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1.
Development ; 151(9)2024 May 01.
Article in English | MEDLINE | ID: mdl-38713014

ABSTRACT

Lipid distribution in an organism is mediated by the interplay between lipoprotein particles, lipoprotein receptors and class B scavenger receptors of the CD36 family. CD36 is a multifunctional protein mediating lipid uptake, mobilization and signaling at the plasma membrane and inside of the cell. The CD36 protein family has 14 members in Drosophila melanogaster, which allows for the differentiated analysis of their functions. Here, we unravel a role for the so far uncharacterized scavenger receptor Bez in lipid export from Drosophila adipocytes. Bez shares the lipid binding residue with CD36 and is expressed at the plasma membrane of the embryonic, larval and adult fat body. Bez loss of function lowers the organismal availability of storage lipids and blocks the maturation of egg chambers in ovaries. We demonstrate that Bez interacts with the APOB homolog Lipophorin at the plasma membrane of adipocytes and trace the Bez-dependent transfer of an alkyne-labeled fatty acid from adipocytes to Lipophorin. Our study demonstrates how lipids are distributed by scavenger receptor-lipoprotein interplay and contribute to the metabolic control of development.


Subject(s)
CD36 Antigens , Drosophila Proteins , Drosophila melanogaster , Fat Body , Lipid Metabolism , Animals , Female , Adipocytes/metabolism , CD36 Antigens/metabolism , CD36 Antigens/genetics , Cell Membrane/metabolism , Drosophila melanogaster/metabolism , Drosophila Proteins/metabolism , Drosophila Proteins/genetics , Fat Body/metabolism , Lipoproteins/metabolism , Ovary/metabolism , Receptors, Scavenger/metabolism , Receptors, Scavenger/genetics
2.
J Immunol ; 212(11): 1782-1790, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38629901

ABSTRACT

Enterovirus 71 (EV71) is a significant causative agent of hand, foot, and mouth disease, with potential serious neurologic complications or fatal outcomes. The lack of effective treatments for EV71 infection is attributed to its elusive pathogenicity. Our study reveals that human plasmacytoid dendritic cells (pDCs), the main type I IFN-producing cells, selectively express scavenger receptor class B, member 2 (SCARB2) and P-selectin glycoprotein ligand 1 (PSGL-1), crucial cellular receptors for EV71. Some strains of EV71 can replicate within pDCs and stimulate IFN-α production. The activation of pDCs by EV71 is hindered by Abs to PSGL-1 and soluble PSGL-1, whereas Abs to SCARB2 and soluble SCARB2 have a less pronounced effect. Our data suggest that only strains binding to PSGL-1, more commonly found in severe cases, can replicate in pDCs and induce IFN-α secretion, highlighting the importance of PSGL-1 in these processes. Furthermore, IFN-α secretion by pDCs can be triggered by EV71 or UV-inactivated EV71 virions, indicating that productive infection is not necessary for pDC activation. These findings provide new insights into the interaction between EV71 and pDCs, suggesting that pDC activation could potentially mitigate the severity of EV71-related diseases.


Subject(s)
Dendritic Cells , Enterovirus A, Human , Interferon-alpha , Lysosomal Membrane Proteins , Membrane Glycoproteins , Dendritic Cells/immunology , Dendritic Cells/virology , Humans , Enterovirus A, Human/immunology , Enterovirus A, Human/physiology , Membrane Glycoproteins/metabolism , Lysosomal Membrane Proteins/metabolism , Lysosomal Membrane Proteins/immunology , Interferon-alpha/metabolism , Interferon-alpha/immunology , Receptors, Scavenger/metabolism , Enterovirus Infections/immunology , Enterovirus Infections/virology , Virus Replication
3.
Autoimmunity ; 57(1): 2201412, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38425093

ABSTRACT

OBJECTIVE: To explore the effect of CD5-like molecule (CD5L) on rheumatoid arthritis (RA) fibroblast-like synoviocytes (RA-FLS) and the relative molecular mechanism of CD5L in it. METHODS: Recombinant protein CD5L was used to stimulate the cultured RA-FLS cells. The inflammation-related cytokines were determined by real time-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The signal molecules and apoptosis-related molecules were detected by western blot assay (WB), and cell counting kit-8 (CCK-8) was used to detect the proliferation. RESULTS: CD5L can increase the production of IL-6, IL-8, and TNF-α and this effect can be inhibited by signal pathway inhibitor. At the same time, CD5L activated ERK1/2 MAPK signal, inhibitor treatment can weaken the intensity of phosphorylation. In addition, CD5L can enhance the proliferation ability of RA-FLS. CONCLUSION: CD5L induces the production of inflammatory cytokines in RA-FLS through the ERK1/2 MAPK pathway and increases cell survival.


