Identification and transcription control of fission yeast genes repressed by an ammonium starvation growth arrest

Targeting TCTP sensitizes tumor to T cell-mediated therapy by reversing immune-refractory phenotypes

Immunotherapy has emerged as a powerful approach to cancer treatment. However, immunotherapeutic resistance limits its clinical application. Therefore, identifying immune-resistant factors, which can be targeted by clinically available drugs and it also can be a companion diagnostic marker, is needed to develop combination strategies. Here, using the transcriptome data of patients, and immune-refractory tumor models, we identify TCTP as an immune-resistance factor that correlates with clinical outcome of anti-PD-L1 therapy and confers immune-refractory phenotypes, decreased T cell trafficking to the tumor and resistance to cytotoxic T lymphocyte-mediated tumor cell killing. Mechanistically, TCTP activates the EGFR-AKT-MCL-1/CXCL10 pathway by phosphorylation-dependent interaction with Na, K ATPase. Furthermore, treatment with dihydroartenimsinin, the most effective agent impending the TCTP-mediated-refractoriness, synergizes with T cell-mediated therapy to control immune-refractory tumors. Thus, our findings suggest a role of TCTP in promoting immune-refractoriness, thereby encouraging a rationale for combination therapies to enhance the efficacy of T cell-mediated therapy.

Translationally controlled tumor protein (TCTP) regulates several cellular processes, including apoptosis, and is overexpressed in several cancer types. Here, the authors report that high levels of TCTP are associated with poor response to anti-PD-L1 and that TCTP targeting increases the efficacy of T cell-mediated anti-tumor therapy.

Identification of novel inhibitors of the translationally controlled tumor protein (TCTP): insights from molecular dynamics

The translationally controlled tumor protein (TCTP) is a highly conserved multifunctional protein, preferentially expressed in mitotically active tissues and is a potential biomarker and a therapeutic target for lung cancers. An understanding of the biology of this molecule and model systems for the screening of drugs is still awaited. In the absence of complete crystal structure, NMR structures as templates were used for homology modeling and MD optimization of both Dictyostelium discoideum and human TCTPs, which was followed by pocket-site prediction, ligand screening and docking. Rescoring of TCTP-ligand complexes was done using MD and MM-PBSA approaches. D. discoideum TCTP was expressed under a constitutive promoter and the endogenous RNA in multicellular structures formed was localized by in situ hybridization. Based on the interactions and binding energy scores, two novel compounds were identified as the best potential inhibitors that could be further used for the development of drug candidates. Inhibition of cell proliferation was observed in the strain overexpressing Dictyostelium TCTP and in situ hybridization results show them to be localized in the prestalk (dying cell population) cells. D. discoideum and human TCTPs share similar dynamic behaviors; overexpression of Dictyostelium TCTP inhibits cell proliferation. D. discoideum could be used as a model system for understanding the biology of this molecule and also for drug screening.

Function of Translationally Controlled Tumor Protein in Organ Growth: Lessons from Drosophila Studies

Regulation of cell growth and proliferation is crucial for development and function of organs in all animals. Genetic defects in growth control can lead to developmental disorders and cancers. Translationally controlled tumor protein (TCTP) is a family of evolutionarily conserved proteins implicated in cancer. Recent studies have revealed multiple roles of TCTP in diverse cellular events, but TCTP functions in vivo are poorly understood in vertebrate systems. We have used Drosophila melanogaster, the fruit fly, as a model organism for genetic dissection of Tctp function. Our studies have shown that Tctp is essential for organ development by regulating growth signaling. Furthermore, it is required for genome stability by promoting DNA repair and chromatin remodeling in the nucleus. Thus, Tctp acts as a multifaceted cytosolic and nuclear factor for regulating organ growth and genome stability. In this chapter, we describe an overview of our findings on Tctp functions in Drosophila and discuss their implications in cancer.

A novel Meloidogyne enterolobii effector MeTCTP promotes parasitism by suppressing programmed cell death in host plants

Meloidogyne enterolobii is one of the most important plant-parasitic nematodes that can overcome the Mi-1 resistance gene and damage many economically important crops. Translationally controlled tumour protein (TCTP) is a multifunctional protein that exists in various eukaryotes and plays an important role in parasitism. In this study, a novel M. enterolobii TCTP effector, named MeTCTP, was identified and functionally characterized. MeTCTP was specifically expressed within the dorsal gland and was up-regulated during M. enterolobii parasitism. Transient expression of MeTCTP in protoplasts from tomato roots showed that MeTCTP was localized in the cytoplasm of the host cells. Transgenic Arabidopsis thaliana plants overexpressing MeTCTP were more susceptible to M. enterolobii infection than wild-type plants in a dose-dependent manner. By contrast, in planta RNA interference (RNAi) targeting MeTCTP suppressed the expression of MeTCTP in infecting nematodes and attenuated their parasitism. Furthermore, MeTCTP could suppress programmed cell death triggered by the pro-apoptotic protein BAX. These results demonstrate that MeTCTP is a novel plant-parasitic nematode effector that promotes parasitism, probably by suppressing programmed cell death in host plants.

