Lipid Rafts Research Articles

High-frequency MHz-order vibration enables cell membrane remodeling and lipid microdomain manipulation

We elucidate the mechanism underpinning a recently discovered phenomenon in which cells respond to MHz-order mechanostimuli. Deformations induced along the plasma membrane under these external mechanical cues are observed to decrease the membrane tension, which, in turn, drives transient and reversible remodeling of its lipid structure. In particular, the increase and consequent coalescence of ordered lipid microdomains leads to closer proximity to mechanosensitive ion channels—Piezo1, in particular—that, due to crowding, results in their activation to mobilize influx of calcium (Ca2+) ions into the cell. It is the modulation of this second messenger that is responsible for the downstream signaling and cell fates that ensue. In addition, we show that such spatiotemporal control over the membrane microdomains in cells—without necessitating biochemical factors—facilitates aggregation and association of intrinsically disordered tau proteins in neuroblastoma cells, and their transformation to pathological conditions implicated in neurodegenerative diseases, thereby paving the way for the development of therapeutic intervention strategies.

Histone MARylation regulates lipid metabolism in colorectal cancer by promoting IGFBP1 methylation

In the global health community, colorectal cancer (CRC) is a major concern, with a high rate of incidence. Mono-ADP-ribosylation (MARylation) is a type of epigenetics and recognized as one of the causes of CRC development and progression. Although the modification level and target proteins in CRC remain unclear, it has been found that MARylation of arginine-117 of histone 3 (H3R117) promotes the proliferation, upregulates methylation of tumor suppressor gene, and is tightly associated with the metabolic processes in LoVo cells. Lipid metabolism disorder is involved in the development of CRC at the early stage. Our study revealed that MARylation of H3R117 of the LoVo cells modulated lipid metabolism, increased cholesterol synthesis, promoted lipid raft (LR) protein IGF-1R distribution, and inhibited cell apoptosis through IGFBP1. In addition, bioinformatics analyses revealed that IGFBP1 promoter was hypermethylated in CRC when compared to that in normal tissues. Moreover, H3R117 MARylation upregulated the methylation of IGFBP1 promoter through histone H3 citrullination (H3cit) by increasing the H3K9me2, heterochromatin protein1 (HP1), and DNA methyltransferase 1 (DNMT1) enrichment of IGFBP1 promoter. Accordingly, IGFBP1 may function as a tumor suppressor gene, while H3R117 MARylation may promote CRC development. Our study findings enrich the available data on epigenetics of CRC and provide a new idea and experimental basis for H3R117 MARylation as a target in CRC treatment.

Integrating molecular and cellular components of endothelial shear stress mechanotransduction.

The lining of blood vessels is constantly exposed to mechanical forces exerted by blood flow against the endothelium. Endothelial cells detect these tangential forces (i.e., shear stress), initiating a host of intracellular signaling cascades that regulate vascular physiology. Thus, vascular health is tethered to the endothelial cells' capacity to transduce shear stress. Indeed, the mechanotransduction of shear stress underlies a variety of cardiovascular benefits, including some of those associated with increased physical activity. However, endothelial mechanotransduction is impaired in aging and disease states such as obesity and type 2 diabetes, precipitating the development of vascular disease. Understanding endothelial mechanotransduction of shear stress, and the molecular and cellular mechanisms by which this process becomes defective, is critical for the identification and development of novel therapeutic targets against cardiovascular disease. In this review, we detail the primary mechanosensitive structures that have been implicated in detecting shear stress, including junctional proteins such as platelet endothelial cell adhesion molecule-1 (PECAM-1), the extracellular glycocalyx and its components, and ion channels such as piezo1. We delineate which molecules are truly mechanosensitive and which may simply be indispensable for the downstream transmission of force. Furthermore, we discuss how these mechanosensors interact with other cellular structures, such as the cytoskeleton and membrane lipid rafts, which are implicated in translating shear forces to biochemical signals. Based on findings to date, we also seek to integrate these cellular and molecular mechanisms with a view of deciphering endothelial mechanotransduction of shear stress, a tenet of vascular physiology.

