The translationally controlled tumour protein (TCTP)

Immunological cross-reactivity analysis on recombinant histamine-releasing factors from Schistosoma japonicum, Clonorchis sinensis, and Wistar rat

Studies have demonstrated a declined incidence of allergic disorders in the population with helminthic infection. Though several hypotheses have been proposed to explain how helminthic infection protected people against allergies, the underlying mechanisms remain poorly understood. A human histamine-releasing factor (HRF) has been proved to be closely related to the development of allergic disorders and the homologues are ubiquitously expressed in all eukaryotic organisms including parasites. To study the role of this HRF in the relationship between parasitic infection and allergic diseases with experimental model of rats, the cDNA of the homologues of the human HRF from Wistar rat, Schistosoma japonicum, and Clonorchis sinensis containing a coding region of 519, 510, and 510 bp, respectively, were cloned. In addition, the cross-reactivity between recombinant rat HRF (rRHRF) and recombinant S. japonicum HRF (rSjHRF) as well as that between rRHRF and recombinant C. sinensis HRF (rCsHRF) was identified with ELISA and Western blotting. Based on their detected cross-reactivities, a hypothesis was put forward that the anti-parasitic HRFs antibodies could inhibit the effects of host HRF and those of parasitic HRFs and thus decreased the host sensitivities to allergens.

Translationally controlled tumor protein from Madurella mycetomatis, a marker for tumorous mycetoma progression

About 40 years ago Abs against the fungus Madurella mycetomatis were first demonstrated to be present in eumycetoma patients, a disease characterized by tumorous swellings. To date nothing is known about the individual immunoreactive Ags present in this fungus. In the present study, we identify its first immunogenic Ag, a protein homologous to the translationally controlled tumor protein (TCTP), a well-conserved histamine release factor in a range of eukaryotes. The gene for this Ag was demonstrated to be present in two variants in M. mycetomatis, with 13% aa difference between the two proteins encoded. In vitro, TCTP was secreted into the culture medium. In vivo, it was found to be expressed on hyphae present in developing stages of the eumycetoma-characteristic black grain. Significant IgG and IgM immune responses, against the whole protein and selected M. mycetomatis-specific peptides, were determined. The Ab levels correlated with lesion size and disease duration. Overall, the patients with the largest lesions had the highest Ab level, which lowered with decreasing size of the lesion. After 6-15 years of disease duration the Ab levels were the highest. TCTP is the first well-characterized immunogenic Ag, simultaneously the first monomolecular vaccine candidate, identified for the fungus M. mycetomatis.

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.

Identification of differentiating neural progenitor cell markers using shotgun isobaric tagging mass spectrometry

The use of neural precursor cells (NPCs) represents a promising repair strategy for many neurological disorders. This requires an understanding of the molecular events and biological features that regulate the self-renewal of NPCs and their differentiation into neurons, astrocytes, and oligodendendrocytes. In this study, we have characterized the proteomic changes that occur upon differentiation of these cells using the novel iTRAQ labeling chemistry for quantitative mass spectrometry. In total, 55 distinct proteins underwent expression changes during NPC differentiation. This included 14 proteins that were identified by our previous two-dimensional difference gel electrophoresis (2D-DIGE) analysis of differentiating mouse neurospheres. The importance of the iTRAQ approach was demonstrated by the identification of additional proteins that were not resolved by the 2D-DIGE technology. The proteins identified by the iTRAQ approach included growth factors, signaling molecules, proliferating cell-specific proteins, heat shock proteins, and other proteins involved in the regulation of metabolism and the transcriptional and translational machinery. Further characterization of the identified proteins should provide greater insight into the mechanisms involved in regulation of neurogenesis in the adult central nervous system and potentially that of other proliferating cell types, including peripheral stem cells or cancer cells.