The Translational Controlled Tumour Protein TCTP: Biological Functions and Regulation

The Translational Controlled Tumour Protein TCTP (gene symbol TPT1, also called P21, P23, Q23, fortilin or histamine-releasing factor, HRF) is a highly conserved protein present in essentially all eukaryotic organisms and involved in many fundamental cell biological and disease processes. It was first discovered about 35 years ago, and it took an extended period of time for its multiple functions to be revealed, and even today we do not yet fully understand all the details. Having witnessed most of this history, in this chapter, I give a brief overview and review the current knowledge on the structure, biological functions, disease involvements and cellular regulation of this protein.TCTP is able to interact with a large number of other proteins and is therefore involved in many core cell biological processes, predominantly in the response to cellular stresses, such as oxidative stress, heat shock, genotoxic stress, imbalance of ion metabolism as well as other conditions. Mechanistically, TCTP acts as an anti-apoptotic protein, and it is involved in DNA-damage repair and in cellular autophagy. Thus, broadly speaking, TCTP can be considered a cytoprotective protein. In addition, TCTP facilitates cell division through stabilising the mitotic spindle and cell growth through modulating growth signalling pathways and through its interaction with the proteosynthetic machinery of the cell. Due to its activities, both as an anti-apoptotic protein and in promoting cell growth and division, TCTP is also essential in the early development of both animals and plants.Apart from its involvement in various biological processes at the cellular level, TCTP can also act as an extracellular protein and as such has been involved in modulating whole-body defence processes, namely in the mammalian immune system. Extracellular TCTP, typically in its dimerised form, is able to induce the release of cytokines and other signalling molecules from various types of immune cells. There are also several examples, where TCTP was shown to be involved in antiviral/antibacterial defence in lower animals. In plants, the protein appears to have a protective effect against phytotoxic stresses, such as flooding, draught, too high or low temperature, salt stress or exposure to heavy metals. The finding for the latter stress condition is corroborated by earlier reports that TCTP levels are considerably up-regulated upon exposure of earthworms to high levels of heavy metals.Given the involvement of TCTP in many biological processes aimed at maintaining cellular or whole-body homeostasis, it is not surprising that dysregulation of TCTP levels may promote a range of disease processes, foremost cancer. Indeed a large body of evidence now supports a role of TCTP in at least the most predominant types of human cancers. Typically, this can be ascribed to both the anti-apoptotic activity of the protein and to its function in promoting cell growth and division. However, TCTP also appears to be involved in the later stages of cancer progression, such as invasion and metastasis. Hence, high TCTP levels in tumour tissues are often associated with a poor patient outcome. Due to its multiple roles in cancer progression, TCTP has been proposed as a potential target for the development of new anti-cancer strategies in recent pilot studies. Apart from its role in cancer, TCTP dysregulation has been reported to contribute to certain processes in the development of diabetes, as well as in diseases associated with the cardiovascular system.Since cellular TCTP levels are highly regulated, e.g. in response to cell stress or to growth signalling, and because deregulation of this protein contributes to many disease processes, a detailed understanding of regulatory processes that impinge on TCTP levels is required. The last section of this chapter summarises our current knowledge on the mechanisms that may be involved in the regulation of TCTP levels. Essentially, expression of the TPT1 gene is regulated at both the transcriptional and the translational level, the latter being particularly advantageous when a rapid adjustment of cellular TCTP levels is required, for example in cell stress responses. Other regulatory mechanisms, such as protein stability regulation, may also contribute to the regulation of overall TCTP levels.

The first characterization of gene structure and biological function for echinoderm translationally controlled tumor protein (TCTP)

Translationally controlled tumor protein (TCTP) is a multifunctional protein that existed ubiquitously in different eukaryote species and distributed widely in various tissues and cell types. In this study, the gene structure and biological function of TCTP were first characterized in echinoderm. An echinoderm TCTP named StmTCTP was identified from sea cucumber (Stichopus monotuberculatus) by expression sequence tag (EST) analysis and rapid amplification of cDNA ends (RACE) approach. The StmTCTP cDNA is 1219 bp in length, containing a 5'-untranslated region (UTR) of 77 bp, a 3'-UTR of 623 bp and an open reading frame (ORF) of 519 bp that encoding a protein of 172 amino acids with a deduced molecular weight of 19.80 kDa and a predicted isolectric point of 4.66. Two deduced signal signatures termed TCTP1 and TCTP2, a microtubule binding domain, a Ca(2+) binding domain and the conserved residues forming Rab GTPase binding surface were found in the StmTCTP amino acid sequence. For the gene structure, StmTCTP contains four exons separated by three introns. The anti-oxidation and heat shock protein activities of recombinant TCTP protein were also demonstrated in this study. In addition, the expression of StmTCTP was found to be significantly upregulated by polyriboinosinic polyribocytidylic acid [poly (I:C)], lipopolysaccharides (LPS) or inactivated bacteria challenge in in vitro primary culture experiments of coelomocytes, suggested that the sea cucumber TCTP might play critical roles not only in the defense against oxidative and thermal stresses, but also in the innate immune defense against bacterial and viral infections.

