Search results for "Lipid raft"

Differential Effect of Plant Lipids on Membrane Organization

2015

SPE IPM; International audience; The high diversity of the plant lipid mixture raises the question of their respective involvement in the definition of membrane organization. This is particularly the case for plant plasma membrane, which is enriched in specific lipids, such as free and conjugated forms of phytosterols and typical phytosphingolipids, such as glycosylinositolphosphoceramides. This question was here addressed extensively by characterizing the order level of membrane from vesicles prepared using various plant lipid mixtures and labeled with an environment-sensitive probe. Fluorescence spectroscopy experiments showed that among major phytosterols, campesterol exhibits a stronger…

Cholesterol Hydroxylating Cytochrome P450 46A1: From Mechanisms of Action to Clinical Applications

2021

Cholesterol, an essential component of the brain, and its local metabolism are involved in many neurodegenerative diseases. The blood-brain barrier is impermeable to cholesterol; hence, cholesterol homeostasis in the central nervous system represents a balance betweenin situbiosynthesis and elimination. Cytochrome P450 46A1 (CYP46A1), a central nervous system-specific enzyme, converts cholesterol to 24-hydroxycholesterol, which can freely cross the blood-brain barrier and be degraded in the liver. By the dual action of initiating cholesterol efflux and activating the cholesterol synthesis pathway, CYP46A1 is the key enzyme that ensures brain cholesterol turnover. In humans and mouse models,…

Cholesterol trafficking and raft-like membrane domain composition mediate scavenger receptor class B type 1-dependent lipid sensing in intestinal epi…

2018

IF 5.547; International audience; Scavenger receptor Class B type 1 (SR-B1) is a lipid transporter and sensor. In intestinal epithelial cells, SR-B1-dependent lipid sensing is associated with SR-B1 recruitment in raft-like/ detergent-resistant membrane domains and interaction of its C-terminal transmembrane domain with plasma membrane cholesterol. To clarify the initiating events occurring during lipid sensing by SR-B1, we analyzed cholesterol trafficking and raft-like domain composition in intestinal epithelial cells expressing wild-type SR-B1 or the mutated form SR-B1-Q445A, defective in membrane cholesterol binding and signal initiation. These features of SR-B1 were found to influence bo…

Exploration of Fas S-Nitrosylation by the Biotin Switch Assay

2017

International audience; S-nitrosylation is the covalent attachment of nitric oxide radical to the thiol side chain of cysteine. The death receptor Fas/CD95 can be S-nitrosylated in cancer cell lines by NO donors or iNOS activation. This posttranslational modification (PTM) induces Fas aggregation into lipid rafts and enhances FasL-mediated signaling and apoptosis. In this report, we describe the detection of Fas S-nitrosylation by the most commonly used method, the biotin switch assay (BSA) technique, that allows the detection of this very labile covalent modification in cells or tissues. Briefly, this technique relies on the ability of ascorbate to reduce the covalent bond between the NO r…

2018

Defining functional domains and amino acid residues in G protein coupled receptors (GPCRs) represent an important way to improve rational drug design for this major class of drug targets. The cannabinoid type 1 (CB1) receptor is one of the most abundant GPCRs in the central nervous system and is involved in many physiological and pathophysiological processes. Interestingly, cannabinoid type 1 receptor with a phenylalanine 238 to leucine mutation (CB1F238L) has been already linked to a number of both in vitro and in vivo alterations. While CB1F238L causes significantly reduced presynaptic neurotransmitter release at the cellular level, behaviorally this mutation induces increased risk taking…

Microvesicles released from Giardia intestinalis disturb host-pathogen response in vitro

2017

Giardia intestinalis (G.I), is an anaerobic protozoan and the aetiological agent of giardiasis, a diarrhoea present worldwide and associated with poverty. G.I has a simple life cycle alternating between cyst and trophozoite. Cysts are transmitted orally to the stomach and transform to trophozoites in the intestine by a multifactorial process. Recently, microvesicles (MVs) have been found to be released from a wide range of eukaryotic cells. We have observed a release of MVs during the life cycle of G.I., identifying MVs from active trophozoites and from trophozoites differentiating to the cyst form. The aim of the current work was to investigate the role of MVs from G.I in the pathogenesis …

Polysialic acid chains exhibit enhanced affinity for ordered regions of membranes.

2018

Polysialic acid (polySia) forms linear chains which are usually attached to the external surface of the plasma membrane mainly through the Neural Cell Adhesion Molecule (NCAM) protein. It is exposed on neural cells, several types of cancer cells, dendritic cells, and egg and sperm cells. There are several lipid raft-related phenomena in which polySia is involved; however the mechanisms of polySia action as well as determinants of its localization in lipid raft microdomains are still unknown, although the majority of NCAM molecules in the liquid-ordered raft membrane fractions of neural cells appear to be polysialylated. Here we investigate the affinity of polySia (both soluble and NCAM-depe…

Amyloid β-peptide insertion in liposomes containing GM1-cholesterol domains.

2015

Neuronal membrane damage is related to the early impairments appearing in Alzheimer's disease due to the interaction of the amyloid β-peptide (Aβ) with the phospholipid bilayer. In particular, the ganglioside GM1, present with cholesterol in lipid rafts, seems to be able to initiate Aβ aggregation on membrane. We studied the thermodynamic and structural effects of the presence of GM1 on the interaction between Aβ and liposomes, a good membrane model system. Isothermal Titration Calorimetry highlighted the importance of the presence of GM1 in recruiting monomeric Aβ toward the lipid bilayer. Light and Small Angle X-ray Scattering revealed a different pattern for GM1 containing liposomes, bot…

Evidence-Based Clinical Use of Nanoscale Extracellular Vesicles in Nanomedicine

2016

collaboration au projet H2020 European Cooperation in Science and Technology (COST) program European Network on Microvesicles and Exosomes in Health and Disease (ME-HAD); International audience; Recent research has demonstrated that all body fluids assessed contain substantial amounts of vesicles that range in size from 30 to 1000 nm and that are surrounded by phospholipid membranes containing different membrane microdomains such as lipid rafts and caveolae. The most prominent representatives of these so-called extracellular vesicles (EVs) are nanosized exosomes (70-150 nm), which are derivatives of the endosomal system, and microvesicles (100-1000 nm), which are produced by outward budding…

Linoleic acid: Is this the key that unlocks the quantum brain? Insights linking broken symmetries in molecular biology, mood disorders and personalis…

2017

Abstract In this paper we present a mechanistic model that integrates subneuronal structures, namely ion channels, membrane fatty acids, lipid rafts, G proteins and the cytoskeleton in a dynamic system that is finely tuned in a healthy brain. We also argue that subtle changes in the composition of the membrane’s fatty acids may lead to down-stream effects causing dysregulation of the membrane, cytoskeleton and their interface. Such exquisite sensitivity to minor changes is known to occur in physical systems undergoing phase transitions, the simplest and most studied of them is the so-called Ising model, which exhibits a phase transition at a finite temperature between an ordered and disorde…