RESUMEN
A central function of the vascular endothelium is to serve as a barrier between the blood and the surrounding tissue of the body. At the same time, solutes and cells have to pass the endothelium to leave or to enter the bloodstream to maintain homeostasis. Under pathological conditions, for example, inflammation, permeability for fluid and cells is largely increased in the affected area, thereby facilitating host defense. To appropriately function as a regulated permeability filter, the endothelium uses various mechanisms to allow solutes and cells to pass the endothelial layer. These include transcellular and paracellular pathways of which the latter requires remodeling of intercellular junctions for its regulation. This review provides an overview on endothelial barrier regulation and focuses on the endothelial signaling mechanisms controlling the opening and closing of paracellular pathways for solutes and cells such as leukocytes and metastasizing tumor cells.
Asunto(s)
Células Endoteliales/fisiología , Endotelio Vascular/fisiología , Transducción de Señal/fisiología , Animales , Barrera Alveolocapilar/fisiología , Barrera Hematoencefálica/fisiología , Endotelio Vascular/citología , HumanosRESUMEN
The extravasation of leukocytes is a critical step during inflammation that requires the localized opening of the endothelial barrier. This process is initiated by the close interaction of leukocytes with various adhesion molecules such as ICAM-1 on the surface of endothelial cells. Here we reveal that mechanical forces generated by leukocyte-induced clustering of ICAM-1 synergize with fluid shear stress exerted by the flowing blood to increase endothelial plasma membrane tension and to activate the mechanosensitive cation channel PIEZO1. This leads to increases in [Ca2+]i and activation of downstream signaling events including phosphorylation of tyrosine kinases sarcoma (SRC) and protein tyrosine kinase 2 (PYK2), as well as of myosin light chain, resulting in opening of the endothelial barrier. Mice with endothelium-specific Piezo1 deficiency show decreased leukocyte extravasation in different inflammation models. Thus, leukocytes and the hemodynamic microenvironment synergize to mechanically activate endothelial PIEZO1 and subsequent downstream signaling to initiate leukocyte diapedesis.
Asunto(s)
Canales Iónicos , Leucocitos , Migración Transendotelial y Transepitelial , Animales , Células Endoteliales/metabolismo , Endotelio Vascular/metabolismo , Inflamación/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Canales Iónicos/genética , Canales Iónicos/metabolismo , Leucocitos/metabolismo , RatonesRESUMEN
G protein-coupled receptor 182 (GPR182) has been shown to be expressed in endothelial cells; however, its ligand and physiological role has remained elusive. We found GPR182 to be expressed in microvascular and lymphatic endothelial cells of most organs and to bind with nanomolar affinity the chemokines CXCL10, CXCL12, and CXCL13. In contrast to conventional chemokine receptors, binding of chemokines to GPR182 did not induce typical downstream signaling processes, including Gq- and Gi-mediated signaling or ß-arrestin recruitment. GPR182 showed relatively high constitutive activity in regard to ß-arrestin recruitment and rapidly internalized in a ligand-independent manner. In constitutive GPR182-deficient mice, as well as after induced endothelium-specific loss of GPR182, we found significant increases in the plasma levels of CXCL10, CXCL12, and CXCL13. Global and induced endothelium-specific GPR182-deficient mice showed a significant decrease in hematopoietic stem cells in the bone marrow as well as increased colony-forming units of hematopoietic progenitors in the blood and the spleen. Our data show that GPR182 is a new atypical chemokine receptor for CXCL10, CXCL12, and CXCL13, which is involved in the regulation of hematopoietic stem cell homeostasis.
