Immunohistochemical Localization of Translationally Controlled Tumor Protein in Axon Terminals of Mouse Hippocampal Neurons.

Translationally controlled tumor protein (TCTP) is a cytosolic protein with microtubule stabilization and calcium-binding activities. TCTP is expressed in most organs including the nervous system. However, detailed distribution and functional significance of TCTP in the brain remain unexplored. In this study, we investigated the global and subcellular distributions of TCTP in the mouse brain. Immunohistochemical analyses with anti-TCTP revealed that TCTP was widely distributed in almost all regions of the brain including the cerebral cortex, thalamus, hypothalamus, hippocampus, and amygdala, wherein it was localized in axon tracts and axon terminals. In the hippocampus, TCTP was prominently localized to axon terminals of the perforant path in the dentate gyrus, the mossy fibers in the cornu ammonis (CA)3 region, and the Schaffer collaterals in the CA1 field, but not in cell bodies of granule cells and pyramidal neurons, and in their dendritic processes. Widespread distribution of TCTP in axon tracts and axon terminals throughout the brain suggests that TCTP is likely involved in neurotransmitter release and/or maintaining synaptic structures in the brain, and that it might have a role in maintaining synaptic functions and synaptic configurations important for normal cognitive, stress and emotional functions.

Up-regulation of Rhoa/Rho kinase pathway by translationally controlled tumor protein in vascular smooth muscle cells.

Translationally controlled tumor protein (TCTP), a repressor for Na,K-ATPase has been implicated in the development of systemic hypertension, as proved by TCTP-over-expressing transgenic (TCTP-TG) mice. Aorta of TCTP-TG exhibited hypercontractile response compared to that of non-transgenic mice (NTG) suggesting dys-regulation of signaling pathways involved in the vascular contractility by TCTP. Because dys-regulation of RhoA/Rho kinase pathway is implicated in increased vascular contractility, we examined whether TCTP induces alterations in RhoA pathway in vascular smooth muscle cells (VSMCs). We found that TCTP over-expression by adenovirus infection up-regulated RhoA pathway including the expression of RhoA, and its downstream signalings, phosphorylation of myosin phosphatase target protein (MYPT-1), and myosin light chain (MLC). Conversely, lentiviral silencing of TCTP reduced the RhoA expression and Rho kinase signalings. Using immunohistochemical and Western blotting studies on aortas from TCTP-TG confirmed the elevated expression of RhoA and increase in p-MLC (phosphorylated MLC). In contrast, down-regulation of RhoA and p-MLC were found in aortas from heterozygous mice with deleted allele of TCTP (TCTP+/-). We conclude that up-regulation of TCTP induces RhoA-mediated pathway, and that TCTP-induced RhoA plays a role in the regulation in vasculature. Modulation of TCTP may offer a therapeutic target for hypertension and in vascular contractility dysfunction.

Immunohistochemical localization of translationally controlled tumor protein in the mouse digestive system.

Translationally controlled tumor protein (TCTP) is a housekeeping protein, highly conserved among various species. It plays a major role in cell differentiation, growth, proliferation, apoptosis and carcinogenesis. Studies reported so far on TCTP expression in different digestive organs have not led to any understanding of the role of TCTP in digestion, so we localized TCTP in organs of the mouse digestive system employing immunohistochemical techniques. Translationally controlled tumor protein was found expressed in all organs studied: tongue, salivary glands, esophagus, stomach, small and large intestines, liver and pancreas. The expression of TCTP was found to be predominant in epithelia and neurons of myenteric nerve ganglia; high in serous glands (parotid, submandibular, gastric, intestinal crypts, pancreatic acini) and in neurons of myenteric nerve ganglia, and moderate to low in epithelia. In epithelia, expression of TCTP varied depending on its type and location. In enteric neurons, TCTP was predominantly expressed in the processes. Translationally controlled tumor protein expression in the liver followed porto-central gradient with higher expression in pericentral hepatocytes. In the pancreas, TCTP was expressed in both acini and islet cells. Our finding of nearly universal localization and expression of TCTP in mouse digestive organs points to the hitherto unrecognized functional importance of TCTP in the digestive system and suggests the need for further studies of the possible role of TCTP in the proliferation, secretion, absorption and neural regulation of the digestive process and its importance in the physiology and pathology of digestive process.

Expression and localization of translationally controlled tumor protein in rat urinary organs.

This study describes the very first assessment of the expression and localization of translationally controlled tumor protein (TCTP) in adult rat urinary organs. TCTP expression levels in kidneys, urinary bladder, and urethra were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, and its cellular localization was examined immunohistochemically in paraffin sections of various urinary organs. TCTP was found in all urinary organs. Its expression was high in the urethra and low in the bladder. TCTP was localized in glomerular podocytes, epithelium of proximal and distal renal tubules, in the loop of Henle, and in the transitional epithelium of the bladder and urethra, mostly in basal cell layers). The subcellular localization of TCTP in these urinary organs was cytoplasmic. These findings suggest that TCTP may be involved in urine formation and excretion.

Glutamine attenuates tubular cell apoptosis in acute kidney injury via inhibition of the c-Jun N-terminal kinase phosphorylation of 14-3-3.

OBJECTIVE: Tubular cell apoptosis is linked to the development of acute kidney injury (AKI), which is a frequent complication of traumatic rhabdomyolysis. The 14-3-3 protein, a multifunctional regulatory protein, binds a variety of apoptotic proteins and is a target of c-Jun N-terminal kinase (JNK) in the cell death signaling pathway. Therefore, we examined whether JNK phosphorylates 14-3-3 and downstream mitochondrial death pathway mediates apoptosis in myoglobinuric acute kidney injury to determine whether these events are regulated by glutamine, which is known to induce heat shock protein 70 (Hsp70), or involved in the synthesis of glutathione (GSH). DESIGN: A prospective, randomized, controlled animal trial. SETTING: University research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: We utilized a rat model of myoglobinuric AKI. Glutamine or saline was administered intraperitoneally before and after glycerol injection. Apoptotic cell death was determined via transferase-mediated deoxyuridine triphosphate nick-end labeling staining, and Hsp70, JNK, phospho-JNK, 14-3-3, phospho-14-3-3, and many other apoptotic proteins were examined via Western blot. Relative interactions between these proteins were tested by coimmunoprecipitation analyses. Also, GSH levels were determined to further test whether glutamine affects apoptotic cell death in myoglobinuric AKI. MEASUREMENTS AND MAIN RESULTS: Glutamine treatment elevated levels of Hsp70 or reduced GSH and attenuated tubular cell apoptosis in kidney tissues of rats with myoglobinuric AKI. Further, Hsp70 physically associated with JNK, thereby limiting its activation. In addition, JNK evidently interacted with 14-3-3, leading to its phosphorylation, Bad or Bax dissociation from 14-3-3, and subsequent Bax mitochondrial translocation and caspase activation in rats with acute renal failure. Glutamine treatment very modestly lowered elevated levels of serum creatinine in AKI rats. CONCLUSIONS: A signaling link between JNK and 14-3-3 and subsequent mitochondrial death pathway may partly act as an early signaling that promotes apoptotic cell death leading to AKI, and glutamine may at least partially prevent apoptosis via enhancing Hsp70 or GSH levels.