title: Nuclear respiratory factor 2 regulates the expression of the same NMDA receptor subunit genes as NRF-1: both factors act by a concurrent and parallel mechanism to couple energy metabolism and synaptic transmission.
abstract: Neuronal activity and energy metabolism are tightly coupled processes. Previously, we found that nuclear respiratory factor 1 (NRF-1) transcriptionally co-regulates energy metabolism and neuronal activity by regulating all 13 subunits of the critical energy generating enzyme, cytochrome c oxidase (COX), as well as N-methyl-d-aspartate (NMDA) receptor subunits 1 and 2B, GluN1 (Grin1) and GluN2B (Grin2b). We also found that another transcription factor, nuclear respiratory factor 2 (NRF-2 or GA-binding protein) regulates all subunits of COX as well. The goal of the present study was to test our hypothesis that NRF-2 also regulates specific subunits of NMDA receptors, and that it functions with NRF-1 via one of three mechanisms: complementary, concurrent and parallel, or a combination of complementary and concurrent/parallel. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation of mouse neuroblastoma cells and rat visual cortical tissue, promoter mutations, real-time quantitative PCR, and western blot analysis, NRF-2 was found to functionally regulate Grin1 and Grin2b genes, but not any other NMDA subunit genes. Grin1 and Grin2b transcripts were up-regulated by depolarizing KCl, but silencing of NRF-2 prevented this up-regulation. On the other hand, over-expression of NRF-2 rescued the down-regulation of these subunits by the impulse blocker TTX. NRF-2 binding sites on Grin1 and Grin2b are conserved among species. Our data indicate that NRF-2 and NRF-1 operate in a concurrent and parallel manner in mediating the tight coupling between energy metabolism and neuronal activity at the molecular level.
authors.affiliation: Department of Cell Biology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Anusha
authors.initials: A
authors.lastname: Priya
authors.forename: Kaid
authors.initials: K
authors.lastname: Johar
authors.forename: Margaret T T
authors.initials: MT
authors.lastname: Wong-Riley
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004734:Energy Metabolism / Q000235:genetics* / Q000502:physiology; D051268:GA-Binding Protein Transcription Factor / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D051266:Nuclear Respiratory Factor 1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D009435:Synaptic Transmission / Q000235:genetics* / Q000502:physiology
chemical_list: D051268:GA-Binding Protein Transcription Factor; D051266:Nuclear Respiratory Factor 1; D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate