Rapid up-regulation of peptide elongation factor EF-1alpha protein levels is an immediate early event during oxidative stress-induced apoptosis

Exploiting Translation Machinery for Cancer Therapy: Translation Factors as Promising Targets

Eukaryotic protein translation has slowly gained the scientific community's attention for its advanced and powerful therapeutic potential. However, recent technical developments in studying ribosomes and global translation have revolutionized our understanding of this complex multistep process. These developments have improved and deepened the current knowledge of mRNA translation, sparking excitement and new possibilities in this field. Translation factors are crucial for maintaining protein synthesis homeostasis. Since actively proliferating cancer cells depend on protein synthesis, dysregulated protein translation is central to tumorigenesis. Translation factors and their abnormal expressions directly affect multiple oncogenes and tumor suppressors. Recently, small molecules have been used to target translation factors, resulting in translation inhibition in a gene-specific manner, opening the door for developing translation inhibitors that can lead to novel chemotherapeutic drugs for treating multiple cancer types caused by dysregulated translation machinery. This review comprehensively summarizes the involvement of translation factors in tumor progression and oncogenesis. Also, it sheds light on the evolution of translation factors as novel drug targets for developing future therapeutic drugs for treating cancer.

The eEF1A protein in cancer: Clinical significance, oncogenic mechanisms, and targeted therapeutic strategies

Eukaryotic elongation factor 1A (eEF1A) is among the most abundant proteins in eukaryotic cells. Evolutionarily conserved across species, eEF1A is in charge of translation elongation for protein biosynthesis as well as a plethora of non-translational moonlighting functions for cellular homeostasis. In malignant cells, however, eEF1A becomes a pleiotropic driver of cancer progression via a broad diversity of pathways, which are not limited to hyperactive translational output. In the past decades, mounting studies have demonstrated the causal link between eEF1A and carcinogenesis, gaining deeper insights into its multifaceted mechanisms and corroborating its value as a prognostic marker in various cancers. On the other hand, an increasing number of natural and synthetic compounds were discovered as anticancer eEF1A-targeting inhibitors. Among them, plitidepsin was approved for the treatment of multiple myeloma whereas metarrestin was currently under clinical development. Despite significant achievements in these two interrelated fields, hitherto there lacks a systematic examination of the eEF1A protein in the context of cancer research. Therefore, the present work aims to delineate its clinical implications, molecular oncogenic mechanisms, and targeted therapeutic strategies as reflected in the ever expanding body of literature, so as to deepen mechanistic understanding of eEF1A-involved tumorigenesis and inspire the development of eEF1A-targeted chemotherapeutics and biologics.

A Novel Anderson-Evans Polyoxometalate-based Metal-organic Framework Composite for the Highly Selective Isolation and Purification of Cytochrome C from Porcine Heart

Anderson-Evans type polyoxometalate group (Na₆[TeW₆O₂₄]·22 H₂O, TeW₆) was combined with porous metal-organic framework ZIF-8 by electrostatic interaction to obtain a novel Anderson-Evans polyoxometalate-based metal-organic framework composite, TeW₆ @ZIF-8. FT-IR, Raman, XRD, TG, DSC, SEM, and TEM were used to characterize the composite. It was proved that the Anderson-Evans type polyoxometalate group TeW₆ was successfully hybridized with metal-organic framework ZIF-8, and the composite possesses good stability. Based on the potential interaction between TeW₆ and proteins and the coordination between imidazole groups in ZIF-8 and proteins with a porphyrin ring structure, the adsorption selectivity towards different proteins on the TeW₆ @ZIF-8 composite was studied in this work. The experiment results showed that the TeW₆ @ZIF-8 composite was selectively adsorbed to cytochrome C. At pH 11.0, the adsorption efficiency of 94.01% was obtained for processing 1.0 mL 100 μg mL^-1 cytochrome C with 3.0 mg TeW₆ @ZIF-8 composite. The adsorption behavior of cytochrome C fits well with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 232.56 mg g^-1. The retained cytochrome C could be readily recovered by 1% SDS (m/m), giving rise to a recovery of 65.6%. Circular dichroism spectra indicate no conformational change for cytochrome C after the adsorption and desorption processes, demonstrating the favorable biocompatibility of TeW₆ @ZIF-8 composite. In applying practical samples, SDS-PAGE results showed that cytochrome C was successfully isolated and purified by TeW₆ @ZIF-8 composite from porcine heart protein extract, which is further identified with LC-MS/MS. Thus, a new strategy for separating and purifying cytochrome C from the porcine heart using TeW₆ @ZIF-8 composite as an adsorbent was established.

Expression and Clinical Value of Eukaryotic Translation Elongation Factor 1A1 (EEF1A1) in Diffuse Large B Cell Lymphoma

Background

The eukaryotic translation elongation factor 1A1 (EEF1A1) participates in protein translation and has been reported to be involved in tumor progression such as hepatocellular carcinoma. Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy in adults. In the present study, we aimed to detect the expression of EEF1A1 in DLBCL and to analyze its relationship with prognosis.

Methods

We reviewed medical records of DLBCL patients in our hospital and evaluated their expression level of EEF1A1 in tumor tissues using immunohistochemical (IHC) assay. The Chi-square method was used for correlation analysis. The Kaplan–Meier method with Log rank test was used for univariate analysis. Cox proportional hazards model was used for multivariate analysis. Cellular and mice models were introduced to validate its oncogenic role.

Results

EEF1A1 expression in tumor cells was higher in certain DLBCL cases. Patients with higher EEF1A1 expression were more likely to have advanced tumor stage and poorer 5-year overall survival (OS) rates. EEF1A1 expression in tumor cells was an independent risk predictor for OS (P < 0.05). Cellular assays demonstrated that EEF1A1-shRNA significantly inhibited lymphoma cell proliferation. The study of xenografts further verified the effect of EEF1A1-shRNA on suppressing tumor growth in vivo.

Conclusion

EEF1A1 positivity predicts short survival in DLBCL patients. For patients with higher EEF1A1 expression, more strategy such as anti-EEF1A1 antibody treatment should be developed.

Multivariate transcriptome analysis identifies networks and key drivers of chronic lymphocytic leukemia relapse risk and patient survival

BACKGROUND

Chronic lymphocytic leukemia (CLL) is an indolent heme malignancy characterized by the accumulation of CD5+ CD19+ B cells and episodes of relapse. The biological signaling that influence episodes of relapse in CLL are not fully described. Here, we identify gene networks associated with CLL relapse and survival risk.

METHODS

Networks were investigated by using a novel weighted gene network co-expression analysis method and examining overrepresentation of upstream regulators and signaling pathways within co-expressed transcriptome modules across clinically annotated transcriptomes from CLL patients (N = 203). Gene Ontology analysis was used to identify biological functions overrepresented in each module. Differential Expression of modules and individual genes was assessed using an ANOVA (Binet Stage A and B relapsed patients) or T-test (SF3B1 mutations). The clinical relevance of biomarker candidates was evaluated using log-rank Kaplan Meier (survival and relapse interval) and ROC tests.

RESULTS

Eight distinct modules (M2, M3, M4, M7, M9, M10, M11, M13) were significantly correlated with relapse and differentially expressed between relapsed and non-relapsed Binet Stage A CLL patients. The biological functions of modules positively correlated with relapse were carbohydrate and mRNA metabolism, whereas negatively correlated modules to relapse were protein translation associated. Additionally, M1, M3, M7, and M13 modules negatively correlated with overall survival. CLL biomarkers BTK, BCL2, and TP53 were co-expressed, while unmutated IGHV biomarker ZAP70 and cell survival-associated NOTCH1 were co-expressed in modules positively correlated with relapse and negatively correlated with survival days.

CONCLUSIONS

This study provides novel insights into CLL relapse biology and pathways associated with known and novel biomarkers for relapse and overall survival. The modules associated with relapse and overall survival represented both known and novel pathways associated with CLL pathogenesis and can be a resource for the CLL research community. The hub genes of these modules, e.g., ARHGAP27P2, C1S, CASC2, CLEC3B, CRY1, CXCR5, FUT5, MID1IP1, and URAHP, can be studied further as new therapeutic targets or clinical markers to predict CLL patient outcomes.

