title: Regulation of Na(+)/K(+)-ATPase by nuclear respiratory factor 1: implication in the tight coupling of neuronal activity, energy generation, and energy consumption.
abstract: BACKGROUND
  NRF-1 regulates mediators of neuronal activity and energy generation.
  
  
  RESULTS
  NRF-1 transcriptionally regulates Na(+)/K(+)-ATPase subunits α1 and β1.
  
  
  CONCLUSIONS
  NRF-1 functionally regulates mediators of energy consumption in neurons.
  
  
  CONCLUSIONS
  NRF-1 mediates the tight coupling of neuronal activity, energy generation, and energy consumption at the molecular level. Energy generation and energy consumption are tightly coupled to neuronal activity at the cellular level. Na(+)/K(+)-ATPase, a major energy-consuming enzyme, is well expressed in neurons rich in cytochrome c oxidase, an important enzyme of the energy-generating machinery, and glutamatergic receptors that are mediators of neuronal activity. The present study sought to test our hypothesis that the coupling extends to the molecular level, whereby Na(+)/K(+)-ATPase subunits are regulated by the same transcription factor, nuclear respiratory factor 1 (NRF-1), found recently by our laboratory to regulate all cytochrome c oxidase subunit genes and some NMDA and AMPA receptor subunit genes. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation, promoter mutational analysis, and real-time quantitative PCR, NRF-1 was found to functionally bind to the promoters of Atp1a1 and Atp1b1 genes but not of the Atp1a3 gene in neurons. The transcripts of Atp1a1 and Atp1b1 subunit genes were up-regulated by KCl and down-regulated by tetrodotoxin. Atp1b1 is positively regulated by NRF-1, and silencing of NRF-1 with small interference RNA blocked the up-regulation of Atp1b1 induced by KCl, whereas overexpression of NRF-1 rescued these transcripts from being suppressed by tetrodotoxin. On the other hand, Atp1a1 is negatively regulated by NRF-1. The binding sites of NRF-1 on Atp1a1 and Atp1b1 are conserved among mice, rats, and humans. Thus, NRF-1 regulates key Na(+)/K(+)-ATPase subunits and plays an important role in mediating the tight coupling between energy consumption, energy generation, and neuronal activity at the molecular level.
authors.affiliation: Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Kaid
authors.initials: K
authors.lastname: Johar
authors.forename: Anusha
authors.initials: A
authors.lastname: Priya
authors.forename: Margaret T T
authors.initials: MT
authors.lastname: Wong-Riley
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D004734:Energy Metabolism; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000201:enzymology* / Q000378:metabolism; D051266:Nuclear Respiratory Factor 1 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: C503552:Atp1b1 protein, mouse; D051266:Nuclear Respiratory Factor 1; C497344:Atp1a1 protein, mouse; D000254:Sodium-Potassium-Exchanging ATPase