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Abstract
The reproducible pattern of blood vessels formed in vertebrate embryos has been described extensively, but only recently have we obtained the genetic and molecular tools to address the mechanisms underlying these processes. This review describes our current knowledge regarding vascular patterning around the vertebrate midline and presents data derived from frogs, zebrafish, avians, and mice. The embryonic structures implicated in midline vascular patterning, the hypochord, endoderm, notochord, and neural tube, are discussed. Moreover, several molecular signaling pathways implicated in vascular patterning, VEGF, Tie/tek, Notch, Eph/ephrin, and Semaphorin, are described. Data showing that VEGF is critical to patterning the dorsal aorta in frogs and zebrafish, and to patterning the vascular plexus that forms around the neural tube in amniotes, is presented. A more complete knowledge of vascular patterning is likely to come from the next generation of experiments using ever more sophisticated tools, and these results promise to directly impact on clinically important issues such as forming new vessels in the human body and/or in bioreactors.
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Affiliation(s)
- Kelly A Hogan
- Department of Biology, University of North Carolina at Chapel Hill, 27599, USA
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252
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Lambrechts D, Carmeliet P. Genetics in zebrafish, mice, and humans to dissect congenital heart disease: insights in the role of VEGF. Curr Top Dev Biol 2004; 62:189-224. [PMID: 15522743 DOI: 10.1016/s0070-2153(04)62007-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Heart development and the establishment of a functional circulatory circuit are complex biological processes in which subtle perturbations may result in catastrophic consequences of cardiovascular birth defects. Studies in model organisms, most notably the mouse and the zebrafish, have identified genes that also cause these life-threatening defects when mutated in humans. Gradually, a framework for the genetic pathway controlling these events is now beginning to emerge. However, the puzzling phenotypic variability of the cardiovascular disease phenotype in humans and the recent identification of phenotypic modifiers using model organisms indicates that other genetic loci might interact to modify the disease phenotype. To illustrate this, we review the role of vascular endothelial growth factor (VEGF) during vascular and cardiac development and stress how zebrafish and mouse genetic studies have helped us to understand the role this growth factor has in human disease, in particular in the Di-George syndrome.
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Affiliation(s)
- Diether Lambrechts
- Flanders Interuniversity Institute for Biotechnology, Center for Transgene Technology and Gene Therapy, KU Leuven, Leuven, B-3000, Belgium
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253
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Landles C, Chalk S, Steel JH, Rosewell I, Spencer-Dene B, Lalani EN, Parker MG. The Thyroid Hormone Receptor-Associated Protein TRAP220 Is Required at Distinct Embryonic Stages in Placental, Cardiac, and Hepatic Development. Mol Endocrinol 2003; 17:2418-35. [PMID: 14500757 DOI: 10.1210/me.2003-0097] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
AbstractRecent work indicates that thyroid hormone receptor-associated protein 220 (TRAP220), a subunit of the multiprotein TRAP coactivator complex, is essential for embryonic survival. We have generated TRAP220 conditional null mice that are hypomorphic and express the gene at reduced levels. In contrast to TRAP220 null mice, which die at embryonic d 11.5 (E11.5), hypomorphic mice survive until E13.5. The reduced expression in hypomorphs results in hepatic necrosis, defects in hematopoiesis, and hypoplasia of the ventricular myocardium, similar to that observed in TRAP220 null embryos at an earlier stage. The embryonic lethality of null embryos at E11.5 is due to placental insufficiency. Tetraploid aggregation assays partially rescues embryonic development until E13.5, when embryonic loss occurs due to hepatic necrosis coupled with poor myocardial development as observed in hypomorphs. These findings demonstrate that, for normal placental function, there is an absolute requirement for TRAP220 in extraembryonic tissues at E11.5, with an additional requirement in embryonic tissues for hepatic and cardiovascular development thereafter.
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Affiliation(s)
- Christian Landles
- Institute of Reproductive and Developmental Biology, Imperial College, Faculty of Medicine, Du Cane Road, London W12 ONN, United Kingdom
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254
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Madri JA, Enciso J, Pinter E. Maternal diabetes: effects on embryonic vascular development--a vascular endothelial growth factor-A-mediated process. Pediatr Dev Pathol 2003; 6:334-41. [PMID: 14692647 DOI: 10.1007/s10024-003-5051-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Major congenital malformations, many of which result from abnormal cardiovascular patterning, remain the leading cause in infant mortality and morbidity. Targeted mutations of several genes (including VEGF and VEGF receptors) and certain teratogenic agents (including excess alpha-D-glucose) give rise to embryonic lethal phenotypes associated with failure in the formation of a functional vitelline circulation and aberrant organogenesis. Our work to date has demonstrated that yolk sac vasculopathy and failure of endocardial cushion epithelial-mesenchymal transformation occurs in hyperglycemic conditions in murine whole conceptus culture and in embryos from streptozotocin-induced diabetic mice. These cardiovascular abnormalities are associated with changes in expression and phosphorylation state of adhesion molecules such as platelet endothelial growth factor-1 and expression of growth factors such as vascular endothelial growth factor (VEGF-A). Further understanding of the effects of maternal diabetes on yolk sac and embryonic vasculogenesis/angiogenesis and organogenesis may lead to novel approaches in treating and preventing major birth defects.
