Ribosomal protein uS7/Rps5 serine-223 in protein kinase-mediated phosphorylation and ribosomal small subunit maturation.

Cellular translation should be precisely controlled in response to extracellular cues. However, knowledge is limited concerning signal transduction-regulated translation. In the present study, phosphorylation was identified in the 40S small subunit ribosomal protein uS7 (Yjr123w/previously called as Rps5) by Ypk1 and Pkc1, AGC family protein kinases in yeast Saccharomyces cerevisiae.

Psychosine-triggered endomitosis is modulated by membrane sphingolipids through regulation of phosphoinositide 4,5-bisphosphate production at the cleavage furrow.

Endomitosis is a special type of mitosis in which only cytokinesis-the final step of the cell division cycle-is defective, resulting in polyploid cells. Although endomitosis is biologically important, its regulatory aspects remain elusive. Psychosine, a lysogalactosylceramide, prevents proper cytokinesis when supplemented to proliferating cells.

Fpk1/2 kinases regulate cellular sphingoid long-chain base abundance and alter cellular resistance to LCB elevation or depletion.

Sphingolipids are a family of eukaryotic lipids biosynthesized from sphingoid long-chain bases (LCBs). Sphingolipids are an essential class of lipids, as their depletion results in cell death. However, acute LCB supplementation is also toxic; thus, proper cellular LCB levels should be maintained.

In vivo role of aldehyde reductase.

Background: Aldehyde reductase (AKR1A; EC 1.1.1.

Orm protein phosphoregulation mediates transient sphingolipid biosynthesis response to heat stress via the Pkh-Ypk and Cdc55-PP2A pathways.

Sphingoid intermediates accumulate in response to a variety of stresses, including heat, and trigger cellular responses. However, the mechanism by which stress affects sphingolipid biosynthesis has yet to be identified. Recent studies in yeast suggest that sphingolipid biosynthesis is regulated through phosphorylation of the Orm proteins, which in humans are potential risk factors for childhood asthma.

CD22 serves as a receptor for soluble IgM.

CD22 (Siglec-2) is a B-cell membrane-bound lectin that recognizes glycan ligands containing α2,6-linked sialic acid (α2,6Sia) and negatively regulates signaling through the B-cell Ag receptor (BCR). Although CD22 has been investigated extensively, its precise function remains unclear due to acting multiple phases. Here, we demonstrate that CD22 is efficiently activated in trans by complexes of Ag and soluble IgM (sIgM) due to the presence of glycan ligands on sIgM.

Quantitative transcriptomic profiling of branching in a glycosphingolipid biosynthetic pathway.

Cellular biosynthesis of macromolecules often involves highly branched enzyme pathways, thus cellular regulation of such pathways could be rather difficult. To understand the regulatory mechanism, a systematic approach could be useful. We genetically analyzed a branched biosynthetic pathway for glycosphingolipid (GSL) GM1 using correlation index-based responsible enzyme gene screening (CIRES), a novel quantitative phenotype-genotype correlation analysis.

Induction of feline immunodeficiency virus from a chronically infected feline T-lymphocyte cell line.

The infection of the feline T-lymphocyte cell line FeT-J with the feline immunodeficiency virus (FIV) Petaluma strain led to the establishment of nonvirus-producing cells. One clone (C15) obtained by limiting dilution was found to express FIV in response to chemical inducers of retroviruses. The chemical treatment of C15 cells led to not only FIV protein synthesis but also an augmentation of viral production.

CD22-antagonists with nanomolar potency: the synergistic effect of hydrophobic groups at C-2 and C-9 of sialic acid scaffold.

In earlier studies, we identified the C-9 amido derivative 1 (9-(4'-hydroxy-4-biphenyl)acetamido-9-deoxy-Neu5Gcα2-6GalOMP) and the C-9 amino derivative 2 (9-(4'-hydroxy-4-biphenyl)methylamino-9-deoxy-Neu5Gcα2-6GalOMP) have the most promising affinity for mouse CD22 and human CD22, respectively. Replacing the subterminal galactose residue (2-6Gal-OMP) of 1 with benzyl (5) or biphenylmethyl (6) as aglycone led to even higher potency for mCD22. In this study, both compounds showed improved potency and selectivity for CD22 (IC(50) 70 nM) and 712-fold more selective for CD22 than for MAG.

