Ganglioside GM1 Research Articles

SARS-CoV-2 Binding to Terminal Sialic Acid of Gangliosides Embedded in Lipid Membranes.

Multiple recent reports indicate that the S protein of SARS-CoV-2 specifically interacts with membrane receptors and attachment factors other than ACE2. They likely have an active role in cellular attachment and entry of the virus. In this article, we examined the binding of SARS-CoV-2 particles to gangliosides embedded in supported lipid bilayers (SLBs), mimicking the cell membrane-like environment. We show that the virus specifically binds to sialylated (sialic acid (SIA)) gangliosides, i.e., GD1a, GM3, and GM1, as determined from the acquired single-particle fluorescence images using a time-lapse total internal reflection fluorescence (TIRF) microscope. The data of virus binding events, the apparent binding rate constant, and the maximum virus coverage on the ganglioside-rich SLBs show that the virus particles have a higher binding affinity toward the GD1a and GM3 compared to the GM1 ganglioside. Enzymatic hydrolysis of the SIA-Gal bond of the gangliosides confirms that the SIA sugar unit of GD1a and GM3 is essential for virus attachment to the SLBs and even the cell surface sialic acid is critical for the cellular attachment of the virus. The structural difference between GM3/GD1a and GM1 is the presence of SIA at the main or branched chain. We conclude that the number of SIA per ganglioside can weakly influence the initial binding rate of SARS-CoV-2 particles, whereas the terminal or more exposed SIA is critical for the virus binding to the gangliosides in SLBs.

Complement Turning Violent in Ultra-Rare Genetic Disorder

Abstract Sandhoff disease (SD) is an ultra-rare lysosomal storage disorder (LSD), which affects ~ 1/1000, 000 live birth. SD is caused by genetic deficiency of beta (β) Hexosaminidase and resulting excess central nervous system (CNS) synthesis of GM2 ganglioside (GM2) and its impact on neuron death. The exact mechanisms underlying such GM2-driven neuron death are unknown in SD. Glucosylceramide (GC) induced complement 5a (C5a) and its C5aR1 activation causes tissue inflammation in experimental and clinical Gaucher disease. Additionally, C5a-C5aR1 axis was found to sparks CNS inflammation and neurodegeneration in several brain diseases including, intracerebral hemorrhage, traumatic brain injury, myasthenia gravis, amyotrophic lateral sclerosis, neuromyelitis optica spectrum, Alzheimer, and Huntington’s diseases. Here, we determined the increased brain levels of C5a and C5aR1 in a beta (β) hexosaminidase inhibitor (HABI)-induced experimental mouse model of SD, when compared to vehicle (PBS) injected WT control mice. Also, HABI-induced experimental mouse model of SD showed increased microglial cells activation, massive brain generation of pro-inflammatory cytokines and loss of neurons, when compared to vehicle injected WT mice. To assess the relevance of C5a-C5aR1 axis activation for brain inflammation in SD, we targeted β hexosaminidase with HAB-I in WT and C5aR1 −/−mice. Strikingly, as compared to HABI-injected WT mice, HABI-injected C5aR1 −/−mice caused marked reduction in microglial cell activation, brain production of pro-inflammatory cytokines, and the loss of neurons. These data suggest that the C5a-C5aR1 axis is a critical driver of neuroinflammation and neurodegeneration in SD. No Funding

A platelet lipidomics signature in patients with COVID-19

Ischemic cardiovascular and venous thromboembolic events are a frequent cause of death in severe COVID-19 patients. Platelet activation plays a key role in these complications, however platelet lipidomics have not been studied yet. The aim of our pilot investigation was to perform a preliminary study of platelet lipidomics in COVID-19 patients compared to healthy subjects. Lipid extraction and identification of ultrapurified platelets from eight hospitalized COVID-19 patients and eight age- and sex-matched healthy controls showed a lipidomic pattern almost completely separating COVID-19 patients from healthy controls. In particular, a significant decrease of ether phospholipids and increased levels of ganglioside GM3 were observed in platelets from COVID-19 patients. In conclusion, our study shows for the first time that platelets from COVID-19 patients display a different lipidomics signature distinguishing them from healthy controls, and suggests that altered platelet lipid metabolism may play a role in viral spreading and in the thrombotic complications of COVID-19.

