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• W2969790734 abstract "The angiogenin (ANG) gene is mutated frequently in individuals with amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. Delivering human ANG to mice that display ALS-like symptoms extends their lifespan and improves motor function. ANG is a secretory vertebrate RNase that enters neuronal cells and cleaves a subset of tRNAs, leading to the inhibition of translation initiation and the assembly of stress granules. Here, using murine neuronal and astrocytic cell lines, we find that ANG triggers the activation of the Nrf2 (nuclear factor erythroid 2-related factor 2) pathway, which provides a critical cellular defense against oxidative stress. This activation, which occurred in astrocytes but not in neurons, promoted the survival of proximal neurons that had oxidative injury. These findings extend the role of ANG as a neuroprotective agent and underscore its potential utility in ALS management. The angiogenin (ANG) gene is mutated frequently in individuals with amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. Delivering human ANG to mice that display ALS-like symptoms extends their lifespan and improves motor function. ANG is a secretory vertebrate RNase that enters neuronal cells and cleaves a subset of tRNAs, leading to the inhibition of translation initiation and the assembly of stress granules. Here, using murine neuronal and astrocytic cell lines, we find that ANG triggers the activation of the Nrf2 (nuclear factor erythroid 2-related factor 2) pathway, which provides a critical cellular defense against oxidative stress. This activation, which occurred in astrocytes but not in neurons, promoted the survival of proximal neurons that had oxidative injury. These findings extend the role of ANG as a neuroprotective agent and underscore its potential utility in ALS management. Amyotrophic lateral sclerosis (ALS) 4The abbreviations used are: ALSamyotrophic lateral sclerosishPAPhuman placental alkaline phosphataseROSreactive oxygen speciestBHQtert-butylhydroquinonetiRNAtRNA-derived, stress-induced RNAqPCRquantitative PCRptRNasepancreatic-type RNaseAREantioxidant-response elementCEMEMcomplete mediumNBMneurobasal medium. is a progressive, late-onset, and fatal neurodegenerative disease that is characterized by selective motor neuron loss in the spinal cord, brainstem, and motor cortex (1Taylor J.P. Brown Jr., R.H. Cleveland D.W. Decoding ALS: from genes to mechanism.Nature. 2016; 539 (27830784): 197-20610.1038/nature20413Crossref PubMed Scopus (1093) Google Scholar). Approximately 10% of ALS cases are inherited dominantly. The most common genetic determinants of ALS are the expansion of noncoding GGGGCC repeats in C9ORF72 and mutations in the copper/zinc superoxide dismutase 1 (SOD1) locus (2Zhang K. Donnelly C.J. Haeusler A.R. Grima J.C. Machamer J.B. Steinwald P. Daley E.L. Miller S.J. Cunningham K.M. Vidensky S. Gupta S. Thomas M.A. Hong I. Chiu S.-L. Huganir R.L. et al.The C9orf72 repeat expansion disrupts nucleocytoplasmic transport.Nature. 2015; 525 (26308891): 56-6110.1038/nature14973Crossref PubMed Scopus (638) Google Scholar, 3Kaur S.J. McKeown S.R. Rashid S. Mutant SOD1 mediated pathogenesis of amyotrophic lateral sclerosis.Gene. 2016; 577 (26657039): 109-11810.1016/j.gene.2015.11.049Crossref PubMed Scopus (177) Google Scholar). The search for other gene mutations that segregate with disease in ALS pedigrees has led to loss-of-function mutations in the human angiogenin (ANG) gene (4Greenway M.J. Andersen P.M. Russ C. Ennis S. Cashman S. Donaghy C. Patterson V. Swingler R. Kieran D. Prehn J. Morrison K.E. Green A. Acharya K.R. Brown Jr., R.H. Hardiman O. ANG mutations segregate with familial and “sporadic” amyotrophic lateral sclerosis.Nat. Genet. 2006; 38 (16501576): 411-41310.1038/ng1742Crossref PubMed Scopus (572) Google Scholar, 5Wu D. Yu W. Kishikawa H. Folkerth R.D. Iafrate A.J. Shen Y. Xin W. Sims K. Hu G.-F. Angiogenin loss-of-function mutations in amyotrophic lateral sclerosis.Ann. Neurol. 