Posts in Category: Cellular Biology

Calcium and Excitation-Contraction Coupling in the Heart

Calcium and Excitation-Contraction Coupling in the Heart

David A. Eisner, Jessica L. Caldwell, Kornél Kistamás, Andrew W. Trafford

Structures involved in Ca cycling. A, Schematic diagram. This shows surface membrane, transverse tubule, sarcoplasmic reticulum (SR), and mitochondria, as well as the various channels and transporters mentioned in the text. B, High-resolution transverse section of a ventricular myocyte showing t-tubule network. Reprinted from Jayasinghe et al39 with permission of the publisher. Copyright ©2009, Biophysical Society. C, Cartoon of dyad emphasizing the major proteins involved in Ca cycling. B-AR indicates beta adrenoceptor; MCU, mitochondrial Ca uniporter; NCX, sodium–calcium exchange; NCLX, mitochondrial Na–Ca exchange; PMCA, plasma membrane Ca-ATPase; RyR, ryanodine receptor; and SERCA, sarco/endoplasmic reticulum Ca-ATPase. [Powerpoint File]

Extracellular Vesicles in Metabolic Syndrome

Extracellular Vesicles in Metabolic Syndrome

M. Carmen Martínez, Ramaroson Andriantsitohaina

Extracellular vesicles (EVs) participate in the development of atherosclerotic plaque. EVMP from smooth muscle cells (pink) induce endothelial dysfunction and macrophage infiltration in the vessel wall through the reactive oxygen species (ROS) production and p38 activation in endothelial cells. EVEXO derived from dendritic cells (blue) increase endothelial inflammation by activation of nuclear factor-κB (NF-κB) pathway and increasing expression of proinflammatory molecules, including vascular cell adhesion molecule (VCAM), intercellular adhesion molecule (ICAM1), and E-selectin. [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]

Extracellular Vesicles in Metabolic Syndrome

Extracellular Vesicles in Metabolic Syndrome

M. Carmen Martínez, Ramaroson Andriantsitohaina

Effects of extracellular vesicles (EVs) on blood vessel. EVMP from endothelial cells (dark pink) transfer miR-503 to pericytes and subsequently inhibit vascular endothelial growth factor (VEGF) expression, resulting in decreased migration and proliferation. EVEXO from smooth muscle cells (pink) induce downregulation of LC3 II, ATG5, and Beclin-1 expression in endothelial cells. EVEXO from macrophages (green) evoke intercellular adhesion molecule 1 (ICAM1) overexpression in endothelial cells and reduce level of miR-17. Also, macrophage foam cell–derived EVs favor both migration and adhesion of vascular smooth muscle cells by activating ERK (extracellular signal-regulated kinase) and Akt (protein kinase B/AKT) pathways and by transfer integrins β1 and α5 into vascular smooth muscle cells. EVMP from metabolic syndrome (MetS) patients act on smooth muscle cells and induce overexpression of inducible nitric oxide synthase (iNOS) and monocyte chemoattractant molecule (MCP)-1, leading to vascular hyporeactivity. Also, these EVMP directly act on endothelial cells evoking reduced nitric oxide (NO) production, enhanced cytosolic and mitochondrial reactive oxygen species (ROS) production, and unfolding protein response (UPR). All effects of EVMP from MetS patients are mediated by the interaction Fas/FasL. [Powerpoint File]

Extracellular Vesicles in Cardiovascular Disease: Potential Applications in Diagnosis, Prognosis, and Epidemiology

Extracellular Vesicles in Cardiovascular Disease: Potential Applications in Diagnosis, Prognosis, and Epidemiology

Felix Jansen, Georg Nickenig, Nikos Werner

Extracellular vesicles (EVs) as biomarker in different stages of coronary artery disease. Levels of circulating EVs are detectable in plasma of healthy subjects and are elevated in patients with cardiovascular risk factors or already present cardiovascular diseases. This figure summarizes EV surface markers from clinical studies, which showed increased circulating levels of endothelial-, platelet-, white blood cell–, and red blood cell–derived EVs in different stages of coronary artery disease from patients at risk to acute coronary syndromes (Illustration credit: Ben Smith). [Powerpoint File]

Methodological Guidelines to Study Extracellular Vesicles

Methodological Guidelines to Study Extracellular Vesicles

Frank A.W. Coumans, Alain R. Brisson, Edit I. Buzas, Françoise Dignat-George, Esther E.E. Drees, Samir El-Andaloussi, Costanza Emanueli, Aleksandra Gasecka, An Hendrix, Andrew F. Hill, Romaric Lacroix, Yi Lee, Ton G. van Leeuwen, Nigel Mackman, Imre Mäger, John P. Nolan, Edwin van der Pol, D. Michiel Pegtel, Susmita Sahoo, Pia R.M. Siljander, Guus Sturk, Olivier de Wever, Rienk Nieuwland

