The growth-related, translationally controlled protein P23 has properties of a tubulin binding protein and associates transiently with microtubules during the cell cycle

Potato skin proteome is enriched with plant defence components

Periderm is a tissue of secondary origin that replaces damaged epidermis. It can be found in underground plant organs, as an above-ground tissue of woody species (cork), and as a wound-healing tissue. Its outer layers are composed of phellem cells with suberized walls that constitute a protective barrier, preventing pathogen invasion and fluid loss. In potato, a model for periderm studies, periderm tissue replaces the epidermis early in tuber development and the suberized phellems constitute the tuber's skin. To identify factors involved in phellem/skin development and that play a role in its defensive characteristics, two-dimensional gel electrophoresis was used to compare the skin and parenchymatic flesh proteomes of young developing tubers. Proteins exhibiting differentially high signal intensity in the skin were sorted by functional categories. As expected, the differential skin proteome was enriched in proteins whose activity is characteristic of actively dividing tissues such as cell proliferation, C(1) metabolism, and the oxidative respiratory chain. Interestingly, the major functional category consisted of proteins (63%) involved in plant defence responses to biotic and abiotic stresses. This group included three isozymes of caffeoyl-CoA O-methyltransferase and five isozymes of peroxidase that may play a role in suberization processes. The differential expression of these proteins in the skin was further verified by RT-PCR of their corresponding transcripts in skin and tuber flesh samples. The results presented here shed light on the early events in skin development and further expand the concept of the periderm as a protective tissue containing an array of plant defence components.

The salivary glands and saliva of Anopheles gambiae as an essential step in the Plasmodium life cycle: a global proteomic study

Proteins synthesized in the salivary glands of the Anopheles gambiae mosquito are thought to be important in the life cycle of the malaria parasite Plasmodium. To describe A. gambiae salivary gland and saliva contents, we combined several techniques: 1-DE, 2-DE and LC MS/MS. This study has identified five saliva proteins and 122 more proteins from the salivary glands, including the first proteomic description for 89 of these salivary gland proteins. Since the invasion and sporozoite maturation take place during the process of salivary glands ageing, the effect of salivary gland age on salivary component composition was examined. LC MS/MS profiling of young versus old salivary gland proteomes suggests that there is an over-representation of proteins involved in signaling and proteins related to the immune response in the proteins from older mosquitoes. The iTRAQ labeling was used for a comparative proteomic analysis of salivary gland samples from infected or Plasmodium berghei-free mosquitoes. The expression levels of five secreted proteins were altered when the parasite was present. These observations will serve as a basis for future work concerning the possible role of these proteins in the interaction between A. gambiae, Plasmodium and the mammalian host.

Translationally controlled tumor protein of Brugia malayi functions as an antioxidant protein

Translationally controlled tumor protein (TCTP) is one of the most abundantly expressed proteins in the filarial parasites as well as in the other organisms. Several functions have been suggested for TCTP family of proteins ranging from calcium binding to histamine release function. However, its physiological function is still a mystery. Previous studies showed that the expression of TCTP is increased several-fold during oxidative stress. In the present work, we report the putative antioxidant function of Brugia malayi TCTP (BmTCTP). When tested in vitro, rBmTCTP could be reduced by a variety of reducing agents including thioredoxin. Such reduced form of rBmTCTP was able to protect DNA from oxidative damage, suggesting that BmTCTP may have an antioxidant function in the parasite. Sequence analysis of filarial TCTPs revealed that there are three cysteine amino acids located in the central portion of the protein. Subsequent targeted residue modification studies showed that these cysteine residues in rBmTCTP are critical for its antioxidant function. To determine the significance of this finding, rBmTCTP was overexpressed in vivo in Escherichia coli and subjected to oxidative stress. These studies showed that rBmTCTP significantly protected cells form oxidative damage. Taken together, these findings suggest that BmTCTP might be functioning as a non-classical antioxidant protein in the filarial parasites.

Protein changes in the albedo of citrus fruits on postharvesting storage

In this work, major protein changes in the albedo of the fruit peel of Murcott tangor (tangerine x sweet orange) during postharvest ageing were studied through 2D PAGE. Protein content in matured on-tree fruits and in fruits stored in nonstressing [99% relative humidity (RH) and 25 degrees C], cold (99% RH and 4 degrees C), and drought (60% RH and 25 degrees C) conditions was initially determined. Protein identification through MS/MS determinations revealed in all samples analyzed the occurrence of manganese superoxide dismutase (Mn SOD), actin, ATP synthase beta subunit (ATPase), citrus salt-stress associated protein (CitSap), ascorbate peroxidase (APX), translationally controlled tumor protein (TCTP), and a cysteine proteinase (CP) of the papain family. The latter protein was identified in two different gel spots, with different molecular mass, suggesting the simultaneous presence of the proteinase precursor and its active form. While Mn SOD, actin, ATPase, and CitSap were unchanged in the assayed conditions, TCTP and APX were downregulated during the postharvest ageing process. Ageing-induced APX repression was also reversed by drought. CP contents in albedo, which were similar in on- and off-tree fruits, were strongly dependent upon cold storage. The active/total CP protein ratio significantly increased after cold exposure. This proteomic survey indicates that major changes in protein content in the albedo of the peel of postharvest stored citrus fruits are apparently related to the activation of programmed cell death (PCD).

Induction of translationally controlled tumor protein (TCTP) by transcriptional and post-transcriptional mechanisms

Expression of the human TPT1 gene coding for translationally controlled tumor protein (TCTP) was investigated in Calu-6 and Cos-7 cells under the influence of 4beta-phorbol 12-myristate 13-acetate (PMA), forskolin, dioxin and the heavy metals copper, nickel and cobalt. Transcriptional and post-transcriptional aspects of the mechanism were analyzed by TCTP mRNA/protein quantification, luciferase reporter gene assays depending on TPT1 promoter sequences or TCTP mRNA 5'/3'-UTRs and investigation of the interaction of RNA-binding proteins with UTRs by UV-crosslinking. PMA, forskolin, dioxin, cobalt and nickel induced TCTP expression in 24 h in both cell lines about 2.2-3.2-fold at the mRNA level and 1.6-2.2-fold at the protein level. The highest induction rate, 4.5-5.0-fold at the mRNA level and 3.5-4.0-fold at the protein level, was observed with copper. TPT1 promoter assays showed transcriptional activation by PMA, forskolin and dioxin (2.0-3.1-fold) and a 7.0-8.0-fold increase by copper, whereas cobalt and nickel had no effect. Deletion analysis revealed that copper-dependent transcriptional control was transmitted by a metal-responsive element residing in the TPT1 promoter. Post-transcriptional activation of TCTP expression was associated with the action of dioxin, nickel, cobalt (1.8-2.3-fold) and copper (2.5-3.0-fold), whereas stimulation of TCTP synthesis by copper was mediated by the TCTP mRNA 3'-UTR (3.2-fold) but not by the 5'-UTR (0.5-fold). mRNA stabilization was found to mediate these effects of cobalt and nickel. Post-transcriptional regulation was associated with qualitative and quantitative changes in the binding of specific RNA-binding proteins to UTRs.

Solution structure and mapping of a very weak calcium-binding site of human translationally controlled tumor protein by NMR

Human translationally controlled tumor protein (TCTP) is a growth-related, calcium-binding protein. We determined the solution structure and backbone dynamics of human TCTP, and identified the calcium-binding site of human TCTP using multi-dimensional NMR spectroscopy. The overall structure of human TCTP has a rather rigid well-folded core and a very flexible long loop connected by a short two-strand beta-sheet, which shows a conserved fold in the TCTP family. The C-terminal portions of loop L(alpha3beta8) and strand beta9 and the N-terminal region of strand beta8 may form a calcium-binding site in the human TCTP structure, which is largely conserved in the sequence alignment of TCTPs. The K(d) value for the calcium binding is 0.022-0.025 M indicating a very weak calcium-binding site.