Asunto(s)
Receptores Acoplados a Proteínas G/metabolismo , Animales , Quimiocina CXCL10 , Quimiocina CXCL12 , Quimiocina CXCL13 , Quimiocinas/metabolismo , Células Endoteliales/metabolismo , Femenino , Células HEK293 , Células Madre Hematopoyéticas/metabolismo , Homeostasis , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Receptores de Quimiocina/metabolismo , Receptores Acoplados a Proteínas G/genética , Transducción de Señal/fisiología , beta-Arrestinas/metabolismoRESUMEN
Metastasis is the leading cause of cancer-related death in humans. It is a complex multistep process during which individual tumour cells spread primarily through the circulatory system to colonize distant organs. Once in the circulation, tumour cells remain vulnerable, and their metastatic potential largely depends on a rapid and efficient way to escape from the blood stream by passing the endothelial barrier. Evidence has been provided that tumour cell extravasation resembles leukocyte transendothelial migration. However, it remains unclear how tumour cells interact with endothelial cells during extravasation and how these processes are regulated on a molecular level. Here we show that human and murine tumour cells induce programmed necrosis (necroptosis) of endothelial cells, which promotes tumour cell extravasation and metastasis. Treatment of mice with the receptor-interacting serine/threonine-protein kinase 1 (RIPK1)-inhibitor necrostatin-1 or endothelial-cell-specific deletion of RIPK3 reduced tumour-cell-induced endothelial necroptosis, tumour cell extravasation and metastasis. In contrast, pharmacological caspase inhibition or endothelial-cell-specific loss of caspase-8 promoted these processes. We furthermore show in vitro and in vivo that tumour-cell-induced endothelial necroptosis leading to extravasation and metastasis requires amyloid precursor protein expressed by tumour cells and its receptor, death receptor 6 (DR6), on endothelial cells as the primary mediators of these effects. Our data identify a new mechanism underlying tumour cell extravasation and metastasis, and suggest endothelial DR6-mediated necroptotic signalling pathways as targets for anti-metastatic therapies.
Asunto(s)
Apoptosis , Células Endoteliales/metabolismo , Células Endoteliales/patología , Necrosis , Metástasis de la Neoplasia , Neoplasias/patología , Receptores del Factor de Necrosis Tumoral/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Apoptosis/efectos de los fármacos , Caspasa 8/genética , Inhibidores de Caspasas/farmacología , Línea Celular , Modelos Animales de Enfermedad , Femenino , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Células Endoteliales de la Vena Umbilical Humana/patología , Humanos , Imidazoles/farmacología , Indoles/farmacología , Masculino , Ratones , Necrosis/tratamiento farmacológico , Metástasis de la Neoplasia/tratamiento farmacológico , Neoplasias/metabolismo , Proteína Serina-Treonina Quinasas de Interacción con Receptores/antagonistas & inhibidores , Proteína Serina-Treonina Quinasas de Interacción con Receptores/deficiencia , Migración Transendotelial y Transepitelial/efectos de los fármacosRESUMEN
In the mammalian embryo, few mechanical signals have been identified to influence organ development and function. Here, we report that an increase in the volume of interstitial or extracellular fluid mechanically induces growth of an organ system, that is, the lymphatic vasculature. We first demonstrate that lymph vessel expansion in the developing mouse embryo correlates with a peak in interstitial fluid pressure and lymphatic endothelial cell (LEC) elongation. In 'loss-of-fluid' experiments, we then show that aspiration of interstitial fluid reduces the length of LECs, decreases tyrosine phosphorylation of vascular endothelial growth factor receptor-3 (VEGFR3), and inhibits LEC proliferation. Conversely, in 'gain-of-fluid' experiments, increasing the amount of interstitial fluid elongates the LECs, and increases both VEGFR3 phosphorylation and LEC proliferation. Finally, we provide genetic evidence that ß1 integrins are required for the proliferative response of LECs to both fluid accumulation and cell stretching and, therefore, are necessary for lymphatic vessel expansion and fluid drainage. Thus, we propose a new and physiologically relevant mode of VEGFR3 activation, which is based on mechanotransduction and is essential for normal development and fluid homeostasis in a mammalian embryo.