Size-dependent composition and in-situ structure analysis of the milk fat globule membrane in buffalo milk

This study provides insights into the composition and in-situ structures of the milk fat globule membrane (MFGM) in buffalo milk with different fat globule sizes (0.55 μm and 8.04 μm). Small fat globules contained a higher amount of MFGM proteins and polar lipids, while the content of MFGM components (except for ADPH) was greater per unit membrane area in large fat globules. A total of 386 differentially expressed proteins were identified, with many of the most differentially expressed proteins being associated with human diseases, such as cancer and elderly diseases. The coverage of sphingomyelin and certain MFGM proteins (BTN and PAS 6/7) on large fat globules was higher, potentially linked to the presence of larger, irregular lipid rafts and patch-shaped glycocalyxes, respectively. These findings suggest that small fat globules are suitable for nutritional fortification of buffalo milk, while large fat globules are appropriate for the preparation of functional dairy-based ingredients.

Anti-inflammatory oligosaccharide licensed mesenchymal stem cells allow prolonged survival of septic rats via the promotion of glutathione synthesis

BackgroundMesenchymal stem cells (MSCs) possess the capability to mitigate multiorgan failure (MOF) and reduce mortality rates in sepsis. However, their survival is significantly limited due to oxidative stress responses triggered by excessive sepsis inflammation. Previous studies have demonstrated that the paracrine effect of MSCs can be enhanced by cytokine stimuli such as IL-1β, TNF-α, and IFN-γ, a process known as inflammatory licensing. This enhancement, however, may potentially lead to the apoptosis of MSCs. PurposeTo investigate the therapeutic effects of Fructus Lycii oligosaccharide (FLO)-nasal mucosa-derived ectodermal MSCs (EMSCs) on septic rats and the underlying mechanisms. Study design and methodsFLO was screened from 21 distinct saccharides derived from traditional Chinese medicine (TCM), utilizing macrophage lipid raft chromatography prepared by our laboratory as the primary screening method.. The comparison of EMSCs primed with/without FLO was assessed through RNA-seq. Cecal ligation and puncture (CLP) surgery was performed in the CLP, EMSCs, and FLO-EMSCs groups (n = 10). The NC group underwent cecal ligation without puncture. The therapeutic effects of EMSCs and FLO-EMSCs on septic rats were evaluated through multiple tests including RT-PCR, western blot, histochemical staining, etc. ResultsFLO promoted M2 polarization of macrophages and enhanced the paracrine effect of EMSCs, without inducing apoptosis. Furthermore, FLO promoted GSH synthesis in EMSCs, aiding in the removal of reactive oxygen species (ROS) within these cells. The FLO-treated EMSCs demonstrated enhanced protection against pyroptosis in macrophages, thereby preventing immune paralysis during sepsis. ConclusionThis study presents an innovative approach for enhancing the anti-inflammatory properties of MSCs using a TCM-derived oligosaccharide, thereby improving their therapeutic efficacy in sepsis models.

ACSL4-mediated lipid rafts prevent membrane rupture and inhibit immunogenic cell death in melanoma

Chemotherapy including platinum-based drugs are a possible strategy to enhance the immune response in advanced melanoma patients who are resistant to immune checkpoint blockade (ICB) therapy. However, the immune-boosting effects of these drugs are a subject of controversy, and their impact on the tumor microenvironment are poorly understood. In this study, we discovered that lipid peroxidation (LPO) promotes the formation of lipid rafts in the membrane, which mediated by Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4) impairs the sensitivity of melanoma cells to platinum-based drugs. This reduction primarily occurs through the inhibition of immunogenic ferroptosis and pyroptosis by reducing cell membrane pore formation. By disrupting ACSL4-mediaged lipid rafts via the removal of membrane cholesterol, we promoted immunogenic cell death, transformed the immunosuppressive environment, and improved the antitumor effectiveness of platinum-based drugs and immune response. This disruption also helped reverse the decrease in CD8+ T cells while maintaining their ability to secrete cytokines. Our results reveal that ACSL4-dependent LPO is a key regulator of lipid rafts formation and antitumor immunity, and that disrupting lipid rafts has the potential to enhance platinum-based drug-induced immunogenic ferroptosis and pyroptosis in melanoma. This novel strategy may augment the antitumor immunity of platinum-based therapy and further complement ICB therapy.