Subject(s)
Arthritis, Rheumatoid , Synovial Membrane , Humans , Synovial Membrane/metabolism , MAP Kinase Signaling System , Arthritis, Rheumatoid/metabolism , Inflammation/metabolism , Cytokines/metabolism , Cells, Cultured , Fibroblasts/metabolism , Cell Proliferation , Apoptosis Regulatory Proteins , Receptors, Scavenger/metabolism
4.
Nat Commun ; 15(1): 1663, 2024 Feb 23.
Article in English | MEDLINE | ID: mdl-38396109

ABSTRACT

Targeted degradation of proteins has emerged as a powerful method for modulating protein homeostasis. Identification of suitable degraders is essential for achieving effective protein degradation. Here, we present a non-covalent degrader construction strategy, based on a modular supramolecular co-assembly system consisting of two self-assembling peptide ligands that bind cell membrane receptors and the protein of interest simultaneously, resulting in targeted protein degradation. The developed lysosome-targeting co-assemblies (LYTACAs) can induce lysosomal degradation of extracellular protein IL-17A and membrane protein PD-L1 in several scavenger receptor A-expressing cell lines. The IL-17A-degrading co-assembly has been applied in an imiquimod-induced psoriasis mouse model, where it decreases IL-17A levels in the skin lesion and alleviates psoriasis-like inflammation. Extending to asialoglycoprotein receptor-related protein degradation, LYTACAs have demonstrated the versatility and potential in streamlining degraders for extracellular and membrane proteins.


Subject(s)
Psoriasis , Skin , Animals , Mice , Skin/pathology , Interleukin-17/metabolism , Proteolysis , Psoriasis/metabolism , Receptors, Scavenger/metabolism , Membrane Proteins/metabolism , Lysosomes/metabolism , Disease Models, Animal
5.
PLoS Pathog ; 20(2): e1012022, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38359079

ABSTRACT

Enterovirus A71 (EV-A71) infection involves a variety of receptors. Among them, two transmembrane protein receptors have been investigated in detail and shown to be critical for infection: P-selectin glycoprotein ligand-1 (PSGL-1) in lymphocytes (Jurkat cells), and scavenger receptor class B member 2 (SCARB2) in rhabdomyosarcoma (RD) cells. PSGL-1 and SCARB2 have been reported to be expressed on the surface of Jurkat and RD cells, respectively. In the work reported here, we investigated the roles of PSGL-1 and SCARB2 in the process of EV-A71 entry. We first examined the expression of SCARB2 in Jurkat cells, and detected it within the cytoplasm, but not on the cell surface. Further, using PSGL-1 and SCARB2 knockout cells, we found that although both PSGL-1 and SCARB2 are essential for virus infection of Jurkat cells, virus attachment to these cells requires only PSGL-1. These results led us to evaluate the cell surface expression and the roles of SCARB2 in other EV-A71-susceptible cell lines. Surprisingly, in contrast to the results of previous studies, we found that SCARB2 is absent from the surface of RD cells and other susceptible cell lines we examined, and that although SCARB2 is essential for infection of these cells, it is dispensable for virus attachment. These results indicate that a receptor other than SCARB2 is responsible for virus attachment to the cell and probably for internalization of virions, not only in Jurkat cells but also in RD cells and other EV-A71-susceptible cells. SCARB2 is highly concentrated in lysosomes and late endosomes, where it is likely to trigger acid-dependent uncoating of virions, the critical final step of the entry process. Our results suggest that the essential interactions between EV-A71 and SCARB2 occur, not at the cell surface, but within the cell.