Dynamic assembly and interaction of glycosphingolipids in cholesterol-containing model membranes

Abstract Glycosphingolipids (GSLs) in the mammalian plasma membrane are essential for various biological events that occur on cell membranes by forming glycolipid-rich membrane domains, such as lipid rafts. Lactosylceramide (LacCer) forms a highly ordered phase in model and biological membranes. However, the details of this domain remain unclear. We examined the dynamic assembly of LacCer in cholesterol-containing phase-separated membranes by fluorescence imaging and solid-state NMR. Solid-state 2H NMR of the deuterated LacCer probes in the membranes indicated that the potent LacCer–LacCer interaction significantly reduced the incorporation of cholesterol in the LacCer domains. Moreover, increasing the amount of cholesterol induced the formation of nanometer-scale LacCer domains, which can be biologically relevant. The lateral interaction of ganglioside GM3 with the epidermal growth factor receptor (EGFR) transmembrane segment was examined using fluorescence spectroscopy under membrane conditions. Lateral FRET between the NBD fluorophore on the EGFR transmembrane segment and the ATTO594 fluorophore on the GM3 head group suggested that GM3 interacts with the transmembrane segment and partially inhibits the EGFR dimerization by stabilizing the peptide monomer. More precise investigations of GSL–GSL and GSL-protein interactions occurring in membrane environments can lead to the elucidation of the cellular functions of GSL from structural points of view.

GM1 Oligosaccharide Efficacy in Parkinson's Disease: Protection against MPTP.

Past evidence has shown that the exogenous administration of GM1 ganglioside slowed neuronal death in preclinical models of Parkinson's disease, a neurodegenerative disorder characterized by the progressive loss of dopamine-producing neurons: however, the physical and chemical properties of GM1 (i.e., amphiphilicity) limited its clinical application, as the crossing of the blood-brain barrier is denied. Recently, we demonstrated that the GM1 oligosaccharide head group (GM1-OS) is the GM1 bioactive portion that, interacting with the TrkA-NGF complex at the membrane surface, promotes the activation of a multivariate network of intracellular events regulating neuronal differentiation, protection, and reparation. Here, we evaluated the GM1-OS neuroprotective potential against the Parkinson's disease-linked neurotoxin MPTP, which destroys dopaminergic neurons by affecting mitochondrial bioenergetics and causing ROS overproduction. In dopaminergic and glutamatergic primary cultures, GM1-OS administration significantly increased neuronal survival, preserved neurite network, and reduced mitochondrial ROS production enhancing the mTOR/Akt/GSK3β pathway. These data highlight the neuroprotective efficacy of GM1-OS in parkinsonian models through the implementation of mitochondrial function and reduction in oxidative stress.

GM1 Reduced the Symptoms of Autism Spectrum Disorder by Suppressing α-Syn Through Activating Autophagy

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that cannot be cured. The ASD rat model was developed in this study to demonstrate the role and mechanism of ganglioside GM1 (GM1). Rats were given valproic acid (VPA) to create the ASD rat model. The rats' behaviors were assessed using the Y-maze test, open-field test, three-chamber social interaction test, and Morris water maze test. Relative levels of glutathione (GSH), malondialdehyde (MDA), catalase (CAT), reactive oxygen species (ROS), and superoxide dismutase (SOD) were quantitated using relative kits. Nissl, TUNEL, immunofluorescent, and immunohistochemistry staining techniques were used. GM1 treatment improved the ASD model rats' behavior disorders, including locomotor activity and exploratory behavior, social interaction, learning and memory capacity, and repetitive behavior. Following GM1 injection, striatal neurons grew and apoptosis decreased. GM1 reduced the excessively elevated α-Syn in ASD by encouraging autophagy. The behavior disorder of ASD model rats was exacerbated by autophagy inhibition, which also increased α-Syn levels. By increasing autophagy, GM1 reduced α-Syn levels and, ultimately, improved behavioral abnormalities in ASD model rats.

