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Tazat K, Pomeraniec-Abudy L, Hector-Greene M, Szilágyi SS, Sharma S, Cai EM, Corona AL, Ehrlich M, Blobe GC, Henis YI. ALK1 regulates the internalization of endoglin and the type III TGF-β receptor. Mol Biol Cell 2021; 32:605-621. [PMID: 33566682 PMCID: PMC8101464 DOI: 10.1091/mbc.e20-03-0199] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Complex formation and endocytosis of transforming growth factor-β (TGF-β) receptors play important roles in signaling. However, their interdependence remained unexplored. Here, we demonstrate that ALK1, a TGF-β type I receptor prevalent in endothelial cells, forms stable complexes at the cell surface with endoglin and with type III TGF-β receptors (TβRIII). We show that ALK1 undergoes clathrin-mediated endocytosis (CME) faster than ALK5, type II TGF-β receptor (TβRII), endoglin, or TβRIII. These complexes regulate the endocytosis of the TGF-β receptors, with a major effect mediated by ALK1. Thus, ALK1 enhances the endocytosis of TβRIII and endoglin, while ALK5 and TβRII mildly enhance endoglin, but not TβRIII, internalization. Conversely, the slowly endocytosed endoglin has no effect on the endocytosis of either ALK1, ALK5, or TβRII, while TβRIII has a differential effect, slowing the internalization of ALK5 and TβRII, but not ALK1. Such effects may be relevant to signaling, as BMP9-mediated Smad1/5/8 phosphorylation is inhibited by CME blockade in endothelial cells. We propose a model that links TGF-β receptor oligomerization and endocytosis, based on which endocytosis signals are exposed/functional in specific receptor complexes. This has broad implications for signaling, implying that complex formation among various receptors regulates their surface levels and signaling intensities.
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Affiliation(s)
- Keren Tazat
- Department of Neurobiology, Tel Aviv University, Tel Aviv 6997801, Israel
| | | | | | | | - Swati Sharma
- Department of Neurobiology, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Elise M Cai
- Department of Medicine, Duke University Medical Center, Durham, NC 27708
| | - Armando L Corona
- Department of Medicine, Duke University Medical Center, Durham, NC 27708
| | - Marcelo Ehrlich
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Gerard C Blobe
- Department of Medicine, Duke University Medical Center, Durham, NC 27708
| | - Yoav I Henis
- Department of Neurobiology, Tel Aviv University, Tel Aviv 6997801, Israel
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2
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Croy BA, Ashkar AA, Minhas K, Greenwood JD. Can Murine Uterine Natural Killer Cells Give Insights Into the Pathogenesis of Preeclampsia? ACTA ACUST UNITED AC 2016. [DOI: 10.1177/107155760000700104] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- B. Anne Croy
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | | | | | - James D. Greenwood
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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3
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Shao Y, Cheng Z, Li X, Chernaya V, Wang H, Yang XF. Immunosuppressive/anti-inflammatory cytokines directly and indirectly inhibit endothelial dysfunction--a novel mechanism for maintaining vascular function. J Hematol Oncol 2014; 7:80. [PMID: 25387998 PMCID: PMC4236671 DOI: 10.1186/s13045-014-0080-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 10/13/2014] [Indexed: 12/14/2022] Open
Abstract
Endothelial dysfunction is a pathological status of the vascular system, which can be broadly defined as an imbalance between endothelium-dependent vasoconstriction and vasodilation. Endothelial dysfunction is a key event in the progression of many pathological processes including atherosclerosis, type II diabetes and hypertension. Previous reports have demonstrated that pro-inflammatory/immunoeffector cytokines significantly promote endothelial dysfunction while numerous novel anti-inflammatory/immunosuppressive cytokines have recently been identified such as interleukin (IL)-35. However, the effects of anti-inflammatory cytokines on endothelial dysfunction have received much less attention. In this analytical review, we focus on the recent progress attained in characterizing the direct and indirect effects of anti-inflammatory/immunosuppressive cytokines in the inhibition of endothelial dysfunction. Our analyses are not only limited to the importance of endothelial dysfunction in cardiovascular disease progression, but also expand into the molecular mechanisms and pathways underlying the inhibition of endothelial dysfunction by anti-inflammatory/immunosuppressive cytokines. Our review suggests that anti-inflammatory/immunosuppressive cytokines serve as novel therapeutic targets for inhibiting endothelial dysfunction, vascular inflammation and cardio- and cerebro-vascular diseases.
