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The proliferation of the endothelium is a highly coordinated process to ensure the emergence, expansion, and homeostasis of the vasculature. While Bone Morphogenetic Protein (BMP) signaling fine-tunes the behaviors of endothelium in health and disease, how BMP signaling influences the proliferation of endothelium and therefore, modulates angiogenesis remains largely unknown. Here, we evaluated the role of Activin A Type I Receptor (ACVR1/ALK2), a key BMP receptor in the endothelium, in modulating the proliferation of endothelial cells. We show that ACVR1/ALK2 is a key modulator for the proliferation of endothelium in the retinal vessels. Loss of endothelial ALK2 leads to a significant reduction in endothelial proliferation and results in fewer branches/endothelial cells in the retinal vessels. Interestingly, venous endothelium appears to be more susceptible to ALK2 deletion. Mechanistically, ACVR1/ALK2 inhibits the expression of CDKN1A/p21, a critical negative regulator of cell cycle progression, in a SMAD1/5-dependent manner, thereby enabling the venous endothelium to undergo active proliferation by suppressing CDKN1A/p21. Taken together, our findings show that BMP signaling mediated by ACVR1/ALK2 provides a critical yet previously underappreciated input to modulate the proliferation of venous endothelium, thereby fine-tuning the context of angiogenesis in health and disease.
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The interactions between vascular cells, especially endothelial cells, and macrophages play a pivotal role in maintaining the subtle balance of vascular biology, which is crucial for angiogenesis in both healthy and diseased states. These cells are central to ensuring a harmonious balance between tissue repair and preventing excessive angiogenic activity, which could lead to pathological conditions. Recent advances in sophisticated genetic engineering vivo models and novel sequencing approaches, such as single-cell RNA-sequencing, in immunobiology have significantly enhanced our understanding of the gene expression and behavior of macrophages. These insights offer new perspectives on the role macrophages play not only in development but also across various health conditions. In this review, we explore the complex interactions between multiple types of macrophages and endothelium, focusing on their impact on new blood vessel formation. By understanding these intricate interactions, we aim to provide insights into new methods for managing angiogenesis in various diseases, thereby offering hope for the development of novel therapeutic approaches.
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Endothelial-to-mesenchymal transition (EndMT), a process initiated by activation of endothelial TGF-ß signaling, underlies numerous chronic vascular diseases and fibrotic states. Once induced, EndMT leads to a further increase in TGF-ß signaling, thus establishing a positive-feedback loop with EndMT leading to more EndMT. Although EndMT is understood at the cellular level, the molecular basis of TGF-ß-driven EndMT induction and persistence remains largely unknown. Here, we show that metabolic modulation of the endothelium, triggered by atypical production of acetate from glucose, underlies TGF-ß-driven EndMT. Induction of EndMT suppresses the expression of the enzyme PDK4, which leads to an increase in ACSS2-dependent Ac-CoA synthesis from pyruvate-derived acetate. This increased Ac-CoA production results in acetylation of the TGF-ß receptor ALK5 and SMADs 2 and 4 leading to activation and long-term stabilization of TGF-ß signaling. Our results establish the metabolic basis of EndMT persistence and unveil novel targets, such as ACSS2, for the potential treatment of chronic vascular diseases.
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Células Endoteliales , Enfermedades Vasculares , Humanos , Células Endoteliales/metabolismo , Transducción de Señal , Endotelio/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Enfermedades Vasculares/metabolismoRESUMEN
Understanding development of the cerebral vasculature is essential for the central nervous system (CNS) research and therapeutic developments. Here, we developed a simple, convenient, and fast method-the flattened cortex whole mount (FCWM) technique-for imaging of pial cerebral vessels. FCWM involves dissection of the whole cerebral cortex followed by flattening, sectioning and application of CLARITY technology. Compared to conventional methods, FCWM offers several advantages including (1) high-resolution visualization of the whole cortex pial surface vessel structures and distributions; (2) precise localization of a particular blood vessel, allowing observations of a desired blood vessel during normal development or in disease settings; (3) compatibility with confocal imaging. Application of FCWM for examination of cerebral vasculature during postnatal development or in stroke settings allowed us to demonstrate that cerebral blood vessels manifest type-specific maturation and remodeling which are linked to the rate of endothelial proliferation.
