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971.
Sonia Tejada M. Val T. Lobo Mercedes Garc��a-Villanueva Silvia Sacrist��n M. Isabel P��rez-Morgado Matilde Salinas M. Elena Mart��n 《The journal of histochemistry and cytochemistry》2009,57(5):503-512
Increased protein synthesis is regulated, in part, by two eukaryotic translation initiation factors (eIFs): eIF4E and eIF2α. One or both of these factors are often overexpressed in several types of cancer cells; however, no data are available at present regarding eIF4E and eIF2α levels in brain tumors. In this study, we analyzed the expression, subcellular localization and phosphorylation states of eIF4E and eIF2α in 64 brain tumors (26 meningiomas, 16 oligodendroglial tumors, and 22 astrocytomas) and investigated the correlation with the expression of MIB-1, p53, and cyclin D1 proteins as well. There are significant differences in the phosphorylated eIF4E levels between the tumors studied, being the highest in meningiomas and the lowest in the oligodendroglial tumors. Relative to subcellular localization, eIF4E is frequently found in the nucleus of the oligodendroglial tumors and rarely in the same compartment of the meningiomas, whereas eIF2α showed an inverse pattern. Finally, cyclin D1 levels directly correlate with the phosphorylation status of both factors. The different expression, phosphorylation, or/and subcellular distribution of eIF2α and eIF4E within the brain types of tumors studied could indicate that different pathways are activated for promoting cell cycle proliferation, for instance, leading to increased cyclin D1 expression. (J Histochem Cytochem 57:503–512, 2009) 相似文献
972.
Patrícia Neves Isabel Sousa Mathias Winterhalter Paula Gameiro 《The Journal of membrane biology》2009,227(3):133-140
The outer membrane porin OmpF is an important protein for the uptake of antibiotics through the outer membrane of gram-negative
bacteria; however, the possible binding sites involved in this uptake are still not recognized. Determination, at the molecular
level, of the possible sites of antibiotic interaction is very important, not only to understand their mechanism of action
but also to unravel bacterial resistance. Due to the intrinsic OmpF fluorescence, attributed mainly to its tryptophans (Trp214, Trp61), quenching experiments were used to assess the site(s) of interaction of some quinolone antibiotics. OmpF was reconstituted
in different organized structures, and the fluorescence quenching results, in the presence of two quenching agents, acrylamide
and iodide, certified that acrylamide quenches Trp61 and iodide Trp214. Similar data, obtained in presence of the quinolones, revealed distinct behaviors for these antibiotics, with nalidixic
acid interacting near Trp214 and moxifloxacin near Trp61. These studies, based on straightforward and quick procedures, show the existence of conformational changes in the protein
in order to adapt to the different organized structures and to interact with the quinolones. The extent of reorganization
of the protein in the presence of the different quinolones allowed an estimate on the sites of protein/quinolone interaction. 相似文献
973.
Belen Joglar Jannette Rodriguez-Pallares Ana Isabel Rodriguez-Perez Pablo Rey Maria Jose Guerra Jose Luis Labandeira-Garcia 《Journal of neurochemistry》2009,109(2):656-669
The neurotoxin MPTP reproduces most of the biochemical and pathological hallmarks of Parkinson's disease. In addition to reactive oxygen species (ROS) generated as a consequence of mitochondrial complex I inhibition, microglial NADPH-derived ROS play major roles in the toxicity of MPTP. However, the exact mechanism regulating this microglial response remains to be clarified. The peptide angiotensin II (AII), via type 1 receptors (AT1), is one of the most important inflammation and oxidative stress inducers, and produces ROS by activation of the NADPH-oxidase complex. Brain possesses a local angiotensin system, which modulates striatal dopamine (DA) release. However, it is not known if AII plays a major role in microglia-derived oxidative stress and DA degeneration. The present study indicates that in primary mesencephalic cultures, DA degeneration induced by the neurotoxin MPTP/MPP+ is amplified by AII and inhibited by AT1 receptor antagonists, and that protein kinase C, NADPH-complex activation and microglial activation are involved in this effect. In mice, AT1 receptor antagonists inhibited both DA degeneration and early microglial and NADPH activation. The brain angiotensin system may play a key role in the self-propelling mechanism of Parkinson's disease and constitutes an unexplored target for neuroprotection, as previously reported for vascular diseases. 相似文献
974.
