Over-expression of GAPDH induces apoptosis in COS-7 cells transfected with cloned GAPDH cDNAs

Selection of stable reference genes for qPCR expression of Colletotrichum lindemuthianum, the bean anthracnose pathogen

Phaseolus vulgaris L., commonly known as the common bean, is a highly nutritious crop often called the "poor man's meat". However, it is susceptible to various diseases throughout the cropping season, with anthracnose caused by Colletotrichum lindemuthianum being a significant threat that leads to substantial losses. There is still a lack of understanding about the molecular basis of C. lindemuthianum pathogenicity. The first step in understanding this is to identify pathogenicity genes that express more during infection of common beans. A reverse transcription quantitative real-time PCR (qPCR) method can be used for virulence gene expression. However, this approach requires selecting appropriate reference genes to normalize relative gene expression data. Currently, there is no reference gene available for C. lindemuthianum. In this study, we selected eight candidate reference genes from the available genome of C. lindemuthianum to bridge the gap. These genes were ACT (Actin), β-tub (β-tubulin), EF (Elongation Factor), Cyt C (Cytochrome C), His H3 (Histone H3), CHS1 (Chitin synthetase), GAPDH (Glyceraldehyde-3-phosphate dehydrogenase) and abfA (Alpha-l-Arabinofuranosidase A). The primers for these candidate reference genes were able to amplify cDNA only from the pathogen, demonstrating their specificity. The qPCR efficiency of the primers ranged from 80% to 103%. We analyzed the stability of gene expression in C. lindemuthianum by exposing the mycelium to nine different stress conditions. We employed algorithms, such as GeNorm, NormFinder, BestKeeper, and RefFinder tools, to identify the most stable gene. The analysis using these tools revealed that EF, GAPDH, and β-tub most stable genes, while ACT and CHS1 showed relatively low expression stability. A large number of potential effector genes have been identified through bioinformatics analysis in C. lindemuthianum. The stable genes for qPCR (EF and GAPDH) discovered in this study will aid the scientific community in determining the relative expression of C. lindemuthianum effector genes.

Genetic screening for anticancer genes highlights FBLN5 as a synthetic lethal partner of MYC

BACKGROUND

When ectopically overexpressed, anticancer genes, such as TRAIL, PAR4 and ORCTL3, specifically destroy tumour cells without harming untransformed cells. Anticancer genes can not only serve as powerful tumour specific therapy tools but studying their mode of action can reveal mechanisms underlying the neoplastic transformation, sustenance and spread.

METHODS

Anticancer gene discovery is normally accidental. Here we describe a systematic, gain of function, forward genetic screen in mammalian cells to isolate novel anticancer genes of human origin. Continuing with over 30,000 transcripts from our previous study, 377 cell death inducing genes were subjected to screening. FBLN5 was chosen, as a proof of principle, for mechanistic gene expression profiling, comparison pathways analyses and functional studies.

RESULTS

Sixteen novel anticancer genes were isolated; these included non-coding RNAs, protein-coding genes and novel transcripts, such as ZNF436-AS1, SMLR1, TMEFF2, LINC01529, HYAL2, NEIL2, FBLN5, YPEL4 and PHKA2-processed transcript. FBLN5 selectively caused inhibition of MYC in COS-7 (transformed) cells but not in CV-1 (normal) cells. MYC was identified as synthetic lethality partner of FBLN5 where MYC transformed CV-1 cells experienced cell death upon FBLN5 transfection, whereas FBLN5 lost cell death induction in MCF-7 cells upon MYC knockdown.

CONCLUSIONS

Sixteen novel anticancer genes are present in human genome including FBLN5. MYC is a synthetic lethality partner of FBLN5. Video Abstract.

Current Practices for Reference Gene Selection in RT-qPCR of Aspergillus: Outlook and Recommendations for the Future

Aspergillus is a genus of filamentous fungi with vast geographic and ecological distributions. Species within this genus are clinically, agriculturally and biotechnologically relevant, leading to increasing interest in elucidating gene expression dynamics of key metabolic and physiological processes. Reverse-transcription quantitative Polymerase Chain Reaction (RT-qPCR) is a sensitive and specific method of quantifying gene expression. A crucial step for comparing RT-qPCR results between strains and experimental conditions is normalisation to experimentally validated reference gene(s). In this review, we provide a critical analysis of current reference gene selection and validation practices for RT-qPCR gene expression analyses of Aspergillus. Of 90 primary research articles obtained through our PubMed query, 17 experimentally validated the reference gene(s) used. Twenty reference genes were used across the 90 studies, with beta-tubulin being the most used reference gene, followed by actin, 18S rRNA and glyceraldehyde 3-phosphate dehydrogenase. Sixteen of the 90 studies used multiple reference genes for normalisation. Failing to experimentally validate the stability of reference genes can lead to conflicting results, as was the case for four studies. Overall, our review highlights the need to experimentally validate reference genes in RT-qPCR studies of Aspergillus.

Associations of Genetic Variation in Glyceraldehyde 3-Phosphate Dehydrogenase Gene with Noise-Induced Hearing Loss in a Chinese Population: A Case-Control Study

Objective: The purpose of this paper was to clarify the association between genetic variation in the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene and the risk of noise-induced hearing loss (NIHL). Methods: A case-control study (633 cases and 625 controls) was conducted in this study. Logistic regression was used to analyze the relationships between environmental and individual factors and NIHL. Gene expression levels were compared among each GAPDH rs6489721 genotype and between the case and control groups based on real-time fluorescence quantitative Polymerase Chain Reaction (PCR). Results: The T allele of GADPH rs6489721 was significantly associated with NIHL (odds ratio (OR) = 1.262, 95% confidence interval (CI) (1.066, 1.493), p = 0.006) and showed strong associations in the codominant and dominant models (TT vs. CC: OR = 1.586, 95% CI (1.131, 2.225), p = 0.008; TT vs. TC/CC: OR = 1.391, 95% CI (1.073, 1.804), p = 0.013). The expression level of the TT genotype was significantly higher than that of the CC genotype (p = 0.012), and the expression of the case group was also higher than that of the control group (p = 0.013). Conclusions: The homozygous risk allele (TT) of rs6489721 was associated with an enhanced GAPDH expression, resulting in the development of NIHL in a Chinese population.

Adhesion molecules facilitate host-pathogen interaction & mediate Mycobacterium tuberculosis pathogenesis

Most of the microorganisms display adhesion molecules on their surface which help them to bind and interact with the host cell during infection. Adhesion molecules help mycobacteria to colonize and invade immune system of the host, and also trigger immune response explicated by the host against the infection. Hence, understanding the signalling pathways illustrated by these molecules to enhance our knowledge on mycobacterial survival and persistence inside the host cell is required. Hence, this review was focussed on the role of adhesion molecules and their receptor molecules. The various mechanisms adopted by adhesion molecules to bind with the specific receptors on the host cell and their role in invasion and persistence of mycobacterium inside the host cell are explained.

