Supplemental Ascorbate Diminishes DNA Damage Yet Depletes Glutathione and Increases Acute Liver Failure in a Mouse Model of Hepatic Antioxidant System Disruption

Cellular oxidants are primarily managed by the thioredoxin reductase-1 (TrxR1)- and glutathione reductase (Gsr)-driven antioxidant systems. In mice having hepatocyte-specific codisruption of TrxR1 and Gsr (TrxR1/Gsr-null livers), methionine catabolism sustains hepatic levels of reduced glutathione (GSH). Although most mice with TrxR1/Gsr-null livers exhibit long-term survival, ~25% die from spontaneous liver failure between 4- and 7-weeks of age. Here we tested whether liver failure was ameliorated by ascorbate supplementation. Following ascorbate, dehydroascorbate, or mock treatment, we assessed survival, liver histology, or hepatic redox markers including GSH and GSSG, redox enzyme activities, and oxidative damage markers. Unexpectedly, rather than providing protection, ascorbate (5 mg/mL, drinking water) increased the death-rate to 43%. In adults, ascorbate (4 mg/g × 3 days i.p.) caused hepatocyte necrosis and loss of hepatic GSH in TrxR1/Gsr-null livers but not in wildtype controls. Dehydroascorbate (0.3 mg/g i.p.) also depleted hepatic GSH in TrxR1/Gsr-null livers, whereas GSH levels were not significantly affected by either treatment in wildtype livers. Curiously, however, despite depleting GSH, ascorbate treatment diminished basal DNA damage and oxidative stress markers in TrxR1/Gsr-null livers. This suggests that, although ascorbate supplementation can prevent oxidative damage, it also can deplete GSH and compromise already stressed livers

ERP Conceptual Ecology

The technological evolution of recent years has made that information systems frequently adapt to the market realities to fulfill the improvements of the company’s organizational processes. In this context, new paradigms, approaches, and concepts were disseminated through the new realities of information systems. This study aims to verify how ERP (Enterprise Resource Planning) has been related to other information systems within its ecosystem. For this purpose, we have reviewed the literature based on 650 publications whose central theme was the ERP. The data were treated through a graphical analysis, inspired by SNA (Social Network Analysis), represented by related ERP concepts. The study results, determine the connection degree between the concepts that emerged with the technological evolution and the ERP, thus representing the ERP interoperability tendencies, over the last years. The study concludes that ERPs have been improving and substantially increasing the conditions of nteroperability with other information systems and with new organizational concepts that have emerged through the technological availability. This fact led to a better organizational process’s adoption and more organizational performance.info:eu-repo/semantics/publishedVersio

Obesity-Related Upregulation of Monocyte Chemotactic Factors in Adipocytes : Involvement of Nuclear Factor-κB and c-Jun NH2-Terminal Kinase Pathways

OBJECTIVE—We sought to evaluate the entire picture of all monocyte chemotactic factors that potentially contribute to adipose tissue macrophage accumulation in obesity

Regulation of PTP1D mRNA by Peptide Growth Factors in the Human Endometrial Cell Line HEC-1-A

Objective: To assess, in the human endometrial cell line HEC-1-A, the presence of protein tyrosine phosphatase 1D (PTDP1D) and the possible regulation of its mRNA expression by mitogens such as forskolin (an agent that increases intracellular cyclic adenosine monophosphate [cAMP] levels), epidermal growth factor (EGF), and insulin-like growth factor-I (IGF-I). Methods: Cells were grown to confluence and maintained in serum-free media for 24 hours before treatment. Cells were exposed to forskolin, EGF, and IGF-I for increasing time periods (0, 1, 3, 6, and 24 hours), and PTP1D mRNA expression was determined by Northern blot analysis. In addition, cells were incubated with increasing doses of forskolin (final concentrations: 1, 5, 10, 20, and 30 μmol/L0 for 6 hours. Results: When treated with the various mitogens, cells increased their stimulation of PTP1D mRNA expression in a time- and dose-dependent fashion. Specifically, forskolin, EGF, and IGF-I induced maximal mRNA expression at 6, 3, and 6 hours, respectively. Expression induced by forskolin, EGF, and IGF-I was five, three, and six times control levels, respectively. At a dose of 10 μmol/L, forskolin induced PTP1D mRNA expression almost two times higher than control values. Conclusion: These data suggest that in human endometrial carcinomas, cAMP, EGF, and IGF-I may regulate the expression of PTP1D mRNA, which may, in turn, play a role in uncontrolled cell proliferation and neoplastic transformation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68928/2/10.1177_107155769700400608.pd

The crystal structure of the Sgt1-Skp1 complex: the link between Hsp90 and both SCF E3 ubiquitin ligases and kinetochores

The essential cochaperone Sgt1 recruits Hsp90 chaperone activity to a range of cellular factors including SCF E3 ubiquitin ligases and the kinetochore in eukaryotes. In these pathways Sgt1 interacts with Skp1, a small protein that heterodimerizes with proteins containing the F-box motif. We have determined the crystal structure of the interacting domains of Saccharomyces cerevisiae Sgt1 and Skp1 at 2.8 Å resolution and validated the interface in the context of the full-length proteins in solution. The BTB/POZ domain of Skp1 associates with Sgt1 via the concave surface of its TPR domain using residues that are conserved in humans. Dimerization of yeast Sgt1 occurs via an insertion that is absent from monomeric human Sgt1. We identify point mutations that disrupt dimerization and Skp1 binding in vitro and find that the interaction with Skp1 is an essential function of Sgt1 in yeast. Our data provide a structural rationale for understanding the phenotypes of temperature-sensitive Sgt1 mutants and for linking Skp1-associated proteins to Hsp90-dependent pathways

A Generic Platform for Cellular Screening Against Ubiquitin Ligases

Ubiquitin signalling regulates most aspects of cellular life, thus deregulation of ubiquitylation has been linked with a number of diseases. E3 ubiquitin ligases provide substrate selectivity in ubiquitylation cascades and are therefore considered to be attractive targets for developing therapeutic molecules. In contrast to established drug target classes, such as protein kinases, GPCRs, hormone receptors and ion channels, ubiquitin drug discovery is in its early stages. This is, in part, due to the complexity of the ubiquitylation pathways and the lack of robust quantitative technologies that allow high-throughput screening of inhibitors. Here we report the development of a Ubiquitin Ligase Profiling system, which is a novel and generic cellular technology designed to facilitate identification of selective inhibitors against RING type E3 ubiquitin ligases. Utilization of this system requires a single co-transfection of cells with assay vectors, thereby enabling readout of E3 ubiquitin ligase catalytic activity within the cellular environment. Therefore, our robust high-throughput screening platform offers novel opportunities for the development of inhibitors against this difficult-to-target E3 ligase enzyme class

The fission yeast Rpb4 subunit of RNA polymerase II plays a specialized role in cell separation

RNA polymerase II is a complex of 12 subunits, Rpb1 to Rpb12, whose specific roles are only partly understood. Rpb4 is essential in mammals and fission yeast, but not in budding yeast. To learn more about the roles of Rpb4, we expressed the rpb4 gene under the control of regulatable promoters of different strength in fission yeast. We demonstrate that below a critical level of transcription, Rpb4 affects cellular growth proportional to its expression levels: cells expressing lower levels of rpb4 grew slower compared to cells expressing higher levels. Lowered rpb4 expression did not affect cell survival under several stress conditions, but it caused specific defects in cell separation similar to sep mutants. Microarray analysis revealed that lowered rpb4 expression causes a global reduction in gene expression, but the transcript levels of a distinct subset of genes were particularly responsive to changes in rpb4 expression. These genes show some overlap with those regulated by the Sep1-Ace2 transcriptional cascade required for cell separation. Most notably, the gene expression signature of cells with lowered rpb4 expression was highly similar to those of mcs6, pmh1, sep10 and sep15 mutants. Mcs6 and Pmh1 encode orthologs of metazoan TFIIH-associated cyclin-dependent kinase (CDK)-activating kinase (Cdk7-cyclin H-Mat1), while Sep10 and Sep15 encode mediator components. Our results suggest that Rpb4, along with some other general transcription factors, plays a specialized role in a transcriptional pathway that controls the cell cycle-regulated transcription of a specific subset of genes involved in cell division. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00438-006-0161-5 and is accessible for authorized users