Sabino Pacheco Isabel G��mez Ivan Arenas Gloria Saab-Rincon Claudia Rodr��guez-Almaz��n Sarjeet S. Gill Alejandra Bravo Mario Sober��n 《The Journal of biological chemistry》2009,284(47):32750-32757
Bacillus thuringiensis Cry toxins are used worldwide as insecticides in agriculture, in forestry, and in the control of disease transmission vectors. In the lepidopteran Manduca sexta, cadherin (Bt-R1) and aminopeptidase-N (APN) function as Cry1A toxin receptors. The interaction with Bt-R1 promotes cleavage of the amino-terminal end, including helix α-1 and formation of prepore oligomer that binds to APN, leading to membrane insertion and pore formation. Loops of domain II of Cry1Ab toxin are involved in receptor interaction. Here we show that Cry1Ab mutants located in domain II loop 3 are affected in binding to both receptors and toxicity against Manduca sexta larvae. Interaction with both receptors depends on the oligomeric state of the toxin. Monomers of loop 3 mutants were affected in binding to APN and to a cadherin fragment corresponding to cadherin repeat 12 but not with a fragment comprising cadherin repeats 7–12. In contrast, the oligomers of loop 3 mutants were affected in binding to both Bt-R1 fragments but not to APN. Toxicity assays showed that either monomeric or oligomeric structures of Cry1Ab loop 3 mutations were severely affected in insecticidal activity. These data suggest that loop 3 is differentially involved in the binding with both receptor molecules, depending on the oligomeric state of the toxin and also that possibly a “ping pong” binding mechanism with both receptors is involved in toxin action. 相似文献
975.
Treichel H Mazutti MA Maugeri Filho F Rodrigues MI 《Bioprocess and biosystems engineering》2009,32(4):425-433
The present work aimed to study the viability of the use of sugarcane molasses and corn steep liquor (CSL) in a sequential
inulinase production performing an up-stream pretreatment of these agroindustrial residues. A sequential strategy was used
applying three central composite rotatable designs (CCRDs) to optimise medium composition, followed by a down-stream step.
The medium containing 150 g L−1 molasses, 50 g L−1 CSL and 6 g L−1 yeast extract, yielded a maximum inulinase production of 1,294 ± 7 U mL−1, after 72 h of fermentation. A down-stream evaluation was carried out using an expanded bed of Streamline DAE resin (Pharmacia),
with and without the up-stream treatment. The results showed that the enzyme could not be recovered from the non-pretreated
medium, whereas a yield of 91% was obtained in the adsorption stage from the medium prepared with the up-stream treatment,
showing the viability of producing the enzyme inulinase from agroindustrial residues using the integrated process. 相似文献
976.
Konstantin Schneider Jens Olaf Krömer Christoph Wittmann Isabel Alves-Rodrigues Andreas Meyerhans Juana Diez Elmar Heinzle 《Microbial cell factories》2009,8(1):12-14
Background
The cellular proteins Pat1p, Lsm1p, and Dhh1p are required for the replication of some positive-strand viruses and therefore are potential targets for new antiviral drugs. To prioritize host targets for antiviral drug screening a comparative metabolome analysis in Saccharomyces cerevisiae reference strain BY4742 Matα his3Δ1 leu2Δ0 lys2Δ0 ura3Δ0 and deletion strains pat1Δ, lsm1Δ and dhh1Δ was performed. 相似文献977.
