The Role of Nrf2 Transcription Factor and Sp1-Nrf2 Protein Complex in Glutamine Transporter SN1 Regulation in Mouse Cortical Astrocytes Exposed to Ammonia

Ammonia toxicity in the brain primarily affects astrocytes via a mechanism in which oxidative stress (OS), is coupled to the imbalance between glutamatergic and GABAergic transmission. Ammonia also downregulates the astrocytic N system transporter SN1 that controls glutamine supply from astrocytes to neurons for the replenishment of both neurotransmitters. Here, we tested the hypothesis that activation of Nrf2 is the process that links ammonia-induced OS formation in astrocytes to downregulation and inactivation of SN1 and that it may involve the formation of a complex between Nrf2 and Sp1. Treatment of cultured cortical mouse astrocytes with ammonia (5 mM NH4Cl for 24 h) evoked Nrf2 nuclear translocation, increased its activity in a p38 MAPK pathway-dependent manner, and enhanced Nrf2 binding to Slc38a3 promoter. Nrf2 silencing increased SN1 mRNA and protein level without influencing astrocytic [3H]glutamine transport. Ammonia decreased SN1 expression in Nrf2 siRNA treated astrocytes and reduced [3H]glutamine uptake. In addition, while Nrf2 formed a complex with Sp1 in ammonia-treated astrocytes less efficiently than in control cells, treatment of astrocytes with hybrid-mode inactivated Sp1-Nrf2 complex (Nrf2 silencing + pharmacological inhibition of Sp1) did not affect SN1 protein level in ammonia-treated astrocytes. In summary, the results document that SN1 transporter dysregulation by ammonia in astrocytes involves activation of Nrf2 but does not require the formation of the Sp1-Nrf2 complex.

[1]  F. Chaudhry,et al.  Perturbation of astroglial Slc38 glutamine transporters by NH4 + contributes to neurophysiologic manifestations in acute liver failure , 2021, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[2]  K. Furuta,et al.  Oxindole-curcumin hybrid compound enhances the transcription of γ-glutamylcysteine ligase. , 2021, European journal of pharmacology.

[3]  D. Häussinger,et al.  O-GlcNAcylation-dependent upregulation of HO1 triggers ammonia-induced oxidative stress and senescence in hepatic encephalopathy. , 2019, Journal of hepatology.

[4]  M. Zielińska,et al.  Silencing of Transcription Factor Sp1 Promotes SN1 Transporter Regulation by Ammonia in Mouse Cortical Astrocytes , 2019, International journal of molecular sciences.

[5]  M. Zielińska,et al.  Persistent Overexposure to N-Methyl-d-Aspartate (NMDA) Calcium-Dependently Downregulates Glutamine Synthetase, Aquaporin 4, and Kir4.1 Channel in Mouse Cortical Astrocytes , 2018, Neurotoxicity Research.

[6]  M. Zielińska,et al.  Protein kinase C-mediated impairment of glutamine outward transport and SN1 transporter distribution by ammonia in mouse cortical astrocytes , 2018, Neurochemistry International.

[7]  D. Häussinger,et al.  Hepatic Encephalopathy and Astrocyte Senescence. , 2018, Journal of clinical and experimental hepatology.

[8]  H. Daniel,et al.  NRF2 regulates the glutamine transporter Slc38a3 (SNAT3) in kidney in response to metabolic acidosis , 2018, Scientific Reports.

[9]  M. Nedergaard,et al.  Physiology of Astroglia. , 2018, Physiological reviews.

[10]  Chih‐Chung Lin,et al.  Arachidonic Acid Induces ARE/Nrf2-Dependent Heme Oxygenase-1 Transcription in Rat Brain Astrocytes , 2018, Molecular Neurobiology.

[11]  U. Sonnewald,et al.  System N transporters are critical for glutamine release and modulate metabolic fluxes of glucose and acetate in cultured cortical astrocytes: changes induced by ammonia , 2016, Journal of neurochemistry.

[12]  S. Ciordia,et al.  Ammonia Affects Astroglial Proliferation in Culture , 2015, PloS one.

[13]  R. Butterworth.  Pathophysiology of brain dysfunction in hyperammonemic syndromes: The many faces of glutamine. , 2014, Molecular genetics and metabolism.

[14]  Chih‐Chung Lin,et al.  CO Induces Nrf2-Dependent Heme Oxygenase-1 Transcription by Cooperating with Sp1 and c-Jun in Rat Brain Astrocytes , 2014, Molecular Neurobiology.

[15]  S. Welford,et al.  Expression of Glutamine Transporter Slc38a3 (SNAT3) During Acidosis is Mediated by a Different Mechanism than Tissue-Specific Expression , 2014, Cellular Physiology and Biochemistry.

