GM3 Synthase Research Articles

Induction of Glycosphingolipid GM3 Expression by Valproic Acid Suppresses Cancer Cell Growth

Glycosphingolipid GM3, a known suppressor of epidermal growth factor receptor (EGFR) phosphorylation, inhibits cell proliferation. Valproic acid, conversely, is known as an up-regulator of GM3 synthase gene (ST3GAL5). To test the possibility that valproic acid could inhibit EGFR phosphorylation by increasing the level of GM3 in cells, we treated A431 epidermoid carcinoma cells with valproic acid and found that valproic acid treatment caused an about 6-fold increase in the GM3 level but only a marginal increase in the GM2 level in these cells and that the observed increase in GM3 level was valproic acid dose-dependent. Consistent with this observation, valproic acid treatment induced GM3 synthase gene expression by about 8-fold. Furthermore, phosphorylation of EGFR was reduced, and cell proliferation was inhibited following valproic acid treatment. Consistent with these results, transient expression of GM3 synthase gene in A431 cells also increased cellular level of GM3, reduced phosphorylation of EGFR, and inhibited cell proliferation. Treatment with l-phenyl-2-decanoylamino-3-morpholino-l-propanol, an inhibitor of glucosylceramide synthesis, decreased the cellular level of GM3 and reduced the inhibitory effects of valproic acid on EGFR phosphorylation and cell proliferation. These results suggested that induction of GM3 synthesis was enough to inhibit proliferation of cancer cells by suppressing EGFR activity. Valproic acid treatment similarly increased the GM3 level and reduced phosphorylation of EGFR in U87MG glioma cells and inhibited their proliferation. These results suggested that up-regulators of GM3 synthase gene, such as valproic acid, are potential suppressors of cancer cell proliferation.

Novel function of FAXDC2 in megakaryopoiesis.

FAXDC2 (fatty acid hydroxylase domain containing 2) is a member of the fatty acid hydroxylase superfamily. Given the important role of fatty acids in megakaryocytes, we have studied the role of this gene in the development of this lineage. Here we show that the expression of FAXDC2 is constantly elevated during megakaryocyte maturation. In contrast, FAXDC2 is significantly downregulated in acute myeloid leukemia and acute megakaryoblastic leukemia. Moreover, FAXDC2 overexpression promotes the differentiation of megakaryocytic cell lines and primary cells, whereas its knockdown disrupts their maturation. Mechanism study shows that FAXDC2 overexpression enhances extracellular signal-regulated kinase (ERK) signaling and increases RUNX1 (Runt-related transcription factor 1) expression. FAXDC2 also restores megakaryocytic differentiation in cells exposed to an ERK inhibitor or those expressing a dominant negative form of RUNX1. Finally, FAXDC2 overexpression leads to an increase in sphingolipid GM3 synthase, suggesting a potential role of FAXDC2 in lipid metabolism that increases ERK signaling and facilitates megakaryocyte differentiation. Together, these results show that FAXDC2 plays a novel role in development of megakaryocytes and its dysregulation may contribute to abnormal hematopoietic cell development in leukemia.

Quantification of monosialogangliosides in human plasma through chemical derivatization for signal enhancement in LC–ESI-MS

Gangliosides are found in abundance in the central nervous system of vertebrates. Their metabolic disruption and dysfunction are associated with various neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. In order to improve our understanding of the etiology of these diseases, analytical ganglioside assays with sufficient specificity and sensitivity in relevant biological matrices are required. In the present work we have developed and validated a reverse-phase ultra-performance liquid chromatography (UPLC)/tandem mass spectrometry (MS) method for determining monosialogangliosides GM1, GM2, and GM3 present in human plasma. Compared with our previous method, this method enhanced, by 15 fold, MS responses of the analytes by employing 2-(2-Pyridilamino)-ethylamine (PAEA) & 4-(4, 6-Dimethoxy-1, 3, 5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM)-based derivatization. The analytes and internal standards were derivatized with PAEA&DMTMM after extraction from plasma using a protein precipitation procedure. They were then purified using liquid–liquid partitioning. When the samples were then analyzed by UPLC-MS/MS with a multiple reaction monitoring (MRM) mode, we achieved superior sensitivity and specificity. This method was evaluated for extraction recovery, calibration linearity, precision, accuracy, and lower limit of quantification (LLOQ). The validated method was successfully applied to monitor monosialoganglioside levels in the plasma from patients with GM3 synthase deficiency. With significantly increased sensitivity, we have, for the first time, detected a significant amount of GM3 in the affected patients.

