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Klaus A, Birchmeier W. Developmental signaling in myocardial progenitor cells: a comprehensive view of Bmp- and Wnt/beta-catenin signaling. Pediatr Cardiol 2009; 30:609-16. [PMID: 19099173 DOI: 10.1007/s00246-008-9352-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 11/15/2008] [Indexed: 12/22/2022]
Abstract
The tight regulation of different signaling systems and the transcriptional and translational networks during embryonic development have been the focus of embryologists in recent decades. Defective developmental signaling due to genetic mutation or temporal and region-specific alteration of gene expression causes embryonic lethality or accounts for birth defects (e.g., congenital heart disease). The formation of the heart requires the coordinated integration of multiple cardiac progenitor cell populations derived from the first and second heart fields and from cardiac neural crest cells. This article summarizes what has been learned from conditional mutagenesis of Bmp pathway components and the Wnt effector, beta-catenin, in the developing heart of mice. Although Bmp signaling is required for cardiac progenitor cell specification, proliferation, and differentiation, recent studies have demonstrated distinct functions of Wnt/beta-catenin signaling at various stages of heart development.
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Affiliation(s)
- Alexandra Klaus
- Max-Delbrueck-Center for Molecular Medicine, Robert-Roessle-Strasse 10, 13125 Berlin, Germany
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52
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Speck NA, Iruela-Arispe ML. Conditional Cre/LoxP strategies for the study of hematopoietic stem cell formation. Blood Cells Mol Dis 2009; 43:6-11. [PMID: 19250847 PMCID: PMC2723839 DOI: 10.1016/j.bcmd.2009.01.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 01/05/2009] [Indexed: 11/30/2022]
Abstract
Some of the questions that have intrigued developmental biologists studying blood cell formation are: where do blood cells form, what are their precursors, and what signals are required for their emergence. Elegant embryonic grafting experiments in non-mammalian vertebrates, transplantation assays in mouse, and genetic analyses in zebrafish and mouse have been brought to bear on these problems, with enormous success. More recently investigators have applied conditional gene deletion and replacement strategies to refine our knowledge of this process in mammals. Here we describe several studies that have used the Cre/LoxP system to study blood cell formation, and what has been learned as a result.
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Affiliation(s)
- Nancy A Speck
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
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53
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David L, Feige JJ, Bailly S. Emerging role of bone morphogenetic proteins in angiogenesis. Cytokine Growth Factor Rev 2009; 20:203-12. [PMID: 19502096 DOI: 10.1016/j.cytogfr.2009.05.001] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bone morphogenetic proteins (BMPs) are multifunctional growth factors belonging to the transforming growth factor beta (TGFbeta) superfamily. Recent observations clearly emphasize the emerging role of BMPs in angiogenesis: (i) two genetic vascular diseases (hereditary hemorrhagic telangiectasia (HHT) and pulmonary arterial hypertension (PAH)) are caused by mutations in genes encoding components of the BMP signalling pathway (endoglin, ALK1 and BMPRII). (ii) BMP9 has been identified as the physiological ligand of the endothelial receptor ALK1 in association with BMPRII. This review will focus on the diverse functions of BMPs in angiogenesis. We will propose a model that distinguishes the BMP2, BMP7 and GDF5 subgroups from the BMP9 subgroup on the basis of their functional implication in the two phases of angiogenesis (activation and maturation).
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Affiliation(s)
- Laurent David
- Institut National de la Santé et de la Recherche Médicale, U878, 17 rue des Martyrs, 38054 Grenoble, France
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54
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Huang Z, Wang D, Ihida-Stansbury K, Jones PL, Martin JF. Defective pulmonary vascular remodeling in Smad8 mutant mice. Hum Mol Genet 2009; 18:2791-801. [PMID: 19419974 DOI: 10.1093/hmg/ddp214] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Pulmonary artery hypertension (PAH), a progressive, lethal condition that results in pathologic changes in the pulmonary arterial tree, eventually leads to right heart failure. Work identifying mutations in the Type II Bone morphogenetic protein (Bmp) receptor, BmpRII, in families with PAH has implicated Bmp-signaling in the pathogenesis of PAH. However, the effectors downstream of BmpRII in PAH remain unclear since BmpRII signals via Smad-dependent and independent mechanisms. We investigated Smad8 function, a divergent receptor regulated Smad downstream of Bmp-signaling, using gene targeting in mice. We show that Smad8 loss of function in adults resulted in characteristic changes in distal pulmonary arteries including medial thickening and smooth muscle hyperplasia that is observed in patients with PAH. Smad8 mutant pulmonary vasculature had upregulated Activin/Tgfbeta signaling and pathologic remodeling with aberrant Prx1 and Tenascin-C expression. A subset of Smad8 mutants had pulmonary adenomas uncovering a function for Smad8 in normal growth control. These findings implicate Smad8 in both pulmonary hypertension and lung tumorigenesis and support Smad8 as a candidate gene for PAH in humans.
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Affiliation(s)
- Zheng Huang
- Institute of Biosciences and Technology, Texas A&M System Health Science Center, 2121 W. Holcombe Blvd, Houston, TX 77030, USA
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55
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Danesh SM, Villasenor A, Chong D, Soukup C, Cleaver O. BMP and BMP receptor expression during murine organogenesis. Gene Expr Patterns 2009; 9:255-65. [PMID: 19393343 DOI: 10.1016/j.gep.2009.04.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 04/04/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
Abstract
Cell-cell communication is critical for regulating embryonic organ growth and differentiation. The Bone Morphogenetic Protein (BMP) family of transforming growth factor beta (TGFbeta) molecules represents one class of such cell-cell signaling molecules that regulate the morphogenesis of several organs. Due to high redundancy between the myriad BMP ligands and receptors in certain tissues, it has been challenging to address the role of BMP signaling using targeting of single Bmp genes in mouse models. Here, we present a detailed study of the developmental expression profiles of three BMP ligands (Bmp2, Bmp4, Bmp7) and three BMP receptors (Bmpr1a, Bmpr1b, and BmprII), as well as their molecular antagonist (noggin), in the early embryo during the initial steps of murine organogenesis. In particular, we focus on the expression of Bmp family members in the first organs and tissues that take shape during embryogenesis, such as the heart, vascular system, lungs, liver, stomach, nervous system, somites and limbs. Using in situ hybridization, we identify domains where ligand(s) and receptor(s) are either singly or co-expressed in specific tissues. In addition, we identify a previously unnoticed asymmetric expression of Bmp4 in the gut mesogastrium, which initiates just prior to gut turning and the establishment of organ asymmetry in the gastrointestinal tract. Our studies will aid in the future design and/or interpretation of targeted deletion of individual Bmp or Bmpr genes, since this study identifies organs and tissues where redundant BMP signaling pathways are likely to occur.
