Posts Tagged: endothelial cells

Autophagy and Mitophagy in Cardiovascular Disease

Autophagy and Mitophagy in Cardiovascular Disease

José Manuel Bravo-San Pedro, Guido Kroemer, Lorenzo Galluzzi

Detrimental effects of autophagy or mitophagy inhibition on cardiovascular health. Multiple genetic interventions that limit autophagic or mitophagic flux at the whole-body level or in specific compartments of the cardiovascular system have been associated with the spontaneous development of cardiovascular disorders. AP indicates autophagosome; APL, autophagolysosome; Atg5, autophagy related 5; Bnip3l, BCL2 interacting protein 3 like; Dnml1, dynamin 1 like; Fbxo32, F-box protein 32; L, lysosome; Lamp2, lysosomal-associated membrane protein 2; Mfn1, mitofusin 1; Park2, Parkinson disease (autosomal recessive, juvenile) 2, parkin; Pink1, PTEN-induced putative kinase 1; Sirt6, sirtuin 6; Tfrc, transferrin receptor; and Trp53, transformation-related protein 53. [Powerpoint File]

Extracellular Vesicles in Angiogenesis

Extracellular Vesicles in Angiogenesis

Dilyana Todorova, Stéphanie Simoncini, Romaric Lacroix, Florence Sabatier, Françoise Dignat-George

Mechanisms involved in the modulation of Angiogenesis by endothelial cell (EC)–derived extracellular vesicles (EVs). EC release EVs rich in micro-RNA such as miR-214 and miR-126, that are transferred to recipient EC and induce proangiogenic signaling. EVs contain functional matrix metalloproteinases that facilitate angiogenesis through the degradation of components of the extracellular matrix. Dll4 is transferred to EC by the EVs and induces Notch receptor internalization and tip cell formation. EVs bear, at their surface, a tissue factor that interacts with β1 integrin and induces Rac1-ERK1/2-ETS1 signaling, leading to the increased secretion of CCL2. EVs transport the complex uPA/uPAR, which stimulates angiogenesis through plasmin generation. The phosphatidylserine present on the surface of the EVs interacts with CD36 and induces Fyn kinase signaling, which leads to increased oxidative stress and the inhibition of angiogenesis. ATM indicates ataxia telangiectasia mutated; CCl2, chemokine c-c motif ligand 2; Dll4, Delta-like 4; ECM, extracellular matrix; ERK1/2, extracellular signal-related kinase 1 and 2; ETS1, avian erythroblastosis virus E26 homolog-1; IL-3R, interleukin-3 receptor; MMPs, matrix metalloproteinases; NotchR, Notch receptor; PS, phosphatidylserine; Rac1, Ras-related C3 botulinum toxin substrate 1; ROS, reactive oxygen species; TF, tissue factor; TIMPS, tissue inhibitor of metalloproteinases; uPA, urokinase plasminogen activator; and uPAR, urokinase plasminogen activator receptor. [Powerpoint File]

Extracellular Vesicles in Angiogenesis

Extracellular Vesicles in Angiogenesis

Dilyana Todorova, Stéphanie Simoncini, Romaric Lacroix, Florence Sabatier, Françoise Dignat-George

Mechanisms involved in the modulation of Angiogenesis by platelet-derived extracellular vesicles (EVs). Platelet-derived EVs contain various growth factors and chemokines that induce proangiogenic signaling in endothelial cell (EC). Spingosine-1-phosphate (S1P1), present on the EV surface, induces PI3K activation and, together with VEGF and bFGF, promotes angiogenesis. The EVs released by platelets stimulate the proangiogenic potential of circulating angiogenic cells by increasing their expression of both membrane molecules and soluble factors. Platelet-derived EVs can inhibit angiogenesis by transferring the p22phox and gp91 subunits of NADPH oxidase and increasing the oxidative stress in EC. ? indicates that the exact content of the EVs is not reported; bFGF, basic fibroblast growth factor; EGF, epidermal growth factor; GM-CSF, granulocyte-macrophage colony-stimulating factor; HGF, hepatocyte growth factor; NADPH, nicotinamide adenine dinucleotide phosphate; PI3K, phosphoinositide 3-kinase; RANTES, regulated on activation, normal T-cell–expressed and secreted; ROS, reactive oxygen species; VEGF, vascular endothelial growth factor; and VEGFR, vascular endothelial growth factor receptor. [Powerpoint FIle]

Contemporary Approaches to Modulating the Nitric Oxide–cGMP Pathway in Cardiovascular Disease

Contemporary Approaches to Modulating the Nitric Oxide–cGMP Pathway in Cardiovascular Disease

