Immunohistochemistry of glial reaction after injury in the rat: Double stainings and markers of cell proliferation

The astrocytic reaction in the rat after brain injury has been studied immunohistochemically for intermediate filaments (GFAP and vimentin), also with double staining procedures, and for markers of proliferation (BrdU and PCNA). GFAP-positive reactive astrocytes appeared around the lesion, where they were vimentin-positive and at a distance. BrdU and PCNA showed a high labelling index around the wound at day 2 and scattered positive nuclei were also found at a distance in the ipsilateral side. BrdU-positive astrocytes represented a minor fraction of GFAP- and vimentin-positive astrocytes. The expression of vimentin persisted at least 15 days after the lesion. Our results could suggest that distant reactive astrocytes originate through hypertrophy while those close to lesion arise by hyperplasia from mature or immature glial cells. The hypothesis is formulated that cells of the periventricular matrix contribute to the post-traumatic proliferative activity.     

Sequences in the proximal 5′ flanking region of the rat neuron-specific enolase (NSE) gene are sufficient for cell type-specific reporter gene expression

We investigated the regulation of the rat neuron-specific enolase gene using a transient transfection approach. Recent transgenic mouse studies have shown that a 1.8-kb segment of the ratNSE gene 5′ flanking region, including the first (noncoding) exon but not the first intron, is able to drive expression of a reporter gene in parallel with endogenousNSE. These data suggest thatcis-acting elements responsible for the spatial and temporal pattern ofNSE gene expression are located within the proximal 1.8 kb of the 5′ flanking sequence. To further investigate this region, we joined the 1.8-kb regulatory cassette to thecat reporter gene and generated a number of constructs in which the flanking sequence was progressively deleted from the 5′ end. These constructs were tested by transient transfection into neuronal and nonneuronal cells, followed by an assay for CAT activity. We found that as little as 255 bp of 5′ flanking sequence was able to confer cell type-specificity on the reporter gene. Further truncation to 120 bp of 5′ sequence resulted in a sharp downregulation of reporter activity in PC12 cells but a significant rise in both Neuro-2A neuroblastoma cells and nonneuronal Ltk- cells, indicating thatcis-acting elements controlling the regulation ofNSE in Ltk-, Neuro-2A, and PC12 cells may lie within the 135 bp region covered by this deletion. This region contains an AP-2 site and an element similar in sequence and position to a motif identified in the proximal promoter region of the neuron-specific peripherin gene. Reduction to 95 bp of 5′ sequence resulted in a slight downregulation of CAT activity in all cell lines tested, and further truncation to 65 bp of 5′ sequence caused a universal reduction to background levels of CAT activity, concomitant with the disruption of the basalNSE promoter. Our results show that the 5′ flanking region of theNSE gene is capable of conferring cell type-specificity on a heterologous gene in transfected cells and that elements responsible for this are located within the proximal 255 bp.     

视蛋白基因启动子的克隆和鉴定

目的 克隆出视蛋白基因启动子。方法 以小鼠全基因组为模板，用PCR法克隆出目的大小的片断。然后连接到T-载体上作酶切鉴定，最后测序。结果 酶切结果与预期相符，测序结果与公布序列完全一致。结论 视蛋白基因启动子克隆成功。     

Identification of a cis-acting positive regulatory element of the glial fibrillary acidic protein gene

Developmental regulation of astrocyte-specific expression of the glial fibrillary acidic protein (GFAP) gene reflects transition of immature glioblasts to mature astrocytes. Described here is the cloning and sequencing of the 5'-flanking region of the mouse GFAP gene. It contains a glial-specific positive cis-acting regulatory element that directs preferential expression of a linked reporter gene when transfected into GFAP-positive glioblastoma cells. Sequence analysis of this region revealed the presence of a putative AP-1 binding site, implying a possible role for AP-1 factors in the astroglial-specific expression of the GFAP gene.     

Altered genetic response to beta-adrenergic receptor activation in late passage C6 glioma cells.

Previous studies have demonstrated variability in the phenotype of rat C6 glioma cells. In the present study, we compared morphology, growth rate, and beta-adrenergic regulation of gene expression in early (P39-47) and late (P55-90) passage C6 cells. Morphological changes were observed in five independently derived, late passage populations. In four of the five, the untreated cells were more polygonal than the fibroblast-like parental cells, and only a small fraction exhibited process outgrowth after dbcAMP treatment. Untreated cells from the fifth late passage population had longer cytoplasmic processes than parental cells and responded to dbcAMP with further process outgrowth. All late passage populations had shorter generation times than the parental cells. In early passage cells, treatment with the beta-adrenergic agonist, isoproterenol (IPR), resulted in an increase in c-fos mRNA and a decrease in c-jun mRNA (Gu-bits RM, Yu H: J Neurosci Res, 30:625-630, 1991). Both of these immediate early gene responses were irreversibly lost between P50 and P55. Additional differences in basal or IPR-induced mRNA levels were observed for beta-APP, GFAP, NGF, and PPE, but not for a number of other mRNAs. These results are discussed in relationship to previously described differences in the ability of early and late passage C6 cells to accumulate cAMP (Mallorga P, et al.: Biochim Biophys Acta 678:221-229, 1981).     

Experimental Hydrocephalus in Suckling Hamster Induced by Myxovirus Infection

Abstract This study was undertaken to elucidate the pathogenesis of the hydrocephalus and aqueductal stenosis induced by intracerebral mumps virus inoculation in suckling hamsters.
Mild ventricular dilatation became apparent after 5 days of inoculation. Focal denuding of the ependymal layer and subsequent aqueductal stenosis were observed by 14 days after inoculation. The virus antigen was detected not only in the ependymal cells and choroid plexus, but also in some neurons in the cerebral cortex, hippocampus, midbrain and cerebellum. In the cerebral aqueduct, the orderly arrangement of the cilialy clusters was destroyed on the 5th day after inoculation. After 10 days, proliferation of GFAP positive cells was noticed around the cerebral aqueduct and subsequently caused aqueductal stenosis. In the advanced state of hydrocephalus, the cerebellum was displaced downward and showed an elongated, atrophic and sleevelike structure similar to the Arnold-Chiari malformation. It was suggested that the extensive damage of the ependymal cilia may account for early ventricular dilatation, and subsequent aqueductal stenosis with glial proliferation is the main cause of the advanced hydrocephalus. It has not yet been determined whether the mumps virus can pass through the human placenta or not. If it can, however, our results strongly suggest that mumps virus infection in the human fetus will cause congenital hydrocephalus.