Effect of folic acid on prenatal alcohol-induced modification of brain proteome in mice

Maternal alcohol consumption during pregnancy can induce central nervous system abnormalities in the fetus, and folic acid supplementation can reverse some of the effects. The objective of the present study was to investigate prenatal alcohol exposure-induced fetal brain proteome alteration and the protective effect of folic acid using proteomic techniques. Alcohol (5.0 g/kg) was given intragastrically from gestational day (GD) 6 to 15, with or without 60.0 mg folic acid/kg given intragastrically during GD 1-16 to pregnant Balb/c mice. The control group received distilled water only. Results of litter evaluation on GD 18 showed that supplementation of folic acid reversed the prevalence of microcephaly induced by alcohol. Proteomic analysis indicated that, under the dosage of the present investigation, folic acid mainly reversed the alcohol-altered proteins involved in energy production, signal pathways and protein translation, which are all important for central nervous system development.

Cladosporium herbarum translationally controlled tumor protein (TCTP) is an IgE-binding antigen and is associated with disease severity

Cladosporium herbarum represents one of the most important world-wide occurring allergenic fungal species. The prevalence of IgE reactivity to C. herbarum in patients suffering from allergy varies between 5 and 30% in the different climatic zones. Since mold allergy has often been associated with severe asthma, along with other allergic symptoms, it is important to define more comprehensively the allergen repertoire of this ascomycete. In this context we are reporting our successful approach to identify, clone, produce as a recombinant protein, purify and further characterize a new C. herbarum allergen which is a close homolog of the human translationally controlled tumor protein (TCTP, also called histamine releasing factor, HRF). The immunoreactivity of both pure recombinant molecules was investigated by means of immunoblot analyses, enzyme-linked immunosorbent assays as well as histamine release studies. To summarize, IgE antibodies from five out of nine individuals recognized both the human and the fungal protein in immunoblots. The latter was able to cause histamine release from human basophils with about half the efficiency compared to its human homolog HRF. Cross-inhibition assays showed that the patients' IgEs recognize common epitopes on both the human and C. herbarum proteins, but however, only pre-incubation with C. herbarum TCTP could completely inhibit reactivity with HRF. Furthermore, it appears that patients reactive to TCTP have a higher probability to suffer from asthma than other allergic patients.

Molecular coordinated regulation of gene expression during ovarian development in the penaeid shrimp

To understand the molecular events of ovarian development in penaeid shrimp, RNA arbitrarily primed polymerase chain reaction (RAP-PCR) was used to identify differentially expressed genes during ovarian maturation in Metapenaeus ensis. From a screening of 700 clones in a cDNA library of the shrimp ovary by the products of RAP-PCR of different maturation stages, 91 fragments with differentially expressed pattern as revealed by dot-blot hybridization were isolated and sequenced. Forty-two of these fragments show significant sequence similarity to known gene products and the differentially expressed pattern of 10 putative genes were further characterized via Northern hybridization. Putative glyceraldehyde-3-phosphate dehydrogenase and arginine kinase are related to provision of energy for active cellular function in oocyte development. Translationally controlled tumor protein, actin, and keratin are related to the organization of cytoskeleton to accomplish growth and development of oocytes. High mobility group protein DSP1, heat shock protein 70, and nucleoside diphosphate kinase may act as repressors before the onset of ovarian maturation. Peptidyl-prolyl cis-trans isomerase and glutathione peroxidase are related to the stabilization of proteins and oocytes. This study provides new insights on the molecular events in the ovarian development in the shrimp.

Evaluation of hepatitis B virus replication and proteomic analysis of HepG2.2.15 cell line after cyclosporine A treatment

AIM

The effect of cyclosporine A (CsA) on hepatitis B virus (HBV) replication was investigated, and proteomics expression differentiation after CsA treatment was studied in order to provide clues to explore the effect of CsA on HBV replication.

METHODS

Methyl thiazolyl tetrazolium (MTT) assay was used to evaluate the cytotoxicity of CsA. The HBV replication level in the HBV genomic DNA transfected HepG2.2.15 cell line was determined by an ELISA analysis of hepatitis B surface antigens (HBsAg) and Hepatitis B e antigens (HBeAg) in culture supernatant, while the intracellular HBV DNA replication level was analyzed by slot blot hybridization. Two-dimensional electrophoresis was used to investigate the alteration of protein expression in HepG2.2.15 after CsA treatment in vitro. The differentially-expressed proteins were identified by Matrix-assisted laser desorption/ionization-time of flight mass spectrometry combined with an online database search.

RESULTS

CsA was able to inhibit the expression of HBsAg, HBeAg, and HBV DNA replication in vitro in a dose-dependent manner. A proteomics analysis indicated that the expression of 17 proteins changed significantly in the CsA treatment group compared to the control group. Eleven of the 17 proteins were identified, including the overexpression of eukaryotic translation initiation factors (eIF) 3k, otubain 1, 14.3.3 protein, eIF2-1 alpha, eIF5A, and the tyrosine 3/tryptophan 5-mono-oxygenase activation protein in CsA-treated HepG2.2.15 cells. The downregulation of the ferritin light subunit, erythrocyte cytosolic protein of 51 kDa (ECP-51), stathmin 1/oncoprotein, adenine phosphoribosyl-transferase, and the position of a tumor protein, translationally controlled 1, was shifted, suggesting it had undergone posttranslational modifications.

CONCLUSION

Our study identified the inhibitory effect of CsA on HBV replication, and found that a group of proteins may be responsible for this inhibitory effect.

A knockout mouse approach reveals that TCTP functions as an essential factor for cell proliferation and survival in a tissue- or cell type-specific manner

Translationally controlled Tumor Protein (TCTP) is an evolutionally highly conserved protein which has been implicated in many cellular functions that are related to cell growth, death, and even the allergic response of the host. To address the physiological roles of TCTP, we generated TCTP knockout mice by targeted gene disruption. Heterozygous mutants appeared to be developmentally normal. However, homozygous mutants (TCTP(-/-)) were embryonic lethal. TCTP(-/-) embryos were smaller in size than the control littermates at all postimplantation stages examined. Although TCTP is widely expressed in both extraembryonic and embryonic tissues, the most prominent defect of the TCTP(-/-) embryo at embryonic stage day 5.5 (E5.5) was in its epiblast, which had a reduced number of cells compared with wild-type controls. The knockout embryos also suffered a higher incidence of apoptosis in epiblast starting about E6.5 and subsequently died around E9.5-10.5 with a severely disorganized structure. Last, we demonstrated that TCTP(-/-) and control mouse embryonic fibroblasts manifested similar proliferation activities and apoptotic sensitivities to various death stimuli. Taken together, our results suggest that despite that TCTP is widely expressed in many tissues or cell types, it appears to regulate cell proliferation and survival in a tissue- or cell type-specific manner.

Yeast apoptosis—From genes to pathways

Yeast are eukaryotic unicellular organisms that are easy to cultivate and offer a wide spectrum of genetic and cytological tools for research. Yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have successfully been used as models for human cell division cycle. Stress conditions, cellular ageing, failed mating, certain mutations or heterologous expression of proapoptotic genes induce yeast cell death with the characteristic markers of apoptosis. Several crucial regulators of apoptosis are conserved between metazoans and yeast. This simple model organism offers the possibility to identify conserved and new components of the apoptotic machinery and to elucidate the regulatory pathways beyond.

The expression of AmphiTCTP, a TCTP orthologous gene in amphioxus related to the development of notochord and somites

The translationally controlled tumor protein (TCTP) is highly conserved and has been widely found in eukaryotic organisms. Here, we report the phylogenetic analysis and developmental expression of AmphiTCTP, a TCTP homologous gene in cephalochordate amphioxus. Phylogenetic analysis indicates that the putative protein of AmphiTCTP is close to its vertebrate orthologs. The mRNA of AmphiTCTP is found in fertilized eggs, early cleavage embryo and most of the early developmental stages by in situ hybridization and RT-PCR, but its expression is not detectable from late cleavage stage to mid-gastrula. The expression of AmphiTCTP in zygotes and early cleavage stages shows that AmphiTCTP may be a maternal gene. From the early neurula stage onward, AmphiTCTP transcript is localized in the presumptive notochord, presomitic mesoderm, and nascent somites. However, its expression is gradually down-regulated after the notochord and somites have been formed. The expression pattern of AmphiTCTP thus coincides with the differentiation of the notochord and somites, this suggests that AmphiTCTP may not be a housekeeping gene and may play an important role in mesoderm development.

