Expression Of GM1 Research Articles

Increased Expression of Simple Ganglioside Species GM2 and GM3 Detected by MALDI Imaging Mass Spectrometry in a Combined Rat Model of Aβ Toxicity and Stroke.

The aging brain is often characterized by the presence of multiple comorbidities resulting in synergistic damaging effects in the brain as demonstrated through the interaction of Alzheimer’s disease (AD) and stroke. Gangliosides, a family of membrane lipids enriched in the central nervous system, may have a mechanistic role in mediating the brain’s response to injury as their expression is altered in a number of disease and injury states. Matrix-Assisted Laser Desorption Ionization (MALDI) Imaging Mass Spectrometry (IMS) was used to study the expression of A-series ganglioside species GD1a, GM1, GM2, and GM3 to determine alteration of their expression profiles in the presence of beta-amyloid (Aβ) toxicity in addition to ischemic injury. To model a stroke, rats received a unilateral striatal injection of endothelin-1 (ET-1) (stroke alone group). To model Aβ toxicity, rats received intracerebralventricular (icv) injections of the toxic 25-35 fragment of the Aβ peptide (Aβ alone group). To model the combination of Aβ toxicity with stroke, rats received both the unilateral ET-1 injection and the bilateral icv injections of Aβ₂₅₋₃₅ (combined Aβ/ET-1 group). By 3 d, a significant increase in the simple ganglioside species GM2 was observed in the ischemic brain region of rats who received a stroke (ET-1), with or without Aβ. By 21 d, GM2 levels only remained elevated in the combined Aβ/ET-1 group. GM3 levels however demonstrated a different pattern of expression. By 3 d GM3 was elevated in the ischemic brain region only in the combined Aβ/ET-1 group. By 21 d, GM3 was elevated in the ischemic brain region in both stroke alone and Aβ/ET-1 groups. Overall, results indicate that the accumulation of simple ganglioside species GM2 and GM3 may be indicative of a mechanism of interaction between AD and stroke.

Identification and functional characterization of intracellular sialidase NeuA3 from Streptomyces avermitilis

Sialidases (EC 3.2.1.18), glycosidases that cleave the linkages whereby sialic acids are attached to glycoconjugates, are found in most bacterial species. Because sialidases can convert polysialogangliosides to monosialoganglioside GM1, they have potential clinical application for treatment of human neurological and other disorders including Alzheimer's disease, Parkinson's disease, and spinal cord injury. Sialidases with high substrate specificity are desirable for more efficient GM1 production. In this study, the sialidase neuA3 gene from the non-pathogenic bacterium Streptomyces avermitilis, which is commonly used for industrial applications, was analyzed, cloned, and expressed in E. coli BL21 (DE3). Purified NeuA3 enzyme was characterized using 2′-(4-methylumbelliferyl)-α-d-N-acetylneuraminic acid (4-MUN) as a synthetic substrate. NeuA3 has a low molecular weight (∼38kDa), showed strong stability in the presence of various divalent metal ions and temperature and pH values, preferentially cleaved α2,3- and α2,6-linked sialic acids from gangliosides, and efficiently converted crude porcine brain gangliosides to GM1. NeuA3 treatment of malignant human bladder cancer cells YTS-1 presented enhanced cell surface expression of GM1. The novel sialidase NeuA3 will be useful for functional studies of sialylated oligosaccharides and other sialoglycoconjugates, especially for studying the functions of GM1 in cancer research.

GM3 and cancer.

Our studies during the early 1970s showed that expression of GM3, the simplest ganglioside and an abundant animal cell membrane component, is reduced during malignant transformation of cells by oncogenic viruses. Levels of mRNA for GM3 synthase were reduced in avian and mammalian cells transformed by oncoprotein "v-Jun", and overexpression of GM3 synthase in the transformed cells caused reversion from transformed to normal cell-like phenotype. GM3 has a well-documented inhibitory effect on activation of growth factor receptors (GFRs), particularly epidermal GFR (EGFR). De-N-acetyl GM3, which is expressed in some invasive human cancer cells, has an enhancing effect on EGFR activation. The important role of the sialosyl group of GM3 was demonstrated using NEU3, a plasma membrane-associated sialidase that selectively remove sialic acids from gangliosides GM3 and GD1a and is up-regulated in many human cancer cells. GM3 is highly enriched in a type of membrane microdomain termed "glycosynapse", and forms complexes with co-localized cell signaling molecules, including Src family kinases, certain tetraspanins (e.g., CD9, CD81, CD82), integrins, and GFRs (e.g., fibroblast growth factor receptor and hepatocyte growth factor receptor c-Met). Studies by our group and others indicate that GM3 modulates cell adhesion, growth, and motility by altering molecular organization in glycosynaptic microdomains and the activation levels of co-localized signaling molecules that are involved in cancer pathogenesis.

Midazolam inhibits the formation of amyloid fibrils and GM1 ganglioside-rich microdomains in presynaptic membranes through the gamma-aminobutyric acid A receptor

Recent studies have suggested that a positive correlation exists between surgical interventions performed under general anesthesia and the risk of developing Alzheimer's disease (AD) in the late postoperative period. It has been reported that amyloid β-protein (Αβ) fibrillogenesis, which is closely related to AD, is accelerated by exposure to anesthetics. However, the mechanisms underlying these effects remain uncertain. This study was designed to investigate whether the anesthetic midazolam affects Αβ fibrillogenesis, and if so, whether it acts through GM1 ganglioside (GM1) on the neuronal surface. Midazolam treatment decreased GM1 expression in the detergent-resistant membrane microdomains of neurons, and these effects were regulated by the gamma-aminobutyric acid-A receptor. Midazolam inhibited Αβ fibril formation from soluble Αβ on the neuronal surface. In addition, midazolam suppressed GM1-induced fibril formation in a cell-free system. Moreover, midazolam inhibited the formation of Αβ assemblies in synaptosomes isolated from aged mouse brains. These finding suggested that midazolam has direct and indirect inhibitory effects on Αβ fibrillogenesis.

Therapeutic activity of glycoengineered anti-GM2 antibodies to malignant mesothelioma. GM2 expression in a clinical malignant pleural mesothelioma specimen determined by anti-GM2 antibody BIW-8962

Cancer ScienceVolume 106, Issue 1 p. January cover-January cover Cover ImageOpen Access Therapeutic activity of glycoengineered anti-GM2 antibodies to malignant mesothelioma. GM2 expression in a clinical malignant pleural mesothelioma specimen determined by anti-GM2 antibody BIW-8962 Qi Li, Qi LiSearch for more papers by this authorWei Wang, Wei WangSearch for more papers by this authorYusuke Machino, Yusuke MachinoSearch for more papers by this authorTadaaki Yamada, Tadaaki YamadaSearch for more papers by this authorKenji Kita, Kenji KitaSearch for more papers by this authorMasanobu Oshima, Masanobu OshimaSearch for more papers by this authorYoshitaka Sekido, Yoshitaka SekidoSearch for more papers by this authorMami Tsuchiya, Mami TsuchiyaSearch for more papers by this authorYui Suzuki, Yui SuzukiSearch for more papers by this authorKen-ichiro Nan-ya, Ken-ichiro Nan-yaSearch for more papers by this authorShigeru Iida, Shigeru IidaSearch for more papers by this authorKazuyasu Nakamura, Kazuyasu NakamuraSearch for more papers by this authorShotaro Iwakiri, Shotaro IwakiriSearch for more papers by this authorKazumi Itoi, Kazumi ItoiSearch for more papers by this authorSeiji Yano, Seiji YanoSearch for more papers by this author Qi Li, Qi LiSearch for more papers by this authorWei Wang, Wei WangSearch for more papers by this authorYusuke Machino, Yusuke MachinoSearch for more papers by this authorTadaaki Yamada, Tadaaki YamadaSearch for more papers by this authorKenji Kita, Kenji KitaSearch for more papers by this authorMasanobu Oshima, Masanobu OshimaSearch for more papers by this authorYoshitaka Sekido, Yoshitaka SekidoSearch for more papers by this authorMami Tsuchiya, Mami TsuchiyaSearch for more papers by this authorYui Suzuki, Yui SuzukiSearch for more papers by this authorKen-ichiro Nan-ya, Ken-ichiro Nan-yaSearch for more papers by this authorShigeru Iida, Shigeru IidaSearch for more papers by this authorKazuyasu Nakamura, Kazuyasu NakamuraSearch for more papers by this authorShotaro Iwakiri, Shotaro IwakiriSearch for more papers by this authorKazumi Itoi, Kazumi ItoiSearch for more papers by this authorSeiji Yano, Seiji YanoSearch for more papers by this author First published: 23 January 2015 https://doi.org/10.1111/cas.12590AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume106, Issue1January 2015Pages January cover-January cover RelatedInformation