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Affiliation(s)
- Ying Shao
- Department of Pharmacology, Center for Metabolic Disease Research and Cardiovascular Research Center, Temple University School of Medicine, MERB 1059, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
| | - Zhongjian Cheng
- Department of Pharmacology, Center for Metabolic Disease Research and Cardiovascular Research Center, Temple University School of Medicine, MERB 1059, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
| | - Xinyuan Li
- Department of Pharmacology, Center for Metabolic Disease Research and Cardiovascular Research Center, Temple University School of Medicine, MERB 1059, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
| | - Valeria Chernaya
- Department of Pharmacology, Center for Metabolic Disease Research and Cardiovascular Research Center, Temple University School of Medicine, MERB 1059, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
| | - Hong Wang
- Department of Pharmacology, Center for Metabolic Disease Research and Cardiovascular Research Center, Temple University School of Medicine, MERB 1059, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
| | - Xiao-feng Yang
- Department of Pharmacology, Center for Metabolic Disease Research and Cardiovascular Research Center, Temple University School of Medicine, MERB 1059, 3500 North Broad Street, Philadelphia, PA, 19140, USA. .,Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA, 19140, USA.
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4
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Imoukhuede PI, Dokun AO, Annex BH, Popel AS. Endothelial cell-by-cell profiling reveals the temporal dynamics of VEGFR1 and VEGFR2 membrane localization after murine hindlimb ischemia. Am J Physiol Heart Circ Physiol 2013; 304:H1085-93. [PMID: 23376830 DOI: 10.1152/ajpheart.00514.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
VEGF receptor (VEGFR) cell surface localization plays a critical role in transducing VEGF signaling toward angiogenic outcomes, and quantitative characterization of these parameters is critical to advancing computational models for predictive medicine. However, studies to this point have largely examined intact muscle; thus, essential data on the cellular localization of the receptors within the tissue are currently unknown. Therefore, our aims were to quantitatively analyze VEGFR localization on endothelial cells (ECs) from mouse hindlimb skeletal muscles after the induction of hindlimb ischemia, an established model for human peripheral artery disease. Flow cytometry was used to measure and compare the ex vivo surface localization of VEGFR1 and VEGFR2 on CD31(+)/CD34(+) ECs 3 and 10 days after unilateral ligation of the femoral artery. We determined that 3 days after hindlimb ischemia, VEGFR2 surface levels were decreased by 80% compared with ECs from the nonischemic limb; 10 days after ischemia, we observed a twofold increase in surface levels of the modulatory receptor, VEGFR1, along with increased proliferating cell nuclear antigen, urokinase plasminogen activator, and urokinase plasminogen activator receptor mRNA expression compared with the nonischemic limb. The significant upregulation of VEGFR1 surface levels indicates that VEGFR1 indeed plays a critical role in the ischemia-induced perfusion recovery process, a process that includes both angiogenesis and arteriogenesis. The quantification of these dissimilarities, for the first time ex vivo, provides insights into the balance of modulatory (VEGFR1) and proangiogenic (VEGFR2) receptors in ischemia and lays the foundation for systems biology approaches toward therapeutic angiogenesis.
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Affiliation(s)
- P I Imoukhuede
- Department of Bioengineering, University of Illinois, Urbana, Illinois 61801, USA.