Cytotoxic effects of recombinant proteins enhanced by momordin Ic are dependent on cholesterol and ganglioside GM1

Plant-derived triterpenoid saponins have been shown to play a powerful role in enhancing the cytotoxic activity of protein therapeutics. However, the mechanism of how saponins are acting is not clearly understood. In this study, momordin Ic (MIC), a triterpenoid saponin derived from Kochia scoparia (L.) Schrad., specifically enhance the antiproliferative effect of recombinant MAP30 (a type I ribosome inactivating protein, RIP) in breast cancer cells. Subsequently, the possible mechanism of how MIC enhanced the cytotoxicity of MAP30 was analyzed in detail. We observed the level of intracellular labeled MAP30 using fluorescence microscopy and flow cytometry. And a reporter protein, GAL9, was used to monitor the role of MIC in promoting endosomal escape. We found endosomal escape does not play a role for the enhancer effect of MIC while the effect of MIC on MAP30 is cholesterol dependent and that ganglioside GM1, a lipid raft marker, can competitively inhibit cytotoxicity of MAP30 enhanced by MIC. Finally, we provided some insights into the correlation between the sugar side chain of MIC and its role in enhancing of RIP cytotoxicity and altering of drug cell tropism.

Multicomponent Lipid Nanoparticles for RNA Transfection.

Despite the wide variety of available cationic lipid platforms for the delivery of nucleic acids into cells, the optimization of their composition has not lost its relevance. The purpose of this work was to develop multi-component cationic lipid nanoparticles (LNPs) with or without a hydrophobic core from natural lipids in order to evaluate the efficiency of LNPs with the widely used cationic lipoid DOTAP (1,2-dioleoyloxy-3-[trimethylammonium]-propane) and the previously unstudied oleoylcholine (Ol-Ch), as well as the ability of LNPs containing GM3 gangliosides to transfect cells with mRNA and siRNA. LNPs containing cationic lipids, phospholipids and cholesterol, and surfactants were prepared according to a three-stage procedure. The average size of the resulting LNPs was 176 nm (PDI 0.18). LNPs with DOTAP mesylate were more effective than those with Ol-Ch. Core LNPs demonstrated low transfection activity compared with bilayer LNPs. The type of phospholipid in LNPs was significant for the transfection of MDA-MB-231 and SW 620 cancer cells but not HEK 293T cells. LNPs with GM3 gangliosides were the most efficient for the delivery of mRNA to MDA-MB-231 cells and siRNA to SW620 cells. Thus, we developed a new lipid platform for the efficient delivery of RNA of various sizes to mammalian cells.

High and Persistent Anti-GM1 Antibody Titers Are Associated With Poor Clinical Recovery in Guillain-Barré Syndrome.

