Repression by a differentiation-specific factor of the human cytomegalovirus enhancer.

We detected a novel nuclear protein, MRF, that binds to multiple sites on the modulator which is located upstream of the human cytomegalovirus major immediate early gene enhancer. The expression of MRF is differentiation specific; the DNA binding activity is present in nuclear extracts from undifferentiated Tera-2 and THP-1 cells, but significantly reduced after these cells are induced to differentiate. In undifferentiated cells the enhancer activity is repressed by the modulator and upon differentiation the enhancer becomes active. Competitive binding assays demonstrate that MRF requires the presence of multiple A+T stretches for binding to DNA, rather than binding to a specific DNA sequence. Mutations of these stretches in the modulator reduce the binding activity of MRF, as well as the repressing activity on the enhancer. These results suggest that MRF may act as a repressor of enhancer function. We propose that MRF binds over the entire modulator and exerts repressor activity.     

Copper-induced trafficking of the Cu-ATPases: A key mechanism for copper homeostasis

The Menkes protein (MNK) and Wilson protein (WND) are transmembrane, CPX-type Cu-ATPases with six metal binding sites (MBSs) in the N-terminal region containing the motif GMXCXXC. In cells cultured in low copper concentration MNK and WND localize to the transGolgi network but in high copper relocalize either to the plasma membrane (MNK) or a vesicular compartment (WND). In this paper we investigate the role of the MBSs in Cu-transport and trafficking. The copper transport activity of MBS mutants of MNK was determined by their ability to complement a strain of Saccharomyces cerevisiae deficient in CCC2 (ccc2), the yeast MNK/WND homologue. Mutants (CXXC to SXXS) of MBS1, MBS6, and MBSs1-3 were able to complement ccc2 while mutants of MBS4-6, MBS5-6 and all six MBS inactivated the protein. Each of the inactive mutants also failed to display Cu-induced trafficking suggesting a correlation between trafficking and transport activity. A similar correlation was found with mutants of MNK in which various MBSs were deleted, but two constructs with deletion of MBS5-6 were unable to traffic despite retaining 25% of copper transport activity. Chimeras in which the N-terminal MBSs of MNK were replaced with the corresponding MBSs of WND were used to investigate the region of the molecules that is responsible for the difference in Cu-trafficking of MNK and WND. The chimera which included the complete WND N-terminus localized to a vesicular compartment, similar to WND in elevated copper. Deletions of various MBSs of the WND N-terminus in the chimera indicate that a targeting signal in the region of MBS6 directs either WND/MNK or WND to a vesicular compartment of the cell.     

Na+/Mg2+ transporter acts as a Mg2+ buffering mechanism in PC12 cells

Mg(2+) buffering mechanisms in PC12 cells were demonstrated with particular focus on the role of the Na(+)/Mg(2+) transporter by using a newly developed Mg(2+) indicator, KMG-20, and also a Na(+) indicator, Sodium Green. Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), a protonophore, induced a transient increase in the intracellular Mg(2+) concentration ([Mg(2+)](i)). The rate of decrease of [Mg(2+)](i) was slower in a Na(+)-free extracellular medium, suggesting the coupling of Na(+) influx and Mg(2+) efflux. Na(+) influxes were different for normal and imipramine- (a putative inhibitor of the Na(+)/Mg(2+) transporter) containing solutions. FCCP induced a rapid increase in [Na(+)](i) in the normal solution, while the increase was gradual in the imipramine-containing solution. The rate of decrease of [Mg(2+)](i) in the imipramine-containing solution was also slower than that in the normal solution. From these results, we show that the main buffering mechanism for excess Mg(2+) depends on the Na(+)/Mg(2+) transporter in PC12 cells.     

Dual effect of chemokine CCL7/MCP-3 in the development of renal tubulointerstitial fibrosis

Most end-stage renal disease kidneys display accumulation of extracellular matrix (ECM) in the renal tubular compartment (tubular interstitial fibrosis – TIF) which is strongly correlated with the future loss of renal function. Although inflammation is a key event in the development of TIF, it can also have a beneficial anti-fibrotic role depending in particular on the stage of the pathology. Chemokines play an important role in monocyte extravasation in the inflammatory process. CCL2 has already been shown to be involved in the development of TIF but CCL7, a close relative of CCL2 and able to bind to similar receptors, has not been studied in renal disease. We therefore studied chemokine CCL7 in a model of unilateral ureteral obstruction (UUO)-induced TIF. We observed that the role of CCL7 differs depending on the stage of the pathology. In early stages (0–8 days), CCL7 deficient (CCL7-KO) mice displayed attenuated TIF potentially involving two mechanisms: an early (0–3 days) decrease of inflammatory cell infiltration followed (3–8 days) by a decrease in tubular ECM production independent of inflammation. In contrast, during later stages of obstruction (10–14 days), CCL7-KO mice displayed increased TIF which was again associated with reduced inflammation. Interestingly, the switch between this anti- to profibrotic effect was accompanied by an increased influx of immunosuppressive regulatory T cells. In conclusion, these results highlight for the first time a dual role for CCL7 in the development of renal TIF, deleterious in early stages but beneficial during later stages.     

Identification and SAR of squarate inhibitors of mitogen activated protein kinase-activated protein kinase 2 (MK-2)

A novel series of inhibitors for mitogen activated protein kinase-activated protein kinase 2 (MK-2) are reported. These squarate based inhibitors were identified via a high-throughput screen. An MK2 co-structure with the starting ligand was obtained and a structure based approach was followed to optimize potency and selectivity.     

