Roles of gangliosides in mouse embryogenesis and embryonic stem cell differentiation

Antiviral Defence Mechanisms during Early Mammalian Development

The type-I interferon (IFN) response constitutes the major innate immune pathway against viruses in mammals. Despite its critical importance for antiviral defence, this pathway is inactive during early embryonic development. There seems to be an incompatibility between the IFN response and pluripotency, the ability of embryonic cells to develop into any cell type of an adult organism. Instead, pluripotent cells employ alternative ways to defend against viruses that are typically associated with safeguard mechanisms against transposable elements. The absence of an inducible IFN response in pluripotent cells and the constitutive activation of the alternative antiviral pathways have led to the hypothesis that embryonic cells are highly resistant to viruses. However, some findings challenge this interpretation. We have performed a meta-analysis that suggests that the susceptibility of pluripotent cells to viruses is directly correlated with the presence of receptors or co-receptors for viral adhesion and entry. These results challenge the current view of pluripotent cells as intrinsically resistant to infections and raise the fundamental question of why these cells have sacrificed the major antiviral defence pathway if this renders them susceptible to viruses.

Disordered testosterone transport in mice lacking the ganglioside GM2/GD2 synthase gene

Genetic disruption of glycosyltransferases has provided clear information on the roles of their reaction products in the body. Our group has studied the function of glycosphingolipids by genetic engineering of glycosyltransferases in cell culture and in mice, which has demonstrated both expected and unexpected results. Among these findings, aspermatogenesis in ganglioside GM2/GD2 synthase knockout mice was one of the most surprising and intriguing results. There were no sperms in testis, and multinuclear giant cells were detected instead of spermatids. Although serum levels of testosterone in the male mice were extremely low, testosterone accumulated in the interstitial tissues, including Leydig cells, and seemed not to be transferred into the seminiferous tubules or vascular cavity from Leydig cells. This was considered to be the cause of aspermatogenesis and low serum levels of testosterone. Patients with a mutant GM2/GD2 synthase gene (SPG26) showed similar clinical signs, not only in terms of the neurological aspects, but also in the male reproductive system. The mechanisms for testosterone transport by gangliosides are discussed here based on our own results and reports from other laboratories.

Role of sphingolipid metabolites in the homeostasis of steroid hormones and the maintenance of testicular functions

With the acceleration of life pace and the increase of work pressure, the problem of male infertility has become a social problem of general concern. Sphingolipids are important regulators of many cellular processes like cell differentiation and apoptosis, which are ubiquitously expressed in all mammalian cells. Various sphingolipid catabolic enzymes can generate multiple sphingolipids like sphingosine-1-phosphate and sphingomyelin. Present studies have already demonstrated the role of steroid hormones in the physiological processes of reproduction and development through hypothalamus-pituitary-gonad axis, while recent researches also found not only sphingolipids can modulate steroid hormone secretion, but also steroid hormones can control sphingolipid metabolites, indicating the role of sphingolipid metabolites in the homeostasis of steroid hormones. Furthermore, sphingolipid metabolites not only contribute to the regulation of gametogenesis, but also mediate damage-induced germ apoptosis, implying the role of sphingolipid metabolites in the maintenance of testicular functions. Together, sphingolipid metabolites are involved in impaired gonadal function and infertility in males, and further understanding of these bioactive sphingolipids will help us develop new therapeutics for male infertility in the future.

Gangliosides and Their Role in Multilineage Differentiation of Mesenchymal Stem Cells

Gangliosides (GGs) are a glycolipid class present on Mesenchymal Stem Cells (MSCs) surfaces with a critical appearance role in stem cell differentiation, even though their mechanistic role in signaling and differentiation remains largely unknown. This review aims to carry out a critical analysis of the predictive role of gangliosides as specific markers of the cellular state of undifferentiated and differentiated MSCs, towards the osteogenic, chondrogenic, neurogenic, and adipogenic lineage. For this reason, we analyzed the role of GGs during multilineage differentiation processes of several types of MSCs such as Umbilical Cord-derived MSCs (UC-MSCs), Bone Marrow-derived MSCs (BM-MSCs), Dental Pulp derived MSCs (DPSCs), and Adipose derived MSCs (ADSCs). Moreover, we examined the possible role of GGs as specific cell surface markers to identify or isolate specific stem cell isotypes and their potential use as additional markers for quality control of cell-based therapies.

Differential Ganglioside and Cholesterol Depletion by Various Cyclodextrin Derivatives and Their Effect on Synaptosomal Glutamate Release

Gangliosides are glycosphingolipids of the plasma membrane and are highly enriched in the nervous system where they play a vital role in normal cell functions. Furthermore, several studies suggest their potential involvement in the pathogenesis of neurological conditions. Since cyclodextrins (CDs) can form inclusion complexes with various lipids, methylated beta-CDs are widely used in biomedical research to extract cholesterol from the membrane and study its cellular role. Despite CDs being known to interact with other membrane lipid components, their effect on gangliosides is poorly characterized. The aim of this research was to investigate the effect of dimethyl-beta-cyclodextrin (DIMEB), hydroxypropyl-beta-cyclodextrin (HPBCD), randomly methylated-alpha-cyclodextrin (RAMEA), and hydroxypropyl-alpha-cyclodextrin (HPACD) on ganglioside and cholesterol levels in rat brain synaptosomes. Their effect on membrane integrity and viability was also assessed. We examined the role of lipid depletion by CDs on the release of the major excitatory neurotransmitter, glutamate. Selective concentration range for cholesterol depletion was only found with HPBCD, but not with DIMEB. Selective depletion of gangliosides was achieved by both RAMEA and HPACD. The inhibition of stimulated glutamate release upon ganglioside depletion was found, suggesting their potential role in neurotransmission. Our study highlights the importance of the characterization of the lipid depleting capability of different CDs.

Sphingolipids and their role in health and disease in the central nervous system

Sphingolipids (SLs) are lipids derived from sphingosine, and their metabolism involves a broad and complex network of reactions. Although SLs are widely distributed in the body, it is well known that they are present in high concentrations within the central nervous system (CNS). Under physiological conditions, their abundance and distribution in the CNS depend on brain development and cell type. Consequently, SLs metabolism impairment may have a significant impact on the normal CNS function, and has been associated with several disorders, including sphingolipidoses, Parkinson's, and Alzheimer's. This review summarizes the main SLs characteristics and current knowledge about synthesis, catabolism, regulatory pathways, and their role in physiological and pathological scenarios in the CNS.

Genome-wide selective detection of Mile red-bone goat using next-generation sequencing technology

The ecotype population of goats (Capra hircus) was created by long-term artificial selection and natural adaptation. Mile red-bone goat is an indigenous breed with visible red bones, and its special bone structure has received extensive attention. This study aimed to identify genetic variants and candidate genes associated with specific bone phenotypes using next-generation sequencing technology (NGS). The results revealed that 31,828,206 single nucleotide polymorphisms (SNPs) were obtained from 72 goats (20 Mile red-bone goats and 52 common goats) by NGS. A total of 100 candidate genes were identified on the basis top 1% window interaction from nucleotide diversity (π), π ratio (π A/π B), and pairwise fixation index (F ST). Exactly 77 known signaling pathways were enriched. Specifically, three coding genes (NMNAT2, LOC102172983, and PNLIP) were annotated in the vitamin metabolism signaling pathways, and NCF2 was annotated to the osteoclast (OC) differentiation pathway. Furthermore, 5862 reliable copy number variations (CNVs) were obtained, and 14 and 24 genes were annotated with the top 1‰ CNV based on F ST (>0.490) and V ST (>0.527), respectively. Several pathways related to bone development and metabolism of exogenous substances in vivo, including calcium signaling pathway, OC differentiation, and glycerophospholipid metabolism, were annotated. Specifically, six genes from 19 candidate CNVs, which were obtained by interaction of the top 1‰ CNVs with F ST and V ST, were annotated to mucin-type O-glycan biosynthesis and metabolic pathways. Briefly, the results implied that pseudopurpurin and specific genetic variants work together to contribute to the red-bone color and specific bone structure of Mile red-bone goat. This study is helpful to understanding the genetic basis of the unique bone phenotype of Mile red-bone goats.

