The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Senitiroh Hakomori - One of the best experts on this subject based on the ideXlab platform.
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regulation of epidermal growth factor receptor through interaction of ganglioside GM3 with glcnac of n linked glycan of the receptor demonstration in ldld cells
Neurochemical Research, 2011Co-Authors: Kazuko Handa, Senitiroh Hakomori, Feng GuanAbstract:We investigated interaction of GM3 with N-acetylglucosamine (GlcNAc) termini of N-linked glycans of epidermal growth factor receptor (EGFR), as the underlying mechanism for inhibitory effect of GM3 on EGFR activation, using ldlD cells transfected with EGFR gene. These cells, defective in UDP-Gal/UDP-GalNAc 4-epimerase, are incapable of synthesizing galactose (Gal)-containing glycans, unless Gal is provided in culture (+Gal). Key observations: (1) Expression of GlcNAc termini was high in −Gal cells, and strongly reduced in +Gal cells. (2) Comparative study of inhibitory effect of exogenously-added GM3 on EGFR activation in +Gal versus −Gal cells indicated that higher level of GlcNAc termini on EGFR is correlated with greater inhibitory effect of GM3. (3) GM3-, but not GM1-, coated beads bound to EGFR in lysate of −Gal cells, which have highly exposed GlcNAc termini. Such binding was inhibited in the presence of EDTA, similarly to other carbohydrate-carbohydrate interactions.
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lyso GM3 its dimer and multimer their synthesis and their effect on epidermal growth factor induced receptor tyrosine kinase
Glycoconjugate Journal, 2007Co-Authors: Naoko Watanabe, Yoshimi Murozuka, Kenichi Hatanaka, Senitiroh HakomoriAbstract:Glycosphingolipids, particularly gangliosides, are known to modulate growth factor receptor tyrosine kinase. A well-documented example is the inhibitory effect of GM3 on kinase associated with epidermal growth factor receptor (EGFR) in human epidermoid carcinoma A431 cells. Lyso-GM3 was detected as a minor component in A431 cells, and may function as an auxiliary factor in GM3-dependent inhibition of EGFR. We studied the inhibitory effect of chemically synthesized GM3, lyso-GM3, and its derivatives, on EGFR function, based on their interaction in membrane microdomain, with the following major findings: (1) GM3, EGFR, and caveolin coexist, but tetraspanins CD9 and CD82 are essentially absent, within the same low-density membrane fraction, separated by sucrose density gradient ultracentrifugation. (2) Strong interaction between EGFR and GM3 was indicated by increasing binding of EGFR to GM3-coated polystyrene beads, in a GM3 dose-dependent manner. Confocal microscopy results suggested that three components in the microdomain (GM3, EGFR, and caveolin) are closely associated. (3) Lyso-GM3 or lyso-GM3 dimer strongly inhibited EGFR kinase activity, in a dose-dependent manner, while lyso-GM3 trimer and tetramer did not. >50 μM lyso-GM3 was cytolytic, while >50 μM lyso-GM3 dimer was not cytolytic, yet inhibited EGFR kinase strongly. Thus, lyso-GM3 and its dimer exert an auxiliary effect on GM3-induced inhibition of EGFR kinase and cell growth, and lyso-GM3 dimer may be a good candidate for pharmacological inhibitor of epidermal tumor growth.
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binding of rainbow trout sperm to egg is mediated by strong carbohydrate to carbohydrate interaction between kdn GM3 deaminated neuraminyl ganglioside and gg3 like epitope
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Naoya Kojima, Senitiroh Hakomori, Shigeharu Kudo, Sadako Inoue, Yasuo InoueAbstract:KDNα2→3Galβ4Glcβ1Cer [(KDN)GM3] is a major (≈90%) component of total gangliosides found in sperm of rainbow trout (Oncorhynchus mykiss) and was shown to be present prominently at the sperm head by immunochemical staining with its specific mAb kdn3G. Liposomes containing (KDN)GM3 adhere specifically to GalNAcβ4Galβ4Glcβ1Cer (Gg3Cer)-coated plastic plates. Interaction between (KDN)GM3 and Gg3Cer was much stronger than that previously observed between Neu5Acα2→3Galβ4Glcβ1Cer and Gg3Cer. (KDN)GM3–Gg3Cer interaction did not require the presence of Ca2+ and Mg2+, but was enhanced in the presence of Mn2+. Fresh trout sperm adhered specifically to Gg3Cer-coated plates under physiological conditions, and the binding was inhibited by pretreatment of sperm with mAb kdn3G. The presence of Gg3 or Gg3-related epitope structure in the specific area surrounding the micropyle, through which sperm enter the egg, was confirmed by immunogold labeling under electron microscopy. These findings suggest that initial sperm-egg adhesion during the process of fertilization occurs when sperm adhere to the area surrounding the micropyle through specific interaction between (KDN)GM3 on the sperm head and Gg3 epitope (GalNAcβ4Galβ1→) expressed at a defined region of the egg surface membrane.
