Importance Of Cell Metabolism Research Articles

Depletion and Supplementation of Coenzyme Q10 in Secondary Deficiency Disorders

Coenzyme Q10 (CoQ10) deficiency is broadly divided into two types, primary and secondary. Primary CoQ10 deficiencies are relatively rare disorders resulting from mutations in genes directly involved in the CoQ10 biosynthetic pathway, and are not a subject of this article. Secondary CoQ10 disorders are relatively common, and may occur for a variety of reasons; these include mutations in genes not directly related to the synthetic pathway, oxidative stress induced reduction of CoQ10, and the effects of pharmacological agents such as statins. CoQ10 is of key importance in cell metabolism; in addition to its role in mitochondrial oxidative phosphorylation, it is a major endogenous antioxidant, and has a role in the metabolism of sulphides, lipids and amino acids. Given its importance in cell metabolism, it is unsurprising that secondary CoQ10 deficiency has been linked with a wide range of disorders. In this article, we have reviewed evidence of secondary CoQ10 deficiency in both common and less common disorders, and highlighted those disorders in which CoQ10 supplementation has been shown to be of significant clinical benefit.

Investigation of the multi-targeted protection potential of tannic acid against doxorubicin-induced kidney damage in rats

Doxorubicin (DOX) is an antitumor drug that is powerful but can cause worse outcomes, including nephrotoxicity, and therefore has limited clinical use. Therefore, it is necessary to identify safer agents that can minimize the damage caused by the drug without shifting the treatment performance, in addition to clarifying the underlying mechanisms of DOX-induced aberrant in vivo renal activation. In this study, we tested the prophylactic capacity and mechanisms of action of tannic acid (TA) against DOX-mediated kidney damage in rats and evaluated the nephrotoxic activity of DOX when used with TA. Rats were treated during the two weeks with cumulative (18 mg/kg with six different injections) DOX, daily TA (50 mg/kg), and the DOX + TA combination. Changes in major metabolites and components involved in antioxidant metabolism were evaluated in the kidney tissues of all animals. Further, the gene expression levels of regulatory factors that have critical importance in cell metabolism, inflammation, and apoptosis were investigated. Both biochemical and molecular examinations showed that TA improved DOX-induced dysregulations at both protein and gene levels in the kidneys. Increased lipid peroxidation and decreased glutathione levels were reversed. Consistent with oxidative stress marker metabolites, suppressed antioxidant enzyme activities and transcript levels of antioxidant system members were restored. Of note, combination treatment with TA could overcome doxorubicin-induced gene expressions markedly altered by DOX, suggesting that nephroprotection conferred by TA involved the remodeling of stress resistance, cell metabolism, inflammation, and apoptosis. Collectively, the present in vivo study suggests that TA could be used as a multitarget and effective agent for the mitigation of doxorubicin-induced nephrotoxicity without changing the therapeutic efficacy of the drug.

Liver and brain differential expression of one-carbon metabolism genes during ontogenesis

One-carbon metabolism (1C metabolism) is of paramount importance for cell metabolism and mammalian development. It is involved in the synthesis or modification of a wide variety of compounds such as proteins, lipids, purines, nucleic acids and neurotransmitters. We describe here the evolution of expression of genes related to 1C metabolism during liver and brain ontogeny in mouse. The level of expression of 30 genes involved in 1C metabolism was quantified by RT-qPCR in liver and brain tissues of OF1 mice at E9, E11, E13, E15, E17, P0, P3, P5, P10, P15 developmental stages and in adults. In the liver, hierarchical clustering of the gene expression patterns revealed five distinct clades of genes with a first bifurcating hierarchy distinguishing two main developmental stages before and after E15. In the brain most of the 1C metabolism genes are expressed but at a lower levels. The gene expression of enzymes involved in 1C metabolism show dramatic changes during development that are tissue specific. mRNA expression patterns of all major genes involved in 1C metabolism in liver and brain provide clues about the methylation demand and methylation pathways during embryonic development.

