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Translationally controlled tumor protein (TCTP), also called histamine releasing factor (HRF) or fortilin, is a multifunctional protein present in almost all eukaryotic organisms. TCTP is involved in a range of basic cell biological processes, such as promotion of growth and development, or cellular defense in response to biological stresses. Cellular TCTP levels are highly regulated in response to a variety of physiological signals, and regulatory mechanism at various levels have been elucidated. Given the importance of TCTP in maintaining cellular homeostasis, it is not surprising that dysregulation of this protein is associated with a range of disease processes. Here, we review recent progress that has been made in the characterisation of the basic biological functions of TCTP, in the description of mechanisms involved in regulating its cellular levels and in the understanding of dysregulation of TCTP, as it occurs in disease processes such as cancer.

Background: Translationally controlled tumour protein TCTP is an anti-apoptotic protein frequently overexpressed in cancers, where high levels are often associated with poor patient outcome. TCTP may be involved in protecting cancer cells against the cytotoxic action of anti-cancer drugs. Here we study the early increase of TCTP levels in human colorectal cancer (CRC) and the regulation of TCTP expression in HCT116 colon cancer cells, in response to treatment with the anti-cancer drugs 5-FU and oxaliplatin. Methods: Using immunohistochemistry, we assessed TCTP levels in surgical samples from adenomas and adenocarcinomas of the colon, compared to normal colon tissue. We also studied the regulation of TCTP in HCT116 colon cancer cells in response to 5-FU and oxaliplatin by western blotting. TCTP mRNA levels were assessed by RT-qPCR. We used mTOR kinase inhibitors to demonstrate mTOR-dependent translational regulation of TCTP under these conditions. Employing the Real-Time Cell Analysis (RTCA) System and the MTS assay, we investigated the effect of TCTP-knockdown on the sensitivity of HCT116 cells to the anti-cancer drugs 5-FU and oxaliplatin. Results: 1. TCTP levels are significantly increased in colon adenomas and adenocarcinomas, compared to normal colon tissue. 2. TCTP protein levels are about 4-fold upregulated in HCT116 colon cancer cells, in response to 5-FU and oxaliplatin treatment, whereas TCTP mRNA levels are down regulated. 3. mTOR kinase inhibitors prevented the up-regulation of TCTP protein, indicating that TCTP is translationally regulated through the mTOR complex 1 signalling pathway under these conditions. 4. Using two cellular assay systems, we demonstrated that TCTP-knockdown sensitises HCT116 cells to the cytotoxicity caused by 5-FU and oxaliplatin. Conclusions: Our results demonstrate that TCTP levels increase significantly in the early stages of CRC development. In colon cancer cells, expression of this protein is largely upregulated during treatm

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 als

Translationally controlled tumour protein TCTP (gene symbol: TPT1) is a highly-conserved, cyto-protective protein implicated in many physiological and disease processes, in particular cancer, where it is associated with poor patient outcomes. To understand the mechanisms underlying the accumulation of high TCTP levels in cancer cells, we studied the signalling pathways that control translation of TCTP mRNA, which contains a 5′-terminal oligopyrimidine tract (5′-TOP). In HT29 colon cancer cells and in HeLa cells, serum increases the expression of TCTP two- and four-fold, respectively, and this is inhibited by rapamycin or mTOR kinase inhibitors. Polysome profiling and mRNA quantification indicate that these effects occur at the level of mRNA translation. Blocking this pathway upstream of mTOR complex 1 (mTORC1) by inhibiting Akt also prevented increases in TCTP levels in both HeLa and HT29 colon cancer cells, whereas knockout of TSC2, a negative regulator of mTORC1, led to derepression of TCTP synthesis under serum starvation. Overexpression of eIF4E enhanced the polysomal association of the TCTP mRNA, although it did not protect its translation from inhibition by rapamycin. Conversely, expression of a constitutively-active mutant of the eIF4E inhibitor 4E-BP1, which is normally inactivated by mTORC1, inhibited TCTP mRNA translation in HEK293 cells. Our results demonstrate that TCTP mRNA translation is regulated by signalling through the PI3-K/Akt/mTORC1 pathway. This explains why TCTP levels are frequently increased in cancers, since mTORC1 signalling is hyperactive in ~ 80% of tumours.

Cancer is a disease of uncontrolled growth and proliferation whereby cells have escaped the body's normal growth control mechanisms and have gained the ability to divide indefinitely. It is a multi-step process that requires the accumulation of many genetic changes over time (Figure 1). These genetic alterations involve activation of proto-oncogenes to oncogenes, deregulation of tumour suppressor genes and DNA repair genes and 'immortalisation' which will be discussed in this chapter.