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GM3 ganglioside inhibits CD9-facilitated haptotactic cell motility: coexpression of GM3 and CD9 is essential in the downregulation of tumor cell motility and malignancy.
Biochemistry, 2001Co-Authors: Masaya Ono, Kazuko Handa, Donald A. Withers, Sandro Sonnino, Hideo Nagai, Senitiroh HakomoriAbstract:A cooperative inhibitory effect of GM3, together with CD9, on haptotactic cell motility was demonstrated by a few lines of study as described below. (i) Haptotactic motility of colorectal carcinoma cell lines SW480, SW620, and HRT18, which express CD9 at a high level, is inhibited by exogenous GM3, but not by GM1. (ii) Motility of gastric cancer cell line MKN74, which expresses CD9 at a low level, was not affected by exogenous GM3. Its motility became susceptible to and inhibited by exogenous GM3, but not GM1, when the CD9 level of MKN74 cells was converted to a high level by transfection with CD9 cDNA. Findings i and ii suggest that haptotactic tumor cell motility is cooperatively inhibited by coexpression of CD9 and GM3. (iii) This possibility was further demonstrated using cell line ldlD 14, and its derivative expressing CD9 through transfection of its gene (termed ldlD/CD9). Both of these cell lines are defective in UDP-Gal 4-epimerase and cannot synthesize GM3 unless cultured in the presence of galac...
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Reconstitution of membranes simulating "glycosignaling domain" and their susceptibility to lyso-GM3.
The Journal of biological chemistry, 2000Co-Authors: Kazuhisa Iwabuchi, Kazuko Handa, Yongmin Zhang, Donald A. Withers, Pierre Sinaÿ, Senitiroh HakomoriAbstract:GM3 ganglioside at the surface of mouse melanoma B16 cells is clustered and organized with signal transducer molecules c-Src, Rho A, and focal adhesion kinase (FAK) to form a membrane unit separable from caveolae, which are enriched in cholesterol and caveolin but do not contain GM3 or the above three signal transducers. The GM3-enriched membrane units are involved in GM3-dependent cell adhesion coupled with activation of c-Src, Rho A, and FAK and are termed the "glycosphingolipid signaling domain" or the "glycosignaling domain" (GSD). In order to assess the essential components that display GSD function, membranes with properties similar to those of GSD were reconstituted using GM3, sphingomyelin, and c-Src, with or without other lipid components. The reconstituted membrane thus prepared displayed GM3-dependent adhesion to plates coated with Gg3 or anti-GM3 antibody, resulting in enhanced c-Src phosphorylation (c-Src phosphorylation response). This response in reconstituted membrane depends on GM3 concentration and was not observed when GM3 was absent or replaced with other gangliosides GM1 or GD1a, or with LacCer. The GM3-dependent c-Src phosphorylation response was enhanced when cholesterol and phosphatidylcholine were added. Although GM3, sphingomyelin, and c-Src are essential for GSD function, a small quantity of cholesterol and phosphatidylcholine may act as an auxiliary factor to stabilize membrane. GSD function in terms of GM3-dependent adhesion and signaling was blocked in the presence of lyso-GM3 or its analogue but not psychosine, lactosyl-sphingosine, or lyso-phosphatidylcholine. Such susceptibility of reconstituted GSD to lyso-GM3 and other lyso compounds is the same as GSD of original B16 cells. Thus, functional organization of the reconstituted membrane closely simulates that of GSD in B16 cells, which is based on clustered GM3 organized with c-Src as the essential components.
Cheorl-ho Kim - One of the best experts on this subject based on the ideXlab platform.
