Sugar microanalysis by HPLC with benzoylation: improvement via introduction of a C-8 cartridge and a high efficiency ODS column

An HPLC protocol for sugar microanalysis based on the formation of ultraviolet-absorbing benzoyl chloride derivatives was improved. Here, samples were prepared with a C-8 cartridge and analyzed with a high efficiency ODS column, in which porous spherical silica particles 3 microm in diameter were packed. These devices allowed us to simultaneously quantify multiple sugars and sugar alcohols up to 10 ng/ml and to provide satisfactory separations of some sugars, such as fructose and myo-inositol and sorbitol and mannitol. This protocol, which does not require special apparatuses, should become a powerful tool in sugar research.     

Roles of the Akt/mTOR/p70S6K and ERK1/2 signaling pathways in curcumin-induced autophagy

Curcumin has a potent anticancer effect and is a promising new therapeutic strategy. We previously demonstrated that curcumin induced non-apoptotic autophagic cell death in malignant glioma cells in vitro and in vivo. This compound inhibited the Akt/mammalian target of rapamycin/p70 ribosomal protein S6 kinase pathway and activated the extracellular signal-regulated kinases 1/2 thereby inducing autophagy. Interestingly, activation of the first pathway inhibited curcumin-induced autophagy and cytotoxicity, whereas inhibition of the latter pathway inhibited curcumin-induced autophagy and induced apoptosis, thus augmenting the cytotoxicity of curcumin. These results imply that these two autophagic pathways have opposite effects on curcumin's cytotoxicity. However, inhibition of nuclear factor kappaB, which is the main target of curcumin for its anticancer effect, was not observed in malignant glioma cells. These results suggest that autophagy but not nuclear factor kappaB plays a central role in curcumin anticancer therapy and warrant further investigation toward application in patients with malignant gliomas. Here, we discuss the therapeutic role of two autophagic pathways influenced by curcumin.     

Relationship between endothelin and thromboxane A2 in rat liver microcirculation.

In our previous study, we determined changes in hepatic blood flow using a Laser Doppler blood flow meter after i.v. injection of endothelin-1 (ET-1) or endothelin-3 (ET-3) at 2 nmol/kg in rats and found that ET-3 caused greater decreases in blood flow than ET-1. In the present study, we determined how the arachidonic acid cascade, mainly thromboxane A2 (TXA2), is related to ET-1 and ET-3 using indomethacin (INDO), which inhibits the biosynthesis of prostaglandin (PG), and OKY-046, a selective inhibitor of TXA2 synthesis. In the first series of experiments, ET-1 and ET-3 were administered after inhibiting the biosynthesis of PG by s.c. injection of 2 mg/kg of INDO. While INDO failed to inhibit the slight decrease in hepatic blood flow induced by ET-1, it significantly inhibited the marked decrease in hepatic blood flow elicited by ET-3. In the next series of experiments, ET-1 and ET-3 were administered after administration of 20 mg/kg of OKY-046. OKY-046 showed no effects in animals treated with ET-1, as in those pre-treated with INDO, while it significantly inhibited the decreases in hepatic blood flow induced by ET-3. These findings suggest that ET-1 decreases hepatic blood flow due to its direct effects although to a lesser extent than ET-3, while ET-3 does so due not only to its direct effects but also to TXA2-mediated effects. It is therefore likely that in addition to ET family peptides, PG-mediated mechanisms are involved in the regulation of hepatic microcirculation by ETs.     

Human ABCA1 contains a large amino-terminal extracellular domain homologous to an epitope of Sjögren's Syndrome

ABCA1 has been suggested to play a key role in cellular lipid release from peripheral cells. In order to study structure-function relationship of this protein, the protein product of a full-length human ABCA1 cDNA was examined for its functions and topological orientation. The electrophoretic mobilities of human ABCA1 expressed in transfected cells increased when treated with N-glycosidase F, suggesting that ABCA1 is highly glycosylated. The ABCA1 was photoaffinity-labeled with ATP and mediated the apoA-I-dependent-release of cholesterol and phospholipid. The influenza hemagglutinin (HA) epitope was introduced into the amino-terminus (N-HA) or between the residues 207 and 208 (207-HA) of the protein. While an antibody against the C-terminus peptide of ABCA1 detected both fusion proteins, an anti-HA antibody did not react with the N-HA fusion protein. Confocal microscopy demonstrated strong cell surface signal with the anti-HA antibody of nonpermeabilized HEK293 cells expressing the 207-HA fusion protein. The results suggested that the signal peptide in the amino-terminal region is cleaved off in its mature form and that the following large hydrophilic region is exposed to outside of cells unlike previously proposed models. We found that this amino-terminal extracellular domain contains a segment homologous to the autoantigen SS-N, an epitope of Sj?gren's syndrome, and further identified that ABCA7 codes for the autoantigen SS-N.     

A "chimeric" C57l-derived Ly49 inhibitory receptor resembling the Ly49D activation receptor.