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5
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Lu X, Rosenbusch RF. Endothelial cells from bovine pulmonary microvasculature respond to Mycoplasma bovis preferentially with signals for mononuclear cell transmigration. Microb Pathog 2004; 37:253-61. [PMID: 15519046 DOI: 10.1016/j.micpath.2004.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 08/02/2004] [Accepted: 08/02/2004] [Indexed: 10/26/2022]
Abstract
Mycoplasma bovis can cause arthritis or mastitis following pneumonia and mycoplasmemia in cattle. Interactions with pulmonary vascular endothelium have been recorded as localized vasculitis, perivascular mononuclear cell infiltrations, and accumulation of inflammatory cells in lesions. We compared adhesion mediators and cytokine gene expression as well as cytotoxicity of cultured primary bovine aortic and bovine pulmonary microvascular endothelial cells (BPMEC) challenged with M. bovis. We also tested if abscess-forming ability of strains of M. bovis is associated with changes on endothelial cells. Increased VCAM-1 surface expression was found in both cell types, while only infected BPMEC increased MCP-1 transcription, both mediators specific for mononuclear cell transmigration. Given no induction of ICAM-1 mRNA in either cell type, induction of IL-8 mRNA by BPMEC suggested that neutrophil transmigration was signaled in microvascular areas. Infected BPMEC showed early induction of IL-1beta and IL-6 mRNA. Excepting VCAM-1, differential strain effects were limited to BPMEC and not correlated with their abscess-forming capability. In addition, only strain DSA16 had minor cytotoxic effect on both cell types. We thus show that BPMEC are more susceptible than aortic cells to M. bovis-induced activation. Activation preferentially yielded signals for mononuclear cell transmigration, correlating well with in vivo observations of infiltrating cells at pulmonary sites.
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Affiliation(s)
- Xiaodong Lu
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, USA.
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6
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Abstract
OBJECTIVE To review recent advances in the field of endothelial cell heterogeneity, and to apply this knowledge to an understanding of site-specific vasculopathy, including acute lung injury. DATA SOURCES AND STUDY SELECTION Published research and review articles in the English language related to endothelial cell biology and endothelial cell heterogeneity. DATA EXTRACTION AND SYNTHESIS The results of published studies have been used to provide a perspective of endothelial cell phenotypes in health and disease. CONCLUSIONS The structure and function of endothelial cells are differentially regulated in space and time. Far from being a giant monopoly of homogeneous cells, the endothelium represents a consortium of smaller enterprises of cells located within blood vessels of different tissues. Although united in certain functions, each enterprise is uniquely adapted to meet the demands of the underlying tissue. The endothelium may also vary in its response to pathophysiologic stimuli and therefore contribute to the focal nature of vasculopathic disease states. In acute lung injury, the unique properties of the endothelium may conspire with systemic imbalances to localize pathology to the pulmonary vasculature.
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Affiliation(s)
- William C Aird
- Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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7
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Flanders KC, Burmester JK. Medical applications of transforming growth factor-beta. Clin Med Res 2003; 1:13-20. [PMID: 15931280 PMCID: PMC1069016 DOI: 10.3121/cmr.1.1.13] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2002] [Accepted: 08/26/2002] [Indexed: 01/18/2023]
Abstract
Transforming growth factor-beta (TGF-beta) proteins and their antagonists have entered clinical trials. These multi-functional regulators of cell growth and differentiation induce extracellular matrix proteins and suppress the immune system making TGF-betas useful in treatment of wounds with impaired healing, mucositis, fractures, ischemia-reperfusion injuries, and autoimmune disease. In diseases such as keloids, glomerulonephritis and pulmonary fibrosis, excessive expression of TGF-beta has been implicated as being responsible for accumulation of detrimental scar tissue. In these conditions, agents that block TGF-beta have prevented or reversed disease. Similarly, in carcinogenesis, blocking TGF-beta activity may be valuable in stimulating an immune response towards metastasis. As these blocking agents receive approval, we will likely have new therapies for previously recalcitrant diseases.
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Affiliation(s)
- Kathleen C Flanders
- Laboratory of Cell Regulation and Carcinogenesis, National Institutes of Health, Bethesda, Maryland, USA
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8
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Blobe GC, Schiemann WP, Pepin MC, Beauchemin M, Moustakas A, Lodish HF, O'Connor-McCourt MD. Functional roles for the cytoplasmic domain of the type III transforming growth factor beta receptor in regulating transforming growth factor beta signaling. J Biol Chem 2001; 276:24627-37. [PMID: 11323414 DOI: 10.1074/jbc.m100188200] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Transforming growth factor beta (TGF-beta) signals through three high affinity cell surface receptors, TGF-beta type I, type II, and type III receptors. The type III receptor, also known as betaglycan, binds to the type II receptor and is thought to act solely by "presenting" the TGF-beta ligand to the type II receptor. The short cytoplasmic domain of the type III receptor is thought to have no role in TGF-beta signaling because deletion of this domain has no effect on association with the type II receptor, or with the presentation role of the type III receptor. Here we demonstrate that the cytoplasmic domains of the type III and type II receptors interact specifically in a manner dependent on the kinase activity of the type II receptor and the ability of the type II receptor to autophosphorylate. This interaction results in the phosphorylation of the cytoplasmic domain of the type III receptor by the type II receptor. The type III receptor with the cytoplasmic domain deleted is able to bind TGF-beta, to bind the type II receptor, and to enhance TGF-beta binding to the type II receptor but is unable to enhance TGF-beta2 signaling, determining that the cytoplasmic domain is essential for some functions of the type III receptor. The type III receptor functions by selectively binding the autophosphorylated type II receptor via its cytoplasmic domain, thus promoting the preferential formation of a complex between the autophosphorylated type II receptor and the type I receptor and then dissociating from this active signaling complex. These studies, for the first time, elucidate important functional roles of the cytoplasmic domain of the type III receptor and demonstrate that these roles are essential for regulating TGF-beta signaling.
