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Molecular Medicine |
From the Department of Clinical and Experimental Medicine, University Magna Græcia of Catanzaro, Italy.
Correspondence to Francesco Perticone, Dipartimento di Medicina Sperimentale e Clinica "Gaetano Salvatore," Via Tommaso Campanella, 115, 88100 Catanzaro, Italy. E-mail perticone{at}unicz.it
| Abstract |
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Key Words: endothelium angiotensin II nitric oxide insulin
| Introduction |
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| Materials and Methods |
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Phosphospecific Phosphorylation of IRS-1, Association of IRS-1 With the p85 Subunit of PI 3-Kinase, Akt, and eNOS Phosphorylation
Human umbilical vein endothelial cells (HUVECs) were cultured for 18 hours in serum-deprived medium containing 10 mmol/L glucose and incubated for 30 minutes in the presence or absence of 100 nmol/L AII followed by stimulation with 100 nmol/L insulin for the indicated periods of time. In experiments with losartan, this was added to cells 30 minutes before AII addition. HUVECs were lysed in buffer containing 50 mmol/L HEPES (pH 7.5), 150 mmol/L NaCl, 10 mmol/L EDTA, 1% Triton X-100, 10 mmol/L Na4P2O7, 100 mmol/L NaF, and 2 mmol/L sodium orthovanadate supplemented with protease inhibitor cocktail. Insoluble material was removed by centrifugation, and equal amounts of supernatants were incubated with anti-IRS-1 antibody. Immune complexes were collected by incubation with protein A Sepharose for 2 hours at 4°C and resuspended in Laemmeli buffer. Cell lysates or immunoprecipitated proteins were subjected to SDS-PAGE under reducing conditions. Proteins resolved by SDS-PAGE were electrophoretically transferred to nitrocellulose membrane. The membranes were incubated with primary anti-phosphospecific, anti-p85 subunit of PI 3-kinase, anti-Ser473 Akt, anti-Thr308 Akt, or anti-Ser1177-eNOS antibodies followed by incubation with peroxidase-conjugated secondary antibodies. Proteins were detected by using enhanced chemiluminescence, and band densities were quantified by densitometry. To normalize the blots for protein levels, after being immunoblotted with anti-phosphospecific antibodies, the blots were stripped and reprobed with appropriate primary antibodies.
AII-Induced Serine Phosphorylation of IRS-1, Phosphorylation of ERK1/2 and JNK, and ERK1/2 Activity
HUVECs were cultured for 18 hours in serum-deprived medium and incubated for 30 minutes in the presence or absence of 100 nmol/L AII, 100 nmol/L insulin, or a combination of the two hormones. In experiments with losartan, cell-permeable inhibitor of JNK (20 µmol/L), or PD98059 (50 nmol/L), these were added to cells 30 minutes before hormone addition. Equal amounts of cell lysates were incubated with anti-IRS-1 antibody, and immune complexes were collected by protein A Sepharose. Cell lysates or immunoprecipitated proteins were resolved by SDS-PAGE, transferred to nitrocellulose membrane, and immunoblotted with anti-Ser312-IRS-1, anti-Ser616-IRS-1, anti-phospho-ERK1/2, or anti-phospho JNK antibodies. To normalize the blots for protein levels, after being immunoblotted with anti-phosphospecific antibodies, the blots were stripped and reprobed with anti-IRS-1, anti-ERK1/2, or anti-JNK antibody. For determination of ERK1/2 activity, the cells lysates were incubated with anti-ERK-1/2 antibody at 4°C overnight and immune complexes were collected by protein A Sepharose. After washing, the immunoprecipitates were suspended in a reaction buffer containing 20 µmol/L ATP, 10 µCi/sample of [
-32P] ATP (6000 Ci/mmol), and 0.25 mg/mL myelin basic protein. The suspension was incubated with agitation at 30°C for 45 minutes. The reaction was terminated by transferring 25-µL aliquots onto P-81 phosphocellulose paper discs and washed in 0.75% H3PO4. The discs were washed once with acetone and air-dried, and the 32P incorporated into myelin basic protein was measured by liquid scintillation counting. Specific kinase activity was determined by subtracting the radioactivity in the absence of substrate from that in the presence of substrate. Western blotting was performed on a portion of the immunoprecipitates, and the radioactivity was normalized for ERK1/2 content.
