Tianhui Wang

Chronic noise exposure causes persistence of tau hyperphosphorylation and formation of NFT tau in the rat hippocampus and prefrontal cortex.

The non-auditory effects of noise exposure on the central nervous system have been established both epidemiologically and experimentally. Chronic noise exposure (CNE) has been associated with tau hyperphosphorylation and Alzheimers disease (AD)-like pathological changes. However, experimental evidence for these associations remains limited. The aim of the current study was to explore the effects of CNE [100 dB sound pressure level (SPL) white noise, 4 h/d×14 d] on tau phosphorylation in the rat hippocampus and the prefrontal cortex. Forty-eight male Wistar rats were randomly assigned to two groups: a noise-exposed group and a control group. The levels of radioimmunoprecipitation assay (RIPA)-soluble and RIPA-insoluble phosphorylated tau at Ser202, Ser396, Ser404, and Ser422 in the hippocampus and the prefrontal cortex were measured at different time points (days 0, 3, 7, and 14) after the end of the last noise exposure. Exposure to white noise for 14 consecutive days significantly increased the levels of tau phosphorylation at Ser202, Ser396, Ser404, and Ser422, the sites typically phosphorylated in AD brains, in the hippocampus and the prefrontal cortex. Tau hyperphosphorylation persisted for 7 to 14 d after the cessation of noise exposure. These alterations were also concomitant with the generation of pathological neurofibrillary tangle (NFT) tau 3, 7 and 14 d after the end of the stimulus. Furthermore, lasting increases in proteins involved in hyperphosphorylation, namely glycogen synthase kinase 3β (GSK3β) and protein phosphatase 2A (PP2A), were found to occur in close correspondence with increase in tau hyperphosphorylation. The results of this study show that CNE leads to long-lasting increases in non-NFT hyperphosphorylated tau and delayed formation of misfolded NFT tau in the hippocampus and the prefrontal cortex. Our results also provide evidence for the involvement of GSK3β and PP2A in these processes.

Overexpression of S100A4 is closely associated with the progression and prognosis of gastric cancer in young patients

The aim of this study was to determine the correlation of S100A4 expression with the progression, prognosis and clinical pathology of gastric cancer (GC) in young pateints. A total of 85 tumor tissues with corresponding adjacent normal tissues and 62 non-metastatic lymph nodes (LNs) with corresponding metastatic LNs were obtained from young GC patients (<40 years old) who underwent surgery between January 2001 and December 2006. The expression of S100A4 was detected by RT-PCR and immunohistochemistry. Differences in the expression of S100A4 mRNA or protein were observed among the GC tissues, matched normal gastric mucosa, non-metastatic LNs and metastatic LNs. The expression of S100A4 mRNA and protein in GC tissues and metastatic LNs was significantly higher compared with that in the matched normal gastric mucosa and non-metastatic LNs, respectively (P<0.05). The overexpression of S100A4 was significantly associated with parameters involved in tumor progression and poor prognosis, including tumor size (P=0.017), Lauren classification (P=0.002), histological classification (P= 0.010), histological differentiation (P= 0.000), Borrmann classification (P=0.020), tumor-node-metastasis (TNM) stage (P=0.000), LN metastasis (P=0.000) and distant metastasis (P=0.024). Multivariate analysis suggested that patient age (P=0.035), tumor size (P=0.002), TNM stage (P=0.001) and S100A4 upregulation (P=0.000) were independent prognostic indicators for the disease. The overexpression of S100A4 in young GC patients is significantly associated with the clinicopathological characteristics. S100A4 may be used as a biomarker to predict the progression and poor prognosis of GC in young patients.

Functional expression, characterization and application of the human S100A4 protein.

Preparations utilizing monoclonal antibodies against S100A4 provide useful tools for functional studies to investigate the clinical applications of the human S100A4 protein. In the present study, human S100A4 protein was expressed in Escherichia coli (E. coli) BL21 (DE3), successfully purified by diethylaminoethyl cellulose anion-exchange chromatography and identified by western blot analysis. Soluble S100A4 bioactivity was confirmed by Transwell migration and invasion assays in the human HeLa cell line. Monoclonal antibodies (mAbs) were generated utilizing the standard hybridoma method and were validated by enzyme-linked immunosorbent assay and western blot analysis. The antibody was then used to examine human gastric carcinoma specimens by immunohistochemistry. Recombinant S100A4 was functionally expressed in E. coli and promoted the migration and invasion of HeLa cells. Four hybridoma cell lines, which secreted mAbs specifically against human S100A4 protein, were obtained. One of the four mAbs, namely 2A12D10B2, recognized human S100A4 as indicated by immunohistochemical staining of human gastric carcinoma specimens and recombinant S100A4 was functionally expressed in E. coli. The mAbs of recombinant S100A4 were suitable for detecting S100A4 expression in human tissues and for investigating the subsequent clinical applications of the protein.

