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  • Protein kinase C epsilon activates lens mitochondrial cytochrome c oxidase subunit IV during hypoxia. 18070622

    Protein kinase C (PKC) isoforms have been identified as major cellular signaling proteins that act directly in response to oxidation conditions. In retina and lens two isoforms of PKC respond to changes in oxidative stress, PKCgamma and PKCepsilon, while only PKCepsilon is found in heart. In heart the PKCepsilon acts on connexin 43 to protect from hypoxia. The presence of both isoforms in the lens led to this study to determine if lens PKCepsilon had unique targets. Both lens epithelial cells in culture and whole mouse lens were examined using PKC isoform-specific enzyme activity assays, co-immunoprecipitation, confocal microscopy, immunoblots, and light and electron microscopy. PKCepsilon was found in lens epithelium and cortex but not in the nucleus of mouse lens. The PKCepsilon isoform was activated in both epithelium and whole lens by 5% oxygen when compared to activity at 21% oxygen. In hypoxic conditions (5% oxygen) the PKCepsilon co-immunoprecipitated with the mitochondrial cytochrome c oxidase IV subunit (CytCOx). Concomitant with this the CytCOx enzyme activity was elevated and increased co-localization of CytCOx with PCKvarepsilon was observed using immunolabeling and confocal microscopy. In contrast, no hypoxia-induced activation of CytCOx was observed in lenses from the PKCepsilon knockout mice. Lens from 6-week-old PKCepsilon knockout mice had a disorganized bow region which was filled with vacuoles indicating a possible loss of mitochondria but the size of the lens was not altered. Electron microscopy demonstrated that the nuclei of the PCKepsilon knockout mice were abnormal in shape. Thus, PKCepsilon is found to be activated by hypoxia and this results in the activation of the mitochondrial protein CytCOx. This could protect the lens from mitochondrial damage under the naturally hypoxic conditions observed in this tissue. Lens oxygen levels must remain low. Elevation of oxygen which occurs during vitreal detachment or liquification is associated with cataracts. We hypothesize that elevated oxygen could cause inhibition of PKCepsilon resulting in a loss of mitochondrial protection.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-991
    Nombre del producto:
    Anti-PKCε Antibody

  • Regulation of protein S-thiolation by glutaredoxin 5 in the yeast Saccharomyces cerevisiae. 11882660

    The irreversible oxidation of cysteine residues can be prevented by protein S-thiolation, a process by which protein -SH groups form mixed disulfides with low molecular weight thiols such as glutathione. We report here that this protein modification is not a simple response to the cellular redox state, since different oxidants lead to different patterns of protein S-thiolation. SDS-polyacrylamide gel electrophoresis shows that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is the major target for modification following treatment with hydroperoxides (hydrogen peroxide or tert-butylhydroperoxide), whereas this enzyme is unaffected following cellular exposure to the thiol oxidant diamide. Further evidence that protein S-thiolation is tightly regulated in response to oxidative stress is provided by the finding that the Tdh3 GAPDH isoenzyme, and not the Tdh2 isoenzyme, is S-thiolated following exposure to H(2)O(2) in vivo, whereas both GAPDH isoenzymes are S-thiolated when H(2)O(2) is added to cell-free extracts. This indicates that cellular factors are likely to be responsible for the difference in GAPDH S-thiolation observed in vivo rather than intrinsic structural differences between the GAPDH isoenzymes. To begin to search for factors that can regulate the S-thiolation process, we investigated the role of the glutaredoxin family of oxidoreductases. We provide the first evidence that protein dethiolation in vivo is regulated by a monothiol-glutaredoxin rather than the classical glutaredoxins, which contain two active site cysteine residues. In particular, glutaredoxin 5 is required for efficient dethiolation of the Tdh3 GAPDH isoenzyme.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB374
    Nombre del producto:
    Anti-Glyceraldehyde-3-Phosphate Dehydrogenase Antibody, clone 6C5