Subject(s)
Enterovirus A, Human , Enterovirus Infections , Enterovirus , Humans , Enterovirus/metabolism , Enterovirus A, Human/genetics , Enterovirus A, Human/metabolism , Cell Membrane/metabolism , Cell Line , Receptors, Scavenger/genetics , Receptors, Scavenger/metabolism , Lysosomal Membrane Proteins/genetics
6.
Cell Commun Signal ; 22(1): 97, 2024 02 02.
Article in English | MEDLINE | ID: mdl-38308264

ABSTRACT

BACKGROUND: Sepsis is a severe systemic inflammatory disorder manifested by a dysregulated immune response to infection and multi-organ failure. Numerous studies have shown that elevated ferritin levels exist as an essential feature during sepsis and are able to suggest patients' prognoses. At the same time, the specific mechanism of ferritin-induced inflammatory injury remains unclear. METHODS: Hyper-ferritin state during inflammation was performed by injecting ferritin into a mouse model and demonstrated that injection of ferritin could induce a systemic inflammatory response and increase neutrophil extracellular trap (NET) formation.Padi4-/-, Elane-/- and Cybb-/- mice were used for the NETs formation experiment. Western blot, immunofluorescence, ELISA, and flow cytometry examined the changes in NETs, inflammation, and related signaling pathways. RESULTS: Ferritin induces NET formation in a peptidylarginine deiminase 4 (PAD4), neutrophil elastase (NE), and reactive oxygen species (ROS)-dependent manner, thereby exacerbating the inflammatory response. Mechanistically, ferritin induces the expression of neutrophil macrophage scavenger receptor (MSR), which promotes the formation of NETs. Clinically, high levels of ferritin in patients with severe sepsis correlate with NETs-mediated cytokines storm and are proportional to the severity of sepsis-induced lung injury. CONCLUSIONS: In conclusion, we demonstrated that hyper-ferritin can induce systemic inflammation and increase NET formation in an MSR-dependent manner. This process relies on PAD4, NE, and ROS, further aggravating acute lung injury. In the clinic, high serum ferritin levels are associated with elevated NETs and worse lung injury, which suggests a poor prognosis for patients with sepsis. Our study indicated that targeting NETs or MSR could be a potential treatment to alleviate lung damage and systemic inflammation during sepsis. Video Abstract.


Subject(s)
Acute Lung Injury , Extracellular Traps , Sepsis , Humans , Mice , Animals , Extracellular Traps/metabolism , Cytokine Release Syndrome , Reactive Oxygen Species/metabolism , Neutrophils/metabolism , Inflammation/metabolism , Sepsis/complications , Sepsis/metabolism , Acute Lung Injury/metabolism , Receptors, Scavenger/metabolism
8.
Protein J ; 43(2): 283-297, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38265733

ABSTRACT

Scavenger receptors are a protein superfamily that typically consists of one or more repeats of the scavenger receptor cysteine-rich structural domain (SRCRD), which is an ancient and highly conserved protein module. The expression and purification of eukaryotic proteins containing multiple disulfide bonds has always been challenging. The expression systems that are commonly used to express SRCRD proteins mainly consist of eukaryotic protein expression systems. Herein, we established a high-level expression strategy of a Type B SRCRD unit from human salivary agglutinin using the Escherichia coli expression system, followed by a refolding and purification process. The untagged recombinant SRCRD was expressed in E. coli using the pET-32a vector, which was followed by a refolding process using the GSH/GSSG redox system. The SRCRD expressed in E. coli SHuffle T7 showed better solubility after refolding than that expressed in E. coli BL21(DE3), suggesting the importance of the disulfide bond content prior to refolding. The quality of the refolded protein was finally assessed using crystallization and crystal structure analysis. As proteins refolded from inclusion bodies exhibit a high crystal quality and reproducibility, this method is considered a reliable strategy for SRCRD protein expression and purification. To further confirm the structural integrity of the refolded SRCRD protein, the purified protein was subjected to crystallization using sitting-drop vapor diffusion method. The obtained crystals of SRCRD diffracted X-rays to a resolution of 1.47 Å. The solved crystal structure appeared to be highly conserved, with four disulfide bonds appropriately formed. The surface charge distribution of homologous SRCRD proteins indicates that the negatively charged region at the surface is associated with their calcium-dependent ligand recognition. These results suggest that a high-quality SRCRD protein expressed by E. coli SHuffle T7 can be successfully folded and purified, providing new options for the expression of members of the scavenger receptor superfamily.