Effects of sorbitol and lactate on erythropoietin production in HepG2 cells

Promotion of erythropoietin (EPO) production is important for erythropoiesis as well as cell viability. The most effective inducing factor for EPO production is hypoxia. Hypoxia inducible factor (HIF), a regulator of EPO production, is increased under hypoxic conditions and is also affected by various regulators such as sirtuin1 (SIRT1). SIRT1 is regulated by the cytoplasmic redox state, which is thought to affect EPO production. Therefore, we investigated the effects of sorbitol and lactic acid, which serve as substrates for cellular respiration and bring cells into a reduced state, on EPO production in HepG2 cells. The addition of low-concentration sorbitol to HepG2 cells produced a mildly reduced state similar to that of hypoxia and increased NAD⁺, SIRT1, and HIF-α, and EPO mRNA expression. On the other hand, lactate suppressed EPO mRNA expression at all concentrations. Inhibition of lactate production from pyruvate abolished the effect of low sorbitol concentrations on EPO mRNA expression. When low-concentration sorbitol and a reducing agent were administered simultaneously, the effect of increasing EPO mRNA expression disappeared. It was suggested that SIRT1 and EPO production increased under conditions where lactate production was not suppressed, even under mildly reduced conditions similar to hypoxia.

Non-Toxic and Ultra-Small Biosilver Nanoclusters Trigger Apoptotic Cell Death in Fluconazole-Resistant Candida albicans via Ras Signaling

Silver-based nanostructures are suitable for many biomedical applications, but to be useful therapeutic agents, the high toxicity of these nanomaterials must be eliminated. Here, we biosynthesize nontoxic and ultra-small silver nanoclusters (rsAg@NCs) using metabolites of usnioid lichen (a symbiotic association of algae and fungi) that exhibit excellent antimicrobial activity against fluconazole (FCZ)-resistant Candida albicans that is many times higher than chemically synthesized silver nanoparticles (AgNPs) and FCZ. The rsAg@NCs trigger apoptosis via reactive oxygen species accumulation that leads to the loss of mitochondrial membrane potential, DNA fragmentation, chromosomal condensation, and the activation of metacaspases. The proteomic analysis clearly demonstrates that rsAg@NCs exposure significantly alters protein expression. Most remarkable among the down-regulated proteins are those related to glycolysis, metabolism, free radical scavenging, anti-apoptosis, and mitochondrial function. In contrast, proteins involved in plasma membrane function, oxidative stress, cell death, and apoptosis were upregulated. Eventually, we also established that the apoptosis-inducing potential of rsAg@NCs is due to the activation of Ras signaling, which confirms their application in combating FCZ-resistant C. albicans infections.

GAPDH rs1136666 SNP indicates a high risk of Parkinson's disease

BACKGROUND

Development of Parkinson's disease (PD) is attributed to both genetic and environmental factors. Furthermore,GAPDH may play a key role in the development of neurodegenerative disease. Examination of genetic polymorphism in patients with sporadic PD will help uncover the mechanisms of PD pathogenesis and provide new insights into the treatment of PD.

METHODS AND RESULTS

The SNaPshot method was applied to determine the gene sequences in 265 patients with idiopathic PD and 269 control cases (sex- and age-matched). The rs1136666 polymorphism of GAPDH was determined to be closely associated with PD. Subsequently, the CC genotype of the rs1136666 fragment was transfected into SH-SY5Y cells via a plasmid. The genetic expression of rs1136666 CC could induce SH-SY5Y cell injury and apoptosis via regulation of the oxidant-antioxidant and apoptosis-antiapoptosis balance. rs1136666 CC of the GAPDH had a pro-apoptotic effect similar to that of rotenone, and combination of the rs1136666 CC genetic variation and the rotenone neurotoxic effect could aggravate oxidative stress, cell injury, and apoptosis better than either single treatment alone.

CONCLUSION

This study confirmed that the rs1136666 CC allele of theGAPDH increased the risk of PD, particularly in older male patients.

Proteomic analysis of apoptosis induction by lariciresinol in human HepG2 cells

Lariciresinol (LA) is a traditional Chinese medicine possessing anticancer activity, but its mechanism of action remains unclear. The present study explored the effects of LA on human HepG2 cells and the underlying mechanism. Our data indicated that LA inhibited cell proliferation and induced cell cycle arrest in S phase, subsequently resulting in apoptosis in HepG2 cells. Using a proteomics approach, eight differentially expressed proteins were identified. Among them, three proteins, glyceraldehyde-3-phosphate, UDP-glucose 4-epimerase, and annexin A1, were upregulated, while the other five proteins, heat shock protein 27, haptoglobin, tropomodulin-2, tubulin alpha-1A chain, and brain acid soluble protein 1, were downregulated; all of these proteins are involved in cell proliferation, metabolism, cytoskeletal organization, and movement. Network analysis of these proteins suggested that the ubiquitin-conjugating enzyme (UBC) plays an important role in the mechanism of LA. Western blotting confirmed downregulation of heat shock protein 27 and upregulation of ubiquitin and UBC expression levels in LA-treated cells, consistent with the results of two-dimensional electrophoresis and a STRING software-based analysis. Overall, LA is a multi-target compound with anti-cancer effects potentially related to the ubiquitin-proteasome pathway. This study will increase our understanding of the anticancer mechanisms of LA.

Developmental toxicity of hexachloronaphthalene in Wistar rats. A role of CYP1A1 expression

Hexachloronaphthalene (HxCN) is one of the most toxic congeners of polychlorinated naphthalenes (PCNs). This study assesses the prenatal toxicity of HxCN after daily administration at doses of 0.1-1.0mg/kg b.w. to pregnant Wistar rats during organogenesis. We evaluated also the expression of CYP1A1 mRNA and protein in the livers of dams and fetuses, as well as the placenta. The results indicate that 0.3mg/kg b.w. was the lowest HxCN toxic dose for dams (LOAEL) while a dose of 0.1mg/kg b.w. was sufficient to impair the intrauterine development of embryos/fetuses without maternal toxicity. Regardless of the applied dose, HxCN generated embryotoxic effects. Dose-dependent fetotoxic effects were associated with HxCN exposure. HxCN was found to be a strong inducer of maternal and fetal CYP1A1. Expression of CYP1A1 mRNA in the placenta appears to be the most sensitive marker of HxCN exposure.

