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  • Methionine sulfoxide reductase A (MsrA) protects cultured mouse embryonic stem cells from H2O2-mediated oxidative stress. 20506347

    Methionine sulfoxide reductase A (MsrA), a member of the Msr gene family, can reduce methionine sulfoxide residues in proteins formed by oxidation of methionine by reactive oxygen species (ROS). Msr is an important protein repair system which can also function to scavenge ROS. Our studies have confirmed the expression of MsrA in mouse embryonic stem cells (ESCs) in culture conditions. A cytosol-located and mitochondria-enriched expression pattern has been observed in these cells. To confirm the protective function of MsrA in ESCs against oxidative stress, a siRNA approach has been used to knockdown MsrA expression in ES cells which showed less resistance than control cells to hydrogen peroxide treatment. Overexpression of MsrA gene products in ES cells showed improved survivability of these cells to hydrogen peroxide treatment. Our results indicate that MsrA plays an important role in cellular defenses against oxidative stress in ESCs. Msr genes may provide a new target in stem cells to increase their survivability during the therapeutic applications.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Methionine sulfoxide reductase A and a dietary supplement S-methyl-L-cysteine prevent Parkinson's-like symptoms. 18032652

    Parkinson's disease (PD), a common neurodegenerative disease, is caused by loss of dopaminergic neurons in the substantia nigra. Although the underlying cause of the neuronal loss is unknown, oxidative stress is thought to play a major role in the pathogenesis of PD. The amino acid methionine is readily oxidized to methionine sulfoxide, and its reduction is catalyzed by a family of enzymes called methionine sulfoxide reductases (MSRs). The reversible oxidation-reduction cycle of methionine involving MSRs has been postulated to act as a catalytic antioxidant system protecting cells from oxidative damage. Here, we show that one member of the MSR family, MSRA, inhibits development of the locomotor and circadian rhythm defects caused by ectopic expression of human alpha-synuclein in the Drosophila nervous system. Furthermore, we demonstrate that one way to enhance the MSRA antioxidant system is dietary supplementation with S-methyl-L-cysteine (SMLC), found abundantly in garlic, cabbage, and turnips. SMLC, a substrate in the catalytic antioxidant system mediated by MSRA, prevents the alpha-synuclein-induced abnormalities. Therefore, interventions focusing on the enzymatic reduction of oxidized methionine catalyzed by MSRA represent a new prevention and therapeutic approach for PD and potentially for other neurodegenerative diseases involving oxidative stress.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB152
    Nombre del producto:
    Anti-Tyrosine Hydroxylase Antibody

  • Diverse effects of dimethyl sulfoxide (DMSO) on the differentiation potential of human embryonic stem cells. 22105179

    In vitro disease modeling using pluripotent stem cells can be a fast track screening tool for toxicological testing of candidate drug molecules. Dimethyl sulfoxide (DMSO) is one of the most commonly used solvents in drug screening. In the present investigation, we exposed 14- to 21-day-old embryoid bodies (EBs) to three different concentrations of DMSO [0.01% (low dose), 0.1% (medium dose) and 1.0% (high dose)] to identify the safest dose that could effectively be used as solvent. We found that DMSO treatment substantially altered the morphology and attachment of cells in concurrence with a significant reduction in cell viability in a dose-dependent manner. Gene expression studies revealed a selective downregulation of key markers associated with stemness (Oct-4, Sox-2, Nanog and Rex-1); ectoderm (Nestin, TuJ1, NEFH and Keratin-15); mesoderm (HAND-1, MEF-2C, GATA-4 and cardiac-actin); and endoderm (SOX-17, HNF-3β, GATA-6 and albumin), indicating an aberrant and untimely differentiation trajectory. Furthermore, immunocytochemistry, flow cytometry and histological analyses demonstrated substantial decrease in the levels of albumin and CK-18 proteins coupled with a massive reduction in the number of cells positive for PAS staining, implicating reduced deposits of glycogen. Our study advocates for the first time that DMSO exposure not only affects the phenotypic characteristics but also induces significant alteration in gene expression, protein content and functionality of the differentiated hepatic cells. Overall, our experiments warrant that hESC-based assays can provide timely alerts about the outcome of widespread applications of DMSO as drug solvent, cryoprotectant and differentiating agent.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB1637
    Nombre del producto:
    Anti-Tubulin Antibody, beta III isoform, CT, clone TU-20 (Similar to TUJ1)

