Skip Navigation

Cardiovascular Research 2006 69(2):520-526; doi:10.1016/j.cardiores.2005.10.014
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Kim, C. S.
Right arrow Articles by Jeon, B. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kim, C. S.
Right arrow Articles by Jeon, B. H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Copyright © 2005, European Society of Cardiology

Apurinic/apyrimidinic endonuclease1/redox factor-1 inhibits monocyte adhesion in endothelial cells

Cuk Seong Kima, Sook Jin Sona, Eun Kyung Kima, Seon Nyo Kima, Dae Goon Yooa, Hyo Shin Kima, Sung Woo Ryooa, Sang Do Leea, Kaikobad Iranib and Byeong Hwa Jeona,*

aDepartment of Physiology, College of Medicine, Chungnam National University, 6 Munhwa-dong, Jung-gu, Daejeon, 301-131 Korea
bCardiovascular Institute, University of Pittsburgh Medical Center, Pittsburgh USA

* Corresponding author. Tel.: +82 42 580 8214; fax: +82 42 585-8440. Email address: bhjeon{at}cnu.ac.kr

Received 8 July 2005; revised 14 October 2005; accepted 18 October 2005


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 
Objective: Expression of adhesion molecules on endothelial cells and subsequent monocyte adhesion are initial events in the development of atherosclerosis. The purpose of this study was to investigate the role of apurinic/apyrmidinic endonuclease1/redox factor-1 (APE1/ref-1) in the interaction of monocytes with vascular endothelial cells.

Methods: Human umbilical vein endothelial cells (HUVECs) were transfected with an adenovirus encoding human APE1/ref-1. The effect of APE1/ref-1 overexpression on monocyte adhesion, vascular cell adhesion molecule-1 (VCAM-1) protein expression, and intracellular superoxide production in tumor necrosis factor (TNF)-{alpha}-activated HUVECs was examined.

Results: Adhesion of the monocytic cell line U937 to TNF-{alpha}-stimulated HUVECs in which APE1/ref-1 was overexpressed was suppressed. APE1/ref-1 overexpression also suppressed expression of VCAM-1 induced by TNF-{alpha}. APE1/ref-1-mediated suppression of VCAM-1 was blocked by pretreatment with the nitric oxide synthase (NOS) inhibitor L-nitroarginine methyl ester. Furthermore, APE1/ref-1 overexpression inhibited the TNF-{alpha}-induced increase in intracellular superoxide and p38 MAPK phosphorylation.

Conclusions: These data provide evidence that APE1/ref-1 in endothelial cells mitigates TNF-{alpha}-induced monocyte adhesion and expression of vascular cell adhesion molecules, and this anti-adhesive property of APE1/ref-1 is primarily mediated by a NOS-dependent mechanism. Furthermore, APE1/ref-1 may inhibit VCAM-1 expression by inhibiting superoxide production and p38 MAPK activation.

KEYWORDS Apurinic/apyrimidinic endonuclease1/redox factor-1; Monocyte adhesion; Endothelial cells; VCAM-1; p38 MAPK


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 References
 
The development of an atherosclerotic lesion requires a complex interplay between mononuclear cells, endothelia, vascular smooth muscle cells, growth factors, and cytokines. Monocyte rolling and adhesion to the vascular endothelial lining and subsequent diapedesis are not only the first steps, but also seem to be crucial events in the pathological process [1]. Expression of cell adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), on endothelial cells represents one of earliest pathological changes in inflammatory diseases, such as atherosclerosis [2]. As the phenotype of endothelial cells is subject to change by oxidative stress, reactive oxygen species (ROS), such as superoxide ions, are implicated in the pathogenesis of cardiovascular disorders [3].

Among the endogenous mechanisms that repair oxidative DNA damage is the ubiquitously expressed apurinic/apyrimidinic endonuclease1/redox factor-1 (APE1/ref-1), APE1/ref-1 is a protein with dual function [4]. It is an essential endonuclease in the base excision repair pathway of oxidatively damaged DNA, as well as having reducing properties that promote the binding of redox-sensitive transcription factors such as activator protein-1 to their cognate DNA sequences [5,6].

