Incidence and potential implications of methylglyoxal in industrial cell culture revisited

Methylglyoxal is a toxic by-product of glycolysis and amino acid metabolism in mammalian systems. The major route for methylglyoxal detoxification is the glyoxalase pathway, which consists of the enzymes glyoxalase I (GLO1) and glyoxalase II (GLO2). A required co-factor for the glyoxalase pathway is reduced glutathione. Evidence suggests that GLOI and methylglyoxal have important roles to play in the signal pathways associated with oxidative stress and necrotic cell death1. Previous work has demonstrated that growth conditions found in industrial cell culture have marked effects on endogenous methylglyoxal levels in Chinese hamster ovary (CHO)2. Furthermore, decreased levels of methylglyoxal were associated with increased cell viability. More recently, this compound has been found to modify recombinant antibodies expressed in CHO at specific arginine residues3. Here, the implications of methylglyoxal are discussed in the context of past and current works relevant to industrial cell cultur

Invented Spelling and Reading Achievement

The purpose of this study was to determine if first graders, invented spelling and Marie Clay’s Concepts of Print test, used together and separately, are significant predictors of future reading achievement. The study also compared the prediction ability of an invented spelling stage to the prediction ability of the Concepts of Print test. The subjects of this study comprised 39 first graders from two classrooms in a rural Western New York school. During the month of September, invented spelling samples from the subjects’ journals were analyzed and categorized into stages. In addition, classroom teachers administered the Concepts of Print test to each subject. In May of the same year, the spring California Achievement Test was administered to each subject. A regression analysis and t test were used to evaluate how effective an invented spelling stage and Marie Clay\u27s Concepts of test, used together and separately, are in predicting future reading achievement. The findings of the study indicate that an invented spelling stage can predict, slightly better than Marie Clay’s Concepts of Print test, a first graders future reading achievement. Invented spelling used in conjunct ion with Marie Clay\u27s Concepts of Print test is a stronger predictor of reading achievement than using either tool separately

Invented Spelling and Reading Achievement

The purpose of this study was to determine if first graders, invented spelling and Marie Clay’s Concepts of Print test, used together and separately, are significant predictors of future reading achievement. The study also compared the prediction ability of an invented spelling stage to the prediction ability of the Concepts of Print test. The subjects of this study comprised 39 first graders from two classrooms in a rural Western New York school. During the month of September, invented spelling samples from the subjects’ journals were analyzed and categorized into stages. In addition, classroom teachers administered the Concepts of Print test to each subject. In May of the same year, the spring California Achievement Test was administered to each subject. A regression analysis and t test were used to evaluate how effective an invented spelling stage and Marie Clay's Concepts of test, used together and separately, are in predicting future reading achievement. The findings of the study indicate that an invented spelling stage can predict, slightly better than Marie Clay’s Concepts of Print test, a first graders future reading achievement. Invented spelling used in conjunct ion with Marie Clay's Concepts of Print test is a stronger predictor of reading achievement than using either tool separately.SUNY BrockportEducation and Human DevelopmentMaster of Science in Education (MSEd)Education and Human Development Master's These

A metabolite-derived protein modification integrates glycolysis with KEAP1-NRF2 signalling.

Mechanisms that integrate the metabolic state of a cell with regulatory pathways are necessary to maintain cellular homeostasis. Endogenous, intrinsically reactive metabolites can form functional, covalent modifications on proteins without the aid of enzymes1,2, and regulate cellular functions such as metabolism3-5 and transcription6. An important 'sensor' protein that captures specific metabolic information and transforms it into an appropriate response is KEAP1, which contains reactive cysteine residues that collectively act as an electrophile sensor tuned to respond to reactive species resulting from endogenous and xenobiotic molecules. Covalent modification of KEAP1 results in reduced ubiquitination and the accumulation of NRF27,8, which then initiates the transcription of cytoprotective genes at antioxidant-response element loci. Here we identify a small-molecule inhibitor of the glycolytic enzyme PGK1, and reveal a direct link between glycolysis and NRF2 signalling. Inhibition of PGK1 results in accumulation of the reactive metabolite methylglyoxal, which selectively modifies KEAP1 to form a methylimidazole crosslink between proximal cysteine and arginine residues (MICA). This posttranslational modification results in the dimerization of KEAP1, the accumulation of NRF2 and activation of the NRF2 transcriptional program. These results demonstrate the existence of direct inter-pathway communication between glycolysis and the KEAP1-NRF2 transcriptional axis, provide insight into the metabolic regulation of the cellular stress response, and suggest a therapeutic strategy for controlling the cytoprotective antioxidant response in several human diseases

Steady-State Growth under Inorganic Carbon Limitation Conditions Increases Energy Consumption for Maintenance and Enhances Nitrous Oxide Production in Nitrosomonas europaea

Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH₃) to obtain energy for growth on carbon dioxide (CO₂) and can also produce nitrous oxide (N₂O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon (IC) provided by either 1.0 mM or 0.2 mM sodium carbonate (Na₂CO₃) supplemented with atmospheric CO₂. IC-limited cultures oxidized 25 to 58% of available NH₃ to nitrite, depending on the dilution rate and Na₂CO₃ concentration. IC limitation resulted in a 2.3-fold increase in cellular maintenance energy requirements compared to those for NH₃-limited cultures. Rates of N₂O production increased 2.5- and 6.3-fold under the two IC-limited conditions, increasing the percentage of oxidized NH₃-N that was transformed to N₂O-N from 0.5% (replete) up to 4.4% (0.2 mM Na₂CO₃). Transcriptome analysis showed differential expression (P ≤ 0.05) of 488 genes (20% of inventory) between replete and IC-limited conditions, but few differences were detected between the two IC-limiting treatments. IC-limited conditions resulted in a decreased expression of ammonium/ammonia transporter and ammonia monooxygenase subunits and increased the expression of genes involved in C₁ metabolism, including the genes for RuBisCO (cbb gene cluster), carbonic anhydrase, folate-linked metabolism of C₁ moieties, and putative C salvage due to oxygenase activity of RuBisCO. Increased expression of nitrite reductase (gene cluster NE0924 to NE0927) correlated with increased production of N₂O. Together, these data suggest that N. europaea adapts physiologically during IC-limited steady-state growth, which leads to the uncoupling of NH₃ oxidation from growth and increased N₂O production. IMPORTANCE: Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, is an important process in the global nitrogen cycle. This process is generally dependent on ammonia-oxidizing microorganisms and nitrite-oxidizing bacteria. Most nitrifiers are chemolithoautotrophs that fix inorganic carbon (CO₂) for growth. Here, we investigate how inorganic carbon limitation modifies the physiology and transcriptome of Nitrosomonas europaea, a model ammonia-oxidizing bacterium, and report on increased production of N₂O, a potent greenhouse gas. This study, along with previous work, suggests that inorganic carbon limitation may be an important factor in controlling N₂O emissions from nitrification in soils and wastewater treatment

Methylglyoxal Induces Apoptosis Mediated by Reactive Oxygen Species in Bovine Retinal Pericytes

One of the histopathologic hallmarks of early diabetic retinopathy is the loss of pericytes. Evidences suggest that the pericyte loss in vivo is mediated by apoptosis. However, the underlying cause of pericyte apoptosis is not fully understood. This study investigated the influence of methylglyoxal (MGO), a reactive α-dicarbonyl compound of glucose metabolism, on apoptotic cell death in bovine retinal pericytes. Analysis of internucleosomal DNA fragmentation by ELISA showed that MGO (200 to 800 µM) induced apoptosis in a concentration-dependent manner. Intracellular reactive oxygen species were generated earlier and the antioxidant, N-acetyl cysteine, inhibited the MGO-induced apoptosis. NF-κB activation and increased caspase-3 activity were detected. Apoptosis was also inhibited by the caspase-3 inhibitor, Z-DEVD-fmk, or the NF-κB inhibitor, pyrrolidine dithiocarbamate. These data suggest that elevated MGO levels observed in diabetes may cause apoptosis in bovine retinal pericytes through an oxidative stress mechanism and suggests that the nuclear activation of NF-κB are involved in the apoptotic process

Methylglyoxal Mediates Adipocyte Proliferation by Increasing Phosphorylation of Akt1

Methylglyoxal (MG) is a highly reactive metabolite physiologically presented in all biological systems. The effects of MG on diabetes and hypertension have been long recognized. In the present study, we investigated the potential role of MG in obesity, one of the most important factors to cause metabolic syndrome. An increased MG accumulation was observed in the adipose tissue of obese Zucker rats. Cell proliferation assay showed that 5–20 µM of MG stimulated the proliferation of 3T3-L1 cells. Further study suggested that accumulated-MG stimulated the phosphorylation of Akt1 and its targets including p21 and p27. The activated Akt1 then increased the activity of CDK2 and accelerated the cell cycle progression of 3T3-L1 cells. The effects of MG were efficiently reversed by advanced glycation end product (AGE) breaker alagebrium and Akt inhibitor SH-6. In summary, our study revealed a previously unrecognized effect of MG in stimulating adipogenesis by up-regulation of Akt signaling pathway and this mechanism might offer a new approach to explain the development of obesity

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