  • A sensitive and specific ELISA detects methionine sulfoxide-containing apolipoprotein A-I in HDL. 18832772

    Oxidized HDL has been proposed to play a key role in atherogenesis. A wide range of reactive intermediates oxidizes methionine residues to methionine sulfoxide (MetO) in apolipoprotein A-I (apoA-I), the major HDL protein. These reactive species include those produced by myeloperoxidase, an enzyme implicated in atherogenesis. The aim of the present study was to develop a sensitive and specific ELISA for detecting MetO residues in HDL. We therefore immunized mice with HPLC-purified human apoA-I containing MetO(86) and MetO(112) (termed apoA-I(+32)) to generate a monoclonal antibody termed MOA-I. An ELISA using MOA-I detected lipid-free apoA-I(+32), apoA-I modified by 2e-oxidants (hydrogen peroxide, hypochlorous acid, peroxynitrite), and HDL oxidized by 1e- or 2e-oxidants and present in buffer or human plasma. Detection was concentration dependent, reproducible, and exhibited a linear response over a physiologically plausible range of concentrations of oxidized HDL. In contrast, MOA-I failed to recognize native apoA-I, native apoA-II, apoA-I modified by hydroxyl radical or metal ions, or LDL and methionine-containing proteins other than apoA-I modified by 2e-oxidants. Because the ELISA we have developed specifically detects apoA-I containing MetO in HDL and plasma, it should provide a useful tool for investigating the relationship between oxidized HDL and coronary artery disease.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo

  • Identification of a truncated form of Methionine Sulfoxide Reductase A expressed in mouse embryonic stem cells. 21696616

    Methionine Sulfoxide Reductase A (MsrA), an enzyme in the Msr gene family, is important in the cellular anti-oxidative stress defense mechanism. It acts by reducing the oxidized methionine sulfoxide in proteins back to sulfide and by reducing the cellular level of reactive oxygen species. MsrA, the only enzyme in the Msr gene family that can reduce the S-form epimers of methionine sulfoxide, has been located in different cellular compartments including mitochondria, cytosol and nuclei of various cell lines.In the present study, we have isolated a truncated form of the MsrA transcript from cultured mouse embryonic stem cells and performed eGFP fusion protein expression, confocal microscopy and real time RT-PCR studies.Results show a different expression response of this truncated transcript to oxygen deprivation and reoxygenation treatments in stem cells, compared to the longer full length form. In addition, a different subcellular localization pattern was noted with most of the eGFP fusion protein detected in the cytosol.One possibility for the existence of a truncated form of the MsrA transcripts could be that with a smaller protein size, yet retaining a GCWFG action site, this protein might have easier access to oxidize methionine residues on proteins than the longer form of the MsrA protein, thus having an evolutionary selection advantage. This research opens the door for further study on the role and function of the truncated MsrA embryonic mouse stem cells.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Relieving autophagy and 4EBP1 from rapamycin resistance. 21576371