  • Cytoskeletal and cell adhesion defects in wounded and Pax6+/- corneal epithelia. 19933176

    PAX6 heterozygosity (PAX6(+/-)) causes aniridia and aniridia-related keratopathy (ARK) in humans, but the pathway from gene dosage deficiency to clinical disease has not been fully characterized. Recently, the authors suggested a model of a chronic wound state exacerbated by oxidative stress, showed the barrier function of Pax6(+/-) corneas is compromised and suggested Pax6(+/-) corneas show the molecular signature of a perpetual wound-healing state.
    Tipo de documento:
    Referencia
    Referencia del producto:
    S7150
    Nombre del producto:
    OxyBlot Protein Oxidation Detection Kit

  • Alpha2-AMPK activity is not essential for an increase in fatty acid oxidation during low-intensity exercise. 18940938

    A single bout of exercise increases glucose uptake and fatty acid oxidation in skeletal muscle, with a corresponding activation of AMP-activated protein kinase (AMPK). While the exercise-induced increase in glucose uptake is partly due to activation of AMPK, it is unclear whether the increase of fatty acid oxidation is dependent on activation of AMPK. To examine this, transgenic mice were produced expressing a dominant-negative (DN) mutant of alpha(1)-AMPK (alpha(1)-AMPK-DN) in skeletal muscle and subjected to treadmill running. alpha(1)-AMPK-DN mice exhibited a 50% reduction in alpha(1)-AMPK activity and almost complete loss of alpha(2)-AMPK activity in skeletal muscle compared with wild-type littermates (WT). The fasting-induced decrease in respiratory quotient (RQ) ratio and reduced body weight were similar in both groups. In contrast with WT mice, alpha(1)-AMPK-DN mice could not perform high-intensity (30 m/min) treadmill exercise, although their response to low-intensity (10 m/min) treadmill exercise was not compromised. Changes in oxygen consumption and the RQ ratio during sedentary and low-intensity exercise were not different between alpha(1)-AMPK-DN and WT. Importantly, at low-intensity exercise, increased fatty acid oxidation in response to exercise in soleus (type I, slow twitch muscle) or extensor digitorum longus muscle (type II, fast twitch muscle) was not impaired in alpha(1)-AMPK-DN mice, indicating that alpha(1)-AMPK-DN mice utilize fatty acid in the same manner as WT mice during low-intensity exercise. These findings suggest that an increased alpha(2)-AMPK activity is not essential for increased skeletal muscle fatty acid oxidation during endurance exercise.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • TIA1 oxidation inhibits stress granule assembly and sensitizes cells to stress-induced apoptosis. 26738979

    Cytoplasmic stress granules (SGs) are multimolecular aggregates of stalled translation pre-initiation complexes that prevent the accumulation of misfolded proteins, and that are formed in response to certain types of stress including ER stress. SG formation contributes to cell survival not only by suppressing translation but also by sequestering some apoptosis regulatory factors. Because cells can be exposed to various stresses simultaneously in vivo, the regulation of SG assembly under multiple stress conditions is important but unknown. Here we report that reactive oxygen species (ROS) such as H2O2 oxidize the SG-nucleating protein TIA1, thereby inhibiting SG assembly. Thus, when cells are confronted with a SG-inducing stress such as ER stress caused by protein misfolding, together with ROS-induced oxidative stress, they cannot form SGs, resulting in the promotion of apoptosis. We demonstrate that the suppression of SG formation by oxidative stress may underlie the neuronal cell death seen in neurodegenerative diseases.
    Tipo de documento:
    Referencia
    Referencia del producto:
    17-700
    Nombre del producto:
    Magna RIP™ RNA-Binding Protein Immunoprecipitation Kit

  • Recovered insulin response by 2 weeks of leptin administration in high-fat fed rats is associated with restored AS160 activation and decreased reactive lipid accumulation ... 21525176