Inhibition of Ganglioside Synthesis Suppressed Liver Cancer Cell Proliferation through Targeting Kinetochore Metaphase Signaling

The incidence and mortality of liver cancer, mostly hepatocellular carcinoma (HCC), have increased during the last two decades, partly due to persistent inflammation in the lipid-rich microenvironment associated with lifestyle diseases, such as obesity. Gangliosides are sialic acid-containing glycosphingolipids known to be important in the organization of the membrane and membrane protein-mediated signal transduction. Ganglioside synthesis is increased in several types of cancers and has been proposed as a promising target for cancer therapy. Here, we provide evidence that ganglioside synthesis was increased in the livers of an animal model recapitulating the features of activation and expansion of liver progenitor-like cells and liver cancer (stem) cells. Chemical inhibition of ganglioside synthesis functionally suppressed proliferation and sphere growth of liver cancer cells, but had no impact on apoptotic and necrotic cell death. Proteome-based mechanistic analysis revealed that inhibition of ganglioside synthesis downregulated the expression of AURKA, AURKB, TTK, and NDC80 involved in the regulation of kinetochore metaphase signaling, which is essential for chromosome segregation and mitotic progression and probably under the control of activation of TP53-dependent cell cycle arrest. These data suggest that targeting ganglioside synthesis holds promise for the development of novel preventive/therapeutic strategies for HCC treatment.

S1P-lyase deficiency uncouples ganglioside formation - Potential contribution to tumorigenic capacity

Sphingosine-1-phosphate (S1P) is not only a catabolic intermediate of all sphingolipids but also an evolutionary conserved bioactive lipid with critical functions in cell survival, differentiation, and migration as well as in immunity and angiogenesis. S1P-lyase (SGPL1) irreversibly cleaves S1P in the final step of sphingolipid catabolism. As sphingoid bases and their 1-phosphates are not only metabolic intermediates but also highly bioactive lipids that modulate a wide range of physiological processes, it would be predicted that their elevation might induce adjustments in other facets of sphingolipid metabolism and/or alter cell behavior. We actually found in a previous study that in terminally differentiated neurons SGPL1 deficiency increases sphingolipid formation via recycling at the expense of de novo synthesis. We now investigated whether and how SGPL1 deficiency affects the metabolism of (glyco)sphingolipids in mouse embryonic fibroblasts (MEFs). According to our previous experiments in neurons, we found a strong accumulation of S1P in SGPL1-deficient MEFs. Surprisingly, a completely different situation arose as we analyzed sphingolipid metabolism in this non-differentiated cell type. The production of biosynthetic precursors of complex glycosphingolipids including ceramide, glucosylceramide and also ganglioside GM3 via de novo synthesis and recycling pathway was substantially increased whereas the amount of more complex gangliosides dropped significantly.

Exogenous Ganglioside GT1b Enhances Porcine Oocyte Maturation, Including the Cumulus Cell Expansion and Activation of EGFR and ERK1/2 Signaling

Ganglioside GT1b is well-known for its role in cytokine production and in activating epidermal growth factor receptor (EGFR)-mediated signaling pathways in cancer cells. However, there are no reports that clearly elucidate the role of GT1b in EGFR-mediated signaling pathways in porcine oocytes during the process of in vitro maturation (IVM). In this study, we investigated the role of GT1b in EGFR-mediated activation of the ERK1/2 pathway in porcine cumulus-oocyte complexes (COCs) at 44 h of IVM. Our data show that expression of the ST3GAL2 protein significantly increased in porcine COCs at 44 h irrespective of treatment with EGF. Meiotic maturation and mRNA levels of factors (HAS2, TNFAIP6, and PTX3) related to cumulus cell expansion significantly increased in COCs treated with 2 μM GT1b during IVM in the absence of EGF. They also increased in COCs treated with EGF/GT1b as compared to that in the other groups. Interestingly, protein levels of EGFR, phospho-EGFR, ERK1/2, and phospho-ERK1/2 dramatically increased in COCs treated with EGF/GT1b. Moreover, the rate of fertilization and the developmental competence of blastocyst were significantly higher in EGF/GT1b-treated COCs. Taken together, these results suggest that exogenous GT1b improves meiotic maturation and cumulus cell expansion in porcine COCs via activation of EGFR-mediated ERK1/2 signaling.