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AIMS: Components of bone morphogenetic protein (BMP) signalling have been implicated in both pathogenesis of pulmonary arterial hypertension (PAH) and endothelial-mesenchymal transition (EndoMT). In particular, the importance of BMP type 2 receptor in these processes has been extensively analysed. However, the contribution of BMP type 1 receptors (BMPR1s) to the onset of PAH and EndoMT remains poorly understood. BMPR1A, one of BMPR1s, was recently implicated in the pathogenesis of PAH, and was found to be down-regulated in the lungs of PAH patients, neither the downstream mechanism nor its contribution to EndoMT has been described. Therefore, we aim to delineate the role of endothelial BMPR1A in modulating EndoMT and pathogenesis of PAH. METHODS AND RESULTS: We find that BMPR1A knockdown in endothelial cells (ECs) induces hallmarks of EndoMT, and deletion of endothelial Bmpr1a in adult mice (Bmpr1aiECKO) leads to development of PAH-like symptoms due to excessive EndoMT. By lineage tracing, we show that endothelial-derived smooth muscle cells are increased in endothelial Bmpr1a-deleted mice. Mechanistically, we identify ZEB1 as a primary target for BMPR1A in this setting; upon BMPR1A activation, ID2 physically interacts and sequesters ZEB1 to attenuate transcription of Tgfbr2, which in turn lowers the responses of ECs towards transforming growth factor beta (TGFß) stimulation and prevents excessive EndoMT. In Bmpr1aiECKO mice, administering endothelial targeting lipid nanoparticles containing siRNA against Tgfbr2 effectively ameliorate PAH, reiterating the importance of BMPR1A-ID2/ZEB1-TGFBR2 axis in modulating progression of EndoMT and pathogenesis of PAH. CONCLUSIONS: We demonstrate that BMPR1A is key to maintain endothelial identity and to prevent excessive EndoMT. We identify BMPR1A-induced interaction between ID2 and ZEB1 is the key regulatory step for onset of EndoMT and pathogenesis of PAH. Our findings indicate that BMPR1A-ID2/ZEB1-TGFBR2 signalling axis could serve as a potential novel therapeutic target for PAH and other EndoMT-related vascular disorders.
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Receptores de Proteínas Morfogenéticas Óseas de Tipo 1 , Hipertensión Pulmonar , Proteína 2 Inhibidora de la Diferenciación , Hipertensión Arterial Pulmonar , Homeobox 1 de Unión a la E-Box con Dedos de Zinc , Animales , Ratones , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/genética , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/metabolismo , Células Endoteliales/metabolismo , Endotelio/metabolismo , Transición Epitelial-Mesenquimal , Hipertensión Pulmonar/metabolismo , Pulmón/metabolismo , Hipertensión Arterial Pulmonar/metabolismo , Receptor Tipo II de Factor de Crecimiento Transformador beta/metabolismo , Proteína 2 Inhibidora de la Diferenciación/metabolismo , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/metabolismoRESUMEN
We report a species of diplostomid fluke recovered from 3 carcasses of wild Korean raccoon dog, Nyctereutes procyonoides koreensis, in Korea. A total of 107 diplostomid flukes were recovered from the small intestines of Korean raccoon dogs, which were obtained from the Gangwon Wildlife Medical Rescue Center. Worms fixed with 10% neutral formalin were subjected to microscopic observation and those fixed in 70% ethanol were used for molecular genomic analysis. The worm was divided into 2 separate parts, forebody and hindbody, with a total length of 3,020-4,090 (3,855) µm and a width of 1,210-1,770 (1,562) µm. The boat-shaped forebody has a pair of characteristic tentacular appendage, 2 suckers, holdfast organ, and vitelline follicles. The oval to cylindrical hindbody has reproductive organs. The ovary was round or elliptical and located in the anterior of the testes. Two large testes were slightly segmented and tandemly arranged, occupying almost half of hindbody. The short uterus contained a relatively small number of unembryonated eggs sized 130-140×85-96 µm. The partial sequence of 18S rRNA of this fluke was consistent with Alaria alata. Based on the morphological and molecular characteristics, the diplostomid flukes recovered from the small intestine of Korean raccoon dogs were identified as A. alata (Digenea: Diplostomidae).