Identification of proteins involved in transcription/translation (eEF 1A1) as an inhibitor of Bax induced apoptosis

Eukaryotic elongation factor 1A1 (eEF1A1) is central to translational activity. It is involved in complexes that form signal transduction with protein kinase C, as well as being a signal transducer and activator of transcription 3. eEF1A1 and eEF1A2 are isoforms of the alpha subunit of elongating factor 1 complex. It has been reported that eEF1A1 is expressed in most human tissues but the brain, skeletal muscle and heart. eEF1A1 has been linked to both apoptosis and anti-apoptotic activities. In this study, eEF1A1 was co-expressed with Bax, a proapoptotic protein via heterologous expression of recombinant DNA in yeast cells. Assays were carried out to monitor the fate and state of yeast cells when eEF1A1 was co-expressed with Bax. The yeast strain (bearing an integrated copy of the Bax gene) was transformed with an episomal 2-micron plasmid that encodes HA-tagged eEF1A1 gene. The resultant strain would allow co-expression of Bax and eEF1A1 in yeast cells, Bax being under the control of the GAL1 promoter, while the PGK1 promoter drives eEF1A1 expression. Bcl 2A1, a known anti-apoptotic protein, was also co-expressed with Bax in yeast cells as a positive control, to study the anti-apoptotic characteristic of eEF-1A1. The part eEF1A1 plays in apoptosis has been contentious, amidst the pro and anti-apoptotic properties of eEF1A1, it was shown clearly, in this study that eEF1A1 portrays only anti-apoptotic property in the presence of pro-apoptotic protein, Bax.

Inhibition of the antioxidant enzyme PRDX1 activity promotes MPP+-induced death in differentiated SH-SY5Y cells and may impair its colocalization with eEF1A2

AIM

eEF1A2 is highly expressed in postmitotic cells and has been reported to interact with the antioxidant enzyme peroxiredoxin 1 (PRDX1). PRDX1 is involved in motor neuron differentiation. Here, we studied the relationship between eEF1A2 and PRDX1 during dopaminergic neuron differentiation, and examined their possible association in an oxidative stress model of Parkinson's disease (PD).

MAIN METHODS

Expression of eEF1A2 and PRDX1 in SH-SY5Y cells at various durations of retinoic acid (RA) induction was detected using qRT-PCR, Western blotting and immunofluorescence. Neurons of 10-day differentiation were treated with the PRDX1 inhibitor H7, MPP⁺ and H7 plus MPP⁺. The cell viability, the amounts of apoptotic nuclei, DHE signals, and the expression of p53, p-Akt and p-mTOR were determined. The colocalization of eEF1A2 and PRDX1 was visualized using confocal microscopy.

KEY FINDINGS

eEF1A2 gradually increased after RA-induced differentiation of SH-SY5Y cells, while PRDX1 protein gradually decreased. MPP⁺ treatment increased eEF1A2 in both undifferentiated and differentiated neurons; however, PRDX1 appeared to elevate only in mature neurons. The inhibition of the PRDX1 activity with H7 promoted MPP⁺-induced cell death, as evidenced by decreased cell viability, increased apoptotic nuclei, increased the DHE signal, and increased p53. However, H7 induced the activation of the prosurvival Akt and mTOR in MPP⁺-treated cells. Besides, a colocalization of eEF1A2 and PRDX1 was evidenced in MPP⁺-treated neurons. This colocalization was possibly prevented by inhibiting the PRDX1 activity, resulting in aggravated neuronal death.

SIGNIFICANCE

Our results suggest that the possible association between eEF1A2 and PRDX1 may be a promising target for modifying neuronal death in PD.

Effects of eEF1A2 knockdown on autophagy in an MPP+-induced cellular model of Parkinson's disease

1-Methyl-4-phenylpyridinium ion (MPP⁺) is widely used to induce a cellular model of Parkinson's disease (PD) in dopaminergic cell lines. Downregulation of the protein translation elongation factor 1 alpha (eEF1A) has been reported in the brain tissue of PD patients. eEF1A2, an isoform of eEF1A, is associated with lysosome biogenesis that involves the autophagy process. However, the role of eEF1A2 on autophagic activity in PD has not been elucidated. In this work, we investigated the role of eEF1A2 on autophagy using eEF1A2 siRNA knockdown in differentiated SH-SY5Y neuronal cells treated with MPP⁺. We found that eEF1A2 was upregulated in differentiated cells, which could be silenced by eEF1A2 siRNA. Significantly, cells treated with MPP⁺ after eEF1A2 knockdown showed a decreased number of LC3 puncta, decreased LC3-II/LC3-I ratio, and decreased phospho-Beclin-1, compared to the MPP⁺ alone group. These cells showed extensive areas of mitochondria damage, with a reduction of mitochondrial membrane potential, but reduced mitophagy as indicated by the reduced colocalization of LC3 puncta with damaged mitochondria. Cells with eEF1A2 siRNA plus MPP⁺ treatment aggravated α-synuclein accumulation but reduced colocalization with LC3. As a result, eEF1A2 knockdown decreased viability, increased apoptotic nuclei, increased caspase-3/7 activation and increased cleaved caspase-3 when cells were treated with MPP⁺. These results suggest that eEF1A2 is essential for dopaminergic neuron survival against MPP⁺, in part through autophagy regulation.

Proteomics of human glomerulonephritis by laser microdissection and liquid chromatography-tandem mass spectrometry

Aim

Laser microdissection (LMD) and liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) enable clinicians to analyse proteins from tissue sections. In nephrology, these methods are used to diagnose diseases of abnormal protein deposition, such as amyloidosis, but they are seldom applied to the diagnosis and pathophysiological understanding of human glomerular diseases.

Methods

Renal biopsy specimens were obtained from five patients with IgA nephropathy (IgAN), five patients with membranous nephropathy (MN) and five kidney transplant donors (as controls). From 10‐μm‐thick sections of formalin‐fixed, paraffin‐embedded specimens, 0.3‐mm² samples of glomerular tissue were subjected to LMD. The samples were analysed by LC‐MS/MS and investigated clinically and histologically.

Results

From the control glomeruli, we identified more than 300 types of proteins. In patients with IgAN, we detected significant increases not only in IgA1 and in C3, but also in the factors related to oxidative stress and cell proliferation in comparison to the controls. In patients with MN, levels of IgG1, IgG4, C3, C4a and phospholipase‐A2‐receptor were significantly elevated in comparison to the controls, as were the aforementioned factors related to oxidative stress and cell proliferations detected in IgAN.

Conclusion

Application of LMD and LC‐MS/MS to renal biopsy specimens enabled us to identify not only pathognomonic proteins for the diagnosis, but also several factors possibly involved in the pathogenesis of human glomerular diseases.

This paper examined the possible application of laser microdissection and liquid chromatography‐tandem mass spectrometry to renal biopsy specimens to clarify the pathogenesis of human glomerular diseases.

Eukaryotic elongation factor 2 is involved in the anticoccidial action of diclazuril in the second-generation merozoites of Eimeria tenella

Eimeria tenella, an obligate intracellular parasite, can actively invade the cecal epithelial cells of chickens and cause severe enteric disease. Eukaryotic elongation factor 2 (eEF2) plays a major role in protein synthesis and cell survival. This study aims to explore the exact mechanisms underlying diclazuril inhibition in second-generation merozoites of E. tenella. The eEF2 cDNA of the second-generation merozoites of E. tenella (EtEF2) was cloned by reverse transcriptase polymerase chain reaction and rapid amplification of cDNA ends. Diclazuril-induced expression profiles of EtEF2 were also analyzed. The cloned full-length cDNA (2893 bp) of the EtEF2 nucleotide sequence encompassed a 2499 bp open reading frame (ORF) that encoded a polypeptide of 832 residues with an estimated molecular mass of 93.12 kDa and a theoretical isoelectric point of 5.99. The EtEF2 nucleotide sequence was submitted to the GenBank database with the accession number KF188423. The EtEF2 protein sequence shared 99 % homology with the eEF2 sequence of Toxoplasma gondii (GenBank XP_002367778.1). The GTPase activity domain and ADP-ribosylation domain were conserved signature sequences of the eEF2 gene family. The changes in the transcriptional and translational levels of EtEF2 were detected through quantitative real-time PCR and Western blot analyses. The mRNA expression level of EtEF2 was 2.706 fold increases and the protein level of EtEF2 was increased 67.31 % under diclazuril treatment. In addition, the localization of EtEF2 was investigated through immunofluorescence assay. Experimental results demonstrated that EtEF2 was distributed primarily in the cytoplasm of second-generation merozoites, and its fluorescence intensity was enhanced after diclazuril treatment. These findings indicated that EtEF2 may have an important role in understanding the signaling mechanism underlying the anticoccidial action of diclazuril and could be a promising target for novel drug exploration.

