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

Translationally controlled tumor protein restores impaired memory and altered synaptic protein expression in animal models of dementia

This study describes the effects of translationally controlled tumor protein (TCTP) on mice with memory impairment caused by scopolamine (SCO) administration. Specifically, memory functions and expression levels of hippocampal synaptic proteins in 7- to 12-month-old SCO-treated wild-type (WT-SCO) mice were compared to those of TCTP-overexpressing (TG) and TCTP knocked-down (KD) mice similarly treated with SCO. Passive-avoidance tasks were performed with WT, TG, and KD mice for four weeks after intraperitoneal injection of SCO or saline followed by an acquisition test. After completing behavioral studies, hippocampi of all mice groups were collected and their synaptic protein contents were subjected to Western blotting or immunohistochemical analyses, and compared with those of 5x familial Alzheimer's disease (5xFAD) mice and postmortem AD patients. Results of passive avoidance tests revealed that SCO-induced memory impairment was repaired in TCTP-TG mice, but not in TCTP-KD mice. Hippocampal expression levels of synaptophysin, synapsin-1, and PSD-95 were increased in TCTP-TG mice treated with SCO (TG-SCO) but decreased in TCTP-KD mice treated with SCO (KD-SCO). Decreased levels of TCTP, synaptophysin, and PSD-95 were also found in hippocampi of 5xFAD mice and AD patients. Expression levels of p-CREB/CREB and brain-derived neurotrophic factor (BDNF) in TCTP-TG and TG-SCO mice were similar to or increased compared to those in WT mice, but decreased in TCTP-KD and KD-SCO mice. BDNF immunoreactivity was restored in CA1 regions of hippocampi of TG-SCO mice, but not in KD-SCO mice. These results suggest that TCTP can restore damaged memory in mice possibly through restored synaptic protein expression.

Dysregulation of TCTP in Biological Processes and Diseases

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.

Downregulation of transcription factor TCTP elevates microRNA-200a expression to restrain Myt1L expression, thereby improving neurobehavior and oxidative stress injury in cerebral palsy rats

Transcription factors have already been proposed to work on some human diseases. Yet the role of translationally controlled tumor protein (TCTP) in cerebral palsy (CP) remains elusive. This study intends to examine the mechanism of TCTP on CP by regulating microRNA-200a (miR-200a).CP models of rats were established referring to the internationally recognized improved hypoxic ischemic encephalopathy modeling method. The neuroethology of rats, ultrastructure and pathological condition in brain tissues of rats were observed through several assays. The expression of TCTP, miR-200a, myelin transcription factor 1-like (Myt1L), tyrosine hydroxylase (TH) and inducible nitric oxide synthase (iNOS) along with apoptosis in brain tissues of rats was detected. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in brain tissues of rats were determined. The binding site between miR-200a and Myt1L was analyzed.TCTP and Myt1L were overexpressed and miR-200a was under-expressed in CP rats. Elevated miR-200a ameliorated neurobehavior of CP rats and pathological injury in brain tissues. Elevated miR-200a up-regulated TH, GSH, GSH-Px, and SOD levels, down-regulated iNOS, ROS, MDA, TNF-α, and IL-6 levels, and attenuated neuronal apoptosis in brain tissues of CP rats. Myt1L was a target gene of miR-200a.Altogether, our study suggested that diminution of transcription factor TCTP up-regulates miR-200a to limit Myt1L expression, thereby improving neurobehavior and oxidative stress injury in CP rats.