Subject(s)
Escherichia coli , Protein Refolding , Recombinant Proteins , Escherichia coli/genetics , Escherichia coli/metabolism , Humans , Crystallography, X-Ray , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/biosynthesis , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Crystallization , Agglutinins/chemistry , Agglutinins/genetics , Agglutinins/metabolism , Protein Domains , Gene Expression , Models, Molecular , Cysteine/chemistry , Cysteine/genetics , Receptors, Scavenger/chemistry , Receptors, Scavenger/genetics , Receptors, Scavenger/metabolism
9.
Cell Mol Life Sci ; 81(1): 62, 2024 Jan 27.
Article in English | MEDLINE | ID: mdl-38280036

ABSTRACT

Endothelial injury and dysfunction in the artery wall fuel the process of atherosclerosis. As a key epigenetic regulator, Ash2l (Absent, small, or homeotic-Like 2) is involved in regulating vascular injury and its complications. However, the role of Ash2l in atherosclerosis has not yet been fully elucidated. Here, we found increased Ash2l expression in high-cholesterol diet-fed ApoE-/- mice and oxidized LDL (oxLDL) treated endothelial cells (ECs). Furthermore, Ash2l promoted the scavenger receptors transcription by catalyzing histone H3 lysine 4 (H3K4) trimethylation at the promoter region of transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) and triggered the activation of the pro-inflammatory nuclear factor-kappa B (NF-κB) by enhancing interaction between CD36 and toll-like receptor 4 (TLR4). Meanwhile, enhanced expression of scavenger receptors drove more oxLDL uptake by ECs. In vivo studies revealed that ECs-specific Ash2l knockdown reduced atherosclerotic lesion formation and promoted fibrous cap stability in the aorta of ApoE-/- mice, which was partly associated with a reduced endothelial activation by suppressing scavenger receptors and the uptake of lipids by ECs. Collectively, our findings identify Ash2l as a novel regulator that mediates endothelial injury and atherosclerosis. Targeting Ash2l may provide valuable insights for developing novel therapeutic candidates for atherosclerosis.


Subject(s)
Atherosclerosis , Endothelial Cells , Mice , Animals , Endothelial Cells/metabolism , Lipoproteins, LDL/pharmacology , Lipoproteins, LDL/metabolism , Atherosclerosis/metabolism , NF-kappa B/metabolism , Receptors, Scavenger/metabolism , Apolipoproteins E/genetics , Apolipoproteins E/metabolism
10.
J Investig Med ; 72(4): 370-382, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38264863

ABSTRACT

Morinda officinalis polysaccharide (MOP) is the bioactive ingredient extracted from the root of Morinda officinalis, and Morinda officinalis is applied to treat osteoporosis (OP). The purpose of this study was to determine the role of MOP on human bone marrow mesenchymal stem cells (hBMSCs) and the underlying mechanism. HBMSCs were isolated from bone marrow samples of patients with OP and treated with MOP. Quantitative real-time polymerase chain reaction was adopted to quantify the expression of microRNA-210-3p (miR-210-3p) and scavenger receptor class A member 3 (SCARA3) mRNA. Cell Counting Kit-8 assay was employed to detect cell viability; Terminal-deoxynucleotidyl Transferase Mediated Nick End Labeling assay and flow cytometry were adopted to detect apoptosis; Alkaline Phosphatase (ALP) activity assay kit was applied to detect ALP activity; Western blot was executed to quantify the expression levels of SCARA3, osteogenic and adipogenic differentiation markers. Ovariectomized rats were treated with MOP. Bone mineral density (BMD), serum tartrate-resistant acid phosphatase 5b (TRACP 5b), and N-telopeptide of type I collagen (NTx) levels were assessed by BMD detector and Enzyme-linked immunosorbent assay kits. It was revealed that MOP could promote hBMSCs' viability and osteogenic differentiation and inhibit apoptosis and adipogenic differentiation. MOP could also upregulate SCARA3 expression through repressing miR-210-3p expression. Treatment with MOP increased the BMD and decreased the TRACP 5b and NTx levels in ovariectomized rats. MOP may boost the osteogenic differentiation and inhibit adipogenic differentiation of hBMSCs by miR-210-3p/SCARA3 axis.