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GM3 Protects Cochlear Hair Cells and Hearing from Corti Degeneration
GM3 Signaling, 2020Co-Authors: Cheorl-ho KimAbstract:Deficiency of GM3 synthase leads to deficits in newborn hearing and auditory in humans. For example, deficiency of GM3 synthase causes severe neuronal diseases, showing deafness and neurological disability. The auditory function is characterized by stereocilia of outer hair cells. GM3-associated membrane microdomain of lipid raft formation is crucial for the relevant organization stereocilia in auditory hair cells [1]. GM3 is the dominant cochlear GSL. In postnatal periods, GM3 level is increased with GlcCer, sulatides of SM3 and SM4, GM1, GD1a, GD3, GD1b, and GT1b. GM3 is required for both the neural sound and cochlear editing in vertebrates, especially mammals. In the GM3 synthase, SAT-I KO mice, the hearing attitude was almost completely impaired with spatial stereocilia damage and degeneration of hair cells resided in the Corti organ [2]. The close relation between hearing ability and local ganglioside synthesis is suggested, but the ganglioside’s action and function are still unknown in their roles. The GM3 defection in mice, which are null in GM3 synthase SAT-I gene, caused hearing ability, impairing the development of hearing, and hearing was almost disappeared by 17 days after birth without hair cell formity in the Corti organ [3]. Causing factor of the defected hearing capacity of SAT-I-KO mice was attributed to the absence of GM3 product. GM3 is important during the cochlea development and maturation for the hearing acquisition and maintenance. Ganglioside roles for formation of lipid raft microdomains in auditory systems are developmentally important issue. Cochlea is an auditory organ, receiving the sound in inner ear. Many different gangliosides were expressed in the region of Corti, tectorial membrane, stria vascularis, Reissner’s membrane, and spiral ganglion of the cochlea. Especially, polysialic acid and GM3 were highly expressed in spiral ganglion region. Ganglioside GM3 recovers from hearing dysfunctional region due to selective regeneration of the Corti organ. The gangliosides of a/b/c series are modified to o series such as GD1 and GM1b. However, GM3 synthase KO mice are phenotypically characteristic for hearing defect or loss because of selectively targeted degenerative event in the Corti organ. When normal mouse produces different species of gangliosides including GM1, GM3, GT1b, GD1b, and GD1a, the GM3 KO mice produce only GM1b and GD1α. Thus, GM3 loss is a causing factor for the primary degeneration of the Corti organ. Thus, other factors such as metabolic changes in the endolymph, where Cochlea maturation requires the ganglioside for the hearing ability, are not considered. Then how GM3 works for the Cochlea maturation? Spatially produced GMs are important with temporal production for the formation and organization of the normal function and structure of auditory hair cells. From the results obtained in the GM3 synthase KO mice, it is mentioned that the auditory hearing loss is clearly caused by GM3 deficiency due to its lack of the synthetic enzyme, but the GM3-related conclusion does not always fully explain the complete mechanism. Interestingly, GM3-deficient mice showed some dysfunctional phenotypes including the interference with cerebral neuron myelination and electrical plasticity. Then, another possibility of the GM3-associated lipid raft microdomain has been raised to explain the mechanistic action of GM3. The role of lipid raft microdomain embedded with GM3 is linked in the CNS development and its functional maintenance. As hearing attitude levels are reduced at human birth due to mutations of GM3 synthase gene, in the experimental animal, the St3gal5−/− mice showed the similar mode to the animal phenotype. However, the hair cell remodeling and functional degeneration of the St3gal5−/− mice can be regenerated and reformed by ganglioside repletion therapy.
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Synthesis of GM3
GM3 Signaling, 2020Co-Authors: Cheorl-ho KimAbstract:Sialic acid (SA) is a 9-carbon sugar in eukaryotic cells. SA metabolism and catabolism are cooperatively linked in the cells. The SA transfer, modification, catabolic reactions, biosynthesis, and activation in extracellular region, plasma membrane, cytosol, endoplasmic reticulum, Golgi apparatus, and nucleus are simply described (Fig. 2.1). GM3 is a staring ganglioside during biosynthesis for serial gangliosides including a-, b- and c-series (Fig. 2.2). Ganglioside species are predominantly present in the extracellular and outer side of cellular membrane leaflets and recognize cellular plasma membrane (PM) proteins through basically non-covalent electrostatic and hydrophobic interactions. Consequently, they form microdomains or lipid rafts. GM3 is enzymatically biosynthesized by GM3 synthase enzyme, CMP-N-acetylneuraminic acid/lactosyl-Cer α2,3N-acetylneuraminyltransferase (EC 2.4.99.9) or SAT-I and ST3Gal V (Fig. 2.3). Ganglioside GM3 and GD3 structures are shown in Fig. 2.4.