AIBP controls TLR4 inflammarafts and mitochondrial dysfunction in a mouse model of Alzheimer’s disease

Microglia-driven neuroinflammation plays an important role in the development of Alzheimer’s disease. Microglia activation is accompanied by the formation and chronic expression of TLR4 inflammarafts, defined as enlarged and cholesterol-rich lipid rafts serving as an assembly platform for TLR4 dimers and complexes of other inflammatory receptors. The secreted apoA-I binding protein (APOA1BP or AIBP) binds TLR4 and selectively targets cholesterol depletion machinery to TLR4 inflammaraft-expressing inflammatory, but not homeostatic microglia. Here we demonstrated that amyloid-beta (Aβ) induced formation of TLR4 inflammarafts in microglia in vitro and in the brain of APP/PS1 mice. Mitochondria in Apoa1bp−/− APP/PS1 microglia were hyperbranched and cupped, which was accompanied by increased reactive oxygen species and the dilated endoplasmic reticulum. The size and number of Aβ plaques and neuronal cell death were significantly increased, and the animal survival was decreased in Apoa1bp−/−APP/PS1 compared to APP/PS1 female mice. These results suggest that AIBP exerts control of TLR4 inflammarafts and mitochondrial dynamics in microglia and plays a protective role in Alzheimer’s disease associated oxidative stress and neurodegeneration.

Nonequilibrium cluster-cluster aggregation in the presence of anchoring sites.

Nonequilibrium cluster-cluster aggregation of particles diffusing in or at the cell membrane has been hypothesized to lead to domains of finite size in different biological contexts, such as lipid rafts, cell adhesion complexes, or postsynaptic domains in neurons. In this scenario, the desorption of particles balances a continuous flux to the membrane, imposing a cutoff on possible aggregate sizes and giving rise to a stationary size distribution. Here, we investigate the case of nonequilibrium cluster-cluster aggregation in two dimensions where diffusing particles and/or clusters remain fixed in space at specific anchoring sites, which should be particularly relevant for synapses but may also be present in other biological or physical systems. Using an effective mean-field description of the concentration field around anchored clusters, we derive an expression for their average size as a function of parameters such as the anchoring site density. We furthermore propose and solve appropriate rate equationsthat allow us to predict the size distributions of both diffusing and fixed clusters. We confirm our results with particle-based simulations and discuss potential implications for biological and physical systems.

Raft-like lipid mixtures in the highly coarse-grained Cooke membrane model.

Lipid rafts are nanoscopic assemblies of sphingolipids, cholesterol, and specific membrane proteins. They are believed to underlie the experimentally observed lateral heterogeneity of eukaryotic plasma membranes and implicated in many cellular processes, such as signaling and trafficking. Ternary model membranes consisting of saturated lipids, unsaturated lipids, and cholesterol are common proxies because they exhibit phase coexistence between a liquid-ordered (lo) and liquid-disordered (ld) phase and an associated critical point. However, plasma membranes are also asymmetric in terms of lipid type, lipid abundance, leaflet tension, and corresponding cholesterol distribution, suggesting that rafts cannot be examined separately from questions about elasticity, curvature torques, and internal mechanical stresses. Unfortunately, it is challenging to capture this wide range of physical phenomenology in a single model that can access sufficiently long length- and time scales. Here we extend the highly coarse-grained Cooke model for lipids, which has been extensively characterized on the curvature-elastic front, to also represent raft-like lo/ld mixing thermodynamics. In particular, we capture the shape and tie lines of a coexistence region that narrows upon cholesterol addition, terminates at a critical point, and has coexisting phases that reflect key differences in membrane order and lipid packing. We furthermore examine elasticity and lipid diffusion for both phase separated and pure systems and how they change upon the addition of cholesterol. We anticipate that this model will enable significant insight into lo/ld phase separation and the associated question of lipid rafts for membranes that have compositionally distinct leaflets that are likely under differential stress-like the plasma membrane.

Biochemical Pathways Delivering Distinct Glycosphingolipid Patterns in MDA-MB-231 and MCF-7 Breast Cancer Cells.