2007; 62 (17886298): 609-61710.1002/ana.21221Crossref PubMed Scopus (158) Google Scholar6Gellera C. Colombrita C. Ticozzi N. Castellotti B. Bragato C. Ratti A. Taroni F. Silani V. Identification of new ANG gene mutations in a large cohort of Italian patients with amyotrophic lateral sclerosis.Neurogenetics. 2008; 9 (18087731): 33-4010.1007/s10048-007-0111-3Crossref PubMed Scopus (101) Google Scholar). Indeed, providing ALS-like transgenic mice that overexpress human SOD1G93A with human ANG increases their lifespan and improves their motor function (7Kieran D. Sebastia J. Greenway M.J. King M.A. Connaughton D. Concannon C.G. Fenner B. Hardiman O. Prehn J.H. Control of motoneuron survival by angiogenin.J. Neurosci. 2008; 28 (19109488): 14056-1406110.1523/JNEUROSCI.3399-08.2008Crossref PubMed Scopus (136) Google Scholar). amyotrophic lateral sclerosis human placental alkaline phosphatase reactive oxygen species tert-butylhydroquinone tRNA-derived, stress-induced RNA quantitative PCR pancreatic-type RNase antioxidant-response element complete medium neurobasal medium. ANG belongs to the pancreatic-type RNase (ptRNase) superfamily (8Strydom D.J. Fett J.W. Lobb R.R. Alderman E.M. Bethune J.L. Riordan J.F. Vallee B.L. Amino acid sequence of human tumor derived angiogenin.Biochemistry. 1985; 24 (2866794): 5486-549410.1021/bi00341a031Crossref PubMed Scopus (307) Google Scholar). This secretory protein is able to enter cells and catalyze the cleavage of the anticodon loops of mature tRNAs to produce 5′ and 3′ fragments that are designated as tRNA-derived, stress-induced RNAs (tiRNAs) (9Lyons S.M. Fay M.M. Akiyama Y. Anderson P.J. Ivanov P. RNA biology of angiogenin: current state and perspectives.RNA Biol. 2017; 14 (28010172): 171-17810.1080/15476286.2016.1272746Crossref PubMed Scopus (74) Google Scholar). 5′-tiRNAs recruit the translational silencer protein YB-1 and sequester the eukaryotic translation initiation factor 4G/A complex to inhibit translation. Specific 5′-tiRNAs also trigger the assembly of stress granules at sites of ANG localization (10Yamasaki S. Ivanov P. Hu G.-F. Anderson P. Angiogenin cleaves tRNA and promotes stress-induced translational repression.J. Cell Biol. 2009; 185 (19332886): 35-4210.1083/jcb.200811106Crossref PubMed Scopus (599) Google Scholar, 11Ivanov P. Emara M.M. Villen J. Gygi S.P. Anderson P. Angiogenin-induced tRNA fragments inhibit translation initiation.Mol. Cell. 2011; 43 (21855800): 613-62310.1016/j.molcel.2011.06.022Abstract Full Text Full Text PDF PubMed Scopus (611) Google Scholar12Ivanov P. O'Day E. Emara M.M. Wagner G. Lieberman J. Anderson P. G-quadruplex structures contribute to the neuroprotective effects of angiogenin-induced tRNA fragments.Proc. Natl. Acad. Sci. U.S.A. 2014; 111 (25404306): 18201-1820610.1073/pnas.1407361111Crossref PubMed Scopus (207) Google Scholar). Translation repression is critical to overcoming oxidative stress, which is a hallmark of neurological disorders (13Kim G.H. Kim J.E. Rhie S.J. Yoon S. The role of oxidative stress in neurodegenerative diseases.Exp. Neurobiol. 2015; 24 (26713080): 325-34010.5607/en.2015.24.4.325Crossref PubMed Scopus (819) Google Scholar, 14Peters O.M. Ghasemi M. Brown Jr., R.H. Emerging mechanisms of molecular pathology in ALS.J. Clin. Invest. 2015; 125 (25932674): 1767-177910.1172/JCI71601Crossref PubMed Scopus (178) Google Scholar). Oxidative stress results from an imbalance in the production and detoxification of free radicals from reactive oxygen species (ROS) (15D'Amico E. Factor-Litvak P. Santella R.M. Mitsumoto H. Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis.Free Radic. Biol. Med. 2013; 65 (23797033): 509-52710.1016/j.freeradbiomed.2013.06.029Crossref PubMed Scopus (228) Google Scholar, 16Valko M. Leibfritz D. Moncol J. Cronin M.T. Mazur M. Telser J. Free radicals and antioxidants in normal physiological functions and human disease.Int. J. Biochem. Cell Biol. 2007; 39 (16978905): 44-8410.1016/j.biocel.2006.07.001Crossref PubMed Scopus (9970) Google Scholar17Lei X.G. Zhu J.-H. Cheng W.