The Inhibitory Role of α2,6-Sialylation in Adipogenesis.

Adipose tissue plays critical roles in obesity and related diseases such as diabetes and cardiovascular diseases. Previous reports suggest that glycans, the most common posttranslational modifications, are involved in obesity-related diseases, but what type of glycan regulates adipogenesis during obesity remains unclear. In this study, we first quantified the mRNA levels of 167 genes (encoding 144 glycosyltransferases and 23 related enzymes) in visceral adipose tissues (VATs) from control mice and high-fat diet (HFD)-induced obese mice.

A keratan sulfate disaccharide prevents inflammation and the progression of emphysema in murine models.

Emphysema is a typical component of chronic obstructive pulmonary disease (COPD), a progressive and inflammatory airway disease. However, no effective treatment currently exists. Here, we show that keratan sulfate (KS), one of the major glycosaminoglycans produced in the small airway, decreased in lungs of cigarette smoke-exposed mice.

Aglycon diversity of brain sterylglucosides: structure determination of cholesteryl- and sitosterylglucoside.

To date, sterylglucosides have been reported to be present in various fungi, plants, and animals. In bacteria, such as Helicobacter pylori, proton NMR spectral analysis of isolated 1-O-cholesteryl-β-d-glucopyranoside (GlcChol) demonstrated the presence of an α-glucosidic linkage. By contrast, in animals, no detailed structural analysis of GlcChol has been reported, in part because animal-derived samples contain a high abundance of glucosylceramides (GlcCers)/galactosylceramides, which exhibit highly similar chromatographic behavior to GlcChol.

A Reduction-Based Sensor for Acrolein Conjugates with the Inexpensive Nitrobenzene as an Alternative to Monoclonal Antibody.

Acrolein, a highly toxic α, β-unsaturated aldehyde, has been a longstanding key biomarker associated with a range of disorders related to oxidative stresses. One of the most promising methods for detecting acrolein involves the use of antibodies that can recognize the acrolein-lysine conjugate, 3-formyl-3, 4-dehydropiperidines (FDP), within oxidatively stressed cells and tissues from various disease states. We have uncovered here that FDP could reduce nitroarenes in high yields at 100 °C in the presence of excess CaCl as a Lewis acid promoter.

Hyaluronan Production Regulates Metabolic and Cancer Stem-like Properties of Breast Cancer Cells via Hexosamine Biosynthetic Pathway-coupled HIF-1 Signaling.

Cancer stem cells (CSCs) represent a small subpopulation of self-renewing oncogenic cells. As in many other stem cells, metabolic reprogramming has been implicated to be a key characteristic of CSCs. However, little is known about how the metabolic features of cancer cells are controlled to orchestrate their CSC-like properties.

The Muscular Dystrophy Gene TMEM5 Encodes a Ribitol β1,4-Xylosyltransferase Required for the Functional Glycosylation of Dystroglycan.

A defect in O-mannosyl glycan is the cause of α-dystroglycanopathy, a group of congenital muscular dystrophies caused by aberrant α-dystroglycan (α-DG) glycosylation. Recently, the entire structure of O-mannosyl glycan, [3GlcAβ1-3Xylα1]-3GlcAβ1-4Xyl-Rbo5P-1Rbo5P-3GalNAcβ1-3GlcNAcβ1-4 (phospho-6)Manα1-, which is required for the binding of α-DG to extracellular matrix ligands, has been proposed. However, the linkage of the first Xyl residue to ribitol 5-phosphate (Rbo5P) is not clear.

N-glycans of growth factor receptors: their role in receptor function and disease implications.

Numerous signal-transduction-related molecules are secreted proteins or membrane proteins, and the mechanism by which these molecules are regulated by glycan chains is a very important issue for developing an understanding of the cellular events that transpire. This review covers the functional regulation of epidermal growth factor receptor (EGFR), ErbB3 and the transforming growth factor β (TGF-β) receptor by N-glycans. This review shows that the N-glycans play important roles in regulating protein conformation and interactions with carbohydrate recognition molecules.

3D Structure and Interaction of p24β and p24δ Golgi Dynamics Domains: Implication for p24 Complex Formation and Cargo Transport.

The p24 family consists of four subfamilies (p24α, p24β, p24γ, and p24δ), and the proteins are thought to form hetero-oligomeric complexes for efficient transport of cargo proteins from the endoplasmic reticulum to the Golgi apparatus. The proteins possess a conserved luminal Golgi dynamics (GOLD) domain, whose functions are largely unknown. Here, we present structural and biochemical studies of p24β1 and p24δ1 GOLD domains.