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Affiliation(s)
- G C Blobe
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
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9
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Abstract
It has become well accepted that solid tumors must create a vascular system for nutrient delivery and waste removal in order to grow appreciably. This process, angiogenesis, is critical to the progression of gliomas, with vascular changes accompanying the advancement of these tumors. The cascade of events in this process of blood vessel formation involves a complex interplay between tumor cells, endothelial cells, and their surrounding basement membranes in which enzymatic degradation of surrounding ground substance and subsequent endothelial cell migration, proliferation, and tube formation occurs. It is likely that a host of growth factors is responsible for mediating these key events. To date, a role for Vascular Endothelial Growth Factor (VEGF) in glioma angiogenesis has been convincingly demonstrated. This review explores the contribution of other growth factors--Fibroblast Growth Factors (FGFs), Platelet-Derived Growth Factor (PDGF), Epidermal Growth Factor (EGF), and Transforming Growth Factors (TGFs)--to glioma angiogenesis. These growth factors may influence glioma angiogenesis by directly stimulating endothelial cell proliferation, by mediating the expression of key proteases on endothelial cells necessary for angiogenesis, or by regulating the expression of VEGF and of each other.
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Affiliation(s)
- I F Dunn
- Brain Tumor Research Center, Brigham and Women's Hospital, Department of Surgery, Harvard Medical School, Boston, MA, USA
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10
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Wong SH, Hamel L, Chevalier S, Philip A. Endoglin expression on human microvascular endothelial cells association with betaglycan and formation of higher order complexes with TGF-beta signalling receptors. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:5550-60. [PMID: 10951214 DOI: 10.1046/j.1432-1327.2000.01621.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Transforming growth factor-beta (TGF-beta) plays an important role in angiogenesis and vascular function. Endoglin, a transmembrane TGF-beta binding protein, is highly expressed on vascular endothelial cells and is the target gene for the hereditary haemorrhagic telangiectasia type I (HHT1), a dominantly inherited vascular disorder. The specific function of endoglin responsible for HHT1 is believed to involve alterations in TGF-beta responses. The initial interactions on the cell surface between endoglin and TGF-beta receptors may be an important mechanism by which endoglin modulates TGF-beta signalling, and thereby responses. Here it is shown that on human microvascular endothelial cells, endoglin is co-expressed and is associated with betaglycan, a TGF-beta accessory receptor with which endoglin shares limited amino acid homology. This complex formation may occur in either a ligand-dependent or a ligand-independent manner. In addition, the occurrence of three higher order complexes containing endoglin, type II and/or type I TGF-beta receptors, on these cells is demonstrated. Our findings suggest that endoglin may modify TGF-beta signalling by interacting with both betaglycan and the TGF-beta signalling receptors at physiological receptor concentrations and ratios.
