Study On The Interaction Of The Prion Gene Expression And Processes Of Transmissible Spongiform Encephalopathies

Transmissible spongiform encephalopathies (TSE) are a group of fatal neurodegenerative disorders of animals and humans, it is widely accepted that the conformational conversion of host-coded PrP~C into a relatively protease-resistant isoform PrP~SC (disease-associated form) which is the Pathogenesis of TSE. PtP~C serving as a substrate molecule and PrP~SC acting as a template in the development of the disease induce PrP~C conversion to PrP~SC; then the aggregation of PrP~SC in the central nervous system result in TSE. It is defining event to study the expression of PrP gene serving as a substrate molecule and has important sense to explore the mechanism of TSE. Now researches on the mechanism rely on the model of experimental animals and cultured neuronal cells. With the points of prion gene expression and its impaction on the development of TSE, we analyzed the prion gene expression of tissues of wild-type golden hamster, the animal model that golden hamster injected in brain by treated purified prion recombinant structure protein and the cultured neuronal cell model originate from SD rat. What we got will provide the foundational data for the mechanism of TSE and the function of prion protein. The content is as follows:1. The present work determined prion gene expression in CNS and peripheral tissues of normal golden hamster of varies ages to explor the expression model of the experimental animal. CNS tissues sampled included neocortex, cerebellum, thalamus and obex. Peripheral organs sampled included spleen and inguinal shallow lymph nodes with respect to lymphoid organs and heart, liver, kidney and lung. The results showed that the gene expression is higher in CNS tissues than that in peripheral organs and pertinent to ages. Tissue specific prion gene expression and dynamic variability is consistent with the function of prion protein in occurrence of TSE.2. Recombinant bovine prion protein was treated by chemical solution, and the treated Recombinant bovine prion protein was intracerebrally inoculated in the brain. The prion gene expression was quantified and the proteinase resistant protein was detected by western-blotting. The results showed that there was no difference between the experimental group and the control in prion gene expression and there also no difference in protein level at three detected sites in brain. Using the proteinase K to digest, there was no resistant protein occurred.3. Using the combination of physical and enzyme digested separate techniques and utilizing medication or different adhesion rates, cerebral neuron cells, astrocytes and cerebella granule neuronal cells were successfully separated, cultured and identified. All that provided the favorable experimental materials for research on mechanism of transmissible spongiform encephalopathies.4. To study the mechanism of neuronal degeneration and gliosis in transmissible spongiform encephalopathies, we constructed the cultured neuronal cells and astrocytes cells model by PrP~SC like prion protein peptide based on the proper principia. Quantification of the prion geneexpression and cells livabilities were studied for the cultured neuronal cells model. The results showed that the cultured cerebral neuron cells and cerebellar granule neurons had significant death that treated by the prion protein peptide at 50μM concentration while the cerebral astrocytes exhibited hyperplasia under the same circumstance. Under the same treatment regimens, the level of PrP gene expression was significantly down-regulated in cortical neuron cell cultures and cerebellar granule cell cultures and was up-regulated in astrocyte cultures. These findings indicate that PrP peptide regulates transcription of the PrP gene and this activity is associated with its neurotoxicity in primary rat neuronal cultures and the similar processes happened with the occurrence of the Transmissible spongiform encephalopathies.