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Perros Mapache , Trematodos , Animales , Femenino , Animales Salvajes , Trematodos/genética , República de Corea , ARN Ribosómico 18SRESUMEN
In our previous study, we reported the isolation of pennogenin-3-O-α-L-rhamnopyranosyl-(1â2)-[α-L-rhamnopyranosyl-(1â3)]-ß-D-glucopyranoside (spiroconazol A), a steroidal saponin, from the flowers of Dioscorea bulbifera L. var. sativa. In the present study, we aimed to investigate the effects of spiroconazol A on autophagy and its underlying mechanisms in A549 and NCI-H358 human non-small cell lung cancer (NSCLC) cells. Spiroconazol A inhibited the proliferation of NSCLC cells in a concentration- and time-dependent manner. To determine the type of programmed cell death induced by spiroconazol A, we performed a characterization of apoptosis in spiroconazol A-treated A549 cells. Our results showed that spiroconazol A significantly suppressed A549 cell viability but did not influence cell apoptosis because phosphatidylserine and caspase activation were not detected. Furthermore, spiroconazol A treatment upregulated the expression of LC3-II and autophagy-related Beclin-1 protein, suggesting that spiroconazol A induces autophagy in A549 cells. Moreover, spiroconazol A activated the phosphorylation of p38 mitogen-activated protein kinase (MAPK) but did not affect the phosphorylation of Janus kinase or ERK1/2. Notably, SB203580, a p38 MAPK inhibitor, had a significant inhibitory effect on spiroconazol A-induced autophagic cell death in A549 cells. Our results indicated that spiroconazol A-induced autophagy is dependent on p38 MAPK signaling and has potential as a therapeutic target in NSCLC.
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Systemic and pulmonary circulations constitute a complex organ that serves multiple important biological functions. Consequently, any pathological processing affecting the vasculature can have profound systemic ramifications. Endothelial and smooth muscle are the two principal cell types composing blood vessels. Critically, endothelial proliferation and migration are central to the formation and expansion of the vasculature both during embryonic development and in adult tissues. Endothelial populations are quite heterogeneous and are both vasculature type- and organ-specific. There are profound molecular, functional, and phenotypic differences between arterial, venular and capillary endothelial cells and endothelial cells in different organs. Given this endothelial cell population diversity, it has been challenging to determine the origin of endothelial cells responsible for the angiogenic expansion of the vasculature. Recent technical advances, such as precise cell fate mapping, time-lapse imaging, genome editing, and single-cell RNA sequencing, have shed new light on the role of venous endothelial cells in angiogenesis under both normal and pathological conditions. Emerging data indicate that venous endothelial cells are unique in their ability to serve as the primary source of endothelial cellular mass during both developmental and pathological angiogenesis. Here, we review recent studies that have improved our understanding of angiogenesis and suggest an updated model of this process.
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Células Endoteliales , Neovascularización Fisiológica , Diferenciación Celular , Células Endoteliales/citología , Humanos , Neovascularización PatológicaRESUMEN
Endothelial cells differ from other cell types responsible for the formation of the vascular wall in their unusual reliance on glycolysis for most energy needs, which results in extensive production of lactate. We find that endothelium-derived lactate is taken up by pericytes, and contributes substantially to pericyte metabolism including energy generation and amino acid biosynthesis. Endothelial-pericyte proximity is required to facilitate the transport of endothelium-derived lactate into pericytes. Inhibition of lactate production in the endothelium by deletion of the glucose transporter-1 (GLUT1) in mice results in loss of pericyte coverage in the retina and brain vasculatures, leading to the blood-brain barrier breakdown and increased permeability. These abnormalities can be largely restored by oral lactate administration. Our studies demonstrate an unexpected link between endothelial and pericyte metabolisms and the role of endothelial lactate production in the maintenance of the blood-brain barrier integrity. In addition, our observations indicate that lactate supplementation could be a useful therapeutic approach for GLUT1 deficiency metabolic syndrome patients.