eNOS Activity
HUVECs were serum-starved for 18 hours and incubated in the presence or absence of the indicated hormones and inhibitors. The amount of NOS activity produced by HUVECs was assayed using an NOS Detection System (Sigma, Saint Louis, Mo) that measures the ability of NOS to convert L-14C-arginine (Amersham) to L-14C-citrulline, according to the manufacturers instructions.4 Data were normalized by the amount of protein and reaction time.
Statistical Analysis
All results are given as mean±SE and were analyzed with the use of the Newman-Keuls test for ANOVA for multiple comparisons. P<0.05 was considered statistically significant.
| Results |
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Effects of AII on Insulin-Stimulated Tyrosine Phosphorylation of IRS-1 and IRS-1/PI 3-Kinase Docking
Because prior studies in rat aortic smooth muscle cells have shown that treatment with AII (100 nmol/L) inhibited insulin-stimulated tyrosine phosphorylation of IRS-1 and its ability to engage PI 3-kinase,8 we tested whether AII would affect insulin signaling in human endothelial cells. As shown in Figure 3A, exposure of HUVECs to AII resulted in a time-dependent inhibition of insulin-stimulated tyrosine phosphorylation of IRS-1, with maximal effect occurring after 30 minutes of incubation. Therefore, subsequent experiments aimed at studying the inhibitory effect of AII on insulin signaling were performed with HUVECs exposed to AII for 30 minutes, a time at which AII exerted both its maximal stimulatory effect on IRS-1 phosphorylation at both Ser312 and Ser616 and its maximal inhibitory effect on insulin-stimulated tyrosine phosphorylation of IRS-1. Losartan reversed the inhibitory effect of AII in a dose-dependent manner, with maximal effect occurring at 200 nmol/L (Figure 3B). AII did not significantly alter basal tyrosine phosphorylation of IRS-1 or levels of expressed IRS-1 (Figures 3A and 4
A). Nonimmune serum did not lead to immunoprecipitation of IRS-1, thus indicating that IRS-1 immunoprecipitation by anti-IRS-1 antibody was specific (Figure 4A). Because association of the p85 regulatory subunit of PI 3-kinase with tyrosine-phosphorylated IRS-1 is essential to promote downstream signaling, the effect of AII on IRS-1/p85 docking was examined by immunoprecipitation of IRS-1 from cell lysates followed by immunoblotting with anti-p85 antibody. Insulin stimulated by 1.7-fold the binding of IRS-1 to p85 subunit (P<0.01) (Figure 4B). AII treatment reduced by 30% insulin-stimulated binding of IRS-1 to p85 subunit (P<0.02). This inhibitory effect of AII on IRS-1/p85 association was reversed by losartan (Figure 4B). There is evidence that tyrosine residues in the YXXM motifs at positions 612 and 632 (Tyr612 and Tyr632) play a major role in engaging the tandem SH2 domains of p85 subunit of PI 3-kinase, thus allowing for its full activation.20 To test the possibility that impaired IRS-1/p85 association induced by AII was related to changes in phosphorylation states of these two YXXM motifs, IRS-1 was immunoprecipitated from cell lysates and immunoblotted with phosphospecific anti-Tyr612 or anti-Tyr632 IRS-1 antibody. Insulin stimulated by
3-fold phosphorylation of Tyr612 and Tyr632 on IRS-1 (P<0.01) (Figures 4C and 4D, respectively). AII treatment reduced by 40% insulin-stimulated phosphorylation of Tyr612 and Tyr632 (P<0.02). The inhibitory effect of AII on phosphorylation of Tyr612 and Tyr632 was reversed by losartan. Thus, these data indicate that AII inhibits tyrosine phosphorylation on IRS-1 sites necessary for p85 binding. Previous studies have shown that hyper-Ser phosphorylation of IRS-1 converts IRS-1 in an inhibitor of the intrinsic insulin receptor tyrosine kinase.17 To test the possibility that increased Ser phosphorylation of IRS-1 induced by AII was associated with impaired insulin-stimulated tyrosine phosphorylation of the receptor, the insulin receptor was immunoprecipitated from cell lysates and immunoblotted with anti-Tyr1158/Tyr1162/Tyr1163 phospho-specific antibody directed to the active loop of the catalytic domain of the insulin receptor. Insulin stimulated by
4-fold tyrosine phosphorylation of the insulin receptor (P<0.002) (Figure 4E). AII treatment reduced by 65% insulin-stimulated Tyr1158/Tyr1162/Tyr1163 phosphorylation of the receptor (P<0.005). Nonimmune serum did not lead to immunoprecipitation of the insulin receptor, thus indicating that immunoprecipitation of the insulin receptor by anti-IR antibody was specific (Figure 4E). The inhibitory effect of AII on Tyr1158/Tyr1162/Tyr1163 phosphorylation of the insulin receptor was reversed by losartan.