The effect of hemin-induced oxidative stress on erythropoietin production in HepG2 cells

Erythropoietin (EPO) and iron are both indispensable hematopoietic factors and are often studied in humans and rodents. Iron activates prolyl hydroxylases (PHDs) and promotes the degradation of the α-subunit of hypoxia inducible factor (HIF), which regulates EPO production. Iron also causes oxidative stress. Oxidative stress leads to alterations in the levels of multiple factors that regulate HIF and EPO production. It is thought that iron influences EPO production by altering two pathways, namely PHDs activity and oxidative stress. We studied the differential effect of varying concentrations of hemin, an iron-containing porphyrin, on EPO production in HepG2 cells. Hemin at 100 µM reduced EPO mRNA expression. The hemin-induced reduction of EPO mRNA levels was attenuated at concentrations greater than 200 µM and EPO production increased in the presence of 500 µM hemin. In comparison, protoporphyrin IX, iron-free hemin did not influence EPO mRNA expression. Additionally, malondialdehyde (MDA) concentrations and superoxide dismutase (SOD) activity significantly increased with 300 µM hemin. Importantly, the antioxidant tempol inhibited the hemin-induced (500 µM) increase in EPO mRNA levels. In conclusion, these results suggest that restraint of EPO production by hemin was offset by the promotion of EPO production by hemin-induced oxidative stress at hemin concentrations greater than 300 µM.

Kinetic and mechanistic characterization of the glyceraldehyde 3-phosphate dehydrogenase from Mycobacterium tuberculosis

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a glycolytic protein responsible for the conversion of glyceraldehyde 3-phosphate (G3P), inorganic phosphate and nicotinamide adenine dinucleotide (NAD(+)) to 1,3-bisphosphoglycerate (1,3-BPG) and the reduced form of nicotinamide adenine dinucleotide (NADH). Here we report the characterization of GAPDH from Mycobacterium tuberculosis (Mtb). This enzyme exhibits a kinetic mechanism in which first NAD(+), then G3P bind to the active site resulting in the formation of a covalently bound thiohemiacetal intermediate. After oxidation of the thiohemiacetal and subsequent nucleotide exchange (NADH off, NAD(+) on), the binding of inorganic phosphate and phosphorolysis yields the product 1,3-BPG. Mutagenesis and iodoacetamide (IAM) inactivation studies reveal the conserved C158 to be responsible for nucleophilic catalysis and that the conserved H185 to act as a catalytic base. Primary, solvent and multiple kinetic isotope effects revealed that the first half-reaction is rate limiting and utilizes a step-wise mechanism for thiohemiacetal oxidation via a transient alkoxide to promote hydride transfer and thioester formation.

Characterizing cell-cell interactions induced spatial organization of cell phenotypes: application to density-dependent protein nucleocytoplasmic distribution

Cell-cell interactions play an important role in spatial organization (pattern formation) during the development of multicellular organisms. An understanding of these biological roles requires identifying cell phenotypes that are regulated by cell-cell interactions and characterizing the spatial organizations of the phenotypes. However, conventional methods for assaying cell-cell interactions are mainly applicable at a cell population level. These measures are incapable of elucidating the spatial organizations of the phenotypes, resulting in an incomplete view of cell-cell interactions. To overcome this issue, we developed an automated image-based method to investigate cell-cell interactions based on spatial localizations of cells. We demonstrated this method in cultured cells using cell density-dependent nucleocytoplasmic distribution of β-catenin and aryl hydrocarbon receptor as the phenotype. This novel method was validated by comparing with a conventional population-based method, and proved to be more sensitive and reliable. The application of the method characterized how the phenotypes were spatially organized in a population of cultured cells. We further showed that the spatial organization was governed by cell density and was protein-specific. This automated method is very simple, and will be applicable to study cell-cell interactions in different systems from prokaryotic colonies to multicellular organisms. We envision that the ability to extract and interpret how cell-cell interactions determine the spatial organization of a cell phenotype will provide new insights into biology that may be missed by traditional population-averaged studies.

Nuclear translocation and accumulation of glyceraldehyde-3-phosphate dehydrogenase involved in diclazuril-induced apoptosis in Eimeria tenella (E. tenella)

In mammalian cells, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) has recently been shown to be implicated in numerous apoptotic paradigms, especially in neuronal apoptosis, and has been demonstrated to play a vital role in some neurodegenerative disorders. However, this phenomenon has not been reported in protists. In the present study, we report for the first time that such a mechanism is involved in diclazuril-induced apoptosis in Eimeria tenella (E. tenella). We found that upon treatment of parasites with diclazuril, the expression levels of GAPDH transcript and protein were significantly increased in second-generation merozoites. Then, we examined the subcellular localization of GAPDH by fluorescence microscopy and Western blot analysis. The results show that a considerable amount of GAPDH protein appeared in the nucleus within diclazuril-treated second-generation merozoites; in contrast, the control group had very low levels of GAPDH in the nucleus. The glycolytic activity of GAPDH was kinetically analyzed in different subcellular fractions. A substantial decrease (48.5%) in glycolytic activity of GAPDH in the nucleus was displayed. Moreover, the activities of caspases-3, -9, and −8 were measured in cell extracts using specific caspase substrates. The data show significant increases in caspase-3 and caspase-9 activities in the diclazuril-treated group.

Glyceraldehyde-3-phosphate dehydrogenase interacts with proapoptotic kinase mst1 to promote cardiomyocyte apoptosis

Mammalian sterile 20-like kinase 1 (Mst1) is a critical component of the Hippo signaling pathway, which regulates a variety of biological processes ranging from cell contact inhibition, organ size control, apoptosis and tumor suppression in mammals. Mst1 plays essential roles in the heart disease since its activation causes cardiomyocyte apoptosis and dilated cardiomyopathy. However, the mechanism underlying Mst1 activation in the heart remains unknown. In a yeast two-hybrid screen of a human heart cDNA library with Mst1 as bait, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was identified as an Mst1-interacting protein. The interaction of GAPDH with Mst1 was confirmed by co-immunoprecipitation in both co-transfected HEK293 cells and mouse heart homogenates, in which GAPDH interacted with the kinase domain of Mst1, whereas the C-terminal catalytic domain of GAPDH mediated its interaction with Mst1. Moreover, interaction of Mst1 with GAPDH caused a robust phosphorylation of GAPDH and markedly increased the Mst1 activity in cells. Chelerythrine, a potent inducer of apoptosis, substantially increased the nuclear translocation and interaction of GAPDH and Mst1 in cardiomyocytes. Overexpression of GAPDH significantly augmented the Mst1 mediated apoptosis, whereas knockdown of GAPDH markedly attenuated the Mst1 activation and cardiomyocyte apoptosis in response to either chelerythrine or hypoxia/reoxygenation. These findings reveal a novel function of GAPDH in Mst1 activation and cardiomyocyte apoptosis and suggest that disruption of GAPDH interaction with Mst1 may prevent apoptosis related heart diseases such as heart failure and ischemic heart disease.