Asunto(s)
Vasos Linfáticos/citología , Mecanotransducción Celular , Animales , Proliferación Celular , Humanos , Integrina beta1/genética , Integrina beta1/fisiología , Ratones , Fosforilación , Transducción de Señal , Receptor 3 de Factores de Crecimiento Endotelial Vascular/metabolismoRESUMEN
OBJECTIVE: Transforming growth factor-ß-activated kinase 1 (TAK1) is a mitogen-activated protein 3-kinase and an AMP-activated protein kinase (AMPK) kinase in some cell types. Although TAK1(-/-) mice display defects in developmental vasculogenesis, the role of TAK1 in endothelial cells has not been investigated in detail. APPROACH AND RESULTS: TAK1 downregulation (small interfering RNA) in human endothelial cells attenuated proliferation without inducing apoptosis and diminished endothelial cell migration, as well as tube formation. Cytokine- and vascular endothelial growth factor (VEGF)-induced endothelial cell sprouting in a modified spheroid assay were abrogated by TAK1 downregulation. Moreover, VEGF-induced endothelial sprouting was impaired in aortic rings from mice lacking TAK1 in endothelial cells (TAK(ΔEC)). TAK1 inhibition and downregulation also inhibited VEGF-stimulated phosphorylation of several kinases, including AMPK. Proteomic analyses revealed that superoxide dismutase 2 (SOD2) expression was reduced in TAK1-deficient endothelial cells, resulting in attenuated hydrogen peroxide production but increased mitochondrial superoxide production. Endothelial cell SOD2 expression was also attenuated by AMPK inhibition and in endothelial cells from AMPKα1(-/-) mice but was unaffected by inhibitors of c-Jun N-terminal kinase, p38, extracellular signal-regulated kinase 1/2, or phosphatidylinositol 3-kinase/Akt. Moreover, the impaired endothelial sprouting from TAK(ΔEC) aortic rings was abrogated in the presence of polyethylene glycol-SOD, and tube formation was normalized by the overexpression of SOD2. A similar rescue of angiogenesis was observed in polyethylene glycol-SOD-treated aortic rings from mice with endothelial cell-specific deletion of the AMPKα1. CONCLUSIONS: These results establish TAK1 as an AMPKα1 kinase that regulates vascular endothelial growth factor-induced and cytokine-induced angiogenesis by modulating SOD2 expression and the superoxide anion:hydrogen peroxide balance.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Células Endoteliales/enzimología , Quinasas Quinasa Quinasa PAM/metabolismo , Proteínas Quinasas Activadas por AMP/antagonistas & inhibidores , Proteínas Quinasas Activadas por AMP/deficiencia , Proteínas Quinasas Activadas por AMP/genética , Animales , Antioxidantes/farmacología , Movimiento Celular , Proliferación Celular , Células Cultivadas , Células Endoteliales/efectos de los fármacos , Células Endoteliales de la Vena Umbilical Humana/enzimología , Humanos , Peróxido de Hidrógeno/metabolismo , Interleucina-1beta/metabolismo , Quinasas Quinasa Quinasa PAM/antagonistas & inhibidores , Quinasas Quinasa Quinasa PAM/deficiencia , Quinasas Quinasa Quinasa PAM/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mitocondrias/metabolismo , Neovascularización Fisiológica , Oxidación-Reducción , Fosforilación , Inhibidores de Proteínas Quinasas/farmacología , Interferencia de ARN , Receptores de LDL/genética , Receptores de LDL/metabolismo , Transducción de Señal , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1 , Factores de Tiempo , Transfección , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
Within the tumor microenvironment, tumor cells and endothelial cells regulate each other. While tumor cells induce angiogenic responses in endothelial cells, endothelial cells release angiocrine factors, which act on tumor cells and other stromal cells. We report that tumor cell-derived adrenomedullin has a pro-angiogenic as well as a direct tumor-promoting effect, and that endothelium-derived CC chemokine ligand 2 (CCL2) suppresses adrenomedullin-induced tumor cell proliferation. Loss of the endothelial adrenomedullin receptor CALCRL or of the G-protein Gs reduced endothelial proliferation. Surprisingly, tumor cell proliferation was also reduced after endothelial deletion of CALCRL or Gs. We identified CCL2 as a critical angiocrine factor whose formation is inhibited by adrenomedullin. Furthermore, CCL2 inhibited adrenomedullin formation in tumor cells through its receptor CCR2. Consistently, loss of endothelial CCL2 or tumor cell CCR2 normalized the reduced tumor growth seen in mice lacking endothelial CALCRL or Gs. Our findings show tumor-promoting roles of adrenomedullin and identify CCL2 as an angiocrine factor controlling adrenomedullin formation by tumor cells.
