Liver damage and caspase-dependent apoptosis is related to protein malnutrition in mice: effect of methionine

This study aimed to determine whether the effects on the mouse liver caused by three periods of feeding a protein-free diet for 5 days followed by a normal complete diet for 5 days (3PFD-CD) are prevented by a constant methionine supply (3PFD+Met-CD). The expressions of carbonic anhydrase III (CAIII), fatty acid synthase (FAS), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and glutathione S-transferase P1 (GSTP1) were assessed by proteomics and reverse transcriptase-polymerase chain reactions. The liver redox status was examined by measuring the activities of superoxide dismutase (SOD) and catalase (CAT), as well as protein carbonylation. Because oxidative stress can result in apoptosis, the activity and content of caspase-3, as well as the x-linked inhibitor of the apoptosis protein (XIAP) and mitochondrial caspase-independent apoptosis inducing factor (AIF) contents were assessed. In addition, the liver histomorphology was examined. Compared to the controls fed a normal complete diet throughout, feeding with 3PFD-CD increased the FAS content, decreased the CAIII content, decreased both the SOD and CAT activities, and increased protein carbonylation. It also activated caspase-3, decreased the XIAP content, decreased the AIF content, increased the number of GSTP1-positive foci and caspase-3-positive cells, and caused fatty livers. Conversely, the changes were lessened to varying degrees in mice fed 3PFD+Met-CD. The present results indicate that a regular Met supply lessens the biochemical changes, damage, and caspase-dependent apoptosis provoked by recurrent dietary amino acid deprivation in the mouse liver.

O-GlcNAcylation as a novel ammonia-induced posttranslational protein modification in cultured rat astrocytes

Hepatic encephalopathy (HE) is a clinical manifestation of a low grade cerebral edema with a mutual interrelationship between osmotic- and oxidative stress. This leads to RNA oxidation and posttranslational protein modifications such as protein tyrosine nitration with pathophysiological relevance. Here, we report on O-GlcNAcylation as another ammonia-induced posttranslational protein modification in cultured rat astrocytes. NH4Cl induced O-GlcNAcylation of distinct proteins (25-250 kDa) in astrocytes in a dose- and time-dependent manner. Exposure of astrocytes to NH4Cl (5 mmol/l) for 48 h and 72 h significantly increased protein O-GlcNAcylation by about 2-fold and 4-fold, respectively. NH4Cl at a concentration of 1 mmol/l was sufficient to double protein O-GlcNAcylation in astrocytes after 72 h as compared to untreated controls. Ammonia-induced protein O-GlcNAcylation was sensitive towards glutamine-synthetase inhibition by methionine sulfoximine (MSO), but was not induced by hypoosmolarity (205 mosmol/l) or CH3NH3Cl (5 mmol/l). Increased protein O-GlcNAcylation in NH4Cl (5 mmol/l, 48 h)-treated astrocytes was fully reversible within 24 h after withdrawal of NH4Cl from culture medium. Amongst the proteins which are O-GlcNAcylated in response to ammonia, GAPDH was identified. It is concluded that ammonia induces reversible protein O-GlcNAcylation in astrocytes that depends on glutamine synthesis but not on astrocyte swelling per se or ammonia-induced pH-changes. In view of the complex involvement of O-GlcNAcylation in cell regulation, such as energy metabolism, apoptosis and circadian rhythmicity and in pathologies, such as neurodegenerative diseases, O-GlcNAcylation might contribute to the pathophysiology of hepatic encephalopathy.

Validation of housekeeping genes in the brains of rats submitted to chronic intermittent hypoxia, a sleep apnea model

Obstructive sleep apnea (OSA) is a syndrome characterized by intermittent nocturnal hypoxia, sleep fragmentation, hypercapnia and respiratory effort, and it has been associated with several complications, such as diabetes, hypertension and obesity. Quantitative real-time PCR has been performed in previous OSA-related studies; however, these studies were not validated using proper reference genes. We have examined the effects of chronic intermittent hypoxia (CIH), which is an experimental model mainly of cardiovascular consequences of OSA, on reference genes, including beta-actin, beta-2-microglobulin, glyceraldehyde-3-phosphate dehydrogenase, hypoxanthine guanine phosphoribosyl transferase and eukaryotic 18S rRNA, in different areas of the brain. All stability analyses were performed using the geNorm, Normfinder and BestKeeper software programs. With exception of the 18S rRNA, all of the evaluated genes were shown to be stable following CIH exposure. However, gene stability rankings were dependent on the area of the brain that was analyzed and varied according to the software that was used. This study demonstrated that CIH affects various brain structures differently. With the exception of the 18S rRNA, all of the tested genes are suitable for use as housekeeping genes in expression analyses.