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Affiliation(s)
- Joseph A Madri
- Department of Pathology, Yale University School of Medicine, 310 Cedar Street, P.O. Box 208023, New Haven, CT 06520-8023, USA.
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255
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Abstract
The vasculature is one of the most important and complex organs in the mammalian body. The first functional organ to form during embryonic development, the intricately branched network of endothelial and supporting periendothelial cells is essential for the transportation of oxygen and nutrients to and the removal of waste products from the tissues. Serious disruptions in the formation of the vascular network are lethal early in post-implantation development, while the maintenance of vessel integrity and the control of vessel physiology and hemodynamics have important consequences throughout embryonic and adult life. A full understanding of the signaling pathways of vascular development is important not just for understanding normal development but because of the importance of reactivation of angiogenic pathways in disease states. Clinically there is a need to develop therapies to promote new blood vessel formation in situations of severe tissue ischemia, such as coronary heart disease. In addition, there is considerable interest in developing angiogenic inhibitors to block the new vessel growth that solid tumors promote in host tissue to enhance their own growth. Already studies on the signaling pathways of normal vascular development have provided new targets for therapeutic intervention in both situations. Further understanding of the complexities of the pathways should help refine such strategies.
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Affiliation(s)
- Janet Rossant
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital and Department of Molecular and Medical Genetics, University of Toronto, 600 University Avenue, Ontario, M5G 1X5, Canada.
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256
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Finkelstein EB, Poole TJ. Vascular endothelial growth factor: a regulator of vascular morphogenesis in the Japanese quail embryo. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2003; 272:403-14. [PMID: 12704698 DOI: 10.1002/ar.a.10047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Experiments in mouse embryos indicate that a critical level of VEGF is required for normal vascular development, as mice lacking a single VEGF allele die at midgestation. Thus VEGF concentration may be a determinant of the size and location of major blood vessels during formation of the primary capillary plexus. Ectopic VEGF delivery was used to examine the effect of VEGF concentration on early vascular patterning in the quail embryo. VEGF was delivered by implanting VEGF-soaked heparin chromatography beads at three rostral-caudal locations in embryos with six somite pairs, which allowed us to study the effect of VEGF on different cellular activities. Ectopic VEGF resulted in significant changes in the vascular pattern at three rostral-caudal levels. Quantitation demonstrated an increased vascularity in the area of the implanted VEGF bead compared to the vascular pattern of embryos with control beads. Areas lateral to the dorsal aortae that are normally avascular became vascularized, and there was an apparent fusion between the dorsal aorta and lateral capillary plexus.
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Affiliation(s)
- Eric B Finkelstein
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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257
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Dor Y, Klewer SE, McDonald JA, Keshet E, Camenisch TD. VEGF modulates early heart valve formation. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2003; 271:202-8. [PMID: 12552636 DOI: 10.1002/ar.a.10026] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although hypoxic and/or nutritional insults during gestation are believed to contribute to congenital heart defects, the mechanisms responsible for these anomalies are not understood. Given the role vascular endothelial growth factor (VEGF) plays in response to hypoxia, it is a likely candidate for mediating deleterious effects of embryonic hypoxia. The ectopic or overproduction of endogenous factors such as VEGF may contribute to specific heart defects. Here we compared hypoxia-induced precocious production of VEGF during early heart valve development to normal VEGF production. Mouse prevalvular cardiac endocardial cushions were explanted onto hydrated type I collagen gels under normoxic or hypoxic conditions. The extent of transformation of cardiac endothelium into mesenchyme was inversely correlated with the levels of VEGF during the various culture conditions. A soluble VEGF antagonist confirmed that endogenous production of VEGF was specific for blocking normal cushion mesenchyme formation. We further demonstrated that E10.5 endocardium retains the ability to transform into cardiac mesenchyme in the absence of endogenous VEGF.
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Affiliation(s)
- Yuval Dor
- Department of Molecular Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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258
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Enciso JM, Gratzinger D, Camenisch TD, Canosa S, Pinter E, Madri JA. Elevated glucose inhibits VEGF-A-mediated endocardial cushion formation: modulation by PECAM-1 and MMP-2. J Cell Biol 2003; 160:605-15. [PMID: 12591918 PMCID: PMC2173755 DOI: 10.1083/jcb.200209014] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Atrioventricular (AV) septal defects resulting from aberrant endocardial cushion (EC) formation are observed at increased rates in infants of diabetic mothers. EC formation occurs via an epithelial-mesenchymal transformation (EMT), involving transformation of endocardial cells into mesenchymal cells, migration, and invasion into extracellular matrix. Here, we report that elevated glucose inhibits EMT by reducing myocardial vascular endothelial growth factor A (VEGF-A). This effect is reversed with exogenous recombinant mouse VEGF-A165, whereas addition of soluble VEGF receptor-1 blocks EMT. We show that disruption of EMT is associated with persistence of platelet endothelial cell adhesion molecule-1 (PECAM-1) and decreased matrix metalloproteinase-2 (MMP-2) expression. These findings correlate with retention of a nontransformed endocardial sheet and lack of invasion. The MMP inhibitor GM6001 blocks invasion, whereas explants from PECAM-1 deficient mice exhibit MMP-2 induction and normal EMT in high glucose. PECAM-1-negative endothelial cells are highly motile and express more MMP-2 than do PECAM-1-positive endothelial cells. During EMT, loss of PECAM-1 similarly promotes single cell motility and MMP-2 expression. Our findings suggest that high glucose-induced inhibition of AV cushion morphogenesis results from decreased myocardial VEGF-A expression and is, in part, mediated by persistent endocardial cell PECAM-1 expression and failure to up-regulate MMP-2 expression.