Proteomic Analysis of the Effects of Tetramethylpyrazine on Irradiated QXMSC1 Cells

Tetramethylpyrazine is the active ingredient of a Chinese herbal medicine. In this study, tetramethylpyrazine was tested for its activities in irradiated bone marrow stromal QXMSC1 cells. The proliferation of QXMSC1 cells was measured by MTS assay kit and flow cytometry. To identify proteins involved in the processes of cellular and molecular response of tetramethylpyrazine to irradiation damage, we comparatively analyzed the proteome of nonirradiated, irradiated and tetramethylpyrazine treated QXMSC1 cells. Reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins. 20 Gy 60Co gamma irradition inhibited QMSC1 cells growth and tetramethylpyrazine could reverse of this action due to stimulating QXMSC1 cells from G1 to S progression. Proteomic analytical results showed that 18 spots were changed in irradiated QXMSC1 cells, and 15 spots matched with known proteins after database searching. The expression level of proteins such as translationally controlled tumor protein (TCTP), and galectin-3, were increased in irradiated QXMSC1 cells, while calmodulin, pyruvate kinase were decreased. Tetramethylpyrazine could prevent this change or reverse to some degree. The function of these proteins involves in hematopoiesis, cell cycle and signal transduction. The changes of these proteins were confirmed by RT-PCR at mRNA levels. This study suggested that stimulating proliferation via tetramethylpyrazine played an important role in the cure effect on irradiated QXMSC1 cells and was helpful to deeply understand the mechanism of tetramethylpyrazine at the molecular level.

Proteomic profiling of murine oocyte maturation

In an effort to better understand oocyte function, we utilized two-dimensional (2D) electrophoresis and mass spectrometry to identify proteins that are differentially expressed during murine oocyte maturation. Proteins from 500 germinal vesicle (GV) and metaphase II-(MII) arrested oocytes were extracted, resolved on 2D electrophoretic gels, and stained with silver. Analysis of the gels indicated that 12 proteins appeared to be differentially expressed between the GV and MII stage. These proteins were then cored from the 2D gels and identified by mass spectrometry as: transforming acidic coiled-coil protein 3 (TACC3), heat shock protein 105 (HSP105), programmed cell death six-interacting protein (PDCD6IP), stress-inducible phosphoprotein (STI1), importin alpha2, adenylsuccinate synthase (ADDS), nudix, spindlin, lipocalin, lysozyme, translationally controlled tumor protein (TCTP), and nucleoplasmin 2 (NPM2). Interestingly, PDCD6IP, importin alpha2, spindlin, and NPM2 appear slightly larger in mass and more acidic on the MII oocyte gel compared to the GV oocyte gel, suggesting that they may be post-translationally modified during oocyte maturation. Given NPM2 is an oocyte-restricted protein, we chose to further investigate its properties during oocyte maturation and preimplantation development. Real-Time RT-PCR showed that NPM2 mRNA levels rapidly decline at fertilization. Indirect immunofluorescence analysis showed that, with the exception of cortical localization in MII-arrested oocytes, NPM2 is localized to the nucleus of both GV stage oocytes and all stages of preimplantation embryos. We then performed one-dimensional (1D) western blot analysis of mouse oocytes and preimplantation embryos and found that, as implicated by the 2D gel comparison, NPM2 undergoes a phosphatase-sensitive electrophoretic mobility shift during the GV to MII transition. The slower migrating NPM2 form is also present in pronuclear embryos but by the two-cell stage, the majority of NPM2 exists as the faster migrating form, which persists to the blastocyst stage.

Identification of AGE-modified proteins in SH-SY5Y and OLN-93 Cells

The formation of "Advanced Glycation End products" (AGEs) is an inevitable consequence of mammalian glucose metabolism. AGE-mediated protein-protein crosslinks lead to detergent-insoluble and protease-resistant protein aggregates, and in Alzheimer's disease (AD) extra cellular senile plaques (SPs) and intracellular neurofibrillary tangles (NFTs) have been shown to contain AGEs. However, to date little is known concerning the most prevalent protein-targets of AGE modification under normal, non-pathological conditions. Here, a combination of 2D-electrophoresis, Western blotting and mass spectrometry has been used to identify preferentially AGE-modified proteins in oligodendrocyte (OLN-93) and neuroblastoma cell lines (SH-SY5Y) in standard culture. Proteomics analysis identified a total of eight targets with structural, metabolic and regulatory function, three of which (beta-actin, beta-tubulin and eukaryotic Elongation Factor 1-alpha) were common to both cell lines. Based on results from prior studies, modification of these proteins may lead to a loss of function. Consequently, the identification of targets for these proteins is of particular interest for a better understanding of the consequences of AGE-modification in aging, neurodegenerative diseases and diabetes.

Proteomic Identification of Altered Proteins in Skeletal Muscle During Chronic Potassium Depletion: Implications for Hypokalemic Myopathy

Prolonged potassium depletion is a well-known cause of myopathy. The pathophysiology of hypokalemic myopathy, however, remains unclear. We performed a gel-based, differential proteomics study to define altered proteins in skeletal muscles during chronic potassium depletion. BALB/c mice were fed with normal chow (0.36% K+) or K+-depleted (KD) diet (<0.001% K+) for 8 weeks (n = 5 in each group). Left gastrocnemius muscles were surgically removed from each animal. Histopathological examination showed mild-degree infiltration of polymornuclear and mononuclear cells at the interstitium of the KD muscles. Extracted proteins were resolved with two-dimensional electrophoresis (2-DE), and visualized with Coomassie Brilliant Blue R-250 stain. Quantitative intensity analysis revealed 16 up-regulated protein spots in the KD muscles, as compared to the controls. These differentially expressed proteins were subsequently identified by peptide mass fingerprinting and by quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). Most of the altered proteins induced by chronic potassium depletion were muscle enzymes that play significant roles in several various metabolic pathways. Other up-regulated proteins included myosin-binding protein H, alpha-B Crystallin, and translationally controlled tumor protein (TCTP). These findings may lead to a new roadmap for research on hypokalemic myopathy, to better understanding of the pathophysiology of this medical disease, and to biomarker discovery.

Toward a comprehensive quantitative proteome database: protein expression map of lymphoid neoplasms by 2-D DIGE and MS

Using 2-D DIGE, we constructed a quantitative 2-D database including 309 proteins corresponding to 389 protein spots across 42 lymphoid neoplasm cell lines. The proteins separated by 2-D PAGE were identified by MS and assigned to the expression data obtained by 2-D DIGE. The cell lines were categorized into four groups: those from Hodgkin's lymphoma (HL) (4 cell lines), B cell malignancies (19 cell lines), T cell malignancies (16 cell lines), and natural killer (NK) cell malignancies (3 cell lines). We characterized the proteins in the database by classifying them according to their expression level. We found 28 proteins with more than a 2-fold difference between the cell line groups. We also noted the proteins that allowed multidimensional separation to be achieved (1) between HL cells and other cells, (2) between the cells derived from B cells, T cells and NK cells, and (3) between HL cells and anaplastic large cell lymphoma cells. Decision tree classification identified five proteins that could be used to classify the 42 cell lines according to differentiation. These results suggest that the quantitative 2-D database using 2-D DIGE will be a useful resource for studying the mechanisms underlying the differentiation phenotypes of lymphoid neoplasms.

Expression of the human TPT1 gene coding for translationally controlled tumor protein (TCTP) is regulated by CREB transcription factors

Re-evaluation of genomic and cDNA data revealed that the human TPT1 gene coding for the translationally controlled tumor protein (TCTP) consists of at least 4211 base pairs. It is transcribed into two transcripts of about 0.8 and 1.2 kb, which contain the same coding region and 5'-UTR, but differ in the length of 3'-UTRs by the use of alternative polyadenylation signals. 459 bp promoter sequences were analyzed by theoretical evaluation, reporter-gene assays, gelshift and footprinting experiments to search for transcription factor binding sites. The promoter contains two highly conserved CRE sites between -50 and -89 in close vicinity to a TATA-box at -30. Supershift assays identified CREB I and Fra II of the CREB/ATF1/AP1 family as factors interacting with the CRE/AP1 site. A 3-5-fold stimulation of TCTP synthesis by forskolin and phorbolester in T24 cells and promoter-reporter experiments using CRE-deletion constructs suggested a transcriptional control by cAMP signaling via phosphorylation dependent activation of CRE/CREB interaction.