Hydrogen sulfide and nitric oxide metabolites in the blood of free-ranging brown bears and their potential roles in hibernation

During winter hibernation, brown bears (Ursus arctos) lie in dens for half a year without eating while their basal metabolism is largely suppressed. To understand the underlying mechanisms of metabolic depression in hibernation, we measured type and content of blood metabolites of two ubiquitous inhibitors of mitochondrial respiration, hydrogen sulfide (H2S) and nitric oxide (NO), in winter-hibernating and summer-active free-ranging Scandinavian brown bears. We found that levels of sulfide metabolites were overall similar in summer-active and hibernating bears but their composition in the plasma differed significantly, with a decrease in bound sulfane sulfur in hibernation. High levels of unbound free sulfide correlated with high levels of cysteine (Cys) and with low levels of bound sulfane sulfur, indicating that during hibernation H2S, in addition to being formed enzymatically from the substrate Cys, may also be regenerated from its oxidation products, including thiosulfate and polysulfides. In the absence of any dietary intake, this shift in the mode of H2S synthesis would help preserve free Cys for synthesis of glutathione (GSH), a major antioxidant found at high levels in the red blood cells of hibernating bears. In contrast, circulating nitrite and erythrocytic S-nitrosation of glyceraldehyde-3-phosphate dehydrogenase, taken as markers of NO metabolism, did not change appreciably. Our findings reveal that remodeling of H2S metabolism and enhanced intracellular GSH levels are hallmarks of the aerobic metabolic suppression of hibernating bears.

Cytosolic phosphorylating glyceraldehyde-3-phosphate dehydrogenases affect Arabidopsis cellular metabolism and promote seed oil accumulation

The cytosolic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPC) catalyzes a key reaction in glycolysis, but its contribution to plant metabolism and growth are not well defined. Here, we show that two cytosolic GAPCs play important roles in cellular metabolism and seed oil accumulation. Knockout or overexpression of GAPCs caused significant changes in the level of intermediates in the glycolytic pathway and the ratios of ATP/ADP and NAD(P)H/NAD(P). Two double knockout seeds had ∼3% of dry weight decrease in oil content compared with that of the wild type. In transgenic seeds under the constitutive 35S promoter, oil content was increased up to 42% of dry weight compared with 36% in the wild type and the fatty acid composition was altered; however, these transgenic lines exhibited decreased fertility. Seed-specific overexpression lines had >3% increase in seed oil without compromised seed yield or fecundity. The results demonstrate that GAPC levels play important roles in the overall cellular production of reductants, energy, and carbohydrate metabolites and that GAPC levels are directly correlated with seed oil accumulation. Changes in cellular metabolites and cofactor levels highlight the complexity and tolerance of Arabidopsis thaliana cells to the metabolic perturbation. Further implications for metabolic engineering of seed oil production are discussed.

Tropheryma whipplei, the agent of Whipple's disease, affects the early to late phagosome transition and survives in a Rab5- and Rab7-positive compartment

Tropheryma whipplei, the agent of Whipple's disease, inhibits phago-lysosome biogenesis to create a suitable niche for its survival and replication in macrophages. To understand the mechanism by which it subverts phagosome maturation, we used biochemical and cell biological approaches to purify and characterise the intracellular compartment where Tropheryma whipplei resides using mouse bone-marrow-derived macrophages. We showed that in addition to Lamp-1, the Tropheryma whipplei phagosome is positive for Rab5 and Rab7, two GTPases required for the early to late phagosome transition. Unlike other pathogens, inhibition of PI(3)P production was not the mechanism for Rab5 stabilisation at the phagosome. Overexpression of the inactive, GDP-bound form of Rab5 bypassed the pathogen-induced blockade of phago-lysosome biogenesis. This suggests that Tropheryma whipplei blocks the switch from Rab5 to Rab7 by acting on the Rab5 GTPase cycle. A bio-informatic analysis of the Tropheryma whipplei genome revealed a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) homologous with the GAPDH of Listeria monocytogenes, and this may be the bacterial protein responsible for blocking Rab5 activity. To our knowledge, Tropheryma whipplei is the first pathogen described to induce a “chimeric” phagosome stably expressing both Rab5 and Rab7, suggesting a novel and specific mechanism for subverting phagosome maturation.

Lack of malate valve capacities lead to improved N-assimilation and growth in transgenic A. thaliana plants

In this study we analyzed the relationship between malate valve capacities, N-assimilation, and energy metabolism. We used transgenic plants either lacking the chloroplast NADP-dependent malate dehydrogenase or mutants with a decreased transcript level of the plastid-localized NAD-dependent malate dehydrogenase. Plants were grown on nitrate or ammonium, respectively, as the sole N-source and transcripts were analyzed by qRT-PCR. We could show that the lack of malate valve capacities enhances N-assimilation and plastidial glycolysis by increasing transcript levels of Fd-GOGATs or NADH-GOGAT and plastidic NAD-GAPDHs (GapCps), respectively. Based on our results, we conclude that the lack of malate valve capacities is balanced by an increase of the activity of plastid-localized glycolysis in order to cover the high demand for plastidial ATP, stressing the importance of the plastids for energy metabolism in plant cells.

Yeast Tdh3 (glyceraldehyde 3-phosphate dehydrogenase) is a Sir2-interacting factor that regulates transcriptional silencing and rDNA recombination

Sir2 is an NAD(+)-dependent histone deacetylase required to mediate transcriptional silencing and suppress rDNA recombination in budding yeast. We previously identified Tdh3, a glyceraldehyde 3-phosphate dehydrogenase (GAPDH), as a high expression suppressor of the lethality caused by Sir2 overexpression in yeast cells. Here we show that Tdh3 interacts with Sir2, localizes to silent chromatin in a Sir2-dependent manner, and promotes normal silencing at the telomere and rDNA. Characterization of specific TDH3 alleles suggests that Tdh3's influence on silencing requires nuclear localization but does not correlate with its catalytic activity. Interestingly, a genetic assay suggests that Tdh3, an NAD(+)-binding protein, influences nuclear NAD(+) levels; we speculate that Tdh3 links nuclear Sir2 with NAD(+) from the cytoplasm.

Effect of long-term human exposure to environmental heavy metals on the expression of detoxification and DNA repair genes

The present study was designed to evaluate the influence of long-term environmental human exposure to three heavy metals, lead (Pb), cadmium (Cd), and mercury (Hg), on the expression of detoxifying, xenobiotic metabolizing, and DNA repair genes in Mahd Ad-Dahab city. The study groups consisted of 40 healthy male residents (heavy metal-exposed) and 20 healthy male from Riyadh city, 700 km away, and served as control group. The heavy metal-exposed group with high exposure to Pb, Cd, or Hg was divided into three subgroups Pb-, Cd-, and Hg-exposed groups, respectively. The mRNA expression levels of detoxifying, NQO1, HO-1, GSTA1, MT-1, and HSP70, were significantly decreased in all heavy metal-exposed group as compared to control group. This was accompanied with a proportional decrease in the expression of xenobiotic metabolizing gene, cytochrome P4501A1. On the other hand, the DNA repair gene OGG1 and the 8-OHdG level were dramatically inhibited in Cd-exposed group only.

Glyceraldehyde-3-phosphate dehydrogenase gene over expression correlates with poor prognosis in non small cell lung cancer patients

BACKGROUND

Glycolysis in presence of oxygen with high glucose consumption is known to be the metabolism of choice in many tumors. In lung cancer this phenomenon is routinely exploited in diagnostic PET imaging of fluorodeoxyglucose uptake, but not much is known about the prognostic capabilities of glycolysis level assessment in resected lung tumor samples.