ELECTROLYTES CHANGES IN MALE RATS DEPRIVED OF FEED AND WATER

ABATRACT Electrolytes are of great importance in cell metabolism because they are important cofactors or coenzymes needed for normal functioning of cells. The disturbances of these electrolytes result in changes of cell pH and acid base balance. In order to determine the electrolytes changes following feed and water deprivation in male rats, a total of ten (n=10) male albino rats weighing (152 ± 3.50)g housed in metallic cage were used for this study. The rats were deprived of feed and water consecutively for six days. On the third and sixth days blood samples were obtained for electrolytes studies in the plasma and in the erythrocytes. There were significant increases (P<0.05) in plasma sodium, potassium, calcium, magnesium, chloride and bicarbonate concentrations in comparison to the basal parameters while significant decreases (P<0.05) in erythrocytes sodium, potassium, calcium, magnesium, chloride and bicarbonate concentrations in comparison to the basal parameters were observed. It can be concluded that deprivation of male albino rats of food and water for six consecutive days resulted in perturbation, stress, dehydration and redistribution of electrolytes in various compartments of the cell

New pathogenic variants in COQ4 cause ataxia and neurodevelopmental disorder without detectable CoQ10 deficiency in muscle or skin fibroblasts.

COQ4 is a component of an enzyme complex involved in the biosynthesis of coenzyme Q10 (CoQ10), a molecule with primary importance in cell metabolism. Mutations in the COQ4 gene are responsible for mitochondrial diseases showing heterogeneous age at onset, clinical presentations and association with CoQ10 deficiency. We herein expand the phenotypic and genetic spectrum of COQ4-related diseases, by reporting two patients harboring bi-allelic variants but not showing CoQ10 deficiency. One patient was found to harbor compound heterozygous mutations (specifically, c.577C>T/p.Pro193Ser and the previously reported c.718C>T/p.Arg240Cys) associated with progressive spasticity, while the other harbored two novel missense (c.284G>A/p.Gly95Asp and c.305G>A/p.Arg102His) associated with a neurodevelopmental disorder. Both patients presented motor impairment and ataxia. To further understand the role of COQ4, we performed functional studies in patient-derived fibroblasts, yeast and "crispant" zebrafish larvae. Micro-oxygraphy showed impaired oxygen consumption rates in one patient, while yeast complementation assays showed that all the mutations were presumably disease related. Moreover, characterization of the coq4 F0 CRISPR zebrafish line showed motor defects and cell reduction in a specific area of the hindbrain, a region reminiscent of the human cerebellum. Our expanded phenotype associated with COQ4 mutations allowed us to investigate, for the first time, the role of COQ4 in brain development in vivo.

Characterisation of the Effect of the Spatial Organisation of Hemicellulases on the Hydrolysis of Plant Biomass Polymer.

Synergism between enzymes is of crucial importance in cell metabolism. This synergism occurs often through a spatial organisation favouring proximity and substrate channelling. In this context, we developed a strategy for evaluating the impact of the geometry between two enzymes involved in nature in the recycling of the carbon derived from plant cell wall polymers. By using an innovative covalent association process using two protein fragments, Jo and In, we produced two bi-modular chimeric complexes connecting a xylanase and a xylosidase, involved in the deconstruction of xylose-based plant cell wall polymer. We first show that the intrinsic activity of the individual enzymes was preserved. Small Angle X-rays Scattering (SAXS) analysis of the complexes highlighted two different spatial organisations in solution, affecting both the distance between the enzymes (53 Å and 28 Å) and the distance between the catalytic pockets (94 Å and 75 Å). Reducing sugar and HPAEC-PAD analysis revealed different behaviour regarding the hydrolysis of Beechwood xylan. After 24 h of hydrolysis, one complex was able to release a higher amount of reducing sugar compare to the free enzymes (i.e., 15,640 and 14,549 µM of equivalent xylose, respectively). However, more interestingly, the two complexes were able to release variable percentages of xylooligosaccharides compared to the free enzymes. The structure of the complexes revealed some putative steric hindrance, which impacted both enzymatic efficiency and the product profile. This report shows that controlling the spatial geometry between two enzymes would help to better investigate synergism effect within complex multi-enzymatic machinery and control the final product.

Alterations of the Viable Ileal Microbiota of the Gut Mucosa-Lymph Node Axis in Pigs Fed Phytase and Lactic Acid-Treated Cereals.

The gut-lymph node axis is a critical player in the symbiotic relationship between gut microbiota and the host. However, little is known about the impact of diet-related bacterial shifts in the gut lumen on bacterial translocation into lymph nodes. Here, we (i) characterized changes in the viable microbiota composition along the ileal digesta-mucosa-lymph node axis and (ii) examined the effect of dietary phytase supplementation and lactic acid (LA) soaking of cereals on the bacterial taxonomy along this axis, together with their effect on the mucosal expression of innate immune and barrier function genes in pigs (n = 8/diet). After 18 days on diets, ileal digesta, mucosa, and ileocecal lymph nodes (ICLNs) were collected for RNA isolation and 16S rRNA-based high-resolution community profiling. Bacterial communities were dominated by Lactobacillaceae and Clostridiaceae, with clearly distinguishable profiles at the three sampling sites. Specific bacterial subsampling was indicated by enrichment of the ICLNs with Lactobacillaceae, Lachnospiraceae, Veillonellaceae, and Methanobacteriaceae and less Clostridiaceae, Pasteurellaceae, Helicobacteraceae, and Enterobacteriaceae compared to that of the mucosa. LA treatment of cereals reduced proteolytic taxa in the lumen, including pathobionts like Helicobacteraceae, Campylobacteraceae, and Fusobacteriaceae When combined, phytase- and LA-treated cereals largely increased species richness, while the single treatments reduced Actinobacteria and Bacteroidetes in ICLNs and increased mucosal MUC2 expression. In contrast, phytase reduced mucosal CDH1 expression, indicating altered barrier function with potential effects on bacterial translocation. Overall, both treatments, although often differently, changed the viable microbiome along the digesta-mucosa-lymph node axis in the ileum, probably due to altered substrate availability and microbial-host interactions.IMPORTANCE A host's diet largely determines the gut microbial composition and therefore may influence bacterial translocation into ICLNs. Due to its importance for cell metabolism, the intestinal phosphorus availability, which was modified here by phytase and LA treatment of cereals, affects the intestinal microbiota. Previous studies mainly focused on bacteria in the lumen. The novelty of this work resides mainly in that we report diet-microbe effects along the digesta-mucosa-ICLN axis and linked those effects to mucosal expression of barrier function genes as crucial components for host health. Lymph nodes can serve as reservoir of pathobionts; therefore, present diet-microbiome-host interactions have implications for food safety.

IDH1, a CHOP and C/EBPβ-responsive gene under ER stress, sensitizes human melanoma cells to hypoxia-induced apoptosis

Isocitrate dehydrogenase1 (IDH1) is of great importance in cell metabolism and energy conversion. However, alterations in IDH1 in response to stress and excise-regulated mechanisms are not well described. Here we investigated gene expression profiles under ER stress in melanoma cells and found that IDH1 was dramatically increased with ER stress induced by tunicamycin. Elevated IDH1 subsequently sensitized human melanoma cells to hypoxia-induced apoptosis and promoted HIF-1α degradation. In addition, we revealed that CHOP and C/EBPβ were involved in hypoxia-induced apoptosis via transcriptional regulation of IDH1 expression. Our data indicate that IDH1, regulated by CHOP and C/EBPβ in response to ER stress treatment, inhibits survival of melanoma cells under hypoxia and promotes HIF-1α degradation. Therefore, we propose that IDH1 may serve as a valuable target for melanoma therapy.