Comprehensive Profiling of Surface Gangliosides Extracted from Various Cell Lines by LC-MS/MS

Gangliosides act as a surface marker at the outer cellular membrane and play key roles in cancer cell invasion and metastasis. Despite the biological importance of gangliosides, they have been still poorly characterized due to the lack of effective analytical tools. Herein, we performed molecular profiling and structural elucidation of intact gangliosides in various cell lines including CFPAC1, A549, NCI-H358, MCF7, and Caski. We identified and quantified a total of 76 gangliosides on cell membrane using C18 LC-MS/MS. Gangliosides found in each cell line exhibited high complexity and diversity both qualitatively and quantitatively. The most abundant species was GM3(d34:1) in CFPAC1, NCI-H358, and MCF7, while GM2(d34:1) and GM1(d34:1) were major components in A549 and Caski, respectively. Notably, glycan moieties showed more diversity between cancer cell lines than ceramide moieties. In addition, noncancerous pancreatic cell line (hTERT/HPNE) could be distinguished by gangliosides containing different levels of sialic acid compared with cancerous pancreatic cell line (CFPAC1). These results clearly demonstrated the feasibility of our analytical platform to comprehensive profile of cell surface gangliosides for identifying cell types and subgrouping cancer cell types.

Ganglioside GM3 induces cumulus cell apoptosis through inhibition of epidermal growth factor receptor-mediated PI3K/AKT signaling pathways during in vitro maturation of pig oocytes

Gangliosides are components of the mammalian plasma membrane that help regulate receptor signaling. Ganglioside GM3, for example, plays an important role in initiating apoptosis in cancer cells; however, physiological roles for GM3 in normal processes, such as during pig oocyte maturation, are not clear. The aim of this study was to investigate the functional link between GM3 and cellular apoptosis in porcine cumulus-oocyte-complexes (COCs) during in vitro maturation. Our results indicated that denuded oocytes possess less ST3GAL5, a GM3-synthesizing enzyme, than cumulus cells or COCs after 44 hr of in vitro maturation. GM3 also affected the meiotic maturation of cultured pig oocytes, as evaluated by orcein staining. In vitro treatment of COCs with exogenous GM3 also reduced cumulus cell expansion, the proportion of meiotic maturation, and increased cumulus cell transcription of PTX3, TNFAIP6, and HAS2. Interestingly, GM3 treatment reduced the expression of Epidermal growth factor receptor (EGFR)-mediated Phosphoinositide 3-kinase/AKT signaling proteins in COCs in a concentration-dependent manner, instead increasing the abundance of pro-apoptotic factors such as AIF, activated Caspase 9, cleaved PARP1, and Caspase 3 were. Thus, GM3 might affect porcine oocyte maturation via suppression of EGFR-mediated PI3K/AKT signaling and/or induction of apoptosis during in vitro maturation.

Ganglioside GD1a promotes oocyte maturation, furthers preimplantation development, and increases blastocyst quality in pigs

Gangliosides are key lipid molecules required for the regulation of cellular processes such as proliferation, differentiation, and cell signaling, including signaling of epidermal growth factor receptor (EGFR). Epidermal growth factor (EGF) has long been considered a potential regulator of meiotic and cytoplasmic maturation in mammalian oocytes. However, there is no report on the direct effect of ganglioside GD1a in porcine oocyte maturation. In this study, we first investigated a functional link between GD1a and meiotic maturation during in vitro maturation (IVM) of porcine embryos. Moreover, we confirmed the effect of exogenous GD1a treatment on blastocyst development, quality, and fertilization rate in early embryonic development. First, we observed that the protein level of ST3GAL2, a GD1a synthesizing enzyme, significantly increased (P < 0.01) in cumulus-oocyte-complexes (COCs) during IVM progress. The proportion of arrested germinal vesicles (GV) increased in oocytes treated with EGF+GD1a (41.6 ± 1.5%) at the IVM I stage. Upon completion of meiotic maturation, the proportion of metaphase II (M II) was significantly higher (P < 0.05) in the EGF+GD1a (89.9 ± 3.6%) treated group. After IVF, the percentage of penetrated oocytes was significantly higher (P < 0.05) in the EGF+GD1a (89.1 ± 2.3%) treated group than in the control group. Furthermore, exogenous GD1a treatment improved the developmental competence and quality of blastocysts during preimplantation embryo development stage. These results suggest that ganglioside GD1a may play an important role in IVM mechanisms of porcine maturation capacity. Furthermore, our findings will be helpful for better promoting the embryo development and blastocyst quality in pigs.

