Structural features of nucleosomes in interphase and metaphase chromosomes

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Different forms of 130 kD connective tissue protein are specific for boundaries in the nervous system and basement membrane of muscle cells in leech

The nervous system and muscle tissue of the leech express two different organ-specific forms of connective tissue protein. The nervous system-specific form appears in regional boundaries separating cell bodies, axonal tracts and areas of the neuropile during late embryogenesis. In contrast, the muscle-specific form appears earlier during development in the basement membrane of muscle cells. In extraction experiments both forms behave like extracellular matrix proteins and because of their molecular weight, are considered members of a group of cell type-specific 130 kD proteins (leech gp130s). How ever, the two forms differ in their posttranslational modification. As determined by Con A and lentil lectin affinity chromatography, only the nervous system-specific, but not the muscle-specific form, has fucosylated and high mannose N-linked carbohydrates. These differences in the developmental onset and glycosylation suggest that nervous system-specific and muscle-specific connective tissue proteins are regulated differently and participate in different molecular interactions. © 1993 John Wiley & Sons, Inc.     

A Lectin from Chinese Mistletoe Increases γδ T Cell-mediated Cytotoxicity through Induction of Caspase-dependent Apoptosis

In this study, a mistletoe lectin (ML) was purified from Chinese mistletoe and the effect of this 60 kDa Chinese ML on human γδ T cell cytotoxicity, apoptosis and modulation of the cytokine network was studied. The cytotoxic properties of δ T cells was evaluated by using a ~(51)Cr release test and employed fluorescence-activated cell sorting and enzyme-linked immunosorbent assay analysis to quantify translocation of the cell membrane phospholipid, phosphatidylserine and nuclear DNA fragmentation during apoptosis. It was found that: (ⅰ) ML effectively stimulated γδ T cell proliferation in a dose- and time-dependent manner; (ⅱ) ML increased γδ T cell cytotoxicity; (ⅲ) ML could modulate lipopolysaccharide-induced cytokine release in a pro-inflammatory manner by increasing tumor necrosis factor (TNF)-α release and inhibiting the release of anti-inflammatory interleukin (IL)-10; (ⅳ) ML induced apoptosis in caspase-dependent and CD95-independent manner. The results indicated that ML is a potent immunomodulator to human γδ T cell cytotoxicity, apoptosis and cytokine production.     

Binding of different monosaccharides by lectin PA-IIL from Pseudomonas aeruginosa: thermodynamics data correlated with X-ray structures

The lectin from Pseudomonas aeruginosa (PA-IIL) is involved in host recognition and biofilm formation. Lectin not only displays an unusually high affinity for fucose but also binds to L-fucose, L-galactose and D-arabinose that differ only by the group at position 5 of the sugar ring. Isothermal calorimetry experiments provided precise determination of affinity for the three methyl-glycosides and revealed a large enthalpy contribution. The crystal structures of the complexes of PA-IIL with L-galactose and Met-beta-D-arabinoside have been determined and compared with the PA-IIL/fucose complex described previously. A combination of the structures and thermodynamics provided clues for the role of the hydrophobic group in affinity.     

Interactions of the fucose-specific Pseudomonas aeruginosa lectin, PA-IIL, with mammalian glycoconjugates bearing polyvalent Lewis(a) and ABH blood group glycotopes

Pseudomonas aeruginosa Fuc > Man specific lectin, PA-IIL, is an important microbial agglutinin that might be involved in P. aeruginosa infections in humans. In order to delineate the structures of these lectin receptors, its detailed carbohydrate recognition profile was studied both by microtiter plate biotin/avidin-mediated enzyme-lectin-glycan binding assay (ELLSA) and by inhibition of the lectin-glycan interaction. Among 40 glycans tested for binding, PA-IIL reacted well with all human blood group ABH and Le(a)/Le(b) active glycoproteins (gps), but weakly or not at all with their precursor gps and N-linked gps. Among the sugar ligands tested by the inhibition assay, the Le(a) pentasaccharide lacto-N-fucopentaose II (LNFP II, Galbeta1-3[Fucalpha1-4]GlcNAcbeta1-3Galbeta1-4Glc) was the most potent one, being 10 and 38 times more active than the Le(x) pentasaccharide (LNFP III, Galbeta1-4 [Fucalpha1-3]GlcNAcbeta1-3Galbeta1-4Glc) and sialyl Le(x) (Neu5Acalpha2-3Galbeta1-4[Fucalpha1-3] GlcNAc), respectively. It was 120 times more active than Man, while Gal and GalNAc were inactive. The decreasing order of PA-IIL affinity for the oligosaccharides tested was: Le(a) pentaose > or = sialyl Le(a) tetraose > methyl alphaFuc > Fuc and Fucalpha1-2Gal (H disaccharide)>2'-fucosyllactose (H trisaccharide), Le(x) pentaose, Le(b) hexaose (LNDFH I) and gluco-analogue of Le(y) tetraose (LDFT)>H type I determinant (LNFP I)>Le(x) trisaccharide (Galbeta1-4[Fucalpha1-3]GlcNAc) > sialyl Le(x) trisaccharide > Man > Gal, GalNAc, and Glc (inactive). The results presented here, in accordance with the crystal 3D structural data, imply that the combining site of PA-IIL is a small cavity-type best fitting Fucalpha1- with a specific shallow groove subsite for the remainder part of the Le(a) saccharides, and that polyvalent glycotopes enhance the reactivity. The Fuc > Man Ralstonia solanacearum lectin RSL, which resembles PA-IIL in sugar specificity, differs from it in it's better fit to the B and A followed by H oligosaccharides vs. Fuc, whereas, the second R. solanacearum lectin RS-IIL (the structural homologue of PA-IIL) binds Man > Fuc. These results provide a valuable information on PA-IIL interactions with mammalian glycoforms and the possible spectrum of attachment sites for the homing of this aggressive bacterium onto the target molecules. Such information might be useful for the antiadhesive therapy of P. aeruginosa infections.     