Expression analysis of 0-series gangliosides in human cancer cell lines with monoclonal antibodies generated using knockout mice of ganglioside synthase genes.

Some gangliosides, sialic acid-containing glycosphingolipids, have been considered as tumor-associated antigens. GD1α or a GD1α synthase gene ST6GalNAc5 was reported to be involved in the metastasis of murine lymphomas or human breast cancers, respectively. But expression patterns of 0-series gangliosides GD1α and its precursor GM1b in human cancers have not yet been investigated mainly due to lack of specific antibodies. We established specific monoclonal antibodies (mAbs) reactive with GD1α or GM1b using gangliosides from brain tissues of GM3 synthase (St3gal5)-deficient mice as immunogens. We used GM2/GD2 synthase (B4galnt1)-deficient mice to immunize by liposomes embedded with GD1α or acidic glycolipid fractions from brain of St3gal5-deficient mice. Specificities of established mAbs as analyzed by enzyme-linked immunosorbent assay and thin-layer chromatography-immunostaining were very high among various gangliosides. Increased expression of GD1α and reduced GM1b in the St6galnac5 cDNA-transfected RAW117 cell line also substantiated the specificities of two mAbs. Then, we analyzed expression of GD1α and GM1b, and of relevant glycosyltransferase genes in various human cancer cell lines using generatedanti-GD1α mAb 122 or anti-GM1b mAb MR155A-7. A few human cancer cell lines showed significant expression of these gangliosides with reasonable expression of relevant glycosyltransferase genes.

Early growth and development impairments in patients with ganglioside GM3 synthase deficiency.

Ganglioside GM3 synthase is a key enzyme involved in the biosynthesis of gangliosides. GM3 synthase deficiency (GSD) causes a complete absence of GM3 and all downstream biosynthetic derivatives. The individuals affected by this disorder manifest severe irritability, intractable seizures and profound intellectual disability. However, we have found that most newborns seem symptom-free for a period of time after birth. In order to further understand the onset of the disease, we investigated the early growth and development of patients with this condition through this study. We compared 37 affected individuals with their normal siblings and revealed that all children with GSD had relatively normal intrauterine growth and development, as their weight, length and head circumference were similar to their normal siblings at birth. However, the disease progresses quickly after birth and causes significant constitutional impairments of growth and development by 6 months of age. Neither breastfeeding nor gastrostomy tube placement made significant difference on growth and development as all groups of patients showed the similar pattern. We conclude that GSD causes significant postnatal growth and developmental impairments and the amount of gangliosides in breast milk and general nutritional intervention do not seem to alter these outcomes.

Ganglioside GM3 synthase depletion reverses neuropathic pain and small fiber neuropathy in diet-induced diabetic mice

BackgroundSmall fiber neuropathy is a well-recognized complication of type 2 diabetes and has been shown to be responsible for both neuropathic pain and impaired wound healing. In previous studies, we have demonstrated that ganglioside GM3 depletion by knockdown of GM3 synthase fully reverses impaired wound healing in diabetic mice. However, the role of GM3 in neuropathic pain and small fiber neuropathy in diabetes is unknown.PurposeDetermine whether GM3 depletion is able to reverse neuropathic pain and small fibers neuropathy and the mechanism of the reversal.ResultsWe demonstrate that GM3 synthase knockout and the resultant GM3 depletion rescues the denervation in mouse footpad skin and fully reverses the neuropathic pain in diet-induced obese diabetic mice. In cultured dorsal root ganglia from diet-induced diabetic mice, GM3 depletion protects against increased intracellular calcium influx in vitro.ConclusionsThese studies establish ganglioside GM3 as a new candidate responsible for neuropathic pain and small fiber neuropathy in diabetes. Moreover, these observations indicate that systemic or topically applied interventions aimed at depleting GM3 may improve both the painful neuropathy and the wound healing impairment in diabetes by protecting against nerve end terminal degeneration, providing a disease-modifying approach to this common, currently intractable medical issue.