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Affiliation(s)
- S H Wong
- Division of Plastic Surgery, Montreal General Hospital and Department of Surgery, McGill University, Montreal, Quebec, Canada
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11
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Liu A, Dardik A, Ballermann BJ. Neutralizing TGF-beta1 antibody infusion in neonatal rat delays in vivo glomerular capillary formation 1. Kidney Int 1999; 56:1334-48. [PMID: 10504486 DOI: 10.1046/j.1523-1755.1999.00661.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The interruption of transforming growth factor-beta (TGF-beta) signaling with dominant negative type II TGF-beta receptors in bovine glomerular endothelial cells abrogates capillary morphogenesis in vitro, and genetic defects in the TGF-beta1 signaling cascade in mice and humans result in abnormalities of blood vessel morphology. This study sought to determine whether TGF-beta1 participates in renal glomerular capillary development in vivo. METHODS To inhibit TGF-beta1 action, neutralizing anti-TGF-beta1 IgG was infused intra-arterially into the suprarenal aorta of three-day-old rats, and the glomerular endothelial cell appearance was evaluated two days later by immunohistochemical detection of the endothelium-specific von Willebrand factor, in situ analysis of vascular endothelial growth factor receptor binding, and morphometric study of developing glomerular structures by transmission electron microscopy. RESULTS The infusion of neutralizing the TGF-beta1 antibody markedly reduced the invasion of comma- and S-shaped bodies by endothelial cells, and inhibited organization of endothelial cells into capillaries in these structures. In addition, capillary lumen formation and endothelial cell fenestration in developing cortical, but not in deep, already mature glomeruli were inhibited by neutralizing TGF-beta1 antibody. Seven days after TGF-beta1 antibody infusion, glomeruli appeared normal, and no reduction in glomerular number was observed. CONCLUSIONS These findings suggest that TGF-beta1 plays a critical role in the formation of glomerular capillaries during renal development in the rat, and that flattening and fenestration of glomerular capillaries require the action of TGF-beta1.
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Affiliation(s)
- A Liu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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12
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Giannini S, Cresci B, Pala L, Ciucci A, Manuelli C, Fujita-Yamaguchi Y, Cappugi P, Rotella CM. Human glomerular endothelial cells IGFBPs are regulated by IGF-I and TGF-beta1. Mol Cell Endocrinol 1999; 154:123-36. [PMID: 10509807 DOI: 10.1016/s0303-7207(99)00063-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The release of insulin-like growth factor binding proteins (IGFBPs) and their regulation in human glomerular endothelial cells (GENC) was characterised. GENC produce IGFBP-4, IGFBP-2 and IGFBP-3 and express mRNA for IGFBP-2 to IGFBP-5. Due to the fact that IGF-I and TGF-beta1 modulate glomerular hypertrophy, their action on IGFBP release and GENC growth was studied. IGF-I increased IGFBP-3, IGFBP-2 and decreased IGFBP-4, while TGF-beta1 decreased IGFBP-3 and apparently increased IGFBP-4. All of the IGFBPs, except the TGF-beta1-regulated IGFBP-4, were modulated at mRNA level. IGF-I stimulated GENC proliferation, while TGF-beta1 inhibited their growth. It was demonstrated that an IGFBP-3 antibody reduced GENC proliferation. However, rhIGFBP-3 alone had no effect on GENC, but after 48 h pre-incubation the IGF-I stimulated GENC growth was increased, suggesting that IGFBP-3 could modulate the IGF-I induced GENC proliferation. It was concluded that the stimulatory IGFBP-3 and the inhibitory IGFBP-4 could regulate GENC growth, although the IGFBP-3 seems to have a predominant effect in this control.
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Affiliation(s)
- S Giannini
- Department of Clinical Pathophysiology, University of Florence, Italy
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13
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Philip A, Hannah R, O'connor-McCourt M. Ectodomain cleavage and shedding of the type III transforming growth factor-beta receptor in lung membranes effect of temperature, ligand binding and membrane solubilization. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 261:618-28. [PMID: 10215877 DOI: 10.1046/j.1432-1327.1999.00298.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies from our laboratory [Philip, A. & O'Connor-McCourt, M. D. (1991) J. Biol. Chem. 266, 22290--22296] have shown that the lung exhibited the highest uptake of circulating [125I]-transforming growth factor-beta1 (TGF-beta1) on a per gram basis. This observation, together with the lack of information on TGF-beta receptor expression in the lung, prompted us to attempt to characterize TGF-beta receptors in this tissue. In the present report we show that the type III TGF-beta receptor is the most abundant TGF-beta binding protein in rat lung membranes and that it exhibits a 10-fold higher affinity for TGF-beta2 than for TGF-beta1. We observed that the majority of the type III receptor population in lung membranes is cleaved at a site in the central portion of the ectodomain, the resulting two fragments (95 kDa and 58 kDa) being held together by disulfide bonds. Furthermore, we demonstrate that a soluble form of the ectodomain of the type III receptor is shed from rat lung membranes in an efficient manner, with protease cleavage occurring at a site close to the transmembrane domain. This shedding is controllable by temperature, thus providing a system to study the mechanism of ectodomain release. Using this system, we show that the shedding is inhibited by prior ligand binding and by membrane solubilization. The identification of a membrane preparation which exhibits controllable and quantitative release of the type III receptor ectodomain provides a unique cell-free system for further studies of the mechanism of shedding of the type III TGF-beta receptor ectodomain.