Ligand binding reveals a role for heme in translationally-controlled tumor protein dimerization

The translationally-controlled tumor protein (TCTP) is a highly conserved, ubiquitously expressed, abundant protein that is broadly distributed among eukaryotes. Its biological function spans numerous cellular processes ranging from regulation of the cell cycle and microtubule stabilization to cell growth, transformation, and death processes. In this work, we propose a new function for TCTP as a “buffer protein” controlling cellular homeostasis. We demonstrate that binding of hemin to TCTP is mediated by a conserved His-containing motif (His⁷⁶His⁷⁷) followed by dimerization, an event that involves ligand-mediated conformational changes and that is necessary to trigger TCTP's cytokine-like activity. Mutation in both His residues to Ala prevents hemin from binding and abrogates oligomerization, suggesting that the ligand site localizes at the interface of the oligomer. Unlike heme, binding of Ca²⁺ ligand to TCTP does not alter its monomeric state; although, Ca²⁺ is able to destabilize an existing TCTP dimer created by hemin addition. In agreement with TCTP's proposed buffer function, ligand binding occurs at high concentration, allowing the “buffer” condition to be dissociated from TCTP's role as a component of signal transduction mechanisms.

TCTP as therapeutic target in cancers

The translationally controlled tumor protein (TCTP) is a highly conserved protein present in eukaryotic organisms. This protein, located both in the cytoplasmic and the nucleus, is expressed in various tissues and is regulated in response to a wide range of extracellular stimuli. TCTP interacts with itself and other protein including MCL1 and p53. TCTP has been shown to play an important role in physiological events, such as cell proliferation, cell death and immune responses but also in stress response and tumor reversion. Moreover, TCTP expression is associated with malignancy and chemoresistance. In this review, we will evaluate pathways regulated by TCTP and current inhibitory strategy to target TCTP in cancerous diseases.

The C-terminal cysteine of turbot Scophthalmus maximus translationally controlled tumour protein plays a key role in antioxidation and growth-promoting functions

The translationally controlled tumour protein (TCTP) of turbot Scophthalmus maximus (SmTCTP) contains only one cysteine (Cys¹⁷⁰) at the C-terminal end. The biological role of this C-terminal Cys¹⁷⁰ in the antioxidation and growth-promoting functions of SmTCTP was examined by site-directed mutation of C170A (Cys¹⁷⁰ →Ala¹⁷⁰). It was found that C170A mutation not only obviously decreased the antioxidation capacity of the mutant-smtctp-transformed bacteria exposed to 0·22 mM hydrogen peroxide, but also significantly interrupted the normal growth and survival of the mutant-smtctp-transformed bacteria and flounder Paralichthys olivaceus gill (FG) cells, indicating a key role played by Cys¹⁷⁰ in the antioxidation and growth-promoting functions of SmTCTP. This study also suggested that the self-dimerization or dimerization with other interacting proteins is critical to the growth-promoting function of SmTCTP.

TCTP is a critical factor in shrimp immune response to virus infection

The translationally controlled tumor protein (TCTP) is an abundant, ubiquitous, and conserved protein which plays important roles in a number of biological processes. In the present study, the TCTP in shrimp Litopenaeus vannamei was analyzed. The TCTP of L.vannamei, a 168-amino-acid polypeptide, shares a high degree of similarity with TCTPs from other species, having two TCTP protein signatures at the 45–55 aa and 123–145 aa motif. The mRNA and protein levels from different tissues were detected with the highest in muscle and the lowest in heart among all examined tissues. In addition, temporal TCTP expression was significantly up-regulated at 16 h and 48 h following infection with white spot syndrome virus (WSSV). Lastly, silencing of TCTP with dsRNA led to a significant increase of WSSV loads. These results provide new insights into the importance of TCTP as an evolutionarily conserved molecule for shrimp innate immunity against virus infection.

Molecular cloning, expression profiles and characterization of a novel translationally controlled tumor protein in rubber tree (Hevea brasiliensis)

