Design,synthesis and structure-activity relationships of dual inhibitors of acetylcholinesterase and serotonin transporter as potential agents for Alzheimer's disease

We have designed and synthesized a dual inhibitor of acetylcholinesterase (AChE) and serotonin transporter (SERT) as a novel class of treatment drugs for Alzheimer's disease on the basis of a hypothetical model of the AChE active site. Dual inhibitions of AChE and SERT would bring about greater therapeutic effects than AChE inhibition alone and avoid adverse peripheral effects caused by excessive AChE inhibition. Compound (S)-6j exhibited potent inhibitory activities against AChE (IC(50)=101 nM) and SERT (IC(50)=42 nM). Furthermore, (S)-6j showed inhibitory activities of both AChE and SERT in mice brain following oral administration.     

The rainbow trout classical MHC class I molecule Onmy-UBA*501 is expressed in similar cell types as mammalian classical MHC class I molecules

Onmy-UBA is a polymorphic classical major histocompatibility (MHC) class I locus in rainbow trout (Oncorhynchus mykiss). A common allomorph is Onmy-UBA*501, which has been detected in several wildtype strains, in the clonal homozygous rainbow trout C25 and, in the current study, in the rainbow trout gonad cell line RTG-2. The extracellular domain of this allomorph was expressed in E. coli and a murine monoclonal antibody designated H9 was generated against the recombinant protein. In Western blot analysis Mab H9 specifically recognised an n-glycosylated protein of 45 kDa in leucocytes and erythrocytes of C25 fish and in RTG-2 cells. The level of Onmy-UBA*501 expression in erythrocytes was very low. Immunocytochemistry of isolated cells indicated expression in lymphocytes, macrophages, neutrophils, erythrocytes, RTG-2 cells and Onmy-UBA *501 transfected CHO cells, but not in untransfected CHO cells. Immunohistochemistry using frozen sections of C25 fish indicated that Onmy-UBA*501 expression is strong in the lymphoid organs (thymus, head kidney and spleen) and in the epithelia and endothelia of several organs. No significant expression was observed in muscle fibres, hepatocytes or neurons. These observations demonstrate that in jawed fish, the lowest phylogenetic group possessing an MHC system, the classical MHC class I molecules are expressed in similar cell types as in higher vertebrates.     

T-588 Protects Motor Neuron Death Against Glutamate-Induced Neurotoxicity

To examine the possible neuroprotective effect of T-588 against glutamate-induced neurotoxicity, we analyzed the pharmacological utility of T-588 in a postnatal organotypic culture model of motor neuron degeneration. Treatment with 10^–5 M of glutamate resulted a motor neuron loss and decreased activity of choline acetyltransferase (ChAT). Cotreatment of 10^–5 M of glutamate and T-588 revealed a protective effect against motor neuron death and decreased ChAT activity. We concluded that T-588 may play important roles in the survival and maintenance of spinal motor neurons in its neuroprotection against glutamate-induced neurotoxicity. Our data may provide a rationale for designing a therapeutic strategy for protection against pathologically induced motor neuron damage or cell death such as amyotrophic lateral sclerosis and motor neuropathy.     

Oligomerization process of the hemolytic lectin CEL-III purified from a sea cucumber, Cucumaria echinata

CEL-III is a Ca(2+)-dependent lectin purified from a sea cucumber, Cucumaria echinata. This protein exhibits strong hemolytic activity as well as cytotoxicity toward some cultured cell lines. Hemolysis is caused by CEL-III oligomers formed in the cell membrane after binding to specific carbohydrate chains on the cell surface. We have found that the oligomerization of CEL-III is also induced by the binding of simple carbohydrates, such as lactose, in aqueous solution under high pH and high ionic strength conditions. From gel filtration analysis of the oligomerization of CEL-III, it was found that the formation of the CEL-III oligomer is effectively induced by the binding of lactose and lactulose, disaccharides containing a beta-galactoside structure. Electron micrographs of the resulting oligomers revealed them to exist as particles with a size of approximately 20-30 nm. The oligomerization process required more than 1 h, which is consistent with the increase in surface hydrophobicity as measured using a fluorescent probe, 8-anilinonaphthalene-1-sulfonate. However, a change in the far-UV CD spectra as well as small-angle X-ray scattering occurred within a few minutes, suggesting that a structural change in the protein takes place rapidly, but the following growth of the oligomer is a much slower process.     

Flap endonuclease 1 efficiently cleaves base excision repair and DNA replication intermediates assembled into nucleosomes

Flap Endonuclease 1 (FEN1) plays important roles both in DNA replication and in base excision repair (BER). However, in both processes FEN1 substrates are likely to be assembled into chromatin. In order to examine how FEN1 is able to work within chromatin, we prepared model nucleosome substrates containing FEN1-cleavable DNA flaps. We find that human FEN1 binds and cleaves such substrates with efficiencies similar to that displayed with naked DNA. Moreover, we demonstrate that both FEN1 and human DNA ligase I can operate successively on DNA within the same nucleosome. These results suggest that some BER steps may not require nucleosome remodeling in vivo and that FEN 1 activity during Okazaki fragment processing can occur on nucleosomal substrates.     

