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Circulation Research. 2005;97:1115-1123
Published online before print October 20, 2005, doi: 10.1161/01.RES.0000191538.76771.66
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(Circulation Research. 2005;97:1115.)
© 2005 American Heart Association, Inc.


Molecular Medicine

Nitric Oxide Regulates Transforming Growth Factor-ß Signaling in Endothelial Cells

Marta Saura, Carlos Zaragoza, Beatrice Herranz, Mercedes Griera, Luisa Diez-Marqués, Diego Rodriguez-Puyol, Manuel Rodriguez-Puyol

From the Departmento Fisiología (M.S., B.H., M.G., L.D.-M., M.R.-P.), Universidad de Alcalá, Alcalá de Henares; Nefrología (D.R.-P.), Hospital Príncipe de Asturias, Alcalá de Henares; and Centro Nacional de Investigaciones Cardiovasculares (C.Z.), Madrid, Spain.

Correspondence to Dr Marta Saura, Autovía Madrid-Barcelona Km 33,500, Alcalá de Henares, 28871 Madrid, Spain. E-mail marta.saura{at}uah.es


*    Abstract
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*Abstract
down arrowIntroduction
down arrowMaterials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Many forms of vascular disease are characterized by increased transforming growth factor (TGF)-ß1 expression and endothelial dysfunction. Smad proteins are a key step in TGF-ß–initiated signal transduction. We hypothesized that NO may regulate endothelial TGF-ß–dependent gene expression. We show that NO inhibits TGF-ß/Smad–regulated gene transactivation in a cGMP-dependent manner. NO effects were mimicked by a soluble analogue of cGMP. Inhibition of cGMP-dependent protein kinase 1 (PKG-1) or overexpression of dominant-negative PKG-1{alpha} suppressed NO/cGMP inhibition of TGF-ß–induced gene expression. Inversely, overexpression of PKG-1{alpha} catalytic subunit blocked TGF-ß–induced gene transactivation. Furthermore NO delayed and reduced phosphorylated Smad2/3 nuclear translocation, an effect mediated by PKG-1, whereas NG-nitro-L-arginine methyl ester augmented Smad phosphorylation and gene expression in response to TGF-ß. Aortas from endothelial NO synthase–deficient mice showed enhanced basal TGF-ß1 and collagen type I expression; endothelial cells from these animals showed increased Smad phosphorylation and transcriptional activity. Proteasome inhibitors prevented the inhibitory effect of NO on TGF-ß signaling. NO reduced the metabolic life of ectopically expressed Smad2 and enhanced its ubiquitination. Taken together, these results suggest that the endothelial NO/cGMP/PKG pathway interferes with TGF-ß/Smad2 signaling by directing the proteasomal degradation of activated Smad.


Key Words: nitric oxide • endothelial cells • vascular remodeling • transforming growth factor-ß


*    Introduction
up arrowTop
up arrowAbstract
*Introduction
down arrowMaterials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Transforming growth factor (TGF)-ß plays a major role in the vascular response to injury by controlling both cellular proliferation and extracellular matrix turnover through the Smad-signaling pathway.1–3 Ligand binding leads to phosphorylation and nuclear translocation of receptor-activated Smads (R-Smads), Smad2/3, which modulate the transcription of a large number of genes. Smad7 and Smad6, inhibitory Smads (I-Smad), antagonize TGF-ß signaling. Smad7/6 expression is induced by TGF-ß in the endothelium, providing an autoregulatory negative feedback loop on TGF-ß signaling.4

The response to TGF-ß in the cardiovascular system is tightly controlled. Mice deficient in TGF-ß1 die in utero because of vascular defects.5 Smad1-deficient mice fail to establish chorion–allantoic circulation, whereas Smad5-deficient embryos have defects in yolk sac vasculature with enlarged blood vessels.6,7 Mice deficient in the accessory receptor endoglin exhibit embryonic lethality, with cardiovascular and angiogenesis defects associated with abnormal vascular smooth muscle cell development.8 Smad6-deficient mice develop aortic ossification and elevated blood pressure.9

TGF-ß is highly expressed in injured arteries, and TGF-ß–dependent effects play a role in the pathogenesis of atherosclerosis, coronary artery disease, transplant arteriosclerosis, hypertension, diabetes, myocardial remodeling, and restenosis.10–14 Blood vessels overexpressing TGF-ß develop neointimal formation,15 whereas inhibition of TGF-ß signaling leads to the reversion of negative remodeling associated with an increase of TGF-ß.16,17 However, the effects of TGF-ß are complex and cell-type specific. For example, the role of TGF-ß in atherosclerosis is not yet fully elucidated, although it seems to regulate the equilibrium between inflammatory and fibrotic processes.18,19 TGF-ß can also induce arteriogenesis and markedly influences angiogenic processes, possessing both pro- and antiangiogenic effects.20

The reduction of NO bioavailability associated with endothelial dysfunction is strongly correlated with cardiovascular diseases including atherosclerosis.21 Thus, we decided to test the impact of endothelial-derived NO on TGF-ß–dependent gene expression in the vascular endothelium.


*    Materials and Methods
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up arrowAbstract
up arrowIntroduction
*Materials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Materials
Recombinant human TGF-ß1 was from R&D Systems (Oxon, UK). Spermine-NONOate and DEA-NONOate were from Alexis (San Diego, Calif). For other chemicals, see the expanded Materials and Methods section in the online data supplement available at http://circres.ahajournals.org.

Plasmids
Flag-tagged cGMP-dependent protein kinase 1{alpha} regulatory region (fcGK-1{alpha}R) and Flag-tagged cGMP-dependent protein kinase 1{alpha} catalytic region (fcGK-1{alpha}C) were kindly donated by Dr D. Browning (Medical College of Georgia, Augusta).22 3TP-Lux plasmid that encodes 3 tandem copies of TPA-response element plus the TGF-ß–responsive region of the PAI-1 gene cloned in front of a luciferase gene was a kind gift from Dr R. Harland (University of California, Berkeley).23 The plasmid containing SV40-driven Renilla luciferase gene was from Promega (Madison, Wis).

Cell Culture
Bovine aortic endothelial cells (BAEC) and human umbilical endothelial cells (HuVEC) were isolated as described.24

Murine aortic endothelial cells (MAEC) were cultured from endothelial NO synthase (eNOS) wild-type (WT) and eNOS-deficient mouse aortas as described25 (see also expanded Material and Methods section in the online data supplement).

RNA Isolation and Northern Blot Analysis
Total RNA from BAEC was isolated as described.26 For Northern analysis, a 274-bp fragment of human TGF-ß1, a 1600-bp fragment of collagen type I cDNA, and an 18S RNA probe were radiolabeled (Redi Prime, Amersham Pharmacia Biotech, Buckinghamshire, UK).

Immunoblotting
Immunoblotting was performed as described.26

Immunohistochemistry, Immunofluorescence, and Confocal Microscopy
Immunohistochemistry from eNOS WT and eNOS-deficient mouse aortas was performed as described25 (see also the expanded Materials and Methods section in the online data supplement).

Transient Transfection
Transfection was performed with Lipofectamine as described.26 Luciferase activity was determined using the Dual luciferase reporter kit (Promega). To determine transfection efficiency, cells were transfected with either pGL2-Control Vector containing an SV40 promoter and enhancer or a ß-galactosidase–encoding plasmid.

For cGMP-dependent protein kinase I{alpha} constructs (fcGK-I{alpha}C and fcGK I{alpha}R) overexpressing 2 µg of plasmid DNA were transiently transfected with Lipofectamine as described26 (see also the expanded Material and Methods section in the online data supplement).

Nuclear Extract Preparation and Electrophoretic Mobility-Shift Assay
Nuclear and cytosolic extracts were prepared as described27 (see also the expanded Material and Methods section in the online data supplement).

Smad Steady-State Protein Level Assays
For Smad2 stability assays, transiently transfected BAEC with Flag-tagged Smad2 were labeled for 2 hours with 50 µCi/mL [35S]methionine (Trans [35S]-label; ICN, Barcelona, Spain) and chased in the presence or absence of 30 µmol/L MG-132 for the indicated time periods. Cells were lysed and the extracts were immunoprecipitated with anti-FLAG M2-agarose affinity gel. The precipitates were electrophoresed and autoradiographed. Band intensities were quantified by densitometry.

Ubiquitination Assays
BAEC were transiently transfected with Flag-tagged Smad2 alone or Flag-Smad2 plus His-tagged ubiquitin kindly provided by Dr D. Bohmann (European Molecular Biology Laboratory, Heidelberg, Germany). Forty-eight hours after transfection, cells were lysed and F-Smad2 was immunoprecipitated with anti–Flag-M2 antibody or anti-histidine antibody; after 4 washes with lysis buffer, the immunocomplexes were resolved by SDS-PAGE and immunoblotted with anti-Flag or anti-ubiquitin.

Statistical Analysis
Experiments were performed at least 3 times, and every condition was performed in duplicate. Comparisons were made by ANOVA and Newman–Keuls post hoc testing. Results are expressed as mean±SEM, with P<0.05 considered statistically significant.


*    Results
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up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
*Results
down arrowDiscussion
down arrowReferences
 
NO Inhibits TGF-ß–Dependent Gene Transactivation Through the cGMP/PKG Pathway
We determined whether NO could affect the ability of TGF-ß to regulate gene expression in BAEC. The NO donor, Sp-NONOate (10–5 mol/L), significantly blocked the TGF-ß–mediated upregulation of TGF-ß1 and collagen type I mRNAs in a dose-dependent manner (Figure 1A). Similar results were obtained with TGF-ß–mediated fibronectin expression (data not shown). We also determined whether exogenous NO affects the activity of TGF-ß–responsive promoters. BAEC were cotransfected with a TGF-ß–sensitive promoter (3TP-Lux) and cytomegalovirus-Renilla as a control and treated with Sp-NONOate (NO) and TGF-ß as above. NO inhibited 3TP-Lux promoter activity induced by TGF-ß in a dose-dependent matter (Figure 1B). In addition, 3TP-Lux promoter activity in HuVEC stimulated with TGF-ß (8x10–4 to 8x10–1 nmol/L) resembled the typical U-shaped profile displayed for other TGF-ß–regulated effects.28 NO was able to inhibit the effects of higher concentrations of TGF-ß, whereas it boosted the response at lower TGF-ß concentrations (Figure 1C).



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Figure 1. NO inhibits TGF-ß–dependent gene expression. A, mRNA expression of TGF-ß1, collagen type I (Col. I), and 18S from BAEC treated with vehicle (CT), 0.08 nmol/L TGF-ß (TGF), 10–5 mol/L Sp-NONOate (NO), or 10–7 to 10–5 mol/L Sp-NONOate+TGF-ß (TGF+NO) for 24 hours. Right, Densitometric analysis expressed as fold increase of control (CT). *P<0.05 vs CT, **P<0.05 vs TGF (n=3). B, Luciferase activity of BAEC transfected with 3TP-Lux plasmid and treated as above. Graph represents fold induction of CT. *P<0.05 vs CT, NO alone, and the higher NO concentrations (10–6 to 10–7 mol/L)+TGF; **P<0.05 vs TGF and NO (10–7 mmol/L)+TGF (n=4). C, HuVEC were transfected as above and treated with or without NO (10–5 mol/L) plus TGF-ß at different concentrations (0 to 8x10–1 nmol/L). *P<0.05 vs TGF-ß (n=3).

Next, BAEC were treated with 8-Br-cGMP (a soluble analogue of cGMP) or Rp-8-GMPS (an antagonist of PKG-1), and TGF-ß1 mRNA expression was analyzed by Northern blot. We found that both NO and 8-Br-cGMP inhibited TGF-ß–dependent TGF-ß1 mRNA expression (Figure 2A), and the inhibitory effect of NO was reversed by Rp-8-GMPS (10–6 mol/L), suggesting that the effects of NO on TGF-ß–dependent gene expression are mediated by the soluble guanylate cyclase/cGMP pathway. Indeed, overexpression of the regulatory region of PKG-1{alpha} (fcGK-I{alpha}R), which acts as a dominant negative for PKG-1{alpha} activity, led to the abrogation of NO effects on TGF-ß–stimulated 3TP-Lux transcriptional activation (Figure 2B). Transfection with a dominant-positive construct (the catalytic region of PKG-1{alpha} that retains kinase activity in the absence of cGMP; fcGK-I{alpha}C) reproduced the effects of NO on TGF-ß–stimulated 3TP-Lux activity (Figure 2B). Transfection efficiency was verified by immunological detection with anti-Flag antibody (supplemental Figure I).



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Figure 2. NO inhibits TGF-ß–regulated gene expression through the cGMP/PKG pathway. A, mRNA detection of TGF-ß1 and 18S of BAEC incubated for 24 hours with 0.08 nmol/L TGF-ß (TGF), 10–5 mol/L Sp-NONOate (NO), 10–5 mol/L 8-Br-cGMP (8-Br-cGMP), 10–6 mol/L Rp-GMPS (Rp-GMPS), and their combinations as indicated. Top, Densitometric analysis expressed as fold induction. *P<0.05 vs CT, **P<0.05 vs TGF, #P<0.05 vs TGF+NO (n=3). B, Luciferase activity of BAEC transfected with 3TP-Lux and control plasmid (pcDNA 3.1), dominant-negative PKG-1{alpha} (fcGK-1{alpha}R), or catalytic region of PKG-1{alpha} (fcGK-1{alpha}C) and treated with vehicle (CT), 0.08 nmol/L TGF-ß (TGF), 10–5 mol/L Sp-NONOate (NO), or TGF+NO (TGF/NO). *P<0.05 vs CT and NO, +P<0.05 vs TGF (n=4).

Taken together, these results indicate that NO is able to inhibit the transactivation of TGF-ß–regulated genes through the cGMP/PKG pathway.

NO Inhibits Smad Nuclear Accumulation via PKG-1{alpha} Activation
Most of TGF-ß transcriptional responses depend on Smad phosphorylation and translocation to the nucleus. We found that TGF-ß stimulation induced Smad2/3 nuclear translocation at 15 minutes of treatment, reaching a maximum at 30 minutes, and stayed elevated for at least 2 hours. By contrast, in NO-treated cells, Smad2/3 was detectable in the nuclear fraction 90 minutes after TGF-ß stimulation (Figure 3A). To confirm the effect of NO on Smad2/3 phosphorylation and subsequent nuclear translocation, we detected phosphorylated Smad2 (red) and total Smad2/3 (green) by confocal microscopy. TGF-ß induced early Smad2 phosphorylation at 15 minutes, followed by massive migration of total Smad2/3 to the nucleus, returning to basal levels 4 hours after stimulation (Figure 3B). Pretreatment of cells with NO reduced and significantly delayed the nuclear presence of phosphorylated Smad2/3 when compared with TGF-ß alone (60 minutes versus 15 minutes), and the levels of activated Smad2 were never comparable to TGF-ß–stimulated cells alone. These results suggest that NO influences the activation of Smad2/3 on TGF-ß stimulation, reducing and delaying Smad2/3 nuclear accumulation.



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Figure 3. NO inhibits Smad2/3 nuclear accumulation and DNA binding. A, Smad2/3 expression in cytosolic and nuclear extracts of BAEC treated with 0.08 nmol/L TGF-ß or 10–5 mol/L Sp-NONOate plus TGF-ß (TGF-ß+NO) for the indicated times. For control purposes, poly(ADP-ribose) polymerase (PARP) and ß-tubulin were also detected. The graph represents nuclear Smad2/3 signal values relative to time point 0 minutes. {circ}, TGF-ß {bullet}, TGF-ß+NO. *P<0.05 vs TGF+NO (n=3). B, Detection of Smad2/3 (fluorescein isothiocyanate, green) and phospho-Smad2 (Alexa J43, red) by confocal microscopy in BAEC pretreated for 1 hour with NO or vehicle and then stimulated with TGF-ß for the indicated times (n=3). C, Electrophoretic mobility-shift assay analysis of nuclear extracts from BAEC treated with TGF-ß or TGF-ß+NO for 30 minutes, with radiolabeled SBE probe and cold SBE competitor (Comp). An antibody to Smad2 or Smad 2/3 or a nonspecific IgG was added to some binding reactions. Arrow designates supershift. Results are representative of 3 different experiments.

We also investigated the effect of NO in the DNA binding of Smad2/3 to a Smad-binding element (SBE), finding TGF-ß–inducible, NO-sensitive binding activity to DNA in the nuclear fraction of treated cells (Figure 3C). The identity of the proteins binding to the SBE was revealed by supershift analysis using specific anti-Smad2 and anti–Smad2/3 antibodies. Antibody to Smad2/3 inhibited the protein binding to DNA, whereas addition of anti-Smad2 slightly supershifted the DNA–protein complex from TGF-ß–treated cells, indicating that Smad2 forms part of the protein complex binding to the SBE.

In addition, we found that transfection with a dominant-negative PKG-1{alpha} (fcGK-1{alpha}R) reversed the NO effect on TGF-ß–induced Smad2/3 nuclear translocation, whereas transfection with a dominant-positive PKG-1{alpha} mimicked the NO effects, as detected by immunofluorescence (Figure 4A). The reduction of nuclear phospho-Smad2 levels observed in NO+TGF-ß–treated cells was reversed by preincubation with the PKG-1 inhibitor Rp-8-GMPS, as revealed by immunoblot (Figure 4B).



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Figure 4. NO effects on Smad2/3 nuclear translocation depend on PKG-1. A, Smad2/3 detection in BAEC transfected with control plasmid (pcDNA), constitutively active PKG-1{alpha} (fcGK-1{alpha}C), or dominant-negative PKG-1{alpha} (fcGK-1{alpha}R) for 24 hours, incubated with 10–5 mol/L Sp-NONOate (NO) for 1 hour, and then treated for 45 minutes with 0.08 nmol/L TGF-ß (TGF) (n=3). B, Immunoblot detection of Smad2/3, phospho-Smad2, poly(ADP-ribose) polymerase (PARP), and ß-tubulin in BAEC treated with vehicle (CT), 10–5 mol/L Sp-NONOate (NO) for 1 hour, and then treated for 30 minutes with 0.08 nmol/L TGF-ß (TGF) in the presence or the absence of 10– 6 mol/L Rp-GMPS. Right, Densitometric analysis expressed as fold increase. Smad2 phosphorylation in the absence of Rp-GMPS (white bars) or in the presence of Rp-GMPS (gray bars) is represented. *P<0.05 vs CT and NO, **P<0.05 vs TGF, +P<0.05 vs TGF+NO in the absence of Rp-GMPS (n=3).

Endogenous Endothelial NO Controls the Transcriptional Responses to TGF-ß
We found in BAEC that NO deprivation (24 hours of incubation with NG-nitro-L-arginine methyl ester [L-NAME] at different concentrations) exacerbates TGF-ß–induced Smad2 phosphorylation (Figure 5A). On the other hand, bradykinin stimulation of eNOS reproduced the effect of NO on TGF-ß–induced Smad2 phosphorylation (Figure 5B). In addition, TGF-ß1 mRNA expression was also enhanced by NO deprivation, indicating that endogenous endothelial NO has a role in TGF-ß–elicited gene expression (Figure 5C).



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Figure 5. Endothelial NO is a physiological modulator of TGF-ß/Smad signaling in BAEC. A, Immunoblot detection of Smad2/3 and P-Smad2 from cell lysates of BAEC treated with L-NAME at the indicated concentrations for 24 hours and stimulated for 30 minutes with 0.08 nmol/L TGF-ß (TGF). Bottom, Densitometric analysis of P-Smad2/ Smad2/3 ratio, expressed as arbitrary units. *P<0.05 vs CT, **P<0.05 vs TGF (n=3). B, With or without 10–5 mol/L DEA-NONOate or 10–6 mol/L bradykinin (BrK) for 30 minutes and stimulated with 0.08 nmol/L TGF-ß (TGF) for 30 minutes. Bottom, Densitometric analysis of P-Smad2:Smad2/3 ratio, expressed as arbitrary units. *P<0.05 vs CT, **P<0.05 vs TGF (n=3). C, mRNA expressions of TGF-ß1 and 18S (control) from BAEC treated with L-NAME at the indicated concentrations and stimulated with 0.08 nmol/L TGF-ß (TGF) for 24 hours. Bottom, Densitometric analysis expressed as fold of induction. *P<0.05 vs CT (n=3).

To investigate the physiological relevance of those results, aortic rings from WT and eNOS-deficient (KO) mice were used to test basal TGF-ß1 and collagen type I expression by immunohistochemistry. TGF-ß1 expression was found to be higher in eNOS KO aortas (Figure 6A). Collagen type I content was also increased in the eNOS KO aortas. To quantify these results, aortas were collected and TGF-ß1 and collagen type I expression were analyzed by immunoblot. Figure 6B shows that TGF-ß1 and collagen type I protein expression was significantly higher in eNOS KO aortas than in WT, indicating that NO regulates TGF-ß–dependent gene expression in vivo.



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Figure 6. Endothelial NO is a physiological modulator of TGF-ß/Smad signaling in vivo. A, Immunohistochemical detection of TGF-ß1 (left) or collagen type I (right) in aortic rings from eNOS WT or eNOS-deficient mice (KO). Top panels, x20 magnification. Bottom panels, x60 magnification. Results are representative of 8 different experiments. B, left, Immunoblot detection of TGF-ß1 and collagen type I (Col. I) expression in aortic rings from WT and eNOS-deficient mice (KO). eNOS and ß-tubulin expression were used as controls. Right, Densitometric analysis of TGF-ß1/ß-tubulin (gray bars) or collagen type I/ß-tubulin (black bars) ratio, expressed as arbitrary units. *P<0.05 vs WT (n=6 with 3 aortas pooled for each condition). C, Confocal microscopy detection of Smad2/3 (green) and phospho-Smad2 (red) in MAEC from eNOS WT or eNOS-deficient (KO) mice, preincubated for 1 hour with 10–6 mol/L DEA-NONOate (NO) and stimulated with 0.08 nmol/L TGF-ß (TGF) for 30 minutes (n=4). D, Luciferase activity measurement for 24 hours after transfection of MAEC from eNOS WT or eNOS-deficient (KO) mice, with 3TP-Lux and stimulated with 0 to 8x10–1 nmol/L TGF-ß (n=6). *P<0.05 vs eNOS WT MAEC.

To further explore the role of endogenous NO, we studied TGF-ß–stimulated Smad2 phosphorylation in MAEC from eNOS KO and WT animals by confocal microscopy. TGF-ß enhanced Smad2 phosphorylation in MAEC from eNOS-deficient mice (Figure 6C). Preincubation with 10–5 mol/L DEA-NONOate (NO) produced a strong inhibition of Smad2 phosphorylation in both WT and KO endothelial cells, being more pronounced in the latter. In addition, the transcriptional response to TGF-ß was also higher in MAEC from eNOS KO mice at the different TGF-ß concentrations assayed (Figure 6D).

Taken together, these results confirm the role of endothelial NO in the regulation of the transcriptional responses to TGF-ß in the vascular endothelium.

NO Accelerates the Degradation of Smad2/3 by the Proteasome
TGF-ß–mediated Smad2/3 activation can be negatively regulated by the overexpression of I-Smads (Smads 6 and 7).4,29 To exclude this possibility, BAEC were incubated with TGF-ß or TGF-ß+Sp-NONOate (NO) for 0 to 4 hours, and Smad6 or Smad7 levels were evaluated by immunoblot; we found no differences on Smad6 or Smad7 levels (Figure 7A). A longer time-course experiment, up to 24 hours, was performed with identical results (supplemental Figure II).



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Figure 7. Proteasome inhibitors reversed the effect of NO on activated Smad2. A, Immunoblot detection of Smad6, Smad7, and ß-tubulin (control) in cell lysates of BAEC pretreated for 1 hour with 10–5 mol/L Sp-NONOate (NO) or vehicle and stimulated with 0.08 nmol/L TGF-ß (TGF) for the indicated times (n=3). B, Immunoblot detection of Smad2/3 and P-Smad2 from cell lysates of BAEC treated with vehicle, TGF, or NO for 30 minutes and preincubated 30 minutes in the presence or the absence of the proteasome inhibitors MG-132 (10–6 mol/L) (MG) or PI-II (10–6 mol/L). Top, Densitometric analysis (n=3). Values were represented as fold induction with respect to control. *P<0.05 vs CT.

TGF receptor activation leads to Smad2 degradation by the proteasome pathway.30To address whether Smad2 degradation was the underlying mechanism of NO, the level of phosphorylated Smad2 to total Smad2/3 in response to TGF-ß was evaluated by immunoblot. Cell preincubation with proteasome inhibitors (MG-132 and proteasome inhibitor II [PI-II]) produced a reversion of the inhibitory effect of NO on TGF-ß–mediated Smad2 phosphorylation (Figure 7B), suggesting that the proteasome pathway plays a role in NO effects.

We measured the metabolic stability of a ectopically expressed Flag-tagged Smad2 (Flag-Smad2). TGF-ß treatment reduced Flag-Smad2 stability, and the effect was reversed by pretreatment with the proteasome inhibitor MG-132 (Figure 8A). In addition, we found that NO alone had a slight effect in the stability of Smad2. However, the effect was dramatic on Flag-Smad2 protein stability induced by TGF-ß, suggesting that NO effects are mediated by a decrease in Smad2 metabolic stability.



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Figure 8. NO enhances proteasome-dependent degradation of Smad2 through the ubiquitin pathway. A, Flag-Smad2 detection by pulse-chase metabolic labeling in transfected BAEC treated with vehicle, 0.08 nmol/L TGF-ß (TGF), 10–5 mol/L Sp-NONOate (NO), or TGF-ß+NO in the absence or the presence of 10–5 mol/L MG-132 (MG-132) for 4 hours and chased for the indicated time periods. The graph represents Flag-Smad2 signal values relatives to chasing time point 0 hour (n=3). B, Ubiquitination of transfected Flag-Smad2 was detected by immunoprecipitation (IP) in BAEC treated with vehicle (CT), TGF, or TGF+NO for 4 hours in the presence or absence of 10–5 mol/L MG-132 (n=3). C, BAEC were transfected with Flag-Smad2 or His-tagged ubiquitin (His-Ub) or both and treated with TGF-ß1 with or without NO as above. Cell lysates were immunoprecipitated with anti-His antibodies. Flag-Smad2 and multiubiquitinated Smad2 were visualized by immunoblot (IB) (n=3).

Next, Smad2 ubiquitination mediated by NO was examined by ubiquitination assays in intact cells. The effect of TGF-ß on Flag-Smad2 ubiquitination was examined by adding TGF-ß 24 hours after transfection. The results demonstrated that TGF-ß induced the ubiquitination of Smad2, which was enhanced by MG-132 treatment (Figure 8B, lanes 2 and 5). NO treatment further promoted the ubiquitination of Flag-Smad2, and this effect was also enhanced in the presence of MG-132 (Figure 8B, lanes 3 and 6). To better characterized this effect, we repeated the ubiquitination assays for Flag-Smad2 in the presence or the absence of His-tagged ubiquitin. Immunoprecipitation was performed using anti-His antibody followed by anti-Flag immunoblot. Total Flag-Smad2 content was detected by immunoblotting of total cell lysates. Such analysis showed that TGF-ß induced the conjugation of ubiquitin molecules to Flag-Smad2, and this effect was enhanced by NO treatment (Figure 8C).


*    Discussion
up arrowTop
up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
up arrowResults
*Discussion
down arrowReferences
 
Our data suggest a new role for the NO/cGMP/PKG pathway in vascular endothelium. NO inhibits TGF-ß activation of endothelial gene expression by interfering with Smad signaling, leading to the degradation of Smad2 by the ubiquitin proteasome pathway.

Alterations in the local abundance of TGF-ß1 appear to promote vascular wall remodeling, arterial lesion growth, and vascular cell transdifferentiation. On the other hand, TGF-ß can also act as an antiinflammatory and antiatherogenic cytokine with a protective role in the complications of atherosclerosis. Different levels of interaction between the TGF-ß and NO pathways have been reported in diabetes and hypertension.31,32 TGF-ß can induce eNOS expression through the Smad pathway,26 and TGF-ß can inhibit inducible NOS by multiple mechanisms.33–35 By contrast, stimulatory effects of NO on TGF-ß production have been reported in smooth muscle cells.36 We show that endothelial cells treated with an NO donor exhibit a decreased response to TGF-ß, resulting in a downregulation of TGF-ß target genes. NO targeted the Smad pathway because NO inhibited Smad2 phosphorylation and nuclear translocation. In addition, we show that NO decreases the binding of Smad to a SBE, possibly because of the decreased Smad presence in the nucleus. Because NO can decrease the affinity of several transcription factors to DNA by S-nitrosylation,37–39 another explanation for these effects is that NO interferes with the Smad binding to SBEs.

PKG-1 inhibition reversed the inhibitory effects of NO on the TGF/Smad signaling. Moreover, overexpression of dominant-negative PKG-1{alpha} was reversed, and the expression of a dominant-positive PKG-1{alpha} mimicked the inhibitory effect of NO on Smad2 nuclear translocation. Those results corroborate our previous findings regarding PKG-1{alpha} as the main effector of the NO/cGMP pathway.40 Similarly, natriuretic peptides counteract TGF-ß actions through a cGMP/PKG pathway.41 cAMP-elevating agents also inhibit the TGF/Smad pathway through PKA activation.42 Taken together, a new role for cyclic mononucleotide phosphate second messengers in controlling growth factor responses can be suggested.

If NO controls basal TGF-ß–dependent gene expression and signaling attributable to Smad activation, a lack of NO should increase the responses to TGF-ß. Our results show that endogenous NO helps to maintain endothelial TGF-ß signaling under a tight control, both in cultured cells and in vivo. Inhibition of endogenous NO production augmented the responses to TGF-ß, whereas increased eNOS activity by bradykinin mimicked the effect of NO donors in endothelial cells. In vivo, there is a marked increase in TGF-ß1 and collagen type I expression in the aortas from eNOS-deficient mice. In MAEC, lack of eNOS exacerbated the transcriptional responses to TGF-ß and increased the overall Smad2 phosphorylation. Addition of NO decreased phospho-Smad2 levels in eNOS WT MAEC, whereas it restored phosphorylation to control levels in the eNOS-null MAEC.

Long-term inhibition of NO synthesis accelerates atherosclerosis, inducing early vascular inflammation as well as cardiac fibrosis and glomerulosclerosis.43–45 These effects had been correlated with augmented collagen deposition in arteries and hearts accompanied by an increase in TGF-ß1 expression. Indeed, mice lacking eNOS developed greater neointimal proliferation or showed diminished remodeling compared with control mice.46 By contrast, eNOS gene delivery protects against many of those manifestations, such as cardiac remodeling after myocardial infarction, TGF-ß overexpression in aortic and heart fibrosis, and luminal narrowing after coronary angioplasty.47–49 Based on this and our results, we suggest that impaired NO signal transduction may increase TGF-ß responses, which could contribute to the pathogenesis of some vascular diseases.