Guillain-Barré syndrome (GBS) is an acute immune-mediated polyradiculoneuropathy that may follow a preceding infection inducing a cross-reactive antibody response to glycosphingolipids in peripheral nerves. The immune response in GBS is considered to be short lasting, explaining its monophasic clinical course. However, the disease course varies between patients, and residual deficits frequently occur. The duration of the antibody response has not been defined extensively in GBS, and the persistence of these antibodies may impair clinical recovery. The aim of this study was to determine the titer course of serum antibody titers to the ganglioside GM1 in relation to clinical course and outcome in patients with GBS. Acute-phase sera from patients with GBS included in previous therapeutic trials were screened for anti-GM1 IgG and IgM antibodies in ELISA. Anti-GM1 antibody titers were determined in sera collected at entry and during a 6-month follow-up. Clinical course and outcomes were compared between groups based on the titer course. Anti-GM1 antibodies were detected in 78 (20.7%) of 377 included patients. The anti-GM1 IgG and IgM antibody titer course was highly variable between patients. A subset of anti-GM1-positive patients had persistent anti-GM1 antibodies at 3 months (n = 27/43 [62.8%]) and 6 months (n = 19/41 [46.3%]). Patients with a high anti-GM1 IgG and IgM titer at entry recovered more slowly and less complete than anti-GM1-negative patients (IgG: p = 0.015, IgM: p = 0.03). High vs low IgG titers were independently associated with poor outcome after correcting for known prognostic factors (p = 0.046). Among patients with a high anti-GM1 IgG titer at entry, a slow titer decline was associated with poor outcome at 4 weeks (p = 0.003) and 6 months (p = 0.032). Persistent high IgG titers at 3 and 6 months were associated with poor outcome at 6 months (3 months: p = 0.022, 6 months: p = 0.004). High anti-GM1 IgG and IgM antibody titers at entry and persistent high anti-GM1 IgG antibody titers are associated with poor outcome in patients with GBS. Antibody persistency indicates ongoing antibody production long after the acute disease state in GBS. Further research is required to determine whether antibody persistency interferes with nerve recovery and is a target for treatments.

Exploring Pro-Inflammatory Immunological Mediators: Unraveling the Mechanisms of Neuroinflammation in Lysosomal Storage Diseases.

Lysosomal storage diseases are a group of rare and ultra-rare genetic disorders caused by defects in specific genes that result in the accumulation of toxic substances in the lysosome. This excess accumulation of such cellular materials stimulates the activation of immune and neurological cells, leading to neuroinflammation and neurodegeneration in the central and peripheral nervous systems. Examples of lysosomal storage diseases include Gaucher, Fabry, Tay-Sachs, Sandhoff, and Wolman diseases. These diseases are characterized by the accumulation of various substrates, such as glucosylceramide, globotriaosylceramide, ganglioside GM2, sphingomyelin, ceramide, and triglycerides, in the affected cells. The resulting pro-inflammatory environment leads to the generation of pro-inflammatory cytokines, chemokines, growth factors, and several components of complement cascades, which contribute to the progressive neurodegeneration seen in these diseases. In this study, we provide an overview of the genetic defects associated with lysosomal storage diseases and their impact on the induction of neuro-immune inflammation. By understanding the underlying mechanisms behind these diseases, we aim to provide new insights into potential biomarkers and therapeutic targets for monitoring and managing the severity of these diseases. In conclusion, lysosomal storage diseases present a complex challenge for patients and clinicians, but this study offers a comprehensive overview of the impact of these diseases on the central and peripheral nervous systems and provides a foundation for further research into potential treatments.

MP43-15 MICROSURGICAL VARICOCELE REPAIR IMPROVES SPERM CAPACITATION AND PROBABILITY OF GENERATING A PREGNANCY, AS MEASURED BY PRE- AND POST-OPERATIVE TESTING WITH CAP-SCORE