MMI1 (YKL056c, TMA19), the yeast orthologue of the translationally controlled tumor protein (TCTP) has apoptotic functions and interacts with both microtubules and mitochondria

The yeast orthologue of mammalian TCTP is here proposed to be named Mmi1p (microtubule and mitochondria interacting protein). This protein displays about 50% amino acid sequence identity with its most distantly related orthologs in higher organisms and therefore probably belongs to a small class of yeast proteins which have housekeeping but so far incompletely known functions needed for every eukaryotic cell. Previous investigations of the protein in both higher cells and yeast revealed that it is highly expressed during active growth, but transcriptionally down-regulated in several kinds of stress situations including starvation stress. In human cells, TCTP presumably has anti-apoptotic functions as it binds to Bcl-XL in vivo. TCTP of higher cells was also shown to interact with the translational machinery. It has acquired an additional function in the mammalian immune system, as it is identical with the histamine releasing factor. Here, we show that in S. cerevisiae induction of apoptosis by mild oxidative stress, replicative ageing or mutation of cdc48 leads to translocation of Mmi1p from the cytoplasm to the mitochondria. Mmi1p is stably but reversibly attached to the outer surface of the mitochondria and can be removed by digestion with proteinase K. Glutathionylation of Mmi1p, which is also induced by oxidants, is not a prerequisite or signal for translocation as shown by replacing the only cysteine of Mmi1p by serine. Mmi1p probably interacts with yeast microtubules as deletion of the gene confers sensitivity to benomyl. Conversely, the deletion mutant displays resistance to hydrogen peroxide stress and shows a small but significant elongation of the mother cell-specific lifespan. Our results so far indicate that Mmi1p is one of the few proteins establishing a functional link between microtubules and mitochondria which may be needed for correct localization of mitochondria during cell division.

Mcl-1: a highly regulated cell death and survival controller

Mcl-1 is one member of the Bcl-2 family that has a very short protein half-life. Since its identification in 1993, a great number of studies have implicated that Mcl-1 plays an important role in various cell survival pathways. However, not until recently did the molecular mechanism by which Mcl-1 antagonizes apoptosis have begun to be elucidated. Mcl-1 is rapidly degraded in response to cell death signals and is immediately re-induced by survival stimuli. These results indicate that Mcl-1 plays an apical role in many cell death and survival regulatory programs.

A phloem-enriched cDNA library from Ricinus: insights into phloem function

The aim of this study was to identify genes that are expressed in the phloem. Increased knowledge of phloem regulation will contribute to our understanding of its many roles, from transport of solutes to information about interactions with pathogens. A cDNA library constructed from phloem-enriched sap exuding from cut Ricinus communis (L.) hypocotyls was sequenced. To assess contamination from other tissues, two libraries were constructed: one using the first 15 min of exudation and the other from sap collected after 120 min of exudation had elapsed. Of 1012 clones sequenced, 158 unique transcripts were identified. The presence of marker molecules such as profilin, the low occurrence of chloroplast-related mRNAs, and the sieve element localization of constituent mRNA using in situ hybridization were consistent with a phloem origin of the sap. Functional analysis of the cDNAs revealed classifications including ribosomal function, interaction with the environment, transport, DNA/RNA binding, and protein turnover. An analysis of the closest Arabidopsis thaliana (L.) homologue for each clone indicated that genes involved in cell localization, protein synthesis, tissue localization, organ localization, organ differentiation, and cell fate were represented at twice the level occurring in the whole Arabidopsis genome. The transcripts found in this phloem-enriched library are discussed in the context of phloem function and the relationship between the companion cell and sieve element.

Evolution and expression of Translationally Controlled Tumour Protein (TCTP) of fish

Translationally Controlled Tumour Protein (TCTP) is one of the abundant and ubiquitously expressed proteins in metazoans. In order to better understand its functions in non-mammalians, cDNA encoding full-length TCTP has been isolated and characterized from a teleost fish, Labeo rohita (rohu). Encoded by a 1043 nucleotide mRNA, rohu TCTP consists of 171 amino acids and is expressed in all organs, except in brain. Secondary structure of fish TCTP mRNAs shows that they could be potential substrates for RNA specific protein kinase PKR. The three-dimensional structure of rohu TCTP has been determined, as the first metazoan model of this protein. The conservational and phylogenic clustering of plant and animal TCTP sequences is consistent with the eukaryotic classification, and is suggestive of early origin for the TCTP ortholog in eukaryote evolution, as early as 1.0 x 10(9) years ago. Despite significant conservation, meticulous sequence analysis reveals striking differences that suggest possible new functions for TCTP.

Redox proteomics analysis of oxidatively modified proteins in G93A-SOD1 transgenic mice--a model of familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron degenerative disease characterized by the loss of neuronal function in the motor cortex, brain stem, and spinal cord. Familial ALS cases, accounting for 10-15% of all ALS disease, are caused by a gain-of-function mutation in Cu,Zn-superoxide dismutase (SOD1). Two hypotheses have been proposed to explain the toxic gain of function of mutant SOD (mSOD). One is that mSOD can directly promote reactive oxygen species and reactive nitrogen species generation, whereas the other hypothesis suggests that mSODs are prone to aggregation due to instability or association with other proteins. However, the hypotheses of oxidative stress and protein aggregation are not mutually exclusive. G93A-SOD1 transgenic mice show significantly increased protein carbonyl levels in their spinal cord from 2 to 4 months and eventually develop ALS-like motor neuron disease and die within 5-6 months. Here, we used a parallel proteomics approach to investigate the effect of the G93A-SOD1 mutation on protein oxidation in the spinal cord of G93A-SOD1 transgenic mice. Four proteins in the spinal cord of G93A-SOD1 transgenic mice have higher specific carbonyl levels compared to those of non-transgenic mice. These proteins are SOD1, translationally controlled tumor protein (TCTP), ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1), and, possibly, alphaB-crystallin. Because oxidative modification can lead to structural alteration and activity decline, our current study suggests that oxidative modification of UCH-L1, TCTP, SOD1, and possibly alphaB-crystallin may play an important role in the neurodegeneration of ALS.

An N-terminal region of translationally controlled tumor protein is required for its antiapoptotic activity

Bcl-xL plays a critical role in maintaining cell survival. However, the relationship between the potential interaction of Bcl-xL with other cytosolic proteins and the regulation of cell survival remains incompletely defined. We have identified translationally controlled tumor protein (TCTP), a multifunctional protein, as a novel antiapoptotic Bcl-xL-interacting protein. TCTP interacted in vivo and in vitro with Bcl-xL, and their sites have been mapped to an N-terminal region of TCTP and the Bcl-2 homology domain 3 of Bcl-xL. Consistent with a role in maintaining T-cell survival during activation, TCTP was significantly upregulated in murine T cells activated by T-cell antigen receptor (TCR) ligation and CD28 costimulation, which was correlated with the upregulation of Bcl-xL in activated T cells. Moreover, downregulation of TCTP expression by antisense technology in T cells results in the increase of T-cell apoptosis. Furthermore, the N-terminal region of TCTP was required for its ability to inhibit apoptosis. In conclusion, this study has demonstrated that an N-terminal region of a cytosolic protein, TCTP, is required for its binding to Bcl-xL and for its antiapoptotic activity.