GAPDH: a common enzyme with uncommon functions

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has long been recognized as an important enzyme for energy metabolism and the production of ATP and pyruvate through anaerobic glycolysis in the cytoplasm. Recent studies have shown that GAPDH has multiple functions independent of its role in energy metabolism. Although increased GAPDH gene expression and enzymatic function is associated with cell proliferation and tumourigenesis, conditions such as oxidative stress impair GAPDH catalytic activity and lead to cellular aging and apoptosis. The mechanism(s) underlying the effects of GAPDH on cellular proliferation remains unclear, yet much evidence has been accrued that demonstrates a variety of interacting partners for GAPDH, including proteins, various RNA species and telomeric DNA. The present mini review summarizes recent findings relating to the extraglycolytic functions of GAPDH and highlights the significant role this enzyme plays in regulating both cell survival and apoptotic death.

Effect of Trypanosoma brucei brucei on erythropoiesis in infected rats

Anemia generated from African trypanosome infection is considered an important symptom in humans and in domestic animals. In order to recover from anemia, the process of erythropoiesis is essential. Erythropoiesis is affected by erythropoietin (EPO), an erythropoietic hormone, supplying iron and inflammatory and proinflammatory cytokines. However, the role of these factors in erythropoiesis during African trypanosome infection remains unclear. In the present study, we analyze how erythropoiesis is altered in anemic Trypanosoma brucei brucei (interleukin-tat 1.4 strain [ILS])-infected rats. We report that the packed cell volume (PCV) of blood from ILS-infected rats was significantly lower 4 days after infection, whereas the number of reticulocytes, as an index of erythropoiesis, did not increase. The level of EPO mRNA in ILS-infected rats did not increase from the third day to the sixth day after infection, the same time that the PCV decreased. Kidney cells of uninfected rats cultured with ILS trypanosome strain for 8 hr in vitro decreased EPO mRNA levels. Treatment of both ILS and cobalt chloride mimicked hypoxia, which restrained the EPO-production-promoting effect of the cobalt. Messenger RNA levels of β-globin and transferrin receptor, as markers of erythropoiesis in the bone marrow, also decreased in ILS-infected rats. Levels of hepcidin mRNA, which controls the supply of iron to the marrow in liver, were increased in ILS-infected rats; however, the concentration of serum iron did not change. Furthermore, mRNA levels of interleukin-12, interferon-γ, tumor necrosis factor-α, and macrophage migration inhibitory factor in the spleen, factors that have the potential to restrain erythropoiesis in bone marrow, were elevated in the ILS-infected rats. These results suggest that ILS infection in rats affect erythropoiesis, which responds by decreasing EPO production and restraining its function in the bone marrow.

Differential effects of Trypanosoma brucei gambiense and Trypanosoma brucei brucei on rat macrophages

Mammalian immune responses to Trypanosoma brucei infection are important to control of the disease. In rats infected with T. brucei gambiense (Wellcome strain; WS) or T. brucei brucei (interleukin-tat 1.4 strain [ILS]), a marked increase in the number of macrophages in the spleen can be observed. However, the functional repercussions related to this expansion are not known. To help uncover the functional significance of macrophages in the context of trypanosome infection, we determined the mRNA levels of genes associated with an increase in macrophage number or macrophage function in WS- and ILS-infected rats and in cultured cells. Specifically, we assayed mRNA levels for macrophage colony stimulating factor (M-CSF), granulocyte macrophage colony stimulating factor (GM-CSF), and macrophage migration inhibitory factor (MIF). Upregulation of GM-CSF and MIF mRNA levels was robust in comparison with changes in M-CSF levels in ILS-infected rats. By contrast, upregulation of M-CSF was more robust in WS-infected rats. The phagocytic activity in macrophages harvested from ILS-infected rat spleens, but not WS-infected spleens, was higher than that in macrophages from uninfected rats. These results suggest that macrophages of WS-infected rats change to an immunosuppressive type. However, when WS or ILS is cocultured with spleen macrophages or HS-P cells, a cell line of rat macrophage origin, M-CSF is upregulated relative to GM-CSF and MIF in both cell types. Anemia occurs in ILS-, but not WS-infected, rats. Treatment of spleen macrophages or HS-P cells cocultured with ILS with cobalt chloride, which mimics the effects of anemia-induced hypoxia, led to downregulation of M-CSF mRNA levels, upregulation of GM-CSF and MIF, and an increase in phagocytic activity. However, the effect of cobalt chloride on spleen macrophages and HS-P cells cocultured with WS was restricted. These results suggest that anemia-induced hypoxia in ILS-infected rats stimulates the immune system and activates macrophages.

Seasonal effects on gene expression, cleavage timing, and developmental competence of bovine preimplantation embryos

We examined the association between season and expression of genes involved in early embryonic development with an emphasis on cleavage rate and timing of the first embryonic cleavage. In Exp. 1, oocytes were aspirated during the cold (Dec–Apr) and hot (May–Nov) seasons. Matured oocytes were chemically activated and culturedin vitro. The developmental peak to the two- and four-cell stages occurred earlier, with a higher proportion of first-cleaved embryos, during the cold season relative to the hot season (P<0.01). In Exp. 2, a time-lapse system was employed to characterize the delayed cleavage noted for the hot season. Cleavage to the two-cell stage occurred in two distinct waves: early cleavage occurred between 18 and 25 h post activation, and late cleavage occurred between 27 and 40 h post activation. In Exp. 3, oocytes were aspirated during the cold and hot seasons, maturedin vitro, fertilized, and cultured for 8 days. In each season, early- and late-cleaved two-cell stage embryos were collected. Total RNA was isolated, and semi-quantitative and real-time PCRs were carried out with primers forGDF9,POU5F1, andGAPDHusing18S rRNAas the reference gene. In both seasons, the expression of all examined genes was higher (P<0.05) in early- versus late-cleaved embryos.POU5F1expression was higher (P<0.05) in early-cleaved embryos developed in the cold season versus the hot season counterparts. The findings suggest a deleterious seasonal effect on oocyte developmental competence with delayed cleavage and variation in gene expression.

Effect of polyamine-deficient chow on Trypanosoma brucei brucei infection in rats

Polyamines are essential for proliferation of Trypanosoma brucei brucei, and feeding rats polyamine-deficient chow (PDC) decreases their blood polyamine concentrations. Proliferation of T. b. brucei (IL-tat 1.4 strain) (IL) is not restrained within PDC-fed rats. However, symptoms of IL-infected rats such as anemia decrease by PDC feeding. We reported cytokine and nitric oxide (NO) production of T. b. gambiense (Wellcome strain [WS])-infected rats were affected by PDC feeding, and WS proliferation was restrained. Therefore, we investigated whether the change in production of cytokines and NO by PDC feeding affects IL proliferation and decreases symptoms in vivo. In IL-infected PDC-fed rats, NO, interleukin (IL)-12, and tumor necrosis factor-alpha production increased while interferon-gamma and IL-10 decreased compared to normal chow-fed rats. IL proliferation was restrained by NO production when it was co-cultured with spleen cells harvested from uninfected rats. In contrast, IL proliferation in infected rats was not changed by PDC feeding, although NO production was increased. The results suggest that changes in cytokines and NO production in IL-infected rats by PDC feeding have little influence on IL proliferation. However, they may serve to decrease symptoms.