Working principle of common methods to isolate extracellular vesicles (EVs). Separation is based on size, density, and immunophenotype. Straight brackets: isolated EVs; yellow: soluble components; and blue: buffer. A, In differential centrifugation, separation is based on size, and large EVs (gray) collect earlier at the bottom of the tube and at lower g forces than small EVs (green). The soluble components are not affected by centrifugation, but non-EV particles such as lipoproteins and protein aggregates may copellet with EVs. B, In density gradient centrifugation, separation is based on density, and EVs will travel to their equilibrium density. Non-EV particles such as lipoproteins may coelute with EVs because of similar density or interaction. The soluble components with a high density relative to the gradient will collect at the bottom of the tube. C, Size exclusion chromatography uses a porous matrix (dotted circles) that separates on size. Soluble components and particles smaller than the size cutoff enter the porous matrix temporarily, whereas EVs and particles larger than the size cutoff do not enter the porous matrix. As a result, EVs and particles larger than the size cutoff elute before the soluble components and particles smaller than the size cut-off. D, In ultrafiltration, soluble proteins and particles smaller than the size cutoff (≈105 kDa) are pushed through the filter, and the EVs are collected at the filter. E, In immunocapture assays, EVs are captured based on their immunophenotype. EVs are captured using an monoclonal antibody (mAb) directed against an antigen exposed on the targeted (green) EVs only. F, In precipitation, addition of a precipitating agent induces clumping of EVs, non-EV particles, and soluble proteins. The clumps will sediment, and sedimentation can be accelerated by centrifugation. [Powerpoint File]

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Henry Gewirtz, Vasken Dilsizian

Diagrammatic representation of myocardial cell and potential targets of radiotracer imaging and mapping of the surface renin–angiotensin system. ACE indicates angiotensin-converting enzyme; AGT, angiotensinogen; Ang II, angiotensin II; AT1R, angiotensin II type 1 receptor; and AT2R, angiotensin II type 2 receptor. Reproduced with permission from Schindler and Dilsizian.61 Copyright © 2012, Elsevier. [Powerpoint File]

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Henry Gewirtz, Vasken Dilsizian

Myocyte metabolic pathways outlined for glucose and fatty acid metabolism with focus on the mitochondrion. The electron transport chain (ETC), complexes I–V, is a series of proton pumps. The last of which, complex V, supplies protons to a proton-sensitive ATPase and thereby generates ATP. CPT1,2 indicates carnitine palmitoyltransferase 1,2; FA, fatty acid; PDH, pyruvate dehydrogenase; and TCA, tricarboxylic acid (Krebs cycle). Reproduced with permission from Huss and Kelly.30 Copyright © 2005, American Society for Clinical Investigation. [Powerpoint File]

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Henry Gewirtz, Vasken Dilsizian

Key myocyte organelles and ion channels and their function under conditions of ischemia and reperfusion. Ischemia (left panel) causes influx of Ca2+ and decline in pH, both of which, if not severe, facilitate maintenance of closed mitochondrial permeability transition pore (mPTP). On reperfusion (right panel), key events include restoration of physiological pH, burst of reactive oxygen species (ROS) from mitochondria, release of Ca2+ from the sarcoplasmic reticulum (SR), and opening of mPTP which results in collapse of its Δψ. Reproduced with permission from Hausenloy and Yellon.27 Copyright © 2013, American Society for Clinical Investigation. [Powerpoint File]

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Leo E. Otterbein*, Roberta Foresti*, Roberto Motterlini*

Schematic representation of the heme oxygenase pathway. Heme, either derived from intracellular sources, such as hemoproteins and mitochondria, or from damaged tissues and red blood cell hemolysis (extracellular sources) is used by heme oxygenase enzymes (HO-1 and HO-2) to generate carbon monoxide (CO), biliverdin, and iron. Biliverdin is converted to bilirubin by biliverdin reductase (BVR), whereas iron is stored in the ferritin protein. Although heme oxygenase enzymes were initially localized in the endoplasmic reticulum, recent reports suggest that HO-1 can be found under certain conditions in other cellular compartments such as the nucleus.19 [Powerpoint File]

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Leo E. Otterbein*, Roberta Foresti*, Roberto Motterlini*

Interaction of carbon monoxide (CO) with mitochondria. CO at high concentrations is known to inhibit mitochondrial respiration by competing with oxygen for the binding to cytochrome c oxidase (complex IV). In contrast, controlled delivery of CO gas and CO-releasing moleculess at nontoxic concentrations can protect cardiac tissue by promoting mitochondrial biogenesis, uncoupling activity, and metabolic switch (see text for details). The molecular mechanism(s) underlying these effects remains to be defined. However, the interaction of CO with mitochondrial targets different from cytochrome c oxidase is likely as the electron transport chain contains other heme-complexes that may display distinct sensitivities to CO. ROS indicates reactive oxygen species. [Powerpoint File]

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Leo E. Otterbein*, Roberta Foresti*, Roberto Motterlini*

Heme release and cardiac repair. Ischemia-reperfusion injury leads to the sudden release of cellular contents including heme, mitochondrial DNA, and ATP. These cellular danger-associated molecular patterns (DAMPs) have each been shown to induce heme oxygenase-1 (HO-1). HO-1 expression and the subsequent generation CO, biliverdin (BV), and bilirubin (BR) target a variety of cell types that impact cellular repair and tissue regeneration. [Powerpoint File]

Mitochondrial Metabolism in Aging Heart

Mitochondrial Metabolism in Aging Heart

Edward J. Lesnefsky, Qun Chen, Charles L. Hoppel

Schematic of the interfibrillar mitochondrial defects in the aged heart. ETC indicates electron transport chain; IMM, mitochondrial inner membrane; NADH, nicotinamide adenine dinucleotide; PPL, phospholipid, proposed defect affecting subunit VIIa in complex IV; and Q, ubiquinone; Qo site, ubiquinol-binding site on cytochrome bl with proposed defect in Y132. Illustration credit, Ben Smith. [Powerpoint File]

Mitochondrial Metabolism in Aging Heart

Mitochondrial Metabolism in Aging Heart

Edward J. Lesnefsky, Qun Chen, Charles L. Hoppel

A schematic of a cardiomyocyte to highlight the location of subsarcolemmal (SSM) and interfibrillar mitochondria (IFM). Illustration credit: Ben Smith. [Powerpoint File]