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Effects of AII on Insulin-Stimulated Activation of Akt and eNOS
Evidence has been provided indicating that insulin regulates NO production via a pathway involving PI-3 kinasedependent activation of Akt, which in turn leads to phosphorylation of eNOS on serine 1177.21,22 Therefore, we tested whether AII would affect insulin-stimulated Akt/eNOS activation. Insulin stimulated by 3-fold Ser473 Akt phosphorylation (P<0.01) and by 2.5-fold Thr308 Akt phosphorylation (P<0.01) (Figures 5A and 5B). AII treatment reduced by 60% insulin-stimulated Ser473 Akt activation (P<0.01) and by 85% Thr308 activation. These inhibitory effects of AII were reversed by losartan (Figures 5A and 5B). AII did not affect Akt expression, as detected by immunoblotting (Figures 5A and 5B). Insulin increased by
3-fold phosphorylation of eNOS on Ser1177 (P<0.01) (Figure 5C). AII treatment resulted in a significant decrease (45%) of insulin-stimulated Ser1177 eNOS phosphorylation (P<0.01), whereas it did not affect eNOS expression (Figure 5C). The inhibitory effect of AII was reversed by losartan.
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Effects of AII on Insulin-Stimulated NO Production
To additionally demonstrate that JNK and ERK1/2 play a negative role in insulin-stimulated NO production and that their activation is required for AII-mediated insulin resistance, we decided to determine whether JNK and MEK1 inhibitors can reverse AII-induced impairment in both activation of the Akt/eNOS pathway and NO production in response to insulin. As shown in Figures 6A and 6B, treatment of HUVECs with JNK inhibitor or PD98059 reversed the inhibitory effects of AII on insulin-stimulated phosphorylation of both Akt at Ser472 and eNOS at Ser1177. Insulin-stimulated NO production was reduced by AII in a dose-dependent manner (Figure 6C). The same dose-response relationship was observed for AII-induced IRS-1 phosphorylation at both Ser312 and Ser616, respectively (Figure 6D). The inhibitory effect of AII on insulin-stimulated NO production was reversed by losartan (Figure 6C). Treatment of HUVECs with JNK inhibitor or PD98059 reversed the inhibitory effect of AII, causing an increase of up to 80% and 55%, respectively, of NO production stimulated by insulin in the absence of AII, whereas simultaneous incubation with both inhibitors completely restored the stimulatory effects of insulin (Figure 6C). These data are consistent with the idea that AII-induced inhibition of the stimulatory effects of insulin on NO production is mediated, at least in part, through IRS-1 phosphorylation at Ser312 and Ser616 induced by JNK and ERK1/2, respectively, which negatively affects the downstream signaling pathway involving PI 3-kinase/Akt/eNOS.
