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Hoque ME, Mahendran T, Basu S. Reversal of G-Quadruplexes' Role in Translation Control When Present in the Context of an IRES. Biomolecules 2022; 12:314. [PMID: 35204814 PMCID: PMC8869680 DOI: 10.3390/biom12020314] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/08/2022] [Accepted: 02/14/2022] [Indexed: 02/01/2023] Open
Abstract
G-quadruplexes (GQs) are secondary nucleic acid structures that play regulatory roles in various cellular processes. G-quadruplex-forming sequences present within the 5' UTR of mRNAs can function not only as repressors of translation but also as elements required for optimum function. Based upon previous reports, the majority of the 5' UTR GQ structures inhibit translation, presumably by blocking the ribosome scanning process that is essential for detection of the initiation codon. However, there are certain mRNAs containing GQs that have been identified as positive regulators of translation, as they are needed for translation initiation. While most cellular mRNAs utilize the 5' cap structure to undergo cap-dependent translation initiation, many rely on cap-independent translation under certain conditions in which the cap-dependent initiation mechanism is not viable or slowed down, for example, during development, under stress and in many diseases. Cap-independent translation mainly occurs via Internal Ribosomal Entry Sites (IRESs) that are located in the 5' UTR of mRNAs and are equipped with structural features that can recruit the ribosome or other factors to initiate translation without the need for a 5' cap. In this review, we will focus only on the role of RNA GQs present in the 5' UTR of mRNAs, where they play a critical role in translation initiation, and discuss the potential mechanism of this phenomenon, which is yet to be fully delineated.
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Affiliation(s)
| | | | - Soumitra Basu
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA; (M.E.H.); (T.M.)
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2
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Niu K, Zhang X, Song Q, Feng Q. G-Quadruplex Regulation of VEGFA mRNA Translation by RBM4. Int J Mol Sci 2022; 23:ijms23020743. [PMID: 35054929 PMCID: PMC8776124 DOI: 10.3390/ijms23020743] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/01/2023] Open
Abstract
In eukaryotes, mRNAs translation is mainly mediated in a cap-dependent or cap-independent manner. The latter is primarily initiated at the internal ribosome entry site (IRES) in the 5'-UTR of mRNAs. It has been reported that the G-quadruplex structure (G4) in the IRES elements could regulate the IRES activity. We previously confirmed RBM4 (also known as LARK) as a G4-binding protein in human. In this study, to investigate whether RBM4 is involved in the regulation of the IRES activity by binding with the G4 structure within the IRES element, the IRES-A element in the 5'-UTR of vascular endothelial growth factor A (VEGFA) was constructed into a dicistronic reporter vector, psiCHECK2, and the effect of RBM4 on the IRES activity was tested in 293T cells. The results showed that the IRES insertion significantly increased the FLuc expression activity, indicating that this G4-containing IRES was active in 293T cells. When the G4 structure in the IRES was disrupted by base mutation, the IRES activity was significantly decreased. The IRES activity was notably increased when the cells were treated with G4 stabilizer PDS. EMSA results showed that RBM4 specifically bound the G4 structure in the IRES element. The knockdown of RBM4 substantially reduced the IRES activity, whereas over-expressing RBM4 increased the IRES activity. Taking all results together, we demonstrated that RBM4 promoted the mRNA translation of VEGFA gene by binding to the G4 structure in the IRES.
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Affiliation(s)
- Kangkang Niu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China; (K.N.); (X.Z.)
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaojuan Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China; (K.N.); (X.Z.)
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Qisheng Song
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA;
| | - Qili Feng
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China; (K.N.); (X.Z.)
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
- Correspondence:
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3
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Jaud M, Philippe C, Di Bella D, Tang W, Pyronnet S, Laurell H, Mazzolini L, Rouault-Pierre K, Touriol C. Translational Regulations in Response to Endoplasmic Reticulum Stress in Cancers. Cells 2020; 9:cells9030540. [PMID: 32111004 PMCID: PMC7140484 DOI: 10.3390/cells9030540] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/18/2020] [Accepted: 02/24/2020] [Indexed: 12/20/2022] Open
Abstract
During carcinogenesis, almost all the biological processes are modified in one way or another. Among these biological processes affected, anomalies in protein synthesis are common in cancers. Indeed, cancer cells are subjected to a wide range of stresses, which include physical injuries, hypoxia, nutrient starvation, as well as mitotic, oxidative or genotoxic stresses. All of these stresses will cause the accumulation of unfolded proteins in the Endoplasmic Reticulum (ER), which is a major organelle that is involved in protein synthesis, preservation of cellular homeostasis, and adaptation to unfavourable environment. The accumulation of unfolded proteins in the endoplasmic reticulum causes stress triggering an unfolded protein response in order to promote cell survival or to induce apoptosis in case of chronic stress. Transcription and also translational reprogramming are tightly controlled during the unfolded protein response to ensure selective gene expression. The majority of stresses, including ER stress, induce firstly a decrease in global protein synthesis accompanied by the induction of alternative mechanisms for initiating the translation of mRNA, later followed by a translational recovery. After a presentation of ER stress and the UPR response, we will briefly present the different modes of translation initiation, then address the specific translational regulatory mechanisms acting during reticulum stress in cancers and highlight the importance of translational control by ER stress in tumours.
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Affiliation(s)
- Manon Jaud
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), F-31037 Toulouse, France; (M.J.); (S.P.); (L.M.)
- Université Toulouse III Paul-Sabatier, F-31000 Toulouse, France;
| | - Céline Philippe
- Barts Cancer Institute, Queen Mary University of London, London E1 4NS, UK; (C.P.); (D.D.B.); (W.T.); (K.R.-P.)
| | - Doriana Di Bella
- Barts Cancer Institute, Queen Mary University of London, London E1 4NS, UK; (C.P.); (D.D.B.); (W.T.); (K.R.-P.)
| | - Weiwei Tang
- Barts Cancer Institute, Queen Mary University of London, London E1 4NS, UK; (C.P.); (D.D.B.); (W.T.); (K.R.-P.)
| | - Stéphane Pyronnet
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), F-31037 Toulouse, France; (M.J.); (S.P.); (L.M.)
- Université Toulouse III Paul-Sabatier, F-31000 Toulouse, France;
| | - Henrik Laurell
- Université Toulouse III Paul-Sabatier, F-31000 Toulouse, France;
- Inserm UMR1048, I2MC (Institut des Maladies Métaboliques et Cardiovasculaires), BP 84225, CEDEX 04, 31 432 Toulouse, France
| | - Laurent Mazzolini
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), F-31037 Toulouse, France; (M.J.); (S.P.); (L.M.)
- CNRS ERL5294, CRCT, F-31037 Toulouse, France
| | - Kevin Rouault-Pierre
- Barts Cancer Institute, Queen Mary University of London, London E1 4NS, UK; (C.P.); (D.D.B.); (W.T.); (K.R.-P.)
| | - Christian Touriol
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), F-31037 Toulouse, France; (M.J.); (S.P.); (L.M.)
- Université Toulouse III Paul-Sabatier, F-31000 Toulouse, France;
- Correspondence:
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4
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Jaud M, Philippe C, Van Den Berghe L, Ségura C, Mazzolini L, Pyronnet S, Laurell H, Touriol C. The PERK Branch of the Unfolded Protein Response Promotes DLL4 Expression by Activating an Alternative Translation Mechanism. Cancers (Basel) 2019; 11:cancers11020142. [PMID: 30691003 PMCID: PMC6406545 DOI: 10.3390/cancers11020142] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/15/2019] [Accepted: 01/22/2019] [Indexed: 12/23/2022] Open
Abstract
Delta-like 4 (DLL4) is a pivotal endothelium specific Notch ligand that has been shown to function as a regulating factor during physiological and pathological angiogenesis. DLL4 functions as a negative regulator of angiogenic branching and sprouting. Interestingly, Dll4 is with Vegf-a one of the few examples of haplo-insufficiency, resulting in obvious vascular abnormalities and in embryonic lethality. These striking phenotypes are a proof of concept of the crucial role played by the bioavailability of VEGF and DLL4 during vessel patterning and that there must be a very fine-tuning of DLL4 expression level. However, to date the expression regulation of this factor was poorly studied. In this study, we showed that the DLL4 5′-UTR harbors an Internal Ribosomal Entry Site (IRES) that, in contrast to cap-dependent translation, was efficiently utilized in cells subjected to several stresses including hypoxia and endoplasmic reticulum stress (ER stress). We identified PERK, a kinase activated by ER stress, as the driver of DLL4 IRES-mediated translation, and hnRNP-A1 as an IRES-Trans-Acting Factor (ITAF) participating in the IRES-dependent translation of DLL4 during endoplasmic reticulum stress. The presence of a stress responsive internal ribosome entry site in the DLL4 msRNA suggests that the process of alternative translation initiation, by controlling the expression of this factor, could have a crucial role in the control of endothelial tip cell function.
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Affiliation(s)
- Manon Jaud
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
| | - Céline Philippe
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
| | - Loic Van Den Berghe
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
- Vectorology Plateform, Technological pole CRCT, F-31037 Toulouse, France.
| | - Christèle Ségura
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
- Vectorology Plateform, Technological pole CRCT, F-31037 Toulouse, France.
| | - Laurent Mazzolini
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
| | - Stéphane Pyronnet
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
| | - Henrik Laurell
- Inserm UMR1048, I2MC (Institut des Maladies Métaboliques et Cardiovasculaires), Toulouse, France.
| | - Christian Touriol
- Inserm UMR1037, CRCT (Cancer Research Center of Toulouse), CNRS ERL5294, Université Toulouse III Paul-Sabatier, F-31037 Toulouse, France.
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5
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Eisermann K, Fraizer G. The Androgen Receptor and VEGF: Mechanisms of Androgen-Regulated Angiogenesis in Prostate Cancer. Cancers (Basel) 2017; 9:E32. [PMID: 28394264 PMCID: PMC5406707 DOI: 10.3390/cancers9040032] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/25/2017] [Accepted: 04/04/2017] [Indexed: 02/06/2023] Open
Abstract
Prostate cancer progression is controlled by the androgen receptor and new blood vessel formation, or angiogenesis, which promotes metastatic prostate cancer growth. Angiogenesis is induced by elevated expression of vascular endothelial growth factor (VEGF). VEGF is regulated by many factors in the tumor microenvironment including lowered oxygen levels and elevated androgens. Here we review evidence delineating hormone mediated mechanisms of VEGF regulation, including novel interactions between the androgen receptor (AR), epigenetic and zinc-finger transcription factors, AR variants and the hypoxia factor, HIF-1. The relevance of describing the impact of both hormones and hypoxia on VEGF expression and angiogenesis is revealed in recent reports of clinical therapies targeting both VEGF and AR signaling pathways. A better understanding of the complexities of VEGF expression could lead to improved targeting and increased survival time for a subset of patients with metastatic castration-resistant prostate cancer.
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Affiliation(s)
- Kurtis Eisermann
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA.
| | - Gail Fraizer
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA.