    Leptin is an adipokine that increases fatty acid (FA) oxidation, decreases intramuscular lipid stores, and improves insulin response in skeletal muscle. In an attempt to elucidate the underlying mechanisms by which these metabolic changes occur, we administered leptin (Lep) or saline (Sal) by miniosmotic pumps to rats during the final 2 wk of a 6-wk low-fat (LF) or high-fat (HF) diet. Insulin-stimulated glucose transport was impaired by the HF diet (HF-Sal) but was restored with leptin administration (HF-Lep). This improvement was associated with restored phosphorylation of Akt and AS160 and decreased in reactive lipid species (ceramide, diacylglycerol), known inhibitors of the insulin-signaling cascade. Total muscle citrate synthase (CS) activity was increased by both leptin and HF diet, but was not additive. Leptin increased subsarcolemmal (SS) and intramyofibrillar (IMF) mitochondria CS activity. Total muscle, sarcolemmal, and mitochondrial (SS and IMF) FA transporter (FAT/CD36) protein content was significantly increased with the HF diet, but not altered by leptin. Therefore, the decrease in reactive lipid stores and subsequent improvement in insulin response, secondary to leptin administration in rats fed a HF diet was not due to a decrease in FA transport protein content or altered cellular distribution.
    Tipo de documento:
    Referencia
    Referencia del producto:
    07-741

  • Single-base resolution analysis of active DNA demethylation using methylase-assisted bisulfite sequencing. 25362244

    Active DNA demethylation in mammals involves TET-mediated iterative oxidation of 5-methylcytosine (5mC)/5-hydroxymethylcytosine (5hmC) and subsequent excision repair of highly oxidized cytosine bases 5-formylcytosine (5fC)/5-carboxylcytosine (5caC) by thymine DNA glycosylase (TDG). However, quantitative and high-resolution analysis of active DNA demethylation activity remains challenging. Here, we describe M.SssI methylase-assisted bisulfite sequencing (MAB-seq), a method that directly maps 5fC/5caC at single-base resolution. Genome-wide MAB-seq allows systematic identification of 5fC/5caC in Tdg-depleted embryonic stem cells, thereby generating a base-resolution map of active DNA demethylome. A comparison of 5fC/5caC and 5hmC distribution maps indicates that catalytic processivity of TET enzymes correlates with local chromatin accessibility. MAB-seq also reveals strong strand asymmetry of active demethylation within palindromic CpGs. Integrating MAB-seq with other base-resolution mapping methods enables quantitative measurement of cytosine modification states at key transitioning steps of the active DNA demethylation cascade and reveals a regulatory role of 5fC/5caC excision repair in this step-wise process.
    Tipo de documento:
    Referencia
    Referencia del producto:
    07-449
    Nombre del producto:
    Anti-trimethyl-Histone H3 (Lys27) Antibody

  • Role of skeletal muscle mitochondrial density on exercise-stimulated lipid oxidation. 21681225

