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Nanomedicine (London, England) Dec 2023The impacts of synthetic high-density lipoprotein (sHDL) phospholipid components on anti-sepsis effects were investigated. sHDL composed with ApoA-I mimetic peptide...
The impacts of synthetic high-density lipoprotein (sHDL) phospholipid components on anti-sepsis effects were investigated. sHDL composed with ApoA-I mimetic peptide (22A) and different phosphatidylcholines were prepared and characterized. Anti-inflammatory effects were investigated and on lipopolysaccharide (LPS)-induced inflammation models. sHDLs composed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (22A-DMPC) most effectively neutralizes LPS, inhibits toll-like receptor 4 recruitment into lipid rafts, suppresses nuclear factor κB signaling and promotes activating transcription factor 3 activating. The lethal endotoxemia animal model showed the protective effects of 22A-DMPC. Phospholipid components affect the stability and fluidity of nanodiscs, impacting the anti-septic efficacy of sHDLs. 22A-DMPC presents the strongest LPS binding and anti-inflammatory effects and , suggesting a potential sepsis treatment.
Topics: Animals; Phospholipids; Lipopolysaccharides; Dimyristoylphosphatidylcholine; Lipoproteins, HDL; Inflammation; Anti-Inflammatory Agents
PubMed: 38197376
DOI: 10.2217/nnm-2023-0222 -
Nature Communications Jun 2023Calcium homeostasis modulator 1 (CALHM1) is a voltage-dependent channel involved in neuromodulation and gustatory signaling. Despite recent progress in the structural...
Calcium homeostasis modulator 1 (CALHM1) is a voltage-dependent channel involved in neuromodulation and gustatory signaling. Despite recent progress in the structural biology of CALHM1, insights into functional regulation, pore architecture, and channel blockade remain limited. Here we present the cryo-EM structure of human CALHM1, revealing an octameric assembly pattern similar to the non-mammalian CALHM1s and the lipid-binding pocket conserved across species. We demonstrate by MD simulations that this pocket preferentially binds a phospholipid over cholesterol to stabilize its structure and regulate the channel activities. Finally, we show that residues in the amino-terminal helix form the channel pore that ruthenium red binds and blocks.
Topics: Humans; Ruthenium Red; Phospholipids; Membrane Glycoproteins; Calcium Channels
PubMed: 37380652
DOI: 10.1038/s41467-023-39388-3 -
Atherosclerosis May 2022Oxidized phospholipids (OxPL) are key mediators of the pro-atherosclerotic effects of oxidized lipoproteins. They are particularly important for the pathogenicity of... (Review)
Review
Oxidized phospholipids (OxPL) are key mediators of the pro-atherosclerotic effects of oxidized lipoproteins. They are particularly important for the pathogenicity of lipoprotein(a) (Lp(a)), which is the preferred lipoprotein carrier of phosphocholine-containing OxPL in plasma. Indeed, elevated levels of OxPL-apoB, a parameter that almost entirely reflects the OxPL on Lp(a), are a potent risk factor for atherothrombotic diseases as well as calcific aortic valve stenosis. A substantial fraction of the OxPL on Lp(a) are covalently bound to the KIV domain of apo(a), and the strong lysine binding site (LBS) in this kringle is required for OxPL addition. Using apo(a) species lacking OxPL modification - by mutating the LBS - has allowed direct assessment of the role of apo(a) OxPL in Lp(a)-mediated pathogenesis. The OxPL on apo(a) account for numerous harmful effects of Lp(a) on monocytes, macrophages, endothelial cells, smooth muscle cells, and valve interstitial cells documented both in vitro and in vivo. In addition, the mechanisms underlying these effects have begun to be unraveled by identifying the cellular receptors that respond to OxPL, the intracellular signaling pathways turned on by OxPL, and the changes in gene and protein expression evoked by OxPL. The emerging picture is that the OxPL on Lp(a) are central to its pathobiology. The OxPL modification may explain why Lp(a) is such a potent risk factor for cardiovascular disease despite being present at concentrations an order of magnitude lower than LDL, and they account for the ability of elevated Lp(a) to cause both atherothrombotic disease and calcific aortic valve stenosis.
