• 作者：Lluí ; s Martorell ; Jordi Rius ; Javier Crespo ; Lina Badimon ; Cristina Rodrí ; guez ; José ; Martí ; nez-Gonzá ; lez ; ^{jmartinez@csic-iccc.org}
• 关键词：Hipoxia ; Apoptosis ; Cé ; lulas endoteliales ; Neuron-derived orphan receptor-1 ; Factor inducido por hipoxia - 1
• 刊名：Cl铆nica e Investigaci贸n en Arteriosclerosis
• 出版年：2010
• 期刊代码：pca88_02149168
• 类别：med
• 出版时间：March-April 2010
• 卷：22
• 期：2
• 页码：39-48
• 文件大小：580 K

Background

NOR-1 is a nuclear receptor that is overexpressed in human atherosclerotic plaques. This receptor is involved in endothelial cell (EC) growth induced by vascular endothelial growth factor (VEGF) and other mitogens. Our aim was to analyze NOR-1 regulation by hypoxia in EC.

Results

Hypoxia increased NOR-1 mRNA levels in a time- and dose-dependent manner. Hypoxia-induced NOR-1 expression was prevented by BAPTA-AM (a calcium chelator) but not by inhibitors of p38 MAPK, MEK1/2 or protein kinase C (PKC) pathways. Incubation of EC with blocking antibodies against VEGF or SU5614 (a VEGF-R2 inhibitor) did not prevent hypoxia-induced NOR-1 expression. Hypoxia did not significantly induce early activation of cAMP response element binding protein (CREB), a key transcription factor involved in the up-regulation of NOR-1 expression by VEGF. In contrast, reduction of hypoxia-induced HIF-1伪 protein levels by inhibitors of the PI3K/Akt/mTOR pathway or by siRNA against HIF-1, significantly counteracted hypoxia-induced NOR-1 up-regulation. In transient transfection assays, the activity of the NOR-1 promoter construct was increased by hypoxia or by co-transfection with an HIF-1伪 expression plasmid. We identified a hypoxia response element in the NOR-1 promoter responsible for this hypoxia-mediated effect as shown by site-directed mutagenesis and serial deletions. Finally, over-expression of NOR-1 (using a bicistronic recombinant plasmid) decreased the rate of cells undergoing apoptosis (annexin V positive/propidium iodide negative), while inhibition of NOR-1 (using specific siRNA) increased cell apoptosis.

Conclusions

Therefore, HIF-1 modulates the expression of NOR-1, a transcription factor that regulates the survival response of EC to hypoxia.