Alterations in Eukaryotic Elongation Factor complex proteins (EEF1s) in cancer and their implications in epigenetic regulation

AIMS

In the cell, both transcriptional and translational processes are tightly regulated. Cancer is a multifactorial disease characterized by aberrant protein expression. Since epigenetic control mechanisms are also frequently disrupted during carcinogenesis, they have been the center of attention in cancer research within the past decades. EEF1 complex members, which are required for the elongation process in eukaryotes, have recently been implicated in carcinogenesis. This study aims to investigate genetic alterations within EEF1A1, EEF1A2, EEF1B2, EEF1D, EEF1E1 and EEF1G genes and their potential effects on epigenetic regulation mechanisms.

MATERIALS AND METHODS

In this study, we analyzed DNA sequencing and mRNA expression data available on The Cancer Genome Atlas (TCGA) across different cancer types to detect genetic alterations in EEF1 genes and investigated their potential impact on selected epigenetic modulators.

KEY FINDINGS

We found that EEF1 complex proteins were deregulated in several types of cancer. Lower EEF1A1, EEF1B2, EEF1D and EEF1G levels were correlated with poor survival in glioma, while lower EEF1B2, EEF1D and EEF1E1 levels were correlated with better survival in hepatocellular carcinoma. We detected genetic alterations within EEF1 genes in up to 35% of the patients and showed that these alterations resulted in down-regulation of histone modifying enzymes KMT2C, KMT2D, KMT2E, KAT6A and EP300.

SIGNIFICANCE

Here in this study, we showed that EEF1 deregulations might result in differential epigenomic landscapes, which affect the overall transcriptional profile, contributing to carcinogenesis. Identification of these molecular distinctions might be useful in developing targeted drug therapies and personalized medicine.

Fatty acylCoA synthetase FadD13 regulates proinflammatory cytokine secretion dependent on the NF-κB signalling pathway by binding to eEF1A1

Mycobacterium tuberculosis (Mtb) manipulates multiple host defence pathways to survive and persist in host cells. Understanding Mtb–host cell interaction is crucial to develop an efficient means to control the disease. Here, we applied the Mtb proteome chip, through separately interacting with H37Ra and H37Rv stimulated macrophage lysates, screened 283 Mtb differential proteins. Through primary screening, we focused on fatty acylCoA synthetase FadD13. Mtb FadD13 is a potential drug target, but its role in infection remains unclear. Deletion of FadD13 in Mtb reduced the production of proinflammatory cytokines IL‐1β, IL‐18, and IL‐6. Bimolecular fluorescence complementation and colocalization showed that the binding partner of FadD13 in macrophage was eEF1A1 (a translation elongation factor). Knockdown eEF1A1 expression in macrophage abrogated the promotion of proinflammatory cytokines induced by FadD13. In addition, ΔfadD13 mutant decreased the expression of the NF‐κB signalling pathway related proteins p50 and p65, so did the eEF1A1 knockdown macrophage infected with H37Rv. Meanwhile, we found that deletion of FadD13 reduced Mtb survival in macrophages during Mtb infection, and purified FadD13 proteins induced broken of macrophage membrane. Taken together, FadD13 is crucial for Mtb proliferation in macrophages, and it plays a key role in the production of proinflammatory cytokines during Mtb infection.

Styryl-cinnamate hybrid inhibits glioma by alleviating translation, bioenergetics and other key cellular responses leading to apoptosis

Gliomas are lethal and aggressive form of brain tumors with resistance to conventional radiation and cytotoxic chemotherapies; inviting continuous efforts for drug discovery and drug delivery. Interestingly, small molecule hybrids are one such pharmacophore that continues to capture interest owing to their pluripotent medicinal effects. Accordingly, we earlier reported synthesis of potent Styryl-cinnamate hybrids (analogues of Salvianolic acid F) along with its plausible mode of action (MOA). We explored iTRAQ-LC/MS-MS technique to deduce differentially expressed landscape of native & phospho-proteins in treated glioma cells. Based on this, Protein-Protein Interactome (PPI) was looked into by employing computational tools and further validated in vitro. We hereby report that the Styryl-cinnamate hybrid, an analogue of natural Salvianolic acid F, alters key regulatory proteins involved in translation, cytoskeleton development, bioenergetics, DNA repair, angiogenesis and ubiquitination. Cell cycle analysis dictates arrest at G0/G1 stage along with reduced levels of cyclin D; involved in G1 progression. We discovered that Styryl-cinnamate hybrid targets glioma by intrinsically triggering metabolite-mediated stress. Various oncological circuits alleviated by the potential drug candidate strongly supports the role of such pharmacophores as anticancer drugs. Although, further analysis of SC hybrid in treating xenografts or solid tumors is yet to be explored but their candidature has gained huge impetus through this study. This study equips us better in understanding the shift in proteomic landscape after treating glioma cells with SC hybrid. It also allows us to elicit molecular targets of this potential drug before progressing to preclinical studies.

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.

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of "generalized cellular stress," which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of "committed" tumor cells.

The expression profile and prognostic significance of eukaryotic translation elongation factors in different cancers

Eukaryotic translation factors, especially initiation factors have garnered much attention with regards to their role in the onset and progression of different cancers. However, the expression levels and prognostic significance of translation elongation factors remain poorly explored in different cancers. In this study, we have investigated the mRNA transcript levels of seven translation elongation factors in different cancer types using Oncomine and TCGA databases. Furthermore, we have identified the prognostic significance of these factors using Kaplan-Meier Plotter and SurvExpress databases. We observed altered expression levels of all the elongation factors in different cancers. Higher expression of EEF1A2, EEF1B2, EEF1G, EEF1D, EEF1E1 and EEF2 was observed in most of the cancer types, whereas reverse trend was observed for EEF1A1. Overexpression of many factors predicted poor prognosis in breast (EEF1D, EEF1E1, EEF2) and lung cancer (EEF1A2, EEF1B2, EEF1G, EEF1E1). However, we didn’t see any common correlation of expression levels of elongation factors with survival outcomes across cancer types. Cancer subtype stratification showed association of survival outcomes and expression levels of elongation factors in specific sub-types of breast, lung and gastric cancer. Most interestingly, we observed a reciprocal relationship between the expression levels of the two EEF1A isoforms viz. EEF1A1 and EEF1A2, in most of the cancer types. Our results suggest that translation elongation factors can have a role in tumorigenesis and affect survival in cancer specific manner. Elongation factors have potential to serve as biomarkers and therapeutic drug targets, yet further study is required. Reciprocal relationship of differential expression between EEF1A isoforms observed in multiple cancer types indicates opposing roles in cancer and needs further investigation.

