To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation.
We have compared the immunomorphological spectrum of the deposition of the disease-associated prion protein (PrP(Sc)) in the cerebral and cerebellar cortex of 32 Creutzfeldt-Jakob disease (CJD) patients with the PrP gene (PRNP) E200K mutation to 45 sporadic CJD and 14 other genetic prion disease cases.
Expression of the prion protein gene (Prnp) and production of the PrP protein are essential requirements for acquisition and spread of transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease (CJD) in humans.
The PrP gene of the host exerts a major influence over the outcome of transmissible spongiform encephalopathy (TSE) disease, but the mechanism by which this is achieved is not understood.
This review focuses on PrP gene knockout and gene replacement studies, PrP structure and function, and transgenic models of human and animal prion diseases.
Among the dozen known mutations in the PrP gene which segregate with the inherited prion diseases, only 2 mutations have been described in Israel so far: the codon 200 mutation in Creutzfeldt-Jakob disