M. Torres-márquez - Academia.edu (original) (raw)

Papers by M. Torres-márquez

Archives of Microbiology, 2008

Living organisms are subject to stress, and among these stressors, heavy metals exposure triggers... more Living organisms are subject to stress, and among these stressors, heavy metals exposure triggers accumulation of sulfur metabolites. Among these metabolites, glutathione and phytochelatins are found in several organisms, such as Euglena gracilis. Pre-exposing E. gracilis to low concentrations of Hg2+ generates a population with resistance to even 0.2 mM Cd2+, and this resistance relies partly on phytochelatins. p38 MAPK is stimulated by stress and is involved in apoptotic as well as survival mechanisms. In this study, we explored its participation in heavy metal-induced stress and its possible role in sulfur metabolite accumulation. We found that about 51% of the E. gracilis pretreated with Hg2+ becomes resistant to Cd2+ and proliferates despite the presence of this metal. The accumulation of the sulfur metabolites gamma-glu-cys, glutathione and phytochelatin 2 displayed cyclic patterns that were disturbed by a challenge with Cd2+. We observed a p38 MAPK-like activity that was stimulated by acute or chronic heavy metal exposure, and its inhibition by SB203580 slightly diminished the accumulation of sulfur compounds. p38 MAPK inhibition also affected basal levels of glutathione in either pretreated or control cells. Thus, it appears that p38 MAPK mediates redox stress component of the signal pathway induced by heavy metals.

Journal of Biological Chemistry, 1994

The FASEB Journal, 2014

PKD is a founding member of CAMK group of kinases and there is ample evidence of its participatio... more PKD is a founding member of CAMK group of kinases and there is ample evidence of its participation in important cellular process including stress. Due to the lack of specific inhibitors for its action in vivo, its protein targets are scarcely described. Even less is known about its role at regulating the transcription of target proteins. The miRNA are important regulators of protein expression and several groups are currently undertaking studies about its targets, enriching a database that will enable a better understanding of the networks in which they participate. In this work we aimed to identify miRNA that are modulated by hyperosmotic stress in 3T3 expressing PKD-1 cells as a means to understand the PKD participation in this cellular process. We obtained the RNA from 3T3-PKD-1 cells and their control counterparts, without or with an hour challenge with 0.3M NaCl, and sought to identify the up- or down- regulated miRNA. This was performed using miRNA3.0 Affymetrix microchips, and analyzed with softwar...

Neurochemistry International, 2001

The role of phosphorylation events on the activation and modulation of the osmosensitive 3 H-taur... more The role of phosphorylation events on the activation and modulation of the osmosensitive 3 H-taurine release (OTR) was examined in cultured cerebellar granule neurons (CGN) stimulated with 30% hyposmotic solutions. OTR was not decreased when [Ca 2+ ] i rise evoked by hyposmolarity was prevented by EGTA-AM (50 mM) or depleted by treatment with 1 mM ionomycin in Ca 2+-free medium. Accordingly, OTR was not inhibited by Ca 2+-dependent signaling events. The calmodulin (CAM) blocker W-7 (50 mM) potentiated OTR while the Ca 2+ /CAM kinase blocker KN-93 (10 mM) was without eect. Blockade of PKC by H-7, H-8 (50 mM) and GoÈ 6976 (1 mM), as well as activation by phorbol myristate acetate (PMA) (100 nM) did not in¯uence OTR, but chronic treatment to down regulate PKC decreased it by 30%. Forskolin (20 mM) and 8-BrcAMP (10 mM) did not change OTR. Protein tyrosine phosphorylation seems to be of crucial importance in the activation and modulation of OTR, as it was markedly inhibited (90%) by tyrphostine A23 (50 mM) and potentiated by the tyrosine phosphatase inhibitor ortho-vanadate (100 mM). The PI3 kinase blocker wortmannin 100 nM essentially abolished OTR but LY294002 (10±100 mM) was without eect. This dierence may be accounted for PI3K isoforms in neurons with dierent sensitivity to the blockers. Alternatively, the eect of wortmannin may be exerted not in PI3 kinase but instead on phospholipases, which are also sensitive to this blocker. The hyposmotic stimulus induced activation of Erk1/Erk2, but blockade of this eect by PD 98059 (50 mM) only marginally decreased OTR suggesting that the Erk1/Erk2 is an epiphenomenon, not directly involved in OTR activation.