Serum Deprivation-Induced Human GM3 Synthase (hST3Gal V) Gene Expression Is Mediated by Runx2 in Human Osteoblastic MG-63 Cells.

Serum deprivation (SD) is well known to induce G0/G1 cell cycle arrest and apoptosis in various cells. In the present study, we firstly found that SD could induce G1 arrest and the differentiation of human osteoblastic MG-63 cells, as evidenced by the increase of osteoblastic differentiation markers, such as bone morphogenetic protein-2 (BMP-2), osteocalcin and runt-related transcription factor 2 (Runx2). In parallel, gene expression of human GM3 synthase (hST3Gal V) catalyzing ganglioside GM3 biosynthesis was upregulated by SD in MG-63 cells. The 5′-flanking region of the hST3Gal V gene was functionally characterized to elucidate transcriptional regulation of hST3Gal V in SD-induced MG-63 cells. Promoter analysis using 5′-deletion constructs of the hST3Gal V gene demonstrated that the −432 to −177 region functions as the SD-inducible promoter. Site-directed mutagenesis revealed that the Runx2 binding sites located side-by-side at positions −232 and −222 are essential for the SD-induced expression of hST3Gal V in MG-63 cells. In addition, the chromatin immunoprecipitation assay also showed that Runx2 specifically binds to the hST3Gal V promoter region containing Runx2 binding sites. These results suggest that SD triggers upregulation of hST3Gal V gene expression through Runx2 activation by BMP signaling in MG-63 cells.

Sphingolipids modulate the epithelial-mesenchymal transition in cancer.

Sphingolipids modulate the epithelial-mesenchymal transition in cancer.

SiRNA-based spherical nucleic acids reverse impaired wound healing in diabetic mice by ganglioside GM3 synthase knockdown

Spherical nucleic acid (SNA) gold nanoparticle conjugates (13-nm-diameter gold cores functionalized with densely packed and highly oriented nucleic acids) dispersed in Aquaphor have been shown to penetrate the epidermal barrier of both intact mouse and human skin, enter keratinocytes, and efficiently down-regulate gene targets. ganglioside-monosialic acid 3 synthase (GM3S) is a known target that is overexpressed in diabetic mice and responsible for causing insulin resistance and impeding wound healing. GM3S SNAs increase keratinocyte migration and proliferation as well as insulin and insulin-like growth factor-1 (IGF1) receptor activation under both normo- and hyperglycemic conditions. The topical application of GM3S SNAs (50 nM) to splinted 6-mm-diameter full-thickness wounds in diet-induced obese diabetic mice decreases local GM3S expression by >80% at the wound edge through an siRNA pathway and fully heals wounds clinically and histologically within 12 d, whereas control-treated wounds are only 50% closed. Granulation tissue area, vascularity, and IGF1 and EGF receptor phosphorylation are increased in GM3S SNA-treated wounds. These data capitalize on the unique ability of SNAs to naturally penetrate the skin and enter keratinocytes without the need for transfection agents. Moreover, the data further validate GM3 as a mediator of the delayed wound healing in type 2 diabetes and support regional GM3 depletion as a promising therapeutic direction.

Protein composition and movements of membrane swellings associated with primary cilia.

Dysfunction of many ciliary proteins has been linked to a list of diseases, from cystic kidney to obesity and from hypertension to mental retardation. We previously proposed that primary cilia are unique communication organelles that function as microsensory compartments that house mechanosensory molecules. Here we report that primary cilia exhibit membrane swellings or ciliary bulbs, which based on their unique ultrastructure and motility, could be mechanically regulated by fluid-shear stress. Together with the ultrastructure analysis of the swelling, which contains monosialodihexosylganglioside (GM3), our results show that ciliary bulb has a distinctive set of functional proteins, including GM3 synthase (GM3S), bicaudal-c1 (Bicc1), and polycystin-2 (PC2). In fact, results from our cilia isolation demonstrated for the first time that GM3S and Bicc1 are members of the primary cilia proteins. Although these proteins are not required for ciliary membrane swelling formation under static condition, fluid-shear stress induced swelling formation is partially modulated by GM3S. We therefore propose that the ciliary bulb exhibits a sensory function within the mechano-ciliary structure. Overall, our studies provided an important step towards understanding the ciliary bulb function and structure.