-H. Bao Y. Ho Y.-S. Reddi A.R. Holmgren A. Arnér E.S. Paradoxical roles of antioxidant enzymes: basic mechanisms and health implications.Physiol. Rev. 2016; 96 (26681794): 307-36410.1152/physrev.00010.2014Crossref PubMed Scopus (225) Google Scholar). To neutralize ROS toxicity, cells replenish antioxidants by activating Nrf2 (nuclear factor erythroid 2-related factor 2) (18Johnson D.A. Johnson J.A. Nrf2: a therapeutic target for the treatment of neurodegenerative diseases.Free Radic. Biol. Med. 2015; 88 (26281945): 253-26710.1016/j.freeradbiomed.2015.07.147Crossref PubMed Scopus (219) Google Scholar, 19Kanninen K.M. Pomeshchik Y. Leinonen H. Malm T. Koistinaho J. Levonen A.L. Applications of the Keap1–Nrf2 system for gene and cell therapy.Free Radic. Biol. Med. 2015; 88 (26164630): 350-36110.1016/j.freeradbiomed.2015.06.037Crossref PubMed Scopus (36) Google Scholar). This transcription factor is usually latent within cells. Under basal conditions, the dimeric multidomain protein Keap1 (Kelch-like ECH-associated protein 1) binds to Nrf2 and promotes its ubiquitination and proteasomal degradation by acting as an adaptor for the Cul3-based E3 ligase. Oxidants react with key sulfhydryl groups of Keap1, which then loses its ability to target Nrf2 for degradation. Consequently, Nrf2 enters the nucleus, where it forms a heterodimer with small Maf proteins. This heterodimer binds to antioxidant-response elements (AREs) to drive the expression of antioxidant enzymes that compensate for the physiological and pathophysiological outcomes of oxidant exposure (20Li J. Calkins M.J. Johnson D.A. Johnson J.A. Role of Nrf2-dependent ARE-driven antioxidant pathway in neuroprotection.Methods Mol. Biol. 2007; 399 (18309926): 67-7810.1007/978-1-59745-504-6_6Crossref PubMed Scopus (42) Google Scholar, 21Johnson J.A. Johnson D.A. Kraft A.D. Calkins M.J. Jakel R.J. Vargas M.R. Chen P.C. The Nrf2–ARE pathway: an indicator and modulator of oxidative stress in neurodegeneration.Ann. N.Y. Acad. Sci. 2008; 1147 (19076431): 61-6910.1196/annals.1427.036Crossref PubMed Scopus (469) Google Scholar22Calkins M.J. Johnson D.A. Townsend J.A. Vargas M.R. Dowell J.A. Williamson T.P. Kraft A.D. Lee J.M. Li J. Johnson J.A. The Nrf2/ARE pathway as a potential therapeutic target in neurodegenerative disease.Antioxid. Redox. Signal. 2009; 11 (18717629): 497-50810.1089/ars.2008.2242Crossref PubMed Scopus (353) Google Scholar). Crossing mice in which the Nrf2 gene is overexpressed selectively in astrocytes with two ALS mouse models leads to double transgenic mice with a significant delay in onset and extended survival compared with the single transgenic ALS mice (23Kraft A.D. Resch J.M. Johnson D.A. Johnson J.A. Activation of the Nrf2–ARE pathway in muscle and spinal cord during ALS-like pathology in mice expressing mutant SOD1.Exp. Neurol. 2007; 207 (17631292): 107-11710.1016/j.expneurol.2007.05.026Crossref PubMed Scopus (58) Google Scholar, 24Vargas M.R. Johnson D.A. Sirkis D.W. Messing A. Johnson J.A. Nrf2 activation in astrocytes protects against neurodegeneration in mouse models of familial amyotrophic lateral sclerosis.J. Neurosci. 2008; 28 (19074031): 13574-1358110.1523/JNEUROSCI.4099-08.2008Crossref PubMed Scopus (349) Google Scholar). Moreover, activation of the Nrf2 pathway in astrocytes increases neuronal survival (25Vargas M.R. Johnson J.A. Astrogliosis in amyotrophic lateral sclerosis: role and therapeutic potential of astrocytes.Neurotherapeutics. 2010; 7 (20880509): 471-48110.1016/j.nurt.2010.05.012Crossref PubMed Scopus (94) Google Scholar). We recognized that this synergism between astrocytes and neurons resembles aspects of ANG-mediated neuroprotection. ANG is enriched in motor neurons and protects them against various ALS-related insults, such as excitotoxicity, hypoxia, and endoplasmic reticulum stress (7Kieran D. Sebastia J. Greenway M.J. King M.A. Connaughton D. Concannon C.G. Fenner B. Hardiman O. Prehn J.H. Control of motoneuron survival by angiogenin.J. Neurosci. 