The translationally controlled tumor protein (TCTP) is a multi-functioning protein that carries out vital roles in various life processes. In this study, a new TCTP gene, designated as HbTCTP1, was isolated in Hevea brasiliensis. The full-length complementary DNA (cDNA) of HbTCTP1 contained a maximum open reading frame (ORF) of 507base pair (bp) encoding 168 amino acids. The sequence comparison showed that the deduced HbTCTP1 indicated high identities to plant TCTP proteins, and clustered in the dicot cluster of plant TCTPs. Although HbTCTP1 and human TCTP proteins did not parallel in overall sequence similarity, they indicated highly similar 3D structures with a nearly identical spatial organization of α-helices, β-sheets, and coil regions. Real time reverse-transcription PCR (RT-PCR) analyses showed that HbTCTP1 was expressed throughout different tissues and developmental stages of leaves. Besides being related to tapping panel dryness (TPD), the HbTCTP1 transcripts were regulated by various treatments, including drought, low temperature, high salt, ethrel (ET), wounding, H2O2, and methyl jasmonate (Me-JA) treatments. The recombinant HbTCTP1 fusion protein was shown to protect supercoiled plasmid DNA from damages induced by metal-catalyzed generation of reactive oxygen species. The (45)Ca(2+)-overlay assay showed that HbTCTP1 was a calcium-binding protein. Our results are greatly helpful in understanding the molecular characterization and expression profiles of HbTCTP1, and lay the foundation for further analyzing the function of HbTCTP1 in rubber tree.

Grouper translationally controlled tumor protein prevents cell death and inhibits the replication of Singapore grouper iridovirus (SGIV)

Translationally controlled tumor protein (TCTP) is an important molecule involved in multiple biological processes, such as cell growth, cell cycle progression, malignant transformation, and enhancement of the anti-apoptotic activity. In this study, the TCTP from orange-spotted grouper Epinephelus coioides (Ec-TCTP) was cloned and characterized. The full-length cDNA of Ec-TCTP was comprised of 1057 bp with a 510 bp open reading frame that encodes a putative protein of 170 amino acids. Recombinant Ec-TCTP (rEc-TCTP) was expressed in Escherichia BL21 (DE3) and purified for mouse anti-Ec-TCTP serum preparation. The rEc-TCTP fusion protein was demonstrated to possess antioxidant activity, which conferred resistance to H(2)O(2) damage. Quantitative real-time PCR analysis revealed that Ec-TCTP mRNA is predominately expressed in the liver, and the expression was up-regulated in the liver of grouper after viral challenge with Singapore grouper iridovirus (SGIV). Intracellular localization revealed that Ec-TCTP expression was distributed predominantly in the cytoplasm. Although human TCTP has a role in apoptosis regulation, it is not known if grouper TCTP has any role in apoptosis regulation. Strikingly, grouper TCTP, when overexpressed in fathead minnow (FHM) cells, protected them from cell death induced by cycloheximide (CHX). In addition, overexpressed Ec-TCTP in grouper spleen (GS) cells inhibited the replication of SGIV. These results suggest that Ec-TCTP may play a critical role in their response to SGIV infection, through regulation of a cell death pathway that is common to fish and humans.

Overexpression of Arabidopsis translationally controlled tumor protein gene AtTCTP enhances drought tolerance with rapid ABA-induced stomatal closure

Translationally controlled tumor protein (TCTP), also termed P23 in human, belongs to a family of calcium- and tubulin-binding proteins, and it is generally regarded as a growth-regulating protein. Recently, Arabidopsis TCTP (AtTCTP) has been reported to function as an important growth regulator in plants. On the other hand, plant TCTP has been suggested to be involved in abiotic stress signaling such as aluminum, salt, and water deficit by a number of microarray or proteomic analyses. In this study, the biological functions of AtTCTP were investigated by using transgenic Arabidopsis plants overexpressing AtTCTP. Interestingly, AtTCTP overexpression enhanced drought tolerance in plants. The expression analysis showed that AtTCTP was expressed in guard cells as well as in actively growing tissues. Physiological studies of the overexpression lines showed increased ABA- and calcium-induced stomatal closure ratios and faster stomatal closing responses to ABA. Furthermore, in vitro protein-protein interaction analysis confirmed the interaction between AtTCTP and microtubules, and microtubule cosedimentation assays revealed that the microtubule binding of AtTCTP increased after calcium treatment. These results demonstrate that the overexpression of AtTCTP confers drought tolerance to plants by rapid ABA-mediated stomatal closure via the interaction with microtubules in which calcium binding enhances the interaction. Collectively, the present results suggest that the plant TCTP has molecular properties similar to animal TCTPs, such as tubulin- and calcium-binding, and that it functions in ABA-mediated stomatal movement, in addition to regulating the growth of plants.

Sumoylation of human translationally controlled tumor protein is important for its nuclear transport

Translationally controlled tumor protein (TCTP) lacks nuclear bipartite localization signal sequence; yet TCTP is present abundantly in the nucleus. At present it is not known how TCTP gets transported to the nucleus. Sequence analyses showed that all TCTPs described to date have putative small ubiquitin-like modifier (SUMO) motifs. Since SUMO modification plays an important role in the nuclear transport of proteins, we evaluated whether SUMO motifs are important for transport of TCTP into the nucleus. We show that TCTP exists in sumoylated form in cytoplasm and nucleus of mammalian cells. Point mutation of lysine residue in the SUMO motif compromised the ability of TCTP to get sumoylated in vitro. When cells were transfected with FLAG-tagged mutated TCTP, nuclear transport of TCTP was inhibited confirming that sumoylation is critical for the nuclear transport of TCTP. Our previous studies demonstrated that TCTP can function as an antioxidant protein in the nucleus. When we mutated TCTP at the SUMO motif the antioxidant function of TCTP was compromised. Results presented in this study thus show that sumoylation plays an important role in the transport of TCTP into the nucleus where they function as antioxidant protein.