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6
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Cao L, Weetall M, Bombard J, Qi H, Arasu T, Lennox W, Hedrick J, Sheedy J, Risher N, Brooks PC, Trifillis P, Trotta C, Moon YC, Babiak J, Almstead NG, Colacino JM, Davis TW, Peltz SW. Discovery of Novel Small Molecule Inhibitors of VEGF Expression in Tumor Cells Using a Cell-Based High Throughput Screening Platform. PLoS One 2016; 11:e0168366. [PMID: 27992500 PMCID: PMC5161367 DOI: 10.1371/journal.pone.0168366] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 11/30/2016] [Indexed: 01/04/2023] Open
Abstract
Current anti-VEGF (Vascular Endothelial Growth Factor A) therapies to treat various cancers indiscriminately block VEGF function in the patient resulting in the global loss of VEGF signaling which has been linked to dose-limiting toxicities as well as treatment failures due to acquired resistance. Accumulating evidence suggests that this resistance is at least partially due to increased production of compensatory tumor angiogenic factors/cytokines. VEGF protein production is differentially controlled depending on whether cells are in the normal “homeostatic” state or in a stressed state, such as hypoxia, by post-transcriptional regulation imparted by elements in the 5’ and 3’ untranslated regions (UTR) of the VEGF mRNA. Using the Gene Expression Modulation by Small molecules (GEMS™) phenotypic assay system, we performed a high throughput screen to identify low molecular weight compounds that target the VEGF mRNA UTR-mediated regulation of stress-induced VEGF production in tumor cells. We identified a number of compounds that potently and selectively reduce endogenous VEGF production under hypoxia in HeLa cells. Medicinal chemistry efforts improved the potency and pharmaceutical properties of one series of compounds resulting in the discovery of PTC-510 which inhibits hypoxia-induced VEGF expression in HeLa cells at low nanomolar concentration. In mouse xenograft studies, oral administration of PTC-510 results in marked reduction of intratumor VEGF production and single agent control of tumor growth without any evident toxicity. Here, we show that selective suppression of stress-induced VEGF production within tumor cells effectively controls tumor growth. Therefore, this approach may minimize the liabilities of current global anti-VEGF therapies.
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Affiliation(s)
- Liangxian Cao
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
- * E-mail:
| | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Jenelle Bombard
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Hongyan Qi
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Tamil Arasu
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - William Lennox
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Jean Hedrick
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Josephine Sheedy
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Nicole Risher
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Peter C. Brooks
- Maine Medical Center Research Institute, Center for Molecular Medicine, Scarborough, Maine, United States of America
| | - Panayiota Trifillis
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Christopher Trotta
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Young-Choon Moon
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - John Babiak
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Neil G. Almstead
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Joseph M. Colacino
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Thomas W. Davis
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
| | - Stuart W. Peltz
- PTC Therapeutics, Inc., South Plainfield, New Jersey, United States of America
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7
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Vaysse C, Philippe C, Martineau Y, Quelen C, Hieblot C, Renaud C, Nicaise Y, Desquesnes A, Pannese M, Filleron T, Escourrou G, Lawson M, Rintoul RC, Delisle MB, Pyronnet S, Brousset P, Prats H, Touriol C. Key contribution of eIF4H-mediated translational control in tumor promotion. Oncotarget 2016; 6:39924-40. [PMID: 26498689 PMCID: PMC4741870 DOI: 10.18632/oncotarget.5442] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/03/2015] [Indexed: 02/06/2023] Open
Abstract
Dysregulated expression of translation initiation factors has been associated with carcinogenesis, but underlying mechanisms remains to be fully understood. Here we show that eIF4H (eukaryotic translation initiation factor 4H), an activator of the RNA helicase eIF4A, is overexpressed in lung carcinomas and predictive of response to chemotherapy. In lung cancer cells, depletion of eIF4H enhances sensitization to chemotherapy, decreases cell migration and inhibits tumor growth in vivo, in association with reduced translation of mRNA encoding cell-proliferation (c-Myc, cyclin D1) angiogenic (FGF-2) and anti-apoptotic factors (CIAP-1, BCL-xL). Conversely, each isoform of eIF4H acts as an oncogene in NIH3T3 cells by stimulating transformation, invasion, tumor growth and resistance to drug-induced apoptosis together with increased translation of IRES-containing or structured 5′UTR mRNAs. These results demonstrate that eIF4H plays a crucial role in translational control and can promote cellular transformation by preferentially regulating the translation of potent growth and survival factor mRNAs, indicating that eIF4H is a promising new molecular target for cancer therapy.
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Affiliation(s)
- Charlotte Vaysse
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Céline Philippe
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Yvan Martineau
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Cathy Quelen
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Corinne Hieblot
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Claire Renaud
- Department of Thoracic Surgery, Rangueil-Larrey Hospital, Toulouse, France
| | - Yvan Nicaise
- Department of Pathology, CHU Rangueil, Toulouse, France
| | | | | | - Thomas Filleron
- Clinical Trial Office, Cellule Biostatistique Institut Universitaire du Cancer Toulouse, Toulouse, France
| | - Ghislaine Escourrou
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Department of Pathology, CHU Rangueil, Toulouse, France
| | - Malcolm Lawson
- Department of Respiratory Medicine, Broomfield Hospital, Chelmsford, Essex, UK
| | - Robert C Rintoul
- Department of Thoracic Oncology, Papworth Hospital, Cambridge, UK
| | - Marie Bernadette Delisle
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Department of Pathology, CHU Rangueil, Toulouse, France
| | - Stéphane Pyronnet
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Pierre Brousset
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France.,Department of Pathology, Institut Universitaire du Cancer, Toulouse, France
| | - Hervé Prats
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
| | - Christian Touriol
- INSERM U1037, CRCT, Cancer Research Center of Toulouse, Toulouse, France.,Toulouse University, Paul Sabatier, Toulouse, France
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8
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Weetall M, Davis T, Elfring G, Northcutt V, Cao L, Moon YC, Riebling P, Dali M, Hirawat S, Babiak J, Colacino J, Almstead N, Spiegel R, Peltz SW. Phase 1 Study of Safety, Tolerability, and Pharmacokinetics of PTC299, an Inhibitor of Stress-Regulated Protein Translation. Clin Pharmacol Drug Dev 2016; 5:296-305. [PMID: 27310330 PMCID: PMC5066743 DOI: 10.1002/cpdd.240] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 11/09/2015] [Indexed: 11/30/2022]
Abstract
PTC299 is a novel small molecule that specifically blocks the production of protein from selected mRNAs that under certain conditions use noncanonical ribosomal translational pathways. Hypoxia, oncogenic transformation, and viral infections limit normal translation and turn on these noncanonical translation pathways that are sensitive to PTC299. Vascular endothelial cell growth factor (VEGF) is an example of a transcript that is posttranscriptionally regulated. Single doses of PTC299 (0.03 to 3 mg/kg) were administered orally to healthy volunteers in a phase 1 single ascending‐dose study. In a subsequent multiple ascending‐dose study in healthy volunteers, multiple‐dose regimens (0.3 to 1.2 mg/kg twice a day or 1.6 mg/kg 3 times a day for 7 days) were evaluated. PTC299 was well tolerated in these studies. As expected in healthy volunteers, mean plasma VEGF levels did not change. Increases in Cmax and AUC of PTC299 were dose‐proportional. The target trough plasma concentration associated with preclinical efficacy was achieved within 7 days at doses of 0.6 mg/kg twice daily and above. These data demonstrate that PTC299 is orally bioavailable and well tolerated and support clinical evaluation of PTC299 in cancer, certain viral infections, or other diseases in which deregulation of translational control is a causal factor.
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Affiliation(s)
| | - Thomas Davis
- PTC Therapeutics, Inc, South Plainfield, NJ, USA
| | - Gary Elfring
- PTC Therapeutics, Inc, South Plainfield, NJ, USA
| | | | | | | | | | - Mandar Dali
- PTC Therapeutics, Inc, South Plainfield, NJ, USA
| | - Samit Hirawat
- Novartis Pharmaceuticals Corporation, Florham Park, NJ, USA
| | - John Babiak
- PTC Therapeutics, Inc, South Plainfield, NJ, USA
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9
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Cammas A, Dubrac A, Morel B, Lamaa A, Touriol C, Teulade-Fichou MP, Prats H, Millevoi S. Stabilization of the G-quadruplex at the VEGF IRES represses cap-independent translation. RNA Biol 2015; 12:320-9. [PMID: 25826664 DOI: 10.1080/15476286.2015.1017236] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The activation of translation contributes to malignant transformation and is an emerging target for cancer therapies. RNA G-quadruplex structures are general inhibitors of cap-dependent mRNA translation and were recently shown to be targeted for oncoprotein translational activation. In contrast however, the G-quadruplex within the 5'UTR of the human vascular endothelial growth factor A (VEGF) has been shown to be essential for IRES-mediated translation. Since VEGF has a pivotal role in tumor angiogenesis and is a major target of anti-tumoral therapies, we investigated the structure/function relationship of the VEGF G-quadruplex and defined whether it could have a therapeutic potential. We found that the G-quadruplex within the VEGF IRES is dispensable for cap-independent function and activation in stress conditions. However, stabilization of the VEGF G-quadruplex by increasing the G-stretches length or by replacing it with the one of NRAS results in strong inhibition of IRES-mediated translation of VEGF. We also demonstrate that G-quadruplex ligands stabilize the VEGF G-quadruplex and inhibit cap-independent translation in vitro. Importantly, the amount of human VEGF mRNA associated with polysomes decreases in the presence of a highly selective stabilizing G-quadruplex ligand, resulting in reduced VEGF protein expression. Together, our results uncover the existence of functionally silent G-quadruplex structures that are susceptible to conversion into efficient repressors of cap-independent mRNA translation. These findings have implications for the in vivo applications of G-quadruplex-targeting compounds and for anti-angiogenic therapies.
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Affiliation(s)
- Anne Cammas
- a Inserm UMR 1037- University of Toulouse III; Cancer Research Center of Toulouse (CRCT) ; Toulouse, France
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10
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Berendsen AD, Olsen BR. Regulation of adipogenesis and osteogenesis in mesenchymal stem cells by vascular endothelial growth factor A. J Intern Med 2015; 277:674-80. [PMID: 25779338 DOI: 10.1111/joim.12364] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the mechanisms by which bone marrow mesenchymal stem cells (BMSCs) differentiate into bone-forming osteoblasts and marrow adipocytes is crucial to develop strategies for the treatment of several bone diseases. Age-related bone loss resulting in osteopenia and osteoporosis has been associated with reduced numbers of osteoblasts and increased numbers of adipocytes, likely originating from differentiation defects in BMSCs. Although many factors involved in the complex regulation of osteoblast and adipocyte cell lineages have previously been identified, their functional interactions in the context of BMSC differentiation and maintenance of bone homeostasis during ageing are unknown. Recent discoveries have provided important new insights into the mechanisms by which the nuclear envelope protein lamin A and vascular endothelial growth factor A (VEGF) mutually control BMSC fate. Particularly interesting is the finding that VEGF in this context functions as an intracellular protein, unaffected by neutralizing antibodies, and not as a secreted growth factor. These insights may not only facilitate the identification of new targets for treating bone diseases but also lead to improved design of tissue engineering approaches aimed at stimulating bone regeneration and repair.