The multidomain protooncogenic protein c-Cbl binds to tubulin and stabilizes microtubules

The protooncogenic protein c-Cbl is known to regulate the actin cytoskeleton. In this study, we present results indicating that c-Cbl can also regulate the microtubular network. We have shown that c-Cbl binds to tubulin and microtubules through its tyrosine kinase binding (TKB) domain. However, the character of the interactions described in this report is novel, since the G306E mutation, which disrupts the ability of c-Cbl's TKB to bind to tyrosine-phosphorylated proteins, does not affect the observed interaction between c-Cbl and microtubules. Furthermore, overexpression of c-Cbl in human pulmonary artery endothelial cells and COS-7 cells leads to microtubule stabilization. We demonstrate that this effect of c-Cbl is mediated by TKB, and, like c-Cbl binding to microtubules, is independent of the ability of TKB to bind to tyrosine-phosphorylated proteins. Finally, we have shown that c-Cbl directly polymerizes microtubules in vitro, and that TKB is necessary and sufficient for this effect of c-Cbl. In this last phenomenon, as well as in the previous ones, the effect of TKB is not sensitive to the inactivating G306E mutation. Overall, the results presented in this report suggest a novel function for c-Cbl-microtubule binding and stabilization.

Getting in and out of mitosis with Polo-like kinase-1

Research in different species has shown that Polo-like kinases are essential for successful cell division. In human cells, Polo-like kinase-1 (Plk1) has been implicated in the regulation of different processes, including mitotic entry, spindle formation and cytokinesis. Recently, a range of new downstream targets of Plk1 has been identified, as well as a molecular mechanism that explains recruitment of Plk1 to potential substrate proteins through its polo-box domain. On the basis of these reports, we discuss possible mechanisms by which Polo-like kinases can exert their multiple functions during mitosis. Polo-like kinases also function in DNA damage checkpoints. Plk1 has been shown to be a target of the G2 DNA damage checkpoint, while Cdc5, the Polo-like kinase in Saccharomyces cerevisiae, has long been known to be required for adaptation to persistent DNA damage. Just recently, a similar requirement for Polo-like kinases during checkpoint adaptation was demonstrated in multicellular organisms. Moreover, Plk1 was also shown to be required for checkpoint recovery following checkpoint inactivation, that is, in cells where the damage is completely repaired. Thus, Plk1 appears to play a role at multiple points during a restart of the cell cycle following DNA damage. Based on these novel observations, we discuss possible consequences of using Plk1 as a target in anticancer strategies.

The molecular and biological analysis of ixodid ticks histamine release factors

We previously described a Dermacentor varibialis (DV) cDNA that encodes a ubiquitously expressed and tick saliva-secreted functional histamine release factor (HRF) homolog. In this study gene specific primers based on DVHRF open reading frame nucleotide sequence were utilized to amplify three orthologs, from the wood tick, D. andersoni (DA), the black legged tick, the southern cattle tick, Boophilus microplus (BM) and the lone star tick, Amblyomma americanum (AA). At nucleotide level, sequence comparisons revealed 98 89 and 84% similarity to DVHRF for DAHRF, AAHRF and BMHRF, respectively, while predicted polypeptide comparisons revealed 98, 96 and 91% similarity for DAHRF, AAHRF and BMHRF respectively. Phylogenetically, the tick HRF clade, while distinct (100% bootstrap value), is closely related to other arthropods, but distantly related to vertebrate and protozoan clades. Consistent with sequence similarity analysis, a DVHRF-specific northern blotting probe hybridized a approximately 900 base pair (bp) mRNA band on all RNA blots. Likewise a mouse polyclonal antibody to E. coli-expressed recombinant (r) DVHRF, cross-reacted baculovirus-expressed non-fusion rAAHRF, rDAHRF, and rBMHRF. As revealed by northern blotting analysis of larvae and nymph RNA, DVHRF mRNA is expressed in both immature and mature ticks indicating that its transcription is not developmentally regulated. Unlike rHRF/TCTP proteins of other organisms, the calcium-binding function may not be conserved for tick HRF homologs as revealed by the 45CaCl2+ overlay assay. Apparent global expression of DVHRF and its orthologs make this protein family an ideal target antigen for development of novel tick control strategies targeting multiple tick species.

Proteome changes in ovarian epithelial cells derived from women with BRCA1 mutations and family histories of cancer

Malignant transformation of the ovarian surface epithelium (OSE) accounts for most ovarian carcinoma. Detection of preneoplastic changes in the OSE leading to overt malignancy is important in prevention and management of ovarian cancer. We identified OSE proteins with altered expression derived from women with a family history (FH) of ovarian and/or breast cancer and mutations in the BRCA1 tumor suppressor gene. Proteins from SV-40-transformed FH-OSE cell lines and control OSE lines derived from women without such histories (non-family history) were separated by two-dimensional PAGE. Gels were analyzed, a protein data base was created, and proteins were characterized according to their molecular weight, isoelectric point, and relative abundance. Mass spectrometry was performed on tryptic protein digests, and data bases were searched for known proteins with the same theoretical tryptic peptide masses. Several proteins showed altered expression in the FH-OSE cells. Beta-tubulin and to a lesser extent ubiquitin carboxyl-terminal hydrolase and glyoxalase 1 appeared to be up-regulated. In contrast, proteins suppressed in FH lines include the 27-kDa heat shock protein, translationally controlled tumor protein, and several proteins associated with actin modification such as actin prepeptide, F-actin capping protein alpha subunit, and cofilin. Sequencing of several cofilin gel spots revealed phosphorylation of serine 3, a post-translational modification associated with decreased actin binding and cytoskeletal reorganization. Two-dimensional Western blots probed with cofilin antibody showed multiple protein spots with isoelectric points of 6-9 pH units. Blots of one-dimensional gels showed a significant reduction in cofilin expression in three FH lines when compared with three non-family history lines (p < or = 0.05). Identification of these and other OSE proteins may be useful in detecting changes suggestive of increased risk of developing preneoplastic disease and defining the possible role(s) of the BRCA1 gene in regulation of OSE cell function.

Translationally controlled tumor protein is a target of tumor reversion

By analyzing the gene expression profile between tumor cells and revertant counterparts that have a suppressed malignant phenotype, we previously reported a significant down-regulation of translationally controlled tumor protein (TCTP) in the revertants. In the present study, we derived, by using the H1 parvovirus as a selective agent, revertants from three major solid cancers: colon, lung, and melanoma cell lines. These cells have a strongly suppressed malignant phenotype both in vitro and in vivo. The level of TCTP is decreased in most of the revertants. To verify whether inhibition of TCTP expression induces changes in the malignant phenotype, in the classical, well established model of "flat reversion," v-src-transformed NIH3T3 cells were transfected with antisense TCTP. By inhibiting the expression of TCTP, the number of revertant cells was raised to 30%, instead of the reported rate for spontaneous flat revertants of 10(-6). Because TCTP encodes for a histamine-releasing factor, we tested the hypothesis that inhibitors of the histaminic pathway could be effective against tumor cells. We show that some antihistaminic compounds (hydroxyzine and promethazine) and other pharmacological compounds with a related structure (including thioridazine and sertraline) kill tumor cells and significantly decrease the level of TCTP. All together, these data suggest that, with tumor reversion used as a working model, TCTP was identified as a target and drugs were selected that decrease its expression and kill tumor cells.

Molecular cloning and expression of a mammalian homologue of a translationally controlled tumor protein (TCTP) gene from Penaeus monodon shrimp

White spot syndrome, caused by white spot syndrome virus (WSSV), is a deadly disease of shrimps, causing a catastrophic loss in shrimp industries worldwide. In order to investigate molecular response of shrimp haemocyte to WSSV infection, we performed subtraction hybridization of mRNAs from healthy and WSSV-infected haemocyte. One of the genes that were severely down-regulated in moribund WSSV-infected-haemocyte was translationally controlled tumor protein (TCTP) (or fortilin). Strikingly, while there was a slight difference in the amount of TCTP message between normal and early WSSV-infected shrimps, shrimps that exhibited severe symptoms uniformly had very little TCTP in their haemocyte. Taken together with the fact that TCTP functions as an anti-apoptotic protein in mammals, our data suggest that TCTP in shrimp protects WSSV-infected shrimps from death.

The translationally controlled tumour protein (TCTP)

The translationally controlled tumour protein (TCTP) is a highly conserved protein that is widely expressed in all eukaryotic organisms. Based on its sequence, TCTP was listed as a separate protein family in protein databases but the recent elucidation of the solution structure of the fission yeast orthologue places it close to a family of small chaperone proteins. The molecular functions determined so far, Ca(2+)- and microtubule-binding, have been mapped to an alpha-helical region of the molecule. TCTP expression is highly regulated both at the transcriptional and translational level and by a wide range of extracellular signals. TCTP has been implicated in important cellular processes, such as cell growth, cell cycle progression, malignant transformation and in the protection of cells against various stress conditions and apoptosis. In addition, an extracellular, cytokine-like function has been established for TCTP, and the protein has been implicated in various medically relevant processes.