Jan R. Kraehling, William C. Sessa

Proteins and enzymes involved in the nitric oxide (NO)-nitric oxide–sensitive guanylate cyclase (NOsGC)–cGMP pathway and its modulators. Key players of the pathway are shown in blue, the positive modulators are shown in yellow, and the negative modulators in purple. Endothelial cells (EC) are shown in green (top), whereas the vascular smooth muscle cell (VSMC) is shown in red (bottom). The space between the 2 cells is called myoendothelial junction (MEJ). cGMP mediates its cellular functions through cGMP-modulated (cyclic nucleotide-gated [CNG]) cation channels, cGMP-dependent protein kinases (cGKs) and cGMP-regulated phosphodiesterases (PDEs). BH4 indicates tetrahydrobiopterin; CAV1, caveolin-1; CYB5R3, NADH-cytochrome b5 reductase 3; eNOS, endothelial nitric oxide synthase (NOS3); Hb2+/Hb3+, hemoglobin α (reduced/oxidized); and PDE, phosphodiesterase. [Powerpoint File]

Contemporary Approaches to Modulating the Nitric Oxide–cGMP Pathway in Cardiovascular Disease

Contemporary Approaches to Modulating the Nitric Oxide–cGMP Pathway in Cardiovascular Disease

Jan R. Kraehling, William C. Sessa

Mechanism of action of nitric oxide–sensitive guanylate cyclase (NOsGC) stimulators and activators. NOsGC stimulators bind to the enzyme and act in an allosteric manner. NO and NOsGC stimulators enhance the NOsGC activity synergistically. NOsGC activators occupy the heme binding site and work therefore only additively with NO. The oxidation of the heme-Fe2+ to heme-Fe3+ results in a weaker binding of heme to NOsGC, hence allowing the NOsGC activators to occupy the heme binding site easier. The schematic is derived from Zorn and Wells.111 [Powerpoint File]

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

Yulia A. Komarova, Kevin Kruse, Dolly Mehta, Asrar B. Malik

Mechanotransduction at adherens junctions (AJs). The mechanosensory complex in endothelial cells is composed of vascular endothelial (VE)-cadherin, platelet endothelial cell adhesion molecule (PECAM)-1, and vascular endothelial growth factor receptor (VEGFR) 2. Mechanosensing of shear stress occurs through PECAM-1–dependent activation of Fyn, which in turn facilitates VEGFR2-mediated signaling in a ligand-independent manner and activates phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K). PI3K activates both Rac1 and endothelial nitric oxide synthase (eNOS) signaling pathways. Rac1 relieves tension at AJs, whereas NO concomitantly promotes vasorelaxation of smooth muscle cells. PECAM-1–dependent sensing of shear stress also promotes α2β1 integrin signaling and consequently activation of protein kinase A (PKA) in atheroresistant regions. PKA phosphorylates RhoA and decreases RhoA-dependent cellular stiffness allowing the endothelial cell to align in the direction of blood flow. GPCR indicates G-protein–coupled receptor; and sGC, soluble guanylyl cyclase. [Powerpoint File]

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

Yulia A. Komarova, Kevin Kruse, Dolly Mehta, Asrar B. Malik

Role of actomyosin apparatus in stabilizing adherens junctions (AJs). A, Domain structure of nonmuscle myosin-II (NM-II). The NM-II consists of a globular head domain containing both actin-binding and motor domains, essential light chains (ELCs), regulatory light chains (RLCs), and heavy chains. NM-II possesses a head-to-tail interaction in the absence of phosphorylation. Phosphorylation of regulatory light chain at Thr18/Ser19 by myosin light chain kinase (MLCK) unfolds the molecule, enabling assembly of antiparallel filaments through interactions between their rod domains. Activation of Rho-associated kinase (ROCK), which inhibits phosphatase activity of myosin light chain phosphatase (MLCP) in a phosphorylation-dependent manner, also favors RLC phosphorylation. NM-II filaments bind to actin filaments, which slide along each other, and cause a cell contraction. Modified from Vicente-Manzanares et al415 with permission of the publisher. Copyright ©2009, Nature Publishing Group. B, Proposed mechanism of regulation of NM-II activity at AJs in confluent endothelium. NM-II regulates attachment of the vascular endothelial (VE)-cadherin adhesion complex to the actin cytoskeleton, thereby generating mechanical tension required for binding of α-catenin to both β-catenin and f-actin. NM-II phosphorylation is controlled by MLCK and MLCP activities. In the model, we propose that Src and Cdc42 pathways cooperate in regulating NM-II activity at AJs. Cdc42 facilitates activation of NM-II through myotonic dystrophy kinase–related Cdc42-binding kinase (MRCK)–dependent phosphorylation of MLCP, whereas Src phosphorylates MLCK at sites of VE-cadherin adhesion. CaM indicates calmodulin; GAP, GTPase-activating protein; and GEF, guanine nucleotide exchange factor. [Powerpoint File]