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Affiliation(s)
- A D Berendsen
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - B R Olsen
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
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11
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Godovac-Zimmermann J, Mulvey C, Konstantoulaki M, Sainsbury R, Brown LR. Promise of multiphoton detection in discovery and diagnostic proteomics. Expert Rev Proteomics 2014; 4:161-73. [PMID: 17425453 DOI: 10.1586/14789450.4.2.161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Proteomics has lacked adequate methods for handling the complexity (hundreds of thousands of different proteins) and range of protein concentrations (> or =10(6)) of eukaryotic proteomes. New multiphoton-detection methods for ultrasensitive detection of proteins produce 10,000-fold gains in sensitivity and allow highly quantitative, linear detection of 50 zmol (30,000 molecules) to 500 fmol of proteins in complex samples. The potential of multiphoton detection in top-down proteomics analyses is illustrated with applications in monitoring proteomes in very small numbers of cells, in identifying and monitoring complex functional isoforms of cancer-related proteins, and in super-sensitive immunoassays of serum proteins for high-performance detection of cancer.
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12
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Morfoisse F, Kuchnio A, Frainay C, Gomez-Brouchet A, Delisle MB, Marzi S, Helfer AC, Hantelys F, Pujol F, Guillermet-Guibert J, Bousquet C, Dewerchin M, Pyronnet S, Prats AC, Carmeliet P, Garmy-Susini B. Hypoxia induces VEGF-C expression in metastatic tumor cells via a HIF-1α-independent translation-mediated mechanism. Cell Rep 2014; 6:155-67. [PMID: 24388748 DOI: 10.1016/j.celrep.2013.12.011] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 10/28/2013] [Accepted: 12/06/2013] [Indexed: 01/04/2023] Open
Abstract
Various tumors metastasize via lymph vessels and lymph nodes to distant organs. Even though tumors are hypoxic, the mechanisms of how hypoxia regulates lymphangiogenesis remain poorly characterized. Here, we show that hypoxia reduced vascular endothelial growth factor C (VEGF-C) transcription and cap-dependent translation via the upregulation of hypophosphorylated 4E-binding protein 1 (4E-BP1). However, initiation of VEGF-C translation was induced by hypoxia through an internal ribosome entry site (IRES)-dependent mechanism. IRES-dependent VEGF-C translation was independent of hypoxia-inducible factor 1α (HIF-1α) signaling. Notably, the VEGF-C IRES activity was higher in metastasizing tumor cells in lymph nodes than in primary tumors, most likely because lymph vessels in these lymph nodes were severely hypoxic. Overall, this transcription-independent but translation-dependent upregulation of VEGF-C in hypoxia stimulates lymphangiogenesis in tumors and lymph nodes and may contribute to lymphatic metastasis.
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Affiliation(s)
- Florent Morfoisse
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | - Anna Kuchnio
- Vesalius Research Center, VIB, University of Leuven, 3000 Leuven, Belgium
| | - Clement Frainay
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | - Anne Gomez-Brouchet
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | - Marie-Bernadette Delisle
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | - Stefano Marzi
- UPR 9002 CNRS-ARN, Université De Strasbourg, IBMC, 67084 Strasbourg, France
| | | | - Fransky Hantelys
- Université de Toulouse, UPS, TRADGENE, EA4554, 31432 Toulouse, France
| | - Francoise Pujol
- Université de Toulouse, UPS, TRADGENE, EA4554, 31432 Toulouse, France
| | - Julie Guillermet-Guibert
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | - Corinne Bousquet
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | - Mieke Dewerchin
- Vesalius Research Center, VIB, University of Leuven, 3000 Leuven, Belgium
| | - Stephane Pyronnet
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France
| | | | - Peter Carmeliet
- Vesalius Research Center, VIB, University of Leuven, 3000 Leuven, Belgium
| | - Barbara Garmy-Susini
- Inserm, U1037, 31432 Toulouse, France; Université de Toulouse, UPS, Cancer Research Center of Toulouse, Equipe Labellisee Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer, 31432 Toulouse, France.
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13
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Fátima LA, Evangelista MC, Silva RS, Cardoso APM, Baruselli PS, Papa PC. FSH up-regulates angiogenic factors in luteal cells of buffaloes. Domest Anim Endocrinol 2013; 45:224-37. [PMID: 24209507 DOI: 10.1016/j.domaniend.2013.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 09/11/2013] [Accepted: 09/12/2013] [Indexed: 02/05/2023]
Abstract
Follicle-stimulating hormone has been widely used to induce superovulation in buffaloes and cows and usually triggers functional and morphologic alterations in the corpus luteum (CL). Several studies have shown that FSH is involved in regulating vascular development and that adequate angiogenesis is essential for normal luteal development. Angiogenesis is regulated by many growth factors, of which vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) have an established central role. Therefore, we have used a combination of in vitro and in vivo studies to assess the effects of FSH on the expression of VEGF and FGF2 and their receptors in buffalo luteal cells. The in vivo model consisted of 12 buffalo cows, divided into control (n = 6) and superovulated (n = 6) groups, and CL samples were collected on day 6 after ovulation. In this model, we analyzed the gene and protein expression of FGF2 and its receptors and the protein expression of VEGFA systems with the use of real-time PCR, Western blot analysis, and immunohistochemistry. In the in vitro model, granulosa cells were collected from small follicles (diameter, 4-6 mm) of buffaloes and cultured for 4 d in serum-free medium with or without FSH (10 ng/mL). To induce in vitro luteinization, LH (250 ng/mL) and fetal bovine serum (10%) were added to the medium, and granulosa cells were maintained in culture for 4 d more. The progesterone concentration in the medium was measured at days 4, 5, and 8 after the beginning of cell culture. Cells were collected at day 8 and subjected to real-time PCR, Western blot analysis, and immunofluorescence for assessment of the expression of FGF2, VEGF, and their receptors. To address the percentage of steroidogenic and growth factor-expressing cells in the culture, flow cytometry was performed. We observed that in superovulated buffalo CL, the FGF2 system mRNA expression was decreased even as protein expression was increased and that the VEGF protein was increased (P < 0.05). In vitro experiments with granulosa cells showed an increase in the mRNA expression of VEGF and FGF2 and its receptors 1 and 2 and protein expression of VEGF, kinase insert domain receptor, FGF receptor 2, and FGF receptor 3 in cells treated with FSH (P < 0.05), in contrast to the in vivo experiments. Moreover, the progesterone production by FSH-treated cells was elevated compared with untreated cells (P < 0.05). Our findings indicate that VEGF, FGF2, and their receptors were differentially regulated by FSH in vitro and in vivo in buffalo luteal cells, which points toward a role of CL environment in modulating cellular answers to gonadotropins.
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MESH Headings
- Angiogenic Proteins/analysis
- Angiogenic Proteins/genetics
- Animals
- Buffaloes/metabolism
- Cells, Cultured
- Female
- Fibroblast Growth Factor 2/analysis
- Fibroblast Growth Factor 2/genetics
- Fluorescent Antibody Technique
- Follicle Stimulating Hormone/pharmacology
- Granulosa Cells/chemistry
- Granulosa Cells/drug effects
- Granulosa Cells/metabolism
- Luteal Cells/chemistry
- Luteal Cells/metabolism
- Luteinizing Hormone/pharmacology
- Male
- Progesterone/biosynthesis
- RNA, Messenger/analysis
- Real-Time Polymerase Chain Reaction/veterinary
- Receptor, Fibroblast Growth Factor, Type 2/analysis
- Receptor, Fibroblast Growth Factor, Type 2/genetics
- Receptor, Fibroblast Growth Factor, Type 3/analysis
- Receptor, Fibroblast Growth Factor, Type 3/genetics
- Superovulation/physiology
- Up-Regulation
- Vascular Endothelial Growth Factor A/analysis
- Vascular Endothelial Growth Factor A/genetics
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Affiliation(s)
- L A Fátima
- Department of Surgery, Sector of Anatomy, Faculty of Veterinary Medicine and Animal Sciences, University of São Paulo, Av. Prof. Dr Orlando Marques Paiva, 87, São Paulo, SP, 05508-270, Brazil.
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14
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Arcondéguy T, Lacazette E, Millevoi S, Prats H, Touriol C. VEGF-A mRNA processing, stability and translation: a paradigm for intricate regulation of gene expression at the post-transcriptional level. Nucleic Acids Res 2013; 41:7997-8010. [PMID: 23851566 PMCID: PMC3783158 DOI: 10.1093/nar/gkt539] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Vascular Endothelial Growth Factor A (VEGF-A) is a potent secreted mitogen crucial for physiological and pathological angiogenesis. Post-transcriptional regulation of VEGF-A occurs at multiple levels. Firstly, alternative splicing gives rise to different transcript variants encoding diverse isoforms that exhibit distinct biological properties with regard to receptor binding and extra-cellular localization. Secondly, VEGF-A mRNA stability is regulated by effectors such as hypoxia or growth factors through the binding of stabilizing and destabilizing proteins at AU-rich elements located in the 3′-untranslated region. Thirdly, translation of VEGF-A mRNA is a controlled process involving alternative initiation codons, internal ribosome entry sites (IRESs), an upstream open reading frame (uORF), miRNA targeting and a riboswitch in the 3′ untranslated region. These different levels of regulation cooperate for the crucial fine-tuning of the expression of VEGF-A variants. This review will be focused on our current knowledge of the complex post-transcriptional regulatory switches that modulate the cellular VEGF-A level, a paradigmatic model of post-transcriptional regulation.
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Affiliation(s)
- Tania Arcondéguy
- Inserm UMR1037, Centre de Recherches en Cancérologie de Toulouse, CHU Rangueil, BP84225, 31432 Toulouse Cedex 4, France and Université Toulouse III Paul-Sabatier, 118 Route de Narbonne, 31400 Toulouse, France
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15
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Bentmann E, Haass C, Dormann D. Stress granules in neurodegeneration - lessons learnt from TAR DNA binding protein of 43 kDa and fused in sarcoma. FEBS J 2013; 280:4348-70. [DOI: 10.1111/febs.12287] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/28/2013] [Accepted: 04/08/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Eva Bentmann
- Adolf Butenandt Institute; Department of Biochemistry; Ludwig Maximilians University; Munich Germany
| | - Christian Haass
- Adolf Butenandt Institute; Department of Biochemistry; Ludwig Maximilians University; Munich Germany
- German Center for Neurodegenerative Diseases (DZNE); Munich Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich Germany
| | - Dorothee Dormann
- Adolf Butenandt Institute; Department of Biochemistry; Ludwig Maximilians University; Munich Germany
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16
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Jewer M, Findlay SD, Postovit LM. Post-transcriptional regulation in cancer progression : Microenvironmental control of alternative splicing and translation. J Cell Commun Signal 2012; 6:233-48. [PMID: 23054595 DOI: 10.1007/s12079-012-0179-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 09/24/2012] [Indexed: 12/28/2022] Open
Abstract
The microenvironment acts as a conduit for cellular communication, delivering signals that direct development and sustain tissue homeostasis. In pathologies such as cancer, this integral function of the microenvironment is hijacked to support tumor growth and progression. Cells sense the microenvironment via signal transduction pathways culminating in altered gene expression. In addition to induced transcriptional changes, the microenvironment exerts its effect on the cell through regulation of post-transcriptional processes including alternative splicing and translational control. Here we describe how alternative splicing and protein translation are controlled by microenvironmental parameters such as oxygen availability. We also emphasize how these pathways can be utilized to support processes that are hallmarks of cancer such as angiogenesis, proliferation, and cell migration. We stress that cancer cells respond to their microenvironment through an integrated regulation of gene expression at multiple levels that collectively contribute to disease progression.