TSAP6 Facilitates the Secretion of Translationally Controlled Tumor Protein/Histamine-releasing Factor via a Nonclassical Pathway

Translationally controlled tumor protein (TCTP) is cytoplasmic and structurally related to guanine-nucleotide free chaperones. TCTP (also called histamine-releasing factor) has been described previously as a secreted protein that participates in inflammatory responses by promoting the release of histamine. How TCTP is eventually exported out of the cell to promote such activities is unknown. Here we show that TCTP secretion was insensitive to either brefeldin A or monensin, suggesting that it proceeds via an endoplasmic reticulum/Golgi-independent or nonclassical pathway. Moreover, our analyses also suggest that secreted TCTP originates from pre-existing pools. TSAP6, a p53-inducible 5-6 transmembrane protein, was found to interact with TCTP in a yeast two-hybrid hunt. GST pull down assays confirmed their direct interaction, and immunofluorescence analysis revealed their partial co-distribution to vesicular-like structures at the plasma membrane and around the nucleus. Functionally, the overexpression of TSAP6 consistently leads to enhanced secretion of both endogenously and exogenously expressed TCTP. Finally, we found TCTP in preparations of small secreted vesicles called exosomes, which have been suggested as a possible pathway for nonclassical secretion. Overexpression of TSAP6 also increased TCTP levels in exosome preparations. Altogether, these data identify a novel role for TSAP6 in the export of TCTP and indicate that this multipass membrane protein could have a general role in the regulation of vesicular trafficking and secretion.

Translationally controlled tumor protein interacts with the third cytoplasmic domain of Na,K-ATPase alpha subunit and inhibits the pump activity in HeLa cells

Translationally controlled tumor protein (TCTP) is a growth-related protein under transcriptional as well as translational control. We screened a rat skeletal muscle cDNA library using yeast two-hybrid system and found that TCTP interacts with the third large cytoplasmic domain of alpha1 as well as alpha2 isoforms of Na,K-ATPase, believed involved in the regulation of Na,K-ATPase activity. Interaction between TCTP and Na,K-ATPase was confirmed by coimmunoprecipitation in yeast and mammalian cells. We also showed, using (86)Rb(+) uptake assay, that overexpression of TCTP inhibited Na,K-ATPase activity in HeLa cells. Northern and Western blotting studies of HeLa cells transiently transfected with GFP-tagged TCTP showed that overexpression of TCTP did not change mRNA and protein levels of Na,K-ATPase. Recombinant TCTP protein purified from an Escherichia coli expression system inhibited purified HeLa cell plasma membrane Na,K-ATPase in a dose-dependent manner. Using deletion analysis, we also found that the C-terminal 102-172-amino-acid region of rat TCTP that contains the TCTP homology region 2 is essential for its association with, and inhibition of, Na,K-ATPase.

Molecular cloning and characterization of the translationally controlled tumor protein gene in Bombyx mori

Translationally controlled tumor protein (Tctp/p23) is known to be synthesized preferentially in cells during the early growth phase of tumors, but is also expressed in normal cells. To elucidate its molecular basis of the expression and physiological significance, a cDNA encoding for the Bombyx mori Tctp (BmTctp) was deduced by editing the partial cDNA sequences registered in a Bombyx EST database. RT-PCR analyses indicated that the BmTCTP mRNA was transcribed in all larval organs examined and was present constantly during the cell cycle of BmN4 cells. A genomic clone of 4255 nucloetide residues produced by inverse PCR contained the 5'-flanking region, two introns and three exons of the BmTCTP gene. Sequence analysis of the 5'-flanking region indicated that a putative promoter region contains several canonical transcription elements such as GATA box, CCAAT motif, MEF2, E4BP4.01 and AP-1, but lacks a TATA box element. Luciferase reporter assay of the deletion constructs of the 5'-flanking region revealed that the -676 to +66 region enhanced the promoter activity the most markedly. In addition to this, there were at least two enhancer-like elements and several repressor elements.

A Comprehensive Screen for Chicken Proteins that Interact with Proteins Unique to Virulent Strains of Marek's Disease Virus

Genetic resistance to Marek's disease (MD) has been proposed as a method to augment current vaccinal control of MD. Although it is possible to identify QTL and candidate genes that are associated with MD resistance, it is necessary to integrate functional screens with linkage analysis to confirm the identity of true MD resistance genes. To help achieve this objective, a comprehensive 2-hybrid screen was conducted using genes unique to virulent Marek's disease virus (MDV) strains. Potential MDV-host protein interactions were tested by an in vitro binding assay to confirm the initial two-hybrid results. As a result, 7 new MDV-chicken protein interactions were identified and included the chicken proteins MHC class II beta (BLB) and invariant (Ii) chain (CD74), growth-related translationally controlled tumor protein (TPT1), complement component Clq-binding protein (C1QBP), retinoblastoma-binding protein 4 (RBBP4), and alpha-enolase (ENO1). Mapping of the encoding chicken genes suggests that BLB, the gene for MHC class II beta chain, is a positional candidate gene. In addition, the known functions of the chicken proteins suggest mechanisms that MDV might use to evade the chicken immune system and alter host gene regulation. Taken together, our results indicate that integrated genomic methods provide a powerful strategy to gain insights on complex biological processes and yield a manageable number of genes and pathways for further characterization.

PKD2 Interacts and Co-localizes with mDia1 to Mitotic Spindles of Dividing Cells

Mutations in pkd2 result in the type 2 form of autosomal dominant polycystic kidney disease, which accounts for approximately 15% of all cases of the disease. PKD2, the protein product of pkd2, belongs to the transient receptor potential superfamily of cation channels, and it can function as a mechanosensitive channel in the primary cilium of kidney cells, an intracellular Ca(2+) release channel in the endoplasmic reticulum, and/or a nonselective cation channel in the plasma membrane. We have identified mDia1/Drf1 (mammalian Diaphanous or Diaphanous-related formin 1 protein) as a PKD2-interacting protein by yeast two-hybrid screen. mDia1 is a member of the RhoA GTPase-binding formin homology protein family that participates in cytoskeletal organization, cytokinesis, and signal transduction. We show that mDia1 and PKD2 interact in native and in transfected cells, and binding is mediated by the cytoplasmic C terminus of PKD2 binding to the mDia1 N terminus. The interaction is more prevalent in dividing cells in which endogenous PKD2 and mDia1 co-localize to the mitotic spindles. RNA interference experiments reveal that endogenous mDia1 knockdown in HeLa cells results in the loss of PKD2 from mitotic spindles and alters intracellular Ca(2+) release. Our results suggest that mDia1 facilitates the movement of PKD2 to a centralized position during cell division and has a positive effect on intracellular Ca(2+) release during mitosis. This may be important to ensure equal segregation of PKD2 to the daughter cell to maintain a necessary level of channel activity. Alternatively, PKD2 channel activity may be important in the cell division process or in cell fate decisions after division.

Translationally controlled tumor protein (TCTP) in the human prostate and prostate cancer cells: expression, distribution, and calcium binding activity

BACKGROUND

The translationally controlled tumor protein (TCTP) is an abundantly expressed protein found in a wide range of organisms from both the animal and plant kingdom. Initially described as a growth-related protein, knowledge of the biological actions of TCTP has been recently extended to include calcium binding, regulation of apoptosis, and microtubules stabilization. This report describes expression, distribution, and characterization of TCTP in human prostatic tissues and cell lines.

METHODS

Samples were analyzed by Western blot, RT-PCR, immunohistochemistry, and confocal microscopy. Calcium binding activity of the recombinant human prostatic protein was evaluated on a calcium overlay assay. A public SAGE database was analyzed to determine TCTP expression levels in normal and cancer tissues.