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Affiliation(s)
- Shahab M Danesh
- Department of Molecular Biology, NA8.300, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148, USA
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56
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Murakami M, Simons M. Regulation of vascular integrity. J Mol Med (Berl) 2009; 87:571-82. [PMID: 19337719 DOI: 10.1007/s00109-009-0463-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 03/03/2009] [Accepted: 03/06/2009] [Indexed: 12/13/2022]
Abstract
The integrity of blood vessels is critical to vascular homeostasis. Maintenance of vascular integrity has been conventionally regarded as a passive process that is largely dependent on continuous blood flow. Recent studies, however, have begun unveiling molecular processes essential for maintenance of vascular integrity and homeostasis under physiological conditions, leading to the notion that maintenance of the vasculature is an active biological process that requires continuous, basal cellular signaling. Failure of this system results in serious consequences such as hemorrhage, edema, inflammation, and tissue ischemia. In this review, we will discuss the emerging concepts in regulation of vascular integrity with the emphasis on structural components of blood vessels that are essential for vascular maintenance.
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Affiliation(s)
- Masahiro Murakami
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
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Xu K, Chong DC, Rankin SA, Zorn AM, Cleaver O. Rasip1 is required for endothelial cell motility, angiogenesis and vessel formation. Dev Biol 2009; 329:269-79. [PMID: 19272373 DOI: 10.1016/j.ydbio.2009.02.033] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 02/20/2009] [Accepted: 02/24/2009] [Indexed: 01/27/2023]
Abstract
Ras proteins are small GTPases that regulate cellular growth and differentiation. Components of the Ras signaling pathway have been shown to be important during embryonic vasculogenesis and angiogenesis. Here, we report that Rasip1, which encodes a novel Ras-interacting protein, is strongly expressed in vascular endothelial cells throughout development, in both mouse and frog. Similar to the well-characterized vascular markers VEGFR2 and PECAM, Rasip1 is specifically expressed in angioblasts prior to vessel formation, in the initial embryonic vascular plexus, in the growing blood vessels during angiogenesis and in the endothelium of mature blood vessels into the postnatal period. Rasip1 expression is undetectable in VEGFR2 null embryos, which lack endothelial cells, suggesting that Rasip1 is endothelial specific. siRNA-mediated reduction of Rasip1 severely impairs angiogenesis and motility in endothelial cell cultures, and morpholino knockdown experiments in frog embryos demonstrate that Rasip1 is required for embryonic vessel formation in vivo. Together, these data identify Rasip1 as a novel endothelial factor that plays an essential role in vascular development.
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Affiliation(s)
- Ke Xu
- Department of Molecular Biology, NA8.300, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148, USA
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58
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Nostro MC, Cheng X, Keller GM, Gadue P. Wnt, activin, and BMP signaling regulate distinct stages in the developmental pathway from embryonic stem cells to blood. Cell Stem Cell 2009; 2:60-71. [PMID: 18371422 DOI: 10.1016/j.stem.2007.10.011] [Citation(s) in RCA: 235] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 09/07/2007] [Accepted: 10/24/2007] [Indexed: 11/25/2022]
Abstract
The embryonic stem cell differentiation system was used to define the roles of the Activin/Nodal, BMP, and canonical Wnt signaling pathways at three distinct developmental stages during hematopoietic ontogeny: induction of a primitive streak-like population, formation of Flk1(+) mesoderm, and induction of hematopoietic progenitors. Activin/Nodal and Wnt, but not BMP, signaling are required for the induction of the primitive streak. Although BMP is not required for primitive streak induction, it displays a strong posteriorizing effect on this population. All three signaling pathways regulate induction of Flk1(+) mesoderm. The specification of Flk1(+) mesoderm to the hematopoietic lineages requires VEGF and Wnt, but not BMP or Activin/Nodal signaling. Specifically, Wnt signaling is essential for commitment of the primitive erythroid, but not the definitive lineages. These findings highlight dynamic changes in signaling requirements during blood cell development and identify a role for Wnt signaling in the establishment of the primitive erythroid lineage.
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Affiliation(s)
- M Cristina Nostro
- McEwen Centre for Regenerative Medicine, University Health Network, Toronto, ON M5G 1L7, Canada
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59
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Lengerke C, Schmitt S, Bowman TV, Jang IH, Maouche-Chretien L, McKinney-Freeman S, Davidson AJ, Hammerschmidt M, Rentzsch F, Green JBA, Zon LI, Daley GQ. BMP and Wnt specify hematopoietic fate by activation of the Cdx-Hox pathway. Cell Stem Cell 2009; 2:72-82. [PMID: 18371423 DOI: 10.1016/j.stem.2007.10.022] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 10/11/2007] [Accepted: 10/31/2007] [Indexed: 01/10/2023]
Abstract
The formation of blood in the embryo is dependent on bone morphogenetic protein (BMP), but how BMP signaling intersects with other regulators of hematopoietic development is unclear. Using embryonic stem (ES) cells, we show that BMP4 first induces ventral-posterior (V-P) mesoderm and subsequently directs mesodermal cells toward blood fate by activating Wnt3a and upregulating Cdx and Hox genes. When BMP signaling is blocked during this latter phase, enforced expression of either Cdx1 or Cdx4 rescues hematopoietic development, thereby placing BMP4 signaling upstream of the Cdx-Hox pathway. Wnt signaling cooperates in BMP-induced hemogenesis, and the Wnt effector LEF1 mediates BMP4 activation of Cdx genes. Our data suggest that BMP signaling plays two distinct and sequential roles during blood formation, initially as an inducer of mesoderm, and later to specify blood via activation of Wnt signaling and the Cdx-Hox pathway.
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Affiliation(s)
- Claudia Lengerke
- Division of Pediatric Hematology/Oncology, Children's Hospital Boston and Dana Farber Cancer Institute, Boston, MA 02115, USA
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60
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Goldman DC, Donley N, Christian JL. Genetic interaction between Bmp2 and Bmp4 reveals shared functions during multiple aspects of mouse organogenesis. Mech Dev 2008; 126:117-27. [PMID: 19116164 DOI: 10.1016/j.mod.2008.11.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 11/15/2008] [Accepted: 11/30/2008] [Indexed: 11/25/2022]
Abstract
Vertebrate Bmp2 and Bmp4 diverged from a common ancestral gene and encode closely related proteins. Mice homozygous for null mutations in either gene show early embryonic lethality, thereby precluding analysis of shared functions. In the current studies, we present phenotypic analysis of compound mutant mice heterozygous for a null allele of Bmp2 in combination with null or hypomorphic alleles of Bmp4. Whereas mice lacking a single copy of Bmp2 or Bmp4 are viable and have subtle developmental defects, compound mutants show embryonic and postnatal lethality due to defects in multiple organ systems including the allantois, placental vasculature, ventral body wall, skeleton, eye and heart. Within the heart, BMP2 and BMP4 function coordinately to direct normal lengthening of the outflow tract, proper positioning of the outflow vessels, and septation of the atria, ventricle and atrioventricular canal. Our results identify numerous BMP4-dependent developmental processes that are also very sensitive to BMP2 dosage, thus revealing novel functions of Bmp2.
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Affiliation(s)
- Devorah C Goldman
- Department of Cell and Developmental Biology, Oregon Health and Sciences University, School of Medicine, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, USA
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61
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Blank U, Seto ML, Adams DC, Wojchowski DM, Karolak MJ, Oxburgh L. An in vivo reporter of BMP signaling in organogenesis reveals targets in the developing kidney. BMC DEVELOPMENTAL BIOLOGY 2008; 8:86. [PMID: 18801194 PMCID: PMC2561030 DOI: 10.1186/1471-213x-8-86] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 09/18/2008] [Indexed: 12/22/2022]
Abstract
Background Bone morphogenetic proteins (BMPs) regulate essential processes during organogenesis, and a functional understanding of these secreted proteins depends on identification of their target cells. In this study, we generate a transgenic reporter for organogenesis studies that we use to define BMP pathway activation in the developing kidney. Results Mouse strains reporting on BMP pathway activation were generated by transgenically expressing β-galactosidase under the control of BMP responsive elements from Id1. Reporter expression corresponds well with immunoassays for pathway activation in all organs studied, validating the model. Using these reporters we have generated a detailed map of cellular targets of BMP signaling in the developing kidney. We find that SMAD dependent BMP signaling is active in collecting duct trunks, but not tips. Furthermore, glomerular endothelial cells, and proximal nephron tubules from the renal vesicle stage onward show pathway activation. Surprisingly, little activation is detected in the nephrogenic zone of the kidney, and in organ culture BMP treatment fails to activate SMAD dependent BMP signaling in nephron progenitor cells. In contrast, signaling is efficiently induced in collecting duct tips. Conclusion Transgenic reporters driven by control elements from BMP responsive genes such as Id1 offer significant advantages in sensitivity and consistency over immunostaining for studies of BMP pathway activation. They also provide opportunities for analysis of BMP signaling in organ and primary cell cultures subjected to experimental manipulation. Using such a reporter, we made the surprising finding that SMAD dependent BMP signaling is inactive in nephron progenitors, and that these cells are refractory to activation by applied growth factors. Furthermore, we find that the BMP pathway is not normally active in collecting duct tips, but that it can be ectopically activated by BMP treatment, offering a possible explanation for the inhibitory effects of BMP treatment on collecting duct growth and branching.
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Affiliation(s)
- Ulrika Blank
- Department of Molecular Medicine, Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME 04074, USA.
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62
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Sridurongrit S, Larsson J, Schwartz R, Ruiz-Lozano P, Kaartinen V. Signaling via the Tgf-beta type I receptor Alk5 in heart development. Dev Biol 2008; 322:208-18. [PMID: 18718461 DOI: 10.1016/j.ydbio.2008.07.038] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 07/22/2008] [Accepted: 07/31/2008] [Indexed: 10/21/2022]
Abstract
Trophic factors secreted both from the endocardium and epicardium regulate appropriate growth of the myocardium during cardiac development. Epicardially-derived cells play also a key role in development of the coronary vasculature. This process involves transformation of epithelial (epicardial) cells to mesenchymal cells (EMT). Similarly, a subset of endocardial cells undergoes EMT to form the mesenchyme of endocardial cushions, which function as primordia for developing valves and septa. While it has been suggested that transforming growth factor-betas (Tgf-beta) play an important role in induction of EMT in the avian epi- and endocardium, the function of Tgf-betas in corresponding mammalian tissues is still poorly understood. In this study, we have ablated the Tgf-beta type I receptor Alk5 in endo-, myo- and epicardial lineages using the Tie2-Cre, Nkx2.5-Cre, and Gata5-Cre driver lines, respectively. We show that while Alk5-mediated signaling does not play a major role in the myocardium during mouse cardiac development, it is critically important in the endocardium for induction of EMT both in vitro and in vivo. Moreover, loss of epicardial Alk5-mediated signaling leads to disruption of cell-cell interactions between the epicardium and myocardium resulting in a thinned myocardium. Furthermore, epicardial cells lacking Alk5 fail to undergo Tgf-beta-induced EMT in vitro. Late term mutant embryos lacking epicardial Alk5 display defective formation of a smooth muscle cell layer around coronary arteries, and aberrant formation of capillary vessels in the myocardium suggesting that Alk5 is controlling vascular homeostasis during cardiogenesis. To conclude, Tgf-beta signaling via Alk5 is not required in myocardial cells during mammalian cardiac development, but plays an irreplaceable cell-autonomous role regulating cellular communication, differentiation and proliferation in endocardial and epicardial cells.
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Affiliation(s)
- Somyoth Sridurongrit
- University of Michigan, Department of Biologic and Materials Sciences, Ann Arbor, MI 48109, USA
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63
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El-Bizri N, Guignabert C, Wang L, Cheng A, Stankunas K, Chang CP, Mishina Y, Rabinovitch M. SM22alpha-targeted deletion of bone morphogenetic protein receptor 1A in mice impairs cardiac and vascular development, and influences organogenesis. Development 2008; 135:2981-91. [PMID: 18667463 DOI: 10.1242/dev.017863] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Expression of bone morphogenetic protein receptor 1A (BMPR1A) is attenuated in the lung vessels of patients with pulmonary arterial hypertension, but the functional impact of this abnormality is unknown. We ablated Bmpr1a in cardiomyocytes and vascular smooth muscle cells (VSMCs) by breeding mice possessing a loxP allele of Bmpr1a (Bmpr1aflox) expressing R26R with SM22alpha-Cre mice. SM22alpha-Cre;R26R;Bmpr1aflox/flox mice died soon after embryonic day 11 (E11) with massive vascular and pericardial hemorrhage and impaired brain development. At E10.5, SM22alpha-Cre;R26R;Bmpr1aflox/flox embryos showed thinning of the myocardium associated with reduced cell proliferation. These embryos also had severe dilatation of the aorta and large vessels with impaired investment of SMCs that was also related to reduced proliferation. SM22alpha-Cre;R26R;Bmpr1aflox/flox mice showed collapsed telencephalon in association with impaired clearing of brain microvessels in areas where reduced apoptosis was observed. Transcript and protein levels of matrix metalloproteinase (MMP) 2 and 9 were reduced in E9.5 and E10.5 SM22alpha-Cre;R26R;Bmpr1aflox/flox embryos, respectively. Knock-down of BMPR1A by RNA interference in human pulmonary artery SMCs reduced MMP2 and MMP9 activity, attenuated serum-induced proliferation, and impaired PDGF-BB-directed migration. RNA interference of MMP2 or MMP9 recapitulated these abnormalities, supporting a functional interaction between BMP signaling and MMP expression. In human brain microvascular pericytes, knock-down of BMPR1A reduced MMP2 activity and knock-down of either BMPR1A or MMP2 caused resistance to apoptosis. Thus, loss of Bmpr1a, by decreasing MMP2 and/or MMP9 activity, can account for vascular dilatation and persistence of brain microvessels, leading to the impaired organogenesis documented in the brain.