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| Discussion |
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The impaired activation in response to insulin of the IRS-1/PI 3-kinase/Akt/eNOS signaling pathway in HUVECs exposed to AII was not attributable to alterations in IRS-1, p85, Akt, or eNOS protein levels but rather to a reduced phosphorylation of IRS-1 at tyrosine 612 and 632, which play a major role in the binding of IRS-1 with the SH2 domains of the p85 regulatory subunit of PI 3-kinase. A growing body of evidence indicates that serine phosphorylation of IRS-1 induced by a variety of factors interferes with the ability of this substrate to be tyrosine phosphorylated on insulin stimulation and reduces its ability to engage the p85 subunit of PI 3-kinase. More recently, several specific serine phosphorylation sites in IRS-1 and the corresponding activating kinases have been identified as responsible for these inhibitory effects.1317 Activation of JNK has been shown to result in stimulation of Ser312 of IRS-1, whereas activation of ERK1/2 has been shown to result in an increased phosphorylation of Ser612. Because AII activates both ERK1/2 and JNK in cultured vascular smooth muscle cells as well as in intact arteries,18,19 we examined the possibility that AII-induced phosphorylation at Ser312 and Ser616 of IRS-1 mediated by JNK and ERK1/2, respectively, may account for the inhibitory effects of AII on insulin signaling pathway involved in NO production. We found that HUVECs exposed to AII exhibited increased JNK and ERK1/2 activity, which was associated with a concomitant increase in IRS-1 phosphorylation on Ser312 and Ser616, respectively. Interestingly, losartan inhibited the stimulatory effects of AII on JNK and ERK1/2 activity and reverted the enhanced Ser312 and Ser616 phosphorylation of IRS-1 stimulated by AII. We additionally demonstrated the cause-effect relationship between these two events by using inhibitors of JNK and MEK1. Indeed, we found that inhibition of JNK and MEK1 activity partly reversed the negative effects of AII on insulin-stimulated NO production, whereas the combined inhibition of JNK and MEK1 activity fully restored the stimulatory effects of insulin. Obviously we cannot exclude the possibility that other serine kinases may phosphorylate IRS-1 under the conditions used in the present study, leading to impairment in the activation of downstream events of insulin signaling pathway. Furthermore, it is possible that the inhibitory effects of AII on insulin-stimulated NO production is independent of IRS-1 serine phosphorylation and is partially related to an ERK1/2-dependent eNOS phosphorylation, leading to inhibition of the enzyme, as suggested by a recent study.29 Notwithstanding these possibilities, the present results suggest that AII-induced activation of JNK and ERK1/2 might be an important negative regulator for the insulin pathway involved in NO production.
In summary, we show that AII acting via the AT1 receptor exerts an inhibitory effect on the insulin signaling pathway involved in NO production and, for the first time, correlate these changes with activation of JNK and ERK1/2. Our data suggest that the uncoupling of IRS-1 and PI 3-kinase in AII-treated HUVECs may be linked to an increased phosphorylation at Ser312 and Ser616 of IRS-1 mediated by JNK and ERK1/2, respectively. These changes are associated with a concomitant reduction in phosphorylation of Tyr612 and Tyr632 in two YXXM motifs essential for engaging p85 regulatory subunit of PI 3-kinase, resulting in impairment in activation of IRS-1associated PI 3-kinase and sequential activation of the Akt/eNOS pathway.
In conclusion, increasing evidence suggests that the vasculature is an insulin-responsive tissue and that one of the major vascular actions of insulin is its vasodilatory effect, which is mediated by enhanced production of NO. AII-induced insulin resistance in endothelial cells may play an important role in the pathophysiology of cardiovascular disease associated with hypertension and insulin resistance. The characterization of the molecular mechanism involved in AII-induced insulin resistance in the endothelium provides an important mechanistic link implicating JNK and ERK1/2 in the inhibitory effect of AII on insulin vascular action and may help to design efficacious pharmacological molecules to treat endothelial dysfunction associated with insulin resistance states.
| Acknowledgments |
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| Footnotes |
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| References |
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2. Balletshofer BM, Rittig K, Enderle MD, Volk A, Maerker E, Jacob S, Matthaei S, Rett K, Haring HU. Endothelial dysfunction is detectable in young normotensive first-degree relatives of subjects with type 2 diabetes in association with insulin resistance. Circulation. 2000; 101: 17801784.
