Activation by GTP of liver adenylate cyclase in the presence of high concentrations of ATP

Effect of GTP on adenylate cyclase of liver plasma membrane was examined using ATP which was extensively purified by DEAE-cellulose column chromatography. In the incubation containing 2mM purified ATP as substrate, GTP enhanced basal and glucagon- or fluoride-stimulated activities. When the unpurified ATP at 2mM was used, all the activities were high and the stimulatory effect of GTP was not detected. The substance(s) which was recovered from a small but significant peak on DEAE-cellulose column was equivalent to 10–100μM GTP in stimulating adenylate cyclase. These results indicate that, if highly purified ATP is used as substrate, GTP can enhance adenylate cyclase activity in the presence of millimolar concentration of ATP and that GTP enhances not only the glucagon-stimulated adenylate cyclase but also the basal as well as fluoride-stimulated adenylate cyclase activities.     

Enhanced validation of small-molecule ligands and carbohydrates in the Protein Data Bank

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Isolation of tissue progenitor cells from duct-ligated salivary glands of swine

Tissue stem cells participate in the repopulation of tissue after injury. Tissue injury stimulates the normally quiescent tissue stem cells to differentiate and proliferate, in the process of replacing and/or repairing the damaged cells, and hence effecting tissue regeneration. The salivary glands retain the ability for frequent regeneration. Previously, we isolated progenitor cells from the injured salivary glands of mice and rats that differentiated into hepatic and pancreatic lineages. The isolated progenitors were CD49f-positive and intracellular laminin-positive, and proliferated on type I collagen while maintaining their multipotency. In this study, we analyzed the tissue stem cells induced by ligating the main excretory duct of the salivary gland in swine. After duct ligation of the gland, acinar cells receded due to apoptosis, and epithelial cells subsequently proliferated. We cultured cells obtained from the duct-ligated salivary gland and purified the cells by limited dilution. The isolated cells were positive for CD29, CD49f, intracellular laminin, AFP, CK19, CK18, and Thy-1(CD90), and weakly positive for c-Kit (CD117). After three-dimensional formation, the cells expressed insulin and albumin. We designated the cells as swine salivary gland-derived progenitor cells. Gene expression of insulin and albumin was significantly increased (five-fold) and that of insulin was also increased (3.8-fold) with differentiation medium with nicotinamide and/or GLP-1 treatment in spherical culture. The expressions of albumin and insulin were 1/10-fold and 1/4-fold compared to porcine hepatocytes and pancreatic endocrine cells. The differentiated SGP cells could release insulin, which were stimulated by glucose and potassium. These results indicate that swine SGP cells could differentiate into hepatocytes and beta-cells, functionally. Swine SGP cells were useful tools for therapy and analyzing endodermal regenerative models in large animals.     

Molecular characterization the <Emphasis Type="Italic">YABBY</Emphasis> gene family in <Emphasis Type="Italic">Oryza sativa</Emphasis> and expression analysis of <Emphasis Type="Italic">OsYABBY1</Emphasis>

Members of the YABBY gene family have a general role that promotes abaxial cell fate in a model eudicot, Arabidopsis thaliana. To understand the function of YABBY genes in monocots, we have isolated all YABBY genes in Oryza sativa (rice), and revealed the spatial and temporal expression pattern of one of these genes, OsYABBY1. In rice, eight YABBY genes constitute a small gene family and are classified into four groups according to sequence similarity, exon-intron structure, and organ-specific expression patterns. OsYABBY1 shows unique spatial expression patterns that have not previously been reported for other YABBY genes, so far. OsYABBY1 is expressed in putative precursor cells of both the mestome sheath in the large vascular bundle and the abaxial sclerenchyma in the leaves. In the flower, OsYABBY1 is specifically expressed in the palea and lemma from their inception, and is confined to several cell layers of these organs in the later developmental stages. The OsYABBY1-expressing domains are closely associated with cells that subsequently differentiate into sclerenchymatous cells. These findings suggest that the function of OsYABBY1 is involved in regulating the differentiation of a few specific cell types and is unrelated to polar regulation of lateral organ development.     