The International Journal of Biochemistry & Cell Biology, 2010

It has been assumed that oxidative phosphorylation (OxPhos) in solid tumors is severely reduced d... more It has been assumed that oxidative phosphorylation (OxPhos) in solid tumors is severely reduced due to cytochrome c oxidase substrate restriction, although the measured extracellular oxygen concentration in hypoxic areas seems not limiting for this activity. To identify alternative hypoxia-induced OxPhos depressing mechanisms, an integral analysis of transcription, translation, enzyme activities and pathway fluxes was performed on glycolysis and OxPhos in HeLa and MCF-7 carcinomas. In both neoplasias exposed to hypoxia, an early transcriptional response was observed after 8h (two times increased glycolysis-related mRNA synthesis promoted by increased HIF-1alpha levels). However, major metabolic remodeling was observed only after 24h hypoxia: increased glycolytic protein content (1-5-times), enzyme activities (2-times) and fluxes (4-6-times). Interestingly, in MCF-7 cells, 24h hypoxia decreased OxPhos flux (4-6-fold), and 2-oxoglutarate dehydrogenase and glutaminase activities (3-fold), with no changes in respiratory complexes I and IV activities. In contrast, 24h hypoxia did not significantly affect HeLa OxPhos flux; neither mitochondria related mRNAs, protein contents or enzyme activities, although the enhanced glycolysis became the main ATP supplier. Thus, prolonged hypoxia (a) targeted some mitochondrial enzymes in MCF-7 but not in HeLa cells, and (b) induced a transition from mitochondrial towards a glycolytic-dependent energy metabolism in both MCF-7 and HeLa carcinomas.

Journal of Bioenergetics and Biomembranes, 1996

Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2000

Archives of Microbiology, 2005

To determine the onset of the Cd2+-hyperaccumulating phenotype in Euglena gracilis, induced by Hg... more To determine the onset of the Cd2+-hyperaccumulating phenotype in Euglena gracilis, induced by Hg2+ pretreatment (Avilés et al. in Arch Microbiol 180:1-10, 2003), the changes in cellular growth, Cd2+ uptake, and intracellular contents of sulfide, cysteine, gamma-glutamylcysteine, glutathione and phytochelatins during the progress of the culture were analyzed. In cells exposed to 0.2 mM CdCl2, the Cd2+-hyperaccumulating phenotype was apparent only after 48 h of culture, as indicated by the significant increase in cell growth and higher internal contents of sulfide and thiol-compounds, along with a higher gamma-glutamylcysteine synthetase activity. However, the stiochiometry of thiol-compounds/Cd2+ accumulated was similar for both control and Hg2+-pretreated cells. Moreover, the value for this ratio was 2.1 or lower after 48-h culture, which does not suffice to fully inactivate Cd2+. It is concluded that, although the glutathione and phytochelatin synthesis pathway is involved in the development of the Cd2+-hyperaccumulating phenotype in E. gracilis, apparently other pathways and sub-cellular mechanisms are also involved. These may be an increase in other Cd2+ chelating molecules such as di- and tricarboxylic acids, phosphate and polyphosphates, as well as Cd2+ compartmentation into organelles.

Archives of Biochemistry and Biophysics, 2000

The oxidation of several metabolites in AS-30D tumor cells was determined. Glucose and glycogen c... more The oxidation of several metabolites in AS-30D tumor cells was determined. Glucose and glycogen consumption and lactic acid production showed high rates, indicating a high glycolytic activity. The utilization of ketone bodies, oxidation of endogenous glutamate, and oxidative phosphorylation were also very active: tumor cells showed a high respiration rate (100 ng atoms oxygen (min ؋ 10 7 cells) ؊1), which was 90% oligomycin-sensitive. AS-30D tumor cells underwent significant intracellular volume changes, which preserved high concentrations of several metabolites. A high O 2 concentration, but a low glucose concentration were found in the cell-free ascites liquid. Glutamine was the oxidizable substrate found at the highest concentration in the ascites liquid. We estimated that cellular ATP was mainly provided by oxidative phosphorylation. These data indicated that AS-30D hepatoma cells had a predominantly oxidative and not a glycolytic type of metabolism. The NADH-ubiquinol oxido reductase and the enzyme block for ATP utilization were the sites that exerted most of the control of oxidative phosphorylation (flux control coefficient ‫؍‬ 0.3-0.42).