In addition to its nuclear functions, an extra-nuclear role for APE1/ref-1 in the regulation of endothelial oxidative stress has been uncovered. APE1/ref-1 suppresses oxidative stress through modulation of cytoplasmic rac1-regulated ROS generation [7,8]. This action of APE1/ref-1 and its reported effect on endothelial nitric oxide (NO) levels [9], suggests a possible protective role for APE1/ref-1 in inflammatory vascular disorders.

Vascular APE1/ref-1 is upregulated in atherosclerosis and animal models of hypertension [10]. However, the functional role of APE1/ref-1 in the early pathogenesis of inflammatory vascular disorders such as atherosclerosis is not known. We hypothesized that APE1/ref-1 expression serves to suppress endothelial cell adhesion molecule expression and consequent monocyte adhesion to the endothelium.


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 References
 
2.1 Cell culture and reagent
Human umbilical vein endothelial cells (HUVECs) were purchased from Clonetics (Cambrex Bio Science, MD, USA) and were grown and maintained in endothelial growth medium. Cells were used between passages 3 and 6. U937 cell lines were obtained from American type culture collection (Manassas, VA, USA). Anti-VCAM-1 and anti-APE1/ref-1 were from Santa Cruz Biotechnology (Santa Cruz, CA, USA). Anti-phospho-p38, anti-phopho-eNOS, and anti-p38 were from Cell Signaling technology (Beverly, MA, USA). Anti-Cu/Zn SOD and anti-Mn SOD were from Stressgen (Victoria, BC Canada). HRP-labeled anti-rabbit and anti-mouse antibodies were from Amersham (Buckinghamshire, UK). Human TNF-{alpha}, L-nitroarginine methyl ester, dihydroethidine were purchased from Sigma (St. Louis, MO, USA).

2.2 Western blot analysis
Twenty-four to 48 h after infection with adenoviruses, expression and phosphorylation of proteins (50 µg) was determined by Western blotting as described previously [9]. Immunoreactivity was detected with an enhanced chemiluminescence (ECL) kit (Amersham Pharmacia Biotech).

2.3 Adenoviral transfections
Adenoviruses encoding β-galactosidase (Adβgal), full-length APE1/ref-1 (AdAPE1/ref-1), were generated by homologous recombination in human embryonic kidney 293 cells, and have been described previously [9]. HUVECs were infected with 200 multiplicity of infection (MOI; particle forming units per cell) of specified adenovirus for 18 h. The virus was removed and cells incubated for another 24 h.

2.4 Detection of superoxide production
Intracellular superoxide was detected by using the superoxide-sensitive fluorophore dihydroethidine (DHE). For detection of DHE fluorescence, cells were grown in chamber slides (2 x 105 cells/well) (Nalgen Nunc International). Cells were rinsed three times with 3 ml of Krebs–HEPES buffer and then incubated in 10 µM DHE for 20 min at 37 °C in Krebs–HEPES buffer. DHE was then washed from the cells to avoid absorption of any extracellular oxyethidium formed by autooxidation of DHE, and cells were imaged using a confocal microscope.

2.5 Monocyte-endothelial cell adhesion assay
U937 cells were fluorescently labeled with 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxy-fluorescein acetoxymethyl ester (BCECF-AM) for the quantitative adhesion assay. The U937 cells were fluorescently labeled by incubating the cells (1 x 107 cells/ml) with 1 µM BCECF-AM in RPMI-1640 medium for 30 min at 37 °C and 5% CO2. HUVECs were seeded in 24-well plates to reach confluent monolayers and incubated with Adβgal (as a control) or AdAPE1/ref-1 for 24 h in EGM-2 medium. Human recombinant TNF-{alpha} was added to appropriate wells (15 ng/ml) for 18 h before addition of labeled monocytes. Monocyte adhesion was quantified by measuring fluorescence with excitation (485 nm) and emission (535 nm) filters. Wells containing HUVEC only without U937 cells were used as blanks.

2.6 Statistical analysis
Values are expressed as the mean ± SEM. Statistical evaluation was performed using Student t test, with p<0.05 considered significant.


   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 References
 
3.1 Overexpression of APE1/ref-1 suppressed monocyte adhesion in the TNF-{alpha}-stimulated HUVECs
To explore whether APE1/ref-1 regulates monocyte adhesion, we first examined adhesion of U937 cells to TNF-{alpha}-stimulated HUVECs. As shown in Fig. 1A, un-stimulated HUVECs displayed minimal monocyte adhesion, but adhesion was increased when HUVECs were treated with TNF-{alpha}. In contrast, APE1/ref-1-overexpressing HUVECs displayed significant attenuation of monocyte adhesion induced by TNF-{alpha} in a dose dependent manner within the range of 10~200 MOI of AdAPE1/ref-1. However, overexpression of APE1/ref-1 did not affect monocyte adhesion to HUVECs in the absence of TNF-{alpha}, suggesting that overexpression of APE1/ref-1 selectively prevents endothelium–monocyte adhesion stimulated by TNF-{alpha}. Quantitative analysis of monocyte adhesion assay was plotted as U937 cells per square millimeter in Fig. 1B.


Figure 1
View larger version (41K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1 APE1/ref-1 overexpression inhibits U937 monocyte adhesion in the TNF-{alpha}-stimulated HUVECs. A. Fluorescent-labeled U937 monocyte adhesion in HUVECs infected with Adβgal or AdAPE1/ref-1. HUVEC treated with 200 MOI of adenovirus for 48 h and for 18 h with TNF-{alpha} (15 ng/ml) incubated with fluorescent-labeled U937 monocyte for 30 min. (a) Adβgal (200 MOI); (b) APE1/ref-1 (200 MOI); (c) Adβgal (200 MOI)+TNF-{alpha}; (d) AdAPE1/ref-1(10 MOI)+TNF-{alpha}; (e) AdAPE1/ref-1(50 MOI)+TNF-{alpha}; (f) AdAPE1/ref-1(200 MOI)+TNF-{alpha}. d, e, f: used total adenoviral concentration in each experiment was 200 MOI, and it was balanced with Adβgal. B. Summarized data was plotted. The values of monocyte adhesion represent U937 cell per square millimeter. The data are the mean ± SEM for 5 separate experiments. *p<0.05 compared with TNF-{alpha} alone in Adβgal-transfected cells.

 
3.2 APE1/ref-1 overexpression decreases TNF-{alpha}-induced VCAM-1 in HUVECs
VCAM-1 expression was not detected in un-stimulated endothelial cells, but treatment with TNF-{alpha} resulted in a marked increase in VCAM-1 expression. Since APE1/ref-1 inhibited monocyte adhesion to TNF-{alpha}-stimulated endothelial cells, the effect of APE1/ref-1 overexpression on TNF-{alpha}-induced VCAM-1 expression was investigated. HUVEC were infected with AdAPE1/ref-1 at various MOI for 24 h and APE1/ref-1 over-expression confirmed with Western blot analysis. As shown in Fig. 2A, high levels of APE1/ref-1 were expressed in a dose-dependent manner in AdAPE1/ref-1-infected cells but not in cells infected with Adβgal as a control virus. Adenoviral transfection with the control Adβgal (200 MOI) did not induce VCAM-1 expression. However, adenoviral overexpression of APE1/ref-1 inhibited TNF-{alpha}-induced induction of VCAM-1 in a dose dependent manner (Fig. 2B).


Figure 2
View larger version (15K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 2 APE1/ref-1 overexpression inhibits VCAM-1 in the TNF-{alpha}-stimulated HUVECs. A. APE1/ref-1 overexpression inhibits VCAM-1 expression induced by TNF-{alpha} (15 ng/ml) in a dose dependent manner at the range of 10~200 MOI. Used total adenoviral concentration in each experiment was 200 MOI, and it was balanced with Adβgal. VCAM-1 and APE1/ref-1 levels were determined by Western blot. β-actin is shown as a loading control. B. Summarized data was plotted. Densitometry data represents the mean ± SEM for 3 separate experiments. *p<0.05 compared with TNF-{alpha} alone in Adβgal -transfected cells.

 
3.3 Nitric oxide mediates APE1/ref-1-induced suppression of VCAM-1 expression
NO has been demonstrated to attenuate VCAM-1 expression in endothelial cells [11,12]. We have recently shown that APE1/rEF-1 increases endothelial NO production via H-ras/Akt/eNOS pathway in endothelial cells [9]. Therefore, we investigated whether nitric oxide is involved in APE1/ref-1 mediated suppression of VCAM-1. As shown in Fig. 3, phosphorylation of serine 1177 residue of eNOS, the target residue for Akt-dependent phosphorylation, was increased by overexpression of APE1/ref-1, suggesting that APE1/ref-1 activates eNOS via phosphorylation of eNOS at this residue. Pretreatment with L-NAME, an inhibitor of endothelial nitric oxide synthase, did not affect TNF-{alpha}-induced VCAM-1 expression, but significantly diminished APE1/ref-1-mediated suppression of VCAM-1 expression. This result suggests that NO is involved in APE1/ref-1 induced suppression of VCAM-1.


Figure 3
View larger version (21K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 3 Nitric oxide is involved in the APE1/ref-1-mediated suppression of VCAM-1. Cells was pre-treated with 0.1 mM L-NAME for 30 min, which inhibited endothelial nitric oxide synthase, then was stimulated with 15 ng/ml of TNF-{alpha} for 18 h in the Adβgal or AdAPE1/ref-1 overexpressing HUVEC. β-actin is shown as a loading control. VCAM-1, APE1/ref-1, and phospho-eNOS levels were determined by Western blot. Densitometry data of VCAM-1 represents the mean ± SEM for 3 separate experiments.

 
3.4 Overexpression of APE1/ref-1 reduces superoxide anion production in TNF-{alpha}-treated HUVECs
It is well known that oxidative stress is an important intracellular signaling mediator for VCAM-1 expression in the endothelial cells. Therefore, we also investigated whether overexpression of APE1/ref-1 suppressed superoxide production induced by TNF-{alpha}. APE1/ref-1 overexpression significantly suppressed TNF-{alpha}-induced increase in intracellular superoxide without affecting basal superoxide levels in HUVECs (Fig. 4A). Densitometric data was plotted in Fig. 4B. We also investigated whether the suppression of superoxide production by APE1/ref-1 is mediated by upregulation of superoxide dismutases (SOD) (Fig. 4C). Overexpression of APE1/ref-1 did not affect the expression of Cu/Zn SOD. However, overexpression of APE1/ref-1 did decrease expression of Mn SOD. Since the expression of Mn SOD normally is induced by superoxide, this finding supports the hypothesis of APE1/ref-1 having antioxidant activity.


Figure 4
View larger version (30K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 4 APE1/ref-1 suppressed the superoxide production by TNF-{alpha}. A. Effect of APE1/ref-1 overexpression on the superoxide production induced by TNF-{alpha} (15 ng/ml). Superoxide production was measured by the DHE staining as described in Methods. Densitometry data was plotted in Fig. 4B. The data are the mean ± SEM for 3 separate experiments. *p<0.05 compared with TNF-{alpha} alone. C. Effect of APE1/ref-1 overexpression on the Mn SOD and Cu/Zn SOD in the response of TNF-{alpha} in HUVECs. Mn SOD, Cu/Zn SOD, and APE1/ref-1 levels were determined by Western blot. {alpha}-actin is shown as a loading control.

 
3.5 APE1/ref-1 overexpression inhibited p38 phosphorylation in TNF-{alpha}-stimulated HUVECs
To determine the role of APE1/ref-1 on the p38 MAPK activation induced by TNF-{alpha}, HUVECs were transfected with AdAPE1/ref-1 or Adβgal (as a control). As shown in Fig. 5, p38 MAPK phosphorylation was significantly increased after 20 min treatment with TNF-{alpha}. However, overexpression of APE1/ref-1 inhibited basal and TNF-{alpha}-induced p38 MAPK phosphorylation in HUVECs.