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Affiliation(s)
- Nesrine El-Bizri
- Cardiopulmonary Research Program, Vera Moulton Wall Center for Pulmonary Vascular Disease, Stanford University School of Medicine, Stanford, California, CA, USA
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Hong KH, Lee YJ, Lee E, Park SO, Han C, Beppu H, Li E, Raizada MK, Bloch KD, Oh SP. Genetic ablation of the BMPR2 gene in pulmonary endothelium is sufficient to predispose to pulmonary arterial hypertension. Circulation 2008; 118:722-30. [PMID: 18663089 DOI: 10.1161/circulationaha.107.736801] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Pulmonary arterial hypertension (PAH) is a rare but fatal lung disease of diverse origins. PAH is now further subclassified as idiopathic PAH, familial PAH, and associated PAH varieties. Heterozygous mutations in BMPR2 can be detected in 50% to 70% of patients with familial PAH and 10% to 40% of patients with idiopathic PAH. Although endothelial cells have been suspected as the cellular origin of PAH pathogenesis, no direct in vivo evidence has been clearly presented. The present study was designed to investigate whether endothelial Bmpr2 deletion can predispose to PAH. METHODS AND RESULTS The Bmpr2 gene was deleted in pulmonary endothelial cells using Bmpr2 conditional knockout mice and a novel endothelial Cre transgenic mouse line. Wide ranges of right ventricular systolic pressure were observed in mice with heterozygous (21.7 to 44.1 mm Hg; median, 23.7 mm Hg) and homozygous (20.7 to 56.3 mm Hg; median, 27 mm Hg) conditional deletion of Bmpr2 in pulmonary endothelial cells compared with control mice (19.9 to 26.7 mm Hg; median, 23 mm Hg) at 2 to 7 months of age. A subset of mice with right ventricular systolic pressure >30 mm Hg exhibited right ventricular hypertrophy and an increase in the number and wall thickness of muscularized distal pulmonary arteries. In the lungs of these mice with high right ventricular systolic pressure, the expression of proteins involved in the pathogenesis of PAH such as serotonin transporter and tenascin-C was elevated in distal arteries and had a high incidence of perivascular leukocyte infiltration and in situ thrombosis. CONCLUSIONS Conditional heterozygous or homozygous Bmpr2 deletion in pulmonary endothelial cells predisposes mice to develop PAH.
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Affiliation(s)
- Kwon-Ho Hong
- Department of Physiology and Functional Genomics, Shands Cancer Center, University of Florida College of Medicine, Gainesville, USA
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65
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Kaneko K, Li X, Zhang X, Lamberti JJ, Jamieson SW, Thistlethwaite PA. Endothelial expression of bone morphogenetic protein receptor type 1a is required for atrioventricular valve formation. Ann Thorac Surg 2008; 85:2090-8. [PMID: 18498827 DOI: 10.1016/j.athoracsur.2008.02.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/29/2008] [Accepted: 02/01/2008] [Indexed: 10/22/2022]
Abstract
BACKGROUND Atrioventricular canal defects account for 4% of all congenital heart anomalies. They arise from failure of endocardial cushion formation, a process dependent on transition of endothelial cells into clustered mesenchymal cells in the mid-atrioventricular septum. To date, the genetic signals necessary for atrioventricular canal defects are poorly understood. We hypothesized that bone morphogenetic protein signaling in cardiac endothelial cells may be crucial to this process. METHODS To study the role of bone morphogenetic protein receptors (Bmpr) in the developing heart, we created knockout mice with inactivation of Bmpr1a selectively in endocardium. Two strains of null mice were created: one with constitutive endothelial-specific knockout of Bmpr1a and one with time-inducible, endothelial-specific knockout of Bmpr1a. Embryos and animals were analyzed by microscopy, RNA in situ hybridization, and microangiography. RESULTS Animals with null mutation of Bmpr1a in endothelium were embryonic lethal at E11.5 to 12.0 and demonstrated absence of endocardial cushion formation. Embryos failed to form atrioventricular valves and adjacent septa. Endocardial knockout of Bmpr1a did not affect development of the outflow tract or aortic arches. Using time-inducible, cell-specific knockout mice, we show that Bmpr1a has two functions in the developing atrioventricular canal: to induce endocardial endothelial-mesenchymal transition, and to pattern the septal mesenchyme into endocardial cushions. We demonstrate that these processes are temporally linked to expression of the transcription factors Id1 and Id3. CONCLUSIONS Endocardial cushion formation is dependent on cell-specific expression of Bmpr1a. Our results suggest that Bmpr1a-mediated signaling is a crucial pathway involved in pathogenesis of atrioventricular septal and valve malformations, which are among the most common congenital heart defects in humans.
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Affiliation(s)
- Kan Kaneko
- Division of Cardiothoracic Surgery, University of California San Diego, San Diego, California 92103-8892, USA
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66
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Imura T, Tane K, Toyoda N, Fushiki S. Endothelial cell-derived bone morphogenetic proteins regulate glial differentiation of cortical progenitors. Eur J Neurosci 2008; 27:1596-606. [PMID: 18380662 DOI: 10.1111/j.1460-9568.2008.06134.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gliogenesis is an important component of cortical development during the postnatal period. Two macroglial cells are generated in a particular order, i.e. astrocytes first and oligodendrocytes later. The mechanisms underlying this sequence of glial differentiation are unknown but interactions with blood vessels are postulated to play a role. We show, using a mouse in-vitro coculture system, that endothelial cells promote astrocyte differentiation but inhibit oligodendrocyte differentiation of postnatal cortical progenitors. Endothelial cells produce bone morphogenetic proteins (BMPs) to activate Sma- and Mad-related protein (Smad) signalling in progenitors and the effects of endothelial cells on glial differentiation are blocked by the BMP antagonist Noggin. Differentiation of progenitors into astrocytes results in the inhibition of endothelial cell growth, accompanied by changes in gene expression of angiogenic factors, indicating bidirectional interactions between progenitors and endothelial cells. In vivo, Smad signalling is activated in various types of cortical cells including progenitors in association with astrogenesis but is inactivated before the peak of oligodendrogenesis. Capillary vessels isolated from the developing cortex express high levels of BMPs. Together, these results demonstrate that endothelial cells regulate glial differentiation by secreting BMPs in vitro and suggest a similar role in cortical gliogenesis in vivo.
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Affiliation(s)
- Tetsuya Imura
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
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Lee D, Park C, Lee H, Lugus JJ, Kim SH, Arentson E, Chung YS, Gomez G, Kyba M, Lin S, Janknecht R, Lim DS, Choi K. ER71 acts downstream of BMP, Notch, and Wnt signaling in blood and vessel progenitor specification. Cell Stem Cell 2008; 2:497-507. [PMID: 18462699 PMCID: PMC2683414 DOI: 10.1016/j.stem.2008.03.008] [Citation(s) in RCA: 252] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 01/23/2008] [Accepted: 03/12/2008] [Indexed: 11/28/2022]
Abstract
FLK1-expressing (FLK1(+)) mesoderm generates blood and vessels. Here, we show that combined BMP, Notch, and Wnt signaling is necessary for efficient FLK1(+) mesoderm formation from embryonic stem cells (ESCs). Inhibition of BMP, Notch, and Wnt signaling pathways greatly decreased the generation of FLK1(+) mesoderm and expression of the Ets transcription factor Er71. Enforced expression of ER71 in ESCs resulted in a robust induction of FLK1(+) mesoderm; rescued the generation of FLK1(+) mesoderm when blocked by BMP, Notch, and Wnt inhibition; and enhanced hematopoietic and endothelial cell generation. Er71-deficient mice had greatly reduced FLK1 expression, died early in gestation, and displayed severe blood and vessel defects that are highly reminiscent of the Flk1 null mouse phenotype. Collectively, we provide compelling evidence that ER71 functions downstream of BMP, Notch, and Wnt signals and regulates FLK1(+) mesoderm, blood, and vessel development.