Subject(s)
Mesenchymal Stem Cells , MicroRNAs , Morinda , Osteoporosis , Polysaccharides , Animals , Humans , Rats , Bone Marrow/metabolism , Cells, Cultured , Mesenchymal Stem Cells/drug effects , Mesenchymal Stem Cells/metabolism , MicroRNAs/drug effects , MicroRNAs/metabolism , Morinda/chemistry , Morinda/metabolism , Osteogenesis/drug effects , Osteogenesis/genetics , Osteoporosis/drug therapy , Receptors, Scavenger/metabolism , Tartrate-Resistant Acid Phosphatase/metabolism , Polysaccharides/pharmacology , Scavenger Receptors, Class A/drug effects , Scavenger Receptors, Class A/metabolism
11.
J Leukoc Biol ; 115(2): 322-333, 2024 01 19.
Article in English | MEDLINE | ID: mdl-37726110

ABSTRACT

Scavenger receptor A (SRA) is preferentially expressed in macrophages and implicated as a multifunctional pattern recognition receptor for innate immunity. Hepatic macrophages play a primary role in the pathogenesis of alcoholic liver disease. Herein, we observed that SRA expression was significantly increased in the liver tissues of mice with alcohol-related liver injury. SRA-deficient (SRA-/-) mice developed more severe alcohol-induced liver disease than wild-type mice. Enhanced liver inflammation existed in alcohol-challenged SRA-/- mice and was associated with increased Notch activation in hepatic macrophages compared with wild-type control animals. Mechanistically, SRA directly bound with Notch1 and suppressed its S-glutathionylation, thereby inhibiting Notch pathway activation. Further, we determined that the SRA interacted with thioredoxin-1 (Trx-1), a redox-active protein. SRA inhibited Trx-1 dimerization and facilitated the interaction of Trx-1 with Notch1. Application of a Trx-1-specific inhibitory agent during macrophage stimulation abolished SRA-mediated regulation of the Notch pathway and its downstream targets. In summary, our study revealed that SRA plays a critical role in macrophage inflammatory response by targeting Notch1 for its glutathionylation. SRA-mediated negative regulation of Notch activation might serve as a novel therapeutic strategy for alcohol-induced liver injury.


Subject(s)
Chemical and Drug Induced Liver Injury, Chronic , Mice , Animals , Chemical and Drug Induced Liver Injury, Chronic/metabolism , Scavenger Receptors, Class A/metabolism , Macrophages/metabolism , Receptors, Scavenger/metabolism , Liver/metabolism , Immunologic Factors , Ethanol/toxicity , Thioredoxins/genetics , Thioredoxins/metabolism , Mice, Inbred C57BL , Mice, Knockout
12.
J Autoimmun ; 142: 103149, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38006711

ABSTRACT

The hallmark of autoimmune arthritis is the preceding autoantibody production and the following synovial inflammation with hyperplasia and tissue destruction of the joints. The joint inflammation is mediated not only by effector lymphocytes and auto-antibodies but also chronic activation of innate immunity, particularly promoted by the danger-associated molecular patterns (DAMPs). Here we show that apoptosis inhibitor of macrophage (AIM, also called CD5L) protein regulates arthritis by promoting removal of lesional DAMPs both physiologically and therapeutically. When the autoimmune arthritis was promoted by injecting a cocktail of anti-collagen antibodies without type-II collagen immunization, AIM-deficient (AIM-/-) mice exhibited more exacerbated and sustained swelling at multiple joints with greater synovial hyperplasia and bone erosion than wild-type mice. Administration of recombinant AIM (rAIM) reduced S100A8/9, a major DAMP known to be involved in arthritis progression, and decreased various inflammatory cytokines at the lesions in antibody-injected AIM-/- mice, leading to marked prevention of arthritis symptoms. In human rheumatoid arthritis (RA) patients, AIM was more activated via dissociating from IgM-pentamer in response to DAMPs-mediated inflammation both in serum and synovial fluid than in healthy individuals or non-autoimmune osteoarthritis patients, suggesting a disease-regulatory potency of AIM also in human RA patients. Thus, our study implied a therapeutic availability of rAIM to prevent arthritis symptoms targeting DAMPs.