Figure 5
View larger version (25K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 5 APE1/ref-1 overexpression reduced p38 MAPK induced by TNF-{alpha}. After twenty-four hours after adenoviral overexpression of APE1/ref-1, TNF-{alpha} (15 ng/ml) was treated for various times, and effect of APE1/ref-1 on the p38 phosphorylation was analyzed with Western blot analysis. Densitometry data represents the mean ± SEM for 3 separate experiments. *p<0.05 compared with Adβgal-transfected cells.

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
References
 
APE1/ref-1 has been implicated in protection against cell death resulting from oxidative stimuli [13,14]. Depletion of APE1/ref-1 renders cells more sensitive to hypoxia [15], and a decrease in APE1/ref-1 expression is associated with apoptosis in ischemic neuronal tissue [16]. In addition, APE1/ref-1 is capable of initiating the repair of apurinic/apyrymidinic sites in damaged DNA. However, the physiological role of APE1/ref-1 on monocyte adhesion to endothelial cells which is the initial event of vascular inflammation is not known. This study shows that overexpression of APE1/ref-1 suppresses TNF-{alpha}-induced expression of VCAM-1 in endothelial cells, and consequent monocyte adhesion.

Expression of adhesion molecules accelerates the adhesion and migration of monocytes toward sites of inflammation in response to a variety of stimuli. Particularly, cellular adhesion molecules are an important components in atherosclerosis and the response to vascular injury [17]. Histological studies demonstrate increased endothelial expression of VCAM-1 and intracellular adhesion molecule-1 (ICAM-1) in developing and established atherosclerotic lesions [18,19]. Early atherosclerotic events and the initiation of lesion formation appear particularly dependent on VCAM-1 [20]. Furthermore, Dansky and colleagues' findings in Vcam1D4D/D4DApoe–/– mice [21] suggested a major role for VCAM-1 in the initiation of atherosclerotic process. This likely reflects an important function for VCAM-1 in recruitment of monocytes to the arterial intima.

We previously reported that APE1/ref-1 regulates endothelial nitric oxide production and vascular tone via the upregulation of H-ras/phosphoinositide-3 kinase/Akt kinase/eNOS pathway [9]. Interestingly, its nitric oxide donors inhibit cytokine-induced VCAM-1 expression in the endothelial cells [11]. In the present study, APE1/ref-1-stimulated suppression of VCAM-1 was inhibited by the NOS inhibitor L-NAME, suggesting that increased nitric oxide production, likely by endothelial NOS, is responsible for the effect of APE1/ref-1 is contributed to reduce VCAM-1 expression induced by TNF-{alpha}.

It is also noteworthy that activation of VCAM-1 expression is redox-sensitive, with compounds with antioxidant properties inhibiting VCAM-1 expression [22]. Our results suggest that APE1/ref-1 suppresses superoxide production in TNF-{alpha} in endothelial cells and are consistent with previous observations [7]. Therefore, the effect of APE1/ref-1 on VCAM-1 expression may also be partly dependent on this mechanism of action. It should be noted however, that APE1/ref-1 did not up-regulate antioxidant enzymes such as SOD. On the contrary, it decreased the expression of Mn SOD which was up-regulated by superoxide. This result suggests that APE1/ref-1 decreases ROS generation via an SOD-independent mechanism. Previously, it was reported that APE1/ref-1 overexpression suppressed oxidative stress via inhibiting the rac1 GTPase [8]. Therefore, attenuation of superoxide production induced by APE1/ref-1 might be due to inhibition of TNF-{alpha}-induced rac1 activation.

Stimuli that result in oxidative stress employ a number of cellular ROS generating systems. Among these is the NADPH oxidase regulated by the ubiquitous small GTPase rac1. The functional significance of this oxidase is evident by the fact that rac1-regulates the production of ROS in a variety of cell types in response to a many oxidative stimuli such as TNF-{alpha} [23] and hypoxia/reoxygenation [24].

