitive novel factor). MIDAS has 298 amino acid residues and a leucine zipper motif. By homology search, a homolog of MIDAS was found in various species (yeast, nematode, drosophila, and rat), suggesting that the function(s) of MIDAS is evolutionally conserved. Northern blot analysis showed that MIDAS was ubiquitously expressed in various human tissues. We prepared anti-MIDAS serum to perform immunohistochemical staining and Western blot analysis. MIDAS was shown to mainly locate in mitochondria. The expression of MIDAS in HeLa cells was induced by ethidium bromide (EtBr), which is known to inhibit the replication of mtDNA and decrease the amount of mtDNA. A respiratory chain inhibitor, antimycin A could not induce MIDAS. The increased MIDAS facilitated mtDNA recovery from the reduced level to the normal level. We have determined that MIDAS binds to G-rich nucleotide sequences by CASTing experiments. These results suggest that MIDAS is induced in response to the reduction of mtDNA and involved in the replication of mtDNA to increase mtDNA.
|
