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Molecules (Basel, Switzerland) Dec 2023Lipid membrane nanodomains or lipid rafts are 10-200 nm diameter size cholesterol- and sphingolipid-enriched domains of the plasma membrane, gathering many proteins with... (Review)
Review
Lipid membrane nanodomains or lipid rafts are 10-200 nm diameter size cholesterol- and sphingolipid-enriched domains of the plasma membrane, gathering many proteins with different roles. Isolation and characterization of plasma membrane proteins by differential centrifugation and proteomic studies have revealed a remarkable diversity of proteins in these domains. The limited size of the lipid membrane nanodomain challenges the simple possibility that all of them can coexist within the same lipid membrane domain. As caveolin-1, flotillin isoforms and gangliosides are currently used as neuronal lipid membrane nanodomain markers, we first analyzed the structural features of these components forming nanodomains at the plasma membrane since they are relevant for building supramolecular complexes constituted by these molecular signatures. Among the proteins associated with neuronal lipid membrane nanodomains, there are a large number of proteins that play major roles in calcium signaling, such as ionotropic and metabotropic receptors for neurotransmitters, calcium channels, and calcium pumps. This review highlights a large variation between the calcium signaling proteins that have been reported to be associated with isolated caveolin-1 and flotillin-lipid membrane nanodomains. Since these calcium signaling proteins are scattered in different locations of the neuronal plasma membrane, i.e., in presynapses, postsynapses, axonal or dendritic trees, or in the neuronal soma, our analysis suggests that different lipid membrane-domain subtypes should exist in neurons. Furthermore, we conclude that classification of lipid membrane domains by their content in calcium signaling proteins sheds light on the roles of these domains for neuronal activities that are dependent upon the intracellular calcium concentration. Some examples described in this review include the synaptic and metabolic activity, secretion of neurotransmitters and neuromodulators, neuronal excitability (long-term potentiation and long-term depression), axonal and dendritic growth but also neuronal cell survival and death.
Topics: Caveolin 1; Calcium Signaling; Calcium; Proteomics; Membrane Microdomains; Neurons; Gangliosides; Neurotransmitter Agents
PubMed: 38067638
DOI: 10.3390/molecules28237909 -
Chembiochem : a European Journal of... Jul 2023Glycosphingolipid (GSL) and glycosylphosphatidylinositol (GPI) are the two major glycolipids expressed by eukaryotic cells, and their metabolisms share the same... (Review)
Review
Glycosphingolipid (GSL) and glycosylphosphatidylinositol (GPI) are the two major glycolipids expressed by eukaryotic cells, and their metabolisms share the same machineries. Moreover, both GSLs and GPI-anchored proteins (GPI-APs) are localized in the cholesterol-rich regions, namely the lipid rafts, of the cell membrane, where many other signaling molecules are compartmentalized as well. Therefore, the interaction between GSLs and GPI-APs and their interactions with other molecules in the lipid rafts are inevitable. This review is focused on the influences of GSLs and GPI-APs on each other's biosynthesis, trafficking, cell membrane distribution, and biological functions, such as signal transduction.
Topics: Glycosphingolipids; Glycosylphosphatidylinositols; Cell Membrane; Proteins; Membrane Microdomains
PubMed: 36935354
DOI: 10.1002/cbic.202200761 -
Science Advances Sep 2023The mechanistic target of rapamycin complex 1 (mTORC1) is part of the amino acid sensing machinery that becomes activated on the endolysosomal surface in response to...
The mechanistic target of rapamycin complex 1 (mTORC1) is part of the amino acid sensing machinery that becomes activated on the endolysosomal surface in response to nutrient cues. Branched actin generated by WASH and Arp2/3 complexes defines endolysosomal microdomains. Here, we find mTORC1 components in close proximity to endolysosomal actin microdomains. We investigated for interactors of the mTORC1 lysosomal tether, RAGC, by proteomics and identified multiple actin filament capping proteins and their modulators. Perturbation of RAGC function affected the size of endolysosomal actin, consistent with a regulation of actin filament capping by RAGC. Reciprocally, the pharmacological inhibition of actin polymerization or alteration of endolysosomal actin obtained upon silencing of WASH or Arp2/3 complexes impaired mTORC1 activity. Mechanistically, we show that actin is required for proper association of RAGC and mTOR with endolysosomes. This study reveals an unprecedented interplay between actin and mTORC1 signaling on the endolysosomal system.