Topics: Aortic Valve; Aortic Valve Stenosis; Apolipoproteins A; Apoprotein(a); Calcinosis; Endothelial Cells; Humans; Lipoprotein(a); Oxidation-Reduction; Phospholipids
PubMed: 35606081
DOI: 10.1016/j.atherosclerosis.2022.04.001 -
Biochimica Et Biophysica Acta.... Oct 2023Flaviviruses encompass many important human pathogens, including Dengue, Zika, West Nile, Yellow fever, Japanese encephalitis, and Tick-borne encephalitis viruses as... (Review)
Review
Flaviviruses encompass many important human pathogens, including Dengue, Zika, West Nile, Yellow fever, Japanese encephalitis, and Tick-borne encephalitis viruses as well as several emerging viruses that affect millions of people worldwide. They enter cells by endocytosis, fusing their membrane with the late endosomal one in a pH-dependent manner, so membrane fusion is one of the main targets for obtaining new antiviral inhibitors. The envelope E protein, a class II membrane fusion protein, is responsible for fusion and contains different domains involved in the fusion mechanism, including the fusion peptide. However, other segments, apart from the fusion peptide, have been implicated in the mechanism of membrane fusion, in particular a segment containing a His residue supposed to act as a specific pH sensor. We have used atomistic molecular dynamics to study the binding of the envelope E protein segment containing the conserved His residue in its three different tautomer forms with a complex membrane mimicking the late-endosomal one. We show that this His-containing segment is capable of spontaneous membrane binding, preferentially binds electronegatively charged phospholipids and does not bind cholesterol. Since Flaviviruses have caused epidemics in the past, continue to do so and will undoubtedly continue to do so, this specific segment could characterise a new target that would allow finding effective antiviral molecules against DENV virus in particular and Flaviviruses in general.
Topics: Humans; Viral Envelope; Viral Envelope Proteins; Flavivirus; Zika Virus; Zika Virus Infection; Peptides; Dengue; Antiviral Agents; Phospholipids
PubMed: 37437754
DOI: 10.1016/j.bbamem.2023.184198 -
Journal of Lipid Research Feb 2024Ferroptosis is a novel cell death mechanism that is mediated by iron-dependent lipid peroxidation. It may be involved in atherosclerosis development. Products of...
Ferroptosis is a novel cell death mechanism that is mediated by iron-dependent lipid peroxidation. It may be involved in atherosclerosis development. Products of phospholipid oxidation play a key role in atherosclerosis. 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) is a phospholipid oxidation product present in atherosclerotic lesions. It remains unclear whether PGPC causes atherosclerosis by inducing endothelial cell ferroptosis. In this study, human umbilical vein endothelial cells (HUVECs) were treated with PGPC. Intracellular levels of ferrous iron, lipid peroxidation, superoxide anions (O), and glutathione were detected, and expression of fatty acid binding protein-3 (FABP3), glutathione peroxidase 4 (GPX4), and CD36 were measured. Additionally, the mitochondrial membrane potential (MMP) was determined. Aortas from C57BL6 mice were isolated for vasodilation testing. Results showed that PGPC increased ferrous iron levels, the production of lipid peroxidation and O, and FABP3 expression. However, PGPC inhibited the expression of GPX4 and glutathione production and destroyed normal MMP. These effects were also blocked by ferrostatin-1, an inhibitor of ferroptosis. FABP3 silencing significantly reversed the effect of PGPC. Furthermore, PGPC stimulated CD36 expression. Conversely, CD36 silencing reversed the effects of PGPC, including PGPC-induced FABP3 expression. Importantly, E06, a direct inhibitor of the oxidized 1-palmitoyl-2-arachidonoyl-phosphatidylcholine IgM natural antibody, inhibited the effects of PGPC. Finally, PGPC impaired endothelium-dependent vasodilation, ferrostatin-1 or FABP3 inhibitors inhibited this impairment. Our data demonstrate that PGPC impairs endothelial function by inducing endothelial cell ferroptosis through the CD36 receptor to increase FABP3 expression. Our findings provide new insights into the mechanisms of atherosclerosis and a therapeutic target for atherosclerosis.
Topics: Animals; Mice; Humans; Phospholipids; Phosphorylcholine; Phospholipid Ethers; Ferroptosis; Mice, Inbred C57BL; Atherosclerosis; Human Umbilical Vein Endothelial Cells; Endothelium; Glutathione; Iron; Fatty Acid Binding Protein 3; Cyclohexylamines; Phenylenediamines
PubMed: 38218337
DOI: 10.1016/j.jlr.2024.100499 -
The Journal of Biological Chemistry May 2023N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff-base conjugate formed through the reversible reaction of retinal (Vitamin A-aldehyde) and...