Proteomic analysis of tumor establishment and growth in the B16-F10 mouse melanoma model

The B16-F10 mouse model of melanoma is a widely used model to study many aspects of cancer biology and therapeutics in a solid tumor. Melanomas aggressively progress within a dynamic microenvironment containing in addition to tumor cells, stroma cells and components such as fibroblasts, immune cells, vascular cells, extracellular matrix (ECM) and extracellular molecules. The goal of this study was to elucidate the processes of tumor progression by identifying differentially expressed proteins in the tumor mass during specific stages of tumor growth. A comparative proteome analysis was performed on B16-F10 derived tumors in C57BL/6 mice at days 3, 5, 7, and 10. Statistical approaches were used to determine quantitative differential protein expression at each tumor time stage. Hierarchical clustering of 44 protein spots (p < 0.01) revealed a progressive change in the tumor mass when all 4 time stages were classified together, but there was a clear switch in expression of these proteins between the day 5 and the day 7 tumors. A trend analysis showed 53 protein spots (p < 0.001) following 6 predominant kinetic paths of expression as the tumor progressed. The protein spots were then identified using MALDI-TOF mass spectrometry. Proteins involved in glycolysis, inflammation, wounding, superoxide metabolism, and chemotaxis increased during tumorigenesis. From day 3 to day 7 VEGF and active cathepsin D were induced 7-fold and 4-fold, respectively. Proteins involved in electron transport, protein folding, blood coagulation, and transport decreased during tumorigenesis. This work illustrates changes in the biology of the B16-F10 tumor mass during tumor progression.

Serological identification and bioinformatics analysis of immunogenic antigens in multiple myeloma

Identifying appropriate tumor antigens is critical to the development of successful specific cancer immunotherapy. Serological analysis of tumor antigens by a recombinant cDNA expression library (SEREX) allows the systematic cloning of tumor antigens recognized by the spontaneous autoantibody repertoire of cancer patients. We applied SEREX to the cDNA expression library of cell line HMy2, which led to the isolation of six known characterized genes and 12 novel genes. Known genes, including ring finger protein 167, KLF10, TPT1, p02 protein, cDNA FLJ46859 fis, and DNMT1, were related to the development of different tumors. Bioinformatics was performed to predict 12 novel MMSA (multiple myeloma special antigen) genes. The prediction of tumor antigens provides potential targets for the immunotherapy of patients with multiple myeloma (MM) and help in the understanding of carcinogenesis. Crude lysate ELISA methodology indicated that the optical density value of MMSA-3 and MMSA-7 were significantly higher in MM patients than in healthy donors. Furthermore, SYBR Green real-time PCR showed that MMSA-1 presented with a high number of copy messages in MM. In summary, the antigens identified in this study may be potential candidates for diagnosis and targets for immunotherapy in MM.

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.

Inhibition of Na,K-ATPase-suppressive activity of translationally controlled tumor protein by sorting nexin 6

Translationally controlled tumor protein (TCTP) has both extra- and intracellular functions. Our group recently reported that TCTP interacts with Na,K-ATPase and suppresses its activity. Our studies led to the identification of sorting nexin 6 (SNX6) which binds with TCTP as a potential negative regulator of TCTP. SNX6 does not interact directly with any cytoplasmic domains of Na,K-ATPase. However, when overexpressed, it restores the Na,K-ATPase activity suppressed by TCTP. This was confirmed by measurements of purified plasma membrane Na,K-ATPase activity after incubation with recombinant TCTP and SNX6. SNX6 alone has no effect on Na,K-ATPase activity, but activates Na,K-ATPase via inhibition of TCTP. Inhibition of endogenous TCTP by the overexpression of SNX6 or knockdown of TCTP expression by siTCTP increased Na,K-ATPase activity above the basal level. The interaction between SNX6 and TCTP thus appears to regulate Na,K-ATPase activity.

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.

Proteomic analysis of p38α mitogen-activated protein kinase-regulated changes in membrane fractions of RAS-transformed fibroblasts