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

Yulia A. Komarova, Kevin Kruse, Dolly Mehta, Asrar B. Malik

Composition of interendothelial junctions. A, Schematic representation of interendothelial junctions composed of tight junctions (TJs), adherens junctions (AJs), and gap junctions (GJs). TJs are mediated by adhesion proteins such as claudins, occludin, and junctional adhesion molecules (JAMs), whereas the zona occludin proteins (ZO-1, ZO-2, and ZO-3) connect adhesion molecules to the actin cytoskeleton. AJs are composed of vascular endothelial (VE)-cadherin and associated β- and p120-catenins. α-catenin binds β-catenin to connect AJs to the actin cytoskeleton. GJs are composed of 2 connexin hexamers forming hemichannels. B, VE-cadherin mediates adhesion by trans-dimerization of tryptophan 2 and tryptophan 4 residues in a hydrophobic pocket of the opposing VE-cadherin molecule. Ribbon presentations of VE-cadherin trans-dimer. C, Strand swap dimerization occurs through the insertion of a tryptophan residue into the hydrophobic binding pocket of the opposing cadherin. D, Trans-dimerization (between endothelial cell [EC] 1 and EC1 of opposing cadherins) orients VE-cadherin molecules and facilitates cis interactions (between EC1 and EC2 of neighboring cadherins). Panels B, C, and D are modified from Brasch et al115 with permission of the publisher. Copyright ©2012, Elsevier. [Powerpoint File]

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Michael A. Gimbrone Jr, Guillermo García-Cardeña

Endothelial-derived nitric oxide: production and biological actions. Endothelial cells rapidly produce nitric oxide (NO) via a unique isoform of NO synthase (eNOS) in response to agonists (eg, acetylcholine and bradykinin) and fluctuations in blood flow. Once generated, NO rapidly diffuses through the endothelial plasma membrane to activate guanylate cyclase in several cell types present in the blood (platelets and leukocytes) and also within the vessel wall (smooth muscle). Activation of guanylate cyclase in platelets results in inhibition of activation, adhesion, and aggregation; in leukocytes, decreased adhesivity; in smooth muscle cells, dephosphorylation of myosin light chain and vasorelaxation. NO also reacts with hemoglobin in erythrocytes, enhancing oxygen delivery to tissues. Chronic exposure of endothelial cells to laminar flow results in transcriptional upregulation of eNOS, thus increasing their NO-forming capacity (Illustration Credit: Ben Smith). [Powerpoint File]

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Michael A. Gimbrone Jr, Guillermo García-Cardeña

Endothelial proinflammatory activation. In lesion-prone regions of the arterial vasculature, the actions of proinflammatory agonists (eg, interleukin [IL]-1, tumor necrosis factor [TNF], and endotoxin), oxidized lipoproteins (ox-LDL) and advanced glycation end products (AGE), as well as biomechanical stimulation by disturbed blood flow, leads to endothelial activation. These biochemical and biomechanical stimuli signal predominantly via the pleiotropic transcription factor nuclear factor-κB (NF-κB), resulting in a coordinated program of genetic regulation within the endothelial cell. This includes the cell surface expression of adhesion molecules (eg, vascular cell adhesion molecule-1 [VCAM-1), secreted and membrane-associated chemokines (eg, monocyte chemotractant protein [MCP]-1 and fractalkine), and prothrombotic mediators (eg, tissue factor [TF], vonWillebrand Factor [vWF], and plasminogen activator inhibitor [PAI]-1). These events foster the selective recruitment of monocytes and various types of T lymphocytes, which become resident in the subendothelial space. The concerted actions of activated endothelial cells, smooth muscle cells, monocyte/macrophages, and lymphocytes result in the production of a complex paracrine milieu of cytokines, growth factors, and reactive oxygen species (ROS) within the vessel wall, which perpetuates a chronic proinflammatory state and fosters atherosclerotic lesion progression. IL-R, TNF-R indicates receptor(s) for IL-1, TNF; Ox-LDL-R, receptor for oxidized LDL; RAGE, receptor for AGE; and TLRs, Toll-like receptors (Illustration Credit: Ben Smith). [Powerpoint File]

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Michael A. Gimbrone Jr, Guillermo García-Cardeña