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Affiliation(s)
- Josephine M Enciso
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520-8023, USA
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259
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Drake CJ. Embryonic and adult vasculogenesis. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2003; 69:73-82. [PMID: 12768659 DOI: 10.1002/bdrc.10003] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Two mechanisms account for the formation of blood vessels, vasculogenesis and angiogenesis. Unfortunately, the terms vasculogenesis and angiogenesis literally have the same meaning, i.e., the genesis of blood vessels, and thus do little to distinguish between the two processes. Despite the nomenclature, the two processes are clearly distinct. Vasculogenesis, the de novo formation of blood vessels from mesoderm, is driven by the recruitment of undifferentiated mesodermal cells to the endothelial lineage and the de novo assembly of such cells into blood vessels. Angiogenesis is the generation of new blood vessels from endothelial cells of existing blood vessels, a process driven by endothelial cell proliferation. Recent years have seen dramatic changes in our understanding of the process of vasculogenesis, expanding the scope of its occurrence beyond the earliest stages of development to include involvement in neovascular processes throughout development as well as in the adult. In this review, emphasis is placed on discussion of emerging perspectives on the process of vasculogenesis in both the embryo and the adult.
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Affiliation(s)
- Christopher J Drake
- Cardiovascular Developmental Biology Center, Department of Cell Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA.
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260
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Johnson EN, Lee YM, Sander TL, Rabkin E, Schoen FJ, Kaushal S, Bischoff J. NFATc1 mediates vascular endothelial growth factor-induced proliferation of human pulmonary valve endothelial cells. J Biol Chem 2003; 278:1686-92. [PMID: 12427739 PMCID: PMC2813494 DOI: 10.1074/jbc.m210250200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mice deficient for the transcription factor NFATc1 fail to form pulmonary and aortic valves, a defect reminiscent of some types of congenital human heart disease. We examined the mechanisms by which NFATc1 is activated and translocated to the nucleus in human pulmonary valve endothelial cells to gain a better understanding of its potential role(s) in post-natal valvular repair as well as valve development. Herein we demonstrate that activation of NFATc1 in human pulmonary valve endothelial cells is specific to vascular endothelial growth factor (VEGF) signaling through VEGF receptor 2. VEGF-induced NFATc1 nuclear translocation was inhibited by either cyclosporin A or a calcineurin-specific peptide inhibitor; these findings suggest that VEGF stimulates NFATc1 nuclear import in human pulmonary valve endothelial cells by a calcineurin-dependent mechanism. Importantly, both cyclosporin A and the calcineurin-specific peptide inhibitor reduced VEGF-induced human pulmonary valve endothelial cell proliferation, indicating a functional role for NFATc1 in endothelial growth. In contrast, VEGF-induced proliferation of human dermal microvascular and human umbilical vein endothelial cells was not sensitive to cyclosporin A. Finally, NFATc1 was detected in the endothelium of human pulmonary valve leaflets by immunohistochemistry. These results suggest VEGF-induced NFATc1 activation may be an important mechanism in cardiac valve maintenance and function by enhancing endothelial proliferation.
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Affiliation(s)
- Ehrin N. Johnson
- Department of Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - You Mie Lee
- Department of Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Tara L. Sander
- Department of Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Elena Rabkin
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Frederick J. Schoen
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | | | - Joyce Bischoff
- Department of Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts 02115
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261
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Sohn SJ, Sarvis BK, Cado D, Winoto A. ERK5 MAPK regulates embryonic angiogenesis and acts as a hypoxia-sensitive repressor of vascular endothelial growth factor expression. J Biol Chem 2002; 277:43344-51. [PMID: 12221099 DOI: 10.1074/jbc.m207573200] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During angiogenesis, endothelial cells undergo proliferation, reorganization, and stabilization to establish a mature vascular network. This process is critical for establishing a functional circulatory system during development and contributes to the pathological process of tumor growth. Here we report that embryos deficient for the ERK5 MAPK die between embryonic days 10.5 and 11.5 with angiogenic failure and cardiovascular defects. We show that ERK5 deficiency leads to an increased expression of the vascular endothelial growth factor (VEGF), dysregulation of which has been shown to impede angiogenic remodeling and vascular stabilization. Our data also reveal that ERK5 negatively regulates transcription from the vegf locus during hypoxic responses. Importantly, ERK5 is required at an earlier developmental stage than p38alpha, and p38alpha does not compensate for ERK5 deficiency. These results demonstrate that ERK5 plays a specific role in the regulation of early angiogenesis.