    Reduced skeletal muscle mitochondrial density is proposed to lead to impaired muscle lipid oxidation and increased lipid accumulation in sedentary individuals. We assessed exercise-stimulated lipid oxidation by imposing a prolonged moderate-intensity exercise in men with variable skeletal muscle mitochondrial density as measured by citrate synthase (CS) activity. After a 2-day isoenergetic high-fat diet, lipid oxidation was measured before and during exercise (650 kcal at 50% VO(2)max) in 20 healthy men with either high (HI-CS = 24 ± 1; mean ± s.e.) or low (LO-CS = 17 ± 1 nmol/min/mg protein) muscle CS activity. Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Respiratory exchange data and blood samples were collected at rest and throughout the exercise. HI-CS subjects had higher VO(2)max (50 ± 1 vs. 44 ± 2 ml/kg fat free mass/min; P = 0.01), lower fasting respiratory quotient (RQ) (0.81 ± 0.01 vs. 0.85 ± 0.01; P = 0.04) and higher ex vivo muscle palmitate oxidation (866 ± 168 vs. 482 ± 78 nmol/h/mg muscle; P = 0.05) compared to LO-CS individuals. However, whole-body exercise-stimulated lipid oxidation (20 ± 2 g vs. 19 ± 1 g; P = 0.65) and plasma glucose, lactate, insulin, and catecholamine responses were similar between the two groups. In conclusion, in response to the same energy demand during a moderate prolonged exercise bout, reliance on lipid oxidation was similar in individuals with high and low skeletal muscle mitochondrial density. This data suggests that decreased muscle mitochondrial density may not necessarily impair reliance on lipid oxidation over the course of the day since it was normal under a high-lipid oxidative demand condition. Twenty-four-hour lipid oxidation and its relationship with mitochondrial density need to be assessed.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB1628
    Nombre del producto:
    Anti-Myosin Antibody, slow muscle, clone NOQ7.5.4D

  • Double strand breaks can initiate gene silencing and SIRT1-dependent onset of DNA methylation in an exogenous promoter CpG island. 18704159

    Chronic exposure to inducers of DNA base oxidation and single and double strand breaks contribute to tumorigenesis. In addition to the genetic changes caused by this DNA damage, such tumors often contain epigenetically silenced genes with aberrant promoter region CpG island DNA hypermethylation. We herein explore the relationships between such DNA damage and epigenetic gene silencing using an experimental model in which we induce a defined double strand break in an exogenous promoter construct of the E-cadherin CpG island, which is frequently aberrantly DNA hypermethylated in epithelial cancers. Following the onset of repair of the break, we observe recruitment to the site of damage of key proteins involved in establishing and maintaining transcriptional repression, namely SIRT1, EZH2, DNMT1, and DNMT3B, and the appearance of the silencing histone modifications, hypoacetyl H4K16, H3K9me2 and me3, and H3K27me3. Although in most cells selected after the break, DNA repair occurs faithfully with preservation of activity of the promoter, a small percentage of the plated cells demonstrate induction of heritable silencing. The chromatin around the break site in such a silent clone is enriched for most of the above silent chromatin proteins and histone marks, and the region harbors the appearance of increasing DNA methylation in the CpG island of the promoter. During the acute break, SIRT1 appears to be required for the transient recruitment of DNMT3B and subsequent methylation of the promoter in the silent clones. Taken together, our data suggest that normal repair of a DNA break can occasionally cause heritable silencing of a CpG island-containing promoter by recruitment of proteins involved in silencing. Furthermore, with contribution of the stress-related protein SIRT1, the break can lead to the onset of aberrant CpG island DNA methylation, which is frequently associated with tight gene silencing in cancer.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Relevance of protein nitration in brain injury: a key pathophysiological mechanism in neurodegenerative, autoimmune, or inflammatory CNS diseases and stroke. 14661102

    This review has focused on the evidence for the involvement of nitrative oxidation in certain neurodegenerative disorders (Parkinson's Disease, Alzheimer's Disease, Amyotrophic Lateral Sclerosis), stroke, and inflammatory and autoimmune disorders (with particular attention devoted to multiple sclerosis).The relationship between protein peroxidation and pathological changes observed in the above disorders has been reported. Whereas many of the findings are from studies with animal models and autoptic specimens from human patients, few data are available from cerebrospinal fluid and blood samples of the patients at different times and disease stages.The participation of nitrative oxidation to the direct and indirect injury of neurons and other cells of the brain (i.e., oligodendrocytes, for multiple sclerosis) is clear; less evident is their relevance for the development and progression of these disorders.Further studies should be aimed to establish the clinical and prognostic value of peroxidative markers for the CNS diseases considered. This is fundamental for the development of therapeutic interventions antagonizing nitric oxide-related species damage.
    Tipo de documento:
    Referencia
    Referencia del producto:
    16-226