You have accessJournal of UrologyCME1 Apr 2023MP43-15 MICROSURGICAL VARICOCELE REPAIR IMPROVES SPERM CAPACITATION AND PROBABILITY OF GENERATING A PREGNANCY, AS MEASURED BY PRE- AND POST-OPERATIVE TESTING WITH CAP-SCORE Muhamed Qalawena, Eric Seaman, Jared Johnson, Ahmed El-Sakka, and Joshua Bodie Muhamed QalawenaMuhamed Qalawena More articles by this author , Eric SeamanEric Seaman More articles by this author , Jared JohnsonJared Johnson More articles by this author , Ahmed El-SakkaAhmed El-Sakka More articles by this author , and Joshua BodieJoshua Bodie More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003289.15AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Infertility is a worldwide problem, with up to 40-50% of cases involving male infertility. Varicocele represents the most common correctable cause of male infertility. While semen analysis (SA) remains the primary diagnostic tool of infertility, it does not provide information about sperm function. The Cap-Score is designed to assess sperm capacitation via localization patterns of ganglioside GM-1, which has been shown to be a viable surrogate of capacitation-competent human sperm. The predicted probability of generating a pregnancy (PGP) is a validated metric based on semen volume, concentration, and Cap-Score. PGP is defined as the percent chance of obtaining a pregnancy within three consecutive rounds of intrauterine insemination (IUI). The objective of this study was to determine the effect of microscopic varicocelectomy on sperm capacitation and the probability of generating a pregnancy. METHODS: Data were collected prospectively of 40 consecutive adult men who presented with infertility confirmed by SA and found to have a varicocele on exam or ultrasound who underwent unilateral or bilateral subinguinal microscopic varicocelectomy. We recorded pre and post-operative SA, Cap-Score, and PGP with a 3-month follow up. Values were compared using paired t-test and Wilcox rank-sum test. RESULTS: Of the 40 men enrolled, 29 (72.5%) demonstrated improved Cap-Score with an average increase of 4% (p=0.001). The absolute change in probability of generating a pregnancy was 6% higher (p=0.001) after varicocelectomy, which represents a 25% relative increase in PGP. The change in Cap-Score was not associated with the grade of varicocele (p=0.0703) or whether the patient had a unilateral or bilateral repair (p=0.9682). There were no differences in semen volume (p=0.061) or morphology (p=0.091), however, there was improvement in sperm motility (p=0.021), total sperm count (p=0.030) and concentration (p=0.004). CONCLUSIONS: It is known that varicocelectomy improves semen parameters and chances of conception in the majority of cases, including pregnancies via intercourse or via assisted reproduction. This study confirms that varicocelectomy augments male fertility by improving sperm capacitation, and that varicocele repair improves the probability of generating an IUI pregnancy to a statistically-significant degree. The improvement in sperm capacitation ability may explain how varicocele repair may improve the chance of pregnancy, regardless of standard semen parameter improvements. Source of Funding: This study did not receive industry support. The only external funding for the study came from doctor M. Qalawena, a scholar visiting the University of Minnesota from the faculty of Medicine Suez Canal University, Egypt, whose personal educational grant by the Egyptian ministry of higher education funded the sixteen tests for the eight patients contributed from the University of Minnesota. Patients from the New Jersey site had received Cap-Score testing by Androvia LifeSciences Lab at patient expense. Physicians received no funding from Androvia for running the study, and the Androvia Labs did not have editorial control of the study results © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e607 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Muhamed Qalawena More articles by this author Eric Seaman More articles by this author Jared Johnson More articles by this author Ahmed El-Sakka More articles by this author Joshua Bodie More articles by this author Expand All Advertisement PDF downloadLoading ...

Antiviral activity of glucosylceramide synthase inhibitors in alphavirus infection of the central nervous system.

Virus-induced CNS diseases impose a considerable human health burden worldwide. For many viral CNS infections, neither antiviral drugs nor vaccines are available. In this study, we examined whether the synthesis of glycosphingolipids, major membrane lipid constituents, could be used to establish an antiviral therapeutic target. We found that neuroinvasive Sindbis virus altered the sphingolipid levels early after infection in vitro and increased the levels of gangliosides GA1 and GM1 in the sera of infected mice. The alteration in the sphingolipid levels appears to play a role in neuroinvasive Sindbis virus replication, as treating infected cells with UDP-glucose ceramide glucosyltransferase (UGCG) inhibitors reduced the replication rate. Moreover, the UGCG inhibitor GZ-161 increased the survival rates of Sindbis-infected mice, most likely by reducing the detrimental immune response activated by sphingolipids in the brains of Sindbis virus-infected mice. These findings suggest a role for glycosphingolipids in the host immune response against neuroinvasive Sindbis virus and suggest that UGCG inhibitors should be further examined as antiviral therapeutics for viral infections of the CNS.

