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Lipidomic Insight into Membrane Remodeling in Aging and Neurodegenerative Diseases
Published in Abhai Kumar, Debasis Bagchi, Antioxidants and Functional Foods for Neurodegenerative Disorders, 2021
The combination of proteins linked to lipids moieties, embedded in the plasma membrane, create highly organized multimolecular networks organized in multidimensional lipids rafts rich in sphingolipids and cholesterol [24]. Lipid rafts also comprise phosphatidylcholine with saturated acyl chains in their structures, as well as smaller amounts of other phospholipids. Polyunsaturated fatty acids (PUFAs) play a major role in forming tightly packed lipid rafts, aggregates of cholesterol, and sphingolipids floating in fluid phospholipids of the bilayer [25]. The palmitate (C16:0) is a predominant saturated fatty acid, whereas unsaturated fatty acids are less abundant in raft domains [26].
Molecular and Cellular Pathogenesis of Systemic Lupus Erythematosus
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
George C. Tsokos, Yuang-Taung Juang, Christos G. Tsokos, Madhusoodana P. Nambiar
The T cell receptor ζ chain associated with the detergent-insoluble fraction is distributed between cytoskeleton as well as lipid-rich membrane microdomains, composed primarily of sphingolipids and cholesterol, and an enriched subset of proteins that float laterally as ‘rafts’ within the plasma membrane.38 Lipid rafts are preformed functional modules that serve as platforms for signal transduction and membrane trafficking. Recent data indicate that lipid rafts are crucial for effecting T cell receptor signal transduction.39,40 T cell receptor engagement leads to translocation and concentration of tyrosine phosphorylated T cell receptor ζ chain and downstream signal transduction molecules within lipid rafts.41 Conversely, perturbation of the structural integrity of lipid rafts inhibits T cell receptor-induced protein tyrosine phosphorylation and calcium flux.40,42
Brucella: A Foodborne Pathogen
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
For cellular entry, smooth Brucella that have not been opsonized by antibodies use the cytoskeleton of the host cell and interact with cholesterol-rich microdomains (lipid rafts) within the plasma membrane that facilitate contact with the host cell and mediate internalization. Lipid rafts contain glycosphingolipids, cholesterol, and glycosyl-phosphatidylinositol-anchored proteins37 and facilitate membrane-associated sorting events such as the formation of multi-subunit membrane complexes and signaling across membranes and membrane fusion. Besides the plasma membrane, lipid rafts are also found in intracellular organelles and vesicles. The Brucella LPS O–polysaccharide appears to be a key molecule for interaction with lipid rafts on host cells, but also prevents complement-mediated bacterial lysis and prevents host cell apoptosis.39 Opsonization of smooth strains of Brucella increases entry 10-fold and occurs through IgG (Fc) and complement (C3b and 4b) receptors on the surface of phagocytes, which diverts smooth bacteria from lipid rafts and targets entry to the phagolysosomal compartment. Receptor-mediated phagocytosis leads to greater killing of internalized Brucella by monocytes. In contrast to smooth Brucella, rough strains of Brucella cannot sustain interactions with lipid rafts and are phagocytosed by either toll-like receptor 4 or mannose receptor recognition of the LPS-deficient bacterial surface leading to rapid targeting to the phagolysosomal compartment, where they are generally unable to replicate.
Impact of quorum sensing signaling molecules in gram-negative bacteria on host cells: current understanding and future perspectives
Published in Gut Microbes, 2022
Yingping Xiao, Huicong Zou, Jingjing Li, Tongxing Song, Wentao Lv, Wen Wang, Zhenyu Wang, Shiyu Tao
The lipid raft is a micro-domain on the plasma membrane that is rich in cholesterol and sphingomyelin. The lipid raft is like a platform for protein parking that is closely related to membrane signal transduction and protein sorting. Lipid rafts may initially form in the endoplasmic reticulum, and some lipid rafts can be cross-linked with submembrane cytoskeletal proteins to varying degrees after being transported to the cell membrane.86–89 Presently, there is no consensus on whether lipid rafts mediate the harmful biological functions of AHLs on the host. Because AHL is a kind of lipid-soluble small molecule, it has been reported that cholesterol on the cell membrane is a potential receptor for AHL, and AHL can be transported into the cell through lipid rafts on the cell membrane to perform specific biological functions. The destroyer of lipid rafts, MβCD, disrupts the structure of lipid rafts by removing cholesterol from the cell membrane. It can effectively inhibit the increase in the permeability of Caco-2 cells induced by AHL.90 However, another report indicates that AHL can enter the host cell through a passive transport pathway and has little interaction with the cell membrane.42 The reason for this discrepancy in findings may be due to the different cell types that were used, but the relationship between lipid rafts and AHLs still needs further research (Figure 2).
The involvement of liquid crystals in multichannel implanted neurostimulators, hearing and ENT infections, and cancer
Published in Acta Oto-Laryngologica, 2019
Chouard Claude-Henri, Christiane Binot, Jean-François Sadoc
We previously stressed the essential role of nanodomains known as lipid rafts in neurodegenerative, infectious, and oncologic processes [17,18]. This concept of lipid rafts has broadened in recent decades. Tetraspanin-enriched microdomains are involved in ENT pathophysiology. Tetraspanins are transmembrane glycoproteins able to associate with one another and with other proteins. Six tetraspanins (Tspan 5, 10, 14, 15, 17, 33) of the Tspan 8 subfamily interact directly with ADAM10 metalloprotease [70]. This is anchored in the plasma membrane and induces proteolytic cleavage of the ectodomain of various surface molecules, and turns out to play an essential role in Notch pathway signaling activation, which is up-regulated by Tspan5 and 4 and down-regulated by Tspan15. Tspan15 is a down-regulator acting upstream of gamma secretase. Single-molecule studies show that membrane zones are reorganized during this regulation process, notably modifying the dynamics of ADAM10 and its interactions with tetraspanins.
Advances and challenges in understanding the role of the lipid raft proteome in human health
Published in Expert Review of Proteomics, 2018
Ahmed Mohamed, Harley Robinson, Pablo Joaquin Erramouspe, Michelle M Hill
Membrane microdomains are biophysical manifestations of lipid phase separation which occurs in cellular membranes containing a mixture of lipids.Although ‘lipid raft’ has been used to denote the liquid-ordered (less fluid) phase characterized by enriched cholesterol and sphingolipids at the plasma membrane, intracellular rafts have been well characterized as mediating lipid trafficking and inter-organellar signaling.Isolation of pure lipid rafts for proteomics remains a significant technical challenge. Additional strategies should be incorporated in the experimental design, such as comparative proteomics and/or incorporation of subcellular fractionation.Lipid rafts are implicated in numerous diseases and health conditions, with varying levels of evidence. Further research is needed to clarify the role of lipids and lipid raft proteins in pathology, to enable the development of prevention and treatment strategies.