title: CHOP (C/EBP homologous protein) and ASNS (asparagine synthetase) induction in cybrid cells harboring MELAS and NARP mitochondrial DNA mutations.
abstract: Mitochondrial dysfunction caused by mutations in mitochondrial DNA (mtDNA) is related to a variety of diseases including MELAS and NARP syndromes. However, little is known about the intracellular responses induced by mtDNA mutations. In order to identify genes whose expression is altered as a result of the presence of mtDNA mutations, DNA microarray analysis was performed using human 143B osteosarcoma cells harboring 3243A>G [tRNA-Leu (UUR)] and 8993T>G [ATPase6 Leu156Arg] mtDNA mutations associated with MELAS and NARP syndromes (2SD and NARP3-1 cybrid cells), respectively. We found that mRNA and protein levels of ATF4, CHOP and ASNS were upregulated in 2SD and NARP3-1 cells as compared with parental cells. Reporter assays demonstrated that transcription of CHOP and ASNS genes was upregulated through the AARE (amino acid regulatory element) and NSRE-1 (nutrient-sensing response element-1) enhancer elements to which ATF4 binds, respectively. Furthermore, knockdown of ATF4 by RNA interference reduced CHOP and ASNS transcription in 2SD and NARP3-1 cells. These results suggest that the presence of mtDNA mutations elicits upregulation of CHOP and ASNS genes through the elevation of ATF4 expression and its binding to the AARE and NSRE-1, respectively.
authors.affiliation: Department of Longevity and Aging Research, Gifu International Institute of Biotechnology, 1-1 Naka-Fudogaoka, Kakamigahara, Gifu 504-0838, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Fujita
authors.forename: Masafumi
authors.initials: M
authors.lastname: Ito
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nozawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoneda
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Oshida
authors.forename: Masashi
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D051701:Activating Transcription Factor 4 / Q000235:genetics; D000975:Antioxidants / Q000494:pharmacology; D001217:Aspartate-Ammonia Ligase / Q000096:biosynthesis* / Q000235:genetics; D001259:Ataxia / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D006801:Humans; D006822:Hybrid Cells; D017241:MELAS Syndrome / Q000235:genetics*; D028361:Mitochondrial Diseases / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D012516:Osteosarcoma / Q000378:metabolism; D010523:Peripheral Nervous System Diseases / Q000235:genetics*; D034622:RNA Interference; D012174:Retinitis Pigmentosa / Q000235:genetics*; D012402:Rotenone / Q000494:pharmacology; D013577:Syndrome; D051742:Transcription Factor CHOP / Q000096:biosynthesis* / Q000235:genetics; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C497109:ATF4 protein, human; D000975:Antioxidants; C497249:DDIT3 protein, human; D004272:DNA, Mitochondrial; D012402:Rotenone; D051701:Activating Transcription Factor 4; D051742:Transcription Factor CHOP; D001217:Aspartate-Ammonia Ligase