Topics: Mechanistic Target of Rapamycin Complex 1; Actins; Signal Transduction; Actin Cytoskeleton; Lysosomes
PubMed: 37703363
DOI: 10.1126/sciadv.add9084 -
Mitochondria-associated membrane collapse impairs TBK1-mediated proteostatic stress response in ALS.Proceedings of the National Academy of... Nov 2023The organelle contact site of the endoplasmic reticulum and mitochondria, known as the mitochondria-associated membrane (MAM), is a multifunctional microdomain in...
The organelle contact site of the endoplasmic reticulum and mitochondria, known as the mitochondria-associated membrane (MAM), is a multifunctional microdomain in cellular homeostasis. We previously reported that MAM disruption is a common pathological feature in amyotrophic lateral sclerosis (ALS); however, the precise role of MAM in ALS was uncovered. Here, we show that the MAM is essential for TANK-binding kinase 1 (TBK1) activation under proteostatic stress conditions. A MAM-specific E3 ubiquitin ligase, autocrine motility factor receptor, ubiquitinated nascent proteins to activate TBK1 at the MAM, which results in ribosomal protein degradation. MAM or TBK1 deficiency under proteostatic stress conditions resulted in increased cellular vulnerability in vitro and motor impairment in vivo. Thus, MAM disruption exacerbates proteostatic stress via TBK1 inactivation in ALS. Our study has revealed a proteostatic mechanism mediated by the MAM-TBK1 axis, highlighting the physiological importance of the organelle contact sites.
Topics: Humans; Amyotrophic Lateral Sclerosis; Mitochondria; Mitochondrial Membranes; Endoplasmic Reticulum; Protein Serine-Threonine Kinases
PubMed: 37967220
DOI: 10.1073/pnas.2315347120 -
Circulation Research Jul 2023Beta-2 adrenergic receptors (βARs) but not beta-2 adrenergic receptors (βARs) form a functional complex with L-type Ca channels (LTCCs) on the cardiomyocyte membrane....
BACKGROUND
Beta-2 adrenergic receptors (βARs) but not beta-2 adrenergic receptors (βARs) form a functional complex with L-type Ca channels (LTCCs) on the cardiomyocyte membrane. However, how microdomain localization in the plasma membrane affects the function of these complexes is unknown. We aim to study the coupling between LTCC and β adrenergic receptors in different cardiomyocyte microdomains, the distinct involvement of PKA and CAMKII (Ca/calmodulin-dependent protein kinase II) and explore how this functional complex is disrupted in heart failure.
METHODS
Global signaling between LTCCs and β adrenergic receptors was assessed with whole-cell current recordings and western blot analysis. Super-resolution scanning patch-clamp was used to explore the local coupling between single LTCCs and βAR or βAR in different membrane microdomains in control and failing cardiomyocytes.
RESULTS
LTCC open probability (Po) showed an increase from 0.054±0.003 to 0.092±0.008 when βAR was locally stimulated in the proximity of the channel (<350 nm) in the transverse tubule microdomain. In failing cardiomyocytes, from both rodents and humans, this transverse tubule coupling between LTCC and βAR was lost. Interestingly, local stimulation of βAR did not elicit any change in the Po of LTCCs, indicating a lack of proximal functional interaction between the two, but we confirmed a general activation of LTCC via βAR. By using blockers of PKA and CaMKII and a Caveolin-3-knockout mouse model, we conclude that the βAR-LTCC regulation requires the presence of caveolin-3 and the activation of the CaMKII pathway. By contrast, at a cellular "global" level PKA plays a major role downstream βAR and results in an increase in LTCC current.
CONCLUSIONS
Regulation of the LTCC activity by proximity coupling mechanisms occurs only via βAR, but not βAR. This may explain how βARs tune the response of LTCCs to adrenergic stimulation in healthy conditions. This coupling is lost in heart failure; restoring it could improve the adrenergic response of failing cardiomyocytes.