METHODS

In this retrospective study, we used real time polymerase chain reaction(RQ-PCR) to assess the expression level of the gene for Glyceraldehyde 3-phosphate dehydrogenase(GAPDH), key enzyme for glucose breakdown, in tumor samples from 82 consecutive early stages resected non small cell lung cancer(NSCLC) patients. We then compared our results in six large publicly available NSCLC microarray datasets collecting data from over 1250 total patients.

RESULTS

In our study GAPDH gene over expression was found to be an adverse prognostic factor in early stages NSCLC (n = 82 HR = 1.30 p = 0.050). This result was confirmed in 5 of 6 public datasets analyzed: Shedden et al. 2008: n = 442 HR = 1.54 p < 0.0001; Lee et al. 2008: n = 138 HR = 1.31 p = 0.043; Tomida et al. 2009: n = 117 HR = 1.59 p = 0.004; Roepman et al. 2009: n = 172 (TPI1 gene) HR = 1.51 p = 0.009; Okayama et al. 2012: n = 226 HR = 3.19 p < 0.0001; Botling et al. 2013: n = 196 HR = 1.00 p = 0.97). Furthermore, in the large and clinically well annotated Shedden et al. microarray dataset, GAPDH hazard ratio did not change whether calculated for the whole dataset or for the subgroup of adjuvant naive patients only (n = 330 HR = 1.49 p < 0.0001).

CONCLUSION

GAPDH gene over expression in resected tumor samples is an adverse prognostic factor in NSCLC. Our results confirm the prognostic value of glucose metabolism assessment in NSCLC.

The Roles of Moonlighting Proteins in Bacteria

Moonlighting proteins, characterized by their multiple autonomous functions, have been detected in bacteria. Surprisingly, many of these proteins are conserved and involved in metabolic pathway or the cell stress response. They localise to the bacterial surface to take on additional activities, which have been hypothesised to contribute to bacterial virulence or bacterial benefit. In this review, we compare the functions of moonlighting proteins in bacteria, describe the structural basis of moonlighting functions, and summarise the regulation of secretion and localisation of moonlighting proteins.

Differential regulation of macropinocytosis in macrophages by cytokines: implications for foam cell formation and atherosclerosis

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Macrophages can internalise LDL through scavenger receptor-independent mechanisms.

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Macropinocytosis has been shown to contribute significantly to foam cell formation.

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Cytokines such as TGF-β, IL-33, IFN-γ and IL-17A can modulate macropinocytosis.

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TGF-β mediated inhibition of macropinocytosis is a Smad-2/-3-independent process.

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Macropinocytosis is a promising target for therapeutic intervention of atherosclerosis.

A key event during the formation of lipid-rich foam cells during the progression of atherosclerosis is the uptake of modified low-density lipoproteins (LDL) by macrophages in response to atherogenic mediators in the arterial intima. In addition to scavenger receptor-dependent uptake of LDL, macropinocytosis is known to facilitate the uptake of LDL through the constitutive and passive internalization of large quantities of extracellular solute. In this study we confirm the ability of macropinocytosis to facilitate the uptake of modified LDL by human macrophages and show its modulation by TGF-β, IFN-γ, IL-17A and IL-33. Furthermore we show that the TGF-β-mediated inhibition of macropinocytosis is a Smad-2/-3-independent process.

An improved infectivity assay combining cell culture with real-time PCR for rapid quantification of human adenoviruses 41 and semi-quantification of human adenovirus in sewage