Subject(s)
Arthritis, Experimental , Arthritis, Rheumatoid , Autoimmune Diseases , Animals , Humans , Mice , Apoptosis Regulatory Proteins/metabolism , Autoimmune Diseases/pathology , Hyperplasia/metabolism , Hyperplasia/pathology , Inflammation/metabolism , Receptors, Scavenger/metabolism , Synovial Membrane/pathology
13.
Chem Phys Lipids ; 258: 105362, 2024 01.
Article in English | MEDLINE | ID: mdl-38006924

ABSTRACT

The onset and progression of cardiovascular diseases with the major underlying cause being atherosclerosis, occur during chronic inflammatory persistence in the vascular system, especially within the arterial wall. Such prolonged maladaptive inflammation is driven by macrophages and their key mediators are generally attributed to a disparity in lipid metabolism. Macrophages are the primary cells of innate immunity, endowed with expansive membrane domains involved in immune responses with their signalling systems. During atherosclerosis, the membrane domains and receptors control various active organisations of macrophages. Their scavenger/endocytic receptors regulate the trafficking of intracellular and extracellular cargo. Corresponding influence on lipid metabolism is mediated by their dynamic interaction with scavenger membrane receptors and their integrated mechanisms such as pinocytosis, phagocytosis, cholesterol export/import, etc. This interaction not only results in the functional differentiation of macrophages but also modifies their structural configurations. Here, we reviewed the association of macrophage membrane biomechanics and their scavenger receptor families with lipid metabolites during the event of atherogenesis. In addition, the membrane structure of macrophages and the signalling pathways involved in endocytosis integrated with lipid metabolism are detailed. This article establishes future insights into the scavenger receptors as potential targets for cardiovascular disease prevention and treatment.


Subject(s)
Atherosclerosis , Cardiovascular Diseases , Humans , Cardiovascular Diseases/metabolism , Macrophages , Receptors, Scavenger/metabolism , Cholesterol/metabolism , Inflammation/metabolism
14.
Eur Heart J ; 45(4): 268-283, 2024 Jan 27.
Article in English | MEDLINE | ID: mdl-38036416

ABSTRACT

BACKGROUND AND AIMS: Macrophage-derived foam cells play a causal role during the pathogenesis of atherosclerosis. P2Y6 receptor (P2Y6R) highly expressed has been considered as a disease-causing factor in atherogenesis, but the detailed mechanism remains unknown. This study aims to explore P2Y6R in regulation of macrophage foaming, atherogenesis, and its downstream pathways. Furthermore, the present study sought to find a potent P2Y6R antagonist and investigate the feasibility of P2Y6R-targeting therapy for atherosclerosis. METHODS: The P2Y6R expression was examined in human atherosclerotic plaques and mouse artery. Atherosclerosis animal models were established in whole-body P2Y6R or macrophage-specific P2Y6R knockout mice to evaluate the role of P2Y6R. RNA sequencing, DNA pull-down experiments, and proteomic approaches were performed to investigate the downstream mechanisms. High-throughput Glide docking pipeline from repurposing drug library was performed to find potent P2Y6R antagonists. RESULTS: The P2Y6R deficiency alleviated atherogenesis characterized by decreasing plaque formation and lipid deposition of the aorta. Mechanically, deletion of macrophage P2Y6R significantly inhibited uptake of oxidized low-density lipoprotein through decreasing scavenger receptor A expression mediated by phospholipase Cß/store-operated calcium entry pathways. More importantly, P2Y6R deficiency reduced the binding of scavenger receptor A to CALR, accompanied by dissociation of calreticulin and STIM1. Interestingly, thiamine pyrophosphate was found as a potent P2Y6R antagonist with excellent P2Y6R antagonistic activity and binding affinity, of which the pharmacodynamic effect and mechanism on atherosclerosis were verified. CONCLUSIONS: Macrophage P2Y6R regulates phospholipase Cß/store-operated calcium entry/calreticulin signalling pathway to increase scavenger receptor A protein level, thereby improving foam cell formation and atherosclerosis, indicating that the P2Y6R may be a potential therapeutic target for intervention of atherosclerotic diseases using P2Y6R antagonists including thiamine pyrophosphate.