Encoding mechanisms for sensory neurons studied with a multielectrode array in the cat dorsal root ganglion

Recent advances in microelectrode array technology now permit a direct examination of the way populations of sensory neurons encode information about a limb's position in space. To address this issue, we recorded nerve impulses from about 100 single units simultaneously in the L6 and L7 dorsal root ganglia (DRG) of the anesthetized cat. Movement sensors, placed near the hip, knee, ankle, and foot, recorded passive movements of the cat's limb while it was moved pseudo-randomly. The firing rate of the neurons was correlated with the position of the limb in various coordinate systems. The firing rates were less correlated to the position of the foot in Cartesian coordinates (x, y) than in joint angular coordinates (hip, knee, ankle), or in polar coordinates. A model was developed in which position and its derivatives are encoded linearly, followed by a nonlinear spike-generating process. Adding the nonlinear portion significantly increased the correlations in all coordinate systems, and the full models were able to accurately predict the firing rates of various types of sensory neurons. The observed residual variability is captured by a simple stochastic model. Our results suggest that compact encoding models for primary afferents recorded at the DRG are well represented in polar coordinates, as has previously been suggested for the cortical and spinal representation of movement. This study illustrates how sensory receptors encode a sense of limb position, and it provides a general framework for modeling sensory encoding by populations of neurons.     

Highly specific marker genes for detecting minimal gastric cancer cells in cytology negative peritoneal washings

Peritoneal wash cytology plays a pivotal role in the decision for gastric cancer treatment because advanced gastric cancer often turns out incurable with peritoneal metastasis. Molecular detection of minimal cancer cells from peritoneal washings may overcome the sensitivity boundary of conventional cytology and contribute to the prediction of the disease outcome. To select marker candidates out of ten thousands of genes, we performed microarray analyses in 12 gastric cell lines and 8 peritoneal washings of early stage cases. With 40 candidates selected by the above expression profiling, RT-PCR in 16 representative peritoneal wash samples was performed to identify genes specific to cytology positive samples. The finally selected five genes, CK20, FABP1, MUC2, TFF1, and TFF2, were then evaluated for their utility as a marker for minimal residual disease in 99 peritoneal wash samples. Nested RT-PCR using the five genes showed positive results highly specific to incurable cases (91-100%). With a high specificity, the combination of these five genes succeeded in identifying 6 out of 20 (30%) additional patients with all types of early recurrence that could not be predicted by the conventional method. The six newly identified recurrences included four non-peritoneal ones, showing that RT-PCR using the five genes without a real-time quantitative PCR technique contributes to the detection of minimal residual disease.     

Characterization of recombinant CEL-I, a GalNAc-specific C-type lectin, expressed in Escherichia coli using an artificial synthetic gene

CEL-I is a C-type lectin isolated from the Holothuroidea Cucumaria echinata. This lectin shows very high N-acetylgalactosamine-binding specificity. We constructed an artificial gene encoding recombinant CEL-I (rCEL-I) using a combination of synthetic oligonucleotides, and expressed it in Escherichia coli cells. Since the recombinant protein was obtained as inclusion bodies, the latter were solubilized using urea and 2-mercaptoethanol, and the protein was refolded during the purification and dialysis steps. The purified rCEL-I showed comparable hemagglutinating activity to that of native CEL-I at relatively high Ca(2+)-concentrations, whereas it was weaker at lower Ca(2+)-concentrations due to decreased Ca(2+)-binding affinity. rCEL-I exhibited similar carbohydrate-binding specificity to native CEL-I, including strong GalNAc-binding specificity, as examined by hemagglutination inhibition assay. Comparison of the far UV-CD spectra of recombinant and native CEL-I revealed that the two proteins undergo a similar conformational change upon binding of Ca(2+). Single crystals of rCEL-I were also obtained under the same conditions as those used for the native protein, suggesting that they have similar tertiary structures. Although native CEL-I exhibited strong cytotoxicity toward cultured cells, rCEL-I showed low cytotoxicity. These results indicate that rCEL-I has a tertiary structure and carbohydrate-binding specificity similar to those of native CEL-I. Howeger, there is a subtle difference in the properties between the two proteins probably due to the additional methionine residue at the N-terminus of rCEL-I.     

Temperature-responsive cell culture surfaces enable "on-off" affinity control between cell integrins and RGDS ligands

In this study, specific interactions between immobilized RGDS (Arg-Gly-Asp-Ser) cell adhesion peptides and cell integrin receptors located on cell membranes are controlled in vitro using stimuli-responsive polymer surface chemistry. Temperature-responsive poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (P(IPAAm-co-CIPAAm)) copolymer grafted onto tissue culture grade polystyrene (TCPS) dishes permits RGDS immobilization. These surfaces facilitate the spreading of human umbilical vein endothelial cells (HUVECs) without serum depending on RGDS surface content at 37 degrees C (above the lower critical solution temperature, LCST, of the copolymer). Moreover, cells spread on RGDS-immobilized surfaces at 37 degrees C detach spontaneously by lowering culture temperature below the LCST as hydrated grafted copolymer chains dissociate immobilized RGDS from cell integrins. These cell lifting behaviors upon hydration are similar to results using soluble RGDS in culture as a competitive substitution for immobilized ligands. Binding of cell integrins to immobilized RGDS on cell culture substrates can be reversed spontaneously using mild environmental stimulation, such as temperature, without enzymatic or chemical treatment. These findings are important for control of specific interactions between proteins and cells, and subsequent "on-off" regulation of their function. Furthermore, the method allows serum-free cell culture and trypsin-free cell harvest, essentially removing mammalian-sourced components from the culture process.