Asunto(s)
Adrenomedulina , Quimiocina CCL2 , Neoplasias , Animales , Ratones , Adrenomedulina/farmacología , Proliferación Celular , Quimiocina CCL2/genética , Quimiocinas , Células Endoteliales/patología , Ligandos , Neoplasias/genética , Neoplasias/patología , Receptores CCR2/genética , Microambiente TumoralRESUMEN
Metastasis is the major cause of death in cancer patients. Circulating tumor cells need to migrate through the endothelial layer of blood vessels to escape the hostile circulation and establish metastases at distant organ sites. Here, we identified the membrane-bound metalloprotease ADAM17 on endothelial cells as a key driver of metastasis. We show that TNFR1-dependent tumor cell-induced endothelial cell death, tumor cell extravasation, and subsequent metastatic seeding is dependent on the activity of endothelial ADAM17. Moreover, we reveal that ADAM17-mediated TNFR1 ectodomain shedding and subsequent processing by the γ-secretase complex is required for the induction of TNF-induced necroptosis. Consequently, genetic ablation of ADAM17 in endothelial cells as well as short-term pharmacological inhibition of ADAM17 prevents long-term metastases formation in the lung. Thus, our data identified ADAM17 as a novel essential regulator of necroptosis and as a new promising target for antimetastatic and advanced-stage cancer therapies.
Asunto(s)
Proteína ADAM17/antagonistas & inhibidores , Células Endoteliales/metabolismo , Necroptosis , Neoplasias/etiología , Neoplasias/patología , Animales , Antineoplásicos/farmacología , Biomarcadores , Biomarcadores de Tumor , Comunicación Celular , Muerte Celular , Susceptibilidad a Enfermedades/inmunología , Humanos , Necroptosis/genética , Invasividad Neoplásica , Metástasis de la Neoplasia , Siembra Neoplásica , Neoplasias/metabolismo , Neoplasias/terapia , Proteolisis , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Microambiente Tumoral/efectos de los fármacos , Microambiente Tumoral/genética , Microambiente Tumoral/inmunología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
The cardiovascular system developed early in evolution and is pivotal for the transport of oxygen, nutrients, and waste products within the organism. It is composed of hollow tubular structures and has a high level of complexity in vertebrates. This complexity is, at least in part, due to the endothelial cell lining of vertebrate blood vessels. However, vascular lumen formation by endothelial cells is still controversially discussed. For example, it has been suggested that the lumen mainly forms via coalescence of large intracellular vacuoles generated by pinocytosis. Alternatively, it was proposed that the vascular lumen initiates extracellularly between adjacent apical endothelial cell surfaces. Here we discuss invertebrate and vertebrate cardiovascular lumen formation and highlight the possible modes of blood vessel formation. Finally, we point to the importance of a better understanding of vascular lumen formation for treating human pathologies, including cancer and coronary heart disease.