Protective effect and mechanism of rat recombinant S100 calcium‑binding protein A4 on oxidative stress injury of rat vascular endothelial cells

The aim of the present study was to examine the protective effects and mechanisms of S100 calcium-binding protein A4 (S100A4) on endothelial cell apoptosis induced by oxidative stress injury. Endothelial cells were cultured and divided into control and oxidative stress injury groups, with the latter state induced by H2O2. Endothelial cells in every group were incubated with or without 50 or 100 µM S100A4. The cell viability and amounts of malondialdehyde, nitric oxide and lactate dehydrogenase in the culture medium were measured. The apoptotic index was detected by TUNEL staining. Western blot and immunoprecipitation analyses were used to detect the expression levels and the association between S100A4 and P53. H2O2 treatment led to oxidative stress injury in the cultured vascular endothelial cells, a decrease in the cell viability and an increase in the rate of apoptosis of vascular endothelial cells compared with the negative control group. Exogenous S100A4 serves a significant function against oxidative stress injury (P<0.05), increasing the viability and attenuating the apoptotic rate of endothelial cells. Western blotting results suggested that the protein levels of S100A4 and P53 increased subsequent to oxidative stress injury and that exogenous S100A4 increased the expression of P53 in the cytoplasm and decreased the expression of P53 in nucleus. The immunoprecipitation assay results revealed a protein-protein interaction between S100A4 and P53. These results suggested that rat recombinant S100A4 serves an anti-apoptotic function in oxidative stress injury. This effect of S100A4 is mediated, at least in part, via the inhibition of the translocation of P53 to the nucleus.

Epigenetic upregulation of miR-126 induced by heat stress contributes to apoptosis of rat cardiomyocytes by promoting Tomm40 transcription

TOMM40 is the channel-forming subunit of a translocase of the mitochondrial outer membrane (TOM) that is essential for protein transport into mitochondria. TOMM40 plays an important role in maintaining normal mitochondrial function. The correlation between occupational thermal exposure and mitochondria dysfunction has been demonstrated; however, nothing is known about the alteration and role of TOMM40 in response to environmental heat stress. In the present study, we showed that environmental thermal exposure upregulated microRNA miR-126, consequently reducing AU-rich element RNA-binding protein 1 (AUF1)-mediated SP1 mRNA degradation and increasing TOMM40 transcription, which in turn decreased the mitochondria membrane potential and apoptosis of cardiomyocytes. Mechanistically, miR-126 upregulation was attributed to heat stress-induced promoter demethylation via elevated TET2 (Tet methylcytosine dioxygenase 2) expression, while SP1 mRNA degradation was caused by decreased translation of AUF1 induced by miR-126. Moreover, TOMM40 transcription was upregulated via increasing its transcription factor SP1 resulting from AUF1 inhibition in the heat stress responses. The results of the present study increased our understanding of the role of miR-126 and TOMM40 in heat stressed cardiomyocytes.

Electrodeposition of alginate with PEDOT/PSS coated MWCNTs to make an interpenetrating conducting hydrogel for neural interface

Abstract Neural interface is a critical component for the communication between the central nervous system and outside devices. But neural tissues withstand constant mechanical activity with outside devices which aggravates inflammation response. The investigation about soft interfacial modification materials for neural implants is a promising way to reduce the mechanical mismatch of neural tissues and implants. In this study, soft alginic acid gel and poly(3, 4-ethylenedioxythiophene)/poly(styrene sulfate)(PEDOT/PSS) coated multi-walled carbon nanotubes(MWCNT) was co-deposited on a microwire neural electrode, then PEDOT/PSS was electrochemically grown through the coating material to form a kind of soft interpenetrating networks (IPNs) for the improvement of neural interface. Compared to unmodified electrodes, the modified electrodes possess higher charge storage capacity (CSC) and lower electrochemical impedance, which would benefit the performance of stimulating and recording respectively. The IPNs are very soft after reswelling in brain tissue, and the cell experiment indicate its fantastic biocompatibility. Furthermore, acute neural recording experiments revealed that the IPNs reduced the noise floor. All these characteristics are greatly desired for the neural interface. Overall, we developed a soft interpenetrating conducting hydrogel coating material on the neural interface with excellent electrical and biological performance.

Functionally active rat S100A4 from a polymerase chain reaction-synthesized gene expressed in soluble form in Escherichia coli

S100A4 protein is associated with Ca2+-dependent regulation of intracellular activities and is significant in the invasion, growth and metastasis of cancer. In order to express rat S100A4 functionally and identify its biological activity following purification, an S100A4 gene fragment was optimized and fully synthesized via overlapping polymerase chain reaction. The gene was inserted into the prokaryotic expression vector, pBV220, with phage λ PRPL promoters following confirmation by DNA sequencing. The pBV220-S100A4 plasmid was constructed and transformed into Escherichia coli DH5α. Following temperature induction, rat S100A4 was overexpressed and the protein was observed to be located in the supernatant of the lysates, which was ~30–40% of the total protein within the host. The protein was isolated and purified by metal-chelate affinity chromatography. High purity protein (>98% purity) was obtained and in vitro western blot analysis identified that the recombinant S100A4 was able to bind to the antibody against wild-type S100A4. The bioactivity of the recombinant protein was detected via Transwell migration and invasion assays. The polyclonal antibody of rat S100A4 protein was prepared for rabbit immunization and exhibited similar efficacies when compared with commercial S100A4. Therefore, rat S100A4 was functionally expressed in E. coli; thus, the production of active recombinant S100A4 protein in E. coli may further aid with the investigation and application of S100A4.