    The mammalian target of rapamycin complex 1 (mTORC1) is a multiprotein signaling complex regulated by oncogenes and tumor suppressors. Outputs downstream of mTORC1 include ribosomal protein S6 kinase 1 (S6K1), eukaryotic translation initiation factor 4E (eIF4E), and autophagy, and their modulation leads to changes in cell growth, proliferation, and metabolism. Rapamycin, an allosteric mTORC1 inhibitor, does not antagonize equally these outputs, but the reason for this is unknown. Here, we show that the ability of rapamycin to activate autophagy in different cell lines correlates with mTORC1 stability. Rapamycin exposure destabilizes mTORC1, but in cell lines where autophagy is drug insensitive, higher levels of mTOR-bound raptor are detected than in cells where rapamycin stimulates autophagy. Using small interfering RNA (siRNA), we find that knockdown of raptor relieves autophagy and the eIF4E effector pathway from rapamycin resistance. Importantly, nonefficacious concentrations of an ATP-competitive mTOR inhibitor can be combined with rapamycin to synergistically inhibit mTORC1 and activate autophagy but leave mTORC2 signaling intact. These data suggest that partial inhibition of mTORC1 by rapamycin can be overcome using combination strategies and offer a therapeutic avenue to achieve complete and selective inhibition of mTORC1.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AP307P
    Nombre del producto:
    Goat Anti-Rabbit IgG Antibody, (H+L) HRP conjugate

  • Chemoprevention and inhibition of P-glycoprotein in cancer cells by Chinese medicinal herbs. 18690658

    Many of the herbal extracts used in the Chinese clinical medical routine inhibit the growth of tumor cells. In the present work, extracts of 12 selected herbs were prepared with methanol, chloroform, ethyl acetate and water, and the effects of these on the multidrug resistance (MDR) and P-glycoprotein of mouse lymphoma cells transfected with the human mdr1 gene and on a human lung alveolar epithelial cell line were investigated. The extracts were tested for antiproliferative effects, and the reversal of MDR in mouse lymphoma cells. The possible chemopreventive effect of the chloroform extracts was studied on the expression of cytomegalovirus (CMV) immediate-early (IE) antigen in human lung cancer cells (A549). The antimicrobial effects of the extracts were tested on some representative micro-organisms. Certain of the chloroform extracts of the plant materials were the most effective compounds on the reversal of MDR. Two of the chloroform extracts enhanced the antiproliferative effect of doxorubicin on MDR mouse lymphoma cells. The selected extracts did not show any antibacterial effect with the agar diffusion method. Certain chloroform extracts decreased the intermediate IE antigen expression of CMV in A459 cells. Copyright (c) 2008 John Wiley Sons, Ltd.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB810

  • Recombinant tissue plasminogen activator induces blood-brain barrier breakdown by a matrix metalloproteinase-9-independent pathway after transient focal cerebral ischemia ... 21895804

    The role of the inducible matrix metalloproteinase (MMP)-9 in blood-brain barrier (BBB) disruption after ischemic stroke is well accepted. Recombinant tissue plasminogen activator (r-tPA) is the only approved thrombolytic treatment of ischemic stroke but r-tPA is potentially neurotoxic. Vasogenic edema after r-tPA treatment has been linked with an increase in cerebral MMP-9. However, because cerebral ischemia clearly increases the levels of endogenous tPA, the consequence of additional r-tPA may be questionable. In this study, wild type and MMP-9 knockout mice were subjected to 90 min transient middle cerebral artery occlusion and treated with 10 mg/kg r-tPA. At 24 h after occlusion, BBB permeability, hemispheric enlargement, collagen and laminin degradation as well as cerebral infarction were increased in both wild type and MMP-9 knockout treated animals as compared with non-treated animals. Mortality was increased in wild type but reduced in knockout treated mice. Cerebral MMP-9 concentration was not modified by r-tPA. However, pre-treatment with p-aminobenzoyl-gly-pro-D-leu-D-ala-hydroxamate, a broad-spectrum MMP inhibitor, counteracted the effects of r-tPA on the neurovascular unit and decreased mortality in both wild type and knockout mice. MMP inhibition did not modify cerebral infarction in r-tPA-treated animals. Our results suggest that r-tPA toxicity is mainly independent of MMP-9 after transient middle cerebral artery occlusion but could involve some other MMPs. Additionally, our results support the hypothesis of a dissociation between r-tPA-dependent mechanisms of BBB breakdown and cerebral infarction. Due to the importance of r-tPA in thrombolytic treatment of ischemic stroke patients, the MMPs that could participate in r-tPA-induced BBB disruption should be further characterized.
    Tipo de documento:
    Referencia
    Referencia del producto:
    CC079