Molecular Brain Research最新文献

The motor neuron-like cell line NSC-34 has become a widely used in vitro model for motor neuron biology and pathology. We established a tetracycline-regulated gene expression system in this cell line by stably transfecting pTet-Off, which codifies for the tetracycline transactivator, the regulatory protein tTA. The monoclonal cell lines (NSC-34-tTA) were evaluated for the presence of functional tTA after transient transfection with pBI-EGFP, analyzing the expression of the reporter gene enhanced green fluorescent protein. We evaluated the regulation of tTA function with doxycycline using fluorescence microscopy and quantitative cytofluorimetric analysis on viable transfected cells. The best-regulated cell line (NSC-34-tTA40) had a 66.4-fold induction for the reporter gene fluorescence in comparison to NSC-34.

Alpha-tubulin, GAP-43 and phosphorylated medium and heavy neurofilaments, proteins of importance for the motor neuronal phenotype, were evident in NSC-34-tTA40 by Western blot and immunocytochemistry; they were expressed similarly in NSC-34-tTA40 and in NSC-34.

The cDNA of human Cu/Zn superoxide dismutase, a gene of interest for amyotrophic lateral sclerosis, was cloned into pBI-EGFP, downstream of the tetracycline-responsive bidirectional promoter. This plasmid was transiently transfected into NSC-34-tTA40, and the functionality of bidirectional transcription was verified by determining the expression of enhanced green fluorescent protein and of human Cu/Zn superoxide dismutase. Both proteins were regulated by doxycycline.

This novel cell line, NSC-34 tTA40, that permits tetracycline-regulated gene expression may prove useful to unravel the mechanisms of motor neuron degeneration.

We searched for a gene that is up-regulated in response to LPS at a later time point in primary cultured glial cells. Using a Gene Chip Probe Array, we identified stefin A3, which is known as a cysteine protease inhibitor. As assessed by RT-PCR, we observed a time-dependent (2 to 48 h) up-regulation of stefin A3. The results indicate that stefin A3 is involved in infection and inflammation at a later time point.

Diffuse infiltrating gliomas are the most common tumors of the central nervous system (CNS), naturally progressing from a lower-grade to a higher-grade malignancy. Several genetic alterations have been correlated with astrocytic tumors; however, a number of as yet unknown genes may also be involved. Therefore, we set out to search for genes that are differentially expressed in anaplastic astrocytoma and normal CNS tissue by applying a PCR-based subtractive hybridization approach, namely, representational difference analysis (RDA). The results of DNA sequencing of a sample (96 cDNA clones) from the subtracted library allowed the identification of 18 different genes, some of which were represented by several cDNA clones, coding for the Np95, LMO1, FCGBP, DSCAM, and taxilin proteins. Quantitative real-time PCR analysis for five of these genes was performed using samples of astrocytic tumors of different grades, confirming their higher expression when compared to non-tumoral CNS tissue. Identification of differentially expressed genes present in gliomas but not in normal CNS tissue is important not only to better understand the molecular basis of these cancers, but also to generate diagnostic DNA chips, which may be useful in future therapeutic intervention.

NAPOR-3 is a central nervous system RNA binding protein that is associated with downstream mRNA targets and has been demonstrated to be selectively overexpressed during apoptotic cell death. In this study, we first examined the regional distribution of NAPOR-3 mRNA in the adult rat brain by in situ hybridization: the transcript was abundantly expressed in many brain regions, mostly in gray matter, including the CA1–CA4 regions and dentate gyrus of the hippocampus, the piriform cortex and the cerebellar granule cell layer. We then investigated the role of NAPOR-3 in neuronal cell death by monitoring its mRNA and protein expression levels using semiquantitative RT-PCR and Western blotting, respectively. NAPOR-3 was overexpressed in rat organotypic slices exposed to staurosporine and to oxygen–glucose deprivation (OGD), an in vitro model of apoptotic cerebral ischemia, but not when exposed to glutamate toxicity. Our results also demonstrate that NAPOR-3 gene overexpression is an early step in the chain of signaling events leading to apoptosis, taking place upstream of caspase-3 activation. Finally, antisense-mediated downregulation of NAPOR-3 gene expression protected hippocampal cultures against OGD-induced apoptosis and prevented caspase-3 activation. Our results demonstrate that NAPOR-3 gene overexpression is necessary for the execution of OGD-induced programmed cell death.