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Affiliation(s)
- A Philip
- Receptor Group, Biotechnology Research Institute, National Research Council Canada, Montréal Canada
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14
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Qian SW, Dumont N, O'Connor-McCourt MD, Burmester JK. Distinct functional domains of TGF-beta bind receptors on endothelial cells. Growth Factors 1999; 17:63-73. [PMID: 10495963 DOI: 10.3109/08977199909001063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Transforming growth factor-beta (TGF-beta) is a multi-functional regulator of cell growth and differentiation. Three distinct isoforms of TGF-beta exist having similar, but not identical actions. TGF-beta 1, but not TGF-beta 2, binds to T beta RII and also to endoglin, a cell surface protein abundant on endothelial cells. In contrast, the affinity constant of TGF-beta 2 for alpha 2-macroglobulin is 10-fold greater than that of TGF-beta 1. TGF-beta 2 also binds better than TGF-beta 1 to a glycosyl phosphatidylinositol (GPI)-linked binding protein expressed on vascular endothelial cells. Using chimeric TGF-beta molecules, in which selected regions of TGF-beta 1 have been exchanged for the corresponding region of TGF-beta 2, we demonstrate here that amino acids 92-95 or 94-98 of TGF-beta determine isoform specific binding to endoglin. In contrast, exchange of only amino acids 95 and 98 did not alter TGF-beta specificity. Isoform specific binding to a GPI-linked protein on EJG endothelial cells was modulated by a region containing amino acids 40-68, although exchange of only amino acids 40-47 did not confer isoform specific binding. Significantly, the 92-98 region also modulates binding of TGF-beta to the type II receptor whereas isoform specific binding to alpha 2-macroglobulin requires concerted exchange of amino acids 45 and 47. Taken together, these results show that at least three different functional domains are important modulators of TGF-beta interaction with binding proteins and receptors.
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Affiliation(s)
- S W Qian
- Edge BioSystems, Inc., Gaithersburg, MD 20879, USA
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15
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Abstract
BACKGROUND Antiangiogenic therapy for prostatic cancer should offer additional ways of combating tumor progression. Knowledge of the possible angiogenic factors expressed by prostate cancer cell lines would therefore assist in the design and testing of such potential treatments. METHODS Changes in the proliferation and morphology of several endothelial cell lines (BAEC, HUVEC, and BACE) in response to either coculturing with human prostatic cell lines or culturing with conditioned medium derived from these lines were assessed. RESULTS Proliferation of BAEC cells was significantly stimulated by conditioned media from DU145, LNCaP, and DuPro-1, and also by coculture with LNCaP and DuPro-1. Growth of HUVEC cells was significantly increased with conditioned media from LNCaP, Ten12, and PC3, and by coculture with DU145 and DuPro-1. FGF2 supplementation is required for BACE growth in vitro, and only conditioned medium from Ten12 cells, which produce the highest levels of this growth factor, significantly increased cell numbers. BACE growth, however, was stimulated in coculture experiments with DU145, DuPro-1, PC3, and LNCaP. Morphological changes were only observed in the BAEC and BACE cells when cultured with conditioned media. CONCLUSIONS Prostatic carcinoma cell lines express a variety of angiogenic substances, including FGF2, which can stimulate endothelial cell proliferation in vitro, but this response may be modified by the prostatic-cell expression of other factors such as TGF alpha and TGF beta.