Therapeutic activity of glycoengineered anti-GM2 antibodies against malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive neoplasm that arises from the pleural, pericardial, or peritoneal lining. Although surgery, chemotherapy, radiotherapy, and combinations of these therapies are used to treat MPM, the median survival of such patients is dismal. Therefore, there is a compelling need to develop novel therapeutics with different modes of action. Ganglioside GM2 is a glycolipid that has been shown to be overexpressed in various types of cancer. However, there are no published reports regarding the use of GM2 as a potential therapeutic target in cases of MPM. In this study, we evaluated the efficacy of the anti-GM2 antibody BIW-8962 as an anti-MPM therapeutic using in vitro and in vivo assays. Consequently, the GM2 expression in the MPM cell lines was confirmed using flow cytometry. In addition, eight of 11 cell lines were GM2-positive (73%), although the GM2 expression was variable. BIW-8962 showed a significant antibody-dependent cellular cytotoxicity activity against the GM2-expressing MPM cell line MSTO-211H, the effect of which depended on the antibody concentration and effector/target ratio. In an in vivo orthotropic mouse model using MSTO-211H cells, BIW-8962 significantly decreased the incidence and size of tumors. Additionally, the GM2 expression was confirmed in the MPM clinical specimens. Fifty-eight percent of the MPM tumors were positive for GM2, with individual variation in the intensity and frequency of staining. These data suggest that anti-GM2 antibodies may become a therapeutic option for MPM patients.

Relationship between ganglioside GD1a and inflammatory response in the coculture of human endothelial cells with porcine endothelial cells

Gangliosides are ubiquitous components of cell membranes that can act as mediators of cell adhesion and signal transduction. However, their interaction with adhesion molecules in vascular grafts following xenotransplantation is not yet clearly understood. In this study, human umbilical vein endothelial cells (HUVECs) were cocultured with porcine aortic endothelial cells (PAECs) in order to investigate the expression patterns of gangliosides, inflammation factors, and the mRNA levels of adhesion molecules by PCR and western blot. The expression of gangliosides GM3 and GM1 was detected in both HUVECs and PAECs, while GD3 was expressed only in PAECs. However, when HUVECs were cocultured with PAECs, GD1a expression was newly detected. In addition, we observed the mRNA expression levels of adhesion molecules including such as E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and platelet endothelial cell adhesion molecule-1 were higher in cocultured HUVECs with PAECs than in either HUVECs or PAECs cultured alone. Furthermore, when HUVECs were cocultured with PAECs, cell growth was significantly inhibited compared with either HUVECs or PAECs. The growth inhibition of both cocultured cells and HUVECs by lipopolysaccharide was significantly increased by GD1a treatment. When HUVECs with PAECs were cocultured, expression of GD1a and inflammatory factors including tumor necrosis factor-α (TNF-α), p65, and p50 significantly increased. These results suggest that GD1a interact with components of the proinflammatory response pathway in xenotransplantation. Therefore, may be relevant for designing future therapeutic strategies intended to prolong xenograft survival.