Subject(s)
Atherosclerosis , Foam Cells , Receptors, Purinergic P2 , Humans , Mice , Animals , Foam Cells/metabolism , Foam Cells/pathology , Calcium/metabolism , Calreticulin/metabolism , Calreticulin/pharmacology , Proteomics , Thiamine Pyrophosphate/metabolism , Thiamine Pyrophosphate/pharmacology , Atherosclerosis/genetics , Macrophages/metabolism , Lipoproteins, LDL/metabolism , Receptors, Scavenger/metabolism , Mice, Knockout , Phospholipases/metabolism , Phospholipases/pharmacology
15.
ACS Infect Dis ; 9(11): 2133-2140, 2023 11 10.
Article in English | MEDLINE | ID: mdl-37910786

ABSTRACT

The success of Staphylococcus aureus as a major cause for endovascular infections depends on effective interactions with blood-vessel walls. We have previously shown that S. aureus uses its wall teichoic acid (WTA), a surface glycopolymer, to attach to endothelial cells. However, the endothelial WTA receptor remained unknown. We show here that the endothelial oxidized low-density lipoprotein receptor 1 (LOX-1) interacts with S. aureus WTA and permits effective binding of S. aureus to human endothelial cells. Purified LOX-1 bound to isolated S. aureus WTA. Ectopic LOX-1 expression led to increased binding of S. aureus wild type but not of a WTA-deficient mutant to a cell line, and LOX-1 blockage prevented S. aureus binding to endothelial cells. Moreover, WTA and LOX-1 expression levels correlated with the efficacy of the S. aureus-endothelial interaction. Thus, LOX-1 is an endothelial ligand for S. aureus, whose blockage may help to prevent or treat severe endovascular infections.


Subject(s)
Staphylococcal Infections , Staphylococcus aureus , Humans , Staphylococcus aureus/genetics , Staphylococcus aureus/metabolism , Endothelial Cells , Teichoic Acids/metabolism , Receptors, Scavenger/metabolism , Scavenger Receptors, Class E/genetics , Scavenger Receptors, Class E/metabolism
16.
J Biol Chem ; 299(11): 105325, 2023 11.
Article in English | MEDLINE | ID: mdl-37805141

ABSTRACT

In multicellular organisms, a variety of lipid-protein particles control the systemic flow of triacylglycerides, cholesterol, and fatty acids between cells in different tissues. The chemical modification by oxidation of these particles can trigger pathological responses, mediated by a group of membrane proteins termed scavenger receptors. The lectin-like oxidized low-density lipoprotein (LOX-1) scavenger receptor binds to oxidized low-density lipoprotein (oxLDL) and mediates both signaling and trafficking outcomes. Here, we identified five synthetic proteins termed Affimers from a phage display library, each capable of binding recombinant LOX-1 extracellular (oxLDL-binding) domain with high specificity. These Affimers, based on a phytocystatin scaffold with loop regions of variable sequence, were able to bind to the plasma membrane of HEK293T cells exclusively when human LOX-1 was expressed. Binding and uptake of fluorescently labeled oxLDL by the LOX-1-expressing cell model was inhibited with subnanomolar potency by all 5 Affimers. ERK1/2 activation, stimulated by oxLDL binding to LOX-1, was also significantly inhibited (p < 0.01) by preincubation with LOX-1-specific Affimers, but these Affimers had no direct agonistic effect. Molecular modeling indicated that the LOX-1-specific Affimers bound predominantly via their variable loop regions to the surface of the LOX-1 lectin-like domain that contains a distinctive arrangement of arginine residues previously implicated in oxLDL binding, involving interactions with both subunits of the native, stable scavenger receptor homodimer. These data provide a new class of synthetic tools to probe and potentially modulate the oxLDL/LOX-1 interaction that plays an important role in vascular disease.


Subject(s)
MAP Kinase Signaling System , Scavenger Receptors, Class E , Humans , Scavenger Receptors, Class E/genetics , Scavenger Receptors, Class E/chemistry , Scavenger Receptors, Class E/metabolism , HEK293 Cells , Lipoproteins, LDL/metabolism , Receptors, Scavenger/metabolism , Lectins/metabolism
17.
Elife ; 122023 09 14.
Article in English | MEDLINE | ID: mdl-37706489