Treatment with didemnin B, an elongation factor 1A inhibitor, improves hepatic lipotoxicity in obese mice

Eukaryotic elongation factor EEF1A1 is induced by oxidative and ER stress, and contributes to subsequent cell death in many cell types, including hepatocytes. We recently showed that blocking the protein synthesis activity of EEF1A1 with the peptide inhibitor, didemnin B, decreases saturated fatty acid overload-induced cell death in HepG2 cells. In light of this and other recent work suggesting that limiting protein synthesis may be beneficial in treating ER stress-related disease, we hypothesized that acute intervention with didemnin B would decrease hepatic ER stress and lipotoxicity in obese mice with nonalcoholic fatty liver disease (NAFLD). Hyperphagic male ob/ob mice were fed semipurified diet for 4 weeks, and during week 5 received i.p. injections of didemnin B or vehicle on days 1, 4, and 7. Interestingly, we observed that administration of this compound modestly decreased food intake without evidence of illness or distress, and thus included an additional control group matched for food consumption with didemnin B-treated animals. Treatment with didemnin B improved several characteristics of hepatic lipotoxicity to a greater extent than the effects of caloric restriction alone, including hepatic steatosis, and some hepatic markers of ER stress and inflammation (GRP78, Xbp1s, and Mcp1). Plasma lipid and lipoprotein profiles and histopathological measures of NAFLD, including lobular inflammation, and total NAFLD activity score were also improved by didemnin B. These data indicate that acute intervention with the EEF1A inhibitor, didemnin B, improves hepatic lipotoxicity in obese mice with NAFLD through mechanisms not entirely dependent on decreased food intake, suggesting a potential therapeutic strategy for this ER stress-related disease.

Molecular characterization, expression analysis and RNAi knock-down of elongation factor 1α and 1γ from Nilaparvata lugens and its yeast-like symbiont

In the present paper, four cDNAs encoding the alpha and gamma subunits of elongation factor 1 (EF-1) were cloned and sequenced from Nilaparvata lugens, named NlEF-1α, NlEF-1γ, and its yeast-like symbiont (YLS), named YsEF-1α and YsEF-1γ, respectively. Comparisons with sequences from other species indicated a greater conservation for EF-1α than for EF-1γ. NlEF-1α has two identical copies. The deduced amino acid sequence homology of NlEF-1α and NlEF-1γ is 96 and 64%, respectively, compared with Homalodisca vitripennis and Locusta migratoria. The deduced amino acid sequence homology of YsEF-1α and YsEF-1γ is 96 and 74%, respectively, compared with Metarhizium anisopliae and Ophiocordyceps sinensis. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis revealed that the expression level of NlEF-1α and NlEF-1γ mRNA in hemolymph, ovary, fat body and salivary glands were higher than the midgut and leg tissue. YsEF-1α and YsEF-1γ was highly expressed in fat body. The expression level of NlEF-1α was higher than that of NlEF-1γ. Through RNA interference (RNAi) of the two genes, the mortality of nymph reached 92.2% at the 11th day after treatment and the ovarian development was severely hindered. The RT-qPCR analysis verified the correlation between mortality, sterility and the down-regulation of the target genes. The expression and synthesis of vitellogenin (Vg) protein in insects injected with NlEF-1α and NlEF-1γ double-stranded RNA (dsRNA) was significantly lower than control groups. Attempts to knockdown the YsEF-1 genes in the YLS was unsuccessful. However, the phenotype of N. lugens injected with YsEF-1α dsRNA was the same as that injected with NlEF-1α dsRNA, possibly due to the high similarity (up to 71.9%) in the nucleotide sequences between NlEF-1α and YsEF-1α. We demonstrated that partial silencing of NlEF-1α and NlEF-1γ genes caused lethal and sterility effect on N. lugens. NlEF-1γ shares low identity with that of other insects and therefore it could be a potential target for RNAi-based pest management.

Unphosphorylated STAT1 represses apoptosis in macrophages during Mycobacteriumtuberculosis infection

In murine macrophages infected with Mycobacterium tuberculosis (Mtb), the level of phosphorylated STAT1 (P-STAT1), which drives the expression of many pro-apoptosis genes, increases quickly but then declines over a period of hours. By contrast, infection induces a continued increase in the level of unphosphorylated STAT1 that persists for several days. Here, we found that the level of unphosphorylated STAT1 correlated with the intracellular bacterial burden during the later stages of infection. To investigate the significance of a high level of unphosphorylated STAT1, we increased its concentration exogenously, and found that the apoptosis rate induced by Mtb was sufficiently decreased. Further experiments confirmed that unphosphorylated STAT1 affects the expression of several immune-associated genes and lessens the sensitivity of macrophages to CD95 (FAS)-mediated apoptosis during Mtb infection. Furthermore, we characterized 149 proteins that interacted with unphosphorylated STAT1 and the interactome network. The cooperation between unphosphorylated STAT1 and STAT3 results in downregulation of CD95 expression. Additionally, we verified that unphosphorylated STAT1 and IFIT1 competed for binding to eEF1A. Taken together, our data show that the role of unphosphorylated STAT1 differs from that of P-STAT1, and represses apoptosis in macrophages to promote immune evasion during Mtb infection.

Identification of vitamin D3 target genes in human breast cancer tissue

Multiple epidemiological studies have shown that high vitamin D₃ status is strongly associated with improved breast cancer survival. To determine the molecular pathways influenced by 1 alpha, 25-dihydroxyvitamin D₃ (1,25D) in breast epithelial cells we isolated RNA from normal human breast and cancer tissues treated with 1,25D in an ex vivo explant system. RNA-Seq revealed 523 genes that were differentially expressed in breast cancer tissues in response to 1,25D treatment, and 127 genes with altered expression in normal breast tissues. GoSeq KEGG pathway analysis revealed 1,25D down-regulated cellular metabolic pathways and enriched pathways involved with intercellular adhesion. The highly 1,25D up-regulated target genes CLMN, SERPINB1, EFTUD1, and KLK6were selected for further analysis and up-regulation by 1,25D was confirmed by qRT-PCR analysis in breast cancer cell lines and in a subset of human clinical samples from normal and cancer breast tissues. Ketoconazole potentiated 1,25D-mediated induction of CLMN, SERPINB1, and KLK6 mRNA through inhibition of 24-hydroxylase (CYP24A1) activity. Elevated expression levels of CLMN, SERPINB1, and KLK6 are associated with prolonged relapse-free survival for breast cancer patients. The major finding of the present study is that exposure of both normal and malignant breast tissue to 1,25D results in changes in cellular adhesion, metabolic pathways and tumor suppressor-like pathways, which support epidemiological data suggesting that adequate vitamin D₃ levels may improve breast cancer outcome.

Comparative mRNA Expression of eEF1A Isoforms and a PI3K/Akt/mTOR Pathway in a Cellular Model of Parkinson's Disease

The PI3K/Akt/mTOR pathway is one of dysregulated pathways in Parkinson's disease (PD). Previous studies in nonneuronal cells showed that Akt regulation can be increased by eukaryotic protein elongation factor 1 alpha 2 (eEF1A2). eEF1A2 is proposed to contribute protection against apoptotic death, likely through activation of the PI3K/Akt pathway. Whether eEF1A2 plays a role in the prevention of cell death in PD has not been investigated. Recently, gene profiling on dopaminergic neurons from postmortem PD patients showed both upregulation and downregulation of some PI3K and mTOR genes. In this paper, the expression of all gene members of the PI3K/Akt/mTOR pathway in relation to those of the eEF1A isoforms in a cellular model of PD was investigated at the mRNA level. The results showed a similar trend of upregulation of genes of the eEF1A isoforms (eEF1A1 and eEF1A2) and of the PI3K (classes I–III)/Akt (Akt1, Akt2, and Akt3)/mTOR (mTORC1 and mTORC2) pathway in both nondifferentiated and differentiated SH-SY5Y dopaminergic cells treated with 1-methyl-4-phenylpyridinium (MPP⁺). Upregulation of eEF1A2, Akt1, and mTORC1 was consistent with the relative increase of eEF1A2, Akt, phospho-Akt, and mTORC1 proteins. The possible role of eEF1A isoforms in the regulation of the PI3K/Akt/mTOR pathway in PD is discussed.

