Macroautophagy--a novel Beta-amyloid peptide-generating pathway activated in Alzheimer's disease

Macroautophagy, which is a lysosomal pathway for the turnover of organelles and long-lived proteins, is a key determinant of cell survival and longevity. In this study, we show that neuronal macroautophagy is induced early in Alzheimer's disease (AD) and before beta-amyloid (Abeta) deposits extracellularly in the presenilin (PS) 1/Abeta precursor protein (APP) mouse model of beta-amyloidosis. Subsequently, autophagosomes and late autophagic vacuoles (AVs) accumulate markedly in dystrophic dendrites, implying an impaired maturation of AVs to lysosomes. Immunolabeling identifies AVs in the brain as a major reservoir of intracellular Abeta. Purified AVs contain APP and beta-cleaved APP and are highly enriched in PS1, nicastrin, and PS-dependent gamma-secretase activity. Inducing or inhibiting macroautophagy in neuronal and nonneuronal cells by modulating mammalian target of rapamycin kinase elicits parallel changes in AV proliferation and Abeta production. Our results, therefore, link beta-amyloidogenic and cell survival pathways through macroautophagy, which is activated and is abnormal in AD.     

Actinomycetes as host cells for production of recombinant proteins

Actinomycetes (Actinobacteria) are highly attractive as cell factories or bioreactors for applications in industrial, agricultural, environmental, and pharmaceutical fields. Genome sequencing of several species of actinomycetes has paved the way for biochemical and structural analysis of important proteins and the production of such proteins as recombinants on a commercial scale. In this regard, there is a need for improved expression vectors that will be applicable to actinomycetes. Recent advancements in gene expression systems, knowledge regarding the intracellular environment, and identification and characterization of plasmids has made it possible to develop practicable recombinant expression systems in actinomycetes as described in this review.     

In situ control of cell adhesion using photoresponsive culture surface

A photoresponsive culture surface (PRCS) allowing photocontrol of cell adhesion was prepared with a novel polymer material composed of poly(N-isopropylacrylamide) having spiropyran chromophores as side chains. Cell adhesion of the surface was drastically enhanced by the irradiation with ultraviolet (UV) light (wavelength: 365 nm); after subsequent cooling and washing on ice, many cells remained in the irradiated region, whereas most cells were removed from the nonirradiated region. The cell adhesion of the PRCS, which had been enhanced by previous UV irradiation, was reset by the visible light irradiation (wavelength 400-440 nm) and the annealing at 37 degrees C for 2 h. Also it was confirmed that the regional control of cell adhesion was induced several times by repeating the same series of operations. Further, living cell patterning with the 200 microm line width was produced readily by projecting UV light along a micropattern on the PRCS on which the living cells had been seeded uniformly in advance. By using a fluorescent probe that stains living cells only, it was confirmed that the cells maintained sufficient viability even after UV light irradiation followed by cooling and washing.     

Pharmacological properties of angiotensin II receptors in cultured rabbit gingival fibroblasts

Certain interspecific hybrids of the fish Xiphophorus spontaneously develop melanoma induced by the derepression of the Xmrk oncogene. Xmrk is a recent duplicate of an orthologue of the mammalian epidermal growth factor receptor gene Egfr. In addition to a specific overexpression in melanoma, amino-acid substitutions in the extracellular domain leading to ligand-independent dimerisation and constitutive autophosphorylation are responsible for the tumorigenic potential of Xmrk. The Xmrk receptor induces several signal transduction pathways mediating cell proliferation and resistance to apoptosis and initiating dedifferentiation. Moreover, Xmrk upregulates the expression of the secreted protein osteopontin, inducing an autocrine loop possibly allowing invasion and survival in the dermis as a first step in malignancy. Hence, Xmrk is able to induce pathways essential for a transformed phenotype. Some of these events are equivalent to those found downstream of the mammalian Egfr, but others have clearly evolved differently or are specific for pigment cells. Xmrk is potentially hazardous, nonessential and located in a very unstable genomic region. Nevertheless, Xmrk has been maintained under purifying selection in divergent Xiphophorus species. Hence, Xmrk has probably a beneficial function under certain conditions. The analysis of this function is a major challenge for future research in the Xiphophorus model.     

Distributed Shared Arrays: Portable Shared-Memory Programming Interface for Multiple Computer Systems

This paper describes the design and implementation of a parallel programming environment called Distributed Shared Array (DSA), which provides a shared global array abstract across different machines connected by a network. In DSA, users can define and use global arrays that can be accessed uniformly from any machines in the network. Explicit management of array area allocation, replication, and migration is achieved by explicit calls for array manipulation: defining array regions, reading and writing array regions, synchronization, and control of replication and migration. The DSA is integrated with Grid (Globus) services. This paper also describes the use of our model for gene cluster analysis, multiple alignment and molecular dynamics simulation. In these applications, global arrays are used for storing the distance matrix, alignment matrix and atom coordinates, respectively. Large array areas, which cannot be stored in the memory of individual machines, are made available by the DSA. Scalable performance of DSA was obtained compared to that of conventional parallel programs written in MPI.     