Control of homeostatic and pathogenic balance in adipose tissue by ganglioside GM3.

Ganglioside GM3 (Siaα2-3Galβ1-4Glcβ1-1Cer) has been known to participate in insulin signaling by regulating the association of the insulin receptor in caveolae microdomains (lipid rafts), which is essential for the execution of the complete insulin metabolic signaling in adipocytes. Macrophage-secreted factors including proinflammatory cytokines, tumor necrosis factor-α and interleukin-1β, in adipose tissues have been known to limit the local adipogenesis and induce insulin resistance; however, the interplay between adipocytes and macrophages upon regulation of GM3 expression is not clear. GM3 was virtually absent in primary adipocytes differentiated from macrophage-depleted mesenteric stromal vesicular cells, which accompanies enhancement of insulin signaling and adipogenesis. We found that the expression of GM3 is governed by soluble factors including steady-state levels of proinflammatory cytokines secreted from resident macrophages. The direct involvement of GM3 in insulin signaling is demonstrated by the fact that embryonic fibroblasts obtained from GM3 synthase (GM3S)-deficient mice have increased insulin signaling, when compared with wild-type embryonic fibroblasts, which in turn leads to enhanced adipogeneis. In addition, GM3 expression in primary adipocytes is increased under proinflammatory conditions as well as in adipose tissue of diet-induced obese mice. Moreover, GM3S-deficient mice fed high-fat diets become obese but are resistant to the development of insulin resistance and chronic low-grade inflammatory states. Thus, GM3 functions as a physiological regulatory factor of the balance between homeostatic and pathological states in adipocytes by modulating insulin signaling in lipid rafts.

Possible paraneoplastic etiology in a case of Guillain-Barré syndrome with tumoral expression of ganglioside GM3

Paraneoplastic neurological syndromes occur most frequently with small cell lung cancer. We report a 73-year-old man who had suffered from small cell lung cancer, with a fraction of the patient's malignant cells expressing membrane ganglioside GM3, and had developed Guillain–Barre syndrome with serum positivity for anti-GM3 immunoglobulin G antibody when assayed with phosphatidic acid. The distribution of GM3 in myelin labeled with anti-human GM3 antibodies corresponded well to that labeled with the patient's serum, but not with control sera. Intravenous immunoglobulins and chemotherapy for cancer resolved the symptoms of Guillain–Barre syndrome. These observations suggest that autoantibodies against conformational epitopes formed by GM3 and phosphatidic acid in cancers cross-react with neural tissue, probably as a result of molecular mimicry, and might thus underlie paraneoplastic Guillain–Barre syndrome.

Leptin inhibits amyloid β-protein fibrillogenesis by decreasing GM1 gangliosides on the neuronal cell surface through PI3K/Akt/mTOR pathway.

Leptin is a centrally acting hormone that controls metabolic pathways. Recent epidemiological studies suggest that plasma leptin is protective against Alzheimer's disease. However, the mechanism that underlies this effect remains uncertain. To investigate whether leptin inhibits the assembly of amyloid β-protein (Aβ) on the cell surface of neurons, we treated primary neurons with leptin. Leptin treatment decreased the GM1 ganglioside (GM1) levels in the detergent-resistant membrane microdomains (DRMs) of neurons. The increase in GM1 expression induced by leptin was inhibited after pre-treatment with inhibitors of phosphatidylinositol 3-kinase (LY294002), Akt (triciribine) and the mammalian target of rapamycin (i.e. rapamycin), but not by an inhibitor of extracellular signal-regulated kinase (PD98059). In addition, pre-treatment with these reagents blocked the induction of GM1 in DRMs by leptin. Furthermore, Aβ assembly on the cell surface of neurons was inhibited greatly after treatment with leptin. This reduction was markedly inhibited after pre-treatment with LY294002, triciribine, and rapamycin. These results suggest that leptin significantly inhibits Aβ assembly by decreasing GM1 expression in DRMs of the neuronal surface through the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway. These findings highlight the importance of understanding the function of leptin in AD brains. In this study, our aim was to determine whether leptin regulates the expression and localization of GM1 on the neuronal membrane and if it induces the formation of Aβ assembly on the cell surface of neurons. Our results suggest that leptin regulates the expression of GM1 in DRMs of the neuronal membranes. Moreover, leptin does not seem to facilitate fibrillogenesis of exogenously added soluble Aβ from the cell surface of neurons.