Asunto(s)
Sistema Cardiovascular/metabolismo , Invertebrados/metabolismo , Vertebrados/metabolismo , Animales , Vasos Sanguíneos/metabolismo , Células Endoteliales/metabolismo , Espacio Extracelular/metabolismo , Humanos , Morfogénesis , Neoplasias/metabolismo , Pinocitosis , Vacuolas/metabolismoRESUMEN
Damage-induced fibrotic scarring limits tissue regeneration in mammals and is a leading cause of morbidity. In contrast, species like zebrafish can regenerate damaged tissues without excessive fibrosis. However, whether specific signaling pathways can both limit fibrosis and promote regeneration is unclear. Here, we show that interleukin-11 (Il-11)/Stat3 signaling has such a dual function. Zebrafish lacking Il-11 receptor function display severely compromised heart, fin, and scale regeneration. Deep phenotyping and transcriptional analysis of adult hearts and fins show that Il-11 signaling drives cellular reprogramming to orchestrate global and tissue-specific regenerative programs and broadly antagonizes hallmarks of adult mammalian scarring. Mechanistically, our data indicate that IL-11 signaling in endothelial cells antagonizes profibrotic transforming growth factorß signaling and endothelial-to-mesenchymal transition, limiting scarring and promoting cardiomyocyte repopulation, after injury. Overall, our findings position damage-induced Il-11/Stat3 signaling in a key role limiting fibrosis and promoting regeneration, revealing novel targets for regenerative therapies.
RESUMEN
Somatic stem cells expand massively during tissue regeneration, which might require control of cell fitness, allowing elimination of non-competitive, potentially harmful cells. How or if such cells are removed to restore organ function is not fully understood. Here, we show that a substantial fraction of muscle stem cells (MuSCs) undergo necroptosis because of epigenetic rewiring during chronic skeletal muscle regeneration, which is required for efficient regeneration of dystrophic muscles. Inhibition of necroptosis strongly enhances suppression of MuSC expansion in a non-cell-autonomous manner. Prevention of necroptosis in MuSCs of healthy muscles is mediated by the chromatin remodeler CHD4, which directly represses the necroptotic effector Ripk3, while CHD4-dependent Ripk3 repression is dramatically attenuated in dystrophic muscles. Loss of Ripk3 repression by inactivation of Chd4 causes massive necroptosis of MuSCs, abolishing regeneration. Our study demonstrates how programmed cell death in MuSCs is tightly controlled to achieve optimal tissue regeneration.
Asunto(s)
Epigénesis Genética/genética , Músculo Esquelético/metabolismo , Necroptosis/genética , HumanosRESUMEN
Formation of metastases is the major cause of death in patients diagnosed with cancer. It is a complex multistep process, including tumor cell migration, intravasation, survival in the circulation, and extravasation. Previously it was shown that tumor cell-induced endothelial necroptosis promotes tumor cell extravasation and metastasis. Here, we identified endothelial TGF-ß-activated kinase 1 (TAK1) as a critical regulator of endothelial necroptosis and metastasis. Human and murine endothelial cells lacking TAK1 exhibit higher levels of necroptosis both in vitro and in vivo, and mice with endothelial cell-specific loss of TAK1 are more prone to form metastases. Endothelial RIPK3, a key component of the necroptotic machinery, was upregulated in mice with endothelial TAK1-deficiency, and endothelial knockout of RIPK3 reverted the effects of TAK1-deficiency. Moreover, altered expression levels of TAK1 and RIPK3 in pulmonary endothelial cells of mice bearing primary tumors correlated with increased endothelial necroptosis and metastasis. Together, our data suggest an important protective role for endothelial TAK1 in tumor progression by keeping endothelial necroptosis in check.