6-Azido-6-deoxy-l-idose as a Hetero-Bifunctional Spacer for the Synthesis of Azido-Containing Chemical Probes.

The design of 6-azido-6-deoxy-l-idose for use as a hetero-bifunctional spacer is reported. The hemiacetal at one terminus is an equivalent of an aldehyde and can react with nucleophiles, such as amino groups and electron-rich aromatics. The azido group at the other terminus bio-orthogonally undergoes a Hüisgen [3+2] cycloaddition with an acetylene.

High-Sensitivity and Low-Toxicity Fucose Probe for Glycan Imaging and Biomarker Discovery.

Fucose, a terminal sugar in glycoconjugates, critically regulates various physiological and pathological phenomena, including cancer development and inflammation. However, there are currently no probes for efficient labeling and detection of this sugar. We chemically synthesized a novel series of alkynyl-fucose analogs as probe candidates and found that 7-alkynyl-fucose gave the highest labeling efficiency and low cytotoxicity.

Glycation vs. glycosylation: a tale of two different chemistries and biology in Alzheimer's disease.

In our previous studies, we reported that the activity of an anti-oxidant enzyme, Cu,Zn-superoxide dismutase (Cu,Zn-SOD) became decreased as the result of glycation in vitro and in vivo. Glycated Cu,Zn-SOD produces hydroxyl radicals in the presence of transition metals due to the formation of a Schiff base adduct and a subsequent Amadori product. This results in the site-specific cleavage of the molecule, followed by random fragmentation.

Epigenetic regulation of neural N-glycomics.

Glycan expression is tightly regulated in a cell-type-specific manner, which is essential for the diverse functions of glycans. In particular, neural cells such as neurons and astrocytes are known to express unique functional glycans not found in other cells, and these glycans play critical roles in high-order brain functions and various neurological disorders. However, little is known about how the expression of these neural glycans is established and maintained.

Catabolism of N-glycoproteins in mammalian cells: Molecular mechanisms and genetic disorders related to the processes.

N-glycans on glycoproteins serve as one of the most important co- and post-translational modifications of proteins, and it has been well established that they play pivotal roles in controlling the physicochemical and/or physiological properties of the carrier proteins. The biosynthetic/processing pathways for N-glycans have been well characterized in mammalian cells. There are, however, issues that remain to be clarified concerning aspects of their degradation.

Disease-associated glycans on cell surface proteins.

Most of membrane molecules including cell surface receptors and secreted proteins including ligands are glycoproteins and glycolipids. Therefore, identifying the functional significance of glycans is crucial for developing an understanding of cell signaling and subsequent physiological and pathological cellular events. In particular, the function of N-glycans associated with cell surface receptors has been extensively studied since they are directly involved in controlling cellular functions.

The α-Glycosidation of Partially Unprotected N-Acetyl and N-Glycolyl Sialyl Donors in the Absence of a Nitrile Solvent Effect.

The synthesis of α-sialosides is one of the most difficult reactions in carbohydrate chemistry and is considered to be both a thermodynamically and kinetically disfavored process. The use of acetonitrile as a solvent is an effective solution for the α-selective glycosidation of N-acetyl sialic acids. In this report, we report on the α-glycosidation of partially unprotected N-acetyl and N-glycolyl donors in the absence of a nitrile solvent effect.

Epiblastin A Induces Reprogramming of Epiblast Stem Cells Into Embryonic Stem Cells by Inhibition of Casein Kinase 1.

The discovery of novel small molecules that induce stem cell reprogramming and give efficient access to pluripotent stem cells is of major importance for potential therapeutic applications and may reveal novel insights into the factors controlling pluripotency. Chemical reprogramming of mouse epiblast stem cells (EpiSCs) into cells corresponding to embryonic stem cells (cESCs) is an inefficient process. In order to identify small molecules that promote this cellular transition, we analyzed the LOPAC library in a phenotypic screen monitoring Oct4-GFP expression and identified triamterene (TR) as initial hit.

Small molecules that target phosphorylation dependent protein-protein interaction.

Protein-protein interaction is one of the key events in the signal transduction pathway. The interaction changes the conformations, activities, localization and stabilities of the proteins, and transduces the signal to the next step. Frequently, this interaction occurs upon the protein phosphorylation.