N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff-base conjugate formed through the reversible reaction of retinal (Vitamin A-aldehyde) and phosphatidylethanolamine, plays a crucial role in the visual cycle and visual pigment photoregeneration. However, N-Ret-PE can react with another molecule of retinal to form toxic di-retinoids if not removed from photoreceptors through its transport across photoreceptor membranes by the ATP-binding-cassette transporter ABCA4. Loss-of-function mutations in ABCA4 are known to cause Stargardt disease (STGD1), an inherited retinal degenerative disease associated with the accumulation of fluorescent di-retinoids and severe loss in vision. A larger assessment of retinal-phospholipid Schiff-base conjugates in photoreceptors is needed, along with further investigation of ABCA4 residues important for N-Ret-PE binding. In this study we show that N-Ret-PE formation is dependent on pH and phospholipid content. When retinal is added to liposomes or photoreceptor membranes, 40 to 60% is converted to N-Ret-PE at physiological pH. Phosphatidylserine and taurine also react with retinal to form N-retinylidene-phosphatidylserine and N-retinylidene-taurine, respectively, but at significantly lower levels. N-retinylidene-phosphatidylserine is not a substrate for ABCA4 and reacts poorly with retinal to form di-retinoids. Additionally, amino acid residues within the binding pocket of ABCA4 that contribute to its interaction with N-Ret-PE were identified and characterized using site-directed mutagenesis together with functional and binding assays. Substitution of arginine residues and hydrophobic residues with alanine or residues implicated in STGD1 significantly reduced or eliminated substrate-activated ATPase activity and substrate binding. Collectively, this study provides important insight into conditions which affect retinal-phospholipid Schiff-base formation and mechanisms underlying the pathogenesis of STGD1.
Topics: Humans; ATP-Binding Cassette Transporters; Phosphatidylserines; Phospholipids; Retinoids; Stargardt Disease
PubMed: 36931393
DOI: 10.1016/j.jbc.2023.104614 -
Nature Communications Aug 2023Chloride channels (CLCs) transport anion across membrane to regulate ion homeostasis and acidification of intracellular organelles, and are divided into anion channels...
Chloride channels (CLCs) transport anion across membrane to regulate ion homeostasis and acidification of intracellular organelles, and are divided into anion channels and anion/proton antiporters. Arabidopsis thaliana CLCa (AtCLCa) transporter localizes to the tonoplast which imports NO and to a less extent Cl from cytoplasm. The activity of AtCLCa and many other CLCs is regulated by nucleotides and phospholipids, however, the molecular mechanism remains unclear. Here we determine the cryo-EM structures of AtCLCa bound with NO and Cl, respectively. Both structures are captured in ATP and PI(4,5)P bound conformation. Structural and electrophysiological analyses reveal a previously unidentified N-terminal β-hairpin that is stabilized by ATP binding to block the anion transport pathway, thereby inhibiting the AtCLCa activity. While AMP loses the inhibition capacity due to lack of the β/γ- phosphates required for β-hairpin stabilization. This well explains how AtCLCa senses the ATP/AMP status to regulate the physiological nitrogen-carbon balance. Our data further show that PI(4,5)P or PI(3,5)P binds to the AtCLCa dimer interface and occupies the proton-exit pathway, which may help to understand the inhibition of AtCLCa by phospholipids to facilitate guard cell vacuole acidification and stomatal closure. In a word, our work suggests the regulatory mechanism of AtCLCa by nucleotides and phospholipids under certain physiological scenarios and provides new insights for future study of CLCs.
Topics: Arabidopsis; Nucleotides; Protons; Nitrates; Phospholipids; Arabidopsis Proteins; Anions; Adenosine Triphosphate; Chloride Channels
PubMed: 37573431
DOI: 10.1038/s41467-023-40624-z -
International Journal of Molecular... Mar 2021The interactions at the atomic level between small molecules and the main components of cellular plasma membranes are crucial for elucidating the mechanisms allowing for...
The interactions at the atomic level between small molecules and the main components of cellular plasma membranes are crucial for elucidating the mechanisms allowing for the entrance of such small species inside the cell. We have performed molecular dynamics and metadynamics simulations of tryptophan, serotonin, and melatonin at the interface of zwitterionic phospholipid bilayers. In this work, we will review recent computer simulation developments and report microscopic properties, such as the area per lipid and thickness of the membranes, atomic radial distribution functions, angular orientations, and free energy landscapes of small molecule binding to the membrane. Cholesterol affects the behaviour of the small molecules, which are mainly buried in the interfacial regions. We have observed a competition between the binding of small molecules to phospholipids and cholesterol through lipidic hydrogen-bonds. Free energy barriers that are associated to translational and orientational changes of melatonin have been found to be between 10-20 kJ/mol for distances of 1 nm between melatonin and the center of the membrane. Corresponding barriers for tryptophan and serotonin that are obtained from reversible work methods are of the order of 10 kJ/mol and reveal strong hydrogen bonding between such species and specific phospholipid sites. The diffusion of tryptophan and melatonin is of the order of 10-7 cm2/s for the cholesterol-free and cholesterol-rich setups.