A protocol for the rapid detection and semi-quantification of human enteric adenovirus based on the quantification of viral mRNA during cell culture infectivity assay was developed. Infectivity assays for adenovirus incorporated cell culture and reverse transcription real-time PCR, where viral mRNA detection was used to monitor the progress of adenovirus infection (CC/mRNA qPCR). The cell line used was G293. This specific infectivity assay was calibrated against different initial concentrations of human adenovirus 41. In addition, the expression of the host's housekeeping (HK) gene, GAPDH, served as internal control for the mRNA assays for quality assurance of the mRNA extraction and reverse transcription steps. The concentrations of infectious human adenoviruses in different sewage samples were estimated semi-quantitatively using the CC/mRNA qPCR assay and calibration obtained for adenovirus 41. A linear relationship between concentrations of viral mRNA (hexon gene) and infectious units was observed between 10(7) to 10(1) infectious units per assay (R(2) = 0.97) in samples analyzed 3-5 days post infection. The expressions of host cell GAPDH gene were not significantly affected by infections with different concentrations of human adenovirus 41, and between virus positive and negative cell cultures (p > 0.1). The estimated concentrations of human adenoviruses in sewage samples ranged between 10(2) to 10(3) mRNA-IU/L. Most of the viruses detected in sewage samples were from human adenovirus species F. The CC/mRNA qPCR assay can be used for quantifying infectious human adenovirus 41, estimating the levels of human adenoviruses in sewage samples, and applied to other sample settings. The CC/mRNA qPCR protocol described here represents an improvement in the detection of human enteric adenoviruses by reducing incubation time (5 days); whereas the conventional cell culture method requires longer incubation periods (10-20 days). More importantly, this protocol can be used to more rapidly and semi-quantitatively estimate the levels of infectious human adenoviruses in environmental samples.

Nuclear accumulation of cytosolic glyceraldehyde-3-phosphate dehydrogenase in cadmium-stressed Arabidopsis roots

NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a ubiquitous enzyme involved in the glycolytic pathway. It has been widely demonstrated that mammalian GAPDH, in addition to its role in glycolysis, fulfills alternative functions mainly linked to its susceptibility to oxidative posttranslational modifications. Here, we investigated the responses of Arabidopsis (Arabidopsis thaliana) cytosolic GAPDH isoenzymes GAPC1 and GAPC2 to cadmium-induced stress in seedlings roots. GAPC1 was more responsive to cadmium than GAPC2 at the transcriptional level. In vivo, cadmium treatments induced different concomitant effects, including (1) nitric oxide accumulation, (2) cytosolic oxidation (e.g. oxidation of the redox-sensitive Green fluorescent protein2 probe), (3) activation of the GAPC1 promoter, (4) GAPC1 protein accumulation in enzymatically inactive form, and (5) strong relocalization of GAPC1 to the nucleus. All these effects were detected in the same zone of the root tip. In vitro, GAPC1 was inactivated by either nitric oxide donors or hydrogen peroxide, but no inhibition was directly provided by cadmium. Interestingly, nuclear relocalization of GAPC1 under cadmium-induced oxidative stress was stimulated, rather than inhibited, by mutating into serine the catalytic cysteine of GAPC1 (C155S), excluding an essential role of GAPC1 nitrosylation in the mechanism of nuclear relocalization, as found in mammalian cells. Although the function of GAPC1 in the nucleus is unknown, our results suggest that glycolytic GAPC1, through its high sensitivity to the cellular redox state, may play a role in oxidative stress signaling or protection in plants.

A differential redox regulation of the pathways metabolizing glyceraldehyde-3-phosphate tunes the production of reducing power in the cytosol of plant cells

Adaptation to aerobic life leads organisms to sense reactive oxygen species and use the signal for coordination of the entire metabolism. Glycolysis in plants is a particular network where specific steps, like oxidation of glyceraldehydes-3-phosphate (Ga3P), are critical in order for it to function. The triose-phosphate can be converted into 3-phosphoglycerate through the phosphorylating Ga3P dehydrogenase (Ga3PDHase, EC 1.2.1.12) producing ATP and NADH, or via the non-phosphorylating enzyme (np-Ga3PDHase; EC 1.2.1.9) generating NADPH. In this work we found redox regulation to be a posttranslational mechanism allowing the fine-tuning of the triose-phosphate fate. Both enzymes were inactivated after oxidation by reactive oxygen and nitrogen species. Kinetic studies determined that Ga3PDHase is marked (63-fold) more sensitive to oxidants than np-Ga3PDHase. Thioredoxin-h reverted the oxidation of both enzymes (although with differences between them), suggesting a physiological redox regulation. The results support a metabolic scenario where the cytosolic triose-phosphate dehydrogenases are regulated under changeable redox conditions. This would allow coordinate production of NADPH or ATP through glycolysis, with oxidative signals triggering reducing power synthesis in the cytosol. The NADPH increment would favor antioxidant responses to cope with the oxidative situation, while the thioredoxin system would positively feedback NADPH production by maintaining np-Ga3PDHase at its reduced active state.

