The polypyrimidine tract binding protein (PTB) and its recently discovered homologue brain-enriched PTB (brPTB) are RNA binding proteins involved in the control of alternative splicing. We have characterized expression patterns of the PTB and brPTB in course of mouse brain development, using mRNA in situ hybridization. PTB is expressed in choroid plexi and ependyma at all the stages of development and temporarily in the mantle layer of migrating neuroblasts of fore-, mid- and hindbrain and in the external granular layer of cerebellum. In the neurons of adult mouse cerebrum and cerebellum expression of PTB is undetectable. In contrast to this, brPTB is expressed ubiquitously in neuroblasts of various parts of embryonic brain and in the differentiated neurons of postnatal cerebrum and cerebellum. brPTB mRNA is not observed in choroid plexi and ependymal layer. Thus, in the embryonic brain expression patterns of PTB and brPTB overlap, but in the course of brain development the patterns become complementary to each other.
During the period from 1986 to 1996, 1,665 cases of primary central nervous system (CNS) tumors were identified in the resident population of Estonia. Histological verification was available in 81% of the cases. Gliomas were more common in men, while meningiomas and neurinomas were more common in women. No significant difference was observed between the sexes for all primary CNS tumors. The age-specific incidence increased from the age of 30, reached a maximum in the age range of 50–69 years and declined in the elderly which may reflect under-diagnosis. The age-adjusted incidence rate for CNS tumors was 8.5/100,000 population. A comparison of our results with those of a previous study carried out in Estonia revealed a significant histology-specific increase in incidence in all age groups.
Tissue plasminogen activator (tPA) is increasingly recognized to play important roles in various physiological and pathological processes in the central nervous system (CNS). Much of the data on the involvement of plasminogen activators in neurophysiology and -pathology have been derived from studies on experimental animals. We have now performed a systematic characterization of the expression of tPA and its inhibitor, neuroserpin, in normal human CNS. Brain and spinal cord samples from 30-36 anatomic locations covering all major brain regions were collected at 9 autopsies of donors with no neurological disease. Tissues were embedded in paraffin and tissue arrays were constructed. In two cases parallel samples were snap-frozen for biochemical analysis. Expression and activity profiling of tPA and neuroserpin were performed by immunohistochemistry, in situ hybridization, immunocapture and zymography assays. In the adult CNS, tPA was expressed at the mRNA and protein levels in many types of neurons, in particular in thalamus, cortex of cerebellum, pontine nuclei, neocortex, limbic system, and medulla oblongata. Interestingly, tPA was often co-expressed with its CNS inhibitor, neuroserpin. Despite overlapping expression of tPA and neuroserpin, zymography and immunocapture assays demonstrated that human neural tissue is a rich source of active tPA. Our analysis documents a detailed map of expression of tPA and its inhibitor in the human CNS and is compatible with the view that tPA is a key player in CNS physiology and pathology.
Stromal extracellular matrix (ECM) components are thought to play an important role in regulating invasion of human gliomas. Macrophages and microglial cells may heavily influence the integrity of the extracellular compartment of gliomas, and the affected ECM may play a key role in regulating migratory activity of both tumor cells and macrophages/microglia. The aim of this investigation was to study immunohistochemically the expression patterns of four ECM components: fibronectin, laminin, collagen IV, and tenascin (TN) in human gliomas, with special attention to TN. Our main goal was to study the possible correlation between TN expression and macrophagic/microglial infiltration in gliomas. Altogether, 90 gliomas were studied. Tumors included 46 glioblastomas, 19 anaplastic gliomas, 22 low grade gliomas, and 3 pilocytic astrocytomas. Vascular TN prevailed in perinecrotic areas of glioblastomas, whereas interstitial TN was more often expressed distant from necrosis and in the ECM of anaplastic and low grade gliomas. Double staining with CD68 and anti-TN antibodies showed that macrophagic/microglial density was significantly higher in TN-positive areas of most of the glioblastomas and anaplastic gliomas, whereas microglial percentage from total number of CD68-positive cells was in most of the cases significantly higher in TN-negative areas. In addition, we saw a morphologically spatial correlation between higher densities of macrophagic/microglial infiltration and TN expression in perinecrotic areas in glioblastomas. Attachment of macrophages to TN-positive basement membrane zones of newly formed stromal blood vessels was evident. On the basis of our results, we conclude that TN may play a crucial role in regulating trafficking of cells of monocyte lineage in human gliomas.
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