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Affiliation(s)
- Dongjun Lee
- National Research Laboratory, Department of Biological Science, KAIST, Daejeon
| | - Changwon Park
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Ho Lee
- National Research Laboratory, Department of Biological Science, KAIST, Daejeon
- National Cancer Center, Goyangsi, Gyeonggi-do, Korea
| | - Jesse J. Lugus
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
- Molecular Cell Biology Program, Washington University School of Medicine, St. Louis, MO
| | - Seok Hyung Kim
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Elizabeth Arentson
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Yun Shin Chung
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Gustavo Gomez
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA
| | - Michael Kyba
- Department of Developmental Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Shuo Lin
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA
| | - Ralf Janknecht
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Dae-Sik Lim
- National Research Laboratory, Department of Biological Science, KAIST, Daejeon
| | - Kyunghee Choi
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
- Molecular Cell Biology Program, Washington University School of Medicine, St. Louis, MO
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68
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Dudas M, Wysocki A, Gelpi B, Tuan TL. Memory encoded throughout our bodies: molecular and cellular basis of tissue regeneration. Pediatr Res 2008; 63:502-12. [PMID: 18427295 DOI: 10.1203/pdr.0b013e31816a7453] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
When a sheep loses its tail, it cannot regenerate it in the manner of lizards. On the other hand, it is possible to clone mammals from somatic cells, showing that a complete developmental program is intact in a wounded sheep's tail the same way it is in a lizard. Thus, there is a requirement for more than only the presence of the entire genetic code in somatic cells for regenerative abilities. Thoughts like this have motivated us to assemble more than just a factographic synopsis on tissue regeneration. As a model, we review skin wound healing in chronological order, and when possible, we use that overview as a framework to point out possible mechanisms of how damaged tissues can restore their original structure. This article postulates the existence of tissue structural memory as a complex distributed homeostatic mechanism. We support such an idea by referring to an extremely fragmented literature base, trying to synthesize a broad picture of important principles of how tissues and organs may store information about their own structure for the purposes of regeneration. Selected developmental, surgical, and tissue engineering aspects are presented and discussed in the light of recent findings in the field. When a sheep loses its tail, it cannot regenerate it in the manner of lizards. On the other hand, it is possible to clone mammals from somatic cells, showing that a complete developmental program is intact in a wounded sheep's tail the same way it is in a lizard. Thus, there is a requirement for more than only the presence of the entire genetic code in somatic cells for regenerative abilities. Thoughts like this have motivated us to assemble more than just a factographic synopsis on tissue regeneration. As a model, we review skin wound healing in chronological order, and when possible, we use that overview as a framework to point out possible mechanisms of how damaged tissues can restore their original structure. This article postulates the existence of tissue structural memory as a complex distributed homeostatic mechanism. We support such an idea by referring to an extremely fragmented literature base, trying to synthesize a broad picture of important principles of how tissues and organs may store information about their own structure for the purposes of regeneration. Selected developmental, surgical, and tissue engineering aspects are presented and discussed in the light of recent findings in the field.
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Affiliation(s)
- Marek Dudas
- Developmental Biology Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
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69
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Baldessari D, Mione M. How to create the vascular tree? (Latest) help from the zebrafish. Pharmacol Ther 2008; 118:206-30. [PMID: 18439684 DOI: 10.1016/j.pharmthera.2008.02.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 02/19/2008] [Indexed: 12/22/2022]
Abstract
The cardiovascular system provides oxygen, nutrients and hormones to organs, it directs traffic of metabolites and it maintains tissue homeostasis. It is one of the first organs assembled during vertebrate development and it is essential to life from early stages to adult. For these reasons, the process of vessel formation has being studied for more than a century, but it is only in the late eighties that there has been an explosion of research in the field with the employment of various in vitro and in vivo model systems. The zebrafish (Danio rerio) offers several advantages for in vivo studies; it played a fundamental role in new discoveries and helped to refine our knowledge of the vascular system. This review recapitulates the zebrafish data on vasculogenesis and angiogenesis, including the specification of the haemangioblasts from the mesoderm, their migration to form the vascular cord followed by axial vessels specification, the primary and secondary sprouting of intersomitic vessels, the formation of the lumen, the arterial versus venous specification and patterning. To emphasize the strengths of the zebrafish system in the vascular field, we summarize main tools, such as gene expression and mutagenesis screens, knock down technologies, transgenic lines and imaging, which played a major role in the development of the field and allowed significant discoveries, for instance the recent visualization of the lymphatic system in zebrafish. This information contributes to the prospective of drug discovery to cure human diseases linked to angiogenesis, not last tumours.
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Affiliation(s)
- Danila Baldessari
- IFOM-IEO Campus (FIRC Institute of Molecular Oncology Foundation-European Institute of Oncology), Via Adamello 16, 20139 Milan, Italy.
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70
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Endoglin-Mediated Vascular Remodeling: Mechanisms Underlying Hereditary Hemorrhagic Telangiectasia. Trends Cardiovasc Med 2008; 18:25-32. [DOI: 10.1016/j.tcm.2007.11.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 11/08/2007] [Accepted: 11/13/2007] [Indexed: 11/18/2022]
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71
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Abstract
Congenital heart defects occur in nearly 1% of human live births and many are lethal if not surgically repaired. In addition, the genetic contribution to congenital or acquired cardiovascular diseases that are silent at birth, but progress to cause significant disease in later life is being increasingly appreciated. Heart development and structure are highly conserved between mouse and human. The discoveries that are being made in this model system are highly relevant to understanding the pathogenesis of human heart defects whether they occus in isolation, or in the context of a syndrome. Many of the genes required for cardiovascular development were discovered fortuitously when early lethality or structural defects were observed in mouse mutants generated for other purposes, and relevant genes continue to be defined in this manner. Candidate genes for this process are being identified by their roles other species, or by their expression in pertinent tissues in mice. In this review, I will briefly summarize heart development as currently understood in the mouse, and then discuss how complementary studies in mouse and human have identified genes and pathways that are critical for normal cardiovascular development, and for maintaining the structure and function of this organ system throughout life.
