Hypoxia-responsive miRNAs target argonaute 1 to promote angiogenesis
Zhen Chen, … , Michael Hsiao, John Y-J. Shyy
Zhen Chen, … , Michael Hsiao, John Y-J. Shyy
Published February 15, 2013
Citation Information: J Clin Invest. 2013;123(3):1057-1067. https://doi.org/10.1172/JCI65344.
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Research Article Oncology

Hypoxia-responsive miRNAs target argonaute 1 to promote angiogenesis

Abstract

Despite a general repression of translation under hypoxia, cells selectively upregulate a set of hypoxia-inducible genes. Results from deep sequencing revealed that Let-7 and miR-103/107 are hypoxia-responsive microRNAs (HRMs) that are strongly induced in vascular endothelial cells. In silico bioinformatics and in vitro validation showed that these HRMs are induced by HIF1α and target argonaute 1 (AGO1), which anchors the microRNA-induced silencing complex (miRISC). HRM targeting of AGO1 resulted in the translational desuppression of VEGF mRNA. Inhibition of HRM or overexpression of AGO1 without the 3′ untranslated region decreased hypoxia-induced angiogenesis. Conversely, AGO1 knockdown increased angiogenesis under normoxia in vivo. In addition, data from tumor xenografts and human cancer specimens indicate that AGO1-mediated translational desuppression of VEGF may be associated with tumor angiogenesis and poor prognosis. These findings provide evidence for an angiogenic pathway involving HRMs that target AGO1 and suggest that this pathway may be a suitable target for anti- or proangiogenesis strategies.

Authors

Zhen Chen, Tsung-Ching Lai, Yi-Hua Jan, Feng-Mao Lin, Wei-Chi Wang, Han Xiao, Yun-Ting Wang, Wei Sun, Xiaopei Cui, Ying-Shiuan Li, Tzan Fang, Hongwei Zhao, Chellappan Padmanabhan, Ruobai Sun, Danny Ling Wang, Hailing Jin, Gar-Yang Chau, Hsien-Da Huang, Michael Hsiao, John Y-J. Shyy

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Figure 4

Translational desuppression of VEGF caused by AGO1 targeting.

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Translational desuppression of VEGF caused by AGO1 targeting. (A–C) HUVE...
(A–C) HUVECs were subjected to normoxia or hypoxia for the indicated times. Western blot analysis of protein levels of HIF1α (A) and AGO1 (C) and TaqMan qPCR analysis of miRNAs (B). (D) Model of translational suppression under normoxia and desuppression under hypoxia. Red arrows indicate up- or downregulation of various molecules. (E) AGO1-associated mRNAs were enriched by IP. Level of VEGF was detected by qPCR. (F) HUVECs were transfected with a mixture of anti–Let-7a/e/miR-103 (10 nM each) or control RNA (30 nM). (G) HUVECs were transfected with a control vector expressing HA or HA-AGO1-ORF plasmid containing AGO1 ORF without 3′ UTR. (H) HUVECs were transfected with AGO1 siRNA or control RNA for 48 hours, then treated with vehicle control or cycloheximide (CHX) (5 μg/ml) for 4 hours. Cells in F–H were then subjected to hypoxia or kept as normoxia controls, and various proteins were detected by Western blot analysis. *P < 0.05 compared with normoxia group.