ABSTRACT

The acquisition of distinct branch sizes and shapes is a central aspect in tubular organ morphogenesis and function. In the Drosophila airway tree, the interplay of apical extracellular matrix (ECM) components with the underlying membrane and cytoskeleton controls tube elongation, but the link between ECM composition with apical membrane morphogenesis and tube size regulation is elusive. Here, we characterized Emp (epithelial membrane protein), a Drosophila CD36 homolog belonging to the scavenger receptor class B protein family. emp mutant embryos fail to internalize the luminal chitin deacetylases Serp and Verm at the final stages of airway maturation and die at hatching with liquid filled airways. Emp localizes in apical epithelial membranes and shows cargo selectivity for LDLr-domain containing proteins. emp mutants also display over elongated tracheal tubes with increased levels of the apical proteins Crb, DE-cad, and phosphorylated Src (p-Src). We show that Emp associates with and organizes the ßH-Spectrin cytoskeleton and is itself confined by apical F-actin bundles. Overexpression or loss of its cargo protein Serp lead to abnormal apical accumulations of Emp and perturbations in p-Src levels. We propose that during morphogenesis, Emp senses and responds to luminal cargo levels by initiating apical membrane endocytosis along the longitudinal tube axis and thereby restricts airway elongation.


Subject(s)
Drosophila Proteins , Drosophila melanogaster , Endocytosis , Receptors, Scavenger , Animals , Drosophila melanogaster/genetics , Drosophila melanogaster/metabolism , Drosophila Proteins/metabolism , Morphogenesis , Receptors, Scavenger/metabolism , Trachea/metabolism
19.
Methods Mol Biol ; 2693: 193-208, 2023.
Article in English | MEDLINE | ID: mdl-37540436

ABSTRACT

Extracellular heat shock proteins (HSP) play important roles in cell signaling and immunity. Many of these effects are mediated by surface receptors expressed on a wide range of cell types, including immune cells. We have investigated the nature of such proteins by cloning candidate receptors into cells (CHO-K1) with the rare property of being null for HSP binding. Using this approach, we have discovered that mammalian and eukaryotic Hsp70 binds avidly to at least three classes of receptor including: (1) c-type lectin receptors (CLR), (2) scavenger receptors (SR) and (3) lectins. However, the structural nature of the receptor-ligand interactions is not currently clear. Hsp70 can bind to LOX-1 (a member of both the CLR and SR), with the c-type lectin binding domain (CTLD), to the SR family members SREC-I and FEEL-1/CLEVER-1/STABILIN-1, which by contrast have arrays of EGF-like repeats in their extracellular domains as well. In this chapter, we will discuss: (1) methods for the discovery of HSP receptors, (2) approaches to the study of individual receptors in cells that contain multiple such receptors and (3) methods for investigating HSP receptor function in vivo.


Subject(s)
HSP70 Heat-Shock Proteins , Molecular Chaperones , Animals , Heat-Shock Proteins/metabolism , Receptors, Scavenger/metabolism , Lectins, C-Type/metabolism , Mammals/metabolism
20.
Exp Anim ; 72(4): 535-545, 2023 Nov 09.
Article in English | MEDLINE | ID: mdl-37407484

ABSTRACT

CD36 (also known as scavenger receptor B2) is a multifunctional receptor that mediates lipid uptake, advanced oxidation protein products, and immunological recognition, and has roles in lipid accumulation, apoptosis, as well as in metastatic colonization in cancer. CD36 is involved in tumor immunity, metastatic invasion, and therapy resistance through various molecular mechanisms. Targeting CD36 has emerged as an effective strategy for tumor immunotherapy. In this study, we have successfully generated a novel hCD36 mouse (Unless otherwise stated, hCD36 mouse below refer to homozygous hCD36 mouse) strain where the sequences encoding the extracellular domains of the mouse Cd36 gene were replaced with the corresponding human sequences. The results showed that the hCD36 mice only expressed human CD36, and the proportion of each lymphocyte was not significantly changed compared with wild-type mice. Furthermore, CD36 monoclonal antibody could significantly inhibit tumor growth after treatment. Therefore, the hCD36 mouse represent a validated preclinical mouse model for the evaluation of tumor immunotherapy targeting CD36.


Subject(s)
CD36 Antigens , Neoplasms , Mice , Humans , Animals , CD36 Antigens/genetics , CD36 Antigens/metabolism , Receptors, Scavenger/metabolism , Neoplasms/genetics , Neoplasms/therapy , Lipids
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