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Dailey W, Shunemann R, Yang F, Moore M, Knapp A, Chen P, Deshpande M, Metcalf B, Tompkins Q, Guzman AE, Felisky J, Mitton KP. Differences in activation of intracellular signaling in primary human retinal endothelial cells between isoforms of VEGFA 165. Mol Vis 2021; 27:191-205. [PMID: 33953532 PMCID: PMC8092446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 04/26/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose There are reports that a b-isoform of vascular endothelial growth factor-A 165 (VEGFA165b) is predominant in normal human vitreous, switching to the a-isoform (VEGFA165a) in the vitreous of some diseased eyes. Although these isoforms appear to have a different ability to activate the VEGF receptor 2 (VEGFR2) in various endothelial cells, the nature of their ability to activate intracellular signaling pathways is not fully characterized, especially in retinal endothelial cells. We determined their activation potential for two key intracellular signaling pathways (MAPK, AKT) over complete dose-response curves and compared potential effects on the expression of several VEGFA165 target genes in primary human retinal microvascular endothelial cells (HRMECs). Methods To determine full dose-response curves for the activation of MAPK (ERK1/2), AKT, and VEGFR2, direct in-cell western assays were developed using primary HRMECs. Potential differences in dose-response effects on gene expression markers related to endothelial cell and leukocyte adhesion (ICAM1, VCAM1, and SELE) and tight junctions (CLDN5 and OCLN) were tested with quantitative PCR. Results Activation dose-response analysis revealed much stronger activation of MAPK, AKT, and VEGFR2 by the a-isoform at lower doses. MAPK activation in primary HRMECs displayed a sigmoidal dose-response to a range of VEGFA 165 a concentrations spanning 10-250 pM, which shifted higher into the 100-5,000 pM range with VEGFA 165 b. Similar maximum activation of MAPK was achieved by both isoforms at high concentrations. Maximum activation of AKT by VEGFA 165 b was only half of the maximum activation from VEGFA 165 a. At a lower intermediate dose, where VEGFA 165 a activated intracellular signaling stronger than VEGFA 165 b, the changes in VEGFA target gene expression were generally greater with VEGFA 165 a. Conclusions In primary HRMECs, VEGFA 165 a could maximally activate MAPK and AKT at lower concentrations where VEGFA 165 b had relatively little effect. The timing for maximum activation of MAPK was similar for the isoforms, which is different from that reported for non-retinal endothelial cells. Although differences in VEGFA 165 a and VEGFA 165 b are limited to the sequence of their six C-terminal six amino acids, this results in a large difference in their ability to activate at least two key intracellular signaling pathways and VEGF-target gene expression in primary human retinal endothelial cells.
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Yuan S, Pardue S, Shen X, Alexander JS, Orr AW, Kevil CG. Hydrogen sulfide metabolism regulates endothelial solute barrier function. Redox Biol 2016; 9:157-166. [PMID: 27552214 PMCID: PMC4993857 DOI: 10.1016/j.redox.2016.08.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/03/2016] [Accepted: 08/10/2016] [Indexed: 12/14/2022] Open
Abstract
Hydrogen sulfide (H2S) is an important gaseous signaling molecule in the cardiovascular system. In addition to free H2S, H2S can be oxidized to polysulfide which can be biologically active. Since the impact of H2S on endothelial solute barrier function is not known, we sought to determine whether H2S and its various metabolites affect endothelial permeability. In vitro permeability was evaluated using albumin flux and transendothelial electrical resistance. Different H2S donors were used to examine the effects of exogenous H2S. To evaluate the role of endogenous H2S, mouse aortic endothelial cells (MAECs) were isolated from wild type mice and mice lacking cystathionine γ-lyase (CSE), a predominant source of H2S in endothelial cells. In vivo permeability was evaluated using the Miles assay. We observed that polysulfide donors induced rapid albumin flux across endothelium. Comparatively, free sulfide donors increased permeability only with higher concentrations and at later time points. Increased solute permeability was associated with disruption of endothelial junction proteins claudin 5 and VE-cadherin, along with enhanced actin stress fiber formation. Importantly, sulfide donors that increase permeability elicited a preferential increase in polysulfide levels within endothelium. Similarly, CSE deficient MAECs showed enhanced solute barrier function along with reduced endogenous bound sulfane sulfur. CSE siRNA knockdown also enhanced endothelial junction structures with increased claudin 5 protein expression. In vivo, CSE genetic deficiency significantly blunted VEGF induced hyperpermeability revealing an important role of the enzyme for barrier function. In summary, endothelial solute permeability is critically regulated via exogenous and endogenous sulfide bioavailability with a prominent role of polysulfides. Polysulfide from cystathionine γ-lyase (CSE) and exogenous polysulfide donors increases endothelial permeability. The ability of polysulfide to increase permeability is associated with junction disruption and stress fiber formation. CSE expression in vivo regulates VEGF induced hyper-permeability.
