Nuclear respiratory factor 2 senses changing cellular energy demands and its silencing down-regulates cytochrome oxidase and other target gene mRNAs.
Cytochrome c oxidase (COX), the terminal enzyme of the electron transport chain, is a bigenomic enzyme with 13 subunits. The mechanism coordinating the transcription of these subunits is poorly understood. We investigated the role of nuclear respiratory factor-2 (NRF-2) in intragenomic regulation of nuclear COX genes. Vector-mediated short-hairpin RNA interference against NRF-2alpha reduced all 10 COX nuclear subunit mRNAs and mRNAs of other genes involved in mitochondrial function/biogenesis. NRF-2 binding site was necessary for the rat COX 4i1 promoter to down-regulate in response to decreased energy demands in primary neurons. Over-expression of NRF-2 protein prevented the down-regulation of transcriptional activity by TTX. Finally, NRF-2 binding sites in isolation were sufficient for modulating COX subunit 4i1 and 6A1 promoters' activity in response to decreased energy demand. These results indicate that NRF-2 is a vital part of a molecular mechanism that senses upstream energy signals and modulates COX transcriptional levels in mammalian cells.
Ongwijitwat
Sakkapol
S
Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, United States.
Liang
Huan Ling
HL
Graboyes
Evan M
EM
Wong-Riley
Margaret T T
MT
D000818:Animals; D000831:Animals, Newborn; D001665:Binding Sites; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D015536:Down-Regulation; D003576:Electron Transport Complex IV / Q000235:genetics*; D004734:Energy Metabolism; D015971:Gene Expression Regulation, Enzymologic; D020868:Gene Silencing; D005822:Genetic Vectors; D051379:Mice; D041681:NIH 3T3 Cells; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051264:Nuclear Respiratory Factors / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D013779:Tetrodotoxin / Q000633:toxicity; D014158:Transcription, Genetic
D051264:Nuclear Respiratory Factors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013779:Tetrodotoxin; D003576:Electron Transport Complex IV