Peroxynitrite scavenging activities of aromatic compounds isolated from Konnyaku,Amorphophallus konjac K.Koch

(+/-)-5,5'-Dimethoxysesamin, erythrinasinate, indole-3-carbaldehyde, (7R,8S)-dihydrodehydrodiconiferyl alcohol 9-O-beta-D-glucopyranoside, cis- and trans-N-(p-coumaroyl)serotonin, serotonin, 3,4-dihydroxybenzoic acid, and 3,4-dihydroxybenzaldehyde have been found in tobiko, a food by-product, and evaluation of their peroxynitrite scavenging activities has been done. Among these compounds, serotonin, trans-N-(p-coumaroyl)serotonin, 3,4-dihydroxybenzaldehyde, and 3,4-dihydroxybenzoic acid showed stronger activities than that of BHT (butylated hydroxytoluene) at 200 microM.     

Purification and characterization of pyridoxal 4-dehydrogenase from Aureobacterium luteolum

A pyridoxal dehydrogenase was purified to homogeneity from Aureobacterium luteolum, which can use pyridoxine as a carbon and nitrogen source, and characterized. The enzyme was a dimeric protein with a subunit molecular weight of 38,000. It had several properties distinct from those of the partially purified enzyme from Pseudomonas MA-1. The optimum pH (8.0-8.5) was 0.8-1.3 lower than that of the Pseudomonas enzyme. The Aureobacterium enzyme showed much higher and lower affinities for NAD+ (Km, 0.140 +/- 0.008 mM) and pyridoxal (0.473 +/- 0.109 mM), respectively, than those of the Pseudomonas enzyme. The Aureobacterium enzyme could use NADP+ as a substrate: the reactivity was 6.5% of NAD+. The enzyme was much more tolerant to metal-chelating agents. Irreversibility of the enzymatic reaction was shared by the two enzymes. No aldehyde dehydrogenase showed similarity to the amino-terminal amino acid sequence of the enzyme.     

Restricted clinical efficacy of cyclosporin A on rat transient middle cerebral artery occlusion

The immunosuppressant cyclosporin A (CsA) has been shown to have neuroprotective action. The inhibition of both calcineurin activation and mitochondrial permeability transition pore (mtPTP) opening are considered the primary neuroprotective mechanisms of CsA. Here we have evaluated the effect of CsA on significantly reducing infarct size induced by transient middle cerebral artery occlusion (MCAO) in rats, and examined variable therapeutic applications for brain infarction. Experimental rats were divided into 12 groups according to: CsA administration time (immediately after occlusion or immediately after reperfusion); dosage (between 10 and 50 mg/kg); route (i.v. or i.p.); and with or without needle insertion, which hypothetically disrupts the blood brain barrier (BBB). Neuroprotective effects of CsA were hardly noticeable when administered immediately after occlusion or by i.v. injection. By needle insertion, CsA administration significantly reduced infarct size, although vehicle treatment also reduced infarct size compared with nontreatment animals, i.e. no needle insertion. These results suggest that needle insertion allows endogenous neuroprotective substances to pass into the brain. Furthermore, single dosages over 30 mg/kg CsA were excessive and negated potential neuroprotective effects. However, two i.p. administrations of 20 mg/kg CsA immediately and 24 hrs after reperfusion significantly ameliorated the infarct size compared to the vehicle-treated group. We conclude that CsA exhibits significant neuroprotective activity, although its therapeutic application for stroke may be limited by very strict and precise management requirements.     

ATP binding and hydrolysis and autophosphorylation of CbbQ encoded by the gene located downstream of RubisCO genes

CbbQ is encoded by the gene located downstream of ribulose 1,5-bisphosphate carboxylase/oxygenase genes (cbbLS) in the thermophilic hydrogen-oxidizing bacterium, Hydrogenophilus thermoluteolus. The protein possesses two nucleotide-binding motifs in its amino acid sequence, and it posttranslationally activates RubisCO. We present ATP hydrolysis and binding of CbbQ. CbbQ releases P(i) from ATP only in the presence of Mg(2+). CbbQ interacts with an 2'(3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate in the presence or absence of Mg(2+). The interaction with Mg(2+) and/or a nucleotide induces a conformational change in CbbQ. Autophosphorylation of CbbQ occurs only in the absence of Mg(2+).