Topics: 1,2-Dipalmitoylphosphatidylcholine; Cholesterol; Dimyristoylphosphatidylcholine; Hydrogen Bonding; Lipid Bilayers; Melatonin; Molecular Dynamics Simulation; Serotonin; Solutions; Static Electricity; Thermodynamics; Tryptophan; Water
PubMed: 33799606
DOI: 10.3390/ijms22062842 -
Biochimica Et Biophysica Acta.... Oct 2020The plasma membrane phospholipid distribution of animal cells is markedly asymmetric. Phosphatidylserine (PS) and phosphatidylethanolamine (PE) are concentrated in the... (Review)
Review
The plasma membrane phospholipid distribution of animal cells is markedly asymmetric. Phosphatidylserine (PS) and phosphatidylethanolamine (PE) are concentrated in the inner leaflet, whereas phosphatidylcholine (PC) and sphingomyelin (SM) are concentrated in the outer leaflet. This non-equilibrium situation is maintained by lipid pumps (flippases or floppases), which utilize energy in the form of ATP to translocate lipids from one leaflet to the other. Scramblases, which are activated when physiologically required, transport lipids in both directions across the membrane and can abolish lipid asymmetry. Lipid asymmetry also causes imbalances in the areas occupied by lipid in the two membrane leaflets, contributing to membrane curvature. The asymmetry of PS across the plasma membrane plays a crucial signalling role in numerous physiological processes. Exposure of PS on the external surface of blood platelets stimulates blood coagulation. PS exposure by other cells during apoptosis provides an "eat me" signal to surrounding macrophages. Many peripheral and integral membrane proteins have polybasic PS-binding domains on their cytoplasmic surfaces which either provide a membrane anchor or affect activity. These domains can also determine trafficking within the cell and control regulation via an electrostatic switch mechanism, as well as potentially acting as "death sensors" when cytoplasmic PS is transferred to the extracellular leaflet during apoptosis. Apart from these physiological roles, external PS exposure by microorganisms, viruses and cancer cells allows them to mimic the immunosuppressive anti-inflammatory action of apoptotic cells and proliferate, thus providing a strong medical motivation for future research in the field of lipid asymmetry in membranes.
Topics: Animals; Cell Membrane; Humans; Phospholipids; Signal Transduction
PubMed: 32511979
DOI: 10.1016/j.bbamem.2020.183382 -
Cellular Microbiology Jul 2020Numerous bacterial toxins exert their activity by inactivating or modulating a specific intracellular host target. For this purpose, these toxins have developed... (Review)
Review
Numerous bacterial toxins exert their activity by inactivating or modulating a specific intracellular host target. For this purpose, these toxins have developed efficient strategies to overcome the different host cell defences including specific binding to cell surface, internalisation, passage through the endosome or plasma membrane, exploiting intracellular trafficking and addressing to intracellular targets. Several intracellularly active toxins deliver an active domain into the cytosol that interacts with a target localised to the inner face of the plasma membrane. Thus, the large clostridial glucosylating toxins (LCGTs) target Rho/Ras-GTPases, certain virulence factors of Gram negative bacteria, Rho-GTPases, while Pasteurella multocida toxin (PMT) targets trimeric G-proteins. Others such as botulinum neurotoxins and tetanus neurotoxin have their substrate on synaptic vesicle membrane. LCGTs, PMT, and certain virulence factors from Vibrio sp. show a particular structure constituted of a four-helix bundle membrane (4HBM) protruding from the catalytic site that specifically binds to the membrane phospholipids and then trap the catalytic domain at the proximity of the membrane anchored substrate. Structural and functional analysis indicate that the 4HBM tip of the Clostridium sordellii lethal toxin (TcsL) from the LCGT family contain two loops forming a cavity that mediates the binding to phospholipids and more specifically to phosphatidylserine.
Topics: Animals; Bacterial Proteins; Bacterial Toxins; Botulinum Toxins; Catalytic Domain; Cell Membrane; Cytoplasm; Humans; Legionella pneumophila; Metalloendopeptidases; Neurotoxins; Phosphatidic Acids; Phosphatidylserines; Tetanus Toxin; Virulence Factors; rho GTP-Binding Proteins
PubMed: 32353188
DOI: 10.1111/cmi.13213