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GM3 as a Pathogenic Infection Receptor
GM3 Signaling, 2020Co-Authors: Cheorl-ho KimAbstract:The fact that the GM3 or related gangliosides are localized on cell surfaces allows the possibility that the extracellular interaction of pathogenic agents such as bacteria and viruses is mediated via those gangliosides. Glycans of gangliosides are recognized with high affinity and specificity by infectious protein factors. GSLs frequently act as recognition and interaction sites for pathogenic bacteria and parasites as well as infectious viruses. Therefore, the GSLs are the entry sites for invaders [1]. The gangliosides function as mediators in viral fusion. For example, the glycan moieties can be interacted with glycoproteins or other carbohydrates expressed on their own cellular PM in the same cells or in the neighbored surrounding cells. For example, with regard to the simian rotavirus receptors, infection of host cells with the simian rotavirus SA11 strain is inhibited by neuraminidase, and the result indicates the involvement of SA-linked receptors present in the cell surfaces of host [2]. Host infection with rotavirus strain SA11 was also blocked by treatments with sialylated glycoproteins [3] and by the GM1 ganglioside [4]. Rotavirus strain SA11 binds to the nonacid GSL gangliotetraosylceramid GA1 or another name of asialo-GM1, but not other gangliosides. GM3 in a form of either N-glycolylneuraminic acid (NeuGc) or N-acetylneuraminic acid (NeuAc) is recognized to be the cell surface receptors for attachment and infection of the porcine rotavirus strains [5, 6]. Another type of GM1a similarly mediates a certain rotaviral infection by the newly classified rotavirus strain, a neuraminidase-insensitive human rotavirus [7]. Representatively, GM3 functions as a receptor of bovine rotavirus [8], human immunodeficiency virus (HIV) [9], and simian rotavirus [8]. HIV-2 and HIV-1 glycoproteins are recognized by GM3, and GM3 is the abundantly expressed ganglioside, in the CD4(+) lymphocytes PM and macrophages PM. Adsorption and attachment of HIVs to the target cell surfaces require a recognition and binding of the envelope glycoprotein present on cell surface and certain cell types of GalCer, which is recognized by CD4(−) cells and GM3 by CD4(+) cells for their molecular interactions. The cellular binding sites for HIV antigens on CD4+ lymphocytes are GM3 [10]. GM3 represents HIV-1 gp120-binding sites on the CD4+ cell surfaces. Ganglioside-binding motif of the gp120 protein on the host cell surfaces is reported to be XXXGPGRAFXXX [11–13]. The gp120 motif homologous sites are also observed in synucleins, galectins, transmembrane receptors, and TNF-a receptor superfamily [14, 15].
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GM3, Caveolin-1 and Insulin Receptor in Insulin Resistance
GM3 Signaling, 2020Co-Authors: Cheorl-ho KimAbstract:GM3 ganglioside involves various cellular events of receptor-associated signalings. GM3 regulates signaling pathway involved in the insulin resistance and diabetes process. The GM3 contents generated by the ST enzyme ST3Gal V/GM3 synthase/SAT-I are upregulated in the adipose, kidney, liver, and murine muscles of animal diabetes [1]. The aberrant expression of GM3 in adipose tissue accelerates diabetic development and progression, especially in the type 2 diabetic mellitus (T2DM) and insulin resistance known for metabolic disorders. Increased GM3 level is found in the plasma fluids of T2DM, vasculopathies and microvascular lesions [2]. The GM3 synthase gene is upregulated in the T2DM patients with kidney pathies and nephropathies [3]. TNF-α is known to cause insulin resistance and increase GM3 synthase gene expression as well as GM3 product in insulin-interacting receiver cells such as hepatocytes, adipocytes, and myocytes. The obesity and diabetic role of GM3 has been attributed to impaired insulin action [4]. In human studies, aberrantly increased serum level of GM3 is detected in hyperglycemic, hyperlipidemic, and T2DM patients [5, 6]. Glucocerebrosidase deficient Gaucher disease shows insulin resistance with serum GM3 level [7]. Therefore, aberrant GM3 synthesis and its metabolic reutilization may contribute to defection of glucose and lipid metabolic homeostasis. Therefore, better understanding of the fundamental mechanism will open the way to potential therapies using targeting GM3.