[16]  Baoman Li,et al.  Ammonia-induced Na,K-ATPase/ouabain-mediated EGF receptor transactivation, MAPK/ERK and PI3K/AKT signaling and ROS formation cause astrocyte swelling , 2013, Neurochemistry International.

[17]  A. Schousboe,et al.  Astrocytic Control of Biosynthesis and Turnover of the Neurotransmitters Glutamate and GABA , 2013, Front. Endocrinol..

[18]  H. Aburatani,et al.  Nrf2 redirects glucose and glutamine into anabolic pathways in metabolic reprogramming. , 2012, Cancer cell.

[19]  M. Aschner,et al.  15-Deoxy-Δ12,14-prostaglandin J₂ modulates manganese-induced activation of the NF-κB, Nrf2, and PI3K pathways in astrocytes. , 2012, Free radical biology & medicine.

[20]  J. Y. Lee,et al.  Nrf2 and Sp family synergistically enhance the expression of ion transporters in potassium-depleted conditions. , 2012, Journal of nephrology.

[21]  M. Aschner,et al.  Disruption of astrocytic glutamine turnover by manganese is mediated by the protein kinase C pathway , 2011, Glia.

[22]  M. Aschner,et al.  Manganese‐induced downregulation of astroglial glutamine transporter SNAT3 involves ubiquitin‐mediated proteolytic system , 2010, Glia.

[23]  M. Aschner,et al.  Roles of glutamine in neurotransmission. , 2010, Neuron glia biology.

[24]  M. Norenberg,et al.  Glutamine as a mediator of ammonia neurotoxicity: A critical appraisal. , 2010, Biochemical pharmacology.

[25]  J. Albrecht,et al.  Direct exposure to ammonia and hyperammonemia increase the extracellular accumulation and degradation of astroglia-derived glutathione in the rat prefrontal cortex. , 2010, Toxicological sciences : an official journal of the Society of Toxicology.

[26]  P. Desjardins,et al.  Evidence for oxidative/nitrosative stress in the pathogenesis of hepatic encephalopathy , 2010, Metabolic Brain Disease.

[27]  D. Häussinger,et al.  Interaction of oxidative stress, astrocyte swelling and cerebral ammonia toxicity , 2010, Current opinion in clinical nutrition and metabolic care.

[28]  N. Kitteringham,et al.  The keap1-nrf2 cellular defense pathway: mechanisms of regulation and role in protection against drug-induced toxicity. , 2010, Handbook of experimental pharmacology.

[29]  G. Bodega,et al.  Effect of ammonia, glutamine, and serum on calcineurin, p38MAPK-diP, GADD153/CHOP10, and CNTF in primary rat astrocyte cultures , 2007, Brain Research.

[30]  J. Albrecht,et al.  Upregulation of cerebral cortical glutathione synthesis by ammonia in vivo and in cultured glial cells: The role of cystine uptake , 2007, Neurochemistry International.

[31]  A. Schousboe,et al.  Glutamine in the central nervous system: function and dysfunction. , 2007, Frontiers in bioscience : a journal and virtual library.

[32]  M. Norenberg,et al.  Oxidative Stress and Mitogen-Activated Protein Kinase Phosphorylation Mediate Ammonia-Induced Cell Swelling and Glutamate Uptake Inhibition in Cultured Astrocytes , 2006, The Journal of Neuroscience.

[33]  Masayuki Yamamoto,et al.  Nrf2-Keap1 regulation of cellular defense mechanisms against electrophiles and reactive oxygen species. , 2006, Advances in enzyme regulation.

[34]  DelindaA . Johnson,et al.  Nuclear Factor E2-Related Factor 2-Dependent Antioxidant Response Element Activation by tert-Butylhydroquinone and Sulforaphane Occurring Preferentially in Astrocytes Conditions Neurons against Oxidative Insult , 2004, The Journal of Neuroscience.

[35]  T. Murphy,et al.  Coordinate Regulation of Glutathione Biosynthesis and Release by Nrf2-Expressing Glia Potently Protects Neurons from Oxidative Stress , 2003, The Journal of Neuroscience.

[36]  F. Schliess,et al.  Ammonia‐induced heme oxygenase‐1 expression in cultured rat astrocytes and rat brain in vivo , 2002, Glia.

[37]  J. Matés,et al.  Glutamine and its relationship with intracellular redox status, oxidative stress and cell proliferation/death. , 2002, The international journal of biochemistry & cell biology.

[38]  K. Zilles,et al.  Ammonia induces MK‐801‐sensitive nitration and phosphorylation of protein tyrosine residues in rat astrocytes , 2002, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[39]  M. Norenberg,et al.  Elevation of glutathione levels by ammonium ions in primary cultures of rat astrocytes , 2000, Neurochemistry International.

[40]  D. Copenhagen,et al.  Molecular Analysis of System N Suggests Novel Physiological Roles in Nitrogen Metabolism and Synaptic Transmission , 1999, Cell.