Raimon Sanmartí Eduard Graell Maria L Perez Guadalupe Ercilla Odette Vi?as Jose A Gómez-Puerta Jordi Gratacós Alejandro Balsa Maria J Gómara Marta Larrosa Juan D Ca?ete Isabel Haro 《Arthritis research & therapy》2009,11(5):R135
Introduction
Evidence suggests that citrullinated fibrin(ogen) may be a potential in vivo target of anticitrullinated protein/peptide antibodies (ACPA) in rheumatoid arthritis (RA). We compared the diagnostic yield of three enzyme-linked immunosorbent assay (ELISA) tests by using chimeric fibrin/filaggrin citrullinated synthetic peptides (CFFCP1, CFFCP2, CFFCP3) with a commercial CCP2-based test in RA and analyzed their prognostic values in early RA.Methods
Samples from 307 blood donors and patients with RA (322), psoriatic arthritis (133), systemic lupus erythematosus (119), and hepatitis C infection (84) were assayed by using CFFCP- and CCP2-based tests. Autoantibodies also were analyzed at baseline and during a 2-year follow-up in 98 early RA patients to determine their prognostic value.Results
With cutoffs giving 98% specificity for RA versus blood donors, the sensitivity was 72.1% for CFFCP1, 78.0% for CFFCP2, 71.4% for CFFCP3, and 73.9% for CCP2, with positive predictive values greater than 97% in all cases. CFFCP sensitivity in RA increased to 80.4% without losing specificity when positivity was considered as any positive anti-CFFCP status. Specificity of the three CFFCP tests versus other rheumatic populations was high (> 90%) and similar to those for the CCP2. In early RA, CFFCP1 best identified patients with a poor radiographic outcome. Radiographic progression was faster in the small subgroup of CCP2-negative and CFFCP1-positive patients than in those negative for both autoantibodies. CFFCP antibodies decreased after 1 year, but without any correlation with changes in disease activity.Conclusions
CFFCP-based assays are highly sensitive and specific for RA. Early RA patients with anti-CFFCP1 antibodies, including CCP2-negative patients, show greater radiographic progression. 相似文献978.
979.
Isabel A. Calvo Natalia Gabrielli Iván Iglesias-Baena Sarela García-Santamarina Kwang-Lae Hoe Dong Uk Kim Miriam Sansó Alice Zuin Pilar Pérez José Ayté Elena Hidalgo 《PloS one》2009,4(8)
Background
An excess of caffeine is cytotoxic to all eukaryotic cell types. We aim to study how cells become tolerant to a toxic dose of this drug, and the relationship between caffeine and oxidative stress pathways.Methodology/Principal Findings
We searched for Schizosaccharomyces pombe mutants with inhibited growth on caffeine-containing plates. We screened a collection of 2,700 haploid mutant cells, of which 98 were sensitive to caffeine. The genes mutated in these sensitive clones were involved in a number of cellular roles including the H2O2-induced Pap1 and Sty1 stress pathways, the integrity and calcineurin pathways, cell morphology and chromatin remodeling. We have investigated the role of the oxidative stress pathways in sensing and promoting survival to caffeine. The Pap1 and the Sty1 pathways are both required for normal tolerance to caffeine, but only the Sty1 pathway is activated by the drug. Cells lacking Pap1 are sensitive to caffeine due to the decreased expression of the efflux pump Hba2. Indeed, ?hba2 cells are sensitive to caffeine, and constitutive activation of the Pap1 pathway enhances resistance to caffeine in an Hba2-dependent manner.Conclusions/Significance
With our caffeine-sensitive, genome-wide screen of an S. pombe deletion collection, we have demonstrated the importance of some oxidative stress pathway components on wild-type tolerance to the drug. 相似文献980.
Teresa Almeida Isabel Alonso Sandra Martins Eliana Marisa Ramos Luísa Azevedo Kinji Ohno António Amorim Maria Luiza Saraiva-Pereira Laura Bannach Jardim Tohru Matsuura Jorge Sequeiros Isabel Silveira 《PloS one》2009,4(2)
Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant neurodegenerative disease characterized by cerebellar ataxia and seizures. The disease is caused by a large ATTCT repeat expansion in the ATXN10 gene. The first families reported with SCA10 were of Mexican origin, but the disease was soon after described in Brazilian families of mixed Portuguese and Amerindian ancestry. The origin of the SCA10 expansion and a possible founder effect that would account for its geographical distribution have been the source of speculation over the last years. To unravel the mutational origin and spread of the SCA10 expansion, we performed an extensive haplotype study, using closely linked STR markers and intragenic SNPs, in families from Brazil and Mexico. Our results showed (1) a shared disease haplotype for all Brazilian and one of the Mexican families, and (2) closely-related haplotypes for the additional SCA10 Mexican families; (3) little or null genetic distance in small normal alleles of different repeat sizes, from the same SNP lineage, indicating that they are being originated by a single step mechanism; and (4) a shared haplotype for pure and interrupted expanded alleles, pointing to a gene conversion model for its generation. In conclusion, we show evidence for an ancestral common origin for SCA10 in Latin America, which might have arisen in an ancestral Amerindian population and later have been spread into the mixed populations of Mexico and Brazil. 相似文献