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Affiliation(s)
- Michael Jewer
- Department of Anatomy & Cell Biology, The Schulich School of Medicine and Dentistry, Western University, 438 Medical Science Building, London, ON, N6A 5C1, Canada
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17
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Kamp MA, Shakeri B, Tevoufouet EE, Krieger A, Henry M, Behnke K, Herzig S, Hescheler J, Radhakrishnan K, Parent L, Schneider T. The C-terminus of human Ca(v)2.3 voltage-gated calcium channel interacts with alternatively spliced calmodulin-2 expressed in two human cell lines. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1045-57. [PMID: 22633975 DOI: 10.1016/j.bbapap.2012.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/27/2012] [Accepted: 05/16/2012] [Indexed: 01/20/2023]
Abstract
Ca(v)2.3 containing voltage-activated Ca(2+) channels are expressed in excitable cells and trigger neurotransmitter and peptide-hormone release. Their expression remote from the fast release sites leads to the accumulation of presynaptic Ca(2+) which can both, facilitate and inhibit the influx of Ca(2+) ions through Ca(v)2.3. The facilitated Ca(2+) influx was recently related to hippocampal postsynaptic facilitation and long term potentiation. To analyze Ca(2+) mediated modulation of cellular processes more in detail, protein partners of the carboxy terminal tail of Ca(v)2.3 were identified by yeast-2-hybrid screening, leading in two human cell lines to the detection of a novel, extended and rarely occurring splice variant of calmodulin-2 (CaM-2), called CaM-2-extended (CaM-2-ext). CaM-2-ext interacts biochemically with the C-terminus of Ca(v)2.3 similar to the classical CaM-2 as shown by co-immunoprecipitation. Functionally, only CaM-2-ext reduces whole cell inward currents significantly. The insertion of the novel 46 nts long exon and the consecutive expression of CaM-2-ext must be dependent on a new upstream translation initiation site which is only rarely used in the tested human cell lines. The structure of the N-terminal extension is predicted to be more hydrophobic than the remaining CaM-2-ext protein, suggesting that it may help to dock it to the lipophilic membrane surrounding.
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Affiliation(s)
- Marcel A Kamp
- Institute for Neurophysiology, University of Cologne, Germany
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18
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Hanson PJ, Zhang HM, Hemida MG, Ye X, Qiu Y, Yang D. IRES-Dependent Translational Control during Virus-Induced Endoplasmic Reticulum Stress and Apoptosis. Front Microbiol 2012; 3:92. [PMID: 22461781 PMCID: PMC3307021 DOI: 10.3389/fmicb.2012.00092] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 02/23/2012] [Indexed: 12/11/2022] Open
Abstract
Many virus infections and stresses can induce endoplasmic reticulum (ER) stress response, a host self-defense mechanism against viral invasion and stress. During this event, viral and cellular gene expression is actively regulated and often encounters a switching of the translation initiation from cap-dependent to internal ribosome-entry sites (IRES)-dependent. This switching is largely dependent on the mRNA structure of the 5′ untranslated region (5′ UTR) and on the particular stress stimuli. Picornaviruses and some other viruses contain IRESs within their 5′ UTR of viral genome and employ an IRES-driven mechanism for translation initiation. Recently, a growing number of cellular genes involved in growth control, cell cycle progression and apoptosis were also found to contain one or more IRES within their long highly structured 5′ UTRs. These genes initiate translation usually by a cap-dependent mechanism under normal physiological conditions; however, in certain environments, such as infection, starvation, and heat shock they shift translation initiation to an IRES-dependent modality. Although the molecular mechanism is not entirely understood, a number of studies have revealed that several cellular biochemical processes are responsible for the switching of translation initiation to IRES-dependent. These include the cleavage of translation initiation factors by viral and/or host proteases, phosphorylation (inactivation) of host factors for translation initiation, overproduction of homologous proteins of cap-binding protein eukaryotic initiation factors (eIF)4E, suppression of cap-binding protein eIF4E expression by specific microRNA, activation of enzymes for mRNA decapping, as well as others. Here, we summarize the recent advances in our understanding of the molecular mechanisms for the switching of translation initiation, particularly for the proteins involved in cell survival and apoptosis in the ER stress pathways during viral infections.
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Affiliation(s)
- Paul J Hanson
- Department of Pathology and Laboratory Medicine, The Institute for Heart and Lung Health, St. Paul's Hospital, University of British Columbia Vancouver, BC, Canada
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19
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Griseri P, Bourcier C, Hieblot C, Essafi-Benkhadir K, Chamorey E, Touriol C, Pagès G. A synonymous polymorphism of the Tristetraprolin (TTP) gene, an AU-rich mRNA-binding protein, affects translation efficiency and response to Herceptin treatment in breast cancer patients. Hum Mol Genet 2011; 20:4556-68. [PMID: 21875902 DOI: 10.1093/hmg/ddr390] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Post-transcriptional regulation plays a central role in cell differentiation and proliferation. Among the regulatory factors involved in this mechanism, Tristetraprolin (ZFP36 or TTP) is the prototype of a family of RNA-binding proteins that bind to adenylate and uridylate (AU)-rich sequences in the 3'UTR of mRNAs, which promotes their physiological decay. Here, we investigated whether TTP correlates with tumor aggressiveness in breast cancer and is a novel prognostic factor for this neoplasia. By immunoblot analysis, we determined the amount of TTP protein in different breast cancer cell lines and found an inverse correlation between aggressiveness and metastatic potential. TTP mRNA levels were very variable among cells lines and did not correlate with protein levels. Interestingly, by sequencing the entire TTP coding region in Hs578T cells that do not express the TTP protein, we identified a synonymous polymorphism (rs3746083) that showed a statistically significant association with a lack of response to Herceptin/Trastuzumab in HER2-positive-breast cancer patients. Even though this genetic change did not modify the corresponding amino acid, we performed functional studies and showed an effect on protein translation associated with the variant allele with respect to the wild-type. These data underline the importance of synonymous variants on gene expression and the potential role of TTP genetic polymorphisms as a prognostic marker for breast cancer.
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Affiliation(s)
- Paola Griseri
- University Nice-Sophia Antipolis Institute of Developmental Biology and Cancer, CNRS UMR 6543, France
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20
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Xue Y, Li NL, Yang JY, Chen Y, Yang LL, Liu WC. Phosphatidylinositol 3′-kinase signaling pathway is essential for Rac1-induced hypoxia-inducible factor-1α and vascular endothelial growth factor expression. Am J Physiol Heart Circ Physiol 2011; 300:H2169-76. [DOI: 10.1152/ajpheart.00970.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated the roles of RhoA, Rac1, and Cdc42 in hypoxia-driven angiogenesis. However, the role of oncogenes in hypoxia signaling is poorly understood. Given the importance of Rho proteins in the hypoxic response, we hypothesized that Rho family members could act as mediators of hypoxic signal transduction. We investigated the cross-talk between hypoxia and oncogene-driven signal transduction pathways and explored the role of Rac1 on hypoxia-induced hypoxia-inducible factor (HIF)-1α and VEGF expression. Since the phosphatidylinositol 3′-kinase (PI3K) pathway is involved in signal transduction of many oncogenes, we explored the role of PI3K on Rac1-mediated expression of HIF-1α and VEGF in hypoxia. We showed that LY-294002, a PI3K inhibitor, suppressed HIF-1α and VEGF induction under hypoxic conditions by up to 50%. Activation of Rac1 resulted in an upregulation of hypoxia-induced HIF-1α expression, which was blocked by LY-294002. These data suggested that Rac1 is an intermediate in the PI3K-mediated induction of HIF-1α. Interestingly, there was a significant downregulation of the tumor suppressor genes p53 and von Hippel-Lindau tumor suppressor (VHL) in cells expressing a constitutively active form of Rac1. Rac1-mediated inhibition of p53 and VHL could therefore be implicated in the upregulation of HIF-1α expression.
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Affiliation(s)
- Yan Xue
- Departments of 1Clinical Oncology and
| | - Nan-Lin Li
- Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | | | - Yan Chen
- Departments of 1Clinical Oncology and
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21
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Beerman RW, Jongens TA. A non-canonical start codon in the Drosophila fragile X gene yields two functional isoforms. Neuroscience 2011; 181:48-66. [PMID: 21333716 DOI: 10.1016/j.neuroscience.2011.02.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 02/10/2011] [Accepted: 02/12/2011] [Indexed: 02/07/2023]
Abstract
Fragile X syndrome is caused by the loss of expression of the fragile X mental retardation protein (FMRP). As a RNA binding protein, FMRP functions in translational regulation, localization, and stability of its neuronal target transcripts. The Drosophila homologue, dFMR1, is well conserved in sequence and function with respect to human FMRP. Although dFMR1 is known to express two main isoforms, the mechanism behind production of the second, more slowly migrating isoform has remained elusive. Furthermore, it remains unknown whether the two isoforms may also contribute differentially to dFMR1 function. We have found that this second dFMR1 isoform is generated through an alternative translational start site in the dfmr1 5'UTR. This 5'UTR coding sequence is well conserved in the melanogaster group. Translation of the predominant, smaller form of dFMR1 (dFMR1-S(N)) begins at a canonical start codon (ATG), whereas translation of the minor, larger form (dFMR1-L(N)) begins upstream at a non-canonical start codon (CTG). To assess the contribution of the N-terminal extension toward dFMR1 activity, we generated transgenic flies that exclusively express either dFMR1-S(N) or dFMR1-L(N). Expression analyses throughout development revealed that dFMR1-S(N) is required for normal dFMR1-L(N) expression levels in adult brains. In situ expression analyses showed that either dFMR1-S(N) or dFMR1-L(N) is individually sufficient for proper dFMR1 localization in the nervous system. Functional studies demonstrated that both dFMR1-S(N) and dFMR1-L(N) can function independently to rescue dfmr1 null defects in synaptogenesis and axon guidance. Thus, dfmr1 encodes two functional isoforms with respect to expression and activity throughout neuronal development.