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Affiliation(s)
- Shuai Yuan
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA
| | - Sibile Pardue
- Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA
| | - Xinggui Shen
- Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA
| | - J Steven Alexander
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA
| | - A Wayne Orr
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA; Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA
| | - Christopher G Kevil
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA; Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA; Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA; Center for Cardiovascular Diseases and Sciences, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA.
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Yao H, Shi W, Wu J, Xu C, Wang J, Shao Y, Wu X, Zhang Z. Endothelial Rac1 is essential for hematogenous metastasis to the lung. Oncotarget 2016; 6:17501-13. [PMID: 25991673 PMCID: PMC4627324 DOI: 10.18632/oncotarget.3766] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 04/28/2015] [Indexed: 12/22/2022] Open
Abstract
A variety of vasoactive stimuli induce endothelial permeability through Rac1, a membrane of Rho small GTPases. Here, we determine whether tumor-secreted vasoactive stimulant through Rac1 inducing permeability contributes to hematogenous metastasis. Activation of Rac1 was assayed in human umbilical vein endothelial cells (HUVEC), transendothelial passages were measured by Transwell chambers, and hematogenously metastatic mouse model was generated by intravenous injection with Lewis lung carcinoma cells (LLC). LLC secreted abundant vascular endothelial growth factor (VEGF) in the culture media and sera of mice bearing LLC xenografts or metastatic LLC, and VEGF activated Rac1 through VEGF receptors/PI3Kβ signaling cascade, resulting in hyperoxidative stress and consequent hyperpermeability in HUVEC. Moreover, in co-culture of LLC and HUVEC, significant increases in endothelial permeability and transendothelial migration of LLC were robustly attenuated by either anti-VEGF neutralizing antibody or Rac1 knockdown in HUVEC. Finally, in metastatic mouse model, deletion of one copy of Rac1 in endothelium not only significantly attenuated LLC-induced vascular permeability, but robustly reduced the metastasis of LLC to lungs. This study supports that tumor-secreted vasoactive stimuli activate Rac1 to induce permeability and consequent transendothelial migration of tumor cells, and that loss of Rac1 function in endothelium is an effective therapeutic intervention for hematogenous metastasis.
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Affiliation(s)
- Hongyi Yao
- Department of Pharmacy, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Wei Shi
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Junsong Wu
- The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Chengyun Xu
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Jirong Wang
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yanan Shao
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ximei Wu
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Zhongmiao Zhang
- Department of Pharmacy, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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Eswarappa SM, Fox PL. Antiangiogenic VEGF-Ax: A New Participant in Tumor Angiogenesis. Cancer Res 2015; 75:2765-9. [PMID: 26122849 DOI: 10.1158/0008-5472.can-14-3805] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 03/25/2015] [Indexed: 11/16/2022]
Abstract
The transcript of the angiogenic factor vascular endothelial growth factor A (VEGF-A) is subject to a multitude of stimulus-dependent, posttranscriptional regulatory events, consistent with its unusually long 3' untranslated region. We have recently reported translational readthrough of VEGFA mRNA whereby translating ribosomes traverse the canonical stop codon to a conserved, downstream stop codon, generating VEGF-Ax ("x" for extended), a novel, extended isoform with an additional 22 amino acids appended at the C-terminus. This event is the first vertebrate example of protein-regulated, programmed translational readthrough that generates a protein with a known function. Remarkably, VEGF-Ax exhibits potent antiangiogenic activity, both in vitro and in vivo, thus raising profound clinical implications, particularly with respect to cancer treatment. In this review, we discuss the potential of VEGF-Ax as a therapeutic agent and drug target, as well as its possible role in the failure of, or resistance to, conventional anti-VEGF therapies in many types of cancers.