Nouara Yahi - One of the best experts on this subject based on the ideXlab platform.
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Molecular Basis for the Glycosphingolipid-Binding Specificity of alpha-Synuclein: Key Role of Tyrosine 39 in Membrane Insertion
Journal of Molecular Biology, 2011Co-Authors: Jacques Fantini, Nouara YahiAbstract:Cell surface glycosphingolipids (GSLs) including gangliosides play a key role in the regulation of the conformation, oligomerization, and fibrillation of amyloidogenic proteins. Correspondingly, most amyloidogenic proteins possess a functional GSL-binding motif (GBM). Sequence alignments of GSL-binding proteins against the GBM of alpha-synuclein allowed the establishment of a consensus GBM sequence defined as K/H/R/-X(1-4)-Y/F-X(4-5)-K/H/R, where at least one of the X(1-4) residues is glycine. The GBMs of alpha-synuclein (34-KEGVLYVGSKTK-45) and Alzheimer's disease beta-amyloid peptide (A beta) (5-RHDSGYEVHHQK-16) consist of a structurally related loop centered on tyrosine (Y39 for alpha-synuclein, Y10 for A beta). Surface pressure measurements of GSL monolayers at the air water interface allowed us to determine the following order for alpha-synuclein GSL interactions: GM3 > Gb3 > GalCer-NFA > GM1 > sulfatide > GalCer-HFA > LacCer > GM4 > GM2 > asialo-GM1 > GD3, indicating a marked preference for GSLs with one, three, or five sugar units. The insertion of alpha-synuclein into sphingomyelin-containing monolayers was strongly stimulated by the presence of GM3. This effect was not observed with phosphatidylcholine monolayers, suggesting that the ganglioside facilitated the insertion of alpha-synuclein into raft-like membrane domains. Molecular dynamics simulations suggested that the side chain of Y39 was deeply inserted between GM3 head groups. Monolayer experiments with mutant GBM peptides showed that Y39, K34, and K45 were important for GM3 binding, whereas only Y39 appeared critical for GM1 recognition. The interaction of A beta 5-16 with GM1 involved R5, H13, H14, and K16, but not Y10. These data indicate that subtle amino acid variations in the consensus GBM of alpha-synuclein and A beta conferred distinct GSL-binding properties. (C) 2011 Elsevier Ltd. All rights reserved.
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Altered ion channel formation by the Parkinson's-disease-linked E46K mutant of alpha-synuclein is corrected by GM3 but not by GM1 gangliosides.
Journal of Molecular Biology, 2010Co-Authors: Eric Di Pasquale, Jacques Fantini, Marc Maresca, Henri Chahinian, Nadira Taïeb, Nouara YahiAbstract:Alpha-synuclein (alpha-syn) is an amyloidogenic protein that plays a key role in the pathogenesis of Parkinson's disease (PD). The ability of alpha-syn oligomers to form ionic channels is postulated as a channelopathy mechanism in human brain. Here we identified a ganglioside-binding domain in alpha-syn (fragment 34-50), which includes the mutation site 46 linked to a familial form of PD (E46K). We show that this fragment is structurally related to the common glycosphingolipid-binding domain (GBD) shared by various microbial and amyloid proteins, including Alzheimer's beta-amyloid peptide. alpha-Syn GBD interacts with several glycosphingolipids but has a marked preference for GM3, a minor brain ganglioside whose expression increases with aging. The alpha-syn mutant E46K has a stronger affinity for GM3 than the wild-type protein, and the interaction is inhibited by 3'-sialyllactose (the glycone part of GM3). Alanine substitutions of Lys34 and Tyr39 in synthetic GBD peptides resulted in limited interaction with GM3, demonstrating the critical role of these residues in GM3 recognition. When incubated with reconstituted phosphatidylcholine bilayers, the E46K protein formed channels that are five times less conductive than those formed by wild-type alpha-syn, exhibit a higher selectivity for cations, and present an asymmetrical response to voltage and nonstop single-channel activity. This E46K-associated channelopathy was no longer observed when GM3 was present in phosphatidylcholine bilayers. This corrective effect was highly specific for GM3, since it was not obtained with the major brain ganglioside GM1 but was still detected in bilayer membranes containing both GM3 and GM1. Moreover, synthetic GBD peptides prevented the interaction of alpha-syn proteins with GM3, thus abolishing the regulatory effects of GM3 on alpha-syn-mediated channel formation. Overall, these data show that GM3 can specifically regulate alpha-syn-induced channel formation and raise the intriguing possibility that this minor brain ganglioside could play a key protective role in the pathogenesis of PD.