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Affiliation(s)
- R W Beerman
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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22
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Spriggs KA, Bushell M, Willis AE. Translational regulation of gene expression during conditions of cell stress. Mol Cell 2010; 40:228-37. [PMID: 20965418 DOI: 10.1016/j.molcel.2010.09.028] [Citation(s) in RCA: 523] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 09/10/2010] [Accepted: 09/28/2010] [Indexed: 01/17/2023]
Abstract
A number of stresses, including nutrient stress, temperature shock, DNA damage, and hypoxia, can lead to changes in gene expression patterns caused by a general shutdown and reprogramming of protein synthesis. Each of these stress conditions results in selective recruitment of ribosomes to mRNAs whose protein products are required for responding to stress. This recruitment is regulated by elements within the 5' and 3' untranslated regions of mRNAs, including internal ribosome entry segments, upstream open reading frames, and microRNA target sites. These elements can act singly or in combination and are themselves regulated by trans-acting factors. Translational reprogramming can result in increased life span, and conversely, deregulation of these translation pathways is associated with disease including cancer and diabetes.
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Affiliation(s)
- Keith A Spriggs
- Centre for Biomolecular Sciences, School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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23
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Morris MJ, Negishi Y, Pazsint C, Schonhoft JD, Basu S. An RNA G-quadruplex is essential for cap-independent translation initiation in human VEGF IRES. J Am Chem Soc 2010; 132:17831-9. [PMID: 21105704 DOI: 10.1021/ja106287x] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RNA G-quadruplexes located within the 5'-UTR of mRNA are almost always known to be associated with repression of cap-dependent translation. However, in this report we present functional as well as structural evidence that sequence redundancy in a G-rich segment within the 5'-UTR of human VEGF mRNA supports a 'switchable' RNA G-quadruplex structure that is essential for IRES-mediated translation initiation. Additionally, utilization of a specific combination of G-tracts within this segment allows for the conformational switch that implies a tunable regulatory role of the quadruplex structure in translation initiation. A sequence engineered from a functionally handicapped mutant moderately rescued the activity, further indicating the importance of G-quadruplex structure for VEGF IRES-A function. This to our knowledge is the first report of a conformationally flexible RNA G-quadruplex which is essential for IRES-mediated translation initiation.
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Affiliation(s)
- Mark J Morris
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
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24
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Chruściel M, Zięcik AJ, Andronowska A. Expression of the vascular endothelial growth factor (VEGF-A) and its receptors in the umbilical cord in the course of pregnancy in the pig. Reprod Domest Anim 2010; 46:434-43. [PMID: 20825582 DOI: 10.1111/j.1439-0531.2010.01686.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The umbilical cord (UC) and the placenta are important organs through which respiratory gases, nutrients, wastes and biologically active substances are exchanged between the maternal and the foetal system. A rapid placental vascularization observed in the second half of pig pregnancy is positively correlated with the mRNA expression of the vascular endothelial growth factor (VEGF). Based on these findings, we hypothesized that VEGF may have a stimulatory effect in the dynamically growing UC. To further understand the role of the VEGF-VEGFR system during UC development, mRNA and protein expression as well as the cellular localization of VEGF-A, VEGFR-1 and VEGFR-2 in UC were examined on days 40, 60, 75 and 90 of pregnancy and after physiological delivery in the pig (day 114 of pregnancy). Real Time RT-PCR analysis showed an increase in the mRNA levels of VEGF120 and VEGF164 from day 90 of pregnancy. VEGFR-1 mRNA expression was significantly increased on day 75 of pregnancy. No significant changes in VEGFR-2 mRNA expression were detected. In turn, western blot analysis revealed an increase in VEGF-A protein expression on day 40, compared to the later days of pregnancy. A rapid increase in the VEGFR-1 protein level was noted on day 75 and 90 of gestation. No significant changes in VEGFR-2 protein expression were detected on any of the analysed days of pregnancy. Immunohistochemical staining enabled detection of VEGF-VEGFR system, in endothelial and tunica media cells of the umbilical vessels and in allantoic duct and amniotic epithelium on all analysed days of pregnancy. Positive reactions for VEGF-A and VEGFR-1, but not VEGFR-2, were also observed in myofibroblasts. In conclusion, this data shows that members of the VEGF-VEGFR system are temporally and spatially well localized for playing key roles during umbilical cord formation and its intensive growth observed after day 75 of pregnancy.
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Affiliation(s)
- M Chruściel
- Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Olsztyn, Poland
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Schrufer TL, Antonetti DA, Sonenberg N, Kimball SR, Gardner TW, Jefferson LS. Ablation of 4E-BP1/2 prevents hyperglycemia-mediated induction of VEGF expression in the rodent retina and in Muller cells in culture. Diabetes 2010; 59:2107-16. [PMID: 20547975 PMCID: PMC2927931 DOI: 10.2337/db10-0148] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Vascular endothelial growth factor (VEGF) contributes to diabetic retinopathy, but control of its expression is not well understood. Here, we tested the hypothesis that hyperglycemia mediates induction of VEGF expression in a eukaryotic initiation factor 4E (eIF4E) binding protein (4E-BP) 1 and 2 dependent manner. RESEARCH DESIGN AND METHODS The retina was harvested from control and type 1 diabetic rats and mice and analyzed for VEGF mRNA and protein expression as well as biomarkers of translational control mechanisms. Similar analyses were performed in Müller cell cultures exposed to hyperglycemic conditions. The effect of 4E-BP1 and 4E-BP2 gene deletion on VEGF expression was examined in mice and in mouse embryo fibroblasts (MEFs). RESULTS Whereas VEGF mRNA in the retina remained constant, VEGF expression was increased as early as 2 weeks after the onset of diabetes. Increases in expression of 4E-BP1 protein mirrored those of VEGF and expression of 4E-BP1 mRNA was unchanged. Similar results were observed after 10 h of exposure of cells in culture to hyperglycemic conditions. Importantly, the diabetes-induced increase in VEGF expression was not observed in mice deficient in 4E-BP1 and 4E-BP2, nor in MEFs lacking the two proteins. CONCLUSIONS Hyperglycemia induces VEGF expression through cap-independent mRNA translation mediated by increased expression of 4E-BP1. Because the VEGF mRNA contains two internal ribosome entry sites, the increased expression is likely a consequence of ribosome loading at these sites. These findings provide new insights into potential targets for treatment of diabetic retinopathy.
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Affiliation(s)
- Tabitha L. Schrufer
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - David A. Antonetti
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Nahum Sonenberg
- Department of Biochemistry, McIntyre Medical Science Bldg., Montreal, Quebec, Canada
| | - Scot R. Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
- Corresponding author: Scot R. Kimball,
| | - Thomas W. Gardner
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
- Department of Ophthalmology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Leonard S. Jefferson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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Kawagishi H, Nakamura H, Maruyama M, Mizutani S, Sugimoto K, Takagi M, Sugimoto M. ARF suppresses tumor angiogenesis through translational control of VEGFA mRNA. Cancer Res 2010; 70:4749-58. [PMID: 20501856 DOI: 10.1158/0008-5472.can-10-0368] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular endothelial growth factor A (VEGFA) is a specific mitogen for vascular endothelial cells that plays a critical role in cancer neoangiogenesis. Here, we report that the nucleolar tumor suppressor p19(ARF) suppresses VEGFA expression, acting at the level of mRNA translation without affecting the transcription of the VEGFA gene. Translational repression of VEGFA mRNA by p19(ARF) does not require p53, a major target of the ARF tumor suppressor pathway, but instead correlates with binding to nucleophosmin/B23. Maintaining VEGFA expression relies on nucleophosmin/B23, and downregulating this protein by RNAi or p19(ARF) leads to translational repression of VEGFA. p19(ARF) inhibits VEGFA-dependent tumor angiogenesis in nude mice. Additionally, p14(ARF) expression and microvessel density are inversely correlated in human colon carcinomas. Taken together, our results define a mechanism by which the ARF tumor suppressor targets the translational repression of specific oncogenes during neoplastic transformation.
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Affiliation(s)
- Hiroyuki Kawagishi
- Department of Mechanism of Aging, National Center for Geriatrics and Gerontology, Aichi, Japan.
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27
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Fallot S, Ben Naya R, Hieblot C, Mondon P, Lacazette E, Bouayadi K, Kharrat A, Touriol C, Prats H. Alternative-splicing-based bicistronic vectors for ratio-controlled protein expression and application to recombinant antibody production. Nucleic Acids Res 2009; 37:e134. [PMID: 19729510 PMCID: PMC2777421 DOI: 10.1093/nar/gkp716] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In the last decade polycistronic vectors have become essential tools for both basic science and gene therapy applications. In order to co-express heterologous polypeptides, different systems have been developed from Internal Ribosome Entry Site (IRES) based vectors to the use of the 2A peptide. Unfortunately, these methods are not fully suitable for the efficient and reproducible modulation of the ratio between the proteins of interest. Here we describe a novel bicistronic vector type based on the use of alternative splicing. By modifying the consensus sequence that governs splicing, we demonstrate that the ratio between the synthesized proteins could easily vary from 1 : 10 to 10 : 1. We have established this system with luciferase genes and we extended its application to the production of recombinant monoclonal antibodies. We have shown that these vectors could be used in several typical cell lines with similar efficiencies. We also present an adaptation of these vectors to hybrid alternative splicing/IRES constructs that allow a ratio-controlled expression of proteins of interest in stably transfected cell lines.
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Affiliation(s)
- Stéphanie Fallot
- Institut National de la Santé et de la Recherche Médicale, U858, CHU Rangueil, BP 84225, 31432 Toulouse cedex 4, France
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Ruiz de Almodovar C, Lambrechts D, Mazzone M, Carmeliet P. Role and therapeutic potential of VEGF in the nervous system. Physiol Rev 2009; 89:607-48. [PMID: 19342615 DOI: 10.1152/physrev.00031.2008] [Citation(s) in RCA: 334] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The development of the nervous and vascular systems constitutes primary events in the evolution of the animal kingdom; the former provides electrical stimuli and coordination, while the latter supplies oxygen and nutrients. Both systems have more in common than originally anticipated. Perhaps the most striking observation is that angiogenic factors, when deregulated, contribute to various neurological disorders, such as neurodegeneration, and might be useful for the treatment of some of these pathologies. The prototypic example of this cross-talk between nerves and vessels is the vascular endothelial growth factor or VEGF. Although originally described as a key angiogenic factor, it is now well established that VEGF also plays a crucial role in the nervous system. We describe the molecular properties of VEGF and its receptors and review the current knowledge of its different functions and therapeutic potential in the nervous system during development, health, disease and in medicine.
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Karaa ZS, Iacovoni JS, Bastide A, Lacazette E, Touriol C, Prats H. The VEGF IRESes are differentially susceptible to translation inhibition by miR-16. RNA (NEW YORK, N.Y.) 2009; 15:249-54. [PMID: 19144909 PMCID: PMC2648711 DOI: 10.1261/rna.1301109] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Experiments with EMCV (Encephalomyocarditis virus) internal ribosome entry sites (IRESes) have shown that microRNAs (miRs) are unable to inhibit IRES driven translation. However, it is accepted that miRs can inhibit translation through multiple mechanisms, only some of which require interaction with the 5' cap structure. In this report, we first validate the targeting of miR-16 to a predicted binding site in the VEGF 3'UTR. We developed a series of experiments to ascertain whether or not miR-16 can inhibit translation of transcripts driven by either of the VEGF IRESes. Our results indicate that cellular IRESes can be classified as both sensitive and insensitive to miR control. While VEGF IRES-A activity was not altered by miR-16 targeting to the 3'UTR, IRES-B was susceptible to miR-16 inhibition. Taken together with previous results that show that IRES-B selectively translates the CUG initiated VEGF-121 isoform, we can conclude that the existence of two differentially susceptible IRESes in the VEGF 5'UTR leads to even more complex regulatory control of VEGF isoform production. This study demonstrates for the first time the inhibition of cellular IRES driven translation by a miR.
