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Zhang R, Wu Y, Zhao M, Liu C, Zhou L, Shen S, Liao S, Yang K, Li Q, Wan H. Role of HIF-1alpha in the regulation ACE and ACE2 expression in hypoxic human pulmonary artery smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2009; 297:L631-40. [PMID: 19592460 DOI: 10.1152/ajplung.90415.2008] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Angiotensin-converting enzyme (ACE) enhances the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs), which contribute to the pathogenesis of hypoxic pulmonary hypertension (HPH). Previous reports have demonstrated that hypoxia upregulates ACE expression, but the underlying mechanism is unknown. Here, we found that ACE is persistently upregulated in PASMCs on the transcriptional level during hypoxia. Hypoxia-inducible factor 1alpha (HIF-1alpha), a key transcription factor activated during hypoxia, was able to upregulate ACE protein expression under normoxia, whereas knockdown of HIF-1alpha expression in PASMCs inhibited hypoxia-induced ACE upregulation. Furthermore, HIF-1alpha can bind and transactivate the ACE promoter directly. Therefore, we report that ACE is a novel target of HIF-1alpha. Recently, a homolog of ACE, ACE2, was reported to counterbalance the function of ACE. In contrast to ACE, we found that ACE2 mRNA and protein levels increased during the early stages of hypoxia and decreased to near-baseline levels at the later stages after HIF-1alpha accumulation. Thus HIF-1alpha inhibited ACE2 expression, and the accumulated ANG II catalyzed by ACE is a key mediator in the downregulation of ACE2 by HIF-1alpha. Moreover, a reduction of ACE2 expression in PASMCs by RNA interference was accompanied by significantly enhanced proliferation and migration during hypoxia. We conclude that ACE is directly regulated by HIF-1alpha, whereas ACE2 is regulated in a bidirectional way during hypoxia and may play a protective role during the development of HPH. In sum, these findings contribute to the understanding of the pathogenesis of HPH.
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Affiliation(s)
- Ruifeng Zhang
- Dept. of Respiratory Medicine, Ruijin Hospital, Medical School of Shanghai Jiaotong Univ., No. 197, Second Ruijin Rd., Shanghai 200025, China
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56
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Adenosine A2A receptor is a unique angiogenic target of HIF-2alpha in pulmonary endothelial cells. Proc Natl Acad Sci U S A 2009; 106:10684-9. [PMID: 19541651 DOI: 10.1073/pnas.0901326106] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hypoxia, through the hypoxia-inducible transcription factors HIF-1alpha and HIF-2alpha (HIFs), induces angiogenesis by up-regulating a common set of angiogenic cytokines. Unlike HIF-1alpha, which regulates a unique set of genes, most genes regulated by HIF-2alpha overlap with those induced by HIF-1alpha. Thus, the unique contribution of HIF-2alpha remains largely obscure. By using adenoviral mutant HIF-1alpha and adenoviral mutant HIF-2alpha constructs, where the HIFs are transcriptionally active under normoxic conditions, we show that HIF-2alpha but not HIF-1alpha regulates adenosine A(2A) receptor in primary cultures of human lung endothelial cells. Further, siRNA knockdown of HIF-2alpha completely inhibits hypoxic induction of A(2A) receptor. Promoter studies show a 2.5-fold induction of luciferase activity with HIF-2alpha cotransfection. Analysis of the A(2A) receptor gene promoter revealed a hypoxia-responsive element in the region between -704 and -595 upstream of the transcription start site. By using a ChIP assay, we demonstrate that HIF-2alpha binding to this region is specific. In addition, we demonstrate that A(2A) receptor has angiogenic potential, as assessed by increases in cell proliferation, cell migration, and tube formation. Additional data show increased expression of A(2A) receptor in human lung tumor cancer samples relative to adjacent normal lung tissue. These data also demonstrate that A(2A) receptor is regulated by hypoxia and HIF-2alpha in human lung endothelial cells but not in mouse-derived endothelial cells.