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altered ion channel formation by the parkinson s disease linked e46k mutant of α synuclein is corrected by GM3 but not by gm1 gangliosides
Journal of Molecular Biology, 2010Co-Authors: Eric Di Pasquale, Jacques Fantini, Marc Maresca, Henri Chahinian, Nadira Taïeb, Nouara YahiAbstract:Abstract α-Synuclein (α-syn) is an amyloidogenic protein that plays a key role in the pathogenesis of Parkinson's disease (PD). The ability of α-syn oligomers to form ionic channels is postulated as a channelopathy mechanism in human brain. Here we identified a ganglioside-binding domain in α-syn (fragment 34–50), which includes the mutation site 46 linked to a familial form of PD (E46K). We show that this fragment is structurally related to the common glycosphingolipid-binding domain (GBD) shared by various microbial and amyloid proteins, including Alzheimer's β-amyloid peptide. α-Syn GBD interacts with several glycosphingolipids but has a marked preference for GM3, a minor brain ganglioside whose expression increases with aging. The α-syn mutant E46K has a stronger affinity for GM3 than the wild-type protein, and the interaction is inhibited by 3′-sialyllactose (the glycone part of GM3). Alanine substitutions of Lys34 and Tyr39 in synthetic GBD peptides resulted in limited interaction with GM3, demonstrating the critical role of these residues in GM3 recognition. When incubated with reconstituted phosphatidylcholine bilayers, the E46K protein formed channels that are five times less conductive than those formed by wild-type α-syn, exhibit a higher selectivity for cations, and present an asymmetrical response to voltage and nonstop single-channel activity. This E46K-associated channelopathy was no longer observed when GM3 was present in phosphatidylcholine bilayers. This corrective effect was highly specific for GM3, since it was not obtained with the major brain ganglioside GM1 but was still detected in bilayer membranes containing both GM3 and GM1. Moreover, synthetic GBD peptides prevented the interaction of α-syn proteins with GM3, thus abolishing the regulatory effects of GM3 on α-syn-mediated channel formation. Overall, these data show that GM3 can specifically regulate α-syn-induced channel formation and raise the intriguing possibility that this minor brain ganglioside could play a key protective role in the pathogenesis of PD.
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human erythrocyte glycosphingolipids as alternative cofactors for human immunodeficiency virus type 1 hiv 1 entry evidence for cd4 induced interactions between hiv 1 gp120 and reconstituted membrane microdomains of glycosphingolipids gb3 and GM3
Journal of Virology, 1999Co-Authors: Djilali Hammache, Nouara Yahi, Marc Maresca, Gerard Pieroni, Jacques FantiniAbstract:Glycosphingolipids from human erythrocytes mediate CD4-dependent fusion with cells expressing human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins. To identify the glycosphingolipid(s) which participates in the fusion process, we have analyzed the interaction of HIV-1 gp120 (X4 and R5X4 isolates) with reconstituted membrane microdomains of human erythrocyte glycosphingolipids. We identified globotriaosylceramide (Gb3) and ganglioside GM3 as the main glycosphingolipids recognized by gp120. In the presence of CD4, Gb3 interacted preferentially with the X4 gp120, whereas GM3 interacted exclusively with the R5X4 gp120. These data suggest that glycosphingolipid microdomains are required in CD4-dependent fusion and that Gb3 and/or GM3 may function as alternative entry cofactors for selected HIV-1 isolates.
Vincent Procaccio - One of the best experts on this subject based on the ideXlab platform.