Asunto(s)
Células Endoteliales/enzimología , Quinasas Quinasa Quinasa PAM/metabolismo , Necroptosis/fisiología , Animales , Línea Celular Tumoral , Movimiento Celular/fisiología , Células Endoteliales/citología , Humanos , Melanoma Experimental/metabolismo , Melanoma Experimental/patología , Ratones , Metástasis de la Neoplasia , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Transducción de SeñalRESUMEN
During developmental angiogenesis, blood vessels grow and remodel to ultimately build a hierarchical vascular network. Whether, how, cell death signaling molecules contribute to blood vessel formation is still not well understood. Caspase-8 (Casp-8), a key protease in the extrinsic cell death-signaling pathway, regulates cell death via both apoptosis and necroptosis. Here, we show that expression of Casp-8 in endothelial cells (ECs) is required for proper postnatal retina angiogenesis. EC-specific Casp-8-KO pups (Casp-8ECKO) showed reduced retina angiogenesis, as the loss of Casp-8 reduced EC proliferation, sprouting, and migration independently of its cell death function. Instead, the loss of Casp-8 caused hyperactivation of p38 MAPK downstream of receptor-interacting serine/threonine protein kinase 3 (RIPK3) and destabilization of vascular endothelial cadherin (VE-cadherin) at EC junctions. In a mouse model of oxygen-induced retinopathy (OIR) resembling retinopathy of prematurity (ROP), loss of Casp-8 in ECs was beneficial, as pathological neovascularization was reduced in Casp-8ECKO pups. Taking these data together, we show that Casp-8 acts in a cell death-independent manner in ECs to regulate the formation of the retina vasculature and that Casp-8 in ECs is mechanistically involved in the pathophysiology of ROP.
Asunto(s)
Caspasa 8/metabolismo , Neovascularización Patológica , Neovascularización Fisiológica , Retina/embriología , Animales , Animales Recién Nacidos , Antígenos CD/metabolismo , Cadherinas/metabolismo , Muerte Celular , Movimiento Celular , Proliferación Celular , Células Endoteliales/metabolismo , Femenino , Células Endoteliales de la Vena Umbilical Humana , Humanos , Pulmón/embriología , Ratones , Ratones Noqueados , Necroptosis , Oxígeno/metabolismo , Fosforilación , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genética , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Transducción de Señal , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
The vascular endothelium is constantly exposed to mechanical forces, including fluid shear stress exerted by the flowing blood. Endothelial cells can sense different flow patterns and convert the mechanical signal of laminar flow into atheroprotective signals, including eNOS activation, whereas disturbed flow in atheroprone areas induces inflammatory signaling, including NF-κB activation. How endothelial cells distinguish different flow patterns is poorly understood. Here we show that both laminar and disturbed flow activate the same initial pathway involving the mechanosensitive cation channel Piezo1, the purinergic P2Y2 receptor, and Gq/G11-mediated signaling. However, only disturbed flow leads to Piezo1- and Gq/G11-mediated integrin activation resulting in focal adhesion kinase-dependent NF-κB activation. Mice with induced endothelium-specific deficiency of Piezo1 or Gαq/Gα11 show reduced integrin activation, inflammatory signaling, and progression of atherosclerosis in atheroprone areas. Our data identify critical steps in endothelial mechanotransduction, which distinguish flow pattern-dependent activation of atheroprotective and atherogenic endothelial signaling and suggest novel therapeutic strategies to treat inflammatory vascular disorders such as atherosclerosis.