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57
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De Bock K, De Smet F, Leite De Oliveira R, Anthonis K, Carmeliet P. Endothelial oxygen sensors regulate tumor vessel abnormalization by instructing phalanx endothelial cells. J Mol Med (Berl) 2009; 87:561-9. [PMID: 19455291 DOI: 10.1007/s00109-009-0482-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 04/23/2009] [Accepted: 04/23/2009] [Indexed: 01/07/2023]
Abstract
An ancestral function of vessels is to conduct blood flow and supply oxygen (O(2)). In hypoxia, cells secrete angiogenic factors to initiate vessel sprouting. Angiogenic factors are balanced off by inhibitors, ensuring that vessels form optimally and supply sufficient oxygen (O(2)). By contrast, in tumors, excessive production of angiogenic factors induces vessels and their endothelial cell (EC) layer to become highly abnormal, thereby impairing tumor perfusion and oxygenation. In such pathological conditions, angiogenic factors act as "abnormalization factors" and promote the vessel "abnormalization switch." Recent genetic data indicate that ECs sense an imbalance in oxygen levels, by using the oxygen-sensing prolyl hydroxylase PHD2. In conditions of O(2) shortage, a decrease in PHD2 activity in ECs initiates a feedback that restores their shape, not their numbers. This induces ECs to align in a streamlined "phalanx" of tightly apposed, regularly ordered cobblestone ECs, which improves perfusion and oxygenation. As a result, EC normalization in PHD2 haplodeficient tumor vessels improves oxygenation and renders tumor cells less invasive and metastatic. This review discusses the role of PHD2 in the regulation of vessel (ab)normalization and the therapeutic potential of PHD2 inhibition for tumor invasiveness and metastasis.
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59
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Fong GH. Regulation of angiogenesis by oxygen sensing mechanisms. J Mol Med (Berl) 2009; 87:549-60. [PMID: 19288062 DOI: 10.1007/s00109-009-0458-z] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 12/26/2022]
Abstract
The choices for blood vessels to undergo angiogenesis or stay quiescent are mostly determined by the status of tissue oxygenation. A major link between tissue hypoxia and active angiogenesis is the accumulation of hypoxia-inducible factor (HIF)-alpha subunits which play a major role in the transcriptional activation of genes encoding angiogenic factors. HIF-alpha abundance is negatively regulated by a subfamily of dioxygenases referred to as prolyl hydroxylase domain-containing proteins (PHDs) which use O(2) as a substrate to hydroxylate HIF-alpha subunits and hence tag them for rapid degradation. Under hypoxic conditions, HIF-alpha subunits accumulate due to reduced hydroxylation efficiency and form transcriptionally active heterodimers with HIF-1ss to activate the expression of angiogenic factors and other proteins important for cellular adaptation to hypoxia. Angiogenesis is regulated by a combination of at least two different mechanisms. The paracrine mechanism is mediated by non-endothelial expression of angiogenic factors such as vascular endothelial growth factor (VEGF)-A, which in turn interact with endothelial cell surface receptors to initiate angiogenic activities. In the autocrine mechanism, endothelial cell themselves are induced to express VEGF-A, which collaborate with the paracrine mechanism to support angiogenesis and protect vascular integrity. Because of critical roles of PHDs and HIFs in regulating angiogenic activities, studies are underway to assess their candidacy as targets for angiogenesis therapies.
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Affiliation(s)
- Guo-Hua Fong
- Center for Vascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, 06030, USA.
