TY - JOUR
T1 - Overexpression of ref-1 inhibits hypoxia and tumor necrosis factor-induced endothelial cell apoptosis through nuclear factor-κB-independent and -dependent pathways
AU - Hall, Jennifer L.
AU - Wang, Xiaohong
AU - Adamson, Van
AU - Zhao, Ying
AU - Gibbons, Gary H.
PY - 2001/6/22
Y1 - 2001/6/22
N2 - We hypothesized that a redox-sensitive transcription factor, redox factor-1 (Ref-1) (HAP1, APE, and APEX), was critical in the regulation of endothelial cell survival in response to hypoxia and cytokines, including tumor necrosis factor (TNF)-α. Hypoxia resulted in a significant decrease in Ref-1 protein expression in both human umbilical vein endothelial cells and calf pulmonary artery endothelial cells. The hypoxia-induced decrease in Ref-1 expression was followed by a significant induction of apoptosis as measured by caspase 3 activity and nuclear morphology. Transient upregulation of Ref-1 significantly inhibited hypoxia-induced apoptosis. However, deletion of the redox-sensitive domain of Ref-1 abolished the antiapoptotic effect. We postulated that the antiapoptotic effects of Ref-1 were mediated through nuclear factor-κB (NF-κB). However, blockade of NF-κB with a dominant-negative IκB (S32A/S36A) expression vector had no effect on Ref-1-mediated survival under hypoxic conditions. The second aim of this study was to test the cytoprotective ability of Ref-1 upregulation in response to TNF-induced apoptosis. Ref-1 inhibition of TNF-induced death was associated with a significant potentiation of NF-κB activity. Deletion of the redox-sensitive domain of Ref-1 significantly inhibited TNF-induced NF-κB activation. Moreover, loss of the redox-sensitive domain also abolished the antiapoptotic effect of Ref-1 in response to TNF. To test whether Ref-1 induced activation of NF-κB was necessary to promote survival, we blocked NF-κB activity with a dominant-negative IκB (S32A/S36A). Indeed, blockade of NF-κB activity abolished the ability of Ref-1 to rescue TNF-induced apoptosis. In conclusion, upregulation of Ref-1 promotes endothelial cell survival in response to hypoxia and TNF through NF-κB-independent and NF-κB-dependent signaling cascades, respectively. Moreover, it seems that Ref-1 may act as a critical cofactor, mediating the TNF-induced NF-κB response in the vascular endothelium.
AB - We hypothesized that a redox-sensitive transcription factor, redox factor-1 (Ref-1) (HAP1, APE, and APEX), was critical in the regulation of endothelial cell survival in response to hypoxia and cytokines, including tumor necrosis factor (TNF)-α. Hypoxia resulted in a significant decrease in Ref-1 protein expression in both human umbilical vein endothelial cells and calf pulmonary artery endothelial cells. The hypoxia-induced decrease in Ref-1 expression was followed by a significant induction of apoptosis as measured by caspase 3 activity and nuclear morphology. Transient upregulation of Ref-1 significantly inhibited hypoxia-induced apoptosis. However, deletion of the redox-sensitive domain of Ref-1 abolished the antiapoptotic effect. We postulated that the antiapoptotic effects of Ref-1 were mediated through nuclear factor-κB (NF-κB). However, blockade of NF-κB with a dominant-negative IκB (S32A/S36A) expression vector had no effect on Ref-1-mediated survival under hypoxic conditions. The second aim of this study was to test the cytoprotective ability of Ref-1 upregulation in response to TNF-induced apoptosis. Ref-1 inhibition of TNF-induced death was associated with a significant potentiation of NF-κB activity. Deletion of the redox-sensitive domain of Ref-1 significantly inhibited TNF-induced NF-κB activation. Moreover, loss of the redox-sensitive domain also abolished the antiapoptotic effect of Ref-1 in response to TNF. To test whether Ref-1 induced activation of NF-κB was necessary to promote survival, we blocked NF-κB activity with a dominant-negative IκB (S32A/S36A). Indeed, blockade of NF-κB activity abolished the ability of Ref-1 to rescue TNF-induced apoptosis. In conclusion, upregulation of Ref-1 promotes endothelial cell survival in response to hypoxia and TNF through NF-κB-independent and NF-κB-dependent signaling cascades, respectively. Moreover, it seems that Ref-1 may act as a critical cofactor, mediating the TNF-induced NF-κB response in the vascular endothelium.
KW - Apoptosis
KW - Endothelium
KW - Hypoxia
KW - Nuclear factor-κB
KW - Redox
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UR - http://www.scopus.com/inward/citedby.url?scp=0035933483&partnerID=8YFLogxK
U2 - 10.1161/hh1201.091796
DO - 10.1161/hh1201.091796
M3 - Article
C2 - 11420300
AN - SCOPUS:0035933483
SN - 0009-7330
VL - 88
SP - 1247
EP - 1253
JO - Circulation research
JF - Circulation research
IS - 12
ER -