Upregulation of TCTP expression in human skin squamous cell carcinoma increases tumor cell viability through anti-apoptotic action of the protein

The translationally controlled tumor protein (TCTP) is an anti-apoptotic protein, which is highly expressed in several human cancer types. However, the role of TCTP in skin cancers, including squamous cell carcinoma (SCC), has not been investigated. In this study, we analyzed the expression of TCTP in cutaneous SCC samples using immunohistochemistry in two epidermoid SCC cell lines, A431 and SCL-1, using western blot analysis. We further investigated the role of TCTP in skin cancinogenesis by silencing the TPT1 gene using small interfering RNA (siRNA) in the SCC cell line A431. Our results demonstrated that TCTP was overexpressed in cutaneous SCC cells, compared to normal skin keratinocytes. In addition, the expression of TCTP in skin SCC significantly increased with the grade of malignancy. Western blot analysis further confirmed that the expression of TCTP in the cell lines, A431 and SCL-1, was significantly higher compared to that in the normal keratinocyte cell line, HaCaT. The expression of TCTP in A431 cells was significantly downregulated by transfection with our specifically designed TCTP siRNA. We found that downregulation of TCTP expression was associated with decreased cell proliferation and increased apoptosis in A431 cells. These results suggest that the TPT1 gene may be a potential therapeutic target in skin SCC through a siRNA approach.

A novel TCTP gene from the crustacean Eriocheir sinensis: possible role involving metallic Cu2+ stress

The translationally controlled tumor protein (TCTP), which was initially described as a growth-related protein, primarily expresses proteins for numerous biological processes in eukaryotes. In the present study, the TCTP gene in the Chinese mitten crab Eriocheir sinensis (Es-TCTP) was identified from tissues of the hepatopancreas, by the construction of a cDNA library and the rapid amplification of cDNA ends. The results showed that the full length of Es-TCTP cDNA comprises 727 nucleotides, with an open reading frame of 507 bp that encodes 168 amino acid residues. The deduced amino acid sequence of Es-TCTP has a 51%-92% similarity to TCTPs of other eukaryotic species. The mRNA transcripts of Es-TCTP were detected by using RT-PCR for all tissues, with the highest level occurring in the hepatopancreas. In addition, temporal expression of the Es-TCTP was measured to analyze the role of Es-TCTP in an acute stress condition after CuSO(4) treatment. The expression of the Es-TCTP transcripts in hepatopancreas had no significant difference at the first 4 h, but increased significantly after 8 h, peaked at 24 h (4.3-fold higher than the control), and was still high after 72 h. Our results indicate that Es-TCTP is an acute-phase protein that is involved in Cu(2+) stress, with a possible anti-stress function in invertebrates.

Shrimp Pm-fortilin inhibits the expression of early and late genes of white spot syndrome virus (WSSV) in an insect cell model

Fortilin plays an important role in anti-apoptotic mechanisms and cell proliferation in many eukaryotic organisms. This work confirmed previous reports that Sf9 can support the replication of white spot syndrome virus (WSSV) genomic material by using immunohistochemistry with a specific antibody to detect the immediate early gene 1 (ie1) and by amplification of WSSV DNA and mRNA products. Using this insect-cell model system, we show that overexpression of Pm-fortilin in Sf9 cells inhibited the expression of WSSV early genes and late genes (WSSV-DNA polymerase, VP15 and VP28) but not an immediate early gene ie1. This is the first time that an insect cell line has been used to demonstrate interaction between a shrimp gene and genes of a shrimp virus.

Fission yeast TORC1 regulates phosphorylation of ribosomal S6 proteins in response to nutrients and its activity is inhibited by rapamycin

Cellular activities are regulated by environmental stimuli through protein phosphorylation. Target of rapamycin (TOR), a serine/threonine kinase, plays pivotal roles in cell proliferation and cell growth in response to nutrient status. In Schizosaccharomyces pombe, TORC1, which contains Tor2, plays crucial roles in nutrient response. Here we find a nitrogen-regulated phosphoprotein, p27, in S. pombe using the phospho-Akt substrate antibody. Response of p27 phosphorylation to nitrogen availability is mediated by TORC1 and the TSC-Rhb1 signaling, but not by TORC2 or other nutrient stress-related pathways. Database and biochemical analyses indicate that p27 is identical to ribosomal protein S6 (Rps6). Ser235 and Ser236 in Rps6 are necessary for Rps6 phosphorylation by TORC1. These Rps6 phosphorylations are dispensable for cell viability. Rps6 phosphorylation by TORC1 also responds to availability of glucose and is inhibited by osmotic and oxidative stresses. Rapamycin inhibits the ability of TORC1 to phosphorylate Rps6, owing to interaction of the rapamycin-FKBP12 complex with the FRB domain in Tor2. Rapamycin also leads to a decrease in cell size in a TORC1-dependent manner. Our findings demonstrate that the nutrient-responsive and rapamycin-sensitive TORC1-S6 signaling exists in S. pombe, and that this pathway plays a role in cell size control.