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60
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Mazzone M, Dettori D, de Oliveira RL, Loges S, Schmidt T, Jonckx B, Tian YM, Lanahan AA, Pollard P, de Almodovar CR, De Smet F, Vinckier S, Aragonés J, Debackere K, Luttun A, Wyns S, Jordan B, Pisacane A, Gallez B, Lampugnani MG, Dejana E, Simons M, Ratcliffe P, Maxwell P, Carmeliet P. Heterozygous deficiency of PHD2 restores tumor oxygenation and inhibits metastasis via endothelial normalization. Cell 2009; 136:839-851. [PMID: 19217150 DOI: 10.1016/j.cell.2009.01.020] [Citation(s) in RCA: 594] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 12/01/2008] [Accepted: 01/15/2009] [Indexed: 01/03/2023]
Abstract
A key function of blood vessels, to supply oxygen, is impaired in tumors because of abnormalities in their endothelial lining. PHD proteins serve as oxygen sensors and may regulate oxygen delivery. We therefore studied the role of endothelial PHD2 in vessel shaping by implanting tumors in PHD2(+/-) mice. Haplodeficiency of PHD2 did not affect tumor vessel density or lumen size, but normalized the endothelial lining and vessel maturation. This resulted in improved tumor perfusion and oxygenation and inhibited tumor cell invasion, intravasation, and metastasis. Haplodeficiency of PHD2 redirected the specification of endothelial tip cells to a more quiescent cell type, lacking filopodia and arrayed in a phalanx formation. This transition relied on HIF-driven upregulation of (soluble) VEGFR-1 and VE-cadherin. Thus, decreased activity of an oxygen sensor in hypoxic conditions prompts endothelial cells to readjust their shape and phenotype to restore oxygen supply. Inhibition of PHD2 may offer alternative therapeutic opportunities for anticancer therapy.
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Affiliation(s)
- Massimiliano Mazzone
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Daniela Dettori
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.,Laboratory of Cancer Genetics, Institute for Cancer Research and Treatment, University of Turin Medical School, 10060 Candiolo, Turin, Italy
| | - Rodrigo Leite de Oliveira
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Sonja Loges
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Thomas Schmidt
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Bart Jonckx
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Ya-Min Tian
- The Henry Wellcome Building of Genomic Medicine, Oxford OX3 7BN, UK
| | | | - Patrick Pollard
- The Henry Wellcome Building of Genomic Medicine, Oxford OX3 7BN, UK
| | - Carmen Ruiz de Almodovar
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Frederik De Smet
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Stefan Vinckier
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Julián Aragonés
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Koen Debackere
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Aernout Luttun
- Center for Molecular and Vascular Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Sabine Wyns
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Benedicte Jordan
- Biomedical Magnetic Resonance Unit, Medicinal Chemistry and Radiopharmacy U.C. Louvain, 1000 Brussels, Belgium
| | - Alberto Pisacane
- Unit of Pathological Anatomy, Institute for Cancer Research and Treatment, 10060 Candiolo, Turin, Italy
| | - Bernard Gallez
- Biomedical Magnetic Resonance Unit, Medicinal Chemistry and Radiopharmacy U.C. Louvain, 1000 Brussels, Belgium
| | - Maria Grazia Lampugnani
- Vascular Biology Unit, Italian Foundation for Cancer Research Institute of Molecular Oncology, 20139 Milan, Italy
| | - Elisabetta Dejana
- Vascular Biology Unit, Italian Foundation for Cancer Research Institute of Molecular Oncology, 20139 Milan, Italy
| | - Michael Simons
- Cardiovascular Medicine, Yale University, New Haven, CT 06510, USA
| | - Peter Ratcliffe
- The Henry Wellcome Building of Genomic Medicine, Oxford OX3 7BN, UK
| | - Patrick Maxwell
- Rayne Institute, University College London, London WC1E 6JJ, UK
| | - Peter Carmeliet
- Vesalius Research Center, VIB-Vlaams Instituut voor Biotechnologie, 3000 Leuven, Belgium.,Vesalius Research Center, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
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62