Sphingosylphosphorylcholine and lysosulfatide have inverse regulatory functions in monocytic cell differentiation into macrophages.

Sphingolipids act as signaling mediators that regulate a diverse range of cellular events. Although numerous sphingolipid functions have been studied, little is known about the effect of sphingolipids on monocyte differentiation into macrophages. Here, we report that two lysosphingolipids, sphingosylphosphorylcholine (SPC) and lysosulfatide (LSF), inversely affect macrophagic differentiation of monocytic cell lines, U937 and THP-1.

Identification of Ypk1 as a novel selective substrate for nitrogen starvation-triggered proteolysis requiring autophagy system and endosomal sorting complex required for transport (ESCRT) machinery components.

Nitrogen starvation-mediated reduction of Ypk1 is suggested to suppress translational initiation, possibly in parallel with the target of rapamycin complex 1 (TORC1) signaling. However, the molecular mechanism that regulates Ypk1 in nitrogen-starved cells is poorly understood. Here we report that Ypk1 is a novel selective substrate for nitrogen starvation-triggered proteolysis requiring autophagy system.

Synthesis and binding analysis of unique AG2 pentasaccharide to human Siglec-2 using NMR techniques.

Siglec-2 is a mammalian sialic acid binding protein expressed on B-cell surfaces and is involved in the modulation of B-cell mediated immune response. We synthesized a unique starfish ganglioside, AG2 pentasaccharide Galfbeta(1-3)Galpalpha(1-4)Neu5Acalpha(2-3)Galpbeta(1-4)Glcp, and found that the synthetic pentasaccharide binds to human Siglec-2 by performing (1)H NMR experiments. Saturation transfer difference NMR experiments indicated that the C7-C9 side-chain and the acetamide moiety of the central sialic acid residue were located in the binding face of human Siglec-2.

Anomalous expression of Thy1 (CD90) in B-cell lymphoma cells and proliferation inhibition by anti-Thy1 antibody treatment.

The anti-CD20 monoclonal antibody (Ab) rituximab is accepted to be an effective therapeutic Ab for malignant B-cell lymphoma; however, discovery of other cell surface antigens is required for the option of antibody medicine. Considering that many tumor-associated antigens are glycans, we have searched glycoconjugates for the candidate antigens that therapeutic Abs target. To this end, we first focused on the difference in the glycogenes expression in terms of Epstein-Barr virus (EBV) infection of a Burkitt's lymphoma cell line, Akata.

Immunological property of antibodies against N-glycolylneuraminic acid epitopes in cytidine monophospho-N-acetylneuraminic acid hydroxylase-deficient mice.

The generation of pigs devoid of Galalpha1,3Galbeta1,4GlcNAc (Gal) residues has stimulated interest in non-Gal Ags as potentially important targets for Ab binding leading to rejection of pig organ xenografts in humans. Although N-glycolylneuraminic acid (NeuGc) epitopes, which are widely expressed on the endothelial cells of all mammals except humans, are likely targets of anti-non-Gal Abs, this aspect has not been investigated intensively owing to the absence of an appropriate animal model. In this study, we used CMAH(-/-) mice, which are completely deficient in NeuGc and thus produce anti-NeuGc Abs.

Differential CXCR4 expression and function in subpopulations of the feline lymphoma cell line 3201 susceptible to feline immunodeficiency virus.

The infection of feline thymic lymphoma 3201 cells with a cell culture-adapted Petaluma strain of feline immunodeficiency virus (FIV) led to the establishment of survivor cells designated as 3201-S after a productive infection associated with extensive cell killing. 3201-S cells were free of FIV DNA, and were found to express CXCR4, a coreceptor for infection but not CD134, a primary receptor. When 3201-S cells were reinfected with FIV, viral DNA was transiently detectable for 5 days postinfection, indicating that 3201-S cells cannot support the FIV replicative cycle.

Protective effect of N-glycan bisecting GlcNAc residues on beta-amyloid production in Alzheimer's disease.