Oxidative stress (OS) causes extensive cell death in the CA1 but not the CA3 region of the hippocampus. We found that the CA1 region of hippocampus explants, cultured under normal conditions, had significantly higher superoxide levels and expressed both anti-oxidant genes and genes related to the generation of reactive oxygen species at significantly higher levels than the CA3. These observations were indicative of high intrinsic OS in CA1.

Brain Derived Neurotrophic Factor (BDNF) plays an important role in brain development and plasticity. BDNF gene expression is known to be dynamically regulated during development, but the regulatory controls of normal differential expression are not well understood. Methylation of CpG dinucleotides within gene promoters is emerging as an important epigenetic control mechanism of transcription, and the BDNF complex promoter contains several CpG dinucleotides. We determined BDNF expression in the developing mouse forebrain and examined whether there were correlated patterns of methylation at CpG dinucleotides within the BDNF promoter. The data show that BDNF is dynamically expressed in the mouse forebrain and that expression is correlated with differential methylation specifically at CpG dinucleotides in eIV of the mouse BDNF promoter. These studies demonstrate that DNA methylation of this regulatory region may be an important mechanism controlling differential expression of BDNF during forebrain development.

In this study, we tested changes of internal standard genes of the brain after electrical tail shock in rats. The level of 28S rRNA of the amygdala was increased significantly after the stress. There was no significant change in GAPDH, β-actin, 36B4 mRNA and 28S rRNA at the subfornical organ and the hippocampus.

Beta-amyloid peptide (Aβ) is considered responsible for the pathogenesis of Alzheimer's disease (AD). Several lines of evidence support that Aβ-induced cytotoxicity is mediated through the generation of reactive oxygen species (ROS). Thus, agents that scavenge ROS level may usefully impede the development or progress of AD. Green tea extract has been known to have such antioxidant properties. Our previous studies demonstrate that green tea extract protected ischemia/reperfusion-induced brain cell death by scavenging oxidative damages of macromolecules. In this study, we investigated the effects of green tea extract on Aβ-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. PC12 cells treated with Aβ_25–35 (10–50 μM) showed intracellular ROS elevation, the formation of 8-oxodG (an oxidized form of DNA), and underwent apoptotic cell death in a dose-dependent manner. Aβ_25–35 treatment upregulated pro-apoptotic p53 at the gene level, and Bax and caspase-3 at the protein level, but downregulated anti-apoptotic Bcl-2 protein. Interestingly, co-treated green tea extract (10–50 μg/ml) dose-dependently attenuated Aβ_25–35 (50 μM)-induced cell death, intracellular ROS levels, and 8-oxodG formation, in addition to p53, Bax, and caspase-3 expression, but upregulated Bcl-2. Furthermore, green tea extract prevented the Aβ_25–35-induced activations of the NF-κB and ERK and p38 MAP kinase pathways. Our study suggests that green tea extract may usefully prevent or retard the development and progression of AD.

Mice lacking the D₂ dopamine receptor (D₂^−/−) and congenic to the C57BL/6J background were tested for opioid-mediated locomotor activity to examine the involvement of the D₂ dopamine receptor in opioid pharmacology. Morphine-stimulated locomotor activity did not significantly differ between the two genotypes. The opioid antagonist naloxone dose-dependently decreased spontaneous motor activity in wild-type mice but was without significant effect in D₂^−/− mice. The magnitude of food-conditioned increases in locomotor activity in wild-type mice and D₂^−/− mice was similar but naloxone did not decrease conditioned motor activity in D₂^−/− mice. Spontaneous locomotor activity of mice lacking the endogenous opioids β-endorphin and/or enkephalin was also tested and we found that naloxone did not reduce activity in mice specifically lacking enkephalin. We suggest that the D₂ dopamine receptor is necessary for modulation of spontaneous locomotor activity stimulated by the endogenous opioid enkephalin.