Heat-shock responsive genes identified and validated in Atlantic cod (Gadus morhua) liver, head kidney and skeletal muscle using genomic techniques

BACKGROUND

Daily and seasonal changes in temperature are challenges that fish within aquaculture settings cannot completely avoid, and are known to elicit complex organismal and cellular stress responses. We conducted a large-scale gene discovery and transcript expression study in order to better understand the genes that are potentially involved in the physiological and cellular aspects of stress caused by heat-shock. We used suppression subtractive hybridization (SSH) cDNA library construction and characterization to identify transcripts that were dysregulated by heat-shock in liver, skeletal muscle and head kidney of Atlantic cod. These tissues were selected due to their roles in metabolic regulation, locomotion and growth, and immune function, respectively. Fish were exposed for 3 hours to an 8 degrees C elevation in temperature, and then allowed to recover for 24 hours at the original temperature (i.e. 10 degrees C). Tissue samples obtained before heat-shock (BHS), at the cessation of heat-shock (CS), and 3, 12, and 24 hours after the cessation of heat-shock (ACS), were used for reciprocal SSH library construction and quantitative reverse transcription - polymerase chain reaction (QPCR) analysis of gene expression using samples from a group that was transferred but not heat-shocked (CT) as controls.

RESULTS

We sequenced and characterized 4394 ESTs (1524 from liver, 1451 from head kidney and 1419 from skeletal muscle) from three "forward subtracted" libraries (enriched for genes up-regulated by heat-shock) and 1586 from the liver "reverse subtracted" library (enriched for genes down-regulated by heat-shock), for a total of 5980 ESTs. Several cDNAs encoding putative chaperones belonging to the heat-shock protein (HSP) family were found in these libraries, and "protein folding" was among the gene ontology (GO) terms with the highest proportion in the libraries. QPCR analysis of HSP90alpha and HSP70-1 (synonym: HSPA1A) mRNA expression showed significant up-regulation in all three tissues studied. These transcripts were more than 100-fold up-regulated in liver following heat-shock. We also identified HSP47, GRP78 and GRP94-like transcripts, which were significantly up-regulated in all 3 tissues studied. Toll-like receptor 22 (TLR22) transcript, found in the liver reverse SSH library, was shown by QPCR to be significantly down-regulated in the head kidney after heat-shock.

CONCLUSION

Chaperones are an important part of the cellular response to stress, and genes identified in this work may play important roles in resistance to thermal-stress. Moreover, the transcript for one key immune response gene (TLR22) was down-regulated by heat-shock, and this down-regulation may be a component of heat-induced immunosuppression.

Molecular cloning and expression characterization of translationally controlled tumor protein in silkworm pupae

A Bombyx mori (B. mori) cDNA was isolated from silkworm pupae cDNA library encoding a homologue of translationally controlled tumor protein (BmTCTPk). BmTCTPk was expressed in E. coli; SDS-PAGE and Western blot showed the molecular weight of recombinant and native BmTCTPk is approximately 28 and 25 kDa, respectively; they are larger than the theoretical molecular weight. Immunohistochemical studies showed that BmTCTPk is uniformly distributed throughout the cytoplasm of BmN cells. In silkworm pupae, BmTCTPk is expressed in the midgut wall, the midgut cavity, and some fat body tissues lying between the midgut wall and body wall. Western blot and ELISAs performed on total protein extracts isolated from silkworm pupae at different development stages showed that, although BmTCTPk is expressed during all pupae stages, its expression level increases dramatically during late pupae stages, suggesting that BmTCTPk may play an important role during the developmental transition from pupa to imago.

Alternaria alternata TCTP, a novel cross-reactive ascomycete allergen

Defining more comprehensively the allergen repertoire of the ascomycete Alternaria alternata is undoubtedly of immense medical significance since this mold represents one of the most important, worldwide occurring fungal species responsible for IgE-mediated hypersensitivity reactions ranging from rhinitis and ocular symptoms to severe involvement of the lower respiratory tract including asthma with its life-threatening complications. Performing a hybridization screening of an excised A. alternata cDNA library with a radioactively labeled Cladosporium herbarum TCTP probe, we were able to identify, clone and purify the respective A. alternata homologue of TCTP which again represents a multifunctional protein that has been evolutionarily conserved from unicellular eukaryotes like yeasts to humans and appears, summarizing current literature, to be involved in housekeeping processes such as cell growth as well as cell-cycle progression, the protection of cells against various stress conditions including for instance apoptosis, and in higher organisms even in the allergic response. In this context, our present study characterizes recombinant A. alternata TCTP as a novel minor allergen candidate that displays a prevalence of IgE reactivity of approximately 4% and interestingly shares common, cross-reactive IgE epitopes with its C. herbarum and human counterparts as determined via Western blotting and in vitro inhibition approaches.