The complex structure of glycosphingolipids (GSLs) supports their important role in cell function as modulators of growth factor receptors and glutamine transporters in plasma membranes. The aberrant composition of clustered GSLs within signaling platforms, so-called lipid rafts, inevitably leads to tumorigenesis due to disturbed growth factor signal transduction and excessive uptake of glutamine and other molecules needed for increased energy and structural molecule cell supply. GSLs are also involved in plasma membrane processes such as cell adhesion, and their transition converts cells from epithelial to mesenchymal with features required for cell migration and metastasis. Glutamine activates the mechanistic target of rapamycin complex 1 (mTORC1), resulting in nucleotide synthesis and proliferation. In addition, glutamine contributes to the cancer stem cell GD2 ganglioside-positive phenotype in the triple-negative breast cancer cell line MDA-MB-231. Thieno[2,3-b]pyridine derivative possesses higher cytotoxicity against MDA-MB-231 than against MCF-7 cells and induces a shift to aerobic metabolism and a decrease in S(6)nLc4Cer GSL-positive cancer stem cells in the MDA-MB-231 cell line. In this review, we discuss findings in MDA-MB-231, MCF-7, and other breast cancer cell lines concerning their differences in growth factor receptors and recent knowledge of the main biochemical pathways delivering distinct glycosphingolipid patterns during tumorigenesis and therapy.

Effect of nystatin on invasion of <i>Serratia grimesii</i> and <i>Serratia proteamaculans</i> bacteria into epithelial cells

BACKGROUND: Bacteria use various endocytic pathways during entering non-phagocytic cells. The involvement of caveolae/lipid rafts in bacterial invasion has been demonstrated for many bacterial pathogens. However, for bacteria of the genus Serratia, the involvement of membrane microdomains in the process of bacterial internalization has been poorly studied. AIM: To evaluate the involvement of caveolae/lipid rafts in the invasion of S. grimesii and S. proteamaculans bacteria into non-phagocytic epithelial Caco-2 and M-HeLa cells using nystatin. MATERIALS AND METHODS: M-HeLa and Caco-2 epithelial cells were incubated with 50 μM nystatin for 1 hour at 37 ºC, after which they were infected with the bacteria S. grimesii strain 30063 and S. proteamaculans strain 94, the multiplicity of infection was 100 bacteria per cell. The number of intracellular bacteria was assessed using gentamicin protection assay. The level of caveolin-1 in cells was visualized using confocal microscopy and Western blotting. The expression of Toll-like receptors genes were measured by real-time RT-PCR. RESULTS: Treatment of epithelial cells with nystatin reduces the internalization of S. grimesii and S. proteamaculans into M-HeLa cells by 30% and does not affect penetration into Caco-2 cells. At the same time, nystatin does not affect the redistribution / the integrity impairment of lipid rafts and does not lead to the cytoskeleton reorganization of eukaryotic cells. The addition of nystatin increases the level of caveolin-1 in M-HeLa cells (caveolin-1 is not expressed in Caco-2), which leads to a change plasma membrane fluidity. Nystatin promotes the secretion of proinflammatory cytokines interleukin-6 and interleukin-8 in both cell lines. Infection of M-HeLa cells pretreated with nystatin with the studied bacteria leads to an increase in the expression of tlr2 and tlr4 genes, but does not exceed the level of their expression in control samples. Therefore, it is impossible to speak unambiguously about the participation of Toll-like receptors in the invasion of Serratia bacteria. CONCLUSIONS: The results obtained suggest that the interaction of bacteria with eukaryotic cells induces the expression of caveolin-1, which leads to a change plasma membrane components mobility. This may be due to the fact that β1-integrin is involved in the invasion of the studied bacteria, which should be stabilized at the plasma membrane upon binding of the ligand due to the formation of a cholesterol- and sphingolipid-rich membrane microenvironment.