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Barrera Hematoencefálica , Pericitos , Animales , Barrera Hematoencefálica/metabolismo , Células Endoteliales/metabolismo , Endotelio/metabolismo , Transportador de Glucosa de Tipo 1/genética , Transportador de Glucosa de Tipo 1/metabolismo , Humanos , Ácido Láctico/metabolismo , Ratones , Pericitos/metabolismoRESUMEN
Cancer cells can develop an immunosuppressive tumor microenvironment to control tumor-infiltrating lymphocytes. The underlying mechanisms still remain unclear. Here, we report that mouse and human colon cancer cells acquire lymphocyte membrane proteins including cellular markers such as CD4 and CD45. We observed cell populations harboring both a tumor-specific marker and CD4 in the tumor microenvironment. Sorted cells from these populations were capable of forming organoids, identifying them as cancer cells. Live imaging analysis revealed that lymphocyte membrane proteins were transferred to cancer cells via trogocytosis. As a result of the transfer in vivo, cancer cells also acquired immune regulatory surface proteins such as CTLA4 and Tim3, which suppress activation of immune cells [T. L. Walunas et al, Immunity 1, 405-413 (1994) and L. Monney et al., Nature 415, 536-541 (2002)]. RNA sequencing analysis of ex vivo-cocultured splenocytes with trogocytic cancer cells showed reductions in Th1 activation and natural killer cell signaling pathways compared with the nontrogocytic control. Cancer cell trogocytosis was confirmed in the patient-derived xenograft models of colorectal cancer and head and neck cancer. These findings suggest that cancer cells utilize membrane proteins expressed in lymphocytes, which in turn contribute to the development of the immunosuppressive tumor microenvironment.
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Linfocitos T CD4-Positivos/citología , Antígeno CTLA-4/metabolismo , Neoplasias del Colon/inmunología , Neoplasias del Colon/metabolismo , Linfocitos Infiltrantes de Tumor/citología , Animales , Células CACO-2 , Membrana Celular/metabolismo , Células Cultivadas , Técnicas de Cocultivo , Células Madre Hematopoyéticas/citología , Humanos , Sistema Inmunológico , Inmunosupresores , Células Jurkat , Células Asesinas Naturales/inmunología , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Organoides/metabolismo , Transducción de Señal/inmunología , Linfocitos T Reguladores/inmunología , Trogocitosis , Microambiente TumoralRESUMEN
BACKGROUND: Angiogenesis is a dynamic process that involves expansion of a preexisting vascular network that can occur in a number of physiological and pathological settings. Despite its importance, the origin of the new angiogenic vasculature is poorly defined. In particular, the primary subtype of endothelial cells (capillary, venous, arterial) driving this process remains undefined. METHODS: Endothelial cells were fate-mapped with the use of genetic markers specific to arterial and capillary cells. In addition, we identified a novel venous endothelial marker gene (Gm5127) and used it to generate inducible venous endothelium-specific Cre and Dre driver mouse lines. Contributions of these various types of endothelial cells to angiogenesis were examined during normal postnatal development and in disease-specific setting. RESULTS: Using a comprehensive set of endothelial subtype-specific inducible reporter mice, including tip, arterial, and venous endothelial reporter lines, we showed that venous endothelial cells are the primary endothelial subtype responsible for the expansion of an angiogenic vascular network. During physiological angiogenesis, venous endothelial cells proliferate, migrating against the blood flow and differentiating into tip, capillary, and arterial endothelial cells of the new vasculature. Using intravital 2-photon imaging, we observed venous endothelial cells migrating against the blood flow to form new blood vessels. Venous endothelial cell migration also plays a key role in pathological angiogenesis. This was observed both in formation of arteriovenous malformations in mice with inducible endothelium-specific Smad4 deletion mice and in pathological vessel growth seen in oxygen-induced retinopathy. CONCLUSIONS: Our studies establish that venous endothelial cells are the primary endothelial subtype responsible for normal expansion of vascular networks, formation of arteriovenous malformations, and pathological angiogenesis. These observations highlight the central role of the venous endothelium in normal development and disease pathogenesis.