2008; 28 (19109488): 14056-1406110.1523/JNEUROSCI.3399-08.2008Crossref PubMed Scopus (136) Google Scholar, 27Sebastià J. Kieran D. Breen B. King M.A. Netteland D.F. Joyce D. Fitzpatrick S.F. Taylor C.T. Prehn J.H. Angiogenin protects motoneurons against hypoxic injury.Cell Death Differ. 2009; 16 (19444281): 1238-124710.1038/cdd.2009.52Crossref PubMed Scopus (88) Google Scholar, 28Cho G.-W. Kang B.Y. Kim S.H. Human angiogenin presents neuroprotective and migration effects in neuroblastoma cells.Mol. Cell Biochem. 2010; 340 (20174961): 133-14110.1007/s11010-010-0410-0Crossref PubMed Scopus (14) Google Scholar). These relationships provoked us to ask: Does ANG activate Nrf2? Here, we reveal that ANG does indeed activate the astrocytic Nrf2 pathway. Moreover, this activation transmits survival-promoting signals to proximal neurons, protecting them from oxidative stress. The Nrf2 pathway mediates the transcriptional induction of a battery of genes that comprise the antioxidant response system. We examined whether ANG activates Nrf2 in cultured cells that were derived from ARE–hPAP transgenic mice. Upon induction, the ARE drives hPAP expression, which increases the level of human placental alkaline phosphatase (hPAP). The phosphatase activity of hPAP was measured as a readout of Nrf2/ARE-dependent promoter activation (29Johnson D.A. Andrews G.K. Xu W. Johnson J.A. Activation of the antioxidant response element in primary cortical neuronal cultures derived from transgenic reporter mice.J. Neurochem. 2002; 81 (12068071): 1233-124110.1046/j.1471-4159.2002.00913.xCrossref PubMed Scopus (141) Google Scholar). tert-Butylhydroquinone (tBHQ) is a known inducer of Nrf2 and was used as positive control in these experiments (30Kraft A.D. Johnson D.A. Johnson J.A. 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.J. Neurosci. 2004; 24 (14762128): 1101-111210.1523/JNEUROSCI.3817-03.2004Crossref PubMed Scopus (456) Google Scholar). tBHQ increased hPAP activity to various extents, depending on the cell type. tBHQ treatment led to a 15-fold increase in hPAP activity in astrocytes (Fig. 1A) and only a 7-fold increase in neurons (Fig. 1C). Remarkably, in a mixed culture of astrocytes and neurons, hPAP activity was elevated by 249-fold (Fig. 1E), suggesting that cross-talk between neurons and astrocytes amplifies activation of the Nrf2 pathway. WT ANG activated hPAP comparably to tBHQ. Relative to vehicle, WT ANG induced the highest hPAP signal in a mixed culture, induced the second-highest signal in astrocytes, and caused no change in neurons (Fig. 1, B, D, and F). Moreover, the effect of ANG was dose-dependent, because ANG treatment at 5 μg/ml produced greater hPAP activity than at 1 μg/ml. To demonstrate signal specificity, we evaluated the phosphatase activity produced by ALS-associated ANG variants. As described previously (4Greenway M.J. Andersen P.M. Russ C. Ennis S. Cashman S. Donaghy C. Patterson V. Swingler R. Kieran D. Prehn J. Morrison K.E. Green A. Acharya K.R. Brown Jr., R.H. Hardiman O. ANG mutations segregate with familial and “sporadic” amyotrophic lateral sclerosis.Nat. Genet. 2006; 38 (16501576): 411-41310.1038/ng1742Crossref PubMed Scopus (572) Google Scholar, 31Shapiro R. Vallee B.L. Site-directed mutagenesis of histidine-13 and histidine-114 of human angiogenin: alanine derivatives inhibit angiogenin-induced angiogenesis.Biochemistry. 1989; 28 (2479414): 7401-740810.1021/bi00444a038Crossref PubMed Scopus (197) Google Scholar), H114R ANG is an inactive catalyst, S28N ANG is deficient in nuclear localization, and C39W ANG lacks conformational stability. None of these variants promoted hPAP gene expression (Fig. 1, B, D, and F). Next, we sought to demonstrate the intrinsic activation of ARE-dependent gene expression upon ANG treatment. Nrf2 induces the transcription of an array of antioxidant genes, and we selected three for analysis. NAD(P)H:quinone oxidoreductase 1 (NQO1) is involved in the reduction of quinones to hydroquinones to prevent redox cycling, which often generates free radicals (32Guo Y. Zhang Y. Wen D. Duan W. An T. Shi P. Wang J. Li Z. Chen X. Li C. The modest impact of transcription factor Nrf2 on the course of disease in an ALS animal model.Lab. Invest. 