MβCD inhibits SFTSV entry by disrupting lipid raft structure of the host cells

Severe fever with thrombocytopenia syndrome virus (SFTSV), recently named as Dabie bandavirus, belongs to the family Phenuiviridae of the order Bunyavirales, is a newly-identified bunyavirus with a case fatality rate of up to 30%, posing a serious threat to public health. Lipid rafts on plasm membranes are important for the entry of enveloped viruses; however, the role of lipid rafts in bunyavirus entry remains unclear. In this study, we found that methyl-beta-cyclodextrin (MβCD), a drug that disrupts cholesterol in lipid rafts of cell membranes, inhibits SFTSV infection. Additionally, there is a back-complementary effect of SFTSV infection upon the addition of cholesterol. Moreover, the concentration of SFTSV particles in lipid rafts during entry directly indicated the role of lipid rafts as a gateway, whereas MβCD could inhibit SFTSV entry by affecting the structure of lipid rafts. In an in vivo study, MβCD also reduced the susceptibility of mice to SFTSV infection. Our results suggest that SFTSV can interact with Talin1 proteins on lipid rafts to enter host cells by endocytosis of lipid rafts and reveal the potential therapeutic value of MβCD for SFTSV infection.

ASMase is Essential for the Immune Response to Partial-Tumor Radiation Exposure.

Tumor response to radiation is thought to depend on the direct killing of tumor cells. Our laboratory has called this into question. Firstly, we showed that the biology of the host, specifically the endothelial expression of acid sphingomyelinase (ASMase), was critical in determining tumor radiocurability. Secondly, we have shown that the immune system can enhance radiation response by allowing a complete tumor control in hemi-irradiated tumors. In this paper, we focus on the integration of these two findings. We used Lewis Lung Carcinoma (LLC) cells, injected in the flank of either: (i) ASMase knockout or (ii) WT of matched background (sv129xBl/6) or (iii) C57Bl/6 mice. Radiation therapy (RT) was delivered to 50% or 100% of the LLC tumor volume. Tumor response, immune infiltration (CD8+ T cells), ICAM-1, and STING activation were measured. Radiotherapy was also combined with methyl-cyclodextrin, to inhibit the ASMase-mediated formation of ceramide-enriched lipid rafts. We recapitulated our previous finding, namely that tumor hemi-irradiation was sufficient for tumor control in the LLC/C57Bl/6 model. However, in ASMase KO mice hemi-irradiation was ineffective. Likewise, pharmacological inhibition of ASMase significantly reduced the tumor response to hemi-irradiation. Further, we demonstrated elevated ICAM-1 expression, increased levels of CD8+ T cells, ICAM-1, and STING activation in tumors growing in C57Bl/6 mice, as well as the ASMase WT strain. However, no such changes were seen in tumors growing in ASMase KO mice. ASMase and ceramide generation are necessary to mediate a radiation-induced anti-tumor immune response via STING activation.

Exploring HIV-1 Maturation: A New Frontier in Antiviral Development.

HIV-1 virion maturation is an essential step in the viral replication cycle to produce infectious virus particles. Gag and Gag-Pol polyproteins are assembled at the plasma membrane of the virus-producer cells and bud from it to the extracellular compartment. The newly released progeny virions are initially immature and noninfectious. However, once the Gag polyprotein is cleaved by the viral protease in progeny virions, the mature capsid proteins assemble to form the fullerene core. This core, harboring two copies of viral genomic RNA, transforms the virion morphology into infectious virus particles. This morphological transformation is referred to as maturation. Virion maturation influences the distribution of the Env glycoprotein on the virion surface and induces conformational changes necessary for the subsequent interaction with the CD4 receptor. Several host factors, including proteins like cyclophilin A, metabolites such as IP6, and lipid rafts containing sphingomyelins, have been demonstrated to have an influence on virion maturation. This review article delves into the processes of virus maturation and Env glycoprotein recruitment, with an emphasis on the role of host cell factors and environmental conditions. Additionally, we discuss microscopic technologies for assessing virion maturation and the development of current antivirals specifically targeting this critical step in viral replication, offering long-acting therapeutic options.