A metabolomic and multivariate statistical process to assess the effects of genotoxins in Saccharomyces cerevisiae

There is an increased need to develop robust cellular model systems which could replace or reduce the need for animals in toxicological testing. Current in vitro strategies for genotoxicity testing suffer from a high irrelevant positive rate, requiring the need for the development of new in vitro tools. Saccharomyces cerevisiae is used widely to study DNA damage and repair, and a high-throughput green fluorescent protein based assay has been developed to detect genotoxic-induced DNA damage. In this study a combined high resolution (1)H NMR spectroscopy and gas chromatography mass spectrometry based metabolomic approach has been used to monitor and distinguish different genotoxic compounds from other types of toxic lesion using the multivariate classification tool partial least squares-discriminate analysis (PLS-DA). The metabolic profiles of extracts of yeast (W303alpha strain) readily distinguished the individual toxins from control cells across 22 different treatments. In addition, these metabolic profiles also demonstrated dose and time responses for selected compounds (methyl methane sulfonate and nocodazole). Finally, predictive models were built for distinguishing the genotoxic carcinogens from the control group according to the metabolic profile of the cell culture media.

Proteomic screen in the simple metazoan Hydra identifies 14-3-3 binding proteins implicated in cellular metabolism, cytoskeletal organisation and Ca2+ signalling

Background

14-3-3 proteins have been implicated in many signalling mechanisms due to their interaction with Ser/Thr phosphorylated target proteins. They are evolutionarily well conserved in eukaryotic organisms from single celled protozoans and unicellular algae to plants and humans. A diverse array of target proteins has been found in higher plants and in human cell lines including proteins involved in cellular metabolism, apoptosis, cytoskeletal organisation, secretion and Ca²⁺ signalling.

Results

We found that the simple metazoan Hydra has four 14-3-3 isoforms. In order to investigate whether the diversity of 14-3-3 target proteins is also conserved over the whole animal kingdom we isolated 14-3-3 binding proteins from Hydra vulgaris using a 14-3-3-affinity column. We identified 23 proteins that covered most of the above-mentioned groups. We also isolated several novel 14-3-3 binding proteins and the Hydra specific secreted fascin-domain-containing protein PPOD. In addition, we demonstrated that one of the 14-3-3 isoforms, 14-3-3 HyA, interacts with one Hydra-Bcl-2 like protein in vitro.

Conclusion

Our results indicate that 14-3-3 proteins have been ubiquitous signalling components since the start of metazoan evolution. We also discuss the possibility that they are involved in the regulation of cell numbers in response to food supply in Hydra.

Regulation of oncogenic transcription factor hTAF(II)68-TEC activity by human glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

Tumour-specific chromosomal rearrangements are known to create chimaeric products with the ability to generate many human cancers. hTAF(II)68-TEC (where hTAF(II)68 is human TATA-binding protein-associated factor II 68 and TEC is translocated in extraskeletal chondrosarcoma) is such a fusion product, resulting from a t(9;17) chromosomal translocation found in extraskeletal myxoid chondrosarcomas, where the hTAF(II)68 NTD (N-terminal domain) is fused to TEC protein. To identify proteins that control hTAF(II)68-TEC function, we used affinity chromatography on immobilized hTAF(II)68 (NTD) and MALDI-TOF (matrix-assisted laser-desorption ionization-time-of-flight) MS and isolated a novel hTAF(II)68-TEC-interacting protein, GAPDH (glyceraldehyde-3-phosphate dehydrogenase). GAPDH is a glycolytic enzyme that is also involved in the early steps of apoptosis, nuclear tRNA export, DNA replication, DNA repair and transcription. hTAF(II)68-TEC and GAPDH were co-immunoprecipitated from cell extracts, and glutathione S-transferase pull-down assays revealed that the C-terminus of hTAF(II)68 (NTD) was required for interaction with GAPDH. In addition, three independent regions of GAPDH (amino acids 1-66, 67-160 and 160-248) were involved in binding to hTAF(II)68 (NTD). hTAF(II)68-TEC-dependent transcription was enhanced by GAPDH, but not by a GAPDH mutant defective in hTAF(II)68-TEC binding. Moreover, a fusion of GAPDH with the GAL4 DNA-binding domain increased the promoter activity of a reporter containing GAL4 DNA-binding sites, demonstrating the presence of a transactivation domain(s) in GAPDH. The results of the present study suggest that the transactivation potential of the hTAF(II)68-TEC oncogene product is positively modulated by GAPDH.

Glyceraldehyde-3-phosphate dehydrogenase exerts different biologic activities in apoptotic and proliferating hepatocytes according to its subcellular localization

Recent evidences indicate new roles for the glycolytic protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in essential mammalian cell processes, such as apoptosis and proliferation. To clarify the involvement of this protein in growth and programmed cell death in the liver, cell models of hepatocytes in culture were used to study GAPDH expression, localization and enzymatic activity in hepatocyte proliferation and apoptosis. GAPDH expression in cell compartments was studied by Western blot. Nuclear expression of GAPDH increased in apoptosis, and cytoplasmic expression was elevated in apoptosis and proliferation. Subcellular localization was determined by GAPDH immunostaining and confocal microscopic analysis. Quiescent and proliferating hepatocytes showed cytoplasmic GAPDH, while apoptotic cells showed cytoplasmic but also some nuclear staining. The glycolytic activity of GAPDH was studied in nuclear and cytoplasmic cell compartments. GAPDH enzymatic activity increased in the nucleus of apoptotic cells and in cytoplasms of apoptotic and proliferating hepatocytes. Our observations indicate that during hepatocyte apoptosis GAPDH translocates to the nucleus, maintaining in part its dehydrogenase activity, and suggest that this translocation may play a role in programmed hepatocyte death. GAPDH over-expression and the increased enzymatic activity in proliferating cells, with preservation of its cytoplasmic localization, would occur in response to the elevated energy requirements of dividing hepatocytes. In conclusion, GAPDH plays different roles or biological activities in proliferating and apoptotic hepatocytes, according to its subcellular localization.

GAPDH, a novel regulator of the pro-apoptotic mitochondrial membrane permeabilization

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a pleiotropic enzyme that is overexpressed in apoptosis and in several human chronic pathologies. Here, we report that the protein accumulates in mitochondria during apoptosis, and induces the pro-apoptotic mitochondrial membrane permeabilization, a decisive event of the intrinsic pathway of apoptosis. GAPDH was localized by immunogold labeling and identified by matrix-assisted laser desorption/ionization-time of flight and nano liquid chromatography mass spectroscopy/mass spectroscopy in the mitochondrion of various tissues and origins. In isolated mitochondria, GAPDH can be imported and interact with the voltage-dependent anion channel (VDAC1), but not the adenine nucleotide translocase (ANT). The protein mediates a cyclosporin A-inhibitable permeability transition, characterized by a loss of the inner transmembrane potential, matrix swelling, permeabilization of the inner mitochondrial membrane and the release of two pro-apoptotic proteins, cytochrome c and apoptosis-inducing factor (AIF). This novel function of GAPDH might have implications for the understanding of mitochondrial biology, oncogenesis and apoptosis.