Genome-wide analysis of differential mRNA expression of Amsacta moorei entomopoxvirus, mediated by the gene encoding a viral protein kinase (AMV197)

Insect-born entomopoxviruses (Fam: Poxviridae) are potentially important bio-pesticide against insect pests and expression vectors as well as vectors for transient human gene therapies including recombinant viral vaccines. For these reasons, it is necessary to understand the regulatory genes functions to improve its biotechnological potential. Here, we focused on the characterization of serine/threonine (Ser/Thr; ORF AMV197) protein kinase gene from the Amsacta moorei entomopoxvirus (AMEV), the type species of the genus Betaentomopoxvirus. Transcription of the parental and an amv197-null recombinant AMEV was compared by whole-genome gene expression microarray analysis. Blast2GO analysis reflected a broad diversity of upregulated and downregulated genes. Results showed that expression levels of 102 genes (45%) out of 226 tested genes changed significantly in the recombinant AMEV infected cells. Of these transcripts, 72 (70.58%) were upregulated and 30 (29.41%) were downregulated throughout the infection period. Genes involved in DNA repair, replication and nucleotide metabolism, transcription and RNA modification, and protein modification were mostly upregulated at different times in cells infected with the recombinant virus. Furthermore, transcription of all studied cellular genes including metabolism of apoptosis (Nedd2-like caspase, hemolin and elongation factor-1 alpha (ef1a) gene) was downregulated in the absence of amv197. Quantitative real time reverse transcription-PCR confirmed viral transcriptional changes obtained by microarray. The results of this study indicated that the product of amv197 appears to affect the transcriptional regulation of most viral and many cellular genes. Further investigations are, however, needed to narrow down the role of AMV197 throughout the infection process.

Human eukaryotic elongation factor 1A forms oligomers through specific cysteine residues

Eukaryotic elongation factor 1A (eEF1A) is a multifunctional protein involved in bundling actin, severing microtubule, activating the phosphoinositol-4 kinase, and recruiting aminoacyl-tRNAs to ribosomes during protein biosynthesis. Although evidence has shown the presence of the isoform eEF1A1 oligomers, the substantial mechanism of the self-association remains unclear. Herein, we found that human eEF1A1 could spontaneously form oligomers. Specifically, mutagenesis screen on cysteine residues demonstrated that Cys(234) was essential for eEF1A1 oligomerization. In addition, we also found that hydrogen peroxide treatment could induce the formation of eEF1A oligomers in cells. By cysteine replacement, eEF1A2 isoform displayed the ability to oligomerize in cells under the oxidative environment. In summary, in this study we characterized eEF1A1 oligomerization and demonstrated that specific cysteine residues are required for this oligomerization activity.

Elongation Factor 1A-1 Is a Mediator of Hepatocyte Lipotoxicity Partly through Its Canonical Function in Protein Synthesis

Elongation factor 1A-1 (eEF1A-1) has non-canonical functions in regulation of the actin cytoskeleton and apoptosis. It was previously identified through a promoter-trap screen as a mediator of fatty acid-induced cell death (lipotoxicity), and was found to participate in this process downstream of ER stress. Since ER stress is implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), we investigated the mechanism of action of eEF1A-1 in hepatocyte lipotoxicity. HepG2 cells were exposed to excess fatty acids, followed by assessments of ER stress, subcellular localization of eEF1A-1, and cell death. A specific inhibitor of eEF1A-1 elongation activity, didemnin B, was used to determine whether its function in protein synthesis is involved in lipotoxicity. Within 6 h, eEF1A-1 protein was modestly induced by high palmitate, and partially re-localized from its predominant location at the ER to polymerized actin at the cell periphery. This early induction and subcellular redistribution of eEF1A-1 coincided with the onset of ER stress, and was later followed by cell death. Didemnin B did not prevent the initiation of ER stress by high palmitate, as indicated by eIF2α phosphorylation. However, consistent with sustained inhibition of eEF1A-1-dependent elongation activity, didemnin B prevented the recovery of protein synthesis and increase in GRP78 protein that are normally associated with later phases of the response to ongoing ER stress. This resulted in decreased palmitate-induced cell death. Our data implicate eEF1A-1, and its function in protein synthesis, in hepatocyte lipotoxicity.

Critical role of eukaryotic elongation factor 1 alpha 1 (EEF1A1) in avian reovirus sigma-C-induced apoptosis and inhibition of viral growth

Avian reovirus (ARV) causes viral arthritis, chronic respiratory diseases, retarded growth and malabsorption syndrome. It is well established that the ARV sigma-C protein induces apoptosis in host cells. However, the underlying molecular mechanism of this induction is still unclear. We report here the identification of eukaryotic elongation factor 1 alpha 1 (EEF1A1) as the interacting partner of σC. We found that σC-induced apoptosis in DF-1 cells could be completely abolished by knockdown of EEF1A1 by siRNA. Furthermore, knockdown of EEF1A1 markedly reduced ARV-induced apoptosis associated with decreased caspase-9 and -3 activation and cytochrome C release, leading to increased ARV growth in host cells. Thus, EEF1A1 plays a critical role in σC-induced apoptosis and inhibition of viral growth.

The eEF1A Proteins: At the Crossroads of Oncogenesis, Apoptosis, and Viral Infections

Eukaryotic translation elongation factors 1 alpha, eEF1A1 and eEF1A2, are not only translation factors but also pleiotropic proteins that are highly expressed in human tumors, including breast cancer, ovarian cancer, and lung cancer. eEF1A1 modulates cytoskeleton, exhibits chaperone-like activity and also controls cell proliferation and cell death. In contrast, eEF1A2 protein favors oncogenesis as shown by the fact that overexpression of eEF1A2 leads to cellular transformation and gives rise to tumors in nude mice. The eEF1A2 protein stimulates the phospholipid signaling and activates the Akt-dependent cell migration and actin remodeling that ultimately favors tumorigenesis. In contrast, inactivation of eEF1A proteins leads to immunodeficiency, neural and muscular defects, and favors apoptosis. Finally, eEF1A proteins interact with several viral proteins resulting in enhanced viral replication, decreased apoptosis, and increased cellular transformation. This review summarizes the recent findings on eEF1A proteins indicating that eEF1A proteins play a critical role in numerous human diseases through enhancement of oncogenesis, blockade of apoptosis, and increased viral pathogenesis.

Proteomic analysis of liver in rats chronically exposed to fluoride

Fluoride (F) is a potent anti-cariogenic element, but when ingestion is excessive, systemic toxicity may be observed. This can occur as acute or chronic responses, depending on both the amount of F and the time of exposure. The present study identified the profile of protein expression possibly associated with F-induced chronic hepatotoxicity. Weanling male Wistar rats (three-weeks old) were divided into three groups and treated with drinking water containing 0, 5 or 50 mg/L F for 60 days (n=6/group). At this time point, serum and livers were collected for F analysis, which was done using the ion-sensitive electrode, after hexamethyldisiloxane-facilitated diffusion. Livers were also submitted to histological and proteomic analyses (2D-PAGE followed by LC-MS/MS). Western blotting was done for confirmation of the proteomic data A dose-response was observed in serum F levels. In the livers, F levels were significantly increased in the 50 mg/L F group compared to groups treated with 0 and 5 mg/L F. Liver morphometric analysis did not reveal alterations in the cellular structures and lipid droplets were present in all groups. Proteomic quantitative intensity analysis detected 33, 44, and 29 spots differentially expressed in the comparisons between control vs. 5 mg/L F, control vs. 50 mg/L F, and 5 mg/L vs. 50 mg/L F, respectively. From these, 92 proteins were successfully identified. In addition, 18, 1, and 5 protein spots were shown to be exclusive in control, 5, and 50 mg/L F, respectively. Most of proteins were related to metabolic process and pronounced alterations were seen for the high-F level group. In F-treated rats, changes in the apolipoprotein E (ApoE) and GRP-78 expression may account for the F-induced toxicity in the liver. This can contribute to understanding the molecular mechanisms underlying hepatoxicity induced by F, by indicating key-proteins that should be better addressed in future studies.