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Affiliation(s)
- Sue J Sohn
- Department of Molecular and Cell Biology, Division of Immunology and Cancer Research Laboratory, University of California, Berkeley, California 94720-3200, USA
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262
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Ruhrberg C, Gerhardt H, Golding M, Watson R, Ioannidou S, Fujisawa H, Betsholtz C, Shima DT. Spatially restricted patterning cues provided by heparin-binding VEGF-A control blood vessel branching morphogenesis. Genes Dev 2002; 16:2684-98. [PMID: 12381667 PMCID: PMC187458 DOI: 10.1101/gad.242002] [Citation(s) in RCA: 635] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Branching morphogenesis in the mammalian lung and Drosophila trachea relies on the precise localization of secreted modulators of epithelial growth to select branch sites and direct branch elongation, but the intercellular signals that control blood vessel branching have not been previously identified. We found that VEGF(120/120) mouse embryos, engineered to express solely an isoform of VEGF-A that lacks heparin-binding, and therefore extracellular matrix interaction domains, exhibited a specific decrease in capillary branch formation. This defect was not caused by isoform-specific differences in stimulating endothelial cell proliferation or by impaired isoform-specific signaling through the Nrp1 receptor. Rather, changes in the extracellular localization of VEGF-A in heparin-binding mutant embryos resulted in an altered distribution of endothelial cells within the growing vasculature. Instead of being recruited into additional branches, nascent endothelial cells were preferentially integrated within existing vessels to increase lumen caliber. The disruption of the normal VEGF-A concentration gradient also impaired the directed extension of endothelial cell filopodia, suggesting that heparin-binding VEGF-A isoforms normally provide spatially restricted stimulatory cues that polarize and thereby guide sprouting endothelial cells to initiate vascular branch formation. Consistent with this idea, we found opposing defects in embryos harboring only a heparin-binding isoform of VEGF-A, including excess endothelial filopodia and abnormally thin vessel branches in ectopic sites. We conclude that differential VEGF-A isoform localization in the extracellular space provides a control point for regulating vascular branching pattern.
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Affiliation(s)
- Christiana Ruhrberg
- Endothelial Cell Biology Laboratory, Cancer Research UK London Research Institute, London WC2A 3PX, United Kingdom
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263
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Muñoz-Chápuli R, Macías D, González-Iriarte M, Carmona R, Atencia G, Pérez-Pomares JM. [The epicardium and epicardial-derived cells: multiple functions in cardiac development]. Rev Esp Cardiol 2002; 55:1070-82. [PMID: 12383393 DOI: 10.1016/s0300-8932(02)76758-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The epicardium develops from an extracardiac primordium, the proepicardium, which is constituted by a cluster of mesothelial cells located on the cephalic and ventral surface of the liver-sinus venosus limit (avian embryos) or on the pericardial side of the septum transversum (mammalian embryos). The proepicardium contacts the myocardial surface and gives rise to a mesothelium, which grows and progressively lines the myocardium. The epicardium generates, through a process of epithelial-mesenchymal transition, a population of epicardial-derived cells (EPDC). EPDC contribute to the development of cardiac connective tissue, fibroblasts, and the smooth muscle of cardiac vessels. Recent data suggest that EPDC can also differentiate into endothelial cells of the primary subepicardial vascular plexus. If this is confirmed, EPDC would show the same developmental properties that characterize the stem-cell-derived bipotential vascular progenitors recently described, whose differentiation into endothelium and smooth muscle is regulated by exposure to VEGF and PDGF-BB, respectively. Aside from their function in the development of cardiac connective and vascular tissue, EPDC also play an essential modulating role in the differentiation of the compact ventricular layer of the myocardium, a role which might be regulated by the transcription factor WT1 and the production of retinoic acid.
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Affiliation(s)
- Ramón Muñoz-Chápuli
- Departamento de Biología Animal. Facultad de Ciencias. Universidad de Málaga. España.
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264
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Peng H, Wright V, Usas A, Gearhart B, Shen HC, Cummins J, Huard J. Synergistic enhancement of bone formation and healing by stem cell-expressed VEGF and bone morphogenetic protein-4. J Clin Invest 2002; 110:751-9. [PMID: 12235106 PMCID: PMC151123 DOI: 10.1172/jci15153] [Citation(s) in RCA: 569] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We investigated the interaction between angiogenic and osteogenic factors in bone formation and bone healing with ex vivo gene therapy using muscle-derived stem cells genetically engineered to express human bone morphogenetic protein-4 (BMP4), VEGF, or VEGF-specific antagonist (soluble Flt1). Our results show that although VEGF alone did not improve bone regeneration, it acted synergistically with BMP4 to increase recruitment of mesenchymal stem cells, to enhance cell survival, and to augment cartilage formation in the early stages of endochondral bone formation. These early effects, coupled with accelerated cartilage resorption, eventually led to a significant enhancement of bone formation and bone healing. The beneficial effect of VEGF on bone healing elicited by BMP4 depends critically on the ratio of VEGF to BMP4, with an improper ratio leading to detrimental effects on bone healing. Finally, we show that soluble Flt1 inhibits bone formation elicited by BMP4. Thus, VEGF plays an important role in bone formation elicited by BMP4, and it can significantly enhance BMP4-elicited bone formation and regeneration through multiple mechanisms. This study has important implications for the formulation of new strategies to improve bone healing through increasing mesenchymal stem cell recruitment and survival, in combination with muscle-derived stem cell-based gene therapy.