Oncogenic Ras signaling has been long known to play an important role in tumorigenesis and human cancer. In this report, we have used the sensitive 2-D-DIGE coupled to MS for the identification of proteins differentially expressed at the cell membrane level between oncogenic H-RasV12-transformed wild-type and p38alpha-deficient mouse embryo fibroblasts (MEFs). Following trifluoroethanol solubilization, 76 proteins were found to be differentially regulated. After PMF, 63 spots containing 42 different proteins were unequivocally identified by MALDI-TOF MS coupled with database interrogation. As expected, many of them were membrane proteins. Six proteins were selected for further validation studies based on their potential functional link with malignant transformation and signal transduction. These were prohibitin (PHB), protein disulfide isomerase 3 (PDIA3), focal adhesion kinase 2 (FAK2), c-GMP dependent protein kinase 2 (KGP2), NADH-ubiquinone oxidoreductase 30 kDa subunit (NUGM) and translationally controlled tumor protein (TCTP). All these proteins were up-regulated in the membranes of H-RasV12-transformed p38alpha-/-cells, except for prohibitin, which was down-regulated. An excellent correlation was found between DIGE results and Western blot studies, indicating the reliability of the 2-D-DIGE analysis. The available evidence about the putative function of the identified proteins supports the emerging role of p38alpha as a negative regulator of tumorigenesis. Further studies are in progress to elucidate the implications of these findings in the regulation of H-Ras-induced transformation by p38alpha signaling.

Proteomic analysis of neural differentiation of mouse embryonic stem cells

Mouse embryonic stem cells (mESCs) can differentiate into different types of cells, and serve as a good model system to study human embryonic stem cells (hESCs). We showed that mESCs differentiated into two types of neurons with different time courses. To determine the global protein expression changes after neural differentiation, we employed a proteomic strategy to analyze the differences between the proteomes of ES cells (E14) and neurons. Using 2-DE plus LC/MS/MS, we have generated proteome reference maps of E14 cells and derived dopaminergic neurons. Around 23 proteins with an increase or decrease in expression or phosphorylation after differentiation have been identified. We confirmed the downregulation of translationally controlled tumor protein (TCTP) and upregulation of alpha-tubulin by Western blotting. We also showed that TCTP was further downregulated in derived motor neurons than in dopaminergic neurons, and its expression level was independent of extracellular Ca(2+) concentration during neural differentiation. Potential roles of TCTP in modulating neural differentiation through binding to Ca(2+), tubulin and Na,K-ATPase, as well as the functional significance of regulation of other proteins such as actin-related protein 3 (Arp3) and Ran GTPase are discussed. This study demonstrates that proteomic tools are valuable in studying stem cell differentiation and elucidating the underlying molecular mechanisms.

Comprehensive analysis of the renal transcriptional response to acute uranyl nitrate exposure

Background

Chemical and radiological toxicities related to uranium acute exposure have been widely studied in nuclear fuel workers and military personnel. It is well known that uranyl nitrate induces acute renal failure (ARF). However, the mechanisms of this metal-induced injury are not well defined at the molecular level.

Results

Renal function and histology were assessed in mice receiving uranyl nitrate (UN(+)) and controls (UN(-)). To identify the genomic response to uranium exposure, serial analysis gene expression (SAGE) of the kidney was performed in both groups. Over 43,000 mRNA SAGE tags were sequenced. A selection of the differentially expressed transcripts was confirmed by real-time quantitative PCR and Western blotting. UN(+) animals developed renal failure and displayed the characteristic histological lesions of UN nephropathy. Of the >14,500 unique tags identified in both libraries, 224 had a modified expression level; they are known to participate in inflammation, ion transport, signal transduction, oxidative stress, apoptosis, metabolism, and catabolism. Several genes that were identified had not previously been evaluated within the context of toxic ARF such as translationally controlled tumor protein, insulin like growth factor binding protein 7 and ribosomal protein S29, all apoptosis related genes.

Conclusion

We report a comprehensive description of the UN induced modifications in gene expression levels, including the identification of genes previously unrelated to ARF. The study of these genes and the metabolisms they control should improve our understanding of toxic ARF and enlighten on the molecular targets for potential therapeutic interventions.

Homology modeling and molecular docking study of translationally controlled tumor protein and artemisinin