2013; 93 (23711824): 825-83310.1038/labinvest.2013.73Crossref PubMed Scopus (35) Google Scholar). Glutamate-cysteine ligase modifier subunit (GCLM) is part of the rate-limiting enzyme complex for the synthesis of GSH, a free radical scavenger (33Kanno T. Tanaka K. Yanagisawa Y. Yasutake K. Hadano S. Yoshii F. Hirayama N. Ikeda J.E. A novel small molecule, N-(4-(2-pyridyl)(1,3-thiazol-2-yl))-2-(2,4,6-trimethylphenoxy) acetamide, selectively protects against oxidative stress-induced cell death by activating the Nrf2–ARE pathway: therapeutic implications for ALS.Free Radic. Biol. Med. 2012; 53 (23000247): 2028-204210.1016/j.freeradbiomed.2012.09.010Crossref PubMed Scopus (47) Google Scholar). GSH S-transferase α4 (GSTα4) catalyzes the conjugation of reduced GSH to electrophilic substrates, detoxifying endogenous and xenobiotic alkylating agents (34Benedusi V. Martorana F. Brambilla L. Maggi A. Rossi D. The peroxisome proliferatoractivated receptor γ (PPARγ) controls natural protective mechanisms against lipid peroxidation in amyotrophic lateral sclerosis.J. Biol. Chem. 2012; 287 (22910911): 35899-3591110.1074/jbc.M112.366419Abstract Full Text Full Text PDF PubMed Scopus (48) Google Scholar). Using qPCR, we evaluated the expression of these antioxidant genes following treatment with ANG. In this experiment, tBHQ again served as a positive control. tBHQ treatment significantly up-regulated the expression of NQO1, GCLM, and GSTα4, consistent with the results of the reporter assay, in both neurons and astrocytes (Fig. 2, A and B). Consistent with the hPAP activity data, ANG activated Nrf2-dependent genes in astrocytes but not in neurons. Taken together, data from the reporter assay and on antioxidant gene expression indicate that WT ANG activates Nrf2-dependent gene expression. Then we asked whether Nrf2 is required for this ANG-mediated induction of gene expression. In WT astrocytes derived from ARE-hPAP reporter mice, there was a significant increase in hPAP activity with ANG treatment (Fig. 3A). This ANG-mediated increase was attenuated in cultures from ARE-hPAP/Nrf2−/− mice (Fig. 3B). As expected, none of the ANG variants increased hPAP activity in WT or Nrf2-deficient astrocytes. Further, the increase in NQO1 and GSTα4 expression following ANG treatment was reversed almost completely in Nrf2-deficient cultures (Fig. 3B). These results demonstrate that ANG-mediated changes are dependent on Nrf2. In astrocytes, ANG is internalized after it binds to syndecan-4, a transmembrane heparan sulfate proteoglycan (35Aparicio-Erriu I.M. Prehn J.H. Molecular mechanisms in amyotrophic lateral sclerosis: the role of angiogenin, a secreted RNase.Front. Neurosci. 2012; 6 (23181008): 167Crossref PubMed Scopus (27) Google Scholar, 36Skorupa A. King M.A. Aparicio I.M. Dussmann H. Coughlan K. Breen B. Kieran D. Concannon C.G. Marin P. Prehn J.H. Motoneurons secrete angiogenin to induce RNA cleavage in astroglia.J. Neurosci. 2012; 32 (22496549): 5024-503810.1523/JNEUROSCI.6366-11.2012Crossref PubMed Scopus (62) Google Scholar). To compete with the heparan sulfate–binding site within syndecan-4, we applied a saturating amount of heparin, which mimics heparan sulfate and is known to prevent the intracellular accumulation of ANG (37Yeo K.J. Hwang E. Min K.-M. Jee J.-G. Lee C.-K. Hwang K.Y. Jeon Y.H. Chang S.-I. Cheong H.-K. The dual binding site of angiogenin and its inhibition mechanism: the crystal structure of the rat angiogenin–heparin complex.Chem. Commun. (Camb.). 