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Affiliation(s)
- Anne Moon
- School of Medicine, University of Utah, Salt Lake City, UT 84112, USA
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72
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Inai K, Norris RA, Hoffman S, Markwald RR, Sugi Y. BMP-2 induces cell migration and periostin expression during atrioventricular valvulogenesis. Dev Biol 2007; 315:383-96. [PMID: 18261719 DOI: 10.1016/j.ydbio.2007.12.028] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 12/19/2007] [Accepted: 12/20/2007] [Indexed: 11/26/2022]
Abstract
Atrioventricular (AV) endocardium transforms into the cushion mesenchyme, the primordia of the valves and membranous septa, through epithelial-mesenchymal transformation (EMT). While bone morphogenetic protein (BMP)-2 is known to be critical for AV EMT, the role of BMP-2 in post-EMT AV valvulogenesis remains to be elucidated. To find BMP signaling loops, we first localized Type I BMP receptors (BMPRs), BMPR-1A (ALK3), -1B (ALK6) and ALK2 in AV cushion mesenchyme in stage-24 chick embryos. Based on the BMP receptor expression pattern, we examined the functional roles of BMP-2 and BMP signaling in post-EMT valvulogenesis by using stage-24 AV cushion mesenchymal cell aggregates cultured on 3D-collagen gels. Exogenous BMP-2 or constitutively active (ca) BMPR-1B (ALK6)-virus treatments induced migration of the mesenchymal cells into the collagen gels, whereas noggin, an antagonist of BMPs, or dominant-negative (dn) BMPR-1 B (ALK6)-virus treatments reduced cell migration from the mesenchymal cell aggregates. Exogenous BMP-2 or caBMPR-1B (ALK6) treatments significantly promoted expression of an extracellular matrix (ECM) protein, periostin, a known valvulogenic matrix maturation mediator, at both mRNA and protein levels, whereas periostin expression was repressed by adding noggin or dnBMPR-1B (ALK6)-virus to the culture. Moreover, transcripts of Twist and Id1, which have been implicated in cell migration in embryogenesis and activation of the periostin promoter, were induced by BMP-2 but repressed by noggin in cushion mesenchymal cell cultures. These data provide evidence that BMP-2 and BMP signaling induce biological processes involved in early AV valvulogenesis, i.e. mesenchymal cell migration and expression of periostin, indicating critical roles for BMP signaling in post-EMT AV cushion tissue maturation and differentiation.
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Affiliation(s)
- Kei Inai
- Department of Cell Biology and Anatomy and Cardiovascular Developmental Biology Center, Medical University of South Carolina, 171 Ashley Ave., Charleston, SC 29425, USA
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73
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Bibliography. Current world literature. Parathyroids, bone and mineral metabolism. Curr Opin Endocrinol Diabetes Obes 2007; 14:494-501. [PMID: 17982358 DOI: 10.1097/med.0b013e3282f315ef] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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74
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Schiedlmeier B, Santos AC, Ribeiro A, Moncaut N, Lesinski D, Auer H, Kornacker K, Ostertag W, Baum C, Mallo M, Klump H. HOXB4's road map to stem cell expansion. Proc Natl Acad Sci U S A 2007; 104:16952-7. [PMID: 17940039 PMCID: PMC2040480 DOI: 10.1073/pnas.0703082104] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Indexed: 01/22/2023] Open
Abstract
Homeodomain-containing transcription factors are important regulators of stem cell behavior. HOXB4 mediates expansion of adult and embryo-derived hematopoietic stem cells (HSCs) when expressed ectopically. To define the underlying molecular mechanisms, we performed gene expression profiling in combination with subsequent functional analysis with enriched adult HSCs and embryonic derivatives expressing inducible HOXB4. Thereby, we identified a set of overlapping genes that likely represent "universal" targets of HOXB4. A substantial number of loci are involved in signaling pathways important for controlling self-renewal, maintenance, and differentiation of stem cells. Functional assays performed on selected pathways confirmed the biological coherence of the array results. HOXB4 activity protected adult HSCs from the detrimental effects mediated by the proinflammatory cytokine TNF-alpha. This protection likely contributes to the competitive repopulation advantage of HOXB4-expressing HSCs observed in vivo. The concept of TNF-alpha inhibition may also prove beneficial for patients undergoing bone marrow transplantation. Furthermore, we demonstrate that HOXB4 activity and FGF signaling are intertwined. HOXB4-mediated expansion of adult and ES cell-derived HSCs was enhanced by specific and complete inhibition of FGF receptors. In contrast, the expanding activity of HOXB4 on hematopoietic progenitors in day 4-6 embryoid bodies was blunted in the presence of basic FGF (FGF2), indicating a dominant negative effect of FGF signaling on the earliest hematopoietic cells. In summary, our results strongly suggest that HOXB4 modulates the response of HSCs to multiple extrinsic signals in a concerted manner, thereby shifting the balance toward stem cell self-renewal.
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Affiliation(s)
- Bernhard Schiedlmeier
- *Department of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Strasse1, 30625 Hannover, Germany
| | | | - Ana Ribeiro
- Instituto Gulbenkian de Ciencia, 2780-156 Oeiras, Portugal
| | | | - Dietrich Lesinski
- *Department of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Strasse1, 30625 Hannover, Germany
| | - Herbert Auer
- Columbus Children's Research Institute, Columbus, OH 43210; and
| | - Karl Kornacker
- Division of Sensory Biophysics, Ohio State University, Columbus, OH 43205
| | - Wolfram Ostertag
- *Department of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Strasse1, 30625 Hannover, Germany
| | - Christopher Baum
- *Department of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Strasse1, 30625 Hannover, Germany
| | - Moises Mallo
- Instituto Gulbenkian de Ciencia, 2780-156 Oeiras, Portugal
| | - Hannes Klump
- *Department of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Strasse1, 30625 Hannover, Germany
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75
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Park SO, Lee YJ, Seki T, Hong KH, Fliess N, Jiang Z, Park A, Wu X, Kaartinen V, Roman BL, Oh SP. ALK5- and TGFBR2-independent role of ALK1 in the pathogenesis of hereditary hemorrhagic telangiectasia type 2. Blood 2007; 111:633-42. [PMID: 17911384 PMCID: PMC2200847 DOI: 10.1182/blood-2007-08-107359] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
ALK1 belongs to the type I receptor family for transforming growth factor-beta family ligands. Heterozygous ALK1 mutations cause hereditary hemorrhagic telangiectasia type 2 (HHT2), a multisystemic vascular disorder. Based largely on in vitro studies, TGF-beta1 has been considered as the most likely ALK1 ligand related to HHT, yet the identity of the physiologic ALK1 ligand remains controversial. In cultured endothelial cells, ALK1 and another TGF-beta type I receptor, ALK5, regulate angiogenesis by controlling TGF-beta signal transduction, and ALK5 is required for ALK1 signaling. However, the extent to which such interactions between these 2 receptors play a role in pathogenesis of HHT is unknown. We directly addressed these issues in vivo by comparing the phenotypes of mice in which the Alk1, Alk5, or Tgfbr2 gene was conditionally deleted in restricted vascular endothelia using a novel endothelial Cre transgenic line. Alk1-conditional deletion resulted in severe vascular malformations mimicking all pathologic features of HHT. Yet Alk5- or Tgfbr2-conditional deletion in mice, or Alk5 inhibition in zebrafish, did not affect vessel morphogenesis. These data indicate that neither ALK5 nor TGFBR2 is required for ALK1 signaling pertinent to the pathogenesis of HHT and suggest that HHT might not be a TGF-beta subfamily disease.