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Affiliation(s)
- Zeïneb S Karaa
- Institut National de la Santé et de la Recherche Médicale, Toulouse, France
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Faure C, Linossier MT, Malaval L, Lafage-Proust MH, Peyroche S, Vico L, Guignandon A. Mechanical signals modulated vascular endothelial growth factor-A (VEGF-A) alternative splicing in osteoblastic cells through actin polymerisation. Bone 2008; 42:1092-101. [PMID: 18374641 DOI: 10.1016/j.bone.2008.02.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 02/05/2008] [Accepted: 02/09/2008] [Indexed: 01/10/2023]
Abstract
Since VEGF-A is involved in mechanically induced bone gain and because vegf exists under 6 isoforms exerting various biological effects, we studied vegf isoform expression and VEGF protein production in osteoblastic cells (rat Ros17/2.8 and human osteoblasts) submitted to 4 mechanical regimens. Mechanical regimens (1% stretch deformation) were designed with a fixed number of cycles (450) delivered at various frequencies (0.05 to 5 Hz). We found a negative correlation (R(2)=0.76, p<0.0001) between production of soluble VEGF and mechanical stretch frequency and a positive correlation (R(2)=0.99, p<0.0001) between production of matrix-bound VEGF and mechanical stretch frequency. mRNA expressions of soluble VEGF isoforms (121, 165) were specifically expressed under low frequency while matrix-bound VEGF isoforms (206, 189, 165, 145) were specifically expressed under high frequency in human osteoblasts. As f-actin stress fiber formation was significantly increased selectively in high frequency conditions, we disrupted actin fibers in Ros17/2.8 and found that immobilisation of VEGF was abolished. Conversely, Jasplakinolide treatment which increases stress fiber formation was able to mimic high frequency stretch-induced immobilisation of VEGF. Thus, we speculate that the stretch-induced increase in cell tension is responsible for matrix-bound vegf isoform production. Mechanically induced selection of soluble or matrix-bound VEGF production may modify osteoblast and endothelial cell crosstalk crucial during osteogenesis and fracture healing.
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Penn JS, Madan A, Caldwell RB, Bartoli M, Caldwell RW, Hartnett ME. Vascular endothelial growth factor in eye disease. Prog Retin Eye Res 2008; 27:331-71. [PMID: 18653375 DOI: 10.1016/j.preteyeres.2008.05.001] [Citation(s) in RCA: 519] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Collectively, angiogenic ocular conditions represent the leading cause of irreversible vision loss in developed countries. In the US, for example, retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration are the principal causes of blindness in the infant, working age and elderly populations, respectively. Evidence suggests that vascular endothelial growth factor (VEGF), a 40kDa dimeric glycoprotein, promotes angiogenesis in each of these conditions, making it a highly significant therapeutic target. However, VEGF is pleiotropic, affecting a broad spectrum of endothelial, neuronal and glial behaviors, and confounding the validity of anti-VEGF strategies, particularly under chronic disease conditions. In fact, among other functions VEGF can influence cell proliferation, cell migration, proteolysis, cell survival and vessel permeability in a wide variety of biological contexts. This article will describe the roles played by VEGF in the pathogenesis of retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration. The potential disadvantages of inhibiting VEGF will be discussed, as will the rationales for targeting other VEGF-related modulators of angiogenesis.
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Affiliation(s)
- J S Penn
- Vanderbilt University School of Medicine, Nashville, TN, USA.
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Masuda K, Teshima-Kondo S, Mukaijo M, Yamagishi N, Nishikawa Y, Nishida K, Kawai T, Rokutan K. A novel tumor-promoting function residing in the 5' non-coding region of vascular endothelial growth factor mRNA. PLoS Med 2008; 5:e94. [PMID: 18494554 PMCID: PMC2386836 DOI: 10.1371/journal.pmed.0050094] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Accepted: 03/13/2008] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Vascular endothelial growth factor-A (VEGF) is one of the key regulators of tumor development, hence it is considered to be an important therapeutic target for cancer treatment. However, clinical trials have suggested that anti-VEGF monotherapy was less effective than standard chemotherapy. On the basis of the evidence, we hypothesized that vegf mRNA may have unrecognized function(s) in cancer cells. METHODS AND FINDINGS Knockdown of VEGF with vegf-targeting small-interfering (si) RNAs increased susceptibility of human colon cancer cell line (HCT116) to apoptosis caused with 5-fluorouracil, etoposide, or doxorubicin. Recombinant human VEGF165 did not completely inhibit this apoptosis. Conversely, overexpression of VEGF165 increased resistance to anti-cancer drug-induced apoptosis, while an anti-VEGF165-neutralizing antibody did not completely block the resistance. We prepared plasmids encoding full-length vegf mRNA with mutation of signal sequence, vegf mRNAs lacking untranslated regions (UTRs), or mutated 5'UTRs. Using these plasmids, we revealed that the 5'UTR of vegf mRNA possessed anti-apoptotic activity. The 5'UTR-mediated activity was not affected by a protein synthesis inhibitor, cycloheximide. We established HCT116 clones stably expressing either the vegf 5'UTR or the mutated 5'UTR. The clones expressing the 5'UTR, but not the mutated one, showed increased anchorage-independent growth in vitro and formed progressive tumors when implanted in athymic nude mice. Microarray and quantitative real-time PCR analyses indicated that the vegf 5'UTR-expressing tumors had up-regulated anti-apoptotic genes, multidrug-resistant genes, and growth-promoting genes, while pro-apoptotic genes were down-regulated. Notably, expression of signal transducers and activators of transcription 1 (STAT1) was markedly repressed in the 5'UTR-expressing tumors, resulting in down-regulation of a STAT1-responsive cluster of genes (43 genes). As a result, the tumors did not respond to interferon (IFN)alpha therapy at all. We showed that stable silencing of endogenous vegf mRNA in HCT116 cells enhanced both STAT1 expression and IFNalpha responses. CONCLUSIONS These findings suggest that cancer cells have a survival system that is regulated by vegf mRNA and imply that both vegf mRNA and its protein may synergistically promote the malignancy of tumor cells. Therefore, combination of anti-vegf transcript strategies, such as siRNA-based gene silencing, with anti-VEGF antibody treatment may improve anti-cancer therapies that target VEGF.
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Affiliation(s)
- Kiyoshi Masuda
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Shigetada Teshima-Kondo
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
- * To whom correspondence should be addressed. E-mail:
| | - Mina Mukaijo
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Naoko Yamagishi
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Yoshiko Nishikawa
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Kensei Nishida
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Tomoko Kawai
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Kazuhito Rokutan
- Department of Stress Science, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
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Weinzierl AO, Maurer D, Altenberend F, Schneiderhan-Marra N, Klingel K, Schoor O, Wernet D, Joos T, Rammensee HG, Stevanović S. A cryptic vascular endothelial growth factor T-cell epitope: identification and characterization by mass spectrometry and T-cell assays. Cancer Res 2008; 68:2447-54. [PMID: 18381453 DOI: 10.1158/0008-5472.can-07-2540] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular endothelial growth factor (VEGF) is involved in various physiologic processes, such as angiogenesis or wound healing, but is also crucial in pathologic events, such as tumor growth. Thus, clinical anti-VEGF treatments have been developed that could already show beneficial effects for cancer patients. In this article, we describe the first VEGF-derived CD8(+) T-cell epitope. The natural HLA ligand SRFGGAVVR was identified by differential mass spectrometry in two primary renal cell carcinomas (RCC) and was significantly overpresented on both tumor tissues. SRFGGAVVR is derived from a cryptic translated region of VEGF presumably by initiation of translation at the nonclassic start codon CUG(499). SRFGGAVVR-specific T cells were generated in vitro using peptide-loaded dendritic cells or artificial antigen-presenting cells. SRFGGAVVR-specific CD8(+) T cells, identified by HLA tetramer analysis after in vitro stimulation, were fully functional T effector cells, which were able to secrete IFN-gamma on stimulation and killed tumor cells in vitro. Additionally, we have quantitatively analyzed VEGF mRNA and protein levels in RCC tumor and normal tissue samples by gene chip analysis, quantitative reverse transcription-PCR, in situ hybridization, and bead-based immunoassay. In the future, T cells directed against VEGF as a tumor-associated antigen may represent a possible way of combining peptide-based anti-VEGF immunotherapy with already existent anti-VEGF cancer therapies.
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Affiliation(s)
- Andreas O Weinzierl
- Department of Immunology, Institute for Cell Biology, University of Tübingen, Germany
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Young RM, Wang SJ, Gordan JD, Ji X, Liebhaber SA, Simon MC. Hypoxia-mediated selective mRNA translation by an internal ribosome entry site-independent mechanism. J Biol Chem 2008; 283:16309-19. [PMID: 18430730 DOI: 10.1074/jbc.m710079200] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Although it is advantageous for hypoxic cells to inhibit protein synthesis and conserve energy, it is also important to translate mRNAs critical for adaptive responses to hypoxic stress. Because internal ribosome entry sites (IRES) have been postulated to mediate this preferential synthesis, we analyzed the 5 '-untranslated regions from a panel of stress-regulated mRNAs for m(7)GTP cap-independent translation and identified putative IRES elements in encephalomyocarditis virus, vascular endothelial growth factor, hypoxia-inducible factors (HIFs) 1alpha and 2alpha, glucose transporter-like protein 1, p57(Kip2), La, BiP, and triose phosphate isomerase transcripts. However, when capped and polyadenylated dicistronic RNAs were synthesized in vitro and transfected into cells, cellular IRES-mediated translation accounted for less than 1% that of the level of cap-dependent translation. Moreover, hypoxic stress failed to activate cap-independent synthesis, indicating that it is unlikely that this is the primary mechanism for the maintenance of the translation of these mRNAs under low O(2). Furthermore, although HIF-1alpha is frequently cited as an example of an mRNA that is preferentially translated, we demonstrate that under different levels and durations of hypoxic stress, changes in newly synthesized HIF-1alpha and beta-actin protein levels mirror alterations in corresponding mRNA abundance. In addition, our data suggest that cyclin-dependent kinase inhibitor p57(Kip2) and vascular endothelial growth factor mRNAs are selectively translated by an IRES-independent mechanism under hypoxic stress.