IDH1 Overexpression Induced Chemotherapy Resistance and IDH1 Mutation Enhanced Chemotherapy Sensitivity in Glioma Cells in Vitro and in Vivo

Isocitrate dehydrogenase (IDH) is of great importance in cell metabolism and energy conversion. IDH mutation in glioma cells is reported to be associated with an increased overall survival. However, effects biological behavior of therapy of gliomas are unclear. Here, we investigated the influence of wild-type and mutated IDH genes on glioma cell biological behavior and response to chemotherapy. Relevant mechanisms were further explored. We designed our study on the background of the IDHR132H mutation. Stable cell lines were constructed by transfection. The CCK-8 method was used to assess cell proliferation, flow cytometry for the cell cycle and cell apoptosis, and the transwell method for cell invasion. Nude mouse models were employed to determine tumorigenesis and sensitivity to chemotherapy. Western blotting was used to detect relevant protein expression levels. We found that overexpression of wild IDH1 gene did not cause changes in the cell cycle, apoptosis and invasion ability. However, it resulted in chemotherapy resistance to a high dose of temozolomide (TMZ) in vivo and in vitro. The IDH1 mutation caused cell cycle arrest in G1 stage and a reduction of proliferation and invasion ability, while raising sensitivity to chemotherapy. This may provide an explanation for the better prognosis of IDH1 mutated glioma patients and the relative worse prognosis of their wild-type IDH1 counterparts. We also expect IDH1 mutations may be optimized as new targets to improve the prognosis of glioma patients.

P-bodies and mitochondria: Which place in RNA interference?

Micro-RNAs (miRNAs) are major actors of RNA interference (RNAi), a regulation pathway which leads to translational repression and/or degradation of specific mRNAs. They provide target specificity by incorporating into the RISC complex and guiding its binding to mRNA. Since the discovery of RNAi, many progresses have been made on the mechanism of action of the RISC complex and on the identification of target mRNAs. However, the regulation of RNAi has been poorly investigated so far. Recently, various studies have revealed physical and functional relationships between RNAi, P-bodies and mitochondria. This review intends to recapitulate these data and discuss their potential importance in cell metabolism.

Phosphoanalogues of amino acids involved in methionine metabolism as a new source of antiviral compounds

84 Biological methylation is of primary importance in cell metabolism [1]. The major donor of methyl groups used in biological methylation is S-adenosylmethionine (Met(Ado)), which is converted to S-adenosylhomocysteine Hcy(Ado), the only inhibitor of methylation reactions. The intracellular level of Met(Ado) is regulated by hydrolase (Fig. 1). The nucleoside inhibitors of this enzyme increase the concentration of S-adenosylhomocysteine, which results in suppression of activity of Met(Ado)-dependent methyltransferases, including viral mRNA methylases, and determines the antiviral activity of such compounds [1, 2]. The selectivity of effect of hydrolase inhibitors is low. These compounds inhibit methylation of the main classes of biological molecules, which determines the toxicity of antiviral compounds belonging to the group of nucleoside inhibitors. The search for specific inhibitors of Met(Ado) exchange and methionine metabolism (Fig. 1) remains to be a promising direction in the chemotherapy of viral infections [2].