Asunto(s)
Endotelio Vascular/inmunología , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/inmunología , Subunidades alfa de la Proteína de Unión al GTP/inmunología , Integrinas/inmunología , Canales Iónicos/inmunología , Animales , Aterosclerosis/genética , Aterosclerosis/inmunología , Aterosclerosis/patología , Endotelio Vascular/patología , Subunidades alfa de la Proteína de Unión al GTP/genética , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/genética , Humanos , Inflamación/genética , Inflamación/inmunología , Inflamación/patología , Integrinas/genética , Canales Iónicos/genética , Ratones , Óxido Nítrico Sintasa de Tipo III/genética , Óxido Nítrico Sintasa de Tipo III/inmunología , Transducción de Señal/genética , Transducción de Señal/inmunologíaRESUMEN
Formation of the lymphatic system requires the coordinated expression of several key regulators: vascular endothelial growth factor C (VEGFC), its receptor FLT4, and a key transcriptional effector, PROX1. Yet, how expression of these signaling components is regulated remains poorly understood. Here, using a combination of genetic and molecular approaches, we identify the transcription factor hematopoietically expressed homeobox (HHEX) as an upstream regulator of VEGFC, FLT4, and PROX1 during angiogenic sprouting and lymphatic formation in vertebrates. By analyzing zebrafish mutants, we found that hhex is necessary for sprouting angiogenesis from the posterior cardinal vein, a process required for lymphangiogenesis. Furthermore, studies of mammalian HHEX using tissue-specific genetic deletions in mouse and knockdowns in cultured human endothelial cells reveal its highly conserved function during vascular and lymphatic development. Our findings that HHEX is essential for the regulation of the VEGFC/FLT4/PROX1 axis provide insights into the molecular regulation of lymphangiogenesis.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Proteínas de Homeodominio/genética , Linfangiogénesis/genética , Proteínas Represoras/genética , Proteínas Supresoras de Tumor/genética , Factor C de Crecimiento Endotelial Vascular/genética , Receptor 3 de Factores de Crecimiento Endotelial Vascular/genética , Proteínas de Pez Cebra/genética , Animales , Animales Modificados Genéticamente , Secuencia de Bases , Vasos Sanguíneos/citología , Vasos Sanguíneos/crecimiento & desarrollo , Vasos Sanguíneos/metabolismo , Línea Celular , Embrión de Mamíferos , Embrión no Mamífero , Células Endoteliales/citología , Células Endoteliales/metabolismo , Proteínas de Homeodominio/metabolismo , Humanos , Vasos Linfáticos/citología , Vasos Linfáticos/metabolismo , Ratones , Neovascularización Fisiológica/genética , Proteínas Represoras/deficiencia , Transducción de Señal , Transcripción Genética , Proteínas Supresoras de Tumor/metabolismo , Factor C de Crecimiento Endotelial Vascular/metabolismo , Receptor 3 de Factores de Crecimiento Endotelial Vascular/metabolismo , Pez Cebra , Proteínas de Pez Cebra/deficiencia , Proteínas de Pez Cebra/metabolismoRESUMEN
Endothelial cells are equipped with the intrinsic ability to form tubes and sprouts with a central lumen. However, the mechanisms that allow endothelial cells to form a lumen are largely unknown. We would like to discuss critically current models of vascular lumen formation and point to many unexplored and open questions. We briefly present what vascular researchers can learn from the formation of other cell systems with a lumen, such as cysts formed by Madin-Darby Canine Kidney (MDCK) cells as well as tracheae formed by Drosophila epithelial cells. In addition, we point to a number of questions that need to be addressed to understand better the cell biology that drives the formation of a vascular lumen.
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Vasos Sanguíneos/embriología , Neovascularización Fisiológica , Animales , Vasos Sanguíneos/citología , Muerte Celular , Perros , Drosophila melanogaster , Células Endoteliales/citología , Espacio Extracelular/metabolismo , Modelos Biológicos , Fagocitosis , Tráquea/irrigación sanguínea , Tráquea/citología , Vacuolas/metabolismoRESUMEN
Most metastasizing tumor cells reach distant sites by entering the circulatory system. Within the bloodstream, they are exposed to severe stress due to loss of adhesion to extracellular matrix, hemodynamic shear forces, and attacks of the immune system, and only a few cells manage to extravasate and to form metastases. We review the current understanding of the cellular and molecular mechanisms that allow tumor cells to survive in the intravascular environment and that mediate and promote tumor cell extravasation. As these processes are critical for the metastatic spread of tumor cells, we discuss implications for potential therapeutic approaches and future research.
