Dynamic nitrosation - palmitoylation of CD36 regulates serum lipids
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PROVIDER: PRJNA1083931 | ENA |
REPOSITORIES: ENA
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Project description:Regulation of endothelial cell (EC) lipid content is crucial for cell and organ function. During obesity, ECs become lipid laden leading to lipotoxicity and endothelial dysfunction which further contribute to metabolic syndrome progression. Here, we demonstrate a novel pathway by which the endothelium, via eNOS-dependent nitrosation, inhibits excess lipid accumulation during hyperlipidemic conditions in obesity. In the vasculature, nitric oxide has been reported as a potent vasodilator. However, we highlight a new role for nitric oxide as a modulator of serum lipids. We show this occurs as a result of the downregulation of Cav1, a potent negative regulator of endothelial nitric oxide synthase, increasing EC endogenous nitric oxide synthesis. Using EC-specific Cav1 knockout mice, we are able to increase nitric oxide in vivo. This increased nitric oxide leads to nitrosation of cysteines 3 and 466 on the cytoplasmic tails of CD36, a fatty acid translocase, disrupting palmitoylation of these residues and subsequently inhibiting trafficking of CD36 to the plasma membrane. Together, this work suggests that CD36 nitrosation occurs as a protective mechanism to prevent lipotoxicity and EC dysfunction during the progression of metabolic syndrome.
2024-12-31 | GSE260897 | GEO
Project description:Amyloid-beta (Aβ) is a key factor in the onset and progression of Alzheimer's disease (AD). Selenium (Se) compounds show promise in AD treatment. Here, we reveal that selenoprotein K (SELENOK), a selenoprotein involved in immune regulation and potentially related to AD pathology, plays a critical role in microglial immune response, migration, and phagocytosis. In vivo and in vitro studies corroborate that SELENOK deficiency inhibits microglial Aβ phagocytosis, exacerbating cognitive deficits in 5xFAD mice, which are reversed by SELENOK overexpression. Mechanistically, SELENOK is involved in CD36 palmitoylation through DHHC6, regulating CD36 localization to microglial plasma membranes and thus impacting Aβ phagocytosis. CD36 palmitoylation is reduced in the brains of AD patients and mice. Se supplementation promotes SELENOK expression and CD36 palmitoylation, enhancing microglial Aβ phagocytosis and mitigating AD progression. We have identified the regulatory mechanisms from Se-dependent selenoproteins to Aβ pathology, providing novel insights into potential therapeutic strategies involving Se and selenoproteins.
2024-02-29 | GSE255034 | GEO
Project description:SELENOK-Dependent CD36 Palmitoylation Regulates Microglial Functions and Aβ Phagocytosis
| PRJNA1073397 | ENA
Project description:T cell metabolic fitness plays a pivotal role in anti-tumor immunity and metabolic deregulation causes T cell dysfunction in cancer. We identify that CD36 limits anti-tumor CD8+ T cell effector functions through lipid peroxidation. In murine tumors, oxidized phospholipids (OxPLs) were highly abundant and CD8+ TILs increased uptake and accumulation of lipids and lipid peroxidation. Functionally ‘exhausted’ CD8+ TILs increased CD36 expression and CD36-deficient CD8+ TILs had more robust anti-tumor activity and cytokine production than wild-type cells. We further show that CD36 promotes uptake of oxidized low-density lipoproteins (OxLDL), induces lipid peroxidation in CD8+ TILs, and enhances p38 kinase phosphorylation. Moreover, we found that OxLDL inhibits CD8+ T cell functions in a CD36/p38-dependent manner. Furthermore, glutathione peroxidase 4 (GPX4) over-expression lowers lipid peroxidation and restores functionalities in CD8+ TILs. These results define a key role for an oxidized lipid-CD36-p38 axis in promoting intratumoral CD8+ T cell dysfunction.
2021-03-31 | GSE171194 | GEO
Project description:Postprandial dyslipidemia is a recognized risk factor for atherosclerosis. High-density lipoprotein (HDL)-mediated reverse cholesterol transport plays a crucial role in mitigating this risk by clearing postprandial lipids. This study aimed to investigate the impact of esculetin, a 4-Hydroxycoumarin, on postprandial cholesterol metabolism and excretion after a high-fat meal. Esculetin significantly elevated postprandial HDL cholesterol levels in serum and postprandial bile acid levels in bile, and altered serum metabolomics in mice fed a high-fat meal, indicating esculetin promotes HDL-driven cholesterol excretion after a high-fat meal. Furthermore, esculetin administration in mice led to an increase in the ratio and phagocytic activity of a subset of adipose tissue macrophages (ATMs) expressing high levels of CD36 and Tim4. Inhibition of CD36 by Sulfo-N-succinimidyl oleate (SSO) blocked esculetin-induced elevation of postprandial serum HDL and bile acid levels in bile. Additionally, esculetin demonstrated the ability to increase the uptake of oxidized LDL (ox-LDL) via CD36 in a macrophage cell line, which might involve alteration of the epigenetic landscape controlled by CCAAT enhancer-binding protein beta (C/EBPβ). Esculetin-induced increased uptake of ox-LDL and elevation of CD36 was inhibited in C/EBPβ-deficient cells. A relatively higher expression of C/EBPβ was observed in CD36+ ATMs, and esculetin increased the ratio of C/EBPβ+ CD36+ ATMs in mice fed a lipid-rich meal. Moreover, the direct interaction between esculetin and C/EBPβ were observed by Terahertz chemical microscope. Overall, these findings suggest esculetin promotes HDL-mediated postprandial cholesterol excretion by directly binding to C/EBPβ and enhancing CD36-dependent phagocytosis in ATMs.