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MESH Headings
- Activin Receptors, Type I/genetics
- Activin Receptors, Type I/metabolism
- Activin Receptors, Type II
- Animals
- Cell Line
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Ligands
- Mice
- Mice, Knockout
- Neovascularization, Pathologic/genetics
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Receptor, Transforming Growth Factor-beta Type I
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Transforming Growth Factor beta/genetics
- Receptors, Transforming Growth Factor beta/metabolism
- Signal Transduction/genetics
- Telangiectasia, Hereditary Hemorrhagic/genetics
- Telangiectasia, Hereditary Hemorrhagic/metabolism
- Telangiectasia, Hereditary Hemorrhagic/pathology
- Transforming Growth Factor beta1/genetics
- Transforming Growth Factor beta1/metabolism
- Zebrafish/genetics
- Zebrafish/metabolism
- Zebrafish Proteins
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Affiliation(s)
- Sung O Park
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Shands Cancer Center, Gainesville 32610, USA
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76
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Liu D, Wang J, Kinzel B, Müeller M, Mao X, Valdez R, Liu Y, Li E. Dosage-dependent requirement of BMP type II receptor for maintenance of vascular integrity. Blood 2007; 110:1502-10. [PMID: 17496203 DOI: 10.1182/blood-2006-11-058594] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
AbstractGerm-line mutations in bone morphogenic protein type II receptor (Bmpr2) confer susceptibility to pulmonary arterial hypertension (PAH), which is characterized by obstructive vascular lesions in small arteries. The molecular and cellular mechanisms that account for the etiology of this disorder remain elusive, as does the role of Bmpr2 in postnatal tissue homeostasis. Here we show that in adult mice, stably silencing Bmpr2 expression by RNA interference does not increase pulmonary arterial resistance but results in severe mucosal hemorrhage, incomplete mural cell coverage on vessel walls, and gastrointestinal hyperplasia. We present evidence that BMP receptor signaling regulates vascular remodeling during angiogenesis by maintaining the expression of endothelial guidance molecules that promote vessel patterning and maturation and by counteracting growth factor–induced AKT activation. Attenuation of this function may cause vascular dysmorphogenesis and predisposition to angioproliferative diseases. Our findings provide a mechanistic link between PAH and other diseases associated with the BMP/TGF-β pathways, such as hereditary hemorrhagic telangiectasia and juvenile polyposis syndrome.
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MESH Headings
- Adenomatous Polyposis Coli/genetics
- Adenomatous Polyposis Coli/metabolism
- Adenomatous Polyposis Coli/pathology
- Animals
- Bone Morphogenetic Protein Receptors, Type II/genetics
- Bone Morphogenetic Protein Receptors, Type II/metabolism
- Gene Dosage
- Germ-Line Mutation
- Hemorrhage/genetics
- Hemorrhage/metabolism
- Homeostasis/genetics
- Hypertension, Pulmonary/genetics
- Hypertension, Pulmonary/metabolism
- Hypertension, Pulmonary/pathology
- Mice
- Mice, Knockout
- Neovascularization, Pathologic/genetics
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Proto-Oncogene Proteins c-akt/metabolism
- RNA Interference
- Telangiectasia, Hereditary Hemorrhagic/genetics
- Telangiectasia, Hereditary Hemorrhagic/metabolism
- Telangiectasia, Hereditary Hemorrhagic/pathology
- Transforming Growth Factor beta/genetics
- Transforming Growth Factor beta/metabolism
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Affiliation(s)
- Dong Liu
- Developmental and Molecular Pathways, Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA.
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77
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Lan Y, Liu B, Yao H, Li F, Weng T, Yang G, Li W, Cheng X, Mao N, Yang X. Essential role of endothelial Smad4 in vascular remodeling and integrity. Mol Cell Biol 2007; 27:7683-92. [PMID: 17724086 PMCID: PMC2169040 DOI: 10.1128/mcb.00577-07] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
New blood vessels are formed through the assembly or sprouting of endothelial cells (ECs) and become stabilized by the formation of perivascular matrix and the association with supporting mural cells. To investigate the role of endothelial Smad4 in vascular development, we deleted the Smad4 gene specifically in ECs using the Cre-LoxP system. EC-specific Smad4 mutant mice died at embryonic day 10.5 due to cardiovascular defects, including attenuated vessels sprouting and remodeling, collapsed dorsal aortas, enlarged hearts with reduced trabeculae, and failed endocardial cushion formation. Noticeably, Smad4-deficient ECs demonstrated an intrinsic defect in tube formation in vitro. Furthermore, the mutant vascular ECs dissociated away from the surrounding cells and suffered from impaired development of vascular smooth muscle cells. The disturbed vascular integrity and maturation was associated with aberrant expression of angiopoietins and a gap junction component, connexin43. Collectively, we have provided direct functional evidence that Smad4 activity in the developing ECs is essential for blood vessel remodeling, maturation, and integrity.
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Affiliation(s)
- Yu Lan
- Genetic Laboratory of Development and Diseases, Institute of Biotechnology, 20 Dongdajie, Beijing 100071, People's Republic of China
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78
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Takashima S, Shimada A, Kobayashi D, Yokoi H, Narita T, Jindo T, Kage T, Kitagawa T, Kimura T, Sekimizu K, Miyake A, Setiamarga DHE, Murakami R, Tsuda S, Ooki S, Kakihara K, Hojo M, Naruse K, Mitani H, Shima A, Ishikawa Y, Araki K, Saga Y, Takeda H. Phenotypic analysis of a novelchordinmutant in medaka. Dev Dyn 2007; 236:2298-310. [PMID: 17654721 DOI: 10.1002/dvdy.21245] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have isolated and characterized a ventralized mutant in medaka (the Japanese killifish; Oryzias latipes), which turned out to have a mutation in the chordin gene. The mutant exhibits ventralization of the body axis, malformation of axial bones, over-bifurcation of yolk sac blood vessels, and laterality defects in internal organs. The mutant exhibits variability of phenotypes, depending on the culture temperature, from embryos with a slightly ventralized phenotype to those without any head and trunk structures. Taking advantages of these variable and severe phenotypes, we analyzed the role of Chordin-dependent tissues such as the notochord and Kupffer's vesicle (KV) in the establishment of left-right axis in fish. The results demonstrate that, in the absence of the notochord and KV, the medaka lateral plate mesoderm autonomously and bilaterally expresses spaw gene in a default state.
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Affiliation(s)
- Shigeo Takashima
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
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79
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Umans L, Cox L, Tjwa M, Bito V, Vermeire L, Laperre K, Sipido K, Moons L, Huylebroeck D, Zwijsen A. Inactivation of Smad5 in endothelial cells and smooth muscle cells demonstrates that Smad5 is required for cardiac homeostasis. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:1460-72. [PMID: 17456754 PMCID: PMC1854943 DOI: 10.2353/ajpath.2007.060839] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Smads are intracellular signaling proteins that transduce signals elicited by members of the transforming growth factor (TGF)-beta superfamily. Smad5 and Smad1 are highly homologous, and they mediate primarily bone morphogenetic protein (Bmp) signals. We used the Cre-loxP system and Sm22-Cre and Tie-1-Cre mice to study the function of Smad5 in the developing blood vessel wall. Analysis of embryos demonstrated that deletion of Smad5 in endothelial or smooth muscle cells resulted in a normal organization of embryonic and extra-embryonic vasculature. Angiogenic assays performed in adult mice revealed that mutant mice display a comparable angiogenic and vascular remodeling response to control mice. In Sm22-Cre; Smad5(fl/-) mice, Smad5 is also deleted in cardiomyocytes. Echocardiographic analysis on those 9-month-old female mice demonstrated larger left ventricle internal diameters and decreased fractional shortening compared with control littermates without signs of cardiac hypertrophy. The decreased cardiac contractility was associated with a decreased performance in a treadmill experiment. In isolated cardiomyocytes, fractional shortening was significantly reduced compared with control cells. These data demonstrate that restricted deletion of Smad5 in the blood vessel wall results in viable mice. However, loss of Smad5 in cardiomyocytes leads to a mild heart defect.