2014; 50 (25219815): 12966-1296910.1039/C4CC05175KCrossref PubMed Google Scholar). Pretreatment with heparin did indeed prevent the ANG-mediated increase hPAP activity (Fig. 3A). These data support the hypothesis that the binding of ANG to syndecan-4 is essential for activation of the Nrf2 pathway. As described above, Nrf2 is the master regulator of antioxidant responses (18Johnson D.A. Johnson J.A. Nrf2: a therapeutic target for the treatment of neurodegenerative diseases.Free Radic. Biol. Med. 2015; 88 (26281945): 253-26710.1016/j.freeradbiomed.2015.07.147Crossref PubMed Scopus (219) Google Scholar). Small-molecule Nrf2 activators can provide cells with powerful protection from oxidative damage (19Kanninen K.M. Pomeshchik Y. Leinonen H. Malm T. Koistinaho J. Levonen A.L. Applications of the Keap1–Nrf2 system for gene and cell therapy.Free Radic. Biol. Med. 2015; 88 (26164630): 350-36110.1016/j.freeradbiomed.2015.06.037Crossref PubMed Scopus (36) Google Scholar). Accordingly, tBHQ treatment protected cells from H2O2-mediated toxicity (Fig. 4, A, C, and E). The degree of protection did, however, vary among cell types; astrocytes were most responsive to tBHQ treatment, followed by a mixed culture, and then neurons. We note that WT ANG treatment likewise activated the Nrf2/ARE pathway (Figure 1, Figure 2, Figure 3). The robustness of activation appeared to correlate positively with the degree of cellular protection against H2O2-mediated toxicity (Fig. 4). As expected, WT ANG treatment protected astrocytes and a mixed culture less potently than did tBHQ (Fig. 4, B and F). Nonetheless, the protective effect of WT ANG in these cultures was significant. No protection was observed in neuronally enriched cultures (Fig. 4D). Once again, the data suggest that neuron–astrocyte communication is necessary to support neuronal survival against the deleterious consequences of oxidative stress. Previous studies have demonstrated that stressed neurons secrete ANG, which is then taken up by astrocytes (36Skorupa A. King M.A. Aparicio I.M. Dussmann H. Coughlan K. Breen B. Kieran D. Concannon C.G. Marin P. Prehn J.H. Motoneurons secrete angiogenin to induce RNA cleavage in astroglia.J. Neurosci. 2012; 32 (22496549): 5024-503810.1523/JNEUROSCI.6366-11.2012Crossref PubMed Scopus (62) Google Scholar). We replicated these findings, detecting a high level of secreted ANG in conditioned medium collected from neurons exposed to a low nontoxic dose of H2O2. Using a zymogram that provides a highly sensitive assessment of ribonucleolytic activity (38Bravo J. Fernández E. Ribó M. de Llorens R. Cuchillo C.M. A versatile negative-staining ribonuclease zymogram.Anal. Biochem. 1994; 219 (7520217): 82-8610.1006/abio.1994.1234Crossref PubMed Scopus (46) Google Scholar, 39Hoang T.T. Smith T.P. Raines R.T. A boronic acid conjugate of angiogenin that shows ROS-responsive neuroprotective activity.Angew. Chem. Int. Ed. Engl. 2017; 56 (28120377): 2619-262210.1002/anie.201611446Crossref PubMed Scopus (38) Google Scholar), we calibrated known ANG concentrations and the intensity of bands on a gel. Then we estimated that normal and stressed neuronal conditioned medium contained 0.5 and 4.0 μg of ANG/ml, respectively (Fig. 5A). Then we investigated how well stressed neurons are protected when treated with astrocytic conditioned medium that was pre-exposed to WT ANG. First, we treated astrocytes with 5 μg/ml of WT ANG or the inactive H114R variant. After 24 h, we collected the astrocytic conditioned medium and treated neurons with that medium for 24 h. The neurons were then subjected to H2O2-mediated toxicity. Only conditioned medium from astrocytes that were stimulated by WT ANG protected the neurons; conditioned medium from astrocytes exposed to the H114R ANG variant had no effect. Likewise, no change was observed from conditioned medium derived from Nrf2-deficient astrocytes, even upon stimulus with WT ANG (Fig. 5B). Members of the ptRNase superfamily have evolved to be efficient, nonspecific catalysts of RNA degradation (40Raines R.T. Ribonuclease A.Chem. Rev. 1998; 98 (11848924): 1045-106610.1021/cr960427hCrossref PubMed Scopus (855) Google Scholar). Unlike its homologs, ANG has nearly unmeasurable ribonucleolytic activity toward model substrates (41Curran T.P. Shapiro R. Riordan J.F. Alteration of the enzymatic specificity of human angiogenin by site-directed mutagenesis.Biochemistry. 1993; 32 (8095159): 2307-231310.1021/bi00060a023Crossref PubMed Scopus (61) Google Scholar, 42Leland P.A. Staniszewski K.E. Park C. Kelemen B.R. Raines R.T. The ribonucleolytic activity of angiogenin.Biochemistry. 2002; 41 (11802736): 1343-135010.1021/bi0117899Crossref PubMed Scopus (47) Google Scholar). Moreover, whereas other ptRNases function in the extracellular space, ANG acts within cells (43Moroianu J. Riordan J.F. Nuclear translocation of angiogenin in proliferating endothelial cells is essential to its angiogenic activity.Proc. Natl. Acad. Sci. U.S.A. 1994; 91 (8127865): 1677-168110.1073/pnas.91.5.1677Crossref PubMed Scopus (248) Google Scholar, 44Kishimoto K. Liu S. Tsuji T. Olson K.A. Hu G.-F. Endogenous angiogenin in endothelial cells is a general requirement for cell proliferation and angiogenesis.Oncogene. 2005; 24 (15558023): 445-45610.1038/sj.onc.1208223Crossref PubMed Scopus (273) Google Scholar, 45Hoang T.T. Raines R.T. Molecular basis for the autonomous promotion of cell proliferation by angiogenin.Nucleic Acids Res. 2017; 45 (27915233): 818-83110.1093/nar/gkw1192Crossref PubMed Scopus (29) Google Scholar, 46Thomas S.P. Hoang T.T. Ressler V.T. Raines R.T. Human angiogenin is a potent cytotoxin in the absence of ribonuclease inhibitor.RNA. 2018; 24 (29748193): 1018-102710.1261/rna.065516.117Crossref PubMed Scopus (28) Google Scholar). Previous studies have shown that ANG cleaves tRNA to mediate neuroprotective activity (10Yamasaki S. Ivanov P. Hu G.-F. Anderson P. Angiogenin cleaves tRNA and promotes stress-induced translational repression.J. Cell Biol. 2009; 185 (19332886): 35-4210.1083/jcb.200811106Crossref PubMed Scopus (599) Google Scholar, 11Ivanov P. Emara M.M. Villen J. Gygi S.P. Anderson P. Angiogenin-induced tRNA fragments inhibit translation initiation.Mol. Cell. 2011; 43 (21855800): 613-62310.1016/j.molcel.2011.06.022Abstract Full Text Full Text PDF PubMed Scopus (611) Google Scholar12Ivanov P. O'Day E. Emara M.M. Wagner G. Lieberman J. Anderson P. G-quadruplex structures contribute to the neuroprotective effects of angiogenin-induced tRNA fragments.Proc. Natl. Acad. Sci. U.S.A. 2014; 111 (25404306): 18201-1820610.1073/pnas.1407361111Crossref PubMed Scopus (207) Google Scholar). Most ANG mutations that segregate with ALS do not significantly alter the secondary structure or conformational stability of ANG. Instead, they disrupt its ribonucleolytic activity or subcellular distribution (47Crabtree B. Thiyagarajan N. Prior S.H. Wilson P. Iyer S. Ferns T. Shapiro R. Brew K. Subramanian V. Acharya K.R. Characterization of human angiogenin variants implicated in amyotrophic lateral sclerosis.Biochemistry. 2007; 46 (17900154): 11810-1181810.1021/bi701333hCrossref PubMed Scopus (86) Google Scholar48Thiyagarajan N. Ferguson R. Subramanian V. Acharya K.R. Structural and molecular insights into the mechanism of action of human angiogenin-ALS variants in neurons.Nat. Commun. 2012; 3 (23047679): 112110.1038/ncomms2126Crossref PubMed Scopus (67) Google Scholar, 49Padhi A.K. Jayaram B. Gomes J. Prediction of functional loss of human angiogenin mutants associated with ALS by molecular dynamics simulations.Sci. Rep. 2013; 3 (23393617): 122510.1038/srep01225Crossref PubMed Scopus (39) Google Scholar50Padhi A.K. Banerjee K. Gomes J. Banerjee M. Computational and functional characterization of angiogenin mutations, and correlation with amyotrophic lateral sclerosis.PLoS One. 2014; 9 (25372031): e11196310.1371/journal.pone.0111963Crossref PubMed Scopus (12) Google Scholar). This observation has stimulated interest in understanding the molecular basis of the role of ANG in neuroprotection. We find that ANG activates the Nrf2 pathway in astrocytes and that this activation protects neurons from oxidative injury. In this mechanism of action (Fig. 6), stressed neurons secrete high levels of ANG, which then binds to syndecan-4 receptors on astrocytes and enters the astrocytes via endocytosis (51Ferguson R. Subramanian V. The cellular uptake of angiogenin, an angiogenic and neurotrophic factor is through multiple pathways and largely