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Células Endoteliales/metabolismo , Animales , Humanos , Ratones , Ratones Transgénicos , Neovascularización PatológicaRESUMEN
Bone Morphogenetic Protein (BMP) signaling regulates diverse biological processes. Upon ligand binding, BMP receptors (BMPRs) phosphorylate SMAD1/5 and other noncanonical downstream effectors to induce transcription of downstream targets. However, the precise role of individual BMP receptors in this process remains largely unknown due to the complexity of downstream signaling and the innate promiscuity of ligand-receptor interaction. To delineate unique downstream effectors of individual BMPR1s, we analyzed the transcriptome of human umbilical endothelial cells (HUVECs) expressing three distinct constitutively active BMPR1s of which expression was detected in endothelial cells (ECs). From our analyses, we identified a number of novel downstream targets of BMPR1s in ECs. More importantly, we found that each BMPR1 possesses a distinctive set of downstream effectors, suggesting that each BMPR1 is likely to retain unique function in ECs. Taken together, our analyses suggest that each BMPR1 regulates downstream targets non-redundantly in ECs to create context-dependent outcomes of the BMP signaling.
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Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/fisiología , Perfilación de la Expresión Génica/métodos , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Receptores de Activinas Tipo I/genética , Animales , Células Cultivadas , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Proteína Smad1/fisiología , Proteína Smad5/fisiologíaRESUMEN
Total 513 heterophyid flukes were collected from a carcass of wild Korean raccoon dog, Nyctereutes procyonoides koreensis, in Korea. With morphological and molecular characteristics, the flukes were identified to Cryptocotyle lata. The adult C. lata were minute, transparent, pentagonal, 522 µm long by 425 µm wide. Ceca extended into post-testicular region. Ventrogenital sac elliptical, 79 µm by 87 µm with genital pore and ventral sucker. Two testes semielliptical and slightly lobed, located in the posterior region, right testis 173 µm by 155 µm, left testis 130 µm by 134 µm. In a phylogenetic tree, the fluke specimen of this study was grouped with C. lata divergent from Cryptocotyle lingua. We report here N. procyonoides koreensis first as a natural definitive host of C. lata.
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Heterophyidae , Trematodos , Animales , Masculino , Filogenia , Perros Mapache , República de Corea , Trematodos/genéticaRESUMEN
To mitigate cyanobacterial blooms, the naphthoquinone derivative, NQ 2-0, which has selective algicidal activity against cyanobacteria, has been developed. However, due to a lack of information on its algicidal mechanisms, there are significant gaps in our understanding of how this substance is capable of selectively killing cyanobacteria. Here, we investigated the selective algicidal mechanisms of NQ 2-0 using target (Microcystis aeruginosa) and non-target (Cyclotella sp. and Selenastrum capricornutum) species. NQ 2-0 showed selective algicidal activity against only M. aeruginosa, and this activity was strongly light-dependent. This NQ compound has selectively reduced the oxygen evolution rate and photosystem II (PSII) efficiency of M. aeruginosa throughout blocking electron transfer from the photosynthetic electron transport system, and significantly (p ≤ 0.05) increased levels of reactive oxygen species (ROS), resulting in membrane damage through lipid peroxidation. In ultrastructural observations, thylakoid membranes were disintegrated within 12 h after NQ 2-0 treatment, and cytoplasmic vacuolation and disintegrated cellular membrane were observed at 24 h. These findings suggest that increased ROS levels following NQ 2-0 treatment may induce cell death. Interestingly, compared to non-target eukaryotic cells, M. aeruginosa showed relatively late antioxidant response to reduce the increased ROS level, this may enhance algicidal activity against this cyanobacterium.