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Affiliation(s)
- Hairong Peng
- Growth and Development Laboratory, Department of Orthopaedic Surgery, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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265
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Yin Z, Haynie J, Yang X, Han B, Kiatchoosakun S, Restivo J, Yuan S, Prabhakar NR, Herrup K, Conlon RA, Hoit BD, Watanabe M, Yang YC. The essential role of Cited2, a negative regulator for HIF-1alpha, in heart development and neurulation. Proc Natl Acad Sci U S A 2002; 99:10488-93. [PMID: 12149478 PMCID: PMC124951 DOI: 10.1073/pnas.162371799] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cited2 is a cAMP-responsive element-binding protein (CBP)/p300 interacting transcriptional modulator and a proposed negative regulator for hypoxia-inducible factor (HIF)-1alpha through its competitive binding with HIF-1alpha to CBP/p300. Disruption of the gene encoding Cited2 is embryonic lethal because of defects in the development of heart and neural tube. Morphological and Doppler echocardiographic analyses of Cited2(-/-) embryos reveal severe cardiovascular abnormalities, including pulmonic arterial stenosis and ventricular septal defects accompanied by high peak outflow velocities, features of the human congenital cardiac defect termed tetralogy of Fallot. The mRNA levels of several HIF-1alpha-responsive genes, such as vascular endothelial growth factor (VEGF), Glut1, and phosphoglycerate kinase 1, increased in the Cited2(-/-) hearts. The increase of VEGF levels is significant, because defects in the Cited2(-/-) embryos closely resemble the major defects observed in the VEGF transgenic embryos. Finally, compared with wild-type, cultured fibroblasts from Cited2(-/-) embryos demonstrate an enhanced expression of HIF-1alpha-responsive genes under hypoxic conditions. These observations suggest that functional loss of Cited2 is responsible for defects in heart and neural tube development, in part because of the modulation of HIF-1 transcriptional activities in the absence of Cited2. These findings demonstrate that Cited2 is an indispensable regulatory gene during prenatal development.
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Affiliation(s)
- Zhan Yin
- Department of Pharmacology and Cancer Center, University Hospitals of Cleveland, OH 44106-4965, USA
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266
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Rouwet EV, Tintu AN, Schellings MWM, van Bilsen M, Lutgens E, Hofstra L, Slaaf DW, Ramsay G, Le Noble FAC. Hypoxia induces aortic hypertrophic growth, left ventricular dysfunction, and sympathetic hyperinnervation of peripheral arteries in the chick embryo. Circulation 2002; 105:2791-6. [PMID: 12057996 DOI: 10.1161/01.cir.0000017497.47084.06] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Low birth weight is associated with an increased incidence of cardiovascular diseases, including hypertension, later in life. This suggests that antenatal insults program for fetal adaptations of the circulatory system. In the present study, we evaluated the effects of mild hypoxia on cardiac function, blood pressure control, and arterial structure and function in near-term chick embryos. METHODS AND RESULTS Chick embryos were incubated under normoxic (21% O2) or hypoxic (15% O2) conditions and evaluated at incubation day 19 by use of histological techniques, isolated heart preparations, and in vivo measurements of sympathetic arterial tone and systemic hemodynamics. Chronic hypoxia caused a 33% increase in mortality and an 11% reduction in body weight in surviving embryos. The lumen of the ascending aorta in hypoxic embryos was 23% smaller. Left ventricular systolic pressure was 22% lower, and heart weight/body weight ratio was 14% higher. In resistance arteries of hypoxic embryos, in vivo baseline tone was 23% higher, norepinephrine sensitivity was similar, and norepinephrine release from sympathetic nerves increased 2-fold, indicating sympathetic hyperinnervation. Mean arterial pressure and heart rate were similar under resting conditions, but chronically hypoxic embryos failed to maintain blood pressure during acute stress. CONCLUSIONS This study indicates that mild hypoxia during embryonic development induces alterations in cardiac and vascular function and structure and affects hemodynamic regulation. These findings reveal that antenatal insults have profound effects on the control and design of the circulatory system that are already established at birth and may program for hypertension and heart failure at a later age.
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Affiliation(s)
- E V Rouwet
- Departments of Surgery, Cardiovascular Research Institute, Maastricht, Netherlands
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267
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Abstract
With the advent of molecular embryology and exploitation of genetic models systems, many genes necessary for normal blood vessel formation during early development have been identified. These genes include soluble effectors and their receptors, as well as components of cell-cell junctions and mediators of cell-matrix interactions. In vitro model systems (2-D and 3-D) to study paracrine and autocrine interactions of vascular cells and their progenitors have also been created. These systems are being combined to study the behavior of genetically altered cells to dissect and define the cellular role(s) of specific genes and gene families in directing the migration, proliferation, and differentiation needed for blood vessel assembly. It is clear that a complex spatial and temporal interplay of signals, including both genetic and environmental, modulates the assembly process. The development of real-time imaging and image analysis will enable us to gain further insights into this process. Collaborative efforts among vascular biologists, biomedical engineers, mathematicians, and physicists will allow us to bridge the gap between understanding vessel assembly in vivo and assembling vessels ex vivo.
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Affiliation(s)
- Karen K Hirschi
- Departments of Pediatrics and Molecular & Cellular Biology, Baylor College of Medicine, One Baylor Plaza, N1030, Houston, TX 77030, USA.
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268
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Kearney JB, Ambler CA, Monaco KA, Johnson N, Rapoport RG, Bautch VL. Vascular endothelial growth factor receptor Flt-1 negatively regulates developmental blood vessel formation by modulating endothelial cell division. Blood 2002; 99:2397-407. [PMID: 11895772 DOI: 10.1182/blood.v99.7.2397] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mice lacking the vascular endothelial growth factor (VEGF) receptor flt-1 die of vascular overgrowth, and we are interested in how flt-1 normally prevents this outcome. Our results support a model whereby aberrant endothelial cell division is the cellular mechanism resulting in vascular overgrowth, and they suggest that VEGF-dependent endothelial cell division is normally finely modulated by flt-1 to produce blood vessels. Flt-1(-/-) embryonic stem cell cultures had a 2-fold increase in endothelial cells by day 8, and the endothelial cell mitotic index was significantly elevated before day 8. Flt-1 mutant embryos also had an increased endothelial cell mitotic index, indicating that aberrant endothelial cell division occurs in vivo in the absence of flt-1. The flt-1 mutant vasculature of the cultures was partially rescued by mitomycin C treatment, consistent with a cell division defect in the mutant background. Analysis of cultures at earlier time points showed no significant differences until day 5, when flt-1 mutant cultures had increased beta-galactosidase(+) cells, indicating that the expansion of flt-1 responsive cells occurs after day 4. Mitomycin C treatment blocked this early expansion, suggesting that aberrant division of angioblasts and/or endothelial cells is a hallmark of the flt-1 mutant phenotype throughout vascular development. Consistent with this model is the finding that expansion of platelet and endothelial cell adhesion molecule(+) and VE-cadherin(+) vascular cells in the flt-1 mutant background first occurs between day 5 and day 6. Taken together, these data show that flt-1 normally modulates vascular growth by controlling the rate of endothelial cell division both in vitro and in vivo.
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Affiliation(s)
- Joseph B Kearney
- Program in Genetics and Molecular Biology, Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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269
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Crawford SE, Qi C, Misra P, Stellmach V, Rao MS, Engel JD, Zhu Y, Reddy JK. Defects of the heart, eye, and megakaryocytes in peroxisome proliferator activator receptor-binding protein (PBP) null embryos implicate GATA family of transcription factors. J Biol Chem 2002; 277:3585-92. [PMID: 11724781 DOI: 10.1074/jbc.m107995200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Peroxisome proliferator activator receptor (PPAR)-binding protein (PBP) is an important coactivator for PPARgamma and other nuclear receptors. It has been identified as an integral component of a multiprotein thyroid hormone receptor-associated protein/vitamin D(3) receptor-interacting protein/activator-recruited cofactor complexes required for transcriptional activity. Here, we show that PBP is critical for the development of placenta and for the normal embryonic development of the heart, eye, vascular, and hematopoietic systems. The primary functional cause of embryonic lethality at embryonic day11.5 observed with PBP null mutation was cardiac failure because of noncompaction of the ventricular myocardium and resultant ventricular dilatation. There was a paucity of retinal pigment, defective lens formation, excessive systemic angiogenesis, a deficiency in the number of megakaryocytes, and an arrest in erythrocytic differentiation. Some of these defects involve PPARgamma and retinoid-sensitive sites, whereas others have not been recognized in the PPAR-signaling pathway. Phenotypic changes in four organ systems observed in PBP null mice overlapped with those in mice deficient in members of GATA, a family of transcription factors known to regulate differentiation of megakaryocytes, erythrocytes, and adipocytes. We demonstrate that PBP interacts with all five GATA factors analyzed, GATA-1, GATA-2, GATA-3, GATA-4, and GATA-6, and show that the binding of GATA-1, GATA-4, and GATA-6 to PBP is not dependent on the nuclear receptor recognition sequence motif LXXLL (where L is leucine and X is any amino acid) in PBP. Coexpression of PBP with GATA-3 markedly enhanced transcriptional activity of GATA-3 in nonhematopoietic cells. These observations identify the GATA family of transcription factors as a new interacting partner of PBP and demonstrate that PBP is essential for normal development of vital organ systems.
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Affiliation(s)
- Susan E Crawford
- Department of Pathology, Northwestern University School of Medicine, Chicago, Illinois 60611-3008, USA
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270
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Abstract
Angiogenesis is a key event in a broad range of pathological conditions including both diseases with an enhanced and insufficient angiogenesis. Angiogenesis is often initiated with vasodilation accompanied by an increase in vascular permeability. After destabilization of the vessel wall and degradation of the surrounding extracellular matrix, extravasation of plasma proteins provides a provisional scaffold for the migration of endothelial cells. Endothelial cell proliferation and migration themselves are under tight control by a balance of angiogenesis inducers and inhibitors. A large number of angiogenic factors work together in a highly coordinated manner to induce endothelial cell outgrowth and the formation of functional vessels. On the other hand, angiostatic factors may play a critical role in the pathogenesis of ischemic diseases and contribute to the termination of physiological angiogenesis. Angiogenesis ends with the recruitment of pericytes and smooth muscle cells, which stabilize the newly formed vessel. The rapid increase in the knowledge about the molecular mechanisms of angiogenesis has led to first treatment trials in diseases with both enhanced and reduced angiogenesis. Although initial results are promising, much more work has to be done to consider anti-angiogenic or pro-angiogenic approaches as reliable therapeutic tools.
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Affiliation(s)
- Oliver Distler
- WHO Collaborating Center for Molecular Biology and Novel Therapeutic Strategies for Rheumatic Diseases, University Hospital Zurich, CH-8091, Switzerland.
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271
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Liang D, Chang JR, Chin AJ, Smith A, Kelly C, Weinberg ES, Ge R. The role of vascular endothelial growth factor (VEGF) in vasculogenesis, angiogenesis, and hematopoiesis in zebrafish development. Mech Dev 2001; 108:29-43. [PMID: 11578859 DOI: 10.1016/s0925-4773(01)00468-3] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Vascular endothelial growth factor (VEGF, VEGF-A), a selective mitogen for endothelial cells is a critical factor for vascular development. Two isoforms that differ in the presence of exons 6 and 7, Vegf(165) and Vegf(121), are the dominant forms expressed in zebrafish embryo. Simultaneous overexpression of both isoforms in the embryo results in increased production of flk1, tie1, scl, and gata1 transcripts, indicating a stimulation of both endothelial and hematopoietic lineages. We also demonstrate that vegf can stimulate hematopoiesis in zebrafish by promoting the formation of terminally differentiated red blood cells. Simultaneous overexpression of both isoforms also causes ectopic vasculature and blood cells in many of the injected embryos as well as pericardial edema in later stage embryos. Overexpression of vegf also resulted in earlier onset of flk1, tie1, scl, and gata1 expression in the embryo, indicating a possible role of vegf in stimulating the differentiation of both vascular and hematopoietic lineages. Co-injection of RNAs for both isoforms results in increased expression of three of these markers over and above that observed when either RNA is singly injected and analysis of vegf expression in the notochord mutants no tail and floating head suggests that the notochord patterns the formation of the dorsal aorta by stimulating adjacent somite cells to express vegf, which in turn functions as a signal in dorsal aorta patterning. Finally, studies of vegf expression in cloche mutant indicate that vegf expression is generally independent of cloche function. These results show that in the zebrafish embryo, vegf can not only stimulate endothelial cell differentiation but also hematopoiesis. Moreover, these effects are most dramatic when both vegf isoforms are co-expressed, indicating a synergistic effect of the expression of the two forms of the VEGF protein.
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Affiliation(s)
- D Liang
- Department of Biological Sciences, National University of Singapore, Singapore 119260
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272
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Dor Y, Camenisch TD, Itin A, Fishman GI, McDonald JA, Carmeliet P, Keshet E. A novel role for VEGF in endocardial cushion formation and its potential contribution to congenital heart defects. Development 2001; 128:1531-8. [PMID: 11290292 DOI: 10.1242/dev.128.9.1531] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Normal cardiovascular development is exquisitely dependent on the correct dosage of the angiogenic growth factor and vascular morphogen vascular endothelial growth factor (VEGF). However, cardiac expression of VEGF is also robustly augmented during hypoxic insults, potentially mediating the well-established teratogenic effects of hypoxia on heart development. We report that during normal heart morphogenesis VEGF is specifically upregulated in the atrioventricular (AV) field of the heart tube soon after the onset of endocardial cushion formation (i.e. the endocardium-derived structures that build the heart septa and valves). To model hypoxia-dependent induction of VEGF in vivo, we conditionally induced VEGF expression in the myocardium using a tetracycline-regulated transgenic system. Premature induction of myocardial VEGF in E9.5 embryos to levels comparable with those induced by hypoxia prevented formation of endocardial cushions. When added to explanted embryonic AV tissue, VEGF fully inhibited endocardial-to-mesenchymal transformation. Transformation was also abrogated in AV explants subjected to experimental hypoxia but fully restored in the presence of an inhibitory soluble VEGF receptor 1 chimeric protein. Together, these results suggest a novel developmental role for VEGF as a negative regulator of endocardial-to-mesenchymal transformation that underlies the formation of endocardial cushions. Moreover, ischemia-induced VEGF may be the molecular link between hypoxia and congenital defects in heart septation.
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Affiliation(s)
- Y Dor
- Department of Molecular Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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273
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Hellström M, Gerhardt H, Kalén M, Li X, Eriksson U, Wolburg H, Betsholtz C. Lack of pericytes leads to endothelial hyperplasia and abnormal vascular morphogenesis. J Cell Biol 2001; 153:543-53. [PMID: 11331305 PMCID: PMC2190573 DOI: 10.1083/jcb.153.3.543] [Citation(s) in RCA: 766] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The association of pericytes (PCs) to newly formed blood vessels has been suggested to regulate endothelial cell (EC) proliferation, survival, migration, differentiation, and vascular branching. Here, we addressed these issues using PDGF-B-- and PDGF receptor-beta (PDGFR-beta)--deficient mice as in vivo models of brain angiogenesis in the absence of PCs. Quantitative morphological analysis showed that these mutants have normal microvessel density, length, and number of branch points. However, absence of PCs correlates with endothelial hyperplasia, increased capillary diameter, abnormal EC shape and ultrastructure, changed cellular distribution of certain junctional proteins, and morphological signs of increased transendothelial permeability. Brain endothelial hyperplasia was observed already at embryonic day (E) 11.5 and persisted throughout development. From E 13.5, vascular endothelial growth factor-A (VEGF-A) and other genes responsive to metabolic stress became upregulated, suggesting that the abnormal microvessel architecture has systemic metabolic consequences. VEGF-A upregulation correlated temporally with the occurrence of vascular abnormalities in the placenta and dilation of the heart. Thus, although PC deficiency appears to have direct effects on EC number before E 13.5, the subsequent increased VEGF-A levels may further abrogate microvessel architecture, promote vascular permeability, and contribute to formation of the edematous phenotype observed in late gestation PDGF-B and PDGFR-beta knock out embryos.
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Affiliation(s)
- Mats Hellström
- Department of Medical Biochemistry, Göteborg University, SE-405 30 Göteborg, Sweden
- Ludwig Institute for Cancer Research, Stockholm Branch, Karolinska Institute, SE-171 77 Stockholm, Sweden
| | - Holger Gerhardt
- Department of Medical Biochemistry, Göteborg University, SE-405 30 Göteborg, Sweden
- Institute of Pathology, University of Tuebingen, 72076 Tuebingen, Germany
| | - Mattias Kalén
- Department of Medical Biochemistry, Göteborg University, SE-405 30 Göteborg, Sweden
| | - Xuri Li
- Ludwig Institute for Cancer Research, Stockholm Branch, Karolinska Institute, SE-171 77 Stockholm, Sweden
| | - Ulf Eriksson
- Ludwig Institute for Cancer Research, Stockholm Branch, Karolinska Institute, SE-171 77 Stockholm, Sweden
| | - Hartwig Wolburg
- Institute of Pathology, University of Tuebingen, 72076 Tuebingen, Germany
| | - Christer Betsholtz
- Department of Medical Biochemistry, Göteborg University, SE-405 30 Göteborg, Sweden
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274
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Affiliation(s)
- L E Benjamin
- Depatrtment of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School. 300 Brookline Ave., Boston, MA 02215, USA.
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275
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Pinter E, Haigh J, Nagy A, Madri JA. Hyperglycemia-induced vasculopathy in the murine conceptus is mediated via reductions of VEGF-A expression and VEGF receptor activation. THE AMERICAN JOURNAL OF PATHOLOGY 2001; 158:1199-206. [PMID: 11290536 PMCID: PMC1891927 DOI: 10.1016/s0002-9440(10)64069-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Major congenital malformations, including those affecting the cardiovascular system, remain the leading cause of mortality and morbidity in infants of diabetic mothers. Interestingly, targeted mutations of several genes (including VEGF and VEGF receptors) and many teratogenic agents (including excess D-glucose) that give rise to embryonic lethal phenotypes during organogenesis are associated with a failure in the formation and/or maintenance of a functional vitelline circulation. Given the similarities in the pathology of the abnormal vitelline circulation in many of these conditions, we hypothesized that the hyperglycemic insult present in diabetes could cause the resultant abnormalities in the vitelline circulation by affecting VEGF/VEGF receptor signaling pathway(s). In this study we report that hyperglycemic insult results in reduced levels of VEGF-A in the conceptus, which in turn, leads to abnormal VEGF receptor signaling, ultimately resulting in embryonic (vitelline) vasculopathy. These findings and our observation that addition of exogenous rVEGF-A(165) within a defined concentration range blunts the hyperglycemia-induced vasculopathy in the conceptus support the concept that VEGF levels can be modulated by glucose levels. In addition, these findings may ultimately lead to novel therapeutic approaches for the treatment of selected congenital cardiovascular abnormalities associated with diabetes.
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Affiliation(s)
- E Pinter
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520, USA
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276
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Abstract
Morphogenesis and developmental remodeling of cardiovascular tissues involve coordinated regulation of cell proliferation and apoptosis. In the heart, clear evidence points toward focal apoptosis as a contributor to development of the embryonic outflow tract, cardiac valves, conducting system, and the developing coronary vasculature. Apoptosis in the heart is likely regulated by survival and death signals that are also present in many other tissues. Cell type-specific regulation may be superimposed on general cell death/survival machinery through tissue-specific transcriptional pathways. In the vasculature, apoptosis almost certainly contributes to developmental vessel regression, and it is of proven importance in remodeling of arterial structure in response to local changes in hemodynamics. Physical forces, growth factors, and extracellular matrix drive vascular cell survival pathways, and considerable evidence points to local nitric oxide production as an important but complex regulator of vascular cell death. In both the heart and vasculature, progress has been impeded by inadequate information concerning the incidence of apoptosis, its relative importance compared with the diverse cell behaviors that remodel developing tissues, and by our primitive knowledge concerning regulation of cell death in these tissues. However, tools are now available to better understand apoptosis in normal and abnormal development of cardiovascular structures, and a framework has been established that should lead to considerable progress in the coming years.
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Affiliation(s)
- S A Fisher
- Departments of Medicine and Physiology, Case Western Reserve School of Medicine, Cleveland, Ohio, USA
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277
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Yancopoulos GD, Davis S, Gale NW, Rudge JS, Wiegand SJ, Holash J. Vascular-specific growth factors and blood vessel formation. Nature 2000; 407:242-8. [PMID: 11001067 DOI: 10.1038/35025215] [Citation(s) in RCA: 2648] [Impact Index Per Article: 110.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A recent explosion in newly discovered vascular growth factors has coincided with exploitation of powerful new genetic approaches for studying vascular development. An emerging rule is that all of these factors must be used in perfect harmony to form functional vessels. These new findings also demand re-evaluation of therapeutic efforts aimed at regulating blood vessel growth in ischaemia, cancer and other pathological settings.
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Affiliation(s)
- G D Yancopoulos
- Regeneron Pharmacueticals, Inc., Tarrytown, New York 10591, USA
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