The ubiquitin–proteasome pathway regulates the activation status of the Smad family of proteins. Smad7 acts as an adaptor protein recruiting the E3 ligase Smurfs to the TGF-ß receptor complex, which induces its degradation.50 Endothelial cell treatment with 2 different proteasome inhibitors reversed the inhibitory effects of NO over TGF-ß/Smads. The impact of NO signaling over the proteasome pathway is starting to emerge. Our previous work indicates that C-type natriuretic peptide activates the proteolytic degradation of soluble guanylate cyclase by the proteasome through a cGMP/PKG–dependent pathway.51 Others have shown that NO increases the proteolytic activity of the 20S and 26S proteasome in endothelial cells to inhibit H2O2-induced transferrin receptor-dependent apoptosis52 and that NO can S-nitrosylate Parkin, an E3 ubiquitin ligase important in the survival of dopamine neurons in Parkinson’s disease.53 Our results clearly show that NO increased the degradation of Smad activated by TGF-ß in an ubiquitin-proteasome–dependent manner. NO reduced the metabolic life of Flag-Smad2 after TGF-ß stimulation, and NO increased the ubiquitination of Smad2 induced by TGF-ß. The exact molecular mechanism exerted by NO is still undetermined. Many of the effects described in the present report are dependent on PKG activation, and there are some reports indicating that phosphorylated proteasomes have higher activities.54 PKG might initiate a kinase cascade that could enhance the proteasomal activity, thus contributing to an accelerated Smad2 degradation.

Our results support the hypothesis that NO serves as a molecular restraint to the excessive actions of TGF-ß. It is possible that NO regulates TGF-ß–derived gene expression in the setting of pathological TGF-ß activation. Alternatively, NO may help to terminate TGF-ß signaling. Thus, specific control of TGF-ß expression and signaling by endothelial NO may be required to maintain vascular wall homeostasis.


*    Acknowledgments
 
This work was supported by Comiminunided de Madrid ("CAM") (08.4/0023/2003) (to M.S. and C.Z.); Spanish Society of Nephrology ("SEN,2003") (to M.S.); Ministerio de Ciercia y Tecnologist ("MCyT") (SAF 2002-00399) (to C.Z.); and "MCyT" (BFI 2001-1036) and "CAM" (08.4/0012/2001-2) (to M.R.-P.). M.S. and C.Z. are research investigators "Ramón y Cajal" (MCyT).


*    Footnotes
 
Original received July 7, 2004; resubmission received May 13, 2005; revised resubmission received September 29, 2005; accepted October 6, 2005.


*    References
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*References
 
1. Pintavorn P, Ballermann BJ. TGF-beta and the endothelium during immune injury. Kidney Int. 1997; 51: 1401–1412.[Medline] [Order article via Infotrieve]

2. Chabrier PE. Growth factors and vascular wall. Int Angiol. 1996; 15: 100–103.[Medline] [Order article via Infotrieve]

3. Kretzschmar M, Massague J. SMADs: mediators and regulators of TGF-beta signaling. Curr Opin Genet Dev. 1998; 8: 103–111.[CrossRef][Medline] [Order article via Infotrieve]

4. Topper JN, Cai J, Qiu Y, Anderson KR, Xu YY, Deeds JD, Feeley R, Gimeno CJ, Woolf EA, Tayber O, Mays GG, Sampson BA, Schoen FJ, Gimbrone MA Jr, Falb D. Vascular MADs: two novel MAD-related genes selectively inducible by flow in human vascular endothelium. Proc Natl Acad Sci U S A. 1997; 94: 9314–9319.[Abstract/Free Full Text]

5. Dickson MC, Martin JS, Cousins FM, Kulkarni AB, Karlsson S, Akhurst RJ. Defective haematopoiesis and vasculogenesis in transforming growth factor-beta 1 knock out mice. Development. 1995; 121: 1845–1854.[Abstract]

6. Tremblay KD, Dunn NR, Robertson EJ. Mouse embryos lacking Smad1 signals display defects in extra-embryonic tissues and germ cell formation. Development. 2001; 128: 3609–3621.[Abstract/Free Full Text]

7. Yang X, Castilla LH, Xu X, Li C, Gotay J, Weinstein M, Liu PP, Deng CX. Angiogenesis defects and mesenchymal apoptosis in mice lacking SMAD5. Development. 1999; 126: 1571–1580.[Abstract]

8. Li DY, Sorensen LK, Brooke BS, Urness LD, Davis EC, Taylor DG, Boak BB, Wendel DP. Defective angiogenesis in mice lacking endoglin. Science. 1999; 284: 1534–1537.[Abstract/Free Full Text]

9. Galvin KM, Donovan MJ, Lynch CA, Meyer RI, Paul RJ, Lorenz JN, Fairchild-Huntress V, Dixon KL, Dunmore JH, Gimbrone MA Jr, Falb D, Huszar D. A role for smad6 in development and homeostasis of the cardiovascular system. Nat Genet. 2000; 24: 171–174.[CrossRef][Medline] [Order article via Infotrieve]

10. Spriewald BM, Ensminger SM, Billing JS, Morris PJ, Wood KJ. Increased expression of transforming growth factor-beta and eosinophil infiltration is associated with the development of transplant arteriosclerosis in long-term surviving cardiac allografts. Transplantation. 2003; 76: 1105–1111.[Medline] [Order article via Infotrieve]

11. Ryan ST, Koteliansky VE, Gotwals PJ, Lindner V. Transforming growth factor-beta-dependent events in vascular remodeling following arterial injury. J Vasc Res. 2003; 40: 37–46.[CrossRef][Medline] [Order article via Infotrieve]

12. Mata-Greenwood E, Meyrick B, Steinhorn RH, Fineman JR, Black SM. Alterations in TGF-beta1 expression in lambs with increased pulmonary blood flow and pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol. 2003; 285: L209–L221.[Abstract/Free Full Text]