Translationally controlled tumor protein (TCTP), also known as histamine releasing factor (HRF), is found abundantly in different eukaryotic cell types. The sequence homology of TCTP between different species is very high, belonging to the MSS4/DSS4 superfamily of proteins. TCTP is involved in both cell growth and human late allergy reaction, as well as having a calcium binding property; however, its primary biological functions remain to be clearly elucidated. In regard to many possible functions, the TCTP of Plasmodium falciparum (Pf) is known to bind with an antimalarial agent, artemisinin, which is activated by heme. It is assumed that the endoperoxide-bridge of artemisinin is opened up by heme to form a free radical, which then eventually alkylates, probably to the Cys14 of PfTCTP. Study of the docking of artemisinin with heme, and subsequently with PfTCTP, was carried out to verify the above hypothesis on the basis of structural interactions. The three dimensional (3D) structure of PfTCTP was built by homology modeling, using the NMR structure of the TCTP of Schizosaccharomyces pombe as a template. The quality of the model was examined based on its secondary structure and biological function, as well as with the use of structure evaluating programs. The interactions between artemisinin, heme and PfTCTP were then studied using the docking program, FlexiDock. The center of the peroxide bond of artemisinin and the Fe of heme were docked within a short distance of 2.6A, implying the strong possibility of an interaction between the two molecules, as proposed. When the activated form of artemisinin was docked on the PfTCTP, the C4-radical of the drug faced towards the sulfur of Cys14 within a distance of 2.48A, again suggesting the possibility of alkylation having occurred. These results confirm the proposed mechanism of the antimalarial effect of artemisinin, which will provide a reliable method for establishing the mechanism of its biological activity using a molecular modeling study.

Calcium Homeostasis in Human Placenta: Role of Calcium‐Handling Proteins

The human placenta is a transitory organ, representing during pregnancy the unique connection between the mother and her fetus. The syncytiotrophoblast represents the specialized unit in the placenta that is directly involved in fetal nutrition, mainly involving essential nutrients, such as lipids, amino acids, and calcium. This ion is of particular interest since it is actively transported by the placenta throughout pregnancy and is associated with many roles during intrauterine life. At term, the human fetus has accumulated about 25-30 g of calcium. This transfer allows adequate fetal growth and development, since calcium is vital for fetal skeleton mineralization and many cellular functions, such as signal transduction, neurotransmitter release, and cellular growth. Thus, there are many proteins involved in calcium homeostasis in the human placenta.

Analysis of Protein Expression during Oxidative Stress in Breast Epithelial Cells Using a Stable Isotope Labeled Proteome Internal Standard

Normal cells undergo a variety of molecular and physiological changes upon malignant transformation, including their responses to environmental factors that induce oxidative stress. Understanding the molecular pathways regulating these changes would facilitate the development of novel cancer treatments and chemoprevention strategies. Differences in the oxidative stress response were investigated between nonmalignant (S-1) and malignant (T4-2) cell lines (both derived from the HMT-3522 breast epithelial cells) using proteomic approaches. A modification of the stable isotope labeling of amino acids in cell culture (SILAC) approach was employed in which a [(13)C,(15)N]-labeled proteome was prepared from both cells. Relative quantification of the proteome derived from the S-1 cells and the T4-2 cells was then conducted using a [(13)C,(15)N]-labeled proteome as the internal standard. Differentially expressed proteins that changed in a similar manner in both cell lines were mainly stress response proteins, including heat shock proteins, peroxiredoxins, and redox proteins. Proteins that showed significant change in expression level in only one the cell lines included cytoskeleton proteins and proteins implicated in cell cycle and apoptosis regulation. Fortilin was found to be significantly up regulated in the transformed T4-2 cells after H(2)O(2) treatment but not in the parental S-1 cells. However, Ran/TC4 was up regulated by H(2)O(2) in the nonmalignant breast epithelial cells but not in the malignant cells. These results suggest that the malignant T4-2 cells have acquired more resistance to H(2)O(2)-induced apoptosis than the nonmalignant S-1 cells.

The Translationally Controlled Tumor Protein Is a Novel Calcium Binding Protein of the Human Placenta and Regulates Calcium Handling in Trophoblast Cells1

The translationally controlled tumor protein (TPT1, also known as TCTP) is a highly conserved, abundantly expressed protein found in mammals as well as in a wide range of other organisms of both the animal and plant kingdom. Initially considered as a growth-related protein, later studies showed TPT1 is endowed with multiple biological activities, including calcium binding. The present study aimed to evaluate the expression of TPT1 in the human placenta and to examine the functional role of the protein in the calcium binding and homeostasis of trophoblast cells. Samples were analyzed by Western blot, reverse transcription-polymerase chain reaction and immunohistochemistry. The effect of TPT1 knockdown by small interfering RNA (siRNA) on calcium uptake and buffering was assessed in the HTR-8/SVneo cell line. TPT1 protein and mRNA were detected in first-trimester and term placenta. In the tissue, TPT1 was localized in the villous trophoblast. TPT1 expression significantly increased during gestation, with the higher protein and mRNA levels reached at term. Recombinant placental TPT1 bound calcium in vitro, while downregulation of the protein levels by siRNA in HTR-8/SVneo cells was associated with a reduced cellular calcium-uptake activity and buffering capacity. These data demonstrate, for the first time, the expression of TPT1 in the human placenta and support a direct role of the protein in placental calcium transport.