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Refractory epilepsy and mitochondrial dysfunction due to GM3 synthase deficiency
European Journal of Human Genetics, 2013Co-Authors: Konstantina Fragaki, Samira Ait-el-mkadem, Annabelle Chaussenot, Catherine Gire, Raymond Mengual, Laurent Bonesso, Marie Bénéteau, Jean-ehrland Ricci, Valérie Desquiret-dumas, Vincent ProcaccioAbstract:We report two children, born from consanguineous parents, who presented with early-onset refractory epilepsy associated with psychomotor delay, failure to thrive, blindness and deafness. Polarographic and spectrophotometric analyses in fibroblasts and liver revealed a respiratory chain (RC) dysfunction. Surprisingly, we identified a homozygous nonsense mutation in the GM3 synthase gene by using exome sequencing. GM3 synthase catalyzes the formation of GM3 ganglioside from lactosylceramide, which is the first step in the synthesis of complex ganglioside species. Mass spectrometry analysis revealed that the complete absence of GM3 ganglioside and its biosynthetic derivatives was associated with an upregulation of the alternative globoside pathway in fibroblasts. The accumulation of Gb3 and Gb4 globosides likely has a role in RC dysfunction and in the decrease of mitochondrial membrane potential leading to apoptosis, which we observed in fibroblasts. We show for the first time that GM3 synthase deficiency, responsible for early-onset epilepsy syndrome, leads to a secondary RC dysfunction. Our study highlights the role of secondary mitochondrial disorders that can interfere with the diagnosis and the evolution of other metabolic diseases.
Jacques Fantini - One of the best experts on this subject based on the ideXlab platform.
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Molecular Basis for the Glycosphingolipid-Binding Specificity of alpha-Synuclein: Key Role of Tyrosine 39 in Membrane Insertion
Journal of Molecular Biology, 2011Co-Authors: Jacques Fantini, Nouara YahiAbstract:Cell surface glycosphingolipids (GSLs) including gangliosides play a key role in the regulation of the conformation, oligomerization, and fibrillation of amyloidogenic proteins. Correspondingly, most amyloidogenic proteins possess a functional GSL-binding motif (GBM). Sequence alignments of GSL-binding proteins against the GBM of alpha-synuclein allowed the establishment of a consensus GBM sequence defined as K/H/R/-X(1-4)-Y/F-X(4-5)-K/H/R, where at least one of the X(1-4) residues is glycine. The GBMs of alpha-synuclein (34-KEGVLYVGSKTK-45) and Alzheimer's disease beta-amyloid peptide (A beta) (5-RHDSGYEVHHQK-16) consist of a structurally related loop centered on tyrosine (Y39 for alpha-synuclein, Y10 for A beta). Surface pressure measurements of GSL monolayers at the air water interface allowed us to determine the following order for alpha-synuclein GSL interactions: GM3 > Gb3 > GalCer-NFA > GM1 > sulfatide > GalCer-HFA > LacCer > GM4 > GM2 > asialo-GM1 > GD3, indicating a marked preference for GSLs with one, three, or five sugar units. The insertion of alpha-synuclein into sphingomyelin-containing monolayers was strongly stimulated by the presence of GM3. This effect was not observed with phosphatidylcholine monolayers, suggesting that the ganglioside facilitated the insertion of alpha-synuclein into raft-like membrane domains. Molecular dynamics simulations suggested that the side chain of Y39 was deeply inserted between GM3 head groups. Monolayer experiments with mutant GBM peptides showed that Y39, K34, and K45 were important for GM3 binding, whereas only Y39 appeared critical for GM1 recognition. The interaction of A beta 5-16 with GM1 involved R5, H13, H14, and K16, but not Y10. These data indicate that subtle amino acid variations in the consensus GBM of alpha-synuclein and A beta conferred distinct GSL-binding properties. (C) 2011 Elsevier Ltd. All rights reserved.
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Altered ion channel formation by the Parkinson's-disease-linked E46K mutant of alpha-synuclein is corrected by GM3 but not by GM1 gangliosides.
Journal of Molecular Biology, 2010Co-Authors: Eric Di Pasquale, Jacques Fantini, Marc Maresca, Henri Chahinian, Nadira Taïeb, Nouara YahiAbstract:Alpha-synuclein (alpha-syn) is an amyloidogenic protein that plays a key role in the pathogenesis of Parkinson's disease (PD). The ability of alpha-syn oligomers to form ionic channels is postulated as a channelopathy mechanism in human brain. Here we identified a ganglioside-binding domain in alpha-syn (fragment 34-50), which includes the mutation site 46 linked to a familial form of PD (E46K). We show that this fragment is structurally related to the common glycosphingolipid-binding domain (GBD) shared by various microbial and amyloid proteins, including Alzheimer's beta-amyloid peptide. alpha-Syn GBD interacts with several glycosphingolipids but has a marked preference for GM3, a minor brain ganglioside whose expression increases with aging. The alpha-syn mutant E46K has a stronger affinity for GM3 than the wild-type protein, and the interaction is inhibited by 3'-sialyllactose (the glycone part of GM3). Alanine substitutions of Lys34 and Tyr39 in synthetic GBD peptides resulted in limited interaction with GM3, demonstrating the critical role of these residues in GM3 recognition. When incubated with reconstituted phosphatidylcholine bilayers, the E46K protein formed channels that are five times less conductive than those formed by wild-type alpha-syn, exhibit a higher selectivity for cations, and present an asymmetrical response to voltage and nonstop single-channel activity. This E46K-associated channelopathy was no longer observed when GM3 was present in phosphatidylcholine bilayers. This corrective effect was highly specific for GM3, since it was not obtained with the major brain ganglioside GM1 but was still detected in bilayer membranes containing both GM3 and GM1. Moreover, synthetic GBD peptides prevented the interaction of alpha-syn proteins with GM3, thus abolishing the regulatory effects of GM3 on alpha-syn-mediated channel formation. Overall, these data show that GM3 can specifically regulate alpha-syn-induced channel formation and raise the intriguing possibility that this minor brain ganglioside could play a key protective role in the pathogenesis of PD.