Design, preparation and characterization of octopus-like self-releasing intracellular protein transporter LEB5 based on Escherichia coli heat-labile enterotoxin

Despite the great potential of protein drugs as intracellular therapeutic agents, the unmet challenge in breaking through the cell membrane barrier and delivering them to intracellular targets remains. Therefore, developing safe and effective delivery vehicles is critical for fundamental biomedical research and clinical applications. In this study, we designed an octopus-like self-releasing intracellular protein transporter, the LEB5, based on the heat-labile enterotoxin. This carrier comprises five identical units, each of which has three main components: a linker, a self-releasing enzyme sensitivity loop, and the LTB transport domain. The LEB5 comprises five purified monomers that self-assemble to create a pentamer with ganglioside GM1 binding capacity. The fluorescent protein EGFP was used as a reporter system to identify the LEB5 features. The high-purity fusion protein ELEB monomer was produced from modified bacteria carrying pET24a(+)-eleb recombinant plasmids. EGFP protein could effectively detach from LEB5 by low dosage trypsin, according to electrophoresis analysis. The transmission electron microscopy results indicate that both LEB5 and ELEB5 pentamers exhibit a relatively regularly spherical shape, and the differential scanning calorimetry measurements further suggest that these proteins possess excellent thermal stability. Fluorescence microscopy revealed that LEB5 translocated EGFP into different cell types. Flow cytometry showed cellular differences in the transport capacity of LEB5. According to the confocal microscopy, fluorescence analysis and western blotting data, EGFP was transferred to the endoplasmic reticulum by the LEB5 carrier, detached from LEB5 by cleavage of the enzyme-sensitive loop, and released into the cytoplasm. Within the dosage range of LEB5 10–80 μg/mL, cell counting kit-8 assay revealed no significant changes in cell viability. These results demonstrated that LEB5 is a safe and effective intracellular self-releasing delivery vehicle capable of transporting and releasing protein medicines into cells.

Synthesis and biological activity of ganglioside GM3 analogues with a (S)-CHF-Sialoside linkage and an alkyne tag.

The alkyne tag, consisting of only two carbons, is widely used as a bioorthogonal functional group due to its compactness and nonpolar structure, and various probes consisting of lipids bearing an alkyne tag have been developed. Here, we designed and synthesized analogues of ganglioside GM3 bearing an alkyne tag in the fatty acid moiety and evaluated the effect of the alkyne tag on the biological activity. To eliminate the influence of other factors such as degradation of the glycan chain when evaluating biological activity in a cellular environment, we introduced the tag into sialidase-resistant (S)-CHF-linked GM3 analogues developed by our group. The designed analogues were efficiently synthesized by tuning the protecting group of the glucosylsphingosine acceptor. The growth-promoting effect of these analogues on Had-1 cells was dramatically altered depending upon the position of the alkyne tag.

Identification of Myelin Basic Protein Proximity Interactome Using TurboID Labeling Proteomics.

Myelin basic protein (MBP) is one of the key structural elements of the myelin sheath and has autoantigenic properties in multiple sclerosis (MS). Its intracellular interaction network is still partially deconvoluted due to the unfolded structure, abnormally basic charge, and specific cellular localization. Here we used the fusion protein of MBP with TurboID, an engineered biotin ligase that uses ATP to convert biotin to reactive biotin-AMP that covalently attaches to nearby proteins, to determine MBP interactome. Despite evident benefits, the proximity labeling proteomics technique generates high background noise, especially in the case of proteins tending to semi-specific interactions. In order to recognize unique MBP partners, we additionally mapped protein interaction networks for deaminated MBP variant and cyclin-dependent kinase inhibitor 1 (p21), mimicking MBP in terms of natively unfolded state, size and basic amino acid clusters. We found that in the plasma membrane region, MBP is colocalized with adhesion proteins occludin and myelin protein zero-like protein 1, solute carrier family transporters ZIP6 and SNAT1, Eph receptors ligand Ephrin-B1, and structural components of the vesicle transport machinery-synaptosomal-associated protein 23 (SNAP23), vesicle-associated membrane protein 3 (VAMP3), protein transport protein hSec23B and cytoplasmic dynein 1 heavy chain 1. We also detected that MBP potentially interacts with proteins involved in Fe2+ and lipid metabolism, namely, ganglioside GM2 activator protein, long-chain-fatty-acid-CoA ligase 4 (ACSL4), NADH-cytochrome b5 reductase 1 (CYB5R1) and metalloreductase STEAP3. Assuming the emerging role of ferroptosis and vesicle cargo docking in the development of autoimmune neurodegeneration, MBP may recruit and regulate the activity of these processes, thus, having a more inclusive role in the integrity of the myelin sheath.