13. Porreca E, Di Febbo C, Mincione G, Reale M, Baccante G, Guglielmi MD, Cuccurullo F, Colletta G. Increased transforming growth factor-beta production and gene expression by peripheral blood monocytes of hypertensive patients. Hypertension. 1997; 30: 134–139.[Abstract/Free Full Text]

14. Shi Y, O’Brien JE Jr, Fard A, Zalewski A. Transforming growth factor-beta 1 expression and myofibroblast formation during arterial repair. Arterioscler Thromb Vasc Biol. 1996; 16: 1298–1305.[Abstract/Free Full Text]

15. Schulick AH, Taylor AJ, Zuo W, Qiu CB, Dong G, Woodward RN, Agah R, Roberts AB, Virmani R, Dichek DA. Overexpression of transforming growth factor beta 1 in arterial endothelium causes hyperplasia, apoptosis, and cartilaginous metaplasia. Proc Natl Acad Sci U S A. 1998; 95: 6983–6988.[Abstract/Free Full Text]

16. Kingston PA, Sinha S, David A, Castro MG, Lowenstein PR, Heagerty AM. Adenovirus-mediated gene transfer of a secreted transforming growth factor-beta type II receptor inhibits luminal loss and constrictive remodeling after coronary angioplasty and enhances adventitial collagen deposition. Circulation. 2001; 104: 2595–2601.[Abstract/Free Full Text]

17. Wolf YG, Rasmussen LM, Ruoslahti E. Antibodies against transforming growth factor-ß1 suppress intimal hyperplasia in a rat model. J Clin Invest. 1994; 93: 1172–1178.[Medline] [Order article via Infotrieve]

18. McCaffrey T. TGF-ßs and TGF-ß receptors in atherosclerosis. Cytokine Growth Factor Rev. 2000; 11: 103–114.[CrossRef][Medline] [Order article via Infotrieve]

19. Pepper MS. Transforming growth factor-ß: vasculogenesis, angiogenesis, and vessel wall integrity. Cytokine Growth Factor Rev. 1997; 8: 21–43.[CrossRef][Medline] [Order article via Infotrieve]

20. Goumans MJ, Lebrin F, Valdimarsdottir G. Controlling the angiogenic switch: a balance between two distinct TGF-ß receptor signaling pathways. Trends Cardiovasc Med. 2003; 13: 301–307.[CrossRef][Medline] [Order article via Infotrieve]

21. Li H, Wallerath T, Forstermann U. Physiological mechanisms regulating the expression of endothelial-type NO synthase. Nitric Oxide. 2002; 7: 132–147.[CrossRef][Medline] [Order article via Infotrieve]

22. Browning DD, Mc Shane M, Marty C, Ye RD. Functional analysis of type 1alpha cGMP-dependent protein kinase using green fluorescent fusion proteins. J Biol Chem. 2001; 276: 13039–13048.[Abstract/Free Full Text]

23. Carcamo J, Zentella A, Massague J. Disruption of transforming growth factor beta signaling by a mutation that prevents transphosphorylation within the receptor complex. Mol Cell Biol. 1995; 3: 1573–1581.

24. Arnet UA, McMillan A, Dinerman JL, Ballermann B, Lowenstein CJ. Regulation of endothelial nitric-oxide synthase during hypoxia. J Biol Chem. 1996; 271: 15069–15073.[Abstract/Free Full Text]

25. Lopez-Rivera E, Lizarbe TR, Martinez-Moreno M, Lopez-Novoa JM, Rodriguez-Barbero A, Rodrigo J, Fernandez AP, Alvarez-Barrientos A, Lamas S, Zaragoza C. Matrix metalloproteinase 13 mediates nitric oxide activation of endothelial cell migration. Proc Natl Acad Sci U S A. 2005; 102: 3685–3690.[Abstract/Free Full Text]

26. Saura M, Zaragoza C, Cao W, Bao C, Rodriguez-Puyol M, Rodriguez-Puyol D, Lowenstein CJ. Smad2 mediates transforming growth factor-beta induction of endothelial nitric oxide synthase expression. Circ Res. 2002; 91: 806–813.[Abstract/Free Full Text]

27. Saura MZC, Bao C, McMillan A, Lowenstein CJ. Interaction of interferon regulatory factor-1 and nuclear factor kappaB during activation of inducible nitric oxide synthase transcription. J Mol Biol. 1999; 289: 459–471.[CrossRef][Medline] [Order article via Infotrieve]

28. DiChiara MR, Kiely JM, Gimbrone MA Jr, Lee ME, Perrella MA, Topper JN. Inhibition of E-selectin gene expression by transforming growth factor beta in endothelial cells involves coactivator integration of Smad and nuclear factor kappaB-mediated signals. J Exp Med. 2000; 192: 695–704.[Abstract/Free Full Text]

29. Ulloa L, Doody J, Massagué J. Inhibition of transforming growth factor-b/SMAD signalling by the interferon-{gamma}/STAT pathway. Nature. 1999; 397: 710–713.[CrossRef][Medline] [Order article via Infotrieve]

30. Lo RS, Massague J. Ubiquitin-dependent degradation of TGF-beta-activated smad2. Nat Cell Biol. 1999; 1: 472–478.[CrossRef][Medline] [Order article via Infotrieve]

31. Ying WZ, Sanders PW. The interrelationship between TGF-beta1 and nitric oxide is altered in salt-sensitive hypertension. Am J Physiol Renal Physiol. 2003; 285: F902–F908.[Abstract/Free Full Text]

32. Wang SWX, Lincoln TM, Murphy-Ullrich JE. Expression of constitutively active cGMP-dependent protein kinase prevents glucose stimulation of thrombospondin 1 expression and TGF-beta activity. Diabetes. 2003; 52: 2144–2150.[Abstract/Free Full Text]

33. Vodovotz Y. Control of nitric oxide production by transforming growth factor-beta1: mechanistic insights and potential relevance to human disease. Nitric Oxide. 1997; 1: 3–17.[CrossRef][Medline] [Order article via Infotrieve]

34. Kunz D, Walker G, Pfeilschifter J. Transforming growth factor-beta 2 inhibits interleukin 1 beta-induced expression of inducible nitric oxide synthase in rat renal mesangial cells. Inflamm Res. 1997; 46: 327–331.[CrossRef][Medline] [Order article via Infotrieve]