Exploration of CP12 conformational changes and of quaternary structural properties using electrospray ionization traveling wave ion mobility mass spectrometry

RATIONALE

CP12 is a small chloroplast protein involved in the Benson-Calvin cycle. Since it was demonstrated that the CP12 protein shared different conformational properties between reduced and oxidized states we took advantage of the segregational properties of the Traveling Wave Ion Mobility (TWIM) guide to study subtle conformational changes related to redox changes.

METHODS

Electrospray ionization mass (ESI-MS) spectra of the CP12 protein were recorded in the positive ion mode using an ESI source fitted on a quadrupole time-of-flight (QToF) hybrid mass spectrometer equipped with a TWIM cell (Synapt HDMS G1, Waters Corp., Manchester) under non-denaturing conditions. Non-covalent experiments were performed using the same instrument without the use of the TWIM device.

RESULTS

Whatever the CP12 form studied, our results showed that CP12 protein was represented by two conformers in equilibrium that displayed very slight differences. These observations led us to propose that CP12 protein structure is rather undergoing transient subtle structural changes than having two different conformational populations in solution. In addition, using non-denaturing experiments, NAD and CP12 stoichiometry were determined with respect to the GAPDH tetramer and the redox state of CP12.

CONCLUSIONS

In this study we showed that the use of the segregational property of the ion mobility (TWIM, Synapt G1 HDMS, Waters, Manchester, UK) allowed differentiation of subtle conformational changes between redox states of the CP12 protein. Standard non-denaturing experiments revealed different binding stoichiometry according to the redox state of the CP12 protein.

LAMP2A overexpression in breast tumors promotes cancer cell survival via chaperone-mediated autophagy

Lysosome-associated membrane protein type 2A (LAMP2A) is a key protein in the chaperone-mediated autophagy (CMA) pathway. LAMP2A helps in lysosomal uptake of modified and oxidatively damaged proteins directly into the lumen of lysosomes for degradation and protein turnover. Elevated expression of LAMP2A was observed in breast tumor tissues of all patients under investigation, suggesting a survival mechanism via CMA and LAMP2A. Reduced expression of the CMA substrates, GAPDH and PKM, was observed in most of the breast tumor tissues when compared with the normal adjacent tissues. Reactive oxygen species (ROS) mediated oxidative stress damages regulatory cellular components such as DNA, proteins and/or lipids. Protein carbonyl content (PCC) is widely used as a measure of total protein oxidation in cells. Ectopic expression of LAMP2A reduces PCC and thereby promotes cell survival during oxidative stress. Furthermore, inhibition of LAMP2A stimulates accumulation of GAPDH, AKT1 phosphorylation, generation of ROS, and induction of cellular apoptosis in breast cancer cells. Doxorubicin, which is a chemotherapeutic drug, often becomes ineffective against tumor cells with time due to chemotherapeutic resistance. Breast cancer cells deficient of LAMP2A demonstrate increased sensitivity to the drug. Thus, inhibiting CMA activity in breast tumor cells can be exploited as a potential therapeutic application in the treatment of breast cancer.

Expression of tlr4, md2 and cd14 in equine blood leukocytes during endotoxin infusion and in intestinal tissues from healthy horses

The expression of tlr4, md2 and cd14 was studied in equine blood leukocytes and in intestinal samples using real time PCR. The stability of three commonly used reference genes, glyceraldehyde-3P-dehydrogenase (GAPDH), hypoxantine ribosyltransferase (HPRT) and succinate dehydrogenase complex subunit A (SDHA), was evaluated using qbase(PLUS). The equine peripheral blood mononuclear cells (eqPBMC) examined were either stimulated in vitro with Phorbol 12-myristate 13-acetate (PMA) and ionomycin or with the CpG oligodeoxynuclotide 2216 (CpG-ODN 2216) or obtained from horses before, during and after infusion of endotoxin. Intestinal tissue from healthy horses was sampled at ileum, right dorsal colon and rectum. Ranking of the three reference genes used for normalisation identified the combination HPRT/SDHA as most suitable both when determined ex vivo in leukocytes obtained from experimentally induced endotoxaemia and in eqPBMC activated in vitro while HPRT/GAPDH were most appropriate for the intestinal samples. The relative amounts of mRNA for TLR4 and MD-2 increased threefold during in vitro activation of the cells with CpG-ODN 2216 but was decreased in cultures stimulated with PMA/ionomycin. A transient elevation in the transcription of tlr4 and md2 was also evident for equine blood leukocytes following endotoxaemia. The levels of mRNA for CD14 on the other hand remained unaffected both during the induction of endotoxaemia and in the in vitro stimulated PBMCs. A low steady expression of TLR4, MD-2 and CD14 mRNA was demonstrated for the intestinal samples with no variation between the intestinal segments analysed. Thus, the foundation for real time PCR based levels of analysis of mRNA for all three components in the equine LPS receptor complex in different intestinal segments was set, making it possible to carry out future expression studies on clinical material.

