Physiological copper exposure in Jurkat cells induces changes in the expression of genes encoding cholesterol biosynthesis proteins

Copper is an essential micronutrient that functions as an enzymatic cofactor in a wide range of cellular processes. Although adequate Cu levels are essential for normal metabolism, excess Cu can be toxic to cells. Cellular responses to copper deficiency and overload involve changes in the expression of genes directly and indirectly involved in copper metabolism. However little is known on the effect of physiological copper concentration on gene expression changes. In the current study we aimed to establish whether the expression of genes encoding enzymes related to cholesterol (hmgcs1, hmgcr, fdft) and fatty acid biosynthesis and LDL receptor can be induced by an iso-physiological copper concentration. The iso-physiological copper concentration was determined as the bioavailable plasmatic copper in a healthy adult population. In doing so, two blood cell lines (Jurkat and THP-1) were exposed for 6 or 24 h to iso- or supraphysiological copper concentrations. Our results indicated that in cells exposed to an iso-physiological copper concentration the early induction of genes involved in lipid metabolism was not mediated by copper itself but by the modification of the cellular redox status. Thus our results contributed to understand the involvement of copper in the regulation of cholesterol metabolism under physiological conditions.     

Copper exposure modifies the content and distribution of trace metals in mammalian cultured cells

With this work, we have determined the cellular content of Cu, Fe and Zn in different cell lines, by using total reflection X-ray fluorescence spectrometry (TXRF). In addition, we examined whether cellular exposure to 100 moles l^–1 of Cu-His modifies the intracellular content and distribution of these trace metals. Our results indicate that all the cell lines displayed the same pattern of relative intracellular abundance of trace metals (Cu相似文献   

Expression pattern of DMAP-85 during Drosophila embryonic development

Microtubule-associated proteins (MAPs) play major regulatory roles on the organization and integrity of the cytoskeletal network. Previously, we identified DMAP-85, a Drosophila MAP that promotes tubulin polymerization in vitro. In this work, we examine the distribution of DMAP-85 and its association pattern with microtubules at embryonic stages. Immunoblots revealed that DMAP-85 was present throughout embryogenesis, but it was most abundant in stages 6-9. Immunofluorescence studies showed that DMAP-85 was associated with sub-populations of stable microtubules during embryo cellularization, and after gastrulation with interphase microtubule arrays. At late embryonic stages, it was preferentially found in the ventral nerve cord, co-localizing with axonal microtubules. These observations are in agreement with previous reports on DMAP-85 functions, suggesting that DMAP-85 might be required for the stabilization and organization of cytoplasmic microtubules during embryonic development.     

Proteoglycan production in Drosophila egg development: effect of beta-D-xyloside on proteoglycan synthesis and larvae motility

1. Proteoglycans (PGs) of the extracellular matrix (ECM) play an important role in several morphogenetic and differentiation events that occur during embryonic development. 2. The purpose of this work was to characterize the ECM PGs present during development of Drosophila melanogaster, in an attempt to elucidate their functional relevance. 3. The major 35SO4 incorporation into PGs occurred during the first instar larvae. Sulfated PGs (90%) from both first and second instar larvae were degraded by HNO2 treatment. 4. This result indicated that heparan sulfate proteoglycans (HSPG) are present in Drosophila ECM throughout early development. 5. Charge fractionation of PGs on DEAE-Sephacel columns indicated that most of them eluted at 0.45 M NaCl and were sensitive to HNO2. 6. The administration of beta-D-xyloside, a drug that competes with core proteins for the glycosaminoglycan synthetic apparatus, generated biochemical modifications in the ECM PGs together with alterations in larval locomotor behavior.     

Microbiome analysis and bacterial isolation from Lejía Lake soil in Atacama Desert

Extremophiles - As a consequence of the severe climatic change affecting our entire world, many lakes in the Andes Cordillera are likely to disappear within a few decades. One of these lakes is...     

Cytoskeletal organization of human mesenchymal stem cells (MSC) changes during their osteogenic differentiation

Human MSCs have been studied to define the mechanisms involved in normal bone remodeling and the regulation of osteogenesis. During osteogenic differentiation, MSCs change from their characteristic fibroblast-like phenotype to near spherical shape. In this study, we analyzed the correlation between the organization of cytoskeleton of MSCs, changes in cell morphology, and the expression of specific markers (alkaline phosphatase activity and calcium deposition) of osteogenic differentiation. For osteoblastic differentiation, cells were cultured in a culture medium supplemented with 100 nM dexamethasone, 10 mM beta- glycerophosphate, and 50 microg/ml ascorbic acid. The organization of microfilaments and microtubules was examined by inmunofluorescence using Alexa fluor 594 phalloidin and anti alpha-tubulin monoclonal antibody. Cytochalasin D and nocodazole were used to alter reversibly the cytoskeleton dynamic. A remarkable change in cytoskeleton organization was observed in human MSCs during osteogenic differentiation. Actin cytoskeleton changed from a large number of thin, parallel microfilament bundles extending across the entire cytoplasm in undifferentiated MSCs to a few thick actin filament bundles located at the outermost periphery in differentiated cells. Under osteogenic culture conditions, a reversible reorganization of microfilaments induced by an initial treatment with cytochalasin D but not with nocodazole reduced the expression of differentiation markers, without affecting the final morphology of the cells. The results indicate that changes in the assembly and disassembly kinetics of microfilaments dynamic of actin network formation may be critical in supporting the osteogenic differentiation of human MSCs; also indicated that the organization of microtubules appears to have a regulatory role on the kinetic of this process.