Archives of Biochemistry and Biophysics, 2001

The activity of the pyridine nucleotide-independent lactate dehydrogenase (iLDH) was characterize... more The activity of the pyridine nucleotide-independent lactate dehydrogenase (iLDH) was characterized in mitochondria isolated from the protist Euglena gracilis. The dissociation constants for Land D-lactate were similar, but the V max was higher with the D isomer. A ping-pong kinetic mechanism was displayed with 2,4dichlorophenol-indolphenol (DCPIP), or coenzyme Q 1 , reacting as the second substrate with the modified, reduced enzyme. Oxamate was a competitive inhibitor against both Land D-lactate. Oxalate exerted a mixedtype inhibition regarding L-or D-lactate and also against DCPIP. The rate of L-lactate uptake was partially inhibited by mersalyl and lower than the rate of dehydrogenation, which was mersalyl-insensitive. These data suggested that the active site of L-iLDH was orientated toward the intermembrane space. The following observations indicated the existence of two stereo-specific iLDH enzymes in the inner membrane of Euglena mitochondria: a greater affinity of the D-iLDH for both inhibitors, D-iLDH thermo-stability at 70°C and denaturation of L-iLDH, opposite signs in the enthalpy change for the association reaction of the isomers to the enzyme, differential solubilization of both activities with detergents, and different molecular mass.

Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology, 1997

The effect of different concentrations of Hg2+, Cd2+, and Pb2+ on ultrastructure, growth, respira... more The effect of different concentrations of Hg2+, Cd2+, and Pb2+ on ultrastructure, growth, respiration, photosynthesis, chlorophyll content, and metal accumulation in Euglena gracilis was examined. The toxicity of the heavy metals was dependent on the culture medium used and whether cells were grown in the dark or under illumination. Hg2+ was the most toxic metal, which showed effects at a concentration as low as 1.5 μM; Cd2+ showed an intermediate toxicity (effects observed above 50 μM); and Pb2+ was almost ineffective up to 1 mM. Cells grown for several weeks in the dark, in the presence of 1.5 μM Hg2+ showed a reduced sensitivity to subsequent exposure to Cd2+ or Pb2+. The Hg2+-pretreated cells also presented an enhanced capacity to accumulate other metals. In comparison, light-grown cells showed a greater Cd2+ accumulation, but a lower Pb2+ uptake than Hg2+-pretreated dark-grown cells. Pretreatment of light-grown cells with Hg2+ did not enhance the accumulation of Cd2+. These res...

La respuesta inflamatoria implica la generacion de citocinas en la que participa el factor de tra... more La respuesta inflamatoria implica la generacion de citocinas en la que participa el factor de transcripcion NFkB, este puede ser activado por la via de MAPK u otras vias que estimulan a la cinasa IKKb; la cinasa tambien es regulada por ubiquitinacion/ desubiquitinacion. Las bacterias para establecer la infeccion han desarrollado mecanismos de interferencia con ambas vias, con la ubiquitinacion al mimetizar las reacciones de las E3 ligasas y las desubiquitinasas del hospedero, de manera que evade selectivamente la degradacion de proteinas. Las toxinas bacterianas tambien interfieren con la via de las MAPK ya sea por desfosforilacion o modificacion de sus componentes para evitar su activacion. En esta revision nos abocamos a las toxinas bacterianas con accion sobre la ubiquitinacion/desubiquitinacion y la influencia que tienen en la supresion de la inflamacion por la interferencia con la cascada de las MAPK

Plasmid encoded protein (Pet), a product of E. coli, infiltrates leukocyte in experimental models... more Plasmid encoded protein (Pet), a product of E. coli, infiltrates leukocyte in experimental models and acts on macrophages as a chemokine. As an immune response orchestrator, macrophages play an important role in inducing proinflammatory cytokines. In this work, we tested whether in macrophages Pet stimulates the expression of IL1, TNF , MIF and the antagonist IL1Ra. We also sought the IKK /NF B pathway as a possible mediator. We found that indeed Pet increases the mRNA of inflammatory cytokines and the antagonist IL1Ra with different rates and kinetics through the IKK /NF B pathway, which could be consistent as a factor in chronic inflammation.

Proceedings of the Western Pharmacology Society, 1991

Molecular pharmacology, 1992

In isolated rat white adipocytes, epinephrine (in the presence of 10 microM propranolol) increase... more In isolated rat white adipocytes, epinephrine (in the presence of 10 microM propranolol) increased the uptake of [32P]Pi into phosphatidylinositol in a dose-dependent fashion. When the cells were pretreated with the irreversible antagonist chlorethylclonidine, this alpha 1-adrenergic effect was markedly diminished. The effect of epinephrine was dose-dependently antagonized by selective alpha 1-adrenergic antagonists, with the potency order prazosin greater than 5-methylurapidil greater than or equal to WB4101. Binding studies using crude membrane preparations were performed with the ligands [3H]bunazosin and 125I-HEAT. Both ligands bound to membrane sites with high affinity (Kd values of 0.75 +/- 0.20 nM for [3H]bunazosin and 125 +/- 20 pM for 125I-HEAT), in a rapid, reversible, and saturable (Bmax, 9-12 fmol/mg of protein) fashion, and with the expected pharmacological characteristics for alpha 1-adrenoceptors. Binding displacement studies with these ligands indicated a potency ord...