Process Engineering and Glycosyltransferase Improvement for Short Route Chemoenzymatic Total Synthesis of GM1 Gangliosides.

Large-scale synthesis of GM1, an important ganglioside in mammalian cells especially those in the nervous system, is needed to explore its therapeutic potential. Biocatalytic production is a promising platform for such a purpose. We report herein the development of process engineering and glycosyltransferase improvement strategies to advance chemoenzymatic total synthesis of GM1. Firstly, a new short route was developed for chemical synthesis of lactosylsphingosine from the commercially available Garner's aldehyde. Secondly, two glycosyltransferases including Campylobacter jejuni β1-4GalNAcT (CjCgtA) and β1-3-galactosyltransferase (CjCgtB) were improved on their soluble expression in E. coli and enzyme stability by fusing with an N-terminal maltose binding protein (MBP). Thirdly, the process for enzymatic synthesis of GM1 sphingosines from lactosylsphingosine was engineered by developing a multistep one-pot multienzyme (MSOPME) strategy without isolating intermediate glycosphingosines and by adding a detergent, sodium cholate, to the later enzymatic glycosylation steps. Installation of a desired fatty acyl chain to GM1 glycosphingosines led to the formation of target GM1 gangliosides. The combination of glycosyltransferase improvement with chemical and enzymatic process engineering represents a significant advance in obtaining GM1 gangliosides containing different sialic acid forms by total chemoenzymatic synthesis in a short route and with high efficiency.

Autophagic flux is impaired in the brain tissue of Tay-Sachs disease mouse model.

Tay-Sachs disease is a lethal lysosomal storage disorder caused by mutations in the HexA gene encoding the α subunit of the lysosomal β-hexosaminidase enzyme (HEXA). Abnormal GM2 ganglioside accumulation causes progressive deterioration in the central nervous system in Tay-Sachs patients. Hexa-/- mouse model failed to display abnormal phenotype. Recently, our group generated Hexa-/-Neu3-/- mouse showed severe neuropathological indications similar to Tay-Sachs patients. Despite excessive GM2 ganglioside accumulation in the brain and visceral organs, the regulation of autophagy has not been clarified yet in the Tay-Sachs disease mouse model. Therefore, we investigated distinct steps of autophagic flux using markers including LC3 and p62 in four different brain regions from the Hexa-/-Neu3-/- mice model of Tay-Sachs disease. Our data revealed accumulated autophagosomes and autophagolysosomes indicating impairment in autophagic flux in the brain. We suggest that autophagy might be a new therapeutic target for the treatment of devastating Tay-Sachs disease.

TAY-SACHS DISEASE IN A CHILD: A RARE CASE REPORT ,GGH KURNOOL

The neurodegenerative condition known as Tay-Sachs disease is inherited in an autosomal recessive pattern and is caused by an abnormal accumulation of the cell membrane glycolipid and GM2 ganglioside within the lysosomes of affected cells. A lack of the isoenzyme -hexosaminidase A, which is synthesised in the endoplasmic reticulum, is the root cause of this condition. In patients who have Tay-Sachs disease, the first few months of life are characterised by normal motor development, followed by gradual weakening and loss of motor abilities beginning around 2 to 6 months of life. Due to the irreversible nature of neurodegeneration, death typically occurs between the ages of 4 and 5 years. The hexosaminidase enzyme assay and DNA analysis of the HEXA gene are two methods that can be used to diagnose TaySachs disease. On the other hand, there is no specific treatment that has been established. We discuss here a case of TaySachs disease found in an 9-month-old male child who presented with loss of milestones and seizure symptoms. Upon examination of the fundus, it was found that this patient had cherry red spot in the macula. In the enzymatic assay, the hexosaminidase A activity was zero percent, and DNA analysis revealed a mutation in which glutamine was replaced by a stop codon at position 390

Restoration of Adult Neurogenesis by Intranasal Administration of Gangliosides GD3 and GM1 in The Olfactory Bulb of A53T Alpha-Synuclein-Expressing Parkinson's-Disease Model Mice.