Corrigendum: involvement of a non-human sialic Acid in human cancer.

Antibodies 14F7 and the corresponding anti-idiotype 1E10 (racotumomab, misspelled as racotumumab) were mistakenly conflated in this review. 14F7 reacts with (Neu5Gc)GM3, was recently humanized (1), but has not yet been tested in clinical trials. Racotumomab induced a human anti-(Neu5Gc)GM3 immune response, which correlated with longer median survival in non-small cell lung cancer (2). The first clinical trial result using racotumomab was actually published in 2002 (3). A phase III trial testing racotumomab in advanced non-small cell lung cancer began in 2011, and is currently recruiting (NCT01460472). These studies do not consider dietary Neu5Gc intake and incorporation as a variable that could affect (Neu5Gc)GM3 expression by human cancers.

GM1 controlled lateral segregation of tyrosine kinase Lck predispose T-cells to cell-derived galectin-1-induced apoptosis

One prominent immunoregulatory function of galectin-1 (Gal-1), a β-galactoside binding mammalian lectin, is induction of apoptosis in activated T-cells by a process depending on the activity of Src family tyrosine kinase, Lck. Although the requirement for Lck in Gal-1 induced T-cell death and the ability of Gal-1 to affect the membrane localization of extracellular Gal-1-binding proteins have been well documented, the consequence of the complex and related reorganization of extra- and intracellular signaling components upon Gal-1 treatment of T-cells has not yet been revealed. Therefore, we have analyzed the plasma membrane movement of Lck upon Gal-1 triggered signaling, and the significance of this event in Gal-1 induced T-cell death. Non-receptor tyrosine kinase, Lck primarily localized in the synapse of tumor cell-T-cell during 15min of the established direct cell contact. Later, after 30min, a lateral segregation of Lck from the cell synapse was observed. The migration of Lck to the opposite of the cell contact apparently depended on the expression and cell surface presentation of Gal-1 on the effector (tumor) cells and was accompanied by phosphorylation on the negative regulatory tyrosine residue, Tyr505. Receptor tyrosine phosphatase, CD45 played crucial role in this event since CD45 deficiency or inhibition of its phosphatase activity resulted in the failure of Lck membrane movement. Level of the Gal-1-binding glycolipid GM1 ganglioside also essentially regulated Lck localization. Segregation of Lck and Gal-1 induced apoptosis was diminished in T-cells with low GM1 expression compared to T-cells with high GM1. Our results show that spatial regulation of Lck by CD45 and GM1 ganglioside determines the outcome of apoptotic response to Gal-1 and this local regulation may occur only upon intimate effector (Gal-1 expressing) cell-T-cell attachment.