[Involvement of inhibition of nucleus GAPDH over-expression in erythropoietin's reduction of neuronal apoptosis induced by brain ischemia/reperfusion in rats]

To study whether recombinant human erythropoietin (rhEPO) reduces neuronal apoptosis through inhibiting over-expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in nucleus induced by brain ischemia/reperfusion in rats, 48 adult Sprague-Dawley rats were randomly divided into 3 groups: sham, saline and EPO groups. Animal models of brain ischemia/reperfusion were established by middle cerebral artery occlusion in rats. The effects of EPO on the sizes of ischemia tissue were observed by TTC staining. The over-expression of GAPDH in nucleus was detected by Hoechst-33258 and anti-GAPDH antibody double staining. The neuronal apoptosis in penumbral was detected by Nissl's staining and Hoechst-33258 immunofluorescence, respectively. The results showed that rhEPO treatment (3 000 U/kg, three times daily, i.p.) apparently reduced the sizes of infarct brain tissue in ischemia/reperfusion rats. rhEPO inhibited over-expression of GAPDH in nucleus of apoptotic neurons. In the meantime rhEPO decreased the number of apoptotic neurons in ischemia/reperfusion rats. These results suggest that rhEPO may induced reduction of neuronal apoptosis in penumbra may be through inhibiting over-expression of GAPDH in nucleus of apoptotic neurons induced by ischemia/reperfusion. Reduction of GAPDH over-expression in nucleus may play a pivotal role in EPO inhibiting neuronal apoptosis in cerebral ischemia/reperfusion rats, providing experimental evidence for EPO neuro-protecting effects against ischemia/reperfusion.

AIRE-induced apoptosis is associated with nuclear translocation of stress sensor protein GAPDH

AIRE (Autoimmune Regulator) has a central role in the transcriptional regulation of self-antigens in medullary thymic epithelial cells, which is necessary for negative selection of autoreactive T cells. Recent data have shown that AIRE can also induce apoptosis, which may be linked to cross-presentation of these self-antigens. Here we studied AIRE-induced apoptosis using AIRE over-expression in a thymic epithelial cell line as well as doxycycline-inducible HEK293 cells. We show that the HSR/CARD domain in AIRE together with a nuclear localization signal is sufficient to induce apoptosis. In the nuclei of AIRE-positive cells, we also found an increased accumulation of a glycolytic enzyme, glyceraldehyde-3-phosphate (GAPDH) reflecting cellular stress and apoptosis. Additionally, AIRE-induced apoptosis was inhibited with an anti-apoptotic agent deprenyl that blocks GAPDH nitrosylation and nuclear translocation. We propose that the AIRE-induced apoptosis pathway is associated with GAPDH nuclear translocation and induction of NO-induced cellular stress in AIRE-expressing cells.

A simple, noninvasive and efficient method for transdermal delivery of siRNA

Effective delivery of therapeutic agents is the most challenging hurdle in the use of RNA interference for research and in the clinic. Here, we assessed whether a short synthetic peptide, ACSSSPSKHCG (TD-1), could be transported through rat footpad (follicle-free) skin and efficiently deliver small interfering RNA (siRNA) to knock down a target gene. Fluorescence microscopy revealed that topical co-administration of FITC-labeled TD-1 and FAM-labeled siRNA distributed uniformly from the epidermis to the subcutaneous tissue of rat footpad skin. Transmission electron microscopy revealed the absence of cell-cell junctions and enlarged spaces between epithelial cells in the TD-1-treated footpad skin. TD-1 delivery of anti-GAPDH siRNA significantly reduced the level of GAPDH in 72 h. TD-1 can create a transient opening in non-follicle rat skin for delivery of siRNA and reveal a novel mechanism of transdermal delivery of TD-1 and siRNA into the epidermis for gene knockdown. The system might have potential for siRNA delivery in skin for drug therapy.