CELL‐ASSOCIATED PROTEOLYTIC ENZYMES FROM MARINE PHYTOPLANKTON1

ABSTRACTDespite their central importance in cell metabolism, little is known about proteases in marine phytoplankton. We surveyed caseinolytic and leucine aminopeptidase (LAP) activities in log‐phase cultures of the chlorophyte Dunaliella tertiolecta Butcher, the diatom Thalassiosira weissflogii (Gru.) Fryxell et Hasle, the chrysophyte Isochrysis galbana Parke, the coccolithophorid Emiliania huxleyi (Lohm.) Hay et Mohler, and the cyanobacterium Synechococcus sp. (WH 5701). LAP activity was very low at pH &lt; 6 and peaked between pH 7.5 and 8.5 in all species, whereas caseinolytic activity in most species showed only minor peaks in the pH 4–5 range and broad maxima above pH 8. Thus, acidic vacuolar proteases apparently represented only a small fraction of total protease activity. Attempts to classify proteases using selective inhibitors were inconclusive. Neither the serine/cysteine protease inhibitor leupeptin nor the aspartic protease inhibitor pepstatin. A inhibited caseinolytic or LAP activity in any species. The metalloprotease inhibitor EDTA was only effective against LAP activity in some species, causing average decreases of 30–50%, whereas the cysteine/serine protease inhibitor phenyl methyl sulfonylfluoride achieved at best a 30–60% decrease in caseinolytic activity. Caseinolytic activities were remarkably stable. At pH 7.5 and 25°C, extracts of D. tertiolecta, E. huxleyi, and Synechococcus showed no changes in activity after 24 h, whereas activity declined by less than 50% in the other species. Incubation of cell extracts for 1 h at 25°C in pH 7.5 buffer did not alter patterns of cell proteins, suggesting that endogenous proteases did not effectively degrade endogenous proteins. Casein zymograms were used to identify &gt;200‐and &lt;20‐kDa proteases in homogenates of log‐phase T. weissflogii; only the smaller protease was found in D. tertiolecta. Antibodies to the ATPase subunit (C) of the conserved, chloroplastic Clp protease from Pisum cross‐reacted with proteins in Synechococcus, D. tertiolecta, and I. galbana, but no cross‐reactions were found for any species with antibodies against the ClpP subunit from either E. coli or Nicotiana. Our results show that phytoplankton contain a diverse complement of proteases with novel characteristics.

A quantitative cytochemical method for ornithine decarboxylase activity.

Although decarboxylases, particularly ornithine decarboxylase, are of considerable importance in cell metabolism, it has been impossible to demonstrate their activity histochemically, as this depends on trapping carbon dioxide at neutral pH values. A new reagent, lead hydroxyisobutyrate, has been shown capable of such trapping. It has been applied to the demonstration of ornithine decarboxylase activity in mouse kidney. Optimal concentrations of substrate, co-factor and trapping agent, as well as the pH optimum, have been determined for cryostat sections stabilized with a collagen polypeptide. The activity was inhibited by the specific ornithine decarboxylase inhibitor alpha-difluoromethyl ornithine.

Über den Einfluss hypotonischen Milieus auf den Stoffwechsel dereprimierter pflanzlicher Gewebe

AbstractDuring investigations of their metabolism fragments of plant tissue are most commonly incubated in watery solutions in order to replace the conditions within the intact organ approximately. — This paper reports experiments performed to investigate the influence of a hypotonic medium on several parameters of importance in cell metabolism (protein synthesis, enzymatic activity, concentrations of metabolic intermediates, respiration and cell division). — It could be shown that protein synthesis is severely inhibited in hypotonically exposed potato tuber discs. As a consequence the activities of two dehydrogenases of the pentose phosphate shunt (glucose‐6‐phosphate‐ and 6‐phosphogluconate‐dehydrogenase) are very low as compared with tissue in air. Since the activated pentose shunt evidently contributes to the respiratory reaction after derepression of the tissue, lowered activities of these dehydrogenases must consequently result in lower respiratory activity. This is actually realized in washed tissue. Likewise the mitotic activity is inhibited to a considerable extent. — The destruction of permeability barriers within the cell as a consequence of slicing causes leakage of a variety of metabolites such as glucose, glucose‐6‐phosphate, fructose‐6‐phosphate and pyruvate. Thus leaching of metabolic active substances is certainly one of the causal factors in the complex reaction of tissue slices exposed to a hypotonic medium, although such important parameters as changed gas conditions and the various effects of altered hydration of cell cytoplasm must be considered.