Topics: Mice; Animals; Humans; Caveolin 3; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Heart Failure; Myocytes, Cardiac; Receptors, Adrenergic, beta; Receptors, Adrenergic, beta-2; Adrenergic Agents; Calcium Channels, L-Type
PubMed: 37313722
DOI: 10.1161/CIRCRESAHA.123.322508 -
Frontiers in Pharmacology 2023Part of the broader glycosphingolipid family, gangliosides are composed of a ceramide bound to a sialic acid-containing glycan chain, and locate at the plasma membrane.... (Review)
Review
Part of the broader glycosphingolipid family, gangliosides are composed of a ceramide bound to a sialic acid-containing glycan chain, and locate at the plasma membrane. Gangliosides are produced through sequential steps of glycosylation and sialylation. This diversity of composition is reflected in differences in expression patterns and functions of the various gangliosides. Ganglioside GD2 designates different subspecies following a basic structure containing three carbohydrate residues and two sialic acids. GD2 expression, usually restrained to limited tissues, is frequently altered in various neuroectoderm-derived cancers. While GD2 is of evident interest, its glycolipid nature has rendered research challenging. Physiological GD2 expression has been linked to developmental processes. Passing this stage, varying levels of GD2, physiologically expressed mainly in the central nervous system, affect composition and formation of membrane microdomains involved in surface receptor signaling. Overexpressed in cancer, GD2 has been shown to enhance cell survival and invasion. Furthermore, binding of antibodies leads to immune-independent cell death mechanisms. In addition, GD2 contributes to T-cell dysfunction, and functions as an immune checkpoint. Given the cancer-associated functions, GD2 has been a source of interest for immunotherapy. As a potential biomarker, methods are being developed to quantify GD2 from patients' samples. In addition, various therapeutic strategies are tested. Based on initial success with antibodies, derivates such as bispecific antibodies and immunocytokines have been developed, engaging patient immune system. Cytotoxic effectors or payloads may be redirected based on anti-GD2 antibodies. Finally, vaccines can be used to mount an immune response in patients. We review here the pertinent biological information on GD2 which may be of use for optimizing current immunotherapeutic strategies.
PubMed: 37670947
DOI: 10.3389/fphar.2023.1249929 -
Cellular & Molecular Biology Letters Oct 2023Membrane rafts play a crucial role in the regulation of many important biological processes. Our previous data suggest that specific interactions of flotillins with MPP1...
BACKGROUND
Membrane rafts play a crucial role in the regulation of many important biological processes. Our previous data suggest that specific interactions of flotillins with MPP1 are responsible for membrane raft domain organization and regulation in erythroid cells. Interaction of the flotillin-based protein network with specific membrane components underlies the mechanism of raft domain formation and regulation, including in cells with low expression of MPP1.
METHODS
We sought to identify other flotillin partners via the immobilized recombinant flotillin-2-based affinity approach and mass spectrometry technique. The results were further confirmed via immunoblotting and via co-immunoprecipitation. In order to study the effect of the candidate protein on the physicochemical properties of the plasma membrane, the gene was knocked down via siRNA, and fluorescence lifetime imaging microscopy and spot-variation fluorescence correlation spectroscopy was employed.
RESULTS
EFR3A was identified as a candidate protein that interacts with flotillin-2. Moreover, this newly discovered interaction was demonstrated via overlay assay using recombinant EFR3A and flotillin-2. EFR3A is a stable component of the detergent-resistant membrane fraction of HeLa cells, and its presence was sensitive to the removal of cholesterol. While silencing the EFR3A gene, we observed decreased order of the plasma membrane of living cells or giant plasma membrane vesicles derived from knocked down cells and altered mobility of the raft probe, as indicated via fluorescence lifetime imaging microscopy and spot-variation fluorescence correlation spectroscopy. Moreover, silencing of EFR3A expression was found to disturb epidermal growth factor receptor and phospholipase C gamma phosphorylation and affect epidermal growth factor-dependent cytosolic Ca concentration.
CONCLUSIONS
Altogether, our results suggest hitherto unreported flotillin-2-EFR3A interaction, which might be responsible for membrane raft organization and regulation. This implies participation of this interaction in the regulation of multiple cellular processes, including those connected with cell signaling which points to the possible role in human health, in particular human cancer biology.
Topics: Humans; Cell Membrane; Epidermal Growth Factor; HeLa Cells; Protein Binding; Membrane Microdomains; Adaptor Proteins, Signal Transducing; Membrane Proteins
PubMed: 37880612
DOI: 10.1186/s11658-023-00497-y -
Journal of Obstetrics and Gynaecology :... Dec 2023BAG3 is a co-chaperone BAG family protein that plays important roles in protein homeostasis, cell survival, cell motility, and tumour metastasis. This study aimed to...