In mammalian cells, MAPKs are strongly activated by growth factors, environmental stresses and inflammatory cytokines [25]. TNF-{alpha} can activate MAPKs in the signaling pathway leading to expression of several cytokines [26]. In the present study, p38 MAPK was activated by TNF-{alpha}. However, this activation of MAPK was partially blocked by the overexpression of APE1/ref-1 in endothelial cells. This finding suggests that inhibition of p38 MAPK might be due to APE1/ref-1-mediated decrease of ROS production.

In summary, this report shows that APE1/ref-1 has an important function in suppressing monocyte adhesion and VCAM-1, through a NOS-dependent mechanism, and by reducing intracellular oxidative stress in endothelial cells. Considering the biological functions of APE1/ref-1 presented in these studies, it is tempting to speculate that endogenous vascular APE1/ref-1 might serve an anti-inflammatory role.


   Acknowledgements
 
This work was supported by grants from the Basic Research Program (R01-2004-000-10045-0) of Korea Science and Engineering Foundation, the NIH (R01 HL70929 to K.I.), and partly supported by research fund of Chungnam National University in 2004.


   Notes
 
Time for primary review 21 days


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 

  1. Ross R. Cell biology of atherosclerosis. Annu Rev Physiol (1995) 57:791–804.[CrossRef][ISI][Medline]
  2. Ross R. Atherosclerosis–an inflammatory disease. N Engl J Med (1999) 340:115–126.[Free Full Text]
  3. Harrison D., Griendling K.K., Landmesser U., Hornig B., Drexler H. Role of oxidative stress in atherosclerosis. Am J Cardiol (2003) 91:7A–11A.[CrossRef][ISI][Medline]
  4. Xanthoudakis S., Miao G.G., Curran T. The redox and DNA-repair activities of Ref-1 are encoded by nonoverlapping domains. Proc Natl Acad Sci U S A (1994) 91:23–27.[Abstract/Free Full Text]
  5. Xanthoudakis S., Curran T. Identification and characterization of Ref-1, a nuclear protein that facilitates AP-1 DNA-binding activity. EMBO J (1992) 11:653–665.[ISI][Medline]
  6. Evans A.R., Limp-Foster M., Kelley M.R. Going APE over ref-1. Mutat Res (2000) 461:83–108.[ISI][Medline]
  7. Angkeow P., Deshpande S.S., Qi B., Liu Y.X., Park Y.C., Jeon B.H., et al. Redox factor-1: an extra-nuclear role in the regulation of endothelial oxidative stress and apoptosis. Cell Death Differ (2002) 9:717–725.[CrossRef][ISI][Medline]
  8. Ozaki M., Suzuki S., Irani K. Redox factor-1/APE suppresses oxidative stress by inhibiting the rac1 GTPase. FASEB J (2002) 16:889–890.[Abstract/Free Full Text]
  9. Jeon B.H., Gupta G., Park Y.C., Qi B., Haile A., Khanday F.A., et al. Apurinic/apyrmidinic endonuclease 1 regulates endothelial NO production and vascular tone. Circ Res (2004) 95:902–910.[Abstract/Free Full Text]
  10. Martinet W., Knaapen M.W., De Meyer G.R., Herman A.G., Kockx M.M. Elevated levels of oxidative DNA damage and DNA repair enzymes in human atherosclerotic plaques. Circulation (2002) 106:927–932.[Abstract/Free Full Text]
  11. De Caterina R., Libby P., Peng H.B., Thannickal V.J., Rajavashisth T.B., Gimbrone M.A. Jr., et al. Nitric oxide decreases cytokine-induced endothelial activation. Nitric oxide selectively reduces endothelial expression of adhesion molecules and proinflammatory cytokines. J Clin Invest (1995) 96:60–68.[ISI][Medline]