We have employed a stable isotope- labelling approach to study the impact of rapamycin and mTOR kinase inhibitors (mTOR- Kls) on protein synthesis in Hela cells. As expected, rapamycin impaired the synthesis of proteins encoded by mRNAs containing S'- terminal oligopyrimidines (5'-TOPs), but, surpri singly, mTOR- Kls inhibited this much more strongly. Synthesis of several other proteins displayed the same pattern and, importantly, their mRNAs appear to contain a 5'- TOP, indicating they are novel members of this class of mRNAs. The mRNAs for translationally controlled tumour protein TCTP, an anti - apoptotic protein that is up- regulated by serum stimulation and in cancer, also contain a 5'-TOP. The seruminduced increase in TCTP levels is partially inhibited by rapamycin and completely by mTORKls. Polysome profile analysis combined with northern blotting revealed that these effects on TCTP and other novel 5' -TOP mRNA- encoded proteins are exerted at the translational level. Consistent with control by mTORCl, TCTP levels are not down- regulated by serumstarvation in mouse embryo fibroblasts lacking tuberous sclerosis complex 2 (TSC2). Although elF4E overexpression enhances the expression of TCTP and the polysomal association of other 5'-TOP mRNAs, it does not 'rescue ' their translation from the effects of mTOR inhibition, indicating that additional regulatory mechanisms account for th eir control by mTOR.

Background: In a traditional medical programme prior academic performance is a good indicator for success. We aimed to determine whether performance in year one correlated with undergraduate performance in Medical Science in our integrated curriculum. Summary of work: Prior performance in anatomy, biochemistry and physiology was accessed for students who had attended the University of Wollongong for their undergraduate studies. Performance was correlated with examination results achieved in year 1. Summary of results: Seventy six students enrolled in Medicine (2007-2010), had completed their undergraduate degree at UOW taking subjects in anatomy (n=63), biochemistry (n=69) or physiology (n=69). Prior performance in each discipline significantly correlated (P<0.0001) with overall performance in a year 1 integratedexamination (r2=0.33-anatomy, 0.21-biochemistry, 0.38- physiology). Current and prior performance was significantly correlated within each discipline, however, physiology (r2=0.31, P<0.0001) correlated more strongly than anatomy (r2=0.07, P=0.04) or biochemistry (r2=0.08, P=0.017). Conclusions: Undergraduate performance in medical sciences correlated with academic performance in year 1. Undergraduate performance in physiology had the strongest correlation, suggesting that learning in physiology was able to prepare students for learning in an integrated curriculum. Take-home messages: Prior academic performance in medical science can be predictors of student performance in first year medical exams.

The ‘translationally controlled tumour protein’ TCTP was originally discovered 30 years ago by researchers interested in proteins regulated at the translational level. Cloning and sequencing confirmed the conservation of this protein among all eukaryotic kingdoms, but did not reveal any functional clue, and TCTP was listed in the databases as a ‘family’ of its own. The functional characterisation of this protein extended over more than a decade, leading to a plethora of individual functions and interactions that have been ascribed to this protein. A major addition to the functional characterisation of TCTP was the identification in 1995 of its histamine releasing factor (HRF) activity in allergic conditions, which for the first time described an extracellular activity for TCTP in human disease. This triggered a host of additional publications aimed at characterising this HRF activity, which are discussed in other articles of this issue. Another milestone in the elucidation of TCTP’s function was the demonstration of its anti-apoptotic activity in 2001. Evidence is also accumulating for a role of TCTP in the cell cycle and in early development. This article provides an overview of the main cellular activities of TCTP. The second part will summarise our current knowledge on the mechanisms involved in regulating intracellular TCTP levels.

Signaling through mammalian target of rapamycin complex 1 (mTORC1) is stimulated by amino acids and insulin. Insulin inactivates TSC1/2, the GTPase-activator complex for Rheb, and Rheb.GTP activates mTORC1. It is not clear how amino acids regulate mTORC1. FKBP38 (immunophilin FK506-binding protein, 38 kDa), was recently reported to exert a negative effect on mTORC1 function that is relieved by its binding to Rheb.GTP. We confirm that Rheb binds wild type FKBP38, but inactive Rheb mutants showed contrasting abilities to bind FKBP38. We were unable to observe any regulation of FKBP38/mTOR binding by amino acids or insulin. Furthermore, FKBP38 did not inhibit mTORC1 signaling. The translationally controlled tumor protein (TCTP) in Drosophila was recently reported to act as the guanine nucleotide-exchange factor for Rheb. We have studied the role of TCTP in mammalian TORC1 signaling and its control by amino acids. Reducing TCTP levels did not reproducibly affect mTORC1 signaling in amino acid-replete/insulin-stimulated cells. Moreover, overexpressing TCTP did not rescue mTORC1 signaling in amino acid-starved cells. In addition, we were unable to see any stable interaction between TCTP and Rheb or mTORC1. Accumulation of uncharged tRNA has been previously proposed to be involved in the inhibition of mTORC1 signaling during amino acid starvation. To test this hypothesis, we used a Chinese hamster ovary cell line containing a temperature-sensitive mutation in leucyl-tRNA synthetase. Leucine deprivation markedly inhibited mTORC1 signaling in these cells, but shifting the cells to the nonpermissive temperature for the synthetase did not. These data indicate that uncharged tRNA(Leu) does not switch off mTORC1 signaling and suggest that mTORC1 is controlled by a distinct pathway that senses the availability of amino acids. Our data also indicate that, in the mammalian cell lines tested here, neither TCTP nor FKBP38 regulates mTORC1 signaling.

About 80 different ribosomal proteins are involved in the biogenesis and functioning of eukaryotic ribosomes. Genome sequencing efforts have contributed to our knowledge on their evolution, and recent progress in the structural analysis of the ribosome has considerably improved our understanding of the localization and function of individual ribosomal proteins, some of which are also involved in extraribosomal functions.