RESULTS

TCTP protein and mRNA were detected in all the specimens and cell lines analyzed. The protein was mainly expressed by the secretory luminal epithelial and basal layer cells. A significant amount of protein was present in the prostatic fluids. Subcellular distribution studies in prostate epithelial cells detected the protein in the cytoplasm in interphase and colocalized with tubulin during mitosis. The calcium binding capacity of prostatic TCTP was shown in vitro. Finally, SAGE data indicated TCTP as the calcium binding protein with the highest expression levels among those examined.

CONCLUSIONS

The results of the present study demonstrate, for the first time, the expression of TCTP in the human prostate and in prostate cancer cells, and suggest the involvement of the protein in key-processes such as apoptosis, cellular differentiation, and in the control of sperm functions.

Stimulation of human bronchial epithelial cells by IgE-dependent histamine-releasing factor

An IgE-dependent histamine-releasing factor (HRF p23; also known as translationally controlled tumor protein or p23) stimulates the release of histamine, IL-4, and IL-13 from a subpopulation of highly allergic donor basophils. It has also been shown to act as a chemoattractant for eosinophils. To elucidate novel functions of HRF p23 in airway inflammation, we examined the effects of human recombinant HRF p23 (hrHRF) on bronchial epithelium and found that hrHRF stimulated the secretions of IL-8 and granulocyte/macrophage colony-stimulating factor by both primary cultures of human bronchial epithelial cells and BEAS-2B cells. In response to hrHRF, these cells induced IL-8 mRNA expression within 4 h. H2O2, but not IL-1 beta or tumor necrosis factor-alpha, stimulated secretion of HRF p23 by BEAS-2B cells, suggesting that oxidative stress may trigger the release of HRF p23 from bronchial epithelial cells. Bronchoalveolar lavage (BAL) from healthy volunteers contained only trivial or undetectable amounts of HRF p23. Significantly higher amounts of HRF p23 were recovered from BAL fluid taken from asthmatic patients, and the amounts of HRF p23 were further elevated in patients with idiopathic eosinophilic pneumonia. Our results demonstrate for the first time that HRF p23 can stimulate nonimmune epithelium. HRF p23 derived from bronchial epithelial cells may regulate complex cytokine networks in eosinophil-dependent inflammation of the human airway.

Translationally controlled tumor protein acts as a guanine nucleotide dissociation inhibitor on the translation elongation factor eEF1A

Recently, we demonstrated that the expression levels of the translationally controlled tumor protein (TCTP) were strongly down-regulated at the mRNA and protein levels during tumor reversion/suppression and by the activation of p53 and Siah-1. To better characterize the function of TCTP, a yeast two-hybrid hunt was performed. Subsequent analysis identified the translation elongation factor, eEF1A, and its guanine nucleotide exchange factor, eEF1Bbeta, as TCTP-interacting partners. In vitro and in vivo studies confirmed that TCTP bound specifically eEF1Bbeta and eEF1A. Additionally, MS analysis also identified eEF1A as a TCTP interactor. Because eEF1A is a GTPase, we investigated the role of TCTP on the nucleotide exchange reaction of eEF1A. Our results show that TCTP preferentially stabilized the GDP form of eEF1A, and, furthermore, impaired the GDP exchange reaction promoted by eEF1Bbeta. These data suggest that TCTP has guanine nucleotide dissociation inhibitor activity, and, moreover, implicate TCTP in the elongation step of protein synthesis.

Proteome analysis of vinca alkaloid response and resistance in acute lymphoblastic leukemia reveals novel cytoskeletal alterations

Vinca alkaloids are used widely in the treatment of both childhood and adult cancers. Their cellular target is the beta-tubulin subunit of alpha/beta-tubulin heterodimers, and they act to inhibit cell division by disrupting microtubule dynamics. Despite the effectiveness of these agents, drug resistance is a major clinical problem. To identify the underlying mechanisms behind vinca alkaloid resistance, we have performed high resolution differential proteome analysis. Treatment of drug-sensitive human leukemia cells (CCRF-CEM) with vincristine identified numerous proteins involved in the cellular response to vincristine. In addition, differential protein expression was analyzed in leukemia cell lines selected for resistance to vincristine (CEM/VCR R) and vinblastine (CEM/VLB100). This combined proteomic approach identified 10 proteins altered in both vinca alkaloid response and resistance: beta-tubulin, alpha-tubulin, actin, heat shock protein 90beta, 14-3-3tau, 14-3-3epsilon, L-plastin, lamin B1, heterogeneous nuclear ribonuclear protein-F, and heterogeneous nuclear ribonuclear protein-K. Several of these proteins have not previously been associated with drug resistance and are thus novel targets for elucidation of resistance mechanisms. In addition, seven of these proteins are associated with the tubulin and/or actin cytoskeletons. This study provides novel insights into the interrelationship between the microtubule and microfilament systems in vinca alkaloid resistance.

Changes in the abundance and distribution of conserved centrosomal, cytoskeletal and ciliary proteins during spermiogenesis in Marsilea vestita

Spermiogenesis in the male gametophytes of the water fern Marsilea vestita is a precise and rapid process resulting in the production of ciliated gametes. Development begins from a single cell within the microspore wall that undergoes nine rapid cell division cycles in distinct planes to produce 32 spermatids that are surrounded by 7 sterile cells. Thereafter, the de novo formation of basal bodies occurs in a discrete cytoplasmic particle known as a blepharoplast, with the subsequent formation of a complex ciliary apparatus in elongating spermatids. The rate and extent of development appear to be controlled at a post-transcriptional level, where the sudden translation of specific stored mRNAs (e.g., centrin) results in the formation of particular structures in the cells (e.g., blepharoplasts). We show here that additional centrosomal and cytoskeletal antigens known as SF assemblin, p95 kDa protein, delta tubulin, gamma tubulin, Xgrip109, Aik, CTR453, RanBPM, BX63, RSP6, and alpha tubulin each exhibit specific localization patterns both on immunoblots of gametophyte protein isolates and in fixed cells. BAp90, PP4, and RLC exhibit specific localization patterns in fixed cells. We show that the antigens exhibit complex patterns of abundance during spermiogenesis. In an attempt to identify regulatory agents involved in spermiogenesis, we employed a RNAi-based screen of 41 randomly selected gametophyte cDNAs on developing populations of synchronously growing gametophytes. The gametophytes treated with each of the RNAi probes exhibited arrest at a specific stage of development. A consequence of anomalous development was the block to assembly of the ciliary apparatus, an effect highlighted by altered staining with anti-centrin, anti-beta-tubulin, and anti-RSP6 antibodies. Our results show that complex, integrated processes of translation and protein partitioning apparently underlie the assembly of the ciliary apparatus during spermiogenesis in male gametophytes of M. vestita.

The American dog tick, Dermacentor variabilis, encodes a functional histamine release factor homolog

We have identified a functional Dermacentor variabilis histamine release factor (DVHRF) homolog and shown that it is a secreted tick saliva protein. The 945 base pair (bp) full-length DVHRF cDNA has a 522 bp open reading frame that encodes a 20 kDa (173 amino acid) polypeptide. Sequence analysis showed that the two HRF signature amino acid sequences were conserved in DVHRF, indicating close structural similarity between DVHRF and other characterized HRF homologs. Northern and Western blotting analyses of partially fed and unfed ticks indicates that neither DVHRF transcriptional nor translational regulation were influenced by tick feeding activity. Like its counterparts from the mammalian system, tick DVHRF is expressed in various tissues, as assessed by both Northern and Western blotting analyses. Furthermore, an Escherichia coli-expressed recombinant DVHRF induced histamine secretion from a rat basophilic leukemic cell line in a dose-dependent manner. Extensive experimental evidence has shown that high levels of histamine at tick attachment sites impede the biological success of feeding ticks and, in response, ticks secrete histamine-binding proteins to minimize the adverse effects of histamine. Our results suggest the existence of a tick-derived multifaceted control mechanism for levels of histamine at tick feeding sites.