Role of lipid rafts in neuronal differentiation of dental pulp-derived stem cells

Human dental pulp-derived stem cells (hDPSCs) are characterized by a typical fibroblast-like morphology. They express specific markers for mesenchymal stem cells and are capable of differentiation into osteoblasts, adipoblasts and neurons in vitro. Previous studies showed that gangliosides are involved in the induction of early neuronal differentiation of hDPSCs. This study was undertaken to investigate the role of lipid rafts in this process. Lipid rafts are signaling microdomains enriched in glycosphingolipids, cholesterol, tyrosine kinase receptors, mono- or heterotrimeric G proteins and GPI-anchored proteins. We preliminary showed that established cells expressed multipotent mesenchymal stromal-specific surface antigens. Then, we analyzed the distribution of lipid rafts, revealing plasma membrane microdomains with GM2 and EGF-R enrichment. Following stimulation with EGF/bFGF, neuronal differentiation was observed. To analyze the functional role of lipid rafts in EGF/bFGF-induced hDPSCs differentiation, cells were preincubated with lipid raft affecting agents, i.e. [D]-PDMP or methyl-β-cyclodextrin. These compounds significantly prevented neuronal-specific antigen expression, as well as Akt and ERK 1/2 phosphorylation, induced by EGF/bFGF, indicating that lipid raft integrity is essential for EGF/bFGF-induced hDPSCs differentiation. These results suggest that lipid rafts may represent specific chambers, where multimolecular signaling complexes, including lipids (gangliosides, cholesterol) and proteins (EGF-R), play a role in hDPSCs differentiation.

Effect of ganglioside GT1b on the in vitro maturation of porcine oocytes and embryonic development

Ganglioside is an acidic glycosphingolipid with sialic acids residues. This study was performed to investigate the effect and mechanism of ganglioside GT1b in porcine oocytes in the process of in vitro maturation (IVM) and preimplantation development. Metaphase II (MII) rates were significantly (P < 0.05) different between the control group and the 5 nM GT1b treatment group. Intracellular glutathione (GSH) levels in oocytes matured with 5 nM and 20 nM and GT1b decreased significantly (P < 0.05). The 10 nM group showed a significant (P < 0.05) decrease in intracellular reactive oxygen species (ROS) levels compared with the control group. Subsequently, the level of intracellular Ca(2+) in oocytes treated with different concentrations of GT1b was measured. Intracellular Ca(2+) was significantly (P < 0.05) increased with a higher concentration of GT1b in a dose-dependent manner. Real-time PCR was performed and showed that the expression of bradykinin 2 receptor (B2R) and calcium/calmodulin-dependent protein kinase II delta (CaMKIIδ) in cumulus cells was significantly (P < 0.05) decreased in the 20 nM GT1b treatment group. Treatment with 5 nM GT1b significantly (P < 0.05) decreased the expression of CaMKIIδ. In oocytes, treatment with 5 nM GT1b significantly (P < 0.05) decreased CaMKIIγ and POU5F1 (POU domain, class 5, transcription factor 1). However, treatment with 20 nM GT1b significantly (P < 0.05) increased the expression of POU5F1. Finally, embryonic developmental data showed no significant differences in the two experiments (parthenogenesis and in vitro fertilization). In conclusion, the results of the present study indicated that GT1b plays an important role in increasing the nuclear maturation rate and decreasing the intracellular ROS levels during IVM. However, GT1b inhibited maturation of the cytoplasm by maintaining intracellular Ca(2+) in the process of oocyte maturation regardless of the cell cycle stage. Therefore, GT1b is thought to act on another mechanism that controls intracellular Ca(2+).

Expression of ganglioside 9-O acetyl GD3 in undifferentiated embryonic stem cells

Embryonic stem cells (ES cells) express a transient and heterogeneous pattern of molecules, which suggests a notable mechanism to control self-renewal avoid the differentiation into germ layers. We show that 9-O-acetyl GD3 (9OacGD3), a highly expressed b-series ganglioside in neural stem (NS) cells, is expressed in undifferentiated mouse ES cells in a heterogeneous fashion. After sorting, undifferentiated 9OacGD3(+) ES cell population had higher levels of nestin and Sox2 mRNA than the 9OacGD3(-) cells. Even with elevated expression of these neural transcription factors, 9OacGD3(+) cells did not give rise to more neural progenitors than 9OacGD3(-) cells. Expression of 9OacGD3 was recovered from 9OacGD3(-) cell population, demonstrating that expression of this ganglioside in mouse embryonic stem cells is transient, and does not reflect cell fate. Our findings show that the ganglioside 9OacGD3 is expressed heterogeneously and transiently in ES cells, and this expression corresponds to higher levels of Sox2 and Nestin transcripts.

Role of gangliosides in the differentiation of human mesenchymal-derived stem cells into osteoblasts and neuronal cells

Gangliosides are complex glycosphingolipids that are the major component of cytoplasmic cell membranes, and play a role in the control of biological processes. Human mesenchymal stem cells (hMSCs) have received considerable attention as alternative sources of adult stem cells because of their potential to differentiate into multiple cell lineages. In this study, we focus on various functional roles of gangliosides in the differentiation of hMSCs into osteoblasts or neuronal cells. A relationship between gangliosides and epidermal growth factor receptor (EGFR) activation during osteoblastic differentiation of hMSCs was observed, and the gangliosides may play a major role in the regulation of the differentiation. The roles of gangliosides in osteoblast differentiation are dependent on the origin of hMSCs. The reduction of ganglioside biosynthesis inhibited the neuronal differentiation of hMSCs during an early stage of the differentiation process, and the ganglioside expression can be used as a marker for the identification of neuronal differentiation from hMSCs. [BMB Reports 2013; 46(11): 527-532]

Plant-derived mAbs have effective anti-cancer activities by increasing ganglioside expression in colon cancers

An epithelial cell adhesion molecule (EpCAM) was selectively expressed in human colorectal carcinoma. Treatment with plant-derived anti-EpCAM mAb (mAbP CO17-1A) and RAW264.7 cells inhibited cell growth in the human colorectal cancer cell line SW620. In SW620 treated with mAbP CO17-1A and RAW264.7 cells, expression of p53 and p21 increased, whereas the expression of G1 phase-related proteins, cyclin D1, CDK4, cyclin E, and CDK2, decreased, similar to mammalian-derived mAb (mAbM) CO17-1A. Similar to mAbM CO17-1A, treatment with mAbP CO17-1A and RAW264.7 cell decreased the expression of anti-apoptotic protein, Bcl-2, but the expression of pro-apoptotic proteins Bax, TNF-α, caspase-3, caspase-6, caspase-8 and caspase-9, increased. Cells treated with mAbP CO17-1A and RAW264.7 cells expressed metastasis-related gangliosides, GM1 and GD1a, similar to mAbM CO17-1A. These results suggest that mAbP CO17-1A is as effective on anti-cancer activity as mAbM CO17-1A.

Isolation and characterization of 2 new human rotator cuff and long head of biceps tendon cells possessing stem cell-like self-renewal and multipotential differentiation capacity

BACKGROUND

Stem cell therapy is expected to offer new alternatives to the traditional therapies of rotator cuff tendon tears. In particular, resident, tissue-specific, adult stem cells seem to have a higher regenerative potential for the tissue where they reside.

HYPOTHESIS

Rotator cuff tendon and long head of the biceps tendon possess a resident stem cell population that, when properly stimulated, may be induced to proliferate, thus being potentially usable for tendon regeneration.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human tendon samples from the supraspinatus and the long head of the biceps were collected during rotator cuff tendon surgeries from 26 patients, washed with phosphate-buffered saline, cut into small pieces, and digested with collagenase type I and dispase. After centrifugation, cell pellets were resuspended in appropriate culture medium and plated. Adherent cells were cultured, phenotypically characterized, and then compared with human bone marrow stromal cells (BMSCs), as an example of adult stem cells, and human dermal fibroblasts, as normal proliferating cells with no stem cell properties.

RESULTS

Two new adult stem cell populations from the supraspinatus and long head of the biceps tendons were isolated, characterized, and cultured in vitro. Cells showed adult stem cell characteristics (ie, they were self-renewing in vitro, clonogenic, and multipotent), as they could be induced to differentiate into different cell types--namely, osteoblasts, adipocytes, and skeletal muscle cells.