Crystal structure of human dendritic cell inhibitory receptor C-type lectin domain reveals the binding mode with N-glycan.

Human dendritic cell inhibitory receptor (DCIR) is a C-type lectin receptor expressed in classical dendritic cells and accepts several oligosaccharide ligands including N-glycans. Here, we report the crystal structures of human DCIR C-type lectin domains in the absence and presence of a branched N-glycan unit. The domain has a typical C-type lectin fold and two bound calcium ions.

Structural Analysis of Free N-Glycans in α-Glucosidase Mutants of Saccharomyces cerevisiae: Lack of the Evidence for the Occurrence of Catabolic α-Glucosidase Acting on the N-Glycans.

Saccharomyces cerevisiae produces two different α-glucosidases, Glucosidase 1 (Gls1) and Glucosidase 2 (Gls2), which are responsible for the removal of the glucose molecules from N-glycans (Glc3Man9GlcNAc2) of glycoproteins in the endoplasmic reticulum. Whether any additional α-glucosidases playing a role in catabolizing the glucosylated N-glycans are produced by this yeast, however, remains unknown. We report herein on a search for additional α-glucosidases in S.

Atomic visualization of a flipped-back conformation of bisected glycans bound to specific lectins.

Glycans normally exist as a dynamic equilibrium of several conformations. A fundamental question concerns how such molecules bind lectins despite disadvantageous entropic loss upon binding. Bisected glycan, a glycan possessing bisecting N-acetylglucosamine (GlcNAc), is potentially a good model for investigating conformational dynamics and glycan-lectin interactions, owing to the unique ability of this sugar residue to alter conformer populations and thus modulate the biological activities.

Subgroup differences in 'brain-type' transferrin and α-synuclein in Parkinson's disease and multiple system atrophy.

Two transferrin (Tf) glycan-isoforms were previously found in cerebrospinal fluid (CSF); one appears to be derived from serum (Tf-2) and the other from choroid plexus, a CSF-producing tissue (Tf-1). To analyse metabolic differences associated with the two isoforms, their ratio (Tf-2/Tf-1) was defined as the Tf index. Here we report that Tf indices of patients with tauopathies including Alzheimer's disease (2.

Proteomic and glycomic analyses of a lung-specific protein surfactant protein-D.

In order to verify the protein enriched from pooled human sera to be a lung-specific protein surfactant protein-D (SP-D), we performed peptide mass fingerprinting (PMF)-based protein identification. MASCOT search results of the obtained PMF unequivocally demonstrated that it is identical to human SP-D. Meanwhile, we performed MALDI-QIT-TOF mass spectrometry-based N-glycomic analysis of the recombinant human SP-D produced in murine myeloma cells.

In vivo imaging of advanced glycation end products (AGEs) of albumin: first observations of significantly reduced clearance and liver deposition properties in mice.

Advanced glycation end products (AGEs) are associated with various diseases, especially during aging and the development of diabetes and uremia. To better understand these biological processes, investigation of the in vivo kinetics of AGEs, i.e.

Identification of a Post-translational Modification with Ribitol-Phosphate and Its Defect in Muscular Dystrophy.

Glycosylation is an essential post-translational modification that underlies many biological processes and diseases. α-dystroglycan (α-DG) is a receptor for matrix and synaptic proteins that causes muscular dystrophy and lissencephaly upon its abnormal glycosylation (α-dystroglycanopathies). Here we identify the glycan unit ribitol 5-phosphate (Rbo5P), a phosphoric ester of pentose alcohol, in α-DG.

Visualizing Trimming Dependence of Biodistribution and Kinetics with Homo- and Heterogeneous N-Glycoclusters on Fluorescent Albumin.

A series of N-glycans, each sequentially trimmed from biantennary sialoglycans, were homo- or heterogeneously clustered efficiently on fluorescent albumin using a method that combined strain-promoted alkyne-azide cyclization and 6π-azaelectrocyclization. Noninvasive in vivo kinetics and dissection analysis revealed, for the first time, a glycan-dependent shift from urinary to gall bladder excretion mediated by sequential trimming of non-reducing end sialic acids. N-glycoalbumins that were trimmed further, in particular, GlcNAc- and hybrid biantennary-terminated congeners, were selectively taken up by sinusoidal endothelial and stellate cells in the liver, which are critical for diagnosis and treatment of liver fibrillation.