Translationally controlled tumor protein is a novel heat shock protein with chaperone-like activity

Translationally controlled tumor protein (TCTP) is often designated as a stress-related protein because of its highly regulated expression in stress conditions. Following a thermal shock, TCTP expression is highly upregulated in a variety of cells. However, at present it is not known whether this upregulation has any cell protective function similar to other heat shock proteins. In this study human TCTP (HuTCTP) and a TCTP homolog (SmTCTP) from Schistosoma mansoni were evaluated for heat shock protein-like function and molecular chaperone activity. Our results show that similar to other molecular chaperones, both human and parasite TCTPs can bind to a variety of denatured proteins and protect them from the harmful effects of thermal shock. An important observation was the ability of both HuTCTP and SmTCTP to bind to native protein and protect them from thermal denaturation. Over expression of TCTP in bacterial cells protected them from heat shock-induced death. These findings suggest that TCTP may belong to a novel small molecular weight heat shock protein.

Transcriptome analysis of Schistosoma mansoni larval development using serial analysis of gene expression (SAGE)

SUMMARY

Infection of the snail, Biomphalaria glabrata, by the free-swimming miracidial stage of the human blood fluke, Schistosoma mansoni, and its subsequent development to the parasitic sporocyst stage is critical to establishment of viable infections and continued human transmission. We performed a genome-wide expression analysis of the S. mansoni miracidia and developing sporocyst using Long Serial Analysis of Gene Expression (LongSAGE). Five cDNA libraries were constructed from miracidia and in vitro cultured 6- and 20-day-old sporocysts maintained in sporocyst medium (SM) or in SM conditioned by previous cultivation with cells of the B. glabrata embryonic (Bge) cell line. We generated 21 440 SAGE tags and mapped 13 381 to the S. mansoni gene predictions (v4.0e) either by estimating theoretical 3' UTR lengths or using existing 3' EST sequence data. Overall, 432 transcripts were found to be differentially expressed amongst all 5 libraries. In total, 172 tags were differentially expressed between miracidia and 6-day conditioned sporocysts and 152 were differentially expressed between miracidia and 6-day unconditioned sporocysts. In addition, 53 and 45 tags, respectively, were differentially expressed in 6-day and 20-day cultured sporocysts, due to the effects of exposure to Bge cell-conditioned medium.

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.

Heat-inducible translationally controlled tumor protein of Trichinella pseudospiralis: cloning and regulation of gene expression

To elucidate the mechanism of inducing translationally controlled tumor protein (TCTP) in stress adaptation of adenophorean nematodes, the complete coding sequence of TCTP of the infective-stage larvae of Trichinella pseudospiralis was characterized. Two cDNA clones with different 3' untranslated region were identified. Tp-TCTP contained an open reading frame of 534 bp encoding 177 residues. The gene with five introns was expressed as histidine-tagged fusion protein having a molecular mass of 17.5 kDa. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that TCTP RNA was not accumulated when the infective-stage larvae were heat-shocked for 1 h at 45 or 60 degrees C. Using enzyme-linked immunosorbent assay and antiserum against the fusion protein, the expression of TCTP was found to be up-regulated at the translational level. The data suggest that translational regulation of TCTP may play an important role in the early heat-stress adaptation of the trichinellid. Cluster analysis demonstrated that the TCTP sequence of T. pseudospiralis is closely related to that of T. spiralis, but is diverged from the secernentean species.

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.

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.

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.

The fission yeast ES2 homologue, Bis1, interacts with the Ish1 stress-responsive nuclear envelope protein

In fission yeast, nutrient starvation induces physiological, biochemical, and morphological changes that enable survival. Collectively these changes are referred to as stationary phase. We have used a green fluorescent protein random insertional mutagenesis system to isolate two novel stress-response proteins required in stationary phase. Ish1 is a nuclear envelope protein that is present throughout the cell cycle and whose expression is increased in response to stresses such as glucose and nitrogen starvation, as well as osmotic stress. Expression of Ish1 is regulated by the Spc1 MAPK pathway through the Atf1 transcription factor. Although overexpression of Ish1 is lethal, cells lacking ish1 exhibit reduced viability in stationary phase. Bis1 is a novel interacting partner of Ish1. Bis1 is the Schizosaccharomyces pombe member of the ES2 nuclear protein family found in Mus musculus, Drosophila melanogaster, Homo sapiens, and Arabidopsis thaliana. Overexpression of Bis1 results in a cell elongation phenotype, whereas bis1(-) cells exhibit a reduced viability in stationary phase similar to that seen in ish1(-) cells.