dynamin independent.PLoS One. 2018; 13 (29486010): e019330210.1371/journal.pone.0193302Crossref PubMed Scopus (14) Google Scholar). The binding of ANG to the receptor activates PKCα, which phosphorylates Nrf2, endowing it with the ability to evade the Keap1 inhibitor (52Huang H.C. Nguyen T. Pickett C.B. Phosphorylation of Nrf2 at Ser-40 by protein kinase C regulates antioxidant response element-mediated transcription.J. Biol. Chem. 2002; 277 (12198130): 42769-4277410.1074/jbc.M206911200Abstract Full Text Full Text PDF PubMed Scopus (820) Google Scholar). Phosphorylated Nrf2 translocates to the nucleus and forms heterodimers with Maf. These dimers bind to AREs to stimulate antioxidant gene expression that defends against H2O2-mediated toxicity. A fraction of the ANG in endosomes escapes into the cytosol. Cytosolic ANG is sequestered in granules through the recruitment of 5′-tiRNAs, which are produced by the ANG-mediated cleavage of tRNAs (9Lyons S.M. Fay M.M. Akiyama Y. Anderson P.J. Ivanov P. RNA biology of angiogenin: current state and perspectives.RNA Biol. 2017; 14 (28010172): 171-17810.1080/15476286.2016.1272746Crossref PubMed Scopus (74) Google Scholar). These tiRNAs interact with the translational silencer protein YB-1 and sequester the eukaryotic translation initiation factor" @default.
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• W2969790734 title "Angiogenin activates the astrocytic Nrf2/antioxidant-response element pathway and thereby protects murine neurons from oxidative stress" @default.
• W2969790734 cites W1166587220 @default.
• W2969790734 cites W119489668 @default.
• W2969790734 cites W1483389620 @default.
• W2969790734 cites W1797572428 @default.
• W2969790734 cites W1810319741 @default.
• W2969790734 cites W1966699402 @default.
• W2969790734 cites W1968051733 @default.
• W2969790734 cites W1970642506 @default.
• W2969790734 cites W1978352522 @default.
• W2969790734 cites W1986099314 @default.
• W2969790734 cites W1988176449 @default.
• W2969790734 cites W1993981661 @default.
• W2969790734 cites W1994461542 @default.
• W2969790734 cites W2000683840 @default.
• W2969790734 cites W2002799732 @default.
• W2969790734 cites W2004922096 @default.
• W2969790734 cites W2009517899 @default.
• W2969790734 cites W2016123870 @default.
• W2969790734 cites W2019153476 @default.
• W2969790734 cites W2019203771 @default.
• W2969790734 cites W2023556666 @default.
• W2969790734 cites W2026406888 @default.
• W2969790734 cites W2027085316 @default.
• W2969790734 cites W2027742580 @default.
• W2969790734 cites W2028484915 @default.
• W2969790734 cites W2040773899 @default.
• W2969790734 cites W2044154503 @default.
• W2969790734 cites W2052548231 @default.
• W2969790734 cites W2053063855 @default.
• W2969790734 cites W2055296375 @default.
• W2969790734 cites W2056831129 @default.
• W2969790734 cites W2063183749 @default.
• W2969790734 cites W2068058352 @default.
• W2969790734 cites W2068332602 @default.
• W2969790734 cites W2069493167 @default.
• W2969790734 cites W2073666328 @default.
• W2969790734 cites W2073688363 @default.
• W2969790734 cites W2079195332 @default.
• W2969790734 cites W2089744682 @default.
• W2969790734 cites W2094088429 @default.
• W2969790734 cites W2109140791 @default.
• W2969790734 cites W2116163367 @default.
• W2969790734 cites W2128457767 @default.
• W2969790734 cites W2134135259 @default.
• W2969790734 cites W2165201727 @default.
• W2969790734 cites W2185348657 @default.
• W2969790734 cites W2195247023 @default.
• W2969790734 cites W2246949337 @default.
• W2969790734 cites W2254572992 @default.
• W2969790734 cites W2274550965 @default.
• W2969790734 cites W2556818673 @default.
• W2969790734 cites W2560154437 @default.
• W2969790734 cites W2562613588 @default.
• W2969790734 cites W2580035316 @default.
• W2969790734 cites W2582305699 @default.
• W2969790734 cites W2789570440 @default.
• W2969790734 cites W2800397674 @default.
• W2969790734 cites W4211216439 @default.
• W2969790734 cites W4239117141 @default.
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