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Zhang R, Zhou L, Li Q, Liu J, Yao W, Wan H. Up-regulation of two actin-associated proteins prompts pulmonary artery smooth muscle cell migration under hypoxia. Am J Respir Cell Mol Biol 2009; 41:467-75. [PMID: 19188659 DOI: 10.1165/rcmb.2008-0333oc] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Hypoxia stimulates the migration of pulmonary artery smooth muscle cells (PASMCs), which contributes to the pathogenesis of pulmonary vessel structural remodeling in hypoxic pulmonary hypertension (HPH). In the present study, we found, using a proteomics-based method, that gelsolin-like actin-capping protein (CapG) and transgelin were preferentially expressed in human (h)PAMSCs under hypoxia compared with normoxia. These two actin-associated proteins, modulate a variety of physiologic processes, including motility of cells, by interacting differently with the actin cytoskeleton. Our study showed that these two genes were up-regulated at both mRNA and protein levels under hypoxia in hPASMCs. As a key transcriptional regulation factor under hypoxia, hypoxia-inducible factor 1alpha (HIF-1alpha) up-regulated CapG protein expression under normoxia, and knockdown of HIF-1alpha expression in hPASMCs also inhibited hypoxia induced CapG up-regulation. However, HIF-1alpha could not regulate transgelin expression. Reduction of CapG or transgelin expression in hPASMCs by RNA interference was accompanied by significantly impaired migration ability in vitro, especially under hypoxia. Our study demonstrates that CapG and transgelin were preferentially expressed in hPAMSCs under hypoxia compared with normoxia. Hypoxia stimulates expression of these two actin-associated proteins via HIF-1alpha-dependent and -independent pathways, respectively. The up-regulation of these two proteins may contribute to the increased motility of hPASMCs under hypoxia. These findings may contribute to the understanding of the pathogenesis of HPH.
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Affiliation(s)
- Ruifeng Zhang
- Department of Respiratory Medicine, Ruijin Hospital, Medical School of Shanghai Jiaotong University, N0.197, The Second Ruijin Road, Shanghai, 200025, China
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63
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Noberini R, Koolpe M, Peddibhotla S, Dahl R, Su Y, Cosford NDP, Roth GP, Pasquale EB. Small molecules can selectively inhibit ephrin binding to the EphA4 and EphA2 receptors. J Biol Chem 2008; 283:29461-72. [PMID: 18728010 DOI: 10.1074/jbc.m804103200] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The erythropoietin-producing hepatocellular (Eph) family of receptor tyrosine kinases regulates a multitude of physiological and pathological processes. Despite the numerous possible research and therapeutic applications of agents capable of modulating Eph receptor function, no small molecule inhibitors targeting the extracellular domain of these receptors have been identified. We have performed a high throughput screen to search for small molecules that inhibit ligand binding to the extracellular domain of the EphA4 receptor. This yielded a 2,5-dimethylpyrrolyl benzoic acid derivative able to inhibit the interaction of EphA4 with a peptide ligand as well as the natural ephrin ligands. Evaluation of a series of analogs identified an isomer with similar inhibitory properties and other less potent compounds. The two isomeric compounds act as competitive inhibitors, suggesting that they target the high affinity ligand-binding pocket of EphA4 and inhibit ephrin-A5 binding to EphA4 with K(i) values of 7 and 9 mum in enzyme-linked immunosorbent assays. Interestingly, despite the ability of each ephrin ligand to promiscuously bind many Eph receptors, the two compounds selectively target EphA4 and the closely related EphA2 receptor. The compounds also inhibit ephrin-induced phosphorylation of EphA4 and EphA2 in cells, without affecting cell viability or the phosphorylation of other receptor tyrosine kinases. Furthermore, the compounds inhibit EphA4-mediated growth cone collapse in retinal explants and EphA2-dependent retraction of the cell periphery in prostate cancer cells. These data demonstrate that the Eph receptor-ephrin interface can be targeted by inhibitory small molecules and suggest that the two compounds identified will be useful to discriminate the activities of EphA4 and EphA2 from those of other co-expressed Eph receptors that are activated by the same ephrin ligands. Furthermore, the newly identified inhibitors represent possible leads for the development of therapies to treat pathologies in which EphA4 and EphA2 are involved, including nerve injuries and cancer.
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Affiliation(s)
- Roberta Noberini
- Burnham Institute for Medical Research, La Jolla, California 92037, USA
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