CONCLUSION

This work demonstrated that human rotator cuff tendon stem cells and human long head of the biceps tendon stem cells can be isolated and possess a high regenerative potential, which is comparable with that of BMSCs. Moreover, comparative analysis of the sphingolipid pattern of isolated cells with that of BMSCs and fibroblasts revealed the possibility of using this class of lipids as new possible markers of the cell differentiation status.

CLINICAL RELEVANCE

Rotator cuff and long head of the biceps tendons contain a stem cell population that can proliferate in vitro and could constitute an easily accessible stem cell source to develop novel therapies for tendon regeneration.

Impaired neural differentiation of induced pluripotent stem cells generated from a mouse model of Sandhoff disease

Sandhoff disease (SD) is a glycosphingolipid storage disease that arises from mutations in the Hexb gene and the resultant deficiency in β-hexosaminidase activity. This deficiency results in aberrant lysosomal accumulation of the ganglioside GM2 and related glycolipids, and progressive deterioration of the central nervous system. Dysfunctional glycolipid storage causes severe neurodegeneration through a poorly understood pathogenic mechanism. Induced pluripotent stem cell (iPSC) technology offers new opportunities for both elucidation of the pathogenesis of diseases and the development of stem cell-based therapies. Here, we report the generation of disease-specific iPSCs from a mouse model of SD. These mouse model-derived iPSCs (SD-iPSCs) exhibited pluripotent stem cell properties and significant accumulation of GM2 ganglioside. In lineage-directed differentiation studies using the stromal cell-derived inducing activity method, SD-iPSCs showed an impaired ability to differentiate into early stage neural precursors. Moreover, fewer neurons differentiated from neural precursors in SD-iPSCs than in the case of the wild type. Recovery of the Hexb gene in SD-iPSCs improved this impairment of neuronal differentiation. These results provide new insights as to understanding the complex pathogenic mechanisms of SD.

Ganglioside biochemistry

Gangliosides are sialic acid-containing glycosphingolipids. They occur especially on the cellular surfaces of neuronal cells, where they form a complex pattern, but are also found in many other cell types. The paper provides a general overview on their structures, occurrence, and metabolism. Key functional, biochemical, and pathobiochemical aspects are summarized.

Regulation of glycan structures in murine embryonic stem cells: combined transcript profiling of glycan-related genes and glycan structural analysis

The abundance and structural diversity of glycans on glycoproteins and glycolipids are highly regulated and play important roles during vertebrate development. Because of the challenges associated with studying glycan regulation in vertebrate embryos, we have chosen to study mouse embryonic stem (ES) cells as they differentiate into embryoid bodies (EBs) or into extraembryonic endodermal (ExE) cells as a model for cellular differentiation. We profiled N- and O-glycan structures isolated from these cell populations and examined transcripts encoding the corresponding enzymatic machinery for glycan biosynthesis in an effort to probe the mechanisms that drive the regulation of glycan diversity. During differentiation from mouse ES cells to either EBs or ExE cells, general trends were detected. The predominance of high mannose N-glycans in ES cells shifted to an equal abundance of complex and high mannose structures, increased sialylation, and increased α-Gal termination in the differentiated cell populations. Whereas core 1 O-glycan structures predominated in all three cell populations, increased sialylation and increased core diversity characterized the O-glycans of both differentiated cell types. Increased polysialylation was also found in both differentiated cell types. Differences between the two differentiated cell types included greater sialylation of N-glycans in EBs, whereas α-Gal-capped structures were more prevalent in ExE cells. Changes in glycan structures generally, but not uniformly, correlated with alterations in transcript abundance for the corresponding biosynthetic enzymes, suggesting that transcriptional regulation contributes significantly to the regulation of glycan expression. Knowledge of glycan structural diversity and transcript regulation should provide greater understanding of the roles of protein glycosylation in vertebrate development.