3. Perticone F, Ceravolo R, Pujia A, Ventura G, Iacopino S, Scozzafava A, Ferraro A, Chello M, Mastroroberto P, Verdecchia P, Schillaci G. Prognostic significance of endothelium dysfunction in hypertensive patients. Circulation. 2001; 104: 191196.
4. Federici M, Menghini R, Mauriello A, Hribal ML, Ferrelli F, Lauro D, Sbraccia P, Spagnoli LG, Sesti G, Lauro R. Insulin-dependent activation of endothelial nitric oxide synthase is impaired by O-linked glycosylation modification of signaling proteins in human coronary endothelial cells. Circulation. 2002; 106: 466472.
5. Mancini GB, Henry GCH, Macaya C, ONeill BJ, Pucillo AL, Carere RG, Wargovich TJ, Mudra H, Luscher TF, Klibaner MI, Haber HE, Uprichard AC, Pepine CJ, Pitt B. Angiotensin-converting enzyme inhibition with quinapril improves endothelial vasomotor dysfunction in patients with coronary artery disease: the TREND (Trial on Reversing Endothelial Dysfunction) study. Circulation. 1996; 94: 258265.
6. Cheetham C, Collis J, ODriscoll G, Stanton K, Taylor R, Green D. Losartan, an angiotensin type 1 receptor antagonist, improves endothelial function in non-insulin-dependent diabetes. J Am Coll Cardiol. 2000; 36: 14611466.
7. ODriscoll JG, Green DJ, Maiorana A, Stanton K, Colreavy F, Taylor RR. Improvement in endothelial function by ACE inhibition in non-insulin-dependent diabetes mellitus. J Am Coll Cardiol. 1999; 33: 15061511.
8. Zeng G, Nystrom FH, Ravichandran LV, Cong LN, Kirby M, Mostowski H, Quon MJ. Roles for insulin receptor, PI3-kinase, and Akt in insulin-signaling pathways related to production of nitric oxide in human vascular endothelial cells. Circulation. 2000; 101: 15391545.
9. Folli F, Kahn CR, Hansen H, Bouchie JL, Feener EP. Angiotensin II inhibits insulin signaling in aortic smooth muscle cells at multiple levels: a potential role for serine phosphorylation in insulin/angiotensin II crosstalk. J Clin Invest. 1997; 100: 21582169.[Medline] [Order article via Infotrieve]
10. Paolisso G, Tagliamonte MR, Gambardella A, Manzella D, Gualdiero P, Varricchio G, Verza M, Varricchio M. Losartan mediated improvement in insulin action is mainly due to an increase in non-oxidative glucose metabolism and blood flow in insulin-resistant hypertensive patients. J Hum Hypertens. 1997; 11: 307312.[CrossRef][Medline] [Order article via Infotrieve]
11. Henriksen EJ, Jacob S, Kinnick TR, Teachey MK, Krekler M. Selective angiotensin II receptor antagonism reduces insulin resistance in obese Zucker rats. Hypertension. 2001; 38: 884890.
12. Nawano M, Anai M, Funaki M, Kobayashi H, Kanda A, Fukushima Y, Inukai K, Ogihara T, Sakoda H, Onishi Y, Kikuchi M, Yazaki Y, Oka Y, Asano T. Imidapril, an angiotensin-converting enzyme inhibitor, improves insulin sensitivity by enhancing signal transduction via insulin receptor substrate proteins and improving vascular resistance in the Zucker fatty rat. Metabolism. 1999; 48: 12481255.[CrossRef][Medline] [Order article via Infotrieve]
13. De Fea K, Roth RA. Modulation of insulin receptor substrate-1 tyrosine phosphorylation and function by mitogen-activated protein kinase. J Biol Chem. 1997; 272: 3140031406.
14. De Fea K, Roth RA. Protein kinase C modulation of insulin receptor substrate-1 tyrosine phosphorylation requires serine 612. Biochemistry. 1997; 36: 1293912947.[CrossRef][Medline] [Order article via Infotrieve]
15. Aguirre V, Uchida T, Yenush L, Davis R, White MF. The c-Jun NH2-terminal kinase promotes insulin resistance during association with insulin receptor substrate-1 and phosphorylation of Ser307. J Biol Chem. 2000; 275: 90479054.