Eukaryotic translation elongation factor 1-alpha 1 inhibits p53 and p73 dependent apoptosis and chemotherapy sensitivity

The p53 family of transcription factors is a key regulator of cell proliferation and death. In this report we identify the eukaryotic translation elongation factor 1-alpha 1 (eEF1A1) to be a novel p53 and p73 interacting protein. Previous studies have demonstrated that eEF1A1 has translation-independent roles in cancer. We report that overexpression of eEF1A1 specifically inhibits p53-, p73- and chemotherapy-induced apoptosis resulting in chemoresistance. Short-interfering RNA-mediated silencing of eEF1A1 increases chemosensitivity in cell lines bearing wild type p53, but not in p53 null cells. Furthermore, silencing of eEF1A1 partially rescues the chemoresistance observed in response to p53 or p73 knockdown, suggesting that eEF1A1 is a negative regulator of the pro-apoptotic function of p53 and p73. Thus, in the context of p53-family signaling, eEF1A1 has anti-apoptotic properties. These findings identify a novel mechanism of regulation of the p53 family of proteins by eEF1A1 providing additional insight into potential targets to sensitize tumors to chemotherapy.

SSH gene expression profile of Eisenia andrei exposed in situ to a naturally contaminated soil from an abandoned uranium mine

The effects of the exposure of earthworms (Eisenia andrei) to contaminated soil from an abandoned uranium mine, were assessed through gene expression profile evaluation by Suppression Subtractive Hybridization (SSH). Organisms were exposed in situ for 56 days, in containers placed both in a contaminated and in a non-contaminated site (reference). Organisms were sampled after 14 and 56 days of exposure. Results showed that the main physiological functions affected by the exposure to metals and radionuclides were: metabolism, oxireductase activity, redox homeostasis and response to chemical stimulus and stress. The relative expression of NADH dehydrogenase subunit 1 and elongation factor 1 alpha was also affected, since the genes encoding these enzymes were significantly up and down-regulated, after 14 and 56 days of exposure, respectively. Also, an EST with homology for SET oncogene was found to be up-regulated. To the best of our knowledge, this is the first time that this gene was identified in earthworms and thus, further studies are required, to clarify its involvement in the toxicity of metals and radionuclides. Considering the results herein presented, gene expression profiling proved to be a very useful tool to detect earthworms underlying responses to metals and radionuclides exposure, pointing out for the detection and development of potential new biomarkers.

Proteome analysis of altered proteins in streptozotocin-induced diabetic rat kidney using the fluorogenic derivatization-liquid chromatography-tandem mass spectrometry method

To find new molecular markers for early diagnosis of diabetic nephropathy, we applied fluorogenic derivatization-liquid chromatography-tandem mass spectrometry to identify the differentially expressed proteins in the kidney of control and streptozotocin-induced diabetic rats. The Sprague-Dawley rats were injected with the sodium citrate buffer or streptozotocin and then killed after 1, 4, 12 and 24 weeks. The results showed that seven proteins were significantly changed after 1 week of injection. Only one protein had significantly changed after 4 weeks of injection. However, after 12 weeks of injection, the number of altered proteins rose to 10. After 24 weeks of injection, 18 proteins had altered significantly. Five common proteins were significantly altered at week 12 and 24 after injection, respectively. Importantly, these proteins appeared prior to microalbuminuria and may serve as new biomarkers that are able to improve early detection of and new drug development for diabetic-related nephropathy.

Regulation of translation by hydrogen peroxide

Cells must be able to maintain their intracellular homeostasis in the face of changing conditions. Typically, they respond by invoking complex regulatory mechanisms, including a global inhibition of translation. This reduction in protein synthesis may prevent continued gene expression during potentially error-prone conditions as well as allow for the turnover of existing mRNAs and proteins, whilst gene expression is directed toward the production of new molecules required to protect against or detoxify the stress. However, it is becoming increasingly recognized that not all translation is inhibited and translational control of specific mRNAs is required for survival under stress conditions. Control of protein levels via translational regulation offers a significant advantage to the cell due to the immediacy of the regulatory effect. This review describes how protein synthesis is regulated in response to oxidative stress conditions induced by exposure to hydrogen peroxide. Translational control can be mediated via direct oxidative regulation of translation factors as well via mRNA-specific regulatory mechanisms. Additionally, increasing evidence suggests that oxidative damage to the translational apparatus can itself alter the proteomic output. The resulting translational reprogramming is fundamental for adaptation to the oxidative stress.

Proteomic insight into phenolic adaptation of a moderately halophilicHalomonassp. strain AAD12

A gram-negative, moderately halophilic bacterium was isolated from Çamaltı Saltern area, located in the Aegean Region of Turkey. Analysis of its 16S rRNA gene sequence and physiological characteristics showed that this strain belonged to the genus Halomonas ; hence, it was designated as Halomonas sp. strain AAD12. The isolate tolerated up to 800 mg⋅L–1phenol; however, at elevated concentrations, phenol severely retarded cell growth. The increase in lag phase with increasing phenol concentrations indicated that the microorganism was undergoing serious adaptative changes. To understand the physiological responses of Halomonas sp. strain AAD12 to phenol, a 2-dimensional electrophoresis approach combined with mass spectrometric analysis was used. This approach showed that the expression of 14 protein spots were altered as phenol concentration increased from 200 to 800 mg⋅L–1. Among the identified proteins were those involved in protein biosynthesis, energy, transport, and stress metabolism. So far, this is the first study on phenolic adaptation of a gram-negative, moderately halophilic bacteria using proteomic tools. The results provided new insights for understanding the general mechanism used by moderately halophilic bacteria to tolerate phenol and suggested the potential for using these microorganisms in bioremediation.

Investigations of transcript expression in fathead minnow (Pimephales promelas) brain tissue reveal toxicological impacts of RDX exposure

Production, usage and disposal of the munitions constituent (MC) cyclotrimethylenetrinitramine (RDX) has led to environmental releases on military facilities. The chemical attributes of RDX are conducive for leaching to surface water which may put aquatic organisms at risk of exposure. Because RDX has been observed to cause aberrant neuromuscular effects across a wide range of animal phyla, we assessed the effects of RDX on central nervous system (CNS) functions in the representative aquatic ecotoxicological model species, fathead minnow (Pimephales promelas). We developed a fathead minnow brain-tissue cDNA library enriched for transcripts differentially expressed in response to RDX and trinitrotoluene (TNT) exposure. All 4,128 cDNAs were sequenced, quality filtered and assembled yielding 2230 unique sequences and 945 significant blastx matches (E ≤10(-5)). The cDNA library was leveraged to create custom-spotted microarrays for use in transcript expression assays. The impact of RDX on transcript expression in brain tissue was examined in fathead minnows exposed to RDX at 0.625, 2.5, 5, 10mg/L or an acetone-spike control for 10 days. Overt toxicity of RDX in fathead minnow occurred only at the highest exposure concentration resulting in 50% mortality and weight loss. Conversely, Bayesian analysis of microarray data indicated significant changes in transcript expression at concentrations as low as 0.625 mg/L. In total, 154 cDNAs representing 44 unique transcripts were differentially expressed in RDX exposures, the majority of which were validated by reverse transcriptase-quantitative PCR (RT-qPCR). Investigation of molecular pathways, gene ontology (GO) and individual gene functions affected by RDX exposures indicated changes in metabolic processes involved in: oxygen transport, neurological function, calcium binding/signaling, energy metabolism, cell growth/division, oxidative stress and ubiquitination. In total, our study indicated that RDX exposure affected molecular processes critical to CNS function in fathead minnow.

Identification and characterization of genes associated with tapping panel dryness from Hevea brasiliensis latex using suppression subtractive hybridization

BACKGROUND

Tapping panel dryness (TPD) is one of the most serious threats to natural rubber production. Although a great deal of effort has been made to study TPD in rubber tree, the molecular mechanisms underlying TPD remain poorly understood. Identification and systematical analyses of the genes associated with TPD are the prerequisites for elucidating the molecular mechanisms involved in TPD. The present study is undertaken to generate information about the genes related to TPD in rubber tree.