Relationship between ganglioside expression and anti-cancer effects of the monoclonal antibody against epithelial cell adhesion molecule in colon cancer

The human colorectal carcinoma-associated GA733 antigen epithelial cell adhesion molecule (EpCAM) was initially described as a cell surface protein selectively expressed in some myeloid cancers. Gangliosides are sialic acid-containing glycosphingolipids involved in inflammation and oncogenesis. We have demonstrated that treatment with anti-EpCAM mAb and RAW264.7 cells significant inhibited the cell growth in SW620 cancer cells, but neither anti-EpCAM mAb nor RAW264.7 cells alone induced cytotoxicity. The relationship between ganglioside expression and the anti- cancer effects of anti-EpCAM mAb and RAW264.7 was investigated by high-performance thin-layer chromatography. The results demonstrated that expression of GM1 and GD1a significantly increased in the ability of anti-EpCAM to inhibit cell growth in SW620 cells. Anti-EpCAM mAb treatment increased the expression of anti-apoptotic proteins such as Bcl-2, but the expression of pro-apoptotic proteins Bax, TNF-α, caspase-3, cleaved caspase-3, and cleaved caspase-8 were unaltered. We observed that anti-EpCAM mAb significantly inhibited the growth of colon tumors, as determined by a decrease in tumor volume and weight. The expression of anti-apoptotic protein was inhibited by treatment with anti-EpCAM mAb, whereas the expression of pro-apoptotic proteins was increased. These results suggest that GD1a and GM1 were closely related to anticancer effects of anti-EpCAM mAb. In light of these results, further clinical investigation should be conducted on anti-EpCAM mAb to determine its possible chemopreventive and/or therapeutic efficacy against human colon cancer.

Scientific literature on monosialoganglioside in the Science Citation Index-Expanded: A bibliometric analysis of articles from 1942 to 2011 by each decade

BACKGROUND

The monosialoganglioside (GM1) is a popular topic of research but the bibliometric analysis of GM1 over the decades in Science Citation Index-Expanded (SCI-E) remains poorly understood.

OBJECTIVE

To identify the global research and to improve the understanding of research trends in the GM1 field from 1942 to 2011.

DESIGN

A bibliometric study.

DATA RETRIEVAL

We performed a bibliometric analysis based on the SCI-E published by the Institute of Scientific Information.

INCLUSIVE CRITERIA

Articles closely related to GM1 were included. Exclusive criteria: (1) Articles related to gangliosidosis, disialo-ganglioside, trisialo-ganglioside or ganglioside GQIb. (2) Document types such as meeting abstracts, reviews, proceedings papers, notes, and letters.

MAIN OUTCOME MEASURES

(1) Type of publication output; (2) number of author outputs; (3) distribution of output in subject categories; (4) publication distribution of countries; (5) distribution of output in journals, and (6) distribution of citations in each decade.

RESULTS

During 1942 to 2011, there were 10 126 papers on GM1 that were added to the SCI. Articles (8 004) were the most frequently used document type comprising 79.0%, followed by meeting abstracts, reviews and proceedings papers. Research on GM1 could be found in the SCI from 1942, it was developed in the 1970s, greatly increased in the 1980s, and reached a peak in the 1990s, and it was slightly decreased in 2000. The distribution of subject categories showed that GM1 research covered both clinical and basic science research. The USA, Japan, and Germany were the three most productive countries, and the publication numbers in the USA were highest in all decades. The Journal of Biological Chemistry, Journal of Neurochemistry and Biochemistry were core subject journals in GM1 studies in each decade.

CONCLUSION

This study highlights the topics in GM1 research that are being published around the world.

Regulatory roles of ganglioside GQ1b in neuronal cell differentiation of mouse embryonic stem cells

Gangliosides play an important role in neuronal differentiation processes. The regulation of ganglioside levels is related to the induction of neuronal cell differentiation. In this study, the ST8Sia5 gene was transfected into mESCs and then differentiated into neuronal cells. Interestingly, ST8Sia5 gene transfected mESCs expressed GQ1b by HPTLC and immunofluorescence analysis. To investigate the effects of GQ1b over-expression in neurogenesis, neuronal cells were differentiated from GQ1b expressing mESCs in the presence of retinoic acid. In GQ1b expressing mESCs, increased EBs formation was observed. After 4 days, EBs were co-localized with GQ1b and nestin, and GFAP. Moreover, GQ1b co-localized with MAP-2 expressing cells in GQ1b expressing mESCs in 7-day-old EBs. Furthermore, GQ1b expressing mESCs increased the ERK1/2 MAP kinase pathway. These results suggest that the ST8Sia5 gene increases ganglioside GQ1b and improves neuronal differentiation via the ERK1/2 MAP kinase pathway.