Glycolysis inhibition for anticancer treatment

Most cancer cells exhibit increased glycolysis and use this metabolic pathway for generation of ATP as a main source of their energy supply. This phenomenon is known as the Warburg effect and is considered as one of the most fundamental metabolic alterations during malignant transformation. In recent years, there are significant progresses in our understanding of the underlying mechanisms and the potential therapeutic implications. Biochemical and molecular studies suggest several possible mechanisms by which this metabolic alteration may evolve during cancer development. These mechanisms include mitochondrial defects and malfunction, adaptation to hypoxic tumor microenvironment, oncogenic signaling, and abnormal expression of metabolic enzymes. Importantly, the increased dependence of cancer cells on glycolytic pathway for ATP generation provides a biochemical basis for the design of therapeutic strategies to preferentially kill cancer cells by pharmacological inhibition of glycolysis. Several small molecules have emerged that exhibit promising anticancer activity in vitro and in vivo, as single agent or in combination with other therapeutic modalities. The glycolytic inhibitors are particularly effective against cancer cells with mitochondrial defects or under hypoxic conditions, which are frequently associated with cellular resistance to conventional anticancer drugs and radiation therapy. Because increased aerobic glycolysis is commonly seen in a wide spectrum of human cancers and hypoxia is present in most tumor microenvironment, development of novel glycolytic inhibitors as a new class of anticancer agents is likely to have broad therapeutic applications.

Mitochondria-associated hexokinases play a role in the control of programmed cell death in Nicotiana benthamiana

Recent findings suggest a pivotal role for mitochondria-associated hexokinase in the regulation of apoptosis in animal cells. In this study, virus-induced gene silencing (VIGS) of a hexokinase-encoding Hxk1 caused necrotic lesions on leaves, abnormal leaf morphology, and retarded plant growth in Nicotiana benthamiana. Hxk1 was associated with the mitochondria, and this association required the N-terminal membrane anchor. VIGS of Hxk1 reduced the cellular glucose-phosphorylating activity to approximately 31% of control levels without changing the fructose-phosphorylating activity and did not alter hexose phosphate content severely. The affected cells showed programmed cell death (PCD) morphological markers, including nuclear condensation and DNA fragmentation. Similar to animal cell apoptosis, cytochrome c was released into the cytosol and caspase-9- and caspase-3-like proteolytic activities were strongly induced. Furthermore, based on flow cytometry, Arabidopsis thaliana plants overexpressing Arabidopsis HXK1 and HXK2, both of which are predominantly associated with mitochondria, exhibited enhanced resistance to H(2)O(2)- and alpha-picolinic acid-induced PCD. Finally, the addition of recombinant Hxk1 to mitochondria-enriched fractions prevented H(2)O(2)/clotrimazole-induced cytochrome c release and loss of mitochondrial membrane potential. Together, these results show that hexokinase critically regulates the execution of PCD in plant cells, suggesting a link between glucose metabolism and apoptosis.

Adjudin-mediated junction restructuring in the seminiferous epithelium leads to displacement of soluble guanylate cyclase from adherens junctions

A plethora of evidence supports the role of cyclic nucleotides in junction restructuring. For instance, studies have shown cGMP to be a key regulator of junction assembly and disassembly in different in vitro and in vivo systems. In this study, we examine the role of soluble guanylate cyclase (sGC) in junction restructuring in the seminiferous epithelium of the rat testis. First, the interaction of soluble guanylate cyclase beta1 (sGCbeta1; sGC is a heterodimer comprised of an alpha and a beta subunit) with proteins that constitute adherens and tight junctions in the testis was demonstrated. By immunoprecipitation, sGCbeta1 was found to associate with occludin, JAM-A, and ZO-1, as well as with cadherin, catenin, nectin, afadin, ponsin, and espin, suggestive of its role in cell junction dynamics. These results were corroborated in part by immunohistochemistry experiments, which revealed that the localization of sGCbeta1 was largely restricted to the site of the apical and basal ectoplasmic specialization. Next, the role of sGC in junction dynamics was addressed by using an in vivo model of junction restructuring. Administration of Adjudin--a chemical entity known to specifically perturb adhesion between Sertoli and germ cells (i.e., round and elongate(ing) spermatids and most spermatocytes)--resulted in a approximately 1.5-fold increase in sGCbeta1, coinciding with the loss of germ cells from the epithelium. More importantly, the ability of sGCbeta1 to associate with cadherin increased approximately three-fold during Adjudin-mediated restructuring of Sertoli-germ cell junctions, whereas its interaction with tight junction proteins (i.e., occludin and ZO-1) decreased. Taken collectively, these results suggest that sGC participates in the remodeling of cell junctions during spermatogenesis.

Polyglutamine-expanded ataxin-7 activates mitochondrial apoptotic pathway of cerebellar neurons by upregulating Bax and downregulating Bcl-xL

Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant neurodegenerative disorder caused by polyglutamine-expanded ataxin-7. In the present investigation, we expressed disease-causing mutant ataxin-7-Q75 in the primary neuronal culture of cerebellum with the aid of recombinant adenoviruses. Subsequently, this in vitro cellular model of SCA7 was used to study the molecular mechanism by which mutant ataxin-7-Q75 induces neuronal death. TUNEL staining studies indicated that polyglutamine-expanded ataxin-7-Q75 caused apoptotic cell death of cultured cerebellar neurons. Mutant ataxin-7-Q75 induced the formation of active caspase-3 and caspase-9 without activating caspase-8. Polyglutamine-expanded ataxin-7-Q75 promoted the release of apoptogenic cytochrome-c and Smac from mitochondria, which was preceded by the downregulation of Bcl-x(L) protein and upregulation of Bax protein expression in cultured cerebellar neurons. Further real-time TaqMan RT-PCR assays showed that mutant ataxin-7-Q75 upregulated Bax mRNA level and downregulated Bcl-x(L) mRNA expression in the primary neuronal culture of cerebellum. The present study provides the evidence that polyglutamine-expanded ataxin-7-Q75 activates mitochondria-mediated apoptotic cascade and induces neuronal death by upregulating Bax expression and downregulating Bcl-x(L) expression of cerebellar neurons.