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altered ion channel formation by the parkinson s disease linked e46k mutant of α synuclein is corrected by GM3 but not by gm1 gangliosides
Journal of Molecular Biology, 2010Co-Authors: Eric Di Pasquale, Jacques Fantini, Marc Maresca, Henri Chahinian, Nadira Taïeb, Nouara YahiAbstract:Abstract α-Synuclein (α-syn) is an amyloidogenic protein that plays a key role in the pathogenesis of Parkinson's disease (PD). The ability of α-syn oligomers to form ionic channels is postulated as a channelopathy mechanism in human brain. Here we identified a ganglioside-binding domain in α-syn (fragment 34–50), which includes the mutation site 46 linked to a familial form of PD (E46K). We show that this fragment is structurally related to the common glycosphingolipid-binding domain (GBD) shared by various microbial and amyloid proteins, including Alzheimer's β-amyloid peptide. α-Syn GBD interacts with several glycosphingolipids but has a marked preference for GM3, a minor brain ganglioside whose expression increases with aging. The α-syn mutant E46K has a stronger affinity for GM3 than the wild-type protein, and the interaction is inhibited by 3′-sialyllactose (the glycone part of GM3). Alanine substitutions of Lys34 and Tyr39 in synthetic GBD peptides resulted in limited interaction with GM3, demonstrating the critical role of these residues in GM3 recognition. When incubated with reconstituted phosphatidylcholine bilayers, the E46K protein formed channels that are five times less conductive than those formed by wild-type α-syn, exhibit a higher selectivity for cations, and present an asymmetrical response to voltage and nonstop single-channel activity. This E46K-associated channelopathy was no longer observed when GM3 was present in phosphatidylcholine bilayers. This corrective effect was highly specific for GM3, since it was not obtained with the major brain ganglioside GM1 but was still detected in bilayer membranes containing both GM3 and GM1. Moreover, synthetic GBD peptides prevented the interaction of α-syn proteins with GM3, thus abolishing the regulatory effects of GM3 on α-syn-mediated channel formation. Overall, these data show that GM3 can specifically regulate α-syn-induced channel formation and raise the intriguing possibility that this minor brain ganglioside could play a key protective role in the pathogenesis of PD.
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human erythrocyte glycosphingolipids as alternative cofactors for human immunodeficiency virus type 1 hiv 1 entry evidence for cd4 induced interactions between hiv 1 gp120 and reconstituted membrane microdomains of glycosphingolipids gb3 and GM3
Journal of Virology, 1999Co-Authors: Djilali Hammache, Nouara Yahi, Marc Maresca, Gerard Pieroni, Jacques FantiniAbstract:Glycosphingolipids from human erythrocytes mediate CD4-dependent fusion with cells expressing human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins. To identify the glycosphingolipid(s) which participates in the fusion process, we have analyzed the interaction of HIV-1 gp120 (X4 and R5X4 isolates) with reconstituted membrane microdomains of human erythrocyte glycosphingolipids. We identified globotriaosylceramide (Gb3) and ganglioside GM3 as the main glycosphingolipids recognized by gp120. In the presence of CD4, Gb3 interacted preferentially with the X4 gp120, whereas GM3 interacted exclusively with the R5X4 gp120. These data suggest that glycosphingolipid microdomains are required in CD4-dependent fusion and that Gb3 and/or GM3 may function as alternative entry cofactors for selected HIV-1 isolates.