Asunto(s)
Extravasación de Materiales Terapéuticos y Diagnósticos/patología , Células Neoplásicas Circulantes/patología , Animales , Anoicis , Supervivencia Celular , Extravasación de Materiales Terapéuticos y Diagnósticos/terapia , Humanos , Sistema Inmunológico/patología , Estrés MecánicoRESUMEN
Elevated blood pressure is a key risk factor for developing cardiovascular diseases. Blood pressure is largely determined by vasodilatory mediators, such as nitric oxide (NO), that are released from the endothelium in response to fluid shear stress exerted by the flowing blood. Previous work has identified several mechanotransduction signaling processes that are involved in fluid shear stress-induced endothelial effects, but how fluid shear stress initiates the response is poorly understood. Here, we evaluated human and bovine endothelial cells and found that the purinergic receptor P2Y2 and the G proteins Gq/G11 mediate fluid shear stress-induced endothelial responses, including [Ca2+]i transients, activation of the endothelial NO synthase (eNOS), phosphorylation of PECAM-1 and VEGFR-2, as well as activation of SRC and AKT. In response to fluid shear stress, endothelial cells released ATP, which activates the purinergic P2Y2 receptor. Mice with induced endothelium-specific P2Y2 or Gq/G11 deficiency lacked flow-induced vasodilation and developed hypertension that was accompanied by reduced eNOS activation. Together, our data identify P2Y2 and Gq/G11 as a critical endothelial mechanosignaling pathway that is upstream of previously described mechanotransduction processes and demonstrate that P2Y2 and Gq/G11 are required for basal endothelial NO formation, vascular tone, and blood pressure.
Asunto(s)
Presión Sanguínea/fisiología , Señalización del Calcio/fisiología , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Mecanotransducción Celular/fisiología , Receptores Purinérgicos P2Y2/metabolismo , Animales , Bovinos , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/genética , Células Endoteliales de la Vena Umbilical Humana/citología , Humanos , Hipertensión/genética , Hipertensión/metabolismo , Hipertensión/patología , Ratones , Ratones Noqueados , Óxido Nítrico/genética , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo III/genética , Óxido Nítrico Sintasa de Tipo III/metabolismo , Receptores Purinérgicos P2Y2/genética , Receptor 2 de Factores de Crecimiento Endotelial Vascular/genética , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo , Vasodilatación/fisiologíaRESUMEN
Tumor cells can activate platelets, which in turn facilitate tumor cell survival and dissemination. The exact mechanisms by which platelets promote metastasis have remained unclear. Here, we show that adenine nucleotides released from tumor cell-activated platelets induce opening of the endothelial barrier to allow transendothelial migration of tumor cells and thereby promote cancer cell extravasation. We identified the endothelial P2Y2 receptor, which is activated by ATP, as the primary mediator of this effect. Mice deficient in P2Y2 or lacking ATP secretion from platelets show strongly reduced tumor cell metastasis. These findings demonstrate a mechanism by which platelets promote cancer cell metastasis and suggest the P2Y2 receptor and its endothelial downstream signaling mechanisms as a target for antimetastatic therapies.
Asunto(s)
Adenosina Trifosfato/fisiología , Plaquetas/fisiología , Movimiento Celular , Células Endoteliales/fisiología , Metástasis de la Neoplasia , Neoplasias/patología , Receptores Purinérgicos P2Y2/fisiología , Animales , Gránulos Citoplasmáticos/fisiología , Humanos , RatonesRESUMEN
Formation of new blood and lymphatic vessels is involved in many physiological and pathological processes, including organ and tumor growth, cancer cell metastasis, fluid drainage and lymphedema. Therefore, the ability to manipulate vascularization in a mammalian system is of particular interest to researchers. Here we describe a method for pharmacological manipulation of de novo and sprouting blood and lymphatic vascular development in ex vivo-cultured mouse embryos. The described protocol can also be used to evaluate the properties of pharmacological agents in growing mammalian tissues and to manipulate other developmental processes. The whole procedure, from embryo isolation to image quantification, takes 3-5 d, depending on the analysis and age of the embryos.