Ganglioside GM3 is essential for the structural integrity and function of cochlear hair cells.

GM3 synthase (ST3GAL5) is the first biosynthetic enzyme of a- and b-series gangliosides. Patients with GM3 synthase deficiency suffer severe neurological disability and deafness. Eight children (ages 4.1 ± 2.3 years) homozygous for ST3GAL5 c.694C>T had no detectable GM3 (a-series) or GD3 (b-series) in plasma. Their auditory function was characterized by the absence of middle ear muscle reflexes, distortion product otoacoustic emissions and cochlear microphonics, as well as abnormal auditory brainstem responses and cortical auditory-evoked potentials. In St3gal5(-/-) mice, stereocilia of outer hair cells showed signs of degeneration as early as postnatal Day 3 (P3); thereafter, blebs devoid of actin or tubulin appeared at the region of vestigial kinocilia, suggesting impaired vesicular trafficking. Stereocilia of St3gal5(-/-) inner hair cells were fused by P17, and protein tyrosine phosphatase receptor Q, normally linked to myosin VI at the tapered base of stereocilia, was maldistributed along the cell membrane. B4galnt1(-/-) (GM2 synthase-deficient) mice expressing only GM3 and GD3 gangliosides had normal auditory structure and function. Thus, GM3-dependent membrane microdomains might be essential for the proper organization and maintenance of stereocilia in auditory hair cells.

Zeb1 affects epithelial cell adhesion by diverting glycosphingolipid metabolism.

This study proposes that the transcription factor Zeb1 modulates epithelial cell adhesion by diverting glycosphingolipid metabolism. Zeb1 promotes expression of a-series glycosphingolipids via regulating expression of GM3 synthase (St3gal5), which mechanistically involves Zeb1 binding to the St3gal5 promoter as well as suppressing microRNA-mediated repression of St3gal5. Functionally, the repression of St3gal5 suffices to elevate intercellular adhesion and expression of distinct junction-associated proteins, reminiscent of knockdown of Zeb1. Conversely, overexpressing St3gal5 sensitizes cells towards TGF-β1-induced disruption of cell-cell interaction and partially antagonizes elevation of intercellular adhesion imposed by Zeb1 knockdown. These results highlight a direct connection of glycosphingolipid metabolism and epithelial cell adhesion via Zeb1.

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.

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.

Molecular subtyping of metastatic melanoma based on cell ganglioside metabolism profiles.

BackgroundIn addition to alterations concerning the expression of oncogenes and onco-suppressors, melanoma is characterized by the presence of distinctive gangliosides (sialic acid carrying glycosphingolipids). Gangliosides strongly control cell surface dynamics and signaling; therefore, it could be assumed that these alterations are linked to modifications of cell behavior acquired by the tumor. On these bases, this work investigated the correlations between melanoma cell ganglioside metabolism profiles and the biological features of the tumor and the survival of patients.MethodsMelanoma cell lines were established from surgical specimens of AJCC stage III and IV melanoma patients. Sphingolipid analysis was carried out on melanoma cell lines and melanocytes through cell metabolic labeling employing [3-3H]sphingosine and by FACS. N-glycolyl GM3 was identified employing the 14 F7 antibody. Gene expression was assayed by Real Time PCR. Cell invasiveness was assayed through a Matrigel invasion assay; cell proliferation was determined through the soft agar assay, MTT, and [3H] thymidine incorporation. Statistical analysis was performed using XLSTAT software for melanoma hierarchical clustering based on ganglioside profile, the Kaplan-Meier method, the log-rank (Mantel-Cox) test, and the Mantel-Haenszel test for survival analysis.ResultsBased on the ganglioside profiles, through a hierarchical clustering, we classified melanoma cells isolated from patients into three clusters: 1) cluster 1, characterized by high content of GM3, mainly in the form of N-glycolyl GM3, and GD3; 2) cluster 2, characterized by the appearance of complex gangliosides and by a low content of GM3; 3) cluster 3, which showed an intermediate phenotype between cluster 1 and cluster 3. Moreover, our data demonstrated that: a) a correlation could be traced between patients’ survival and clusters based on ganglioside profiles, with cluster 1 showing the worst survival; b) the expression of several enzymes (sialidase NEU3, GM2 and GM1 synthases) involved in ganglioside metabolism was associated with patients’ survival; c) melanoma clusters showed different malignant features such as growth in soft agar, invasiveness, expression of anti-apoptotic proteins.ConclusionsGanglioside profile and metabolism is strictly interconnected with melanoma aggressiveness. Therefore, the profiling of melanoma gangliosides and enzymes involved in their metabolism could represent a useful prognostic and diagnostic tool.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-560) contains supplementary material, which is available to authorized users.