EFFECTS OF POLYAMINES ON TWO STRAINS OF TRYPANOSOMA BRUCEI IN INFECTED RATS AND IN VITRO CULTURE

We studied the effects of polyamines, which are necessary for proliferation and antioxidation in Trypanosoma brucei gambiense Wellcome strain (WS) and Trypanosoma brucei brucei ILtat 1.4 strain (IL). No difference was found in activity of ornithine decarboxylase (ODC), a key enzyme in polyamine synthesis in trypanosomes, in both strains maintained in vitro; higher (P < 0.05) ODC values were found in IL in vivo. However, WS in vivo exhibited higher proliferation rates with higher spermidine content and decreased host survival times than IL. The in vitro proliferation and polyamine contents of WS increased with the addition of polyamine to the 1-difluoromethylornithine culture medium, but not IL. These results suggested that WS uses extracellular polyamine for proliferation. In the in vitro culture, WS was less tolerant of hydrogen peroxide (oxidative stress) than IL, and malondialdehyde levels in WS were higher than in IL. The expression of trypanothione synthetase mRNA in WS in vitro was higher than in IL. These results suggest that IL is dependent on the synthesis of polyamines for proliferation and reduction of oxidative stress, whereas WS is dependent on the uptake of extracellular polyamines. A thorough understanding of the differences in the metabolic capabilities of various trypanosomes is important for the design of more effective medical treatments.

Polyglutamine-expanded ataxin-3 activates mitochondrial apoptotic pathway by upregulating Bax and downregulating Bcl-xL

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disease caused by polyglutamine-expanded ataxin-3. In the present study, we expressed disease-causing mutant ataxin-3-Q79 in neuronal cultures of cerebellum, striatum and substantia nigra by using recombinant adenoviruses. Subsequently, SCA3 cellular model was used to investigate the molecular mechanism by which ataxin-3-Q79 causes neuronal death. TUNEL staining studies showed that ataxin-3-Q79 induced apoptotic death of cerebellar, striatal or substantia nigra neurons. Ataxin-3-Q79 activated caspase-3 and caspase-9 without inducing the formation of active caspase-8. Ataxin-3-Q79 promoted mitochondrial release of cytochrome c and Smac, which was preceded by the upregulation of Bax protein and downregulation of Bcl-x(L) protein expression. Real-time TaqMan RT-PCR assays demonstrated that ataxin-3-Q79 upregulated Bax mRNA level and downregulated Bcl-xL mRNA expression in striatal, cerebellar and substantia nigra neurons. Our results suggest that polyglutamine-expanded ataxin-3-Q79 activates mitochondrial apoptotic pathway and induces neuronal death by upregulating Bax expression and downregulating Bcl-xL expression.

Ineffective erythropoiesis in mutant mice with deficient pyruvate kinase activity

OBJECTIVE

A deficiency of pyruvate kinase (PK) is the most common cause of hereditary nonspherocytic anemia due to glycolytic enzyme defects. Red cells are poorly deformable due to adenosine triphosphate depletion in individuals with a PK deficiency and are destroyed in the microcirculation of the reticuloendothelial system, leading to extravascular hemolysis. The pathophysiology of PK deficiency has been widely studied in PK-deficient mice (PK-1(slc)). We examined the effects of a PK deficiency on erythroid progenitor maturation using these mice.

MATERIALS AND METHODS

The appearance of apoptotic cells in spleen of PK-1(slc) mice was examined by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) staining. We also assayed hematopoietic stem cell colony formation in vitro in the spleen of PK-1(slc) mice, to investigate erythropoiesis, and annexin V binding, as a measure of apoptotic cells in constitutive erythroid colonies, to evaluate the maturation of erythroid progenitors.

RESULTS

The number of hematopoietic progenitors including colony-forming unit erythroids, burst-forming unit erythroids (BFU-E), colony-forming unit granulocyte-macrophages, and multilineage colony-forming units in the spleens of PK-1(slc) was remarkably increased indicating hematopoiesis, and enhanced erythropoiesis in particular. TUNEL assays identified apoptotic cells in the splenic red pulp of the PK-1(slc) mice. Two-color flow cytometry detected apoptotic cells among anti-TER119-positive cells, suggesting that apoptotic cells were of erythroid lineage. Cells undergoing apoptosis were detected in cultures of BFU-E generated from bone marrow cells of PK-1(slc) mice.

CONCLUSIONS

The results in this study indicate that the metabolic disturbance in PK deficiency alters not only the survival of red cells but also the maturation of erythroid progenitors, resulting in ineffective erythropoiesis.

Global ischemia downregulates the function of metabotropic glutamate receptor subtype 5 in hippocampal CA1 pyramidal neurons

Within the hippocampus, electrophysiological and immunohistochemical studies showed that metabotropic glutamate receptor subtype 5 (mGluR5) is the major postsynaptic mGluR expressed in CA1 pyramidal neurons. To better understand the role of mGluR5 in ischemia-induced neuronal death, whole-cell patch-clamp recordings using hippocampal slices were performed to investigate the functional change of mGluR5 in CA1 pyramidal neurons following transient global ischemia. Our results indicated that 6 to 24 h after global ischemia, mGluR5-induced cationic currents and mGluR5-mediated enhancement of NMDA-evoked currents in CA1 pyramidal neurons were significantly reduced. Further TaqMan real-time quantitative RT-PCR assay showed that mGluR5 mRNA expression in hippocampal CA1 region or single CA1 pyramidal neurons was significantly downregulated following ischemic insults. The present study suggests that transient global ischemia downregulates mGluR5 function of CA1 pyramidal neurons by decreasing mGluR5 mRNA and that the resulting reduced mGluR5-mediated excitotoxicity could contribute to the survival of CA1 pyramidal neurons after ischemic insult.

Glyceraldehyde-3-phosphate dehydrogenase, apoptosis, and neurodegenerative diseases

Increasing evidence supports the notion that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a protein with multiple functions, including its surprising role in apoptosis. GAPDH is overexpressed and accumulates in the nucleus during apoptosis induced by a variety of insults in diverse cell types. Knockdown of GAPDH using an antisense strategy demonstrates its involvement in the apoptotic cascade in which GAPDH nuclear translocation appears essential. Knowledge concerning the mechanisms underlying GAPDH nuclear translocation and subsequent cell death is growing. Additional evidence suggests that GAPDH may be an intracellular sensor of oxidative stress during early apoptosis. Abnormal expression, nuclear accumulation, changes in physical properties, and loss of glycolytic activity of GAPDH have been found in cellular and transgenic models as well as postmortem tissues of several neurodegenerative diseases. The interaction of GAPDH with disease-related proteins as well as drugs used to treat these diseases suggests that it is a potential molecular target for drug development.

Multifaceted roles of glycolytic enzymes

Although glycolysis is a biochemical pathway that evolved under ancient anaerobic terrestrial conditions, recent studies have provided evidence that some glycolytic enzymes are more complicated, multifaceted proteins rather than simple components of the glycolytic pathway. These glycolytic enzymes have acquired additional non-glycolytic functions in transcriptional regulation [hexokinase (HK)-2, lactate dehydrogenase A, glyceraldehyde-3-phosphate dehydrogenase (GAPD) and enolase 1], stimulation of cell motility (glucose-6-phosphate isomerase) and the regulation of apoptosis (glucokinase, HK and GAPD). The existence of multifaceted roles of glycolytic proteins suggests that links between metabolic sensors and transcription are established directly through enzymes that participate in metabolism. These roles further underscore the need to consider the non-enzymatic functions of enzymes in proteomic studies of cells and tissues.