Group B streptococcus GAPDH is released upon cell lysis, associates with bacterial surface, and induces apoptosis in murine macrophages

Glyceraldehyde 3-phosphate dehydrogenases (GAPDH) are cytoplasmic glycolytic enzymes that, despite lacking identifiable secretion signals, have been detected at the surface of several prokaryotic and eukaryotic organisms where they exhibit non-glycolytic functions including adhesion to host components. Group B Streptococcus (GBS) is a human commensal bacterium that has the capacity to cause life-threatening meningitis and septicemia in newborns. Electron microscopy and fluorescence-activated cell sorter (FACS) analysis demonstrated the surface localization of GAPDH in GBS. By addressing the question of GAPDH export to the cell surface of GBS strain NEM316 and isogenic mutant derivatives of our collection, we found that impaired GAPDH presence in the surface and supernatant of GBS was associated with a lower level of bacterial lysis. We also found that following GBS lysis, GAPDH can associate to the surface of many living bacteria. Finally, we provide evidence for a novel function of the secreted GAPDH as an inducer of apoptosis of murine macrophages.

Molecular phylogeny and evolution of parabasalia with improved taxon sampling and new protein markers of actin and elongation factor-1α

Background

Inferring the evolutionary history of phylogenetically isolated, deep-branching groups of taxa—in particular determining the root—is often extraordinarily difficult because their close relatives are unavailable as suitable outgroups. One of these taxonomic groups is the phylum Parabasalia, which comprises morphologically diverse species of flagellated protists of ecological, medical, and evolutionary significance. Indeed, previous molecular phylogenetic analyses of members of this phylum have yielded conflicting and possibly erroneous inferences. Furthermore, many species of Parabasalia are symbionts in the gut of termites and cockroaches or parasites and therefore formidably difficult to cultivate, rendering available data insufficient. Increasing the numbers of examined taxa and informative characters (e.g., genes) is likely to produce more reliable inferences.

Principal Findings

Actin and elongation factor-1α genes were identified newly from 22 species of termite-gut symbionts through careful manipulations and seven cultured species, which covered major lineages of Parabasalia. Their protein sequences were concatenated and analyzed with sequences of previously and newly identified glyceraldehyde-3-phosphate dehydrogenase and the small-subunit rRNA gene. This concatenated dataset provided more robust phylogenetic relationships among major groups of Parabasalia and a more plausible new root position than those previously reported.

Conclusions/Significance

We conclude that increasing the number of sampled taxa as well as the addition of new sequences greatly improves the accuracy and robustness of the phylogenetic inference. A morphologically simple cell is likely the ancient form in Parabasalia as opposed to a cell with elaborate flagellar and cytoskeletal structures, which was defined as most basal in previous inferences. Nevertheless, the evolution of Parabasalia is complex owing to several independent multiplication and simplification events in these structures. Therefore, systematics based solely on morphology does not reflect the evolutionary history of parabasalids.

Antisense suppression of the small chloroplast protein CP12 in tobacco: a transcriptional viewpoint

The chloroplast protein CP12 forms a multi-enzyme complex with the Calvin-Benson cycle enzymes phosphoribulokinase (PRK) and NADP-glyceraldehyde-3-phosphate dehydrogenase (GAPDH). PRK and GAPDH are inactivated when present in this complex, a process shown in vitro to be dependent upon oxidized CP12. Recently we reported on the importance of CP12 in vivo to higher plant metabolism using antisense suppression of CP12 in tobacco (Nicotiana tabacum). Our results indicated that while only minor changes in photosynthetic carbon fixation and in PRK and GAPDH activities were observed, striking changes in growth rates and morphology were seen. In this article we present data on the transcriptional changes observed in one of the antisense lines and we discuss the major findings in light of the metabolic phenotype described.