The ganglioside GM3 is associated with cisplatin-induced apoptosis in human colon cancer cells.

Cisplatin (cis-diamminedichloroplatinum, CDDP) is a well-known chemotherapeutic agent for the treatment of several cancers. However, the precise mechanism underlying apoptosis of cancer cells induced by CDDP remains unclear. In this study, we show mechanistically that CDDP induces GM3-mediated apoptosis of HCT116 cells by inhibiting cell proliferation, and increasing DNA fragmentation and mitochondria-dependent apoptosis signals. CDDP induced apoptosis within cells through the generation of reactive oxygen species (ROS), regulated the ROS-mediated expression of Bax, Bcl-2, and p53, and induced the degradation of the poly (ADP-ribosyl) polymerase (PARP). We also checked expression levels of different gangliosides in HCT116 cells in the presence or absence of CDDP. Interestingly, among the gangliosides, CDDP augmented the expression of only GM3 synthase and its product GM3. Reduction of the GM3 synthase level through ectopic expression of GM3 small interfering RNA (siRNA) rescued HCT116 cells from CDDP-induced apoptosis. This was evidenced by inhibition of apoptotic signals by reducing ROS production through the regulation of 12-lipoxigenase activity. Furthermore, the apoptotic sensitivity to CDDP was remarkably increased in GM3 synthase-transfected HCT116 cells compared to that in controls. In addition, GM3 synthase-transfected cells treated with CDDP exhibited an increased accumulation of intracellular ROS. These results suggest the CDDP-induced oxidative apoptosis of HCT116 cells is mediated by GM3.

Ganglioside GM3 is required for caffeic acid phenethyl ester-induced megakaryocytic differentiation of human chronic myelogenous leukemia K562 cells.

The human chronic myelogenous cell line K562 has been used extensively as a model for the study of leukemia differentiation. We show here that treatment of K562 cells with caffeic acid phenethyl ester (CAPE) induced a majority of cells to differentiate towards the megakaryocytic lineage. Microscopy analysis showed that K562 cells treated with CAPE exhibited characteristic features of physiological megakaryocytic differentiation, including the presence of vacuoles and demarcation membranes. Differentiation of K562 cells treated with CAPE was also accompanied by a net increase in megakaryocytic markers. The transcriptional activity of lactosylceramide α-2,3-sialyltransferase (GM3 synthase) and synthesis of ganglioside GM3 were increased by CAPE treatment. The promoter analysis of GM3 synthase demonstrated that CAPE induced the expression of GM3 synthase mRNA via activation of the cAMP response element-binding protein (CREB), transcription factor in nucleus. Interestingly, the inhibition of ganglioside GM3 synthesis by D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propranol (D-PDMP) and GM3 synthase-siRNA blocked the CAPE-induced expression of the megakaryocytic markers and differentiation of K562 cells. Taken together, these results suggest that CAPE induces ganglioside GM3-mediated megakaryocytic differentiation of human chronic myelogenous cells.