Effect of gangliosides on LPS stimulation and nitric oxide release in porcine kidney cell line PK15

Gangliosides, which are glycosphingolipids containing sialic acid, play important regulatory roles in cell proliferation and adhesion, survival and immunosuppressive activity. In this study, we investigated whether gangliosides can affect cell viability in the porcine kidney (PK) cell line, PK15, when stimulated with lipopolysaccharide (LPS). As the amount of LPS that PK15 cells were treated with was increased, the cell proliferation decreased, whereas nitric oxide (NO) production increased. High-performance thin-layer chromatography (HPTLC) and immunofluorescence analyses showed that GM3 and GM2 ganglioside expression significantly decreased in LPS-stimulated PK15 compared to unstimulated PK15. UDP-glucose ceramide glucosyltransferase (Ugcg), which catalyzes the initial step in the glycosphingolipid biosynthesis pathway, was knocked-down in PK15 by using short hairpin RNA (shRNA). Western blot and HPTLC analyses showed that the Ugcg protein expression decreased and the ganglioside expression decreased in the Ugcg-knockdown (UKD) PK15. There was a greater decrease in cell proliferation in LPS-stimulated UKD PK15 cells than in LPS-stimulated PK15 cells without the UKD. However, the increase in NO release was greater in LPS-stimulated UKD PK15 cells than in LPS-stimulated PK15 cells without the UKD. These findings suggest that gangliosides may interact with components of the inflammatory response pathway and, thus, are relevant for the design of future therapeutic strategies intended to prolong xenotransplantation.

Trimeric Tn Antigen on Syndecan 1 Produced by ppGalNAc-T13 Enhances Cancer Metastasis via a Complex Formation with Integrin α5β1 and Matrix Metalloproteinase 9

We demonstrated previously that ppGalNAc-T13 (T13), identified as an up-regulated gene with increased metastasis in a DNA microarray, generated trimeric Tn (tTn) antigen (GalNAcα1-Ser/Thr)3 on Syndecan 1 in highly metastatic sublines of Lewis lung cancer. However, it is not known how tTn antigen regulates cancer metastasis. Here, we analyzed the roles of tTn antigen in cancer properties. tTn antigen on Syndecan 1 increased cell adhesion to fibronectin in an integrin-dependent manner. Furthermore, cell adhesion to fibronectin induced phosphorylation of focal adhesion kinase and paxillin in T13-transfectant cells. In the search of Syndecan 1-interacting molecules, it was demonstrated that tTn antigen-carrying Syndecan 1 interacted with integrin α5β1 and matrix metalloproteinase 9 and that these molecules shifted to a glycolipid-enriched microdomain/rafts along with increased metastatic potential in T13-transfectant cells. We also identified a tTn substitution site on Syndecan 1, demonstrating that tTn on Syndecan 1 is essential for the interaction with integrin α5β1 as well as for the reaction with mAb MLS128. These data suggest that high expression of the ppGalNAc-T13 gene generates tTn antigen on Syndecan 1 under reduced expression of GM1, leading to enhanced invasion and metastasis via the formation of a molecular complex consisting of integrin α5β1, Syndecan 1, and MMP-9 in the glycolipid-enriched microdomain/rafts.

Ganglioside GM3 promotes HGF-stimulated motility of murine hepatoma cell through enhanced phosphorylation of cMet at specific tyrosine sites and PI3K/Akt-mediated migration signaling

Ganglioside GM3 plays a well-documented and important role in the regulation of tumor cell proliferation, invasion, and metastasis by modulating tyrosine kinase growth factor receptors. However, the effect of GM3 on the hepatocyte growth factor receptor (HGFR, cMet) has not been fully delineated. In the current study, we investigated how GM3 affects cMet signaling and HGF-stimulated cell motility and migration using three hepatic cancer cell lines of mouse (Hca/A2, Hca/16A3, and Hepa1-6). Decreasing GM3 expression with the use of P4, a specific inhibitor for ganglioside synthesis inhibited the HGF-stimulated phosphorylation of cMet and activity of PI3K/Akt signaling pathway. In contrast, the increased expression of GM3 as a result of adding exogenous GM3 enhanced the HGF-stimulated phosphorylation of cMet and activity of PI3K/Akt signaling pathway. Furthermore, HGF-stimulated cell motility and migration in vitro were inhibited by reduced expression of GM3 and enhanced by increased expression of GM3. All the observations indicate that ganglioside GM3 promotes HGF-stimulated motility of murine hepatoma cell through enhanced phosphorylation of cMet at specific tyrosine sites and PI3K/Akt-mediated migration signaling.