Ly49D is a natural killer (NK) cell activation receptor that is responsible for differential mouse inbred strain-determined lysis of Chinese hamster ovary (CHO) cells. Whereas C57BL/6 NK cells kill CHO, BALB/c-derived NK cells cannot kill because they lack expression of Ly49D. Furthermore, the expression of Ly49D, as detected by monoclonal antibody 4E4, correlates well with CHO lysis by NK cells from different inbred strains. However, one discordant mouse strain was identified; C57L NK cells express the mAb 4E4 epitope but fail to lyse CHO cells. Herein we describe a Ly49 molecule isolated from C57L mice that is recognized by mAb 4E4 (anti-Ly49D). Interestingly, this molecule shares extensive similarity to Ly49D(B6) in its extracellular domain, but its cytoplasmic and transmembrane domains are identical to the inhibitory receptor Ly49A(B6), including a cytoplasmic ITIM. This molecule bears substantial overall homology to the previously cloned Ly49O molecule from 129 mice the serologic reactivity and function of which were undefined. Cytotoxicity experiments revealed that 4E4(+) LAK cells from C57L mice failed to lyse CHO cells and inhibited NK cell function in redirected inhibition assays. MHC class I tetramer staining revealed that the Ly49O(C57L)-bound H-2D(d) and lysis by 4E4(+) C57L LAK cells is inhibited by target H-2D(d). The structural basis for ligand binding was also examined in the context of the recent crystallization of a Ly49A-H-2D(d) complex. Therefore, this apparently "chimeric" Ly49 molecule serologically resembles an NK cell activation receptor but functions as an inhibitory receptor.     

A method for micrometer resolution patterning of primary culture neurons for SPM analysis

In this work we present a method for ultra-fine patterning of primary culture neuron cell growth, which is compatible for scanning near-field optical atomic force microscopy (SNOAM) analysis. SNOAM uses near-field optics to break the fundamental diffraction limit imposed on normal microscopy. SNOAM can achieve sub-100 nm optical resolutions, but requires transparent, open substrates. The ability to do physiological measurements on patterns of neurons, combined with ultra high resolution optical and fluorescent analysis, is useful in the study of long-term potentiation. The patterning method consists of chemical guidance with an element of physical confinement and allows for ultra-fine patterning of neural growth on transparent glass substrates. Substrates consist of microfabricated perfluoropolymer barrier structures on glass. Poly-L-lysine was selectively deposited using a silicone-based microfluidic stencil aligned to the perfluoropolymer/glass substrate. Primary culture neurons were extracted from 8-day-old chicks and grown for 3 days to form good networks. This patterning system shows very specific growth with patterning separations down to the level of individual neurites. Fluorescent imaging was carried out on both cell viability during growth and immuno-tagged microtubule-associated proteins on the neurites. Neurons inside the patterned structures were imaged and analyzed with a tapping mode SNOAM.     

Very-long-chain fatty acid-containing phospholipids accumulate in fatty acid synthase temperature-sensitive mutant strains of the fission yeast Schizosaccharomyces pombe fas2/lsd1

Fission yeast lsd1 strains show aberrant mitosis with a lsd phenotype, large and small daughter nuclei, and a very thick septum, the phenotypic expression being temperature-sensitive. The lsd1(+) gene is the homologue of the budding yeast FAS2 gene encoding the fatty acid synthase alpha-subunit as reported previously (S. Saitoh, K. Takahashi, K. Nabeshima, Y. Yamashita, Y. Nakaseko, A. Hirata, M. Yanagida, J. Cell Biol. 134 (1996) 949--961). In this paper, lsd1 is considered to represent fas2. Here, three fas2 strains were investigated and found to have missense point mutations at different sites in the gene encoding the alpha-subunit of fatty acid synthase. The mutation affected only slightly the enzymatic activities monitored in vitro. Unexpectedly, abnormal phospholipids, phosphatidylcholine and phosphatidylethanolamine, both of which contain a very-long-chain fatty acyl residue (1-melissoyl-2-oleolyl-sn-glycero-3-phosphocholine and 1-melissoyl-2-oleolyl-sn-glycero-3-phosphoethanolamine), accumulated in fas2 strains in a temperature-sensitive manner. Rescue of the fas2 strains by addition of palmitate to the medium at restrictive temperature was accompanied by disappearance of these abnormal phospholipids. Accumulation of these lipids in membranes may cause alteration of various cellular functions.     

Novel lectin-like proteins on the surface of human monocytic leukemia cell line THP-1 cells that recognize oxidized cells

Presence of lectin-like receptors on the membranes of human monocytic leukemia cell line THP-1 cells for clustered sialylated poly-N-acetyllactosaminyl sugar chains on the membranes of oxidized erythrocytes and T-lympoid cells was investigated. Membranes of THP-1 cells differentiated into macrophages were solubilized, and the membrane proteins obtained by affinity chromatographies using lactoferrin-Sepharose and band 3-Sepharose were purified by successive DE column chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Proteins of 50, 60, and 80 kDa with specificity to bind to sialylated poly-N-acetyllactosaminyl sugar chains were detected in the chromatographic fractions. A 50-kDa protein was isolated in a pure form. N-Terminal amino acid sequence of the protein was Lys-Gln-Lys-Val-Ala-Gly-Lys-Gln-Pro-Val-, which has not been found in the N-terminal regions of the hitherto known proteins. The antibody, raised against the chemially synthesized peptide composed of the N-terminal amino acid sequence, bound to 50-, 60-, and 80-kDa proteins as analyzed by immunoblotting and immunoprecipitation, indicating that these proteins had the same N-terminal amino acid sequence. The results demonstrate that THP-1 cells have novel 50-, 60-, and 80-kDa lectin-like proteins with the same N-terminal amino acid sequence on the cell surface which would bind to clustered sialylated poly-N-acetyllactosaminyl sugar chains generated on oxidized erythrocytes and T-lymphoid cells.