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Affiliation(s)
- Regina M Young
- Abramson Family Cancer Research Institute, Departments of Genetics and Medicine, University of Pennsylvania School of Medicine, and Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia Pennsylvania 19104, USA
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Bastide A, Karaa Z, Bornes S, Hieblot C, Lacazette E, Prats H, Touriol C. An upstream open reading frame within an IRES controls expression of a specific VEGF-A isoform. Nucleic Acids Res 2008; 36:2434-45. [PMID: 18304943 PMCID: PMC2367723 DOI: 10.1093/nar/gkn093] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Vascular endothelial growth factor A (VEGF-A) is a potent secreted mitogen critical for physiological and pathological angiogenesis. Regulation of VEGF-A occurs at multiple levels, including transcription, mRNA stabilization, splicing, translation and differential cellular localization of various isoforms. Recent advances in our understanding of the posttranscriptional regulation of VEGF-A are comprised of the identification of stabilizing mRNA-binding proteins and the discovery of two internal ribosomal entry sites (IRES) as well as two alternative initiation codons in the 5′UTR of the VEGF-A mRNA. We have previously reported that VEGF-A translation initiation at both the AUG and CUG codons is dependent on the exon content of the coding region. In this report, we show that the expression of different VEGF-A isoforms is regulated by a small upstream open reading frame (uORF) located within an internal ribosome entry site, which is translated through a cap-independent mechanism. This uORF acts as a cis-regulatory element that regulates negatively the expression of the VEGF 121 isoform. Our data provide a framework for understanding how VEGF-A mRNAs are translated, and how the production of the VEGF 121 isoform is secured under non-hypoxic environmental conditions.
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Affiliation(s)
- Amandine Bastide
- Institut National de la Santé et de la Recherche Médicale (INSERM), U858, CHU Rangueil, BP 84225, 31432 Toulouse cedex 4, France
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36
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Rioux-Leclercq N, Fergelot P, Zerrouki S, Leray E, Jouan F, Bellaud P, Epstein JI, Patard JJ. Plasma level and tissue expression of vascular endothelial growth factor in renal cell carcinoma: a prospective study of 50 cases. Hum Pathol 2007; 38:1489-95. [PMID: 17597181 DOI: 10.1016/j.humpath.2007.02.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 02/02/2007] [Accepted: 02/06/2007] [Indexed: 01/28/2023]
Abstract
Vascular endothelial growth factor (VEGF) is the major factor involved in angiogenesis. Although it is known that one of the functions of VEGF is to regulate neovascularization in renal cell carcinomas, the relationship between the production of VEGF in tumor tissue and its concentration in blood has not yet been studied. The aims of this study were to determine, in a series of conventional renal cell carcinoma (CRCC) cases, (1) VEGF expression and VEGF pattern in tumor cells, (2) the relationship between VEGF expression/pattern and VEGF levels in plasma (pVEGF), and (3) the association with usual clinical and pathologic prognostic factors. Fifty patients operated on for CRCC by radical nephrectomy were included. Clinical and histologic parameters were studied. VEGF expression and VEGF pattern in tumor cells was immunohistochemically recorded. pVEGF levels and platelet count were analyzed in relation to clinical and histologic parameters. Intratumoral VEGF expression associated with a cytoplasmic VEGF pattern was significantly higher in patients with high pVEGF levels (P = .01). Both VEGF expression and pVEGF levels were significantly correlated with Fuhrman grade (P = .002 and P = .01, respectively) and tumor stage (P = .006 and P = .008, respectively). In addition, VEGF expression was also correlated with tumor necrosis (P = .001) and progression (P = .001). We demonstrated that in CRCC with tumor necrosis, VEGF expression, pVEGF levels, and platelet count were significantly higher than in CRCC with no tumor necrosis (P = .001, P = .03, and P = .001, respectively). Our results revealed that cytoplasmic VEGF expression and pVEGF levels are associated with usual prognostic factors and progression in CRCC, which may allow VEGF to be used as a prognostic marker for CRCC, especially in patients with VEGF-targeted therapy.
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Affiliation(s)
- Nathalie Rioux-Leclercq
- Département d'Anatomie et de Cytologie Pathologiques, CHU Pontchaillou, 35033 Rennes Cedex 9, France; CNRS/UMR6061 IFR 140, Rennes University, 35043 Rennes Cedex, France.
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Kaczmarek MM, Waclawik A, Blitek A, Kowalczyk AE, Schams D, Ziecik AJ. Expression of the vascular endothelial growth factor-receptor system in the porcine endometrium throughout the estrous cycle and early pregnancy. Mol Reprod Dev 2007; 75:362-72. [PMID: 17874446 DOI: 10.1002/mrd.20815] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The objective of this study was to investigate the protein and mRNA expression of vascular endothelial growth factor (VEGF), VEGFR-1 (fms-like tyrosine kinase, Flt-1) and VEGFR-2 (fetal liver kinase-1/kinase insert domain-containing receptor, Flk-1/KDR) in the endometrium during the estrous cycle and early pregnancy in pigs. The VEGF-receptor system was localized in epithelial and stromal cells, blood vessels, and myometrium. Western blot analysis showed higher levels of VEGF protein during the periovulatory and periimplantation periods (P < 0.001, and P < 0.05, respectively). Constant expression of VEGF mRNA during the cycle and significant upregulation on Days 22-25 of gestation (vs. Days 9-17; P < 0.001) was observed. Stable levels of VEGFR-1 mRNA and protein were detected in the endometrium of cyclic animals. However, higher VEGFR-1 protein expression was found on Days 16-17 of the estrous cycle (P < 0.01) and Days 13-15 of gestation (P < 0.05). Protein expression of VEGFR-2 was elevated on Days 2-4 of the estrous cycle (P < 0.001), but mRNA levels were constant during the cycle. In pregnancy, VEGFR-2 protein expression started to increase after Day 15 (vs. Days 9-12; P < 0.05), but induction of VEGFR-2 mRNA expression occurred earlier on Days 13-15. It appears from the present study that the VEGF-receptor system is regulated in a temporal and spatial manner during the estrous cycle and early pregnancy in pigs. The results suggest that VEGF-A family members are probably involved in appropriate preparation of endometrium for implantation and in vascular events during implantation in pigs.
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Affiliation(s)
- Monika M Kaczmarek
- Division of Reproductive Endocrinology and Pathophysiology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
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Shenberger JS, Zhang L, Powell RJ, Barchowsky A. Hyperoxia enhances VEGF release from A549 cells via post-transcriptional processes. Free Radic Biol Med 2007; 43:844-52. [PMID: 17664148 PMCID: PMC1959513 DOI: 10.1016/j.freeradbiomed.2007.05.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 05/30/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
Exposure of animals to hyperoxia decreases lung VEGF mRNA expression concomitant with an acute increase in VEGF protein within the epithelial lining fluid (ELF). The VEGF concentration in ELF is in excess of that found in the plasma, leading to the hypothesis that hyperoxia stimulates the release of VEGF protein from stores within the extracellular matrix. To test this hypothesis in a cell culture system, we exposed A549 cells to 95% O(2) (Ox) for 48 h followed by recovery in room air (RA) for 24 h. We found that Ox increased VEGF protein two- to threefold within the medium at 48 h of exposure and during recovery. Heparin clearing revealed the medium to contain a 50/50 mixture of the heparin-binding (VEGF(165)) and heparin-nonbinding (VEGF(121)) proteins and that Ox increased both proteins equally. Transcriptional activation of VEGF seems unlikely to explain the increase in VEGF protein, as expression of full-length and splice variant VEGF mRNA was unchanged by hyperoxia. Analysis of cell-associated VEGF proteins found that Ox increased the expression of VEGF(121) and VEGF(165) proteins. Blocking binding sites with exogenous heparin enhanced VEGF protein in the medium from RA-grown cells, whereas heparinase digestion of bound VEGF revealed a greater reserve of VEGF protein in RA cells. Collectively these findings indicate that hyperoxia enhances the expression of VEGF(121/165) proteins and facilitates the release of VEGF(165) from cell-associated stores. Increases in VEGF in ELF may represent an adaptive response fostering cell survival and type II cell proliferation in O(2)-induced lung injury.
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Affiliation(s)
- Jeffrey S Shenberger
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA 17033-0850, USA.
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Artamonova II, Gelfand MS. Comparative Genomics and Evolution of Alternative Splicing: The Pessimists' Science. Chem Rev 2007; 107:3407-30. [PMID: 17645315 DOI: 10.1021/cr068304c] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Irena I Artamonova
- Group of Bioinformatics, Vavilov Institute of General Genetics, RAS, Gubkina 3, Moscow 119991, Russia
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40
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Errera FIV, Canani LH, Silva MER, Yeh E, Takahashi W, Santos KG, Souto KEP, Tschiedel B, Roisenberg I, Gross JL, Passos-Bueno MR. Functional vascular endothelial growth factor -634G>C SNP is associated with proliferative diabetic retinopathy: a case-control study in a Brazilian population of European ancestry. Diabetes Care 2007; 30:275-9. [PMID: 17259494 DOI: 10.2337/dc06-1399] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The purpose of this study was to evaluate the effect of the single nucleotide polymorphism (SNP) -634G>C at the 5' regulatory region of the vascular endothelial growth factor (VEGF) in the risk of proliferative diabetic retinopathy (PDR) in the Brazilian population of European ancestry with type 2 diabetes. RESEARCH DESIGN AND METHODS A case-control study was conducted in 501 type 2 diabetic patients of European ancestry. Patients underwent a standardized clinical, ophthalmological, and laboratory evaluation. Of these, 167 patients had PDR (case patients), and 334 were considered as control subjects (patients without PDR) for PDR. A reference population (110 individuals of European ancestry) was also evaluated. RESULTS No evidence of association between -634G>C/VEGF and the presence of diabetic retinopathy or type 2 diabetes was observed (P > 0.05). However, CC homozygous for the SNP -634G>C was significantly more frequent in patients with PDR (37 of 167; 22.2%) than in the corresponding control group (40 of 334; 12%) in accordance with a recessive model (P = 0.003). This effect was further observed when creatinine, BMI, sex, duration of type 2 diabetes, HDL cholesterol, and systolic blood pressure were taken into account (odds ratio 1.9 [95% CI 1.01-3.79], P = 0.04). CONCLUSIONS The presence of the allele -634C/VEGF in homozygosity is an independent risk factor for the development of PDR in type 2 diabetic patients of European ancestry.
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Affiliation(s)
- Flavia I V Errera
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, CEP 05508-900 São Paulo, Brazil
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Bornes S, Prado-Lourenco L, Bastide A, Zanibellato C, Iacovoni JS, Lacazette E, Prats AC, Touriol C, Prats H. Translational induction of VEGF internal ribosome entry site elements during the early response to ischemic stress. Circ Res 2007; 100:305-8. [PMID: 17255526 DOI: 10.1161/01.res.0000258873.08041.c9] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular endothelial growth factor-A (VEGF), a powerful factor involved in vasculogenesis and angiogenesis, is translationally regulated through 2 independent internal ribosome entry sites (IRESs A and B). IRESs enable an mRNA to be translated under conditions in which 5'-cap-dependent translation is inhibited, such as low oxygen stress. In the VEGF mRNA, IRES A influences translation at the canonical AUG codon, whereas the 5' IRES B element regulates initiation at an upstream, in frame CUG. In this study, we have developed transgenic mice expressing reporter genes under the control of these 2 IRESs. We reveal that although these IRESs display low activity in embryos and adult tissues, they permit efficient translation at early time points in ischemic muscle, a stress under which cap-dependent translation is inhibited. These results demonstrate the in vivo efficacy of the VEGF IRESs in response to a local environmental stress such as hypoxia.