Propofol and Thiopental Suppress Amyloid Fibril Formation and GM1 Ganglioside Expression through the γ-Aminobutyric Acid A Receptor

The incidence of Alzheimer disease may increase after surgical interventions. Amyloid β-protein (Aβ) fibrillogenesis, which is closely related to Alzheimer disease, is reportedly accelerated by exposure to anesthetics. However, the effects of GM1 ganglioside (GM1) on Αβ fibrillogenesis have not yet been reported. The current study was designed to examine whether the anesthetics propofol and thiopental are associated with Αβ assembly and GM1 expression on the neuronal cell surface. PC12N cells and cultured neuronal cells were treated with propofol or thiopental, and GM1 expression in treated and untreated cells was determined by the specific binding of horseradish peroxidase-conjugated cholera toxin subunit B (n = 5). The effects of an inhibitor of the γ-aminobutyric acid A receptor was also examined (n= 5). In addition, the effects of the anesthetics on GM1 liposome-induced Αβ assembly were investigated (n = 5). Finally, the neurotoxicity of the assembled Αβ fibrils was studied by the lactate dehydrogenase release assay (n = 6). Propofol (31.2 ± 4.7%) and thiopental (34.6 ± 10.5%) decreased GM1 expression on the cell surface through the γ-aminobutyric acid A receptor. The anesthetics inhibited Αβ fibril formation from soluble Αβ in cultured neurons. Moreover, propofol and thiopental suppressed GM1-induced fibril formation in a cell-free system (propofol, 75.8 ± 1.9%; thiopental, 83.6 ± 1.9%) and reduced the neurotoxicity of a mixture containing Aβ and GM1 liposomes (propofol, 35.3 ± 16.4%; thiopental, 21.3 ± 11.6%). Propofol and thiopental have direct and indirect inhibitory effects on Αβ fibrillogenesis.

Renal distribution of ganglioside GM3 in rat models of types 1 and 2 diabetes

Ganglioside GM3 is particularly abundant in the kidney tissue and is thought to play an important role in the maintenance of the charge-selective filtration barrier of glomeruli. Altered expression of ganglioside GM3 was pathologically related with glomerular hypertrophy occurring in diabetic human and rat kidneys. Considering the role of GM3 ganglioside in kidney function, the aim of this study was to determine the difference in expression of GM3 ganglioside in glomeruli and tubules using immunofluorescence microscopy both in rat models of types 1 and 2 diabetes mellitus. Diabetes was induced with streptozotocin (55 mg/kg for type 1 diabetes and 35 mg/kg for type 2 diabetes) injection to male Sprague-Dawley rats which were fed with normal pellet diet (type 1 diabetes) or high-fat diet (type 2 diabetes). Rats were sacrificed 2 weeks after diabetes induction, frozen renal sections were stained with primary antibody GM3(Neu5Ac) and visualized by secondary antibody coupled with Texas red. In addition, renal gangliosides GM3 were analyzed by high-performance thin-layer chromatography followed by GM3 immunostaining. Immunofluorescent microscopy detected 1.7-fold higher GM3 expression in tubules and 1.25-fold higher GM3 in glomeruli of type 1 diabetes mellitus compared with control group. Type 2 diabetes mellitus rats showed slight GM3 increase in whole kidney, unchanged GM3 in glomeruli, but significant higher GM3 expression in tubules, compared with control animals. Taking into consideration increased tubular GM3 content in both types of diabetes, we could hypothesize the role of GM3 in early pathogenesis of diabetic nephropathy.