Effects of Heparin Administration on Trypanosoma brucei gambiense Infection in Rats

We examined whether heparin administration influences in vivo trypanosome proliferation in infected rats. Administration of heparin every 8 hr via cardiac catheter inhibited growth of Trypanosoma brucei gambiense and prolonged survival of treated rats. Heparin administration increased lipoprotein lipase activity, high-density lipoprotein (HDL) concentration in the blood, and haptoglobin messenger RNA content of the liver. The presence of heparin in culture media did not directly affect proliferation of trypanosomes in vitro. However, the addition of plasma from infected rats treated with heparin to culture media decreased the number of trypanosomes. This effect was decreased by incubating the trypanosomes with benzyl alcohol, a known inhibitor of receptor-mediated endocytosis of lipoprotein. These data suggested that heparin administration reduced the number of trypanosomes in infected rats. Trypanosome lytic factor, a HDL and haptoglobin-related protein, protects humans and some animals from infection by Trypanosoma brucei brucei. In rats, increases in HDL and haptoglobin may affect the proliferation of T. b. gambiense.

Pro-apoptotic protein glyceraldehyde-3-phosphate dehydrogenase promotes the formation of Lewy body-like inclusions

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has long been recognized as a classical glycolytic protein; however, previous studies by our group and others have demonstrated that GAPDH is a general mediator initiating one or more apoptotic cascades. Our most recent findings have elucidated that an expression of a pro-apoptotic protein GAPDH is critically regulated at the promoter region of the gene. Apoptotic signals for its subsequent aggregate formation and nuclear translocation are controlled by the respective functional domains harboured within its cDNA component. In this study, coexpression of GAPDH with either wild-type or mutant (A53T) alpha-synuclein and less likely with beta-synuclein in transfected COS-7 cells was found to induce Lewy body-like cytoplasmic inclusions. Unlike its full-length construct, the deleted mutant GAPDH construct (C66) abolished these apoptotic signals, disfavouring the formation of inclusions. The generated inclusions were ubiquitin- and thioflavin S-positive appearing fibrils. Furthermore, GAPDH coimmunoprecipitated with wild-type alpha-synuclein in this paradigm. Importantly, immunohistochemical examinations of post mortem materials from patients with sporadic Parkinson's disease revealed the colocalized profiles immunoreactive against these two proteins in the peripheral zone of Lewy bodies from the affected brain regions (i.e. locus coeruleus). Moreover, a quantitative assessment showed that about 20% of Lewy bodies displayed both antigenicities. These results suggest that pro-apoptotic protein GAPDH may be involved in the Lewy body formation in vivo, probably associated with the apoptotic death pathway.

Disclosure of a pro-apoptotic glyceraldehyde-3-phosphate dehydrogenase promoter: anti-dementia drugs depress its activation in apoptosis

Overexpression and subsequent nuclear accumulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is involved in neuronal apoptosis induced by several stimuli in which GAPDH antisense oligonucleotides specifically block the increment (2 approximately 3 fold) of GAPDH mRNA contents occurring prior to neuronal death. However, these agents do not affect the basal, constitutive mRNA contents. This suggests that there may be distinct gene regulations for GAPDH mRNA expression. Herein, we cloned two types of promoter regions upstream of this gene; viz., #104 (1.02-kb) and #302 (2.46-kb). These fragments were inserted into the pGL3 luciferase reporter system and transiently transfected into cultured cerebellar neurons undergoing cytosine arabinonucleoside-induced apoptosis. The functional analysis of these constructs revealed that #104, but not #302, increased luciferase activity in response to the apoptotic stimulus. Deletion and replacement mutation analysis of the #104 fragment disclosed the promoter core harbored between the 154-bp and 84-bp domains (3.5-fold activity of the control). Furthermore, anti-dementia drugs (such as Cognex and Aricept) markedly depress the expression of this pro-apoptotic GAPDH promoter activity. Interestingly, immunocytochemical examination of human post-mortem materials from patients with Alzheimer's disease revealed nuclear aggregated GAPDH in neurons of the affected brain regions, implying an association with apoptotic cell death. The current findings indicate that induction of the pro-apoptotic protein GAPDH is genetically regulated at the level of promoter activation, and this protein may be an important molecular target for developing anti-apoptotic therapeutic agents in certain neurological illnesses.

A novel DNA enzyme reduces glycosaminoglycan chains in the glial scar and allows microtransplanted dorsal root ganglia axons to regenerate beyond lesions in the spinal cord

CNS lesions induce production of ECM molecules that inhibit axon regeneration. One major inhibitory family is the chondroitin sulfate proteoglycans (CSPGs). Reduction of their glycosaminoglycan (GAG) chains with chondroitinase ABC leads to increased axon regeneration that does not extend well past the lesion. Chondroitinase ABC, however, is unable to completely digest the GAG chains from the protein core, leaving an inhibitory "stub" carbohydrate behind. We used a newly designed DNA enzyme, which targets the mRNA of a critical enzyme that initiates glycosylation of the protein backbone of PGs, xylosyltransferase-1. DNA enzyme administration to TGF-beta-stimulated astrocytes in culture reduced specific GAG chains. The same DNA enzyme applied to the injured spinal cord led to a strong reduction of the GAG chains in the lesion penumbra and allowed axons to regenerate around the core of the lesion. Our experiments demonstrate the critical role of PGs, and particularly those in the penumbra, in causing regeneration failure in the adult spinal cord.

Neuronal Apoptosis and Protection: Effects of Nitric Oxide and Endoplasmic Reticulum-Related Proteins

This review presents recent findings with regard to the cellular and molecular mechanisms of neuronal apoptosis induced by cerebral ischemia/hypoxia. The protection of neuronal death by hypoxia-induced proteins in the endoplasmic reticulum (ER) is also reviewed. The excess amount of nitric oxide (NO) generated by inducible NO synthase (iNOS) up-regulated in response to ischemic stress causes neuronal apoptosis through following processes; 1) reduction in mitochondrial membrane potential, 2) release of cytochrome c from mitochondria, and 3) activation of caspase-9 and -3, although low concentrations of NO protect against neuronal death. In contrast, hypoxia induces expression of several proteins such as protein disulfide isomerase (PDI), ubiquilin and HRD1 in the endoplasmic reticulum (ER). PDI and ubiquilin are involved in the protection against neuronal apoptosis probably by interacting with each other and enhancing the effects of PDI as a molecular chaperon. HRD1 is also up-regulated by hypoxia in the ER and induces protection against hypoxia-induced neuronal apoptosis by activating the protein degradation system. The present review hopefully gives pertinent suggestions for further studies on the development of novel prophylactic/therapeutics for neuronal apoptosis-related diseases.