Hemodynamics and endothelial phenotypes. Computational analyses of in vivo blood flow patterns in the carotid artery bifurcation, in normal human subjects, yielded representative near-wall shear stress waveforms from 2 hemodynamically distinct, clinically relevant locations: the distal internal carotid (an atherosclerosis-resistant region) and the carotid sinus (an atherosclerosis-susceptible region). Exposure of cultured human endothelial monolayers to these 2 distinct biomechanical stimuli, resulted in markedly different cell morphologies (visualized here by cytoskeletal actin staining) and functional phenotypes. Pulsatile (unidirectional) laminar flow induced upregulation of key transcription factors (Kruppel-like factor [KLF]-2, KLF4, and nuclear factor erythroid 2-related factor [Nrf]-2), which orchestrated a multifunctional atheroprotective phenotype; in contrast, disturbed (oscillatory) flow resulted in enhanced expression of the pleiotropic transcription factor NF-κB, resulting in a proinflammatory, atheroprone phenotype.161 [Powerpoint File]

Lymphatic System in Cardiovascular Medicine

Lymphatic System in Cardiovascular Medicine

Aleksanteri Aspelund, Marius R. Robciuc, Sinem Karaman, Taija Makinen, Kari Alitalo

Mechanisms of VEGFC activation by CCBE1 and ADAMTS3. Paracrine CCBE1 secretion at sites of lymphatic vessel growth promotes the proteolytic cleavage of the poorly active 29/31 kDa form of VEGFC (pro-VEGFC) by the disintegrin/metalloprotease ADAMTS3 and possibly by other proteases. This results in the formation of a mature 21/23 kDa form of VEGFC that can fully activate VEGFR3. Although CCBE1 binds to extracellular matrix (ECM), most of the VEGFC cleavage may occur on lymphatic endothelial cell (LEC) surface. The phenotypes of the related gene-targeted mice are indicated. Image derived from Jeltsch et al.85 WT indicates wild-type. [Powerpoint File]

Lymphatic System in Cardiovascular Medicine

Lymphatic System in Cardiovascular Medicine

Aleksanteri Aspelund, Marius R. Robciuc, Sinem Karaman, Taija Makinen, Kari Alitalo

Lymphatic vessel role in fat absorption and adipose deposition. A, VEGFC is expressed in a subset of smooth muscle fibers in the intestinal villi and in the circular smooth muscle layer of the intestinal wall, as well as in the arterial SMCs. Vegfc deletion induces intestinal lymphatic vessel atrophy, reducing lipid absorption by the lacteal vessels and thus diet-induced obesity.149 VEGFC may also regulate the contraction of lacteal-associated smooth muscle fibers, which have an important role in lipid absorption.38,150 B, Lymph leakage in Prox1+/- mice leads to increased adipogenesis.43 [Powerpoint File]

Lymphatic System in Cardiovascular Medicine

Lymphatic System in Cardiovascular Medicine

Aleksanteri Aspelund, Marius R. Robciuc, Sinem Karaman, Taija Makinen, Kari Alitalo

Organization of the lymphatic vascular tree. A, In overview, the unidirectional lymphatic vascular system consists of (1) lymphatic capillaries, (2) collecting lymphatic vessels, (3) lymph nodes, and (4) the thoracic duct and right lymphatic trunk. B, Lymphatic capillaries absorb interstitial solutes, macromolecules, and immune cells that extravasate from the blood vascular system. Lymph formation is facilitated by the discontinuous basement membrane (red dashed line), and button-like endothelial junctions allow passive paracellular flow for lymph formation. Adapted from Baluk et al17 with permission. C, Collecting lymphatic vessels contain zipper-like junctions, lymphatic valves, and contractile smooth muscle cells (SMCs) that enable the unidirectional propulsion of lymph. D, Organization of the lymph node with afferent lymphatic vessels and a single efferent lymphatic vessel. E, Lymph drains into venous circulation through 4 distinct lymphovenous valves located where the internal jugular vein (IJV) and external jugular vein (EJV) drain into the subclavian vein (SCV). [Powerpoint File]

Lymphatic System in Cardiovascular Medicine

Lymphatic System in Cardiovascular Medicine

Aleksanteri Aspelund, Marius R. Robciuc, Sinem Karaman, Taija Makinen, Kari Alitalo

Development of the lymphatic vascular tree. A, The common cardinal vein (CCV) at E9.0. B, Specification of lymphatic endothelial cells (LECs) at E9.5, identified by PROX1 expression in the CCV, in the intersomitic veins and in the superficial plexus. C, Budding of initial LECs (iLECs) from the CCV at E10 to E10.25. D, Formation of the lymph sacs, comprising the primordial thoracic duct (pTD) and primordial longitudinal lymphatic vessel (PLLV) between E10.5 and E11.5. E, Two mechanisms of expansion of the lymphatic vascular tree: lymphangiogenesis and lymphvasculogenesis. F, Lymphatic vessel maturation and remodeling from E14.5 onward: recruitment of smooth muscle cell (SMC) coverage and valve formation. Panels A–D adapted from Hägerling et al59 with permission. Panel E derived from Stanczuk et al.55 BEC indicates blood endothelial cell. [Powerpoint File]