BAG3 is a co-chaperone BAG family protein that plays important roles in protein homeostasis, cell survival, cell motility, and tumour metastasis. This study aimed to clarify the clinicopathological and prognostic implications of mRNA expression in tumours. We performed bioinformatics analysis on mRNA expression using TCGA, XIANTAO, UALCAN, and Kaplan-Meier plotter databases. mRNA expression was downregulated in breast and endometrial cancers and positively correlated with favourable PAM50 subtyping in breast cancer,clinical stage and short overall survival in ovarian cancer and negatively correlated with T stage, clinical stage, and histological grade in cervical and endometrial cancers. The top -related pathways included ligand-receptor interactions and activity, DNA packaging and nucleosomes, hormonal responses, membrane regions, microdomains and rafts, and endosomes in breast cancer; ligand-receptor interactions, transmembrane transporters and channels, cell adhesion, and keratinisation in cervical cancer; ligand-receptor interactions, anion transmembrane transporters, lipoproteins, keratinisation, cell adhesion, and protein processing in endometrial cancer; metabolism of porphyrin, chlorophyll, pentose, uronic acid, ascorbate, and alternate and cell adhesion in ovarian cancer. expression could represent a potential marker for carcinogenesis, histogenesis, aggressive behaviours, and prognosis in gynecological cancers.IMPACT STATEMENT BAG3 regulates cell activity, autophagy, and resistance to apoptosis through multiple domains and plays an important role in tumour development. BAG3 positively regulates tumour cell invasion and migration in cervical and ovarian cancers. BAG3 expression is closely associated with histogenesis, clinicopathology, and prognosis in gynecological cancers and is involved in signalling pathways associated with the control of cell proliferation, migration, invasion, and drug resistance in tumours. Abnormal BAG3 expression can be employed as a possible marker of tumour development, invasion, and prognosis, providing new ideas for treating cancer.
Topics: Female; Humans; Prognosis; Cell Line, Tumor; Adaptor Proteins, Signal Transducing; RNA, Messenger; Ligands; Apoptosis Regulatory Proteins; Ovarian Neoplasms; Computational Biology; Endometrial Neoplasms; Breast Neoplasms
PubMed: 37377218
DOI: 10.1080/01443615.2023.2228899 -
FEBS Open Bio Sep 2023Gangliosides are functional components of membrane lipid rafts that control critical functions in cell communication. Many pathologies involve raft gangliosides, which... (Review)
Review
Gangliosides are functional components of membrane lipid rafts that control critical functions in cell communication. Many pathologies involve raft gangliosides, which therefore represent an approach of choice for developing innovative therapeutic strategies. Beginning with a discussion of what a disease is (and is not), this review lists the major human pathologies that involve gangliosides, which includes cancer, diabetes, and infectious and neurodegenerative diseases. In most cases, the problem is due to a protein whose binding to gangliosides either creates a pathological condition or impairs a physiological function. Then, I draw up an inventory of the different molecular mechanisms of protein-ganglioside interactions. I propose to classify the ganglioside-binding domains of proteins into four categories, which I name GBD-1, GBD-2, GBD-3, and GBD-4. This structural and functional classification could help to rationalize the design of innovative molecules capable of disrupting the binding of selected proteins to gangliosides without generating undesirable effects. The biochemical specificities of gangliosides expressed in the human brain must also be taken into account to improve the reliability of animal models (or any animal-free alternative) of Alzheimer's and Parkinson's diseases.
Topics: Humans; Gangliosides; Reproducibility of Results; Parkinson Disease; Brain; Membrane Microdomains
PubMed: 37052878
DOI: 10.1002/2211-5463.13612 -
Virulence Dec 2023is an emerging spore-forming anaerobe that is often observed in -associated inflammatory bowel disease (IBD) exacerbations. Unlike , neither produces toxins nor...
is an emerging spore-forming anaerobe that is often observed in -associated inflammatory bowel disease (IBD) exacerbations. Unlike , neither produces toxins nor possesses toxin-encoding genetic loci, but is commonly found in both intestinal and extra-intestinal infections. Membrane lipid rafts are composed of dynamic assemblies of cholesterol and sphingolipids, allowing bacteria to gain access to cells. However, the direct interaction between and lipid rafts that confers bacteria the ability to disrupt the intestinal barrier and induce pathogenesis remains unclear. In this study, we investigated the associations among nucleotide-binding oligomerization domain containing 2 (NOD2), lipid rafts, and cytotoxicity in -infected gut epithelial cells. Our results revealed that lipid rafts were involved in -induced NOD2 expression and nuclear factor (NF)-κB activation, triggering an inflammatory response. Reducing cholesterol by simvastatin significantly dampened -induced cell death, indicating that the -induced pathogenicity of cells was lipid raft-dependent. These results demonstrate that NOD2 mobilization into membrane rafts in response to -induced cytotoxicity results in aggravated pathogenicity.
Topics: Clostridioides difficile; Clostridium; NF-kappa B; Membrane Microdomains; Cholesterol
PubMed: 37798913
DOI: 10.1080/21505594.2023.2265048