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Herbicidas , Peroxidación de Lípido/efectos de los fármacos , Microcystis/metabolismo , Naftoquinonas , Complejo de Proteína del Fotosistema II/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Herbicidas/farmacología , Naftoquinonas/química , Naftoquinonas/farmacologíaRESUMEN
The blood and lymphatic vasculatures are vital to the maintenance of homeostasis. The interaction between two vascular networks throughout the body is precisely controlled to enable oxygen and nutrient delivery, removal of carbon dioxide and metabolic waste, drainage of interstitial fluid, transport of immune cells, and other key activities. Recent years have seen an explosion of information dealing with the development and function of the lymphatic system. The growth of lymphatic vessels, termed lymphangiogenesis, is a high-energy requirement process that involves sprouting, proliferation, migration, and remodeling of lymphatic endothelial cells and capillaries. Although there has been substantial progress in identifying growth factors and their downstream signaling pathways that control lymphangiogenesis, the role of metabolic processes during lymphangiogenesis and their links to growth factor signaling are poorly understood. In this review, we will discuss recent work that has provided new insights into lymphatic metabolism and its role in lymphangiogenesis.
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Lymphangiogenesis is an important developmental process that is critical to regulation of fluid homeostasis, immune surveillance and response as well as pathogenesis of a number of diseases, among them cancer, inflammation, and heart failure. Specification, formation, and maturation of lymphatic blood vessels involves an interplay between a series of events orchestrated by various transcription factors that determine expression of key genes involved in lymphangiogenesis. These are traditionally thought to be under control of several key growth factors including vascular growth factor-C (VEGF-C) and fibroblast growth factors (FGFs). Recent insights into VEGF and FGF signaling point to their role in control of endothelial metabolic processes such as glycolysis and fatty acid oxidation that, in turn, play a major role in regulation of lymphangiogenesis. These advances have significantly increased our understanding of lymphatic biology and opened new therapeutic vistas. Here we review our current understanding of metabolic controls in the lymphatic vasculature.
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Células Endoteliales/metabolismo , Linfangiogénesis/fisiología , Animales , Humanos , Vasos Linfáticos/metabolismo , Factores de Transcripción/metabolismoRESUMEN
BACKGROUND: Bone morphogenetic protein (BMP) signaling has multiple roles in the development and function of the blood vessels. In humans, mutations in BMP receptor type 2 (BMPR2), a key component of BMP signaling, have been identified in the majority of patients with familial pulmonary arterial hypertension (PAH). However, only a small subset of individuals with BMPR2 mutation develops PAH, suggesting that additional modifiers of BMPR2 function play an important role in the onset and progression of PAH. METHODS: We used a combination of studies in zebrafish embryos and genetically engineered mice lacking endothelial expression of Vegfr3 to determine the interaction between vascular endothelial growth factor receptor 3 (VEGFR3) and BMPR2. Additional in vitro studies were performed by using human endothelial cells, including primary lung endothelial cells from subjects with PAH. RESULTS: Attenuation of Vegfr3 in zebrafish embryos abrogated Bmp2b-induced ectopic angiogenesis. Endothelial cells with disrupted VEGFR3 expression failed to respond to exogenous BMP stimulation. Mechanistically, VEGFR3 is physically associated with BMPR2 and facilitates ligand-induced endocytosis of BMPR2 to promote phosphorylation of SMADs and transcription of ID genes. Conditional, endothelial-specific deletion of Vegfr3 in mice resulted in impaired BMP signaling responses, and significantly worsened hypoxia-induced pulmonary hypertension. Consistent with these data, we found significant decrease in VEGFR3 expression in pulmonary arterial endothelial cells from human PAH subjects, and reconstitution of VEGFR3 expression in PAH pulmonary arterial endothelial cells restored BMP signaling responses. CONCLUSIONS: Our findings identify VEGFR3 as a key regulator of endothelial BMPR2 signaling and a potential determinant of PAH penetrance in humans.