Dioxin stimulates synthesis and secretion of IgE-dependent histamine-releasing factor

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD; dioxin) is the most toxic man-made member of the class of environmental pollutants represented by polychlorinated dibenzo-p-dioxins and dibenzofurans. TCDD produces a wide variety of toxic effects. However, the downstream genes targeted by TCDD and their relation to the diversity of dioxin toxicity symptoms are poorly understood. To identify the target genes of TCDD, we used a cDNA representational difference analysis (RDA) to compare the mRNA patterns of mouse embryonic stem (ES) cells that had and had not been exposed to TCDD. Here we show that TCDD stimulated the expression of IgE-dependent histamine-releasing factor (HRF) mRNA via an aryl hydrocarbon receptor (AhR)-dependent pathway. TCDD also induced the synthesis and secretion of HRF. To our knowledge, this is the first example of HRF being a direct transcriptional target of a toxic agent. HRF has previously been shown to induce histamine release in a dose-dependent manner, at least in vitro. Thus, our data suggest that "endocrine-disrupting" agents may have the potential to influence allergic disorders in the human body.

Cellular signalling and the complexity of biological timing: insights from the ultradian clock of Schizosaccharomyces pombe

The molecular bases of circadian clocks are complex and cannot be sufficiently explained by the relatively simple feedback loops, based on transcription and translation, of current models. The existence of additional oscillators has been demonstrated experimentally, but their mechanism(s) have so far resisted elucidation and any universally conserved clock components have yet to be identified. The fission yeast, Schizosaccharomyces pombe, as a simple and well-characterized eukaryote, is a useful model organism in the investigation of many aspects of cell regulation. In fast-growing cells of the yeast an ultradian clock operates, which can serve as a model system to analyse clock complexity. This clock shares strict period homeostasis and efficient entrainment with circadian clocks but, because of its short period of 30 min, mechanisms other than a transcription/translation-based feedback loop must be working. An initial systematic screen involving over 200 deletion mutants has shown that major cellular signalling pathways (calcium/phosphoinositide, mitogen-activated protein kinase and cAMP/protein kinase A) are crucial for the normal functioning of this ultradian clock. A comparative examination of the role of cellular signalling pathways in the S.pombe ultradian clock and in the circadian timekeeping of different eukaryotes may indicate common principles in biological timing processes that are universally conserved amongst eukaryotes.

Analysis of 114 kb of DNA sequence from fission yeast chromosome 2 immediately centromere-distal to his5

One hundred and fourteen kilobase pairs (kb) of contiguous genomic sequence have been determined immediately distal to the his5 genetic marker located about 0.9 Mb from the centromere on the long arm of Schizosaccharomyces pombe chromosome 2. The sequence is contained in overlapping cosmid clones c16H5, c12D12, c24C6 and c19G7, of which 20 kb are identical to previously reported sequence from clone c21H7. The remaining 93 781 bp of sequence contains 10 known genes (cdc14, cdm1, cps1, gpa1, msh2, pck2, rip1, rps30-2, sad1 and ubl1), 32 open reading frames (ORFs) capable of coding for proteins of at least 100 amino acid residues in length, one 5S rRNA gene, one tRNA(Pro) gene, one lone Tf1-type long terminal repeat (LTR) and one lone Tf2-type LTR. There is a density of one protein-coding gene per 2.2 kb and 22 of the 42 ORFs (52%) incorporate one or more introns. Twenty-one of the novel ORFs show sequence similarities which suggest functions of their products, including a cyclin C, a MADS box transcription factor, mad2-like protein, telomere binding protein, topoisomerase II-associated protein, ATP-dependent DEAH box RNA helicase, G10 protein, ubiquitin-activating e1-like enzyme, nucleoporin, prolyl-tRNA synthetase, peptidylprolyl isomerase, delta-1-pyrroline-5-carboxylate dehydrogenase, protein transport protein, coatomer epsilon, TCP-1 chaperonin, beta-subunit of 6-phosphofructokinase, aminodeoxychorismate lyase, a phosphate transport protein and a thioredoxin.

Expression of the gene and processed pseudogenes encoding the human and rabbit translationally controlled tumour protein (TCTP)

In humans and rabbits, the TPT1 gene encoding the translationally controlled tumour protein TCTP generates two mRNAs (TCTP mRNA1 and TCTP mRNA2) which differ in the length of their 3' untranslated regions. The distribution of these mRNAs was investigated in 10 rabbit and 50 human tissues. They were transcribed in all tissues investigated, but differed considerably in their quantity and ratio of expression. This indicates an extensive transcriptional control and involvement of tissue-specific factors. In the rabbit genome numerous processed, intronless pseudogenes were detected. Four, corresponding to both types of mRNAs, were sequenced and analysed in detail; all displayed only few mutations and were either preserved completely in the original amino acid sequence of the intron containing gene, or contained only minor mutations in the coding region which did not interrupt the open reading frame. In the mRNA population of rabbit reticulocytes two additional TCTP RNAs of the TCTP mRNA2 type were detected, which have the characteristics of pseudogene transcripts. Pseudogene transcription was supported further by CAT reporter gene assays showing substantial promoter activity of 5'-flanking regions of two TPT1 pseudogenes.