RESULTS

To identify the genes related to TPD in rubber tree, forward and reverse cDNA libraries from the latex of healthy and TPD trees were constructed using suppression subtractive hybridization (SSH) method. Among the 1106 clones obtained from the two cDNA libraries, 822 clones showed differential expression in two libraries by reverse Northern blot analyses. Sequence analyses indicated that the 822 clones represented 237 unique genes; and most of them have not been reported to be associated with TPD in rubber tree. The expression patterns of 20 differentially expressed genes were further investigated to validate the SSH data by reverse transcription PCR (RT-PCR) and real-time PCR analysis. According to the Gene Ontology convention, 237 unique genes were classified into 10 functional groups, such as stress/defense response, protein metabolism, transcription and post-transcription, rubber biosynthesis, etc. Among the genes with known function, the genes preferentially expressed were associated with stress/defense response in the reverse library, whereas metabolism and energy in the forward one.

CONCLUSIONS

The genes associated with TPD were identified by SSH method in this research. Systematic analyses of the genes related to TPD suggest that the production and scavenging of reactive oxygen species (ROS), ubiquitin proteasome pathway, programmed cell death and rubber biosynthesis might play important roles in TPD. Therefore, our results not only enrich information about the genes related to TPD, but also provide new insights into understanding the TPD process in rubber tree.

Studies on glyphosate-induced carcinogenicity in mouse skin: a proteomic approach

Glyphosate is a widely used broad spectrum herbicide, reported to induce various toxic effects in non-target species, but its carcinogenic potential is still unknown. Here we showed the carcinogenic effects of glyphosate using 2-stage mouse skin carcinogenesis model and proteomic analysis. Carcinogenicity study revealed that glyphosate has tumor promoting activity. Proteomic analysis using 2-dimensional gel electrophoresis and mass spectrometry showed that 22 spots were differentially expressed (>2 fold) on glyphosate, 7, 12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) application over untreated control. Among them, 9 proteins (translation elongation factor eEF-1 alpha chain, carbonic anhydrase III, annexin II, calcyclin, fab fragment anti-VEGF antibody, peroxiredoxin-2, superoxide dismutase [Cu-Zn], stefin A3, and calgranulin-B) were common and showed similar expression pattern in glyphosate and TPA-treated mouse skin. These proteins are known to be involved in several key processes like apoptosis and growth-inhibition, anti-oxidant responses, etc. The up-regulation of calcyclin, calgranulin-B and down-regulation of superoxide dismutase [Cu-Zn] was further confirmed by immunoblotting, indicating that these proteins can be good candidate biomarkers for skin carcinogenesis induced by glyphosate. Altogether, these results suggested that glyphosate has tumor promoting potential in skin carcinogenesis and its mechanism seems to be similar to TPA.

The interaction between interferon-induced protein with tetratricopeptide repeats-1 and eukaryotic elongation factor-1A

It has been shown previously that in mammalian cells, interferon-induced protein with tetratricopeptide repeats-1(IFIT1) is rapidly synthesized in response to viral infection, functions as an inhibitor of translation by binding to the eukaryotic initiation factor-3, and consequently assigns resistive activity against viral invasion to cells. It has also been reported that IFIT1 is rapidly produced in response to other cell stress agents with no direct relation to virus such as bacterial lipopolysaccharide and interleukin-1, but its function under these non-viral infection cell stress conditions has yet to be elucidated. Here, we demonstrate an interaction between IFIT1 and eukaryotic elongation factor-1A (eEF1A) both in vitro, using recombinant proteins as bait in pull-down assays, and in vivo, using laser confocal microscopy and immunoprecipitation. In addition, we report the initial determination of the domain of IFIT1 that mediates this interaction. We also display that both IFIT1 and eEF1A protein levels are rapidly elevated, prolonged in tumor necrosis factor alpha pre-treated Raw264.7 cells, and most of those cells are induced to death by the end of investigations. Our results imply that under some stressful stimulations IFIT1 may participate in cell death pathways by interaction with eEF1A.

Something old, something new, something borrowed; how the thermoacidophilic archaeon Sulfolobus solfataricus responds to oxidative stress

To avoid molecular damage of biomolecules due to oxidation, all cells have evolved constitutive and responsive systems to mitigate and repair chemical modifications. Archaea have adapted to some of the most extreme environments known to support life, including highly oxidizing conditions. However, in comparison to bacteria and eukaryotes, relatively little is known about the biology and biochemistry of archaea in response to changing conditions and repair of oxidative damage. In this study transcriptome, proteome, and chemical reactivity analyses of hydrogen peroxide (H(2)O(2)) induced oxidative stress in Sulfolobus solfataricus (P2) were conducted. Microarray analysis of mRNA expression showed that 102 transcripts were regulated by at least 1.5 fold, 30 minutes after exposure to 30 microM H(2)O(2). Parallel proteomic analyses using two-dimensional differential gel electrophoresis (2D-DIGE), monitored more than 800 proteins 30 and 105 minutes after exposure and found that 18 had significant changes in abundance. A recently characterized ferritin-like antioxidant protein, DPSL, was the most highly regulated species of mRNA and protein, in addition to being post-translationally modified. As expected, a number of antioxidant related mRNAs and proteins were differentially regulated. Three of these, DPSL, superoxide dismutase, and peroxiredoxin were shown to interact and likely form a novel supramolecular complex for mitigating oxidative damage. A scheme for the ability of this complex to perform multi-step reactions is presented. Despite the central role played by DPSL, cells maintained a lower level of protection after disruption of the dpsl gene, indicating a level of redundancy in the oxidative stress pathways of S. solfataricus. This work provides the first "omics" scale assessment of the oxidative stress response for an archeal organism and together with a network analysis using data from previous studies on bacteria and eukaryotes reveals evolutionarily conserved pathways where complex and overlapping defense mechanisms protect against oxygen toxicity.

Fibroblast protein profile analysis highlights the role of oxidative stress and vitamin K recycling in the pathogenesis of pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a genetic disorder associated to mutations in the ABCC6 gene; however, the pathogenetic mechanisms leading to elastic fibre calcifications and to clinical manifestations are still unknown. Dermal fibroblasts, directly involved in the production of the extracellular milieu, have been isolated from healthy subjects and from patients affected by PXE, cultured in vitro and characterized for their ability to produce reactive oxygen species, for structural and functional properties of their cell membranes, for changes in their protein profile. Data demonstrate that oxidative stress has profound and endurable consequences on PXE fibroblast phenotype being responsible for: reduced levels of global DNA methylation, increased amount of carbonylated proteins and of lipid peroxidation products, altered structural properties of cell membranes, modified protein expression. Data shed new light on the pathogenetic pathways in PXE, by identifying a network of proteins affecting elastic fibre calcification through inefficient vitamin K recycling, and highlight the role of differentially expressed proteins as targets for validating the efficacy of future therapeutic strategies aiming to delay and/or revert the pathologic phenotype of PXE fibroblasts. Moreover, data open new perspectives for investigating PXE-like phenotypes in the absence of ABCC6 mutations.

The SAM domain of the RhoGAP DLC1 binds EF1A1 to regulate cell migration

Deleted in liver cancer 1 (DLC1) is a multi-modular Rho-GTPase-activating protein (RhoGAP) and a tumor suppressor. Besides its RhoGAP domain, functions of other domains in DLC1 remain largely unknown. By protein precipitation and mass spectrometry, we identified eukaryotic elongation factor 1A1 (EF1A1) as a novel partner for the sterile alpha motif (SAM) domain of DLC1 but not the SAM domain of DLC2. The solution structure of DLC1 SAM revealed a new monomeric fold with four parallel helices, similar to that of DLC2 SAM but distinct from other SAM domains. Mutating F38, L39 and F40 within a hydrophobic patch retained its overall structure but abolished its interaction with EF1A1 with F38 and L39 forming an indispensable interacting motif. DLC1 SAM did not localize to and was not required for DLC1 to suppress the turnover of focal adhesions. Instead, DLC1 SAM facilitated EF1A1 distribution to the membrane periphery and ruffles upon growth factor stimulation. Compared with wild-type DLC1, the non-interactive DLC1 mutant is less potent in suppressing cell migration, whereas overexpression of the DLC1 SAM domain alone, but not the non-interactive mutant SAM or DLC2 SAM, greatly enhanced cell migration. This finding reveals a novel contribution of the SAM-EF1A1 interaction as a potentially important GAP-independent modulation of cell migration by DLC1.