2024-06-12 | GSE234771 | GEO
Project description:Monocytes and macrophages as components of innate immunity are critical for both homeostasis and inflammation. The scavenger receptor CD36, highly expressed in macrophages, promotes immunological responses mediated by recognition of molecular patterns on pathogens or endogenous ligands on apoptotic cells. CD36 mediated lipid uptake also allows metabolic adaptations that influence macrophage phenotype and polarization. CD36 binds diverse lipids including fatty acids and various lipoproteins, which could exert differential effects on macrophage conversion. Previous studies reported opposite outcomes due to CD36-mediated lipid uptake; macrophages converted to either an inflammatory or an alternatively activated phenotype. To determine the role of this receptor in vivo in the presence of physiological lipid sources, we created macrophage-specific CD36 knockout mice. Using zymosan-induced peritonitis to activate immune cells, we show through single cell RNA sequencing analysis that a broad variety of resident and infiltrated immune cells are present in the peritoneum 72h after the initial stimulus. CD36 deficiency did not affect the numbers of cells during the infiltration and resolution phases, but CD36 deficiency altered the macrophage transcriptome. Pathways related to innate immunity, antigen presentation and oxidative phosphorylation were upregulated in macrophages with CD36 deficiency, whereas those related to efferocytosis, adaptive immunity and B cell activation were downregulated. Despite these gene changes, neither immunoglobulin production nor peritoneal efferocytosis was altered by macrophage CD36 deficiency, nor were there changes in the numbers of circulating white blood cells. Thus, CD36 deficiency does not reduce the inflammatory phenotype of induced peritoneal macrophages.
2024-05-31 | GSE210795 | GEO
Project description:Fatty acids (FAs) are essential nutrients, but how they are transported into cells remains unclear. Here, we show that FAs trigger caveolae-dependent CD36 internalization, which in turn delivers FAs into adipocytes. During the process, binding of FAs to CD36 activates its downstream kinase LYN, which phosphorylates DHHC5, the palmitoyl acyltransferase of CD36, at Tyr91 and inactivates it. CD36 then gets depalmitoylated by APT1 and recruits another tyrosine kinase SYK to phosphorylate JNK and VAVs to initiate endocytic uptake of FAs. Blocking CD36 internalization by inhibiting APT1, LYN or SYK abolishes CD36-dependent FA uptake. Restricting CD36 at either palmitoylated or depalmitoylated state eliminates its FA uptake activity, indicating an essential role of dynamic palmitoylation of CD36. Furthermore, blocking endocytosis by targeting LYN or SYK inhibits CD36-dependent lipid droplet growth in adipocytes and high-fat-diet induced weight gain in mice. Our study has uncovered a dynamic palmitoylation-regulated endocytic pathway to take up FAs.
| S-EPMC7505845 | biostudies-literature
Project description:Palmitoylation is the reversible addition of palmitate to cysteine via a thioester linkage. The reversible nature of this modification makes it a prime candidate as a mechanism for regulating signal transduction in T-cell receptor signaling. Following stimulation of the T-cell receptor we find a number of proteins are newly palmitoylated, including those involved in vesicle-mediated transport and Ras signal transduction. Among these stimulation-dependent palmitoylation targets are the v-SNARE VAMP7, important for docking of vesicular LAT during TCR signaling, and the largely undescribed palmitoyl acyltransferase DHHC18 that is expressed in two isoforms in T cells. Using our newly developed On-Plate Palmitoylation Assay (OPPA), we show DHHC18 is capable of palmitoylating VAMP7 at Cys183. Cellular imaging shows that the palmitoylation-deficient protein fails to be retained at the Golgi.
2021-09-09 | PXD018703 | Pride
Project description:Palmitoylation is the reversible addition of palmitate to cysteine via a thioester linkage. The reversible nature of this modification makes it a prime candidate as a mechanism for regulating signal transduction in T-cell receptor signaling. Following stimulation of the T-cell receptor we find a number of proteins are newly palmitoylated, including those involved in vesicle-mediated transport and Ras signal transduction. Among these stimulation-dependent palmitoylation targets are the v-SNARE VAMP7, important for docking of vesicular LAT during TCR signaling, and the largely undescribed palmitoyl acyltransferase DHHC18 that is expressed in two isoforms in T cells. Using our newly developed On-Plate Palmitoylation Assay (OPPA), we show DHHC18 is capable of palmitoylating VAMP7 at Cys183. Cellular imaging shows that the palmitoylation-deficient protein fails to be retained at the Golgi. This dataset includes the experiments previously reported in: Morrison et al. Quantitative analysis of the human T cell palmitome. Sci Rep. 5, Article number: 11598 (2015)
2021-09-09 | PXD018710 | Pride
Project description:Oxidized Lipids and CD36-Mediated Lipid Peroxidation in CD8 T Cells Suppress Anti-Tumor Immune Responses
| PRJNA718612 | ENA