树突状细胞C型凝集素DC-SIGN在人肾炎组织和肾小管上皮细胞表达

DC-SIGN(DC-specificICAM-grabbingnon-integrin,亦称CD209)属树突状细胞(DC)表面C型凝集素的膜蛋白。作为DC黏附及模式识别受体,其参与介导了DC的炎症组织迁移,识别捕获病原微生物,以及随后激活静息T细胞启动的免疫应答。为此观察了DC-SIGN及DC-SIGN DC在肾炎患者肾组织中表达和分布,以及DC-SIGN在炎性状态下培养人肾小管上皮细胞表达,探讨与肾小管间质炎症病变和损伤的关系。结果显示,DC-SIGN在正常肾组织基本不表达,而在肾炎早期即以肾小管上皮细胞为主表达上调,且随肾小管间质病变程度加重表达增强(P<0.01),与肾小管间质病变程度明显相关(P<0.01)。此外,DC-SIGN在经TNF-α刺激炎性状态下的人肾小管上皮细胞也明显表达。进一步发现,DC-SIGN DC在肾炎早期以肾间质为主分布聚集,也随肾小管间质病变程度加重明显增多(P<0.01),与肾小管间质病变程度显著相关(P<0.01),也与DC-SIGN表达相关联(P<0.01)。另外,DC-SIGN DC在肾小管间质分布数量与肾炎患者肾功能改变明显相关(P<0.05)。研究结果提示,DC-SIGN也是肾小管间质早期炎症的启动参与因素,其介导DC可能也参与了人肾炎肾小管间质的免疫损伤机制。     

Purification and biological effects of Araucaria angustifolia (Araucariaceae) seed lectin

This paper describes the purification and characterization of a new N-acetyl-d-glucosamine-specific lectin from Araucaria angustifolia (AaL) seeds (Araucariaceae) and its anti-inflammatory and antibacterial activities. AaL was purified using a combination of affinity chromatography on a chitin column and ion exchange chromatography on Sephacel-DEAE. The pure protein has 8.0kDa (SDS-PAGE) and specifically agglutinates rabbit erythrocytes, effect that was independent of the presence of divalent cations and was inhibited after incubation with glucose and N-acetyl-d-glucosamine. AaL showed antibacterial activity against Gram-negative and Gram-positive strains, shown by scanning electron microscopy. AaL, intravenously injected into rats, showed anti-inflammatory effect, via carbohydrate site interaction, in the models of paw edema and peritonitis. This lectin can be used as a tool for studying bacterial infections and inflammatory processes.     

Identification and characterization of a novel human collectin CL-K1

Collectins are a family of C-type lectins with two characteristic structures, collagen like domains and carbohydrate recognition domains. They recognize carbohydrate antigens on microorganisms and act as host-defense. Here we report the cloning and characterization of a novel collectin CL-K1. RT-PCR analyses showed CL-K1 mRNA is present in all organs. The deduced amino acid sequence and the data from immunostaining of CL-K1 cDNA expressing CHO cells revealed that CL-K1 is expressed as a secreted protein. CL-K1 is found in blood by immunoblotting and partial amino acid analyses. CL-K1 showed Ca(2+)-dependent sugar binding activity of fucose and weakly mannose but not N-acetyl-galactosamine, N-acetyl-glucosamine, or maltose, though mannose-binding lectin (MBL) containing similar amino acid motif. CL-K1 can recognize specially several bacterial saccharides due to specific sugar-binding character. Elucidation of the role of two ancestor collectins of CL-K1 and CL-L1 could lead to see the biological function of collectin family.