Ganglioside GM3 Depletion Reverses Impaired Wound Healing in Diabetic Mice by Activating IGF-1 and Insulin Receptors

BackgroundGanglioside GM3 mediates adipocyte insulin resistance, but the role of GM3 in diabetic wound healing, a major cause of morbidity, is unclear.PurposeDetermine whether GM3 depletion promotes diabetic wound healing and directly activates keratinocyte insulin pathway signaling.ResultsGM3 synthase (GM3S) expression is increased in human diabetic foot skin, ob/ob and diet-induced obese diabetic mouse skin, and mouse keratinocytes exposed to increased glucose. GM3S knockout in diet-induced obese mice prevents the diabetic wound healing defect. Keratinocyte proliferation, migration, and activation of insulin receptor (IR) and insulin growth factor-1 receptor (IGF-1R) are suppressed by excess glucose in wild type cells, but increased in GM3S −/− keratinocytes with supplemental glucose. Co-immunoprecipitation of IR, IR substrate-1 (IRS-1), and IGF-1R, and increased IRS-1 and Akt phosphorylation accompany receptor activation. GM3 supplementation or inhibition of IGF-1R or PI3K reverses the increased migration of GM3S−/− keratinocytes, whereas IR knockdown only partially suppresses migration.ConclusionsCutaneous GM3 accumulation may participate in the impaired wound healing of diet-induced diabetes by suppressing keratinocyte insulin/IGF-1 axis signaling. Strategies to deplete GM3S/GM3 may improve diabetic wound healing.

Expression of leukocyte adhesion-related glycosyltransferase genes in acute coronary syndrome patients.

Acute coronary syndrome (ACS) is caused by destabilization and rupture of atherosclerotic plaque in the coronary artery via mechanisms affecting leukocyte signaling, rolling, adhesion, extravasation and inflammation-promoting factors. The majority of cellular communication takes place on the membrane surface that is covered with glycoproteins and glycolipids synthesized by glycosyltransferases. The aim of this study was to determine the mRNA expression of leukocyte adhesion-related glycosyltransferases in patients during the onset and the chronic phase of ACS and to compare the expression with matching subjects without coronary disease. The study included 26 ACS patients and 26 ACS-free matched-pair controls. Blood samples were collected at the time of hospital admittance and 8days later. Expression analysis of six fucosyltransferases and six sialyltransferases was performed by a real-time polymerase chain reaction. At the time of admittance ACS subjects had lower expression levels of FUT4, ST6GalNac4, ST6Gal1 and GM3 synthase (p<0.05) than the control subjects, and moreover, after 8days down-regulation of FUT7 and ST6GalNac3 was also observed (p<0.05). When compared to the initial gene expression, after treatment and stabilization of ACS subjects, FUT7, ST6GalNac2 and ST6GalNac3 were down-regulated, whereas ST6GalNac1 was up-regulated. Expression levels of FUT7, ST6GalNac1, ST6GalNac2 and ST6GalNac3 were predicted by several drugs and medical history. Expression of glycosyltransferase genes differs in ACS and control subjects. During the course of the ACS study we established further changes in gene expression levels. Medical history was predictive of gene expression levels while drugs were shown to modulate expression levels.

Inhibition of GM3 synthase attenuates neuropathology of Niemann-Pick disease Type C. by affecting sphingolipid metabolism.

In several lysosomal storage disorders, including Niemann-Pick disease Type C (NP-C), sphingolipids, including glycosphingolipids, particularly gangliosides, are the predominant storage materials in the brain, raising the possibility that accumulation of these lipids may be involved in the NP-C neurodegenerative process. However, correlation of these accumulations and NP-C neuropathology has not been fully characterized. Here we derived NP-C mice with complete and partial deletion of the Siat9 (encoding GM3 synthase) gene in order to investigate the role of ganglioside in NP-C pathogenesis. According to our results, NPC mice with homozygotic deletion of GM3 synthase exhibited an enhanced neuropathological phenotype and died significantly earlier than NP-C mice. Notably, in contrast to complete depletion, NP-C mice with partial deletion of the GM3 synthase gene showed ameliorated NP-C neuropathology, including motor disability, demyelination, and abnormal accumulation of cholesterol and sphingolipids. These findings indicate the crucial role of GM3 synthesis in the NP-C phenotype and progression of CNS pathologic abnormality, suggesting that well-controlled inhibition of GM3 synthesis could be used as a therapeutic strategy.