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Affiliation(s)
- Lieve Umans
- Department for Molecular and Developmental Genetics, VIB, Leuven, Belgium
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80
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Narumiya H, Hidaka K, Shirai M, Terami H, Aburatani H, Morisaki T. Endocardiogenesis in embryoid bodies: Novel markers identified by gene expression profiling. Biochem Biophys Res Commun 2007; 357:896-902. [PMID: 17462595 DOI: 10.1016/j.bbrc.2007.04.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 04/05/2007] [Indexed: 11/27/2022]
Abstract
Endocardial cells and cardiomyocytes differentiate from the cardiogenic mesoderm at about the same time during development. Although in vitro embryonic stem (ES) cell systems have been used to study the differentiation of various types of cell lineages, including cardiomyocytes, smooth muscle cells, and vascular endothelial cells, differentiation of endocardial cells, or endocardiogenesis, has not been well reported, because of a lack of specific molecular markers. In our search for cardiogenesis-associated genes expressed in embryoid bodies, we found several genes expressed in the heart region of mouse embryos, but not in cardiomyocytes. To identify the cell types expressing these genes, CD31(+) cells were taken from mouse embryos on embryonic day (E)8.5 and E9.5 and sorted, then their transcripts were analyzed using quantitative RT-PCR analyses. In those embryos, Gata4 and Nfatc1, as well as newly identified Cgnl1 and Dok4 were found to be preferentially expressed in endocardial cells, but not in yolk sac endothelial cells, while Cdh5 and Kdr were expressed in both cardiac and yolk sac endothelial cells. Immunohistochemical analyses of embryoid bodies revealed that some CD31(+) cells co-expressing Gata4 and Nfatc1 were located in close proximity to cardiomyocytes. These results suggest that embryoid bodies express endocardial specific genes and likely generate endocardial cells along with cardiomyocytes. Further, they indicate that these new marker genes are useful to study the origin and induction of endocardial cells, and identify other endocardial markers.
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Affiliation(s)
- Hiromichi Narumiya
- Department of Bioscience, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
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Jin SW, Herzog W, Santoro MM, Mitchell TS, Frantsve J, Jungblut B, Beis D, Scott IC, D'Amico LA, Ober EA, Verkade H, Field HA, Chi NC, Wehman AM, Baier H, Stainier DYR. A transgene-assisted genetic screen identifies essential regulators of vascular development in vertebrate embryos. Dev Biol 2007; 307:29-42. [PMID: 17531218 PMCID: PMC2695512 DOI: 10.1016/j.ydbio.2007.03.526] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 03/30/2007] [Accepted: 03/30/2007] [Indexed: 11/18/2022]
Abstract
Formation of a functional vasculature during mammalian development is essential for embryonic survival. In addition, imbalance in blood vessel growth contributes to the pathogenesis of numerous disorders. Most of our understanding of vascular development and blood vessel growth comes from investigating the Vegf signaling pathway as well as the recent observation that molecules involved in axon guidance also regulate vascular patterning. In order to take an unbiased, yet focused, approach to identify novel genes regulating vascular development, we performed a three-step ENU mutagenesis screen in zebrafish. We first screened live embryos visually, evaluating blood flow in the main trunk vessels, which form by vasculogenesis, and the intersomitic vessels, which form by angiogenesis. Embryos that displayed reduced or absent circulation were fixed and stained for endogenous alkaline phosphatase activity to reveal blood vessel morphology. All putative mutants were then crossed into the Tg(flk1:EGFP)(s843) transgenic background to facilitate detailed examination of endothelial cells in live and fixed embryos. We screened 4015 genomes and identified 30 mutations affecting various aspects of vascular development. Specifically, we identified 3 genes (or loci) that regulate the specification and/or differentiation of endothelial cells, 8 genes that regulate vascular tube and lumen formation, 8 genes that regulate vascular patterning, and 11 genes that regulate vascular remodeling, integrity and maintenance. Only 4 of these genes had previously been associated with vascular development in zebrafish illustrating the value of this focused screen. The analysis of the newly defined loci should lead to a greater understanding of vascular development and possibly provide new drug targets to treat the numerous pathologies associated with dysregulated blood vessel growth.
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Affiliation(s)
- Suk-Won Jin
- Department of Biochemistry and Biophysics, Genetics and Human Genetics, and Cardiovascular Research Institute, University of California San Francisco, CA 94158, USA.
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Functional BMP receptor in endocardial cells is required in atrioventricular cushion mesenchymal cell formation in chick. Dev Biol 2007; 306:179-92. [PMID: 17449024 DOI: 10.1016/j.ydbio.2007.03.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 03/09/2007] [Accepted: 03/09/2007] [Indexed: 11/25/2022]
Abstract
Transformation of atrioventricular (AV) canal endocardium into invasive mesenchyme correlates spatially and temporally with the expression of bone morphogenetic protein (BMP)-2 in the AV myocardium. We revealed the presence of mRNA of Type I BMP receptors, BMPR-1A (ALK3), BMPR-1B (ALK6) and ALK2 in chick AV endocardium at stage-14(-), the onset of epithelial to mesenchymal transformation (EMT), by RT-PCR and localized BMPR-1B mRNA in the endocardium by in situ hybridization. To circumvent the functional redundancies among the Type I BMP receptors, we applied dominant-negative (dn) BMPR-1B-viruses to chick AV explants and whole-chick embryo cultures to specifically block BMP signaling in AV endocardium during EMT. dnBMPR-1B-virus infection of AV endocardial cells abolished BMP-2-supported AV endocardial EMT. Conversely, caBMPR-1B-virus infection promoted AV endocardial EMT in the absence of AV myocardium. Moreover, dnBMPR-1B-virus treatments significantly reduced myocardially supported EMT in AV endocardial-myocardial co-culture. AV cushion mesenchymal cell markers, alpha-smooth muscle actin (SMA), and TGFbeta3 in the endocardial cells were promoted by caBMPR-1B and reduced by dnBMPR-1B infection. Microinjection of the virus into the cardiac jelly in the AV canal at stage-13 in vivo (ovo) revealed that the dnBMPR-1B-virus-infected cells remained in the endocardial epithelium, whereas caBMPR-1B-infected cells invaded deep into the cushions. These results provide evidence that BMP signaling through the AV endocardium is required for the EMT and the activation of the BMP receptor in the endocardium can promote AV EMT in the chick.
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