Proteomic analysis of anoxia tolerance in the developing zebrafish embryo

While some species and tissue types are injured by oxygen deprivation, anoxia tolerant organisms display a protective response that has not been fully elucidated and is well-suited to genomic and proteomic analysis. However, such methodologies have focused on transcriptional responses, prolonged anoxia, or have used cultured cells or isolated tissues. In this study of intact zebrafish embryos, a species capable of >24 h survival in anoxia, we have utilized 2D difference in gel electrophoresis to identify changes in the proteomic profile caused by near-lethal anoxic durations as well as acute anoxia (1 h), a timeframe relevant to ischemic events in human disease when response mechanisms are largely limited to post-transcriptional and post-translational processes. We observed a general stabilization of the proteome in anoxia. Proteins involved in oxidative phosphorylation, antioxidant defense, transcription, and translation changed over this time period. Among the largest proteomic alterations was that of muscle cofilin 2, implicating the regulation of the cytoskeleton and actin assembly in the adaptation to acute anoxia. These studies in an intact embryo highlight proteomic components of an adaptive response to anoxia in a model organism amenable to genetic analysis to permit further mechanistic insight into the phenomenon of anoxia tolerance.

Molecular characterization and expression analysis of five different elongation factor 1 alpha genes in the flatfish Senegalese sole (Solea senegalensis Kaup): differential gene expression and thyroid hormones dependence during metamorphosis

BACKGROUND

Eukaryotic elongation factor 1 alpha (eEF1A) is one of the four subunits composing eukaryotic translation elongation factor 1. It catalyzes the binding of aminoacyl-tRNA to the A-site of the ribosome in a GTP-dependent manner during protein synthesis, although it also seems to play a role in other non-translational processes. Currently, little information is still available about its expression profile and regulation during flatfish metamorphosis. With regard to this, Senegalese sole (Solea senegalensis) is a commercially important flatfish in which eEF1A gene remains to be characterized.

RESULTS

The development of large-scale genomics of Senegalese sole has facilitated the identification of five different eEF1A genes, referred to as SseEF1A1, SseEF1A2, SseEF1A3, SseEF1A4, and Sse42Sp50. Main characteristics and sequence identities with other fish and mammalian eEF1As are described. Phylogenetic and tissue expression analyses allowed for the identification of SseEF1A1 and SseEF1A2 as the Senegalese sole counterparts of mammalian eEF1A1 and eEF1A2, respectively, and of Sse42Sp50 as the ortholog of Xenopus laevis and teleost 42Sp50 gene. The other two elongation factors, SseEF1A3 and SseEF1A4, represent novel genes that are mainly expressed in gills and skin. The expression profile of the five genes was also studied during larval development, revealing different behaviours. To study the possible regulation of SseEF1A gene expressions by thyroid hormones (THs), larvae were exposed to the goitrogen thiourea (TU). TU-treated larvae exhibited lower SseEF1A4 mRNA levels than untreated controls at both 11 and 15 days after treatment, whereas transcripts of the other four genes remained relatively unchanged. Moreover, addition of exogenous T4 hormone to TU-treated larvae increased significantly the steady-state levels of SseEF1A4 with respect to untreated controls, demonstrating that its expression is up-regulated by THs.

CONCLUSION

We have identified five different eEF1A genes in the Senegalese sole, referred to as SseEF1A1, SseEF1A2, SseEF1A3, SseEF1A4, and Sse42Sp50. The five genes exhibit different expression patterns in tissues and during larval development. TU and T4 treatments demonstrate that SseEF1A4 is up-regulated by THs, suggesting a role in the translational regulation of the factors involved in the dramatic changes that occurs during Senegalese sole metamorphosis.

Overexpression of the elongation factor 1A1 relates to muscle proteolysis and proapoptotic p66(ShcA) gene transcription in hypercatabolic trauma patients

The eukaryotic elongation factors (eEF1A2 and eEF1A1) play a key role in translation of messenger RNA (mRNA) to protein. In skeletal muscle of healthy humans, EEF1A2 is overexpressed and selected over EEF1A1. In cellular stress models, muscle EEF1A1 expression increased and was associated with apoptosis and catabolism. We have determined mRNA levels of EEF1A1 and EEF1A2, as well as those of other proapoptotic genes, such as p66(ShcA) and c-MYC, in skeletal muscle of severely traumatized patients and healthy volunteers. Muscle protein kinetic was determined by stable isotopes and the arteriovenous technique. The patients were in a hypercatabolic condition because the rate of muscle proteolysis exceeded that of synthesis. Mean mRNA levels of EEF1A1 and EEF1A2 were 165- and 29-fold greater (P < .01) in patients than in the control group, respectively. Mean p66(ShcA) mRNA levels were 3-fold greater (P < .05) in patients than in the controls. In contrast, c-MYC mRNA levels were not significantly different in patients and healthy controls. In patients, muscle mRNA levels of EEF1A1 and p66(ShcA) directly correlated (P < .05) with the rate of proteolysis (R = 0.901 and R = 0.826, respectively). This is in agreement with a reduction in actin and tubulin protein content, both markers of cytoskeletal and sarcomeric disorganization, and with an increased poly(adenosine diphosphate-ribose) polymerase cleavage, a marker of apoptosis. In conclusion, in hypercatabolic traumatized patients, an up-regulation of muscle EEF1A1 and p66(ShcA) relates to proteolysis rate, suggesting an involvement of these genes in muscle catabolic response.

Scythe regulates apoptosis through modulating ubiquitin-mediated proteolysis of the Xenopus elongation factor XEF1AO

Scythe was originally identified as a novel Reaper-binding anti-apoptotic protein, although the mechanisms of its functions remain largely obscure. Our previous analysis revealed that Scythe can bind to a proteasomal subunit via N-terminal domains and that the domains are required for appropriate development of Xenopus embryos. In the present study, we show evidence that the N-terminus of Scythe interacts with XEF1AO, a maternal form of Xenopus laevis EF1A that was suggested to be a potential inducer of apoptosis in vertebrates, and that the binding enhances the poly-ubiquitin modification and subsequent degradation of XEF1AO. Scythe is required for degradation of XEF1AO, since immunodepletion of Scythe from embryonic extracts stabilized XEF1AO significantly. Furthermore, we show that apoptosis induced by accumulation of XEF1AO can be suppressed by co-expression of the full-length form of Scythe. These observations indicate that the proteolytic regulation of XEF1AO, mediated through Scythe, is essential to prevent inappropriate accumulation of XEF1AO and resulting apoptotic events during the course of Xenopus development.

C-Raf antagonizes apoptosis induced by IFN-α in human lung cancer cells by phosphorylation and increase of the intracellular content of elongation factor 1A

Interferon alpha (IFNalpha) induces both apoptosis and a counteracting epidermal growth factor Erk-dependent survival response in cancer cells. In this report, IFNalpha increased eukaryotic elongation factor 1A (eEF-1A) protein expression by inhibition of eEF-1A degradation via a proteasome-dependent pathway. The reduction of the expression level of eEF-1A by RNA interference enhanced the apoptosis induced by IFNalpha on the same cells. Moreover, IFNalpha induced the phosphorylation of both serine and threonine in eEF-1A. These effects were paralleled by an increased co-immunoprecipitation and colocalization of eEF-1A with C-Raf. The suppression of C-Raf kinase activity with the inhibitor BAY 43-9006 completely antagonized the increase of both eEF-1A phosphorylation and expression and of C-Raf/eEF-1A colocalization induced by IFNalpha and enhanced apoptosis and eEF-1A ubiquitination. Cell transfection with the mutated K48R ubiquitin increased EF-1A expression and desensitized tumor cells to the modulating effects of IFNalpha. The dynamic simulation of 3Dstructure of eEF-1A identified putative serine and threonine phosphorylation sites. In conclusion, the interaction between eEF-1A and C-Raf increases eEF-1A stability and induces a survival activity.