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Affiliation(s)
- Stéphanie Bornes
- INSERM U858, Université Paul Sabatier, IFR31, BP 84225, 31432 Toulouse Cedex 04, France
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42
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Yoo PS, Mulkeen AL, Cha CH. Post-transcriptional regulation of vascular endothelial growth factor: Implications for tumor angiogenesis. World J Gastroenterol 2006; 12:4937-42. [PMID: 16937487 PMCID: PMC4087394 DOI: 10.3748/wjg.v12.i31.4937] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) is a potent secreted mitogen critical for physiologic and tumor angiogenesis. Regulation of VEGF occurs at several levels, including transcription, mRNA stabilization, translation, and differential cellular localization of various isoforms. Recent advances in our understanding of post-transcriptional regulation of VEGF include identification of the stabilizing mRNA binding protein, HuR, and the discovery of internal ribosomal entry sites in the 5'UTR of the VEGF mRNA. Monoclonal anti-VEGF antibody was recently approved for use in humans, but suffers from the need for high systemic doses. RNA interference (RNAi) technology is being used in vitro and in animal models with promising results. Here, we review the literature on post-transcriptional regulation of VEGF and describe recent progress in targeting these mechanisms for therapeutic benefit.
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Patard JJ, Rioux-Leclercq N, Fergelot P. Understanding the Importance of Smart Drugs in Renal Cell Carcinoma. Eur Urol 2006; 49:633-43. [PMID: 16481093 DOI: 10.1016/j.eururo.2006.01.016] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Accepted: 01/10/2006] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To understand the mode of action of the currently most investigated new drugs in renal cell carcinoma (RCC) and ultimately to analyze what should be the role of the urologist in this new therapeutic era. METHODS A comprehensive review of the peer-reviewed literature was performed on the topic of molecular pathways involved in RCC angiogenesis, vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGFR) and targeted molecular therapy for RCC. RESULTS Von Hippel-Lindau (VHL) disease has provided a model for understanding that the early inactivation of the VHL gene was responsible for accumulation of hypoxia-inducible factor and therefore activation of hypoxia-inducible genes such as VEGF, platelet-derived growth factor, erythropoietin, carbonic anhydrase IX and tumor growth factor alpha. The fact that such VHL inactivation also was found in up to 70% of sporadic RCC has been the rationale for developing new drugs targeting VEGF, VEGFR, platelet-derived growth factor receptor and tyrosine kinase receptors that are required for intracellular transduction. CONCLUSION Initial results from phase 2 trials in metastatic disease are very promising. There is a strong rationale for initiating adjuvant trials with those kind of agents in patients with high-risk localised tumors. Urologists who have a good understanding of prognostic parameters in localised RCC particularly should be involved in such new approaches.
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Ward ME, Toporsian M, Scott JA, Teoh H, Govindaraju V, Quan A, Wener AD, Wang G, Bevan SC, Newton DC, Marsden PA. Hypoxia induces a functionally significant and translationally efficient neuronal NO synthase mRNA variant. J Clin Invest 2006; 115:3128-39. [PMID: 16276418 PMCID: PMC1265848 DOI: 10.1172/jci20806] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Accepted: 08/30/2005] [Indexed: 11/17/2022] Open
Abstract
We tested the hypothesis that induction of neuronal NO synthase (nNOS) impairs vascular smooth muscle contractility after hypoxia. nNOS protein was increased in aorta, mesenteric arterioles, pulmonary arteries, brain, and diaphragm from rats exposed to 8% O2 for 48 hours and in human aortic SMCs after hypoxic incubation (1% O2). Ca-dependent NO synthase activity was increased in endothelium-denuded aortic segments from hypoxia-exposed rats. N-nitro-L-arginine methyl ester enhanced the contractile responses of endothelium-denuded aortic rings and mesenteric arterioles from hypoxia-exposed but not normoxic rats (P < 0.05). The hypoxia-inducible mRNA transcript expressed by human cells was found to contain a novel 5'-untranslated region, consistent with activation of transcription in the genomic region contiguous with exon 2. Translational efficiency of this transcript is markedly increased compared with previously described human nNOS mRNAs. Transgenic mice possessing a lacZ reporter construct under control of these genomic sequences demonstrated expression of the construct after exposure to hypoxia (8% O2, 48 hours) in the aorta, mesenteric arterioles, renal papilla, and brain. These results reveal a novel human nNOS promoter that confers the ability to rapidly upregulate nNOS expression in response to hypoxia with a functionally significant effect on vascular smooth muscle contraction.
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Affiliation(s)
- Michael E Ward
- Division of Respirology, University of Toronto, Toronto, Ontario, Canada.
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45
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Kozak M. A second look at cellular mRNA sequences said to function as internal ribosome entry sites. Nucleic Acids Res 2005; 33:6593-602. [PMID: 16314320 PMCID: PMC1298923 DOI: 10.1093/nar/gki958] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Accepted: 10/26/2005] [Indexed: 01/27/2023] Open
Abstract
This review takes a second look at a set of mRNAs that purportedly employ an alternative mechanism of initiation when cap-dependent translation is reduced during mitosis or stress conditions. A closer look is necessary because evidence cited in support of the internal initiation hypothesis is often flawed. When putative internal ribosome entry sequences (IRESs) are examined more carefully, they often turn out to harbor cryptic promoters or splice sites. This undermines the dicistronic assay, wherein IRES activity is measured by the ability to support translation of the 3' cistron. Most putative IRESs still have not been checked carefully to determine whether the dicistronic vector produces only the intended dicistronic mRNA. The widespread use of the pRF vector is a major problem because this vector, which has Renilla luciferase as the 5' cistron and firefly luciferase as the 3' cistron, has been found to generate spliced transcripts. RNA transfection assays could theoretically circumvent these problems, but most candidate IRESs score very weakly in that test. The practice of calling even very weak results 'positive' is one of the problems discussed herein. The extremely low efficiency of putative IRESs is inconsistent with their postulated biological roles.'
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Affiliation(s)
- Marilyn Kozak
- Department of Biochemistry, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
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Carrere N, Vernejoul F, Souque A, Asnacios A, Vaysse N, Pradayrol L, Susini C, Buscail L, Cordelier P. Characterization of the Bystander Effect of Somatostatin Receptor sst2 After In Vivo Gene Transfer into Human Pancreatic Cancer Cells. Hum Gene Ther 2005; 16:1175-93. [PMID: 16218779 DOI: 10.1089/hum.2005.16.1175] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pancreatic cancer is one of the most aggressive and devastating human malignancies. The present study was conducted to determine whether in vivo sst2 gene transfer into human pancreatic tumors would impair tumor progression, and to characterize sst2 antitumoral bystander mechanisms. sst2 administration, using the synthetic vector PEI, strongly inhibited tumor progression of human pancreatic adenocarcinoma, in vivo. sst2 gene transfer induced intratumoral production of its ligand somatostatin. Disruption of this autocrine loop by RNA interference completely reversed sst2 antitumoral activity. Mice depleted of natural killer (NK) cells did not hamper sst2 tumor growth inhibition. However, microvessel density and vascular endothelial growth factor (VEGF) expression were markedly reduced in sst2-transfected tumors, whereas sst3 somatostatin receptor was upregulated. Depleting somatostatin by RNA interference completely abolished the sst2 inhibitory effect on VEGF expression and tumor angiogenesis, and sst2-induced sst3 expression in peripheral tumor vessels. We conclude that in vivo sst2 gene transfer elicited intratumoral somatostatin production and strongly impaired human pancreatic tumor growth. NK cells were not involved in this antitumoral bystander effect. VEGF and tumor vascularization were identified as novel targets for sst2-mediated antitumoral bystander effect. sst3 somatostatin receptor was upregulated in sst2-transfected tumors. Therefore, in vivo gene delivery of sst2 receptor to target the angiogenic process in pancreatic ductal adenocarcinoma might be a new therapeutic approach for treatment of pancreatic cancer in patients with unresectable disease.
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Affiliation(s)
- Nicolas Carrere
- INSERM U531, Institut Louis Bugnard, IFR31, CHU Rangueil, 31432 Toulouse, France
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47
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Carrere N, Vernejoul F, Souque A, Asnacios A, Vaysse N, Pradayrol L, Susini C, Buscail L, Cordelier P. Characterization of the Bystander Effect of Somatostatin Receptor sst2 After In Vivo Gene Transfer into Human Pancreatic Cancer Cells. Hum Gene Ther 2005. [DOI: 10.1089/hum.2005.16.ft-120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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48
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Rosenbaum-Dekel Y, Fuchs A, Yakirevich E, Azriel A, Mazareb S, Resnick MB, Levi BZ. Nuclear localization of long-VEGF is associated with hypoxia and tumor angiogenesis. Biochem Biophys Res Commun 2005; 332:271-8. [PMID: 15896327 DOI: 10.1016/j.bbrc.2005.04.123] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 04/25/2005] [Indexed: 10/25/2022]
Abstract
Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that has a pivotal role in normal and pathological angiogenesis. VEGF has a long 5' untranslated region harboring an open reading frame (ORF) initiated by a CUG codon that is in-frame with the VEGF coding region. The ORF translation leads to the expression of a long isoform termed L-VEGF that is extended by an additional 180 amino acids. In this communication, we provide evidence that L-VEGF is subjected to proteolytic cleavage leading to the detachment of the 180 aa extension from the VEGF moiety. Using immunofluorescence staining, we show that upon hypoxia this 180 aa extension translocates to the nuclei of expressing cells. Accordingly, immunohistochemical staining of both normal and tumor tissue samples demonstrated restricted nuclear localization of the ORF, which was correlated with cytoplasmic localization of VEGF. This suggests that the 180 aa ORF is involved in VEGF-mediated angiogenic processes.
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Affiliation(s)
- Yifat Rosenbaum-Dekel
- Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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49
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Brockington A, Lewis C, Wharton S, Shaw PJ. Vascular endothelial growth factor and the nervous system. Neuropathol Appl Neurobiol 2004; 30:427-46. [PMID: 15488020 DOI: 10.1111/j.1365-2990.2004.00600.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Vascular endothelial growth factor (VEGF) is an angiogenic factor essential for the formation of new blood vessels during embryogenesis and in many pathological conditions. A new role for VEGF as a neurotrophic factor has recently emerged. In the developing nervous system, VEGF plays a pivotal role not only in vascularization, but also in neuronal proliferation, and the growth of coordinated vascular and neuronal networks. After injury to the nervous system, activation of VEGF and its receptors may restore blood supply and promote neuronal survival and repair. There is a growing body of evidence that VEGF is essential for motor neurone survival, and that aberrant regulation of VEGF may play a role in the degeneration of neurones in diseases such as amyotrophic lateral sclerosis.
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Affiliation(s)
- A Brockington
- Academic Neurology Unit, University of Sheffield, Medical School, Sheffield, UK
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