Alteration of glycoprotein glycans often changes various properties of the target glycoprotein and contributes to a wide variety of diseases. Here, we focused on the N-glycans of amyloid precursor protein whose cleaved fragment, beta-amyloid, is thought to cause much of the pathology of Alzheimer's disease (AD). We previously determined the N-glycan structures of normal and mutant amyloid precursor proteins (the Swedish type and the London type).

Potent small molecule mouse CD22-inhibitors: exploring the interaction of the residue at C-2 of sialic acid scaffold.

Our previous study revealed that compound 1 (9-(4'-hydroxy-4-biphenyl)acetamido-9-deoxy-Neu5Gcalpha2-6GalOMP) has the most promising affinity for mCD22. Replacing the subterminal galactose residue of 1 with benzyl or biphenylmethyl as aglycone led to 38- and 20-fold higher potency, respectively. This discovery represents a new direction in inhibitor design suitable for pharmaceutical development.

Tropoelastin regulates chemokine expression in fibroblasts in Costello syndrome.

Costello syndrome is a multiple congenital anomaly associated with growth and mental retardation, cardiac and skeletal anomalies, and a predisposition to develop neoplasia. Comprehensive expression analysis revealed remarkable up-regulation of several cytokines and chemokines including Gro family proteins, interleukin-1beta (IL-1beta), IL-8 and MCP-1 but down-regulation of extracellular matrix components including collagens and proteoglycans of skin fibroblasts derived from a Japanese Costello syndrome patient characterized by significantly reduced tropoelastin mRNA, impaired elastogenesis and enhanced cell proliferation. In contrast, decreases in these chemokines and IL-1beta expression were observed in Costello fibroblastic cell lines stably expressing the bovine tropoelastin (btEln) gene and in restored elastic fibers.

Establishment of the culture model system that reflects the process of terminal differentiation of connective tissue-type mast cells.

To understand physiological roles of tissue mast cells, we established a culture system where bone marrow-derived immature mast cells differentiate into the connective tissue-type mast cell (CTMC)-like cells through modifying the previous co-culture system with Swiss 3T3 fibroblasts. Our system was found to reproducibly mimic the differentiation of CTMCs on the basis of several criteria, such as granule maturation and sensitivity to cationic secretagogues. The gene expression profile obtained by the microarray analyses was found to reflect many aspects of the differentiation.

Wheat germ agglutinin stains dispersed post-golgi vesicles after treatment with the cytokinesis inhibitor psychosine.

The galactosylsphingosine psychosine (Psy) is one of the sphingolipids and induce the formation of multinuclear cells in several cell lines by inhibiting cytokinesis. In the present report, we show that intracellular organelles, including wheat germ agglutinin (WGA)-positive vesicles and early endosomes, are selectively dispersed by Psy. WGA is a conventional Golgi marker and WGA-positive vesicles appeared to co-localize with the Golgi apparatus in untreated cells.

Correlation index-based responsible-enzyme gene screening (CIRES), a novel DNA microarray-based method for enzyme gene involved in glycan biosynthesis.

Background: Glycan biosynthesis occurs though a multi-step process that requires a variety of enzymes ranging from glycosyltransferases to those involved in cytosolic sugar metabolism. In many cases, glycan biosynthesis follows a glycan-specific, linear pathway. As glycosyltransferases are generally regulated at the level of transcription, assessing the overall transcriptional profile for glycan biosynthesis genes seems warranted.

Human B-lymphocytes express alpha2-6-sialylated 6-sulfo-N-acetyllactosamine serving as a preferred ligand for CD22/Siglec-2.

CD22/Siglec-2, an important inhibitory co-receptor on B-lymphocytes, is known to recognize alpha2-6-sialylated glycan as a specific ligand. Here we propose that the alpha2-6-sialylated and 6-GlcNAc-sulfated determinant serves as a preferred ligand for CD22 because the binding of a human B-cell line to CD22 was almost completely abrogated after incubating the cells with NaClO3, an inhibitor of cellular sulfate metabolism, and was also significantly inhibited by a newly generated monoclonal antibody specific to the alpha2-6-sialylated 6-sulfo-N-acetyllactosamine (LacNAc) determinant (KN343, murine IgM). The alpha2-6-sialylated 6-sulfo-LacNAc determinant defined by the antibody was significantly expressed on a majority of normal human peripheral B-lymphocytes as well as follicular B-lymphocytes in peripheral lymph nodes.