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Receptores de Proteínas Morfogenéticas Óseas de Tipo II/biosíntesis , Endotelio Vascular/metabolismo , Hipertensión Pulmonar/metabolismo , Receptor 3 de Factores de Crecimiento Endotelial Vascular/biosíntesis , Animales , Receptores de Proteínas Morfogenéticas Óseas de Tipo II/genética , Células Cultivadas , Endotelio Vascular/patología , Humanos , Hipertensión Pulmonar/genética , Hipertensión Pulmonar/patología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Receptor 3 de Factores de Crecimiento Endotelial Vascular/genética , Pez CebraRESUMEN
OBJECTIVE: Increasing evidence suggests that bone morphogenetic protein (BMP) signaling regulates angiogenesis. Here, we aimed to define the function of BMP receptors in regulating early postnatal angiogenesis by analysis of inducible, endothelial-specific deletion of the BMP receptor components Bmpr2 (BMP type 2 receptor), Alk1 (activin receptor-like kinase 1), Alk2, and Alk3 in mouse retinal vessels. APPROACH AND RESULTS: Expression analysis of several BMP ligands showed that proangiogenic BMP ligands are highly expressed in postnatal retinas. Consistently, BMP receptors are also strongly expressed in retina with a distinct pattern. To assess the function of BMP signaling in retinal angiogenesis, we first generated mice carrying an endothelial-specific inducible deletion of Bmpr2. Postnatal deletion of Bmpr2 in endothelial cells substantially decreased the number of angiogenic sprouts at the vascular front and branch points behind the front, leading to attenuated radial expansion. To identify critical BMPR1s (BMP type 1 receptors) associated with BMPR2 in retinal angiogenesis, we generated endothelial-specific inducible deletion of 3 BMPR1s abundantly expressed in endothelial cells and analyzed the respective phenotypes. Among these, endothelial-specific deletion of either Alk2/acvr1 or Alk3/Bmpr1a caused a delay in radial expansion, reminiscent of vascular defects associated with postnatal endothelial-specific deletion of BMPR2, suggesting that ALK2/ACVR1 and ALK3/BMPR1A are likely to be the critical BMPR1s necessary for proangiogenic BMP signaling in retinal vessels. CONCLUSIONS: Our data identify BMP signaling mediated by coordination of ALK2/ACVR1, ALK3/BMPR1A, and BMPR2 as an essential proangiogenic cue for retinal vessels.
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Receptores de Activinas Tipo I/metabolismo , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/metabolismo , Proteínas Morfogenéticas Óseas/metabolismo , Células Endoteliales/efectos de los fármacos , Arteria Retiniana/efectos de los fármacos , Neovascularización Retiniana , Receptores de Activinas Tipo I/deficiencia , Receptores de Activinas Tipo I/genética , Receptores de Activinas Tipo II , Animales , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/deficiencia , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/genética , Receptores de Proteínas Morfogenéticas Óseas de Tipo II/deficiencia , Receptores de Proteínas Morfogenéticas Óseas de Tipo II/genética , Células Endoteliales/metabolismo , Regulación del Desarrollo de la Expresión Génica , Genotipo , Ligandos , Ratones Endogámicos C57BL , Ratones Noqueados , Fenotipo , Arteria Retiniana/metabolismo , Transducción de SeñalRESUMEN
Angiogenesis is regulated by the dynamic interaction between endothelial cells (ECs). Hippo-Yes-associated protein (YAP) signalling has emerged as a key pathway that controls organ size and tissue growth by mediating cell contact inhibition. However, the role of YAP in EC has not been defined yet. Here, we show expression of YAP in the developing front of mouse retinal vessels. YAP subcellular localization, phosphorylation and activity are regulated by VE-cadherin-mediated-EC contacts. This VE-cadherin-dependent YAP phosphorylation requires phosphoinositide 3-kinase-Akt activation. We further identify angiopoietin-2 (ANG-2) as a potential transcriptional target of YAP in regulating angiogenic activity of EC in vitro and in vivo. Overexpression of YAP-active form in EC enhances angiogenic sprouting, and this effect is blocked by ANG-2 depletion or soluble Tie-2 treatment. These findings implicate YAP as a critical regulator in angiogenesis and provide new insights into the mechanism coordinating junctional stability and angiogenic activation of ECs.