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting the body and mind of millions of people in the world. As PD progresses, bradykinesia, rigidity, and tremor worsen. These motor symptoms are associated with the neurodegeneration of dopaminergic neurons in the substantia nigra. PD is also associated with non-motor symptoms, including loss of smell (hyposmia), sleep disturbances, depression, anxiety, and cognitive impairment. This broad spectrum of non-motor symptoms is in part due to olfactory and hippocampal dysfunctions. These non-motor functions are suggested to be linked with adult neurogenesis. We have reported that ganglioside GD3 is required to maintain the neural stem cell (NSC) pool in the subventricular zone (SVZ) of the lateral ventricles and the subgranular layer of the dentate gyrus (DG) in the hippocampus. In this study, we used nasal infusion of GD3 to restore impaired neurogenesis in A53T alpha-synuclein-expressing mice (A53T mice). Intriguingly, intranasal GD3 administration rescued the number of bromodeoxyuridine + (BrdU +)/Sox2 + NSCs in the SVZ. Furthermore, the administration of gangliosides GD3 and GM1 increases doublecortin (DCX)-expressing immature neurons in the olfactory bulb, and nasal ganglioside administration recovered the neuronal populations in the periglomerular layer of A53T mice. Given the relevance of decreased ganglioside on olfactory impairment, we discovered that GD3 has an essential role in olfactory functions. Our results demonstrated that intranasal GD3 infusion restored the self-renewal ability of the NSCs, and intranasal GM1 infusion promoted neurogenesis in the adult brain. Using a combination of GD3 and GM1 has the potential to slow down disease progression and rescue dysfunctional neurons in neurodegenerative brains.

Ganglioside GM3 prevents high fat diet-induced hepatosteatosis via attenuated insulin signaling pathway.

Gangliosides, sialic acid-containing glycosphingolipids, are widely involved in regulations of signal transductions to control cellular functions. It has been suggested that GM3, the simplest structure among gangliosides, is involved in insulin resistance, whereas it remains unclear whether insulin signaling diminished by GM3 actually aggravates the pathological conditions in metabolic disorders. Moreover, the functional roles of gangliosides in the regulation of insulin signaling have not yet been fully elucidated in liver or hepatocytes despite that it is one of the major insulin-sensitive organs. To understand physiological roles of GM3 in metabolic homeostasis in liver, we conducted a high fat diet (HFD) loading experiment using double knockout (DKO) mice of GM2/GD2 synthase and GD3 synthase, which lack all gangliosides except GM3, as well as wild-type (WT) mice. DKO mice were strikingly resistant to HFD-induced hepatosteatosis, and hepatic lipogenesis-related molecules including insulin signaling components were down-regulated in HFD-fed DKO. Furthermore, we established primary hepatocyte cultures from DKO and WT mice, and examined their responses to insulin in vitro. Following insulin stimulation, DKO hepatocytes expressing GM3 showed attenuated expression and/or activations in the downstream components compared with WT hepatocytes expressing GM2. While insulin stimulation induced lipogenic proteins in hepatocytes from both genotypes, their expression levels were lower in DKO than in WT hepatocytes after insulin treatment. All our findings suggest that the modified gangliosides, i.e., a shift to GM3 from GM2, might exert a suppressive effect on lipogenesis by attenuating insulin signaling at least in mouse hepatocytes, which might result in protection of HFD-induced hepatosteatosis.