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Affiliation(s)
- Sandeepa M Eswarappa
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio. Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Paul L Fox
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio.
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Eswarappa SM, Potdar AA, Koch WJ, Fan Y, Vasu K, Lindner D, Willard B, Graham LM, DiCorleto PE, Fox PL. Programmed translational readthrough generates antiangiogenic VEGF-Ax. Cell 2014; 157:1605-18. [PMID: 24949972 DOI: 10.1016/j.cell.2014.04.033] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/21/2014] [Accepted: 04/04/2014] [Indexed: 12/20/2022]
Abstract
Translational readthrough, observed primarily in less complex organisms from viruses to Drosophila, expands the proteome by translating select transcripts beyond the canonical stop codon. Here, we show that vascular endothelial growth factor A (VEGFA) mRNA in mammalian endothelial cells undergoes programmed translational readthrough (PTR) generating VEGF-Ax, an isoform containing a unique 22-amino-acid C terminus extension. A cis-acting element in the VEGFA 3' UTR serves a dual function, not only encoding the appended peptide but also directing the PTR by decoding the UGA stop codon as serine. Heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 binds this element and promotes readthrough. Remarkably, VEGF-Ax exhibits antiangiogenic activity in contrast to the proangiogenic activity of VEGF-A. Pathophysiological significance of VEGF-Ax is indicated by robust expression in multiple human tissues but depletion in colon adenocarcinoma. Furthermore, genome-wide analysis revealed AGO1 and MTCH2 as authentic readthrough targets. Overall, our studies reveal a novel protein-regulated PTR event in a vertebrate system.
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Affiliation(s)
- Sandeepa M Eswarappa
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Alka A Potdar
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - William J Koch
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Yi Fan
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Kommireddy Vasu
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Daniel Lindner
- Taussig Cancer Center, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Belinda Willard
- Mass Spectrometry Laboratory for Protein Sequencing, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Linda M Graham
- Department of Biomedical Engineering, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Paul E DiCorleto
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Paul L Fox
- Department of Cellular and Molecular Medicine, The Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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The effects of inflammatory cytokines on lymphatic endothelial barrier function. Angiogenesis 2013; 17:395-406. [PMID: 24141404 DOI: 10.1007/s10456-013-9393-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 09/23/2013] [Indexed: 12/22/2022]
Abstract
Proper lymphatic function is necessary for the transport of fluids, macromolecules, antigens and immune cells out of the interstitium. The lymphatic endothelium plays important roles in the modulation of lymphatic contractile activity and lymph transport, but it's role as a barrier between the lymph and interstitial compartments is less well understood. Alterations in lymphatic function have long been associated with edema and inflammation although the integrity of the lymphatic endothelial barrier during inflammation is not well-defined. In this paper we evaluated the integrity of the lymphatic barrier in response to inflammatory stimuli commonly associated with increased blood endothelial permeability. We utilized in vitro assays of lymphatic endothelial cell (LEC) monolayer barrier function after treatment with different inflammatory cytokines and signaling molecules including TNF-α, IL-6, IL-1β, IFN-γ and LPS. Moderate increases in an index of monolayer barrier dysfunction were noted with all treatments (20-60 % increase) except IFN-γ which caused a greater than 2.5-fold increase. Cytokine-induced barrier dysfunction was blocked or reduced by the addition of LNAME, except for IL-1β and LPS treatments, suggesting a regulatory role for nitric oxide. The decreased LEC barrier was associated with modulation of both intercellular adhesion and intracellular cytoskeletal activation. Cytokine treatments reduced the expression of VE-cadherin and increased scavenging of β-catenin in the LECs and this was partially reversed by LNAME. Likewise the phosphorylation of myosin light chain 20 at the regulatory serine 19 site, which accompanied the elevated monolayer barrier dysfunction in response to cytokine treatment, was also blunted by LNAME application. This suggests that the lymphatic barrier is regulated during inflammation and that certain inflammatory signals may induce large increases in permeability.