  12. Zampolli A., Basta G., Lazzerini G., Feelisch M., De Caterina R. Inhibition of endothelial cell activation by nitric oxide donors. J Pharmacol Exp Ther (2000) 295:818–823.[Abstract/Free Full Text]
  13. Xanthoudakis S., Smeyne R.J., Wallace J.D., Curran T. The redox/DNA repair protein, Ref-1, is essential for early embryonic development in mice. Proc Natl Acad Sci U S A (1996) 93:8919–8923.[Abstract/Free Full Text]
  14. Silber J.R., Bobola M.S., Blank A., Schoeler K.D., Haroldson P.D., Huynh M.B., et al. The apurinic/apyrimidinic endonuclease activity of Ape1/Ref-1 contributes to human glioma cell resistance to alkylating agents and is elevated by oxidative stress. Clin Cancer Res (2002) 8:3008–3018.[Abstract/Free Full Text]
  15. Walker L.J., Craig R.B., Harris A.L., Hickson I.D. A role for the human DNA repair enzyme HAP1 in cellular protection against DNA damaging agents and hypoxic stress. Nucleic Acids Res (1994) 22:4884–4889.[Abstract/Free Full Text]
  16. Walton M., Lawlor P., Sirimanne E., Williams C., Gluckman P., Dragunow M. Loss of Ref-1 protein expression precedes DNA fragmentation in apoptotic neurons. Brain Res Mol Brain Res (1997) 44:167–170.[Medline]
  17. Huo Y., Ley K. Adhesion molecules and atherogenesis. Acta Physiol Scand (2001) 173:35–43.[CrossRef][ISI][Medline]
  18. Li H., Cybulsky M.I., Gimbrone M.A. Jr., Libby P. An atherogenic diet rapidly induces VCAM-1, a cytokine-regulatable mononuclear leukocyte adhesion molecule, in rabbit aortic endothelium. Arterioscler Thromb (1993) 13:197–204.[Abstract/Free Full Text]
  19. Poston R.N., Haskard D.O., Coucher J.R., Gall N.P., Johnson-Tidey R.R. Expression of intercellular adhesion molecule-1 in atherosclerotic plaques. Am J Pathol (1992) 140:665–673.[Abstract]
  20. Cybulsky M.I., Iiyama K., Li H., Zhu S., Chen M., Iiyama M., et al. A major role for VCAM-1, but not ICAM-1, in early atherosclerosis. J Clin Invest (2001) 107:1255–1262.[ISI][Medline]
  21. Dansky H.M., Barlow C.B., Lominska C., Sikes J.L., Kao C., Weinsaft J., et al. Adhesion of monocytes to arterial endothelium and initiation of atherosclerosis are critically dependent on vascular cell adhesion molecule-1 gene dosage. Arterioscler Thromb Vasc Biol (2001) 21:1662–1667.[Abstract/Free Full Text]
  22. Fruebis J., Silvestre M., Shelton D., Napoli C., Palinski W. Inhibition of VCAM-1 expression in the arterial wall is shared by structurally different antioxidants that reduce early atherosclerosis in NZW rabbits. J Lipid Res (1999) 40:1958–1966.[Abstract/Free Full Text]
  23. Deshpande S.S., Angkeow P., Huang J., Ozaki M., Irani K. Rac1 inhibits TNF-alpha-induced endothelial cell apoptosis: dual regulation by reactive oxygen species. FASEB J (2000) 14:1705–1714.[Abstract/Free Full Text]
  24. Kim K.S., Takeda K., Sethi R., Pracyk J.B., Tanaka K., Zhou Y.F., et al. Protection from reoxygenation injury by inhibition of rac1. J Clin Invest (1998) 101:1821–1826.[ISI][Medline]
  25. Chen Z., Gibson T.B., Robinson F., Silvestro L., Pearson G., Xu B., et al. MAP kinases. Chem Rev (2001) 101:2449–2476.[CrossRef][ISI][Medline]
  26. Baud V., Karin M. Signal transduction by tumor necrosis factor and its relatives. Trends Cell Biol (2001) 11:372–377.[CrossRef][ISI][Medline]

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Kim, C. S.
Right arrow Articles by Jeon, B. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kim, C. S.
Right arrow Articles by Jeon, B. H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?