The influence of visual display terminal use on the physical and mental conditions of administrative staff in Japan

Visual display terminals (VDT) are standard equipment for many office workers. Their use, however, may increase the risk of developing adverse conditions related to vision, the musculoskeletal system, and mental health. We carried out a survey among 3070 workers aged 18 to 67 years (mean, 39.9 years) at a prefectural administrative office, in which 76% of subjects were visual display terminal (VDT) users. We examined the relationship between duration of daily VDT use and eyestrain, neck or upper extremity pain, back pain, and mental health, and estimated the effect of breaks and rest during VDT work on these symptoms. The 12-item General Health Questionnaire (GHQ-12: total scores ranged from 0 to 12) was used to identify potential poor mental health status, and subjects with 4 or more were considered to have symptoms of psychological distress. Seventeen percent of subjects reported eyestrain, 19.1% reported upper extremity pain, 11.6% reported back pain, and 17% of subjects had GHQ-12 scores of 4 or higher. Logistic regression analysis showed that duration of daily VDT use and lack of breaks and rest during VDT work were significantly associated with eyestrain, neck or upper extremity pain, back pain, and psychological distress. In order to protect users from the adverse effects associated with VDT work, reducing daily VDT exposure, taking breaks, and rest during VDT work are important.     

Activated somatostatin type 2 receptors traffic in vivo in central neurons from dendrites to the trans Golgi before recycling

Understanding the trafficking of G-protein-coupled receptors (GPCRs) is of particular importance, especially when modifications of the neurochemic environment occur as in pathological or therapeutic circumstances. In the central nervous system, although some GPCRs were reported to internalize in vivo, little is known about their trafficking downstream of the endocytic event. To address this issue, distribution and expression pattern of the major somatostatin receptor subtype, the somatostatin type 2 (sst2), was monitored in the hippocampus using immunofluorescence, autoradiographic and immunogold experiments from 10 minutes to 7 days after in vivo injection of the receptor agonist octreotide. We then analyzed whether postendocytic trafficking of the receptor was dependent upon integrity of the microtubule network using colchicine-injected animals. Together, our results suggest that upon agonist stimulation, dendritic receptors are retrogradely transported through a microtubule-dependent mechanism to a trans Golgi domain enriched in the t-SNARE syntaxin 6 and trans Golgi network 38 proteins, before recycling. Because we show that the exit rate from the trans Golgi apparatus back to the plasma membrane (hours) is slower than the entry rate (minutes), the neuronal postendocytic trafficking of sst2 receptor is likely to have functional consequences in several neurological diseases in which an increase in somatostatin release occurs.     

Cats as a potential source of emerging influenza virus infections

<正>Dear Editor,Historically,the influenza virus has not been regarded as a major pathogen of cats.However,since 2003,natural infections of domestic cats with highly pathogenic H5N1 avian virus causing fatal cases have been reported(Songserm et al.,2006;Yingst et al.,2006;Klopfleisch et al.,2007).Furthermore,infections of this animal with A(H1N1)pdm09 virus,causing respiratory illness with some fatal cases,have also been reported in various parts     

Specific recognition of linear polyubiquitin by A20 zinc finger 7 is involved in NF-κB regulation

LUBAC (linear ubiquitin chain assembly complex) activates the canonical NF-κB pathway through linear polyubiquitination of NEMO (NF-κB essential modulator, also known as IKKγ) and RIP1. However, the regulatory mechanism of LUBAC-mediated NF-κB activation remains elusive. Here, we show that A20 suppresses LUBAC-mediated NF-κB activation by binding linear polyubiquitin via the C-terminal seventh zinc finger (ZF7), whereas CYLD suppresses it through deubiquitinase (DUB) activity. We determined the crystal structures of A20 ZF7 in complex with linear diubiquitin at 1.70–1.98 Å resolutions. The crystal structures revealed that A20 ZF7 simultaneously recognizes the Met1-linked proximal and distal ubiquitins, and that genetic mutations associated with B cell lymphomas map to the ubiquitin-binding sites. Our functional analysis indicated that the binding of A20 ZF7 to linear polyubiquitin contributes to the recruitment of A20 into a TNF receptor (TNFR) signalling complex containing LUBAC and IκB kinase (IKK), which results in NF-κB suppression. These findings provide new insight into the regulation of immune and inflammatory responses.