Thrombomodulin (p.Cys537Stop) is released from cells by an unusual membrane insertion/leakage mechanism

AbstractExpression of the thrombomodulin (TM) variant c.1611C>A (p.Cys537Stop) leads to the synthesis of a protein with no cytoplasmic tail and a transmembrane domain shortened by 3 amino acids (TM536). However, little is known regarding the release mechanism and properties of TM536. Using umbilical vein endothelial cells and peripheral blood-derived endothelial colony-forming cells from a heterozygous carrier of the TM536 variant as well as overexpression cell models, we demonstrated that TM536 is released from cells by an unusual mechanism. First, TM536 is inserted into the endoplasmic reticulum (ER) membrane, then, because of the low hydrophobicity of its intramembrane domain, it escapes from it and follows the conventional secretory pathway to be released into the extracellular compartment without the involvement of proteolysis. This particular secretion mechanism yields a soluble TM536, which is poorly modified by chondroitin sulfate glycosaminoglycan compared with conventionally secreted soluble forms of TM, and therefore has a suboptimal capacity to mediate thrombin-dependent activation of protein C (PC). We also showed that TM536 cellular trafficking was altered, with retention in the early secretory pathway and increased sensitivity to ER-associated degradation. As expected, activation of ER-associated degradation increased TM536 degradation and reduced its release. The expression of TM536 at the cell surface was low, and its distribution in lipid raft-like membrane microdomains was altered, resulting in low thrombin-dependent PC activation on the cell surface.

Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts

Aquaporin-0 (AQP0) tetramers form square arrays in lens membranes through a yet unknown mechanism, but lens membranes are enriched in sphingomyelin and cholesterol. Here, we determined electron crystallographic structures of AQP0 in sphingomyelin/cholesterol membranes and performed molecular dynamics (MD) simulations to establish that the observed cholesterol positions represent those seen around an isolated AQP0 tetramer and that the AQP0 tetramer largely defines the location and orientation of most of its associated cholesterol molecules. At a high concentration, cholesterol increases the hydrophobic thickness of the annular lipid shell around AQP0 tetramers, which may thus cluster to mitigate the resulting hydrophobic mismatch. Moreover, neighboring AQP0 tetramers sandwich a cholesterol deep in the center of the membrane. MD simulations show that the association of two AQP0 tetramers is necessary to maintain the deep cholesterol in its position and that the deep cholesterol increases the force required to laterally detach two AQP0 tetramers, not only due to protein–protein contacts but also due to increased lipid–protein complementarity. Since each tetramer interacts with four such ‘glue’ cholesterols, avidity effects may stabilize larger arrays. The principles proposed to drive AQP0 array formation could also underlie protein clustering in lipid rafts.

Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts.

Aquaporin-0 (AQP0) tetramers form square arrays in lens membranes through a yet unknown mechanism, but lens membranes are enriched in sphingomyelin and cholesterol. Here, we determined electron crystallographic structures of AQP0 in sphingomyelin/cholesterol membranes and performed molecular dynamics (MD) simulations to establish that the observed cholesterol positions represent those seen around an isolated AQP0 tetramer and that the AQP0 tetramer largely defines the location and orientation of most of its associated cholesterol molecules. At a high concentration, cholesterol increases the hydrophobic thickness of the annular lipid shell around AQP0 tetramers, which may thus cluster to mitigate the resulting hydrophobic mismatch. Moreover, neighboring AQP0 tetramers sandwich a cholesterol deep in the center of the membrane. MD simulations show that the association of two AQP0 tetramers is necessary to maintain the deep cholesterol in its position and that the deep cholesterol increases the force required to laterally detach two AQP0 tetramers, not only due to protein-protein contacts but also due to increased lipid-protein complementarity. Since each tetramer interacts with four such 'glue' cholesterols, avidity effects may stabilize larger arrays. The principles proposed to drive AQP0 array formation could also underlie protein clustering in lipid rafts.

