title: p53 directly regulates the transcription of the human frataxin gene and its lack of regulation in tumor cells decreases the utilization of mitochondrial iron.
abstract: Mitochondrial frataxin functions in iron homeostasis, biogenesis of iron-sulfur clusters, protection from oxidative stress and apoptosis, and as a tumor suppressor protein. We examined regulation of the expression of the human frataxin by p53. Pifithrin-α, an inhibitor of p53 function, and knockdown of p53 decreased the level of frataxin mRNA in human kidney HEK 293T cells. The transcriptional activity of the human frataxin gene is enhanced by the proximal promoter containing the p53-responsive element (p53RE) on the gene. Chromatin immunoprecipitation assay and electrophoretic mobility shift assay confirmed the binding of p53 to the human frataxin p53RE. The expression of wild-type p53 in human cancer HeLa cells increased the reporter activity carrying p53RE at the region of -209 to -200bp of the frataxin promoter. Finally, when the HeLa cells overexpressing frataxin were treated with 5-aminolevulinic acid (ALA), there was less accumulation of protoporphyrin than HeLa control cells, and it was sharply decreased by the addition of iron citrate, suggesting that the utilization of mitochondrial iron for heme biosynthesis can be dependent on the level of frataxin. Alternatively, the low expression of frataxin not regulated by p53 in tumor cells lowers the utilization of iron in mitochondria, causing the tumor-specific ALA-induced accumulation of protoporphyrin.
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Rina
authors.initials: R
authors.lastname: Shimizu
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Nguyen Ngoc
authors.initials: NN
authors.lastname: Lan
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Tran Tien
authors.initials: TT
authors.lastname: Tai
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Adachi
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Asako
authors.initials: A
authors.lastname: Kawazoe
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Anfeng
authors.initials: A
authors.lastname: Mu
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan; Insect Biomedical Center, Kyoto Institute of Technology, Kyoto 606-8585, Japan. Electronic address: taketani@kit.ac.jp.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Taketani
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology; D001483:Base Sequence; D005290:Ferric Compounds / Q000494:pharmacology; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D016158:Genes, p53; D057809:HEK293 Cells; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D033862:Iron-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011524:Protoporphyrins / Q000378:metabolism; D020218:Response Elements; D000096923:Frataxin
chemical_list: D000622:Aminolevulinic Acid; D005290:Ferric Compounds; D007501:Iron; D033862:Iron-Binding Proteins; D011524:Protoporphyrins; D000096923:Frataxin; C025314:ferric citrate
keywords: ALA; Cancerous cells; Frataxin; Heme biosynthesis; Transcription; p53