Transfer of T-DNA and Vir proteins to plant cells by Agrobacterium tumefaciens induces expression of host genes involved in mediating transformation and suppresses host defense gene expression

Agrobacterium tumefaciens is a plant pathogen that incites crown gall tumors by transferring to and expressing a portion of a resident plasmid in plant cells. Currently, little is known about the host response to Agrobacterium infection. Using suppressive subtractive hybridization and DNA macroarrays, we identified numerous plant genes that are differentially expressed during early stages of Agrobacterium-mediated transformation. Expression profiling indicates that Agrobacterium infection induces plant genes necessary for the transformation process while simultaneously repressing host defense response genes, thus indicating successful utilization of existing host cellular machinery for genetic transformation purposes. A comparison of plant responses to different strains of Agrobacterium indicates that transfer of both T-DNA and Vir proteins modulates the expression of host genes during the transformation process.

Genomic organization and expression of mouse Tpt1 gene

The translationally controlled tumor protein (TCTP), also known as histamine-releasing factor (HRF), is encoded by a gene (Tpt1) that is highly conserved throughout phylogeny. TCTP is implicated in cell growth, acute allergic response, and apoptosis. In the present study, seven putative Tpt1 genes with different chromosomal localizations were identified in the mouse genome. In six of them, analysis of the 5' and 3' untranslated regions revealed the presence of flanking direct repeats and residual poly(A) tails typical of pseudogenes. Only three of the seven genes can produce a protein of the expected molecular weight. We isolated the genomic DNA of these three genes to analyze their sequence, genomic organization, and in vitro promoter activity. We found that mouse Tpt1 is localized on chromosome 14 with a canonical intron-exon organization, a functional promoter, and only one transcript that is ubiquitously expressed in all tissues.

Adenoviral gene transfer of fortilin attenuates neointima formation through suppression of vascular smooth muscle cell proliferation and migration

BACKGROUND

Fortilin, a recently characterized nuclear antiapoptotic factor structurally distinct from inhibitor of apoptosis proteins (IAPs) and Bcl-2 family member proteins, has been suggested to be involved in cell survival and regulation of apoptosis within the cardiovascular system. In this continued investigation, we characterized the influence of adenovirus-mediated fortilin (Ad-fortilin) gene delivery on vascular remodeling after experimental angioplasty.

METHODS AND RESULTS

Vessel wall expression of Ad-fortilin or adenoviral luciferase (Ad-luc) was demonstrated 72 hours and 14 days after rat carotid artery (CA) balloon angioplasty. Morphometric analyses 14 days after injury revealed significantly diminished neointima development in the Ad-fortilin-treated CAs compared with Ad-luc or PBS controls, with no changes in medial wall morphometry observed between the 3 groups. The Ad-fortilin-treated CAs demonstrated a 50% reduction in medial wall proliferating cell nuclear antigen (PCNA) labeling after 72 hours, with significantly reduced neointimal and medial wall PCNA labeling and cell counts after 14 days. Terminal dUTP nick-end labeling results and morphological changes characteristic of programmed cell death suggest a trend toward reduced apoptosis in the fortilin-transfected balloon-injured vessels compared with Ad-luc injured controls. Temporal analysis of human aorta smooth muscle cell (SMC) proliferation demonstrated a marked time-dependent inhibition in Ad-fortilin treated SMCs without the influence of elevated apoptosis. Thymidine incorporation was significantly inhibited in the Ad-fortilin-treated cells compared with Ad-luc controls. Ad-fortilin transfected SMCs also demonstrated significantly decreased migration compared with Ad-luc controls.

CONCLUSIONS

These cumulative results suggest that the novel antiapoptotic protein fortilin may play important redundant pathophysiological roles in modulating the vascular response to experimental angioplasty through suppression of SMC proliferation and migration concomitant with reduction of vessel wall apoptosis.

Plk phosphorylation regulates the microtubule-stabilizing protein TCTP

The mitotic polo-like kinases have been implicated in the formation and function of bipolar spindles on the basis of their respective localizations and mutant phenotypes. To date, this putative regulation has been limited to a kinesin-like motor protein, a centrosomal structural protein, and two microtubule-associated proteins (MAPs). In this study, another spindle-regulating protein, the mammalian non-MAP microtubule-binding and -stabilizing protein, the translationally controlled tumor protein (TCTP), was identified as a putative Plk-interacting clone by a two-hybrid screen. Plk phosphorylates TCTP on two serine residues in vitro and cofractionates with the majority of kinase activity toward TCTP in mitotic cell lysates. In addition, these sites were demonstrated to be phosphorylated in vivo. Overexpression of a Plk phosphorylation site-deficient mutant of TCTP induced a dramatic increase in the number of multinucleate cells, rounded cells with condensed ball-like nuclei, and cells undergoing cell death, similar to both the reported anti-Plk antibody microinjection and the low-concentration taxol treatment phenotypes. These results suggest that phosphorylation decreases the microtubule-stabilizing activity of TCTP and promotes the increase in microtubule dynamics that occurs after metaphase.

Cloning and characterization of a calcium-binding, histamine-releasing protein from Schistosoma mansoni

A homologue of the mammalian translationally controlled tumor protein (TCTP) was cloned from the human parasite Schistosoma mansoni (SmTCTP). Sequence analysis showed that SmTCTP differed from other reported TCTPs in having only one signature sequence. Subsequently, SmTCTP was cloned in a T7 expression system and expressed as a histidine-tagged fusion protein. Recombinant SmTCTP (rSmTCTP) has a molecular mass of approximately 23 kDa with the histidine tag. Further analysis showed that SmTCTP transcripts and protein are expressed in all life cycle stages of the parasite within the vertebrate hosts. Interestingly, antibodies to SmTCTP were present in the sera of mice 9 weeks after infection with S. mansoni. Characterization studies showed that rSmTCTP is a calcium-binding protein that can cause histamine release from basophil/mast cells and induce eosinophil infiltration. These findings suggest that SmTCTP may have an important role in the development of allergic inflammatory responses associated with schistosomiasis and may be a target for new drug development.

Molecular characterization of a calcium binding translationally controlled tumor protein homologue from the filarial parasites Brugia malayi and Wuchereria bancrofti

We have cloned homologues of the mammalian translationally controlled tumor protein (TCTP) from the human filarial parasites Wuchereria bancrofti and Brugia malayi. TCTP genes from B. malayi and W. bancrofti were expressed in a T7 promoter vector as histidine tagged fusion proteins. Both the recombinant B. malayi TCTP (rBm-TCTP) and recombinant W. bancrofti TCTP (rWb-TCTP) have a molecular mass of approximately 28 kDa with the histidine tag. Sequence analyses showed that there is a 98% similarity between the two filarial TCTPs at amino acid levels and are immunologically cross-reactive. Analysis of soluble proteins from various lifecycle stages of B. malayi suggested that the expression of Bm-TCTP might be differentially regulated and occurs in multimeric form. Recombinant TCTP were found to form multimers in solution under non-reducing conditions. The tendency for filarial TCTPs to become multimers was predicted by the presence of the Lupas coiled coil structure in their sequence. Despite the absence of a signal sequence, Bm-TCTP is present abundantly in the excretory/secretions (ES) of microfilariae. Characterization studies showed that both Bm- and Wb-TCTPs are calcium-binding proteins and have histamine-releasing function in vitro. When injected intraperitoneally both the filarial TCTPs induced inflammatory infiltration of eosinophils into the peritoneal cavity of mice suggesting that the filarial TCTPs may have a role in the allergic inflammatory responses associated with filarial infections.

2',3'-Cyclic nucleotide 3'-phosphodiesterase: a membrane-bound, microtubule-associated protein and membrane anchor for tubulin

2',3'-Cyclic nucleotide-3'-phosphodiesterase (CNP) is firmly associated with tubulin from brain tissue and FRTL-5 thyroid cells as demonstrated by copolymerization with microtubules through several warm/cold cycles, the presence of CNP activity in purified tubulin preparations, and identical behavior during various extraction procedures. CNP acts as a microtubule-associated protein in promoting microtubule assembly at low mole ratios. This activity resides in the C terminus of the enzyme, which, by itself, promotes microtubule assembly at higher mole ratios. Phosphorylation of CNP interferes with its assembly-promoting activity, as does deletion of the C terminus, which leads to abnormal microtubule distribution in the cell. Submembranous colocalization of the proteins and CNP-dependent microtubule organization suggest that CNP is a membrane-bound microtubule-associated protein that can link tubulin to membranes and may regulate cytoplasmic microtubule distribution.