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Cromer WE, Ganta CV, Patel M, Traylor J, Kevil CG, Alexander JS, Mathis JM. VEGF-A isoform modulation in an preclinical TNBS model of ulcerative colitis: protective effects of a VEGF164b therapy. J Transl Med 2013; 11:207. [PMID: 24020796 PMCID: PMC3848761 DOI: 10.1186/1479-5876-11-207] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 08/28/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Ulcerative colitis (UC) is the most common form of inflammatory bowel disease in the USA. A key component of UC is the increase in inflammatory angiogenesis of the colon during active disease. This increase is driven to a great extent by the over expression of VEGF-A. Recently, VEGF165(b) (VEGF164(b) in mouse), an anti-angiogenic form of VEGF-A was described and its regulation was determined to be disturbed in many pathologies such as cancer and pre-eclampsia. RESULTS The aims of this study were to examine the role of this inhibitory VEGF by expressing this molecule in a model of intestinal inflammation, and to evaluate its expression as a potential new therapeutic approach for treating UC. A modified model of TNBS colitis was used to determine the effects of rVEGF164(b) expression on colon inflammation. Expansion of the vascular system was assessed by immunhistochemical methods and macro- and microscopic measurements of inflammation in the colon were measured. Leukocyte invasion of the tissue was measured by myeloperoxidase assay and identification and counting of lymphoid follicles. Both angio- and lymphangiogenesis were reduced by expression of rVEGF164(b), which correlated with reduction in both gross and microscopic inflammatory scores. Leukocyte invasion of the tissue was also reduced by rVEGF164(b) expression. CONCLUSIONS This is the first report using an endogenous inhibitory VEGF-A isoform for therapy in a model of experimental colitis. Inhibitory VEGF molecules play an important role in maintenance of gut homeostasis and may be dysregulated in UC. The results of this study suggest that restoration of rVEGF164(b) expression has anti-inflammatory activity in a TNBS model and warrants further examination as a possible therapeutic for UC.
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Affiliation(s)
- Walter E Cromer
- Gene Therapy Program, LSU Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
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Zawieja SD, Wang W, Wu X, Nepiyushchikh ZV, Zawieja DC, Muthuchamy M. Impairments in the intrinsic contractility of mesenteric collecting lymphatics in a rat model of metabolic syndrome. Am J Physiol Heart Circ Physiol 2011; 302:H643-53. [PMID: 22159997 DOI: 10.1152/ajpheart.00606.2011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Numerous studies on metabolic syndrome (MetSyn), a cluster of metabolic abnormalities, have demonstrated its profound impact on cardiovascular and blood microvascular health; however, the effects of MetSyn on lymphatic function are not well understood. We hypothesized that MetSyn would modulate lymphatic muscle activity and alter muscularized lymphatic function similar to the impairment of blood vessel function associated with MetSyn, particularly given the direct proximity of the lymphatics to the chronically inflamed adipose depots. To test this hypothesis, rats were placed on a high-fructose diet (60%) for 7 wk, and their progression to MetSyn was assessed through serum insulin and triglyceride levels in addition to the expression of metabolic and inflammatory genes in the liver. Mesenteric lymphatic vessels were isolated and subjected to different transmural pressures while lymphatic pumping and contractile parameters were evaluated. Lymphatics from MetSyn rats had significant negative chronotropic effects at all pressures that effectively reduced the intrinsic flow-generating capacity of these vessels by ∼50%. Furthermore, lymphatics were remodeled to a significantly smaller diameter in the animals with MetSyn. Wire myograph experiments demonstrated that permeabilized lymphatics from the MetSyn group exhibited a significant decrease in force generation and were less sensitive to Ca(2+), although there were no significant changes in lymphatic muscle cell coverage or morphology. Thus, our data provide the first evidence that MetSyn induces a remodeling of collecting lymphatics, thereby effectively reducing their potential load capabilities and impairing the intrinsic contractility required for proper lymph flow.
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Affiliation(s)
- Scott D Zawieja
- Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center College of Medicine, College Station, TX 77843, USA
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