Analysis of renal ganglioside GM3 distribution in rat models of type 1 and type 2 diabetes

Ganglioside GM3 is particularly abundant in the kidney tissue and is thought to play an important role in the maintenance of the charge‐selective filtration barrier of glomeruli. Considering the role of GM3 ganglioside in kidney function, the aim of this study was immunohistochemical analysis of renal GM3 distribution in rat models of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). Diabetes was induced with streptozotocin (55 mg/kg for T1DM, n=5; and 35 mg/kg for T2DM, n=5) injection to male Sprague‐Dawley rats weighing between 140 and 160 g which were fed with normal pellet diet (T1DM) or high‐fat diet (T2DM). Rats were sacrified two weeks after diabetes induction, frozen renal sections were stained with primary GM3 antibody and visualized by secondary antibody coupled with Texas‐Red. Immunofluorescent microscopy detected 1.7 fold higher GM3 expression in tubules and 1.25 fold higher GM3 in glomeruli of T1DM compared to control group. T2DM rats showed unchanged GM3 in glomeruli, but significant higher GM3 expression in tubules, compared to control animals. Given the known role of GM3 ganglioside in kidney function and our finding of increased tubular GM3 content in both types of diabetes, we could hypothesize the role of GM3 in early pathogenesis of diabetic nephropathy.This study was supported by Croatian Science Foundation.

Total synthesis of dansyl and biotin functionalized ganglioside GM3 by chemoenzymatic method

Ganglioside GM3, as well as other gangliosides, offers a variety of modifications in its sialic acid and ceramide moieties GM3 exhibits various types of important biological activities, due to the inability to effectively observe the trafficking of ganglioside GM3, developing sensitive research tools for specific monitoring of GM3 expression and activity is thus desirable. The total synthesis of a dansyl and biotin bifunctionalized fluorescent ganglioside GM3 were reported in this article. From lactose after 13 reaction steps, the compound of 2″-biotinoylaminoethyl-6-N-dansylamido-6-deoxy-β-D-galatopyranosyl-(1→4)-β-D-glucopy-ranoside was obtained in total yield of 16.2%. Sialylation of dansyl and biotin functionalized lactose by enzymatic method gave dansyl and biotin labeled ganglioside GM3. The fluorescent property of this compound was also investigated.

Ganglioside GM3 participates in the TGF-β1-induced epithelial–mesenchymal transition of human lens epithelial cells

TGF-β (transforming growth factor-β)-induced EMT (epithelial-mesenchymal transition) induces the proliferation and migration of the HLE (human lens epithelial) cells. Ganglioside GM3, simple sialic-acid-containing glycosphingolipids on mammalian cell membranes, regulates various pathological phenomena such as insulin resistance and tumour progression. However, the relationship between ganglioside GM3 and TGF-β-induced EMT in the HLE B-3 cells is poorly understood. In the present study we demonstrated that ganglioside GM3 was involved in TGF-β1-induced EMT in HLE B-3 cells. Our results indicated that the expression of ganglioside GM3 and GM3 synthase mRNA were significantly increased in TGF-β1-induced HLE B-3 cells. Reporter gene analysis also demonstrated that transcriptional activation of the GM3 synthase gene was regulated by Sp1 (specificity protein 1) in HLE B-3 cells upon TGF-β1 stimulation. Interestingly, the inhibition of ganglioside GM3 expression by d-PDMP [d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol] and GM3 synthase shRNA (short hairpin RNA) resulted significantly in the suppression of cell migration and EMT-related signalling in HLE B-3 cells stimulated by TGF-β. Furthermore, exogenous treatment of ganglioside GM3 rescued the expression of EMT molecules and cell migration suppressed by the depletion of ganglioside GM3in TGF-β1-induced HLE B-3 cells. We also found that ganglioside GM3 interacted with TGFβRs (TGF-β receptors) in TGF-β1-induced HLE B-3 cells. Taken together, these results suggest that ganglioside GM3 induced by TGF-β1 regulates EMT by potential interaction with TGFβRs.