Evaluation Of Raftlin And 8-Iso Prostaglandin Levels On The Clinical Severity Of Cases With Covid-19 In Turkey : A Cross-Sectional Study

COVID-19 is an infectious respiratory disease caused by the severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2). Raftlin is a large lipid raft protein found in cell membranes and plays a crucial role in inducing autoimmune and vascular inflammatory responses. Although there have been few studies on 8-iso-prostaglandin F2α (8-iso-PGF2α) as a marker of oxidative stress in COVID-19, the levels of raftlin in the disease have not been previously investigated. The objective of our study was to evaluate the levels of Raftlin and 8-iso-prostaglandin F2α (8-iso-PGF2α) in COVID patients. We analyzed clinical findings from three groups: healthy controls, patients with a mild course of COVID, and patients with a severe course of COVID. We measured the levels of Raftlin and 8-iso-PGF2α in serum samples using ELISA. Our results showed that the levels of Raftlin and 8-iso-PGF2α were higher in patients with severe COVID compared to the control and mild course groups. Furthermore, a significant positive correlation was found between Raftlin and 8-iso-PGF2α in the severe COVID group. Raftlin was identified as a potentially important biomarker in COVID-19 patients. This study is valuable as it is the first to investigate changes in Raftlin and 8-iso-PGF2α levels in COVID-19 disease.

Effects of the oxoaporphine alkaloid hernandonine on dengue virus. Evidence for its mechanisms of action

BackgroundDengue, caused by the dengue virus (Orthoflavivirus dengue, encompassing DENV types 1-4), is a member of the Flaviviridae family. The symptoms of dengue range from subclinical or mild manifestations to potentially fatal complications. The management of severe dengue is exceptionally challenging due to the absence of effective antiviral medications. In this context, natural products, whether in the form of pure compounds or standardized plant extracts, have emerged as a promising source for the development of novel antiviral therapeutics. Hernandonine, an oxoaporphine alkaloid found in Hernandia nymphaeifolia (C. Presl) Kubitzki. serves both as a metabolite and an inhibitor of human immunodeficiency virus type 1 (HIV-1) integrase. PurposeThis study investigated the ability of hernandonine to inhibit DENV infection and explored its potential mechanisms. Study designTo assess the in vitro anti-DENV activity, cells or induced pluripotent stem cell (iPSC)-derived cerebral organoids were exposed to hernandonine before or after infection with DENV. Along with hernandonine, the endocytosis modulators, genistein, wortmannin, Methyl-β-cyclodextrin (MβCD) and lovastatin, were used in the assays. MethodsThe DENV infectivity and virion production in cells or cerebral organoids treated with compounds were determined. Various methods, including cell and cerebral organoids imaging, protein and gene detection were conducted to explore their antiviral mechanisms. ResultsThe results revealed notable antiviral properties of hernandonine, particularly in inhibiting DENV during the early stages of infection. Mechanistic analysis demonstrated that, akin to genistein, wortmannin, methyl-β-cyclodextrin (MβCD), and lovastatin, hernandonine exerted an influence on cholesterol-rich lipid rafts. It also restrained the pseudopodial movement ability of cells, potentially through the downregulation of cytoskeleton and endocytosis regulatory genes or protein expression. Moreover, hernandonine's virucidal activity was demonstrated. Hernandonine's inhibition of DENV infection was further validated in a disease-relevant iPSC-derived cerebral organoids model, a novel DENV-2 infection system worthy of further application. ConclusionThis study evidenced the potential of hernandonine as a novel candidate in the fight against DENV infection.

Cryo-EM structure of the SPFH-NfeD family protein complex QmcA-YbbJ

The SPFH (stomatin, prohibitin, flotillin, and HflK/C) protein family is universally present and encompasses the evolutionarily conserved SPFH domain. These proteins are predominantly localized in lipid raft and implicated in various biological processes. The NfeD (nodulation formation efficiency D) protein family is often encoded in tandem with SPFH proteins, suggesting a close functional relationship. Here, we elucidate the cryoelectron microscopy (cryo-EM) structure of the Escherichia coli QmcA-YbbJ complex belonging to the SPFH and NfeD families, respectively. Our findings reveal that the QmcA-YbbJ complex forms an intricate cage-like structure composed of 26 copies of QmcA-YbbJ heterodimers. The transmembrane helices of YbbJ act as adhesive elements bridging adjacent QmcA molecules, while the oligosaccharide-binding domain of YbbJ encapsulates the SPFH domain of QmcA. Our structural study significantly contributes to understanding the functional role of the NfeD protein family and sheds light on the interplay between SPFH and NfeD family proteins.