16. Aguirre V, Werner ED, Giraud J, Lee YH, Shoelson SE, White MF. Phosphorylation of Ser307 in insulin receptor substrate-1 blocks interactions with the insulin receptor and inhibits insulin action. J Biol Chem. 2002; 277: 15311537.
17. Hotamisligil GS, Peraldi P, Budavari A, Ellis R, White MF, Spiegelman BM. IRS-1-mediated inhibition of insulin receptor tyrosine kinase activity in TNF-
- and obesity-induced insulin resistance. Science. 1996; 271: 665668.[Abstract]
18. Touyz RM, Schiffrin EL. Signal transduction mechanisms mediating the physiological and pathophysiological actions of angiotensin II in vascular smooth muscle cells. Pharmacol Rev. 2000; 52: 639672.
19. Kudoh S, Komuro I, Mizuno T, Yamazaki T, Zou Y, Shiojima I, Takekoshi N, Yazaki Y. Angiotensin II stimulates c-Jun NH2-terminal kinase in cultured cardiac myocytes of neonatal rats. Circ Res. 1997; 80: 139146.
20. Esposito DL, Li Y, Cama A, Quon MJ. Tyr612 and Tyr632 in human insulin receptor substrate-1 are important for full activation of insulin-stimulated phosphatidylinositol 3-kinase activity and translocation of GLUT4 in adipose cells. Endocrinology. 2001; 142: 28332840.
21. Fulton D, Gratton JP, McCabe TJ, Fontana J, Fujio Y, Walsh K, Franke TF, Papapetropoulos A, Sessa WC. Regulation of endothelium-derived nitric oxide production by the protein kinase Akt. Nature. 1999; 399: 597601.[CrossRef][Medline] [Order article via Infotrieve]
22. Dimmeler S, Fleming I, Fisslthaler B, Hermann C, Busse R, Zeiher AM. Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation. Nature. 1999; 399: 601605.[CrossRef][Medline] [Order article via Infotrieve]
23. Dugourd C, Gervais M, Corvol P, Monnot C. Akt is a major downstream target of PI3-kinase involved in angiotensin IIinduced proliferation. Hypertension. 2003; 41: 882890.
24. Tian B, Liu J, Bitterman P, Bache RJ. Angiotensin II modulates nitric oxide-induced cardiac fibroblast apoptosis by activation of AKT/PKB. Am J Physiol Heart Circ Physiol. 2003; 285: H1105H1112.
25. Gorin Y, Kim N-H, Feliers D, Bhandari B, Choudhury GG, Abboud HE. Angiotensin II activates Akt/protein kinase B by arachidonic acid/redox-dependent pathway and independent of phosphoinositide 3-kinase. FASEB J. 2001; 15: 19091920.
26. Motley ED, Eguchi K, Gardner C, Hicks AL, Reynolds CM, Frank GD, Mifune M, Ohba M, Eguchi S. Insulin-induced Akt activation is inhibited by angiotensin II in the vasculature through protein kinase C-
. Hypertension. 2003; 41 (part 2): 775780.
27. Jiang ZY, Lin Y-W, Clemont A, Feener EP, Hein KD, Igarashi M, Yamauchi T, White MF, King GL. Characterization of selective resistance to insulin signaling in the vasculature of obese Zucker (fa/fa) rats. J Clin Invest. 1999; 104: 447457.[Medline] [Order article via Infotrieve]
28. Zecchin HG, Bezerra RM, Carvalheira JB, Carvalho-Filho MA, Metze K, Franchini KG, Saad MJ. Insulin signalling pathways in aorta and muscle from two animal models of insulin resistance-the obese middle-aged and the spontaneously hypertensive rats. Diabetologia. 2003; 46: 479491.[Medline] [Order article via Infotrieve]
29. Bernier SG, Haldar S, Michel T. Bradykinin-regulated interactions of the mitogen-activated protein kinase pathway with the endothelial nitric-oxide synthase. J Biol Chem. 2000; 275: 3070730715.
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