Histological Observations on Initiation and Morphogenesis in Immature and Mature Embryo Derived Callus of Barley (Hordeum vulgare L.)

Callus was induced from immature and mature embryos of barley(cv. Haruna Nijo) on Murashige and Skoog medium containing 2mg l^-1 2,4-D and 5 mg l^-1 picloram, respectively. Paraffin sections(10 µm thick) were prepared for histology during callusinitiation and plant regeneration. Meristems were regeneratedfrom nodular compact callus (NC) derived from scutellar epidermisin immature embryos, whereas they were regenerated from NC derivedfrom epidermal cells of leaf or coleoptile bases in mature embryos.Regardless of the explant source, regeneration was predominantlythrough organogenesis, although regeneration through somaticembryogenesis infrequently occurred. Thus, the callus inducedfrom immature and mature embryos of barley was regarded as 'nodularcompact' rather than 'embryogenic'.Copyright 1995, 1999 AcademicPress Barley, callus, Hordeum vulgare, histology, immature embryo, mature embryo, regeneration     

Intracistronic mapping of the defective site and the biochemical properties of beta subunit mutants of Escherichia coli H+-ATPase: correlation of structural domains with functions of the beta subunit

Sixteen mutants of Escherichia coli defective in H+-ATPase (proton-translocating ATPase) were tested for their ability to recombine with hybrid plasmids carrying various portions of the beta subunit cistron. Twelve mutations were mapped within the carboxyl half of the cistron corresponding to amino acid residues 279 to 459 (domain II), while four mutations were mapped within residues 17 to 278 (domain I). The biochemical properties of these mutants were analyzed in terms of the proton permeability of their membranes and the assembly properties of their F1F0 complex. The mutants were classified according to the properties into three types, I, II, and III. In 12 mutants of type I, proton conduction in membrane vesicles was blocked and little F1 was released from the membranes under conditions in which F1 could be released from wild-type membranes, suggesting that assembly of the F1F0 complex is structurally and functionally defective. F1 was partially purified with very low recovery from one of the type I mutants, KF16. ATPase activity was reconstituted from this F1 with the beta subunit of the wild type, confirming the genetic results. Only one mutant, KF38, was classified as type II. Its membranes were partially leaky to protons and its F1 was releasable, suggesting that the interaction of its F1 and F0 was unstable. Type III mutants, KF11 and KF43, had an F1F0 complex with very low activity, in which the structure of F1 was relatively similar to that of the wild type. F1 was purified as a single complex from KF43 in this study and from KF11 previously (H. Kanazawa, Y. Horiuchi, M. Takagi, Y. Ishino, and M. Futai (1980) J. Biochem. 88, 695-703). Reconstitution experiments in vitro showed that the F1's of both mutants were defective in the beta subunit. The properties of the altered F1 of KF43 differed from those of F1 of KF11, suggesting that the mutation sites of KF43 and KF11 were different. From the results of mapping mutation sites and the biochemical properties of the mutants, the correlation of structural domains with function of the beta subunit is discussed. Most type I and type II mutations except that of KF39 were mapped in domain II, while the type III mutations were mapped in domain I, suggesting that domain II is more important than domain I for the function of the beta subunit, especially in terms of proper assembly of the F1F0 complex.     

Immunogold Localisation of the Intermediate Chain within the Protein Complex of Cytoplasmic Dynein

It was our goal to determine the location of the intermediate chain within the complex of cytoplasmic dynein by immunoelectron microscopy. To do so we generated two monoclonal antibodies (m74-1 and m74-2) specific for the intermediate chain. Both antibodies recognised the intermediate chain by sodium dodecyl sulphate–polyacrylamide gel electrophoresis immunoblot and ELISA assays of native and denatured proteins. When sucrose density gradient-purified cytoplasmic dynein from bovine brain was incubated with the gold-conjugated monoclonal antibodies, m74-1 and m74-2, and examined by negative staining, the gold label was found opposite the globular heads at the base of the V-shaped stalk of the motor complex. The labelling of the intermediate chain is the first mapping of a component within cytoplasmic dynein. The identification of the intermediate chain at the base of the complex supports a possible docking function of the intermediate chain.     

Omega-3 fatty acids and neuropsychiatric disorders

Epidemiological evidence suggests that dietary consumption of the long chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), commonly found in fish or fish oil, may modify the risk for certain neuropsychiatric disorders. As evidence, decreased blood levels of omega-3 fatty acids have been associated with several neuropsychiatric conditions, including Attention Deficit (Hyperactivity) Disorder, Alzheimer's Disease, Schizophrenia and Depression. Supplementation studies, using individual or combination omega-3 fatty acids, suggest the possibility for decreased symptoms associated with some of these conditions. Thus far, however, the benefits of supplementation, in terms of decreasing disease risk and/or aiding in symptom management, are not clear and more research is needed. The reasons for blood fatty acid alterations in these disorders are not known, nor are the potential mechanisms by which omega-3 fatty acids may function in normal neuronal activity and neuropsychiatric disease prevention and/or treatment. It is clear, however, that DHA is the predominant n-3 fatty acid found in the brain and that EPA plays an important role as an anti-inflammatory precursor. Both DHA and EPA can be linked with many aspects of neural function, including neurotransmission, membrane fluidity, ion channel and enzyme regulation and gene expression. This review summarizes the knowledge in terms of dietary omega-3 fatty acid intake and metabolism, as well as evidence pointing to potential mechanisms of omega-3 fatty acids in normal brain functioning, development of neuropsychiatric disorders and efficacy of omega-3 fatty acid supplementation in terms of symptom management.