35. Vodovotz Y, Geiser AG, Chesler L, Letterio JJ, Campbell A, Lucia MS, Sporn MB, Roberts AB. Spontaneously increased production of nitric oxide and aberrant expression of the inducible nitric oxide synthase in vivo in the transforming growth factor beta 1 null mouse. J Exp Med. 1996; 183: 2337–2342.[Abstract/Free Full Text]

36. Schmidt A, Geigenmueller S, Voelker W, Seiler P, Buddecke E. Exogenous nitric oxide causes overexpression of TGF-beta1 and overproduction of extracellular matrix in human coronary smooth muscle cells. Cardiovasc Res. 2003; 58: 671–678.[Abstract/Free Full Text]

37. Marshall HE, Stamler JS. Inhibition of NF-kappa B by S-nitrosylation. Biochemistry. 2001; 40: 1688–1693.[CrossRef][Medline] [Order article via Infotrieve]

38. Pineda-Molina E, Lamas S. Nitric oxide as a regulator of gene expression: studies with the transcription factor proteins cJun and p50. Biofactors. 2001; 15: 113–115.[Medline] [Order article via Infotrieve]

39. So HS, Park RK, Kim MS, Lee SR, Jung BH, Chung SY, Jun CD, Chung HT. Nitric oxide inhibits c-Jun N-terminal kinase 2 (JNK2) via S-nitrosylation. Biochem Biophys Res Commun. 1998; 247: 809–813.[CrossRef][Medline] [Order article via Infotrieve]

40. Rivero-Vilches FJ, de Frutos S, Saura M, Rodriguez-Puyol D, Rodriguez-Puyol M. Differential relaxing responses to particulate or soluble guanylyl cyclase activation on endothelial cells: a mechanism dependent on PKG-1 alpha activation by NO/cGMP. Am J Physiol Cell Physiol. 2003; 285: C891–C898.[Abstract/Free Full Text]

41. Kapoun AM, Liang F, O’Young G, Damm DL, Quon D, White RT, Munson K, Lam A, Schreiner GF, Protter AA. B-type natriuretic peptide exerts broad functional opposition to transforming growth factor-beta in primary human cardiac fibroblasts: fibrosis, myofibroblast conversion, proliferation, and inflammation. Circ Res. 2004; 94: 453–461.[Abstract/Free Full Text]

42. Schiller M, Verrecchia F, Mauviel A. Cyclic adenosine 3',5'-monophosphate-elevating agents inhibit transforming growth factor-beta-induced SMAD3/4-dependent transcription via a protein kinase A-dependent mechanism. Oncogene. 2003; 22: 8881–8890.[CrossRef][Medline] [Order article via Infotrieve]

43. Goto D, Fujii S, Zaman AK, Sakuma I, Gao M, Koyama T, Mitchell J, Woodcock-Mitchell J, Sobel BE, Kitabatake A. Long-term blockade of nitric oxide synthesis in rats modulates coronary capillary network remodeling. Angiogenesis. 1999; 3: 137–146.[CrossRef][Medline] [Order article via Infotrieve]

44. Kataoka C, Egashira K, Inoue S, Takemoto M, Ni W, Koyanagi M, Kitamoto S, Usui M, Kaibuchi K, Shimokawa H, Takeshita A. Important role of Rho-kinase in the pathogenesis of cardiovascular inflammation and remodeling induced by long-term blockade of nitric oxide synthesis in rats. Hypertension. 2002; 39: 245–250.[Abstract/Free Full Text]

45. Ono H, Saitoh M, Ono Y, Ishimitu T. Matsuoka Imidapril improves L-NAME-exacerbated nephrosclerosis with TGF-beta 1 inhibition in spontaneously hypertensive rats. J Hypertens. 2004; 22: 1389–1395.[CrossRef][Medline] [Order article via Infotrieve]

46. Huang PL Lessons learned from nitric oxide synthase knockout animals. Semin Perinatol. 2000; 24: 87–90.[CrossRef][Medline] [Order article via Infotrieve]

47. Iwata A, Sai S, Moore M, Nyhuis J, de Fries-Hallstrand R, Quetingco GC, Allen MD. Gene therapy of transplant arteriopathy by liposome-mediated transfection of endothelial nitric oxide synthase. J Heart Lung Transplant. 2000; 19: 1017–1028.[CrossRef][Medline] [Order article via Infotrieve]

48. Varenne O, Pislaru S, Gillijns H, Van Pelt N, Gerard RD, Zoldhelyi P, Van de Werf F. Local adenovirus-mediated transfer of human endothelial nitric oxide synthase reduces luminal narrowing after coronary angioplasty in pigs. Circulation. 1998; 98: 919–926.[Abstract/Free Full Text]

49. Smith RS Jr, Agata J, Xia CF, Chao L, Chao J. Human endothelial nitric oxide synthase gene delivery protects against cardiac remodeling and reduces oxidative stress after myocardial infarction. Life Sci. 2005; 76: 2457–2471.[CrossRef][Medline] [Order article via Infotrieve]

50. Wang T. The 26S proteasome system in the signaling pathways of TGF-beta superfamily. Front Biosci. 2003; 8: 1109–1127.[CrossRef]

51. de Frutos S, Saura M, Rivero-Vilches FJ, Rodriguez-Puyol D, Rodriguez-Puyol M. C-type natriuretic peptide decreases soluble guanylate cyclase levels by activating the proteasome pathway. Biochim Biophys Acta. 2003; 1643: 105–112.[Medline] [Order article via Infotrieve]

52. Kotamraju S, Tampo Y, Keszler A, Chitambar CR, Joseph J, Haas AL, Kalyanaraman B. Nitric oxide inhibits H2O2-induced transferrin receptor-dependent apoptosis in endothelial cells: role of ubiquitin-proteasome pathway. Proc Natl Acad Sci U S A. 2003; 100: 10653–10658.[Abstract/Free Full Text]

53. Chung KK, Thomas B, Li X, Pletnikova O, Troncoso JC, Marsh L, Dawson VL, Dawson TM. S-nitrosylation of parkin regulates ubiquitination and compromises parkin’s protective function. Science. 2004; 304: 1328–1331.[Abstract/Free Full Text]

54. Bose S, Mason GG, Rivett AJ. Phosphorylation of proteasomes in mammalian cells. Mol Biol Rep. 1999; 26: 11–14.[CrossRef][Medline] [Order article via Infotrieve]


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