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Affiliation(s)
- P J Hepburn
- Tenovus Cancer Research Centre, University of Wales College of Medicine, Cardiff, United Kingdom
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16
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Abstract
During immune injury, activation of endothelial cells by inflammatory cytokines stimulates leukocyte adhesion to the endothelium, turns the endothelium from an anticoagulant surface to one that is frankly procoagulant, and results in the release of vasoactive mediators and growth factors. Cytokine activation of endothelial cells also results in increased endothelial cell TGF-beta 1 synthesis and enhanced activation of latent TGF-beta, the latter involving a shift of plasmin production from the apical to subendothelial surface. In cytokine-stimulated endothelial cells, TGF-beta hinders leukocyte adhesion and transmigration via inhibition of IL-8 and E-selectin expression. TGF-beta also profoundly diminishes cytokine-stimulated inducible nitric oxide synthase production and instead augments endothelial nitric oxide synthase expression. Thus, some of the TGF-beta actions on endothelium during immune activation can viewed as immunosuppressive. TGF-beta also influences mechanisms of vascular remodeling during the healing phase of immune injury. It stimulates PDGF-B synthesis by endothelial cells, causes bFGF release from subendothelial matrix, and promotes VEGF synthesis by non-endothelial cells. Together these mediators control angiogenesis, a critical component of the vascular repair phenomenon. Further, endothelial cell derived PDGF-B and bFGF influence the proliferation and migration of neighboring cells. Thus, endothelial cells and TGF-beta actions on the endothelium play important roles both during the initial phase of immune injury and during the later remodeling phase.
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Affiliation(s)
- P Pintavorn
- Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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17
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Abstract
A common feature of cancer cells is the autocrine production of growth promoters and the loss of function of tumor suppressors. In our search for such features of prostate cancer, we discovered that transforming growth factor beta 1 (TGF beta 1) levels are higher in prostate cancer than in normal prostate, and prostate cancer cells can activate endogenously-produced latent TGF beta to a bioactive form. Because TGF beta 1 is a potent growth inhibitor of epithelial cells, it seems paradoxical that malignant epithelial cells make high levels of a growth inhibitor. Even prostate cancer cells can be growth-inhibited by TGF beta 1, but only under specific conditions in vitro (plating at low cell density in serum-free medium), and this response is readily disrupted by growth factors, serum, and extracellular matrix, to all of which the cells are exposed in vivo. This explains why prostate cancer cells are resistant to the growth-inhibitory effect of TGF beta in vivo. In vivo, TGF beta 1 actually enhances prostate tumor growth and metastasis, but not by affecting tumor cell proliferation directly. One possibility is that TGF beta affects the host to allow increased numbers of tumor cells to survive and produce progeny. In addition, since prostate cancer cells can still respond to TGF beta, e.g., by increased cell motility, even under conditions that prevent growth inhibition, the ability of TGF beta to enhance tumorigenicity in vivo might also occur via direct effects on the tumor cells themselves. I will discuss new developments in our understanding of TGF beta action, which provide a framework for elucidating the mechanism by which prostate cancer cells have devised a way to protect themselves from being growth-inhibited by TGF beta 1 in vivo. Since the cells retain the ability to be growth-inhibited by TGF beta, indicating that the TGF beta receptors and signaling pathways for growth inhibition are intact, albeit inactive, it might be possible to reactivate this pathway to achieve a therapeutic benefit in vivo.
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Affiliation(s)
- E R Barrack
- Department of Urology, University School of Medicine, Baltimore, Maryland, USA
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Pepper MS. Transforming growth factor-beta: vasculogenesis, angiogenesis, and vessel wall integrity. Cytokine Growth Factor Rev 1997; 8:21-43. [PMID: 9174661 DOI: 10.1016/s1359-6101(96)00048-2] [Citation(s) in RCA: 493] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Genetic studies have recently revealed a role for transforming growth factor-beta-1 (TGF-beta 1) and its receptors (TGF-beta Rs I and II as well as endoglin) in embryonic vascular assembly and in the establishment and maintenance of vessel wall integrity. The purpose of this review is threefold: first, to reassess previous studies on TGF-beta and endothelium in the light of these recent findings; second, to describe some of the well-established as well as controversial issues concerning TGF-beta and its regulatory role in angiogenesis; and third, to explore the notion of "context' with respect to TGF-beta and endothelial cell function. Although the focus of this review will be on the endothelium, other vascular wall cells are also likely to be important in the pathogenesis of the vascular lesions revealed by genetic studies.
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Affiliation(s)
- M S Pepper
- Department of Morphology, University of Geneva Medical Center, Switzerland.
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