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.

Production and characterization of amplified tumor-derived cRNA libraries to be used as vaccines against metastatic melanomas

Background

Anti-tumor vaccines targeting the entire tumor antigen repertoire represent an attractive immunotherapeutic approach. In the context of a phase I/II clinical trial, we vaccinated metastatic melanoma patients with autologous amplified tumor mRNA. In order to provide the large quantities of mRNA needed for each patient, the Stratagene Creator™ SMART™ cDNA library construction method was modified and applied to produce libraries derived from the tumors of 15 patients. The quality of those mRNA library vaccines was evaluated through sequencing and microarray analysis.

Results

Random analysis of bacterial clones of the library showed a rate of 95% of recombinant plasmids among which a minimum of 51% of the clones contained a full-Open Reading Frame. In addition, despite a biased amplification toward small abundant transcripts compared to large rare fragments, we could document a relatively conserved gene expression profile between the total RNA of the tumor of origin and the corresponding in vitro transcribed complementary RNA (cRNA). Finally, listing the 30 most abundant transcripts of patient MEL02's library, a large number of tumor associated antigens (TAAs) either patient specific or shared by several melanomas were found.

Conclusion

Our results show that unlimited amounts of cRNA representing tumor's transcriptome could be obtained and that this cRNA was a reliable source of a large variety of tumor antigens.

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.

Proteome alterations in gamma-irradiated human T-lymphocyte leukemia cells

Analyses of the protein expression profiles of irradiated cells may be beneficial for identification of new biomolecules of radiation-induced cell damage. Therefore, in this study we exploited the proteomic approach to identify proteins whose expression is significantly altered in gamma-irradiated human T-lymphocyte leukemia cells. MOLT-4 cells were irradiated with 7.5 Gy and the cell lysates were collected at different times after irradiation (2, 5 and 12 h). The proteins were separated by two-dimensional electrophoresis and quantified using an image evaluation system. Proteins exhibiting significant radiation-induced alterations in abundance were identified by peptide mass fingerprinting. We identified 14 proteins that were either up- or down-regulated. Cellular levels of four of the proteins (Rho GDP dissociation inhibitor 1 and 2, Ran binding protein 1, serine/threonine protein kinase PAK2) were further analyzed by two-dimensional immunoblotting to confirm the data obtained from proteome analysis. All identified proteins were classified according to their cellular function, including their participation in biochemical and signaling pathways. Taken together, our results suggest the feasibility of the proteome method for monitoring of cellular radiation responses.

The transcript composition of egg cells changes significantly following fertilization in wheat (Triticum aestivum L.)

Here, we report the transcript profile of wheat egg cells and proembryos, just after the first cell division. Microdissected female gametophytes of wheat were used to isolate eggs and two-celled proembryos to construct cell type-specific cDNA libraries. In total, 1197 expressed sequence tags (ESTs) were generated. Analysis of these ESTs revealed numerous novel transcripts. In egg cells, 17.6% of the clustered ESTs represented novel transcripts, while 11.4% novel clusters were identified in the two-celled proembryo. Functional classification of sequences with similarity to previously characterized proteins indicates that the unfertilized egg cell has a higher metabolic activity and protein turnover than previously thought. Transcript composition of two-celled proembryos was significantly distinct from egg cells, reflecting DNA replication as well as high transcriptional and translational activity. Several novel transcripts of the egg cell are specific for this cell. In contrast, some fertilization induced novel mRNAs are abundant also in sporophytic tissues indicating a more general role in plant growth and development. The potential functions of genes based on similarity to known genes involved in developmental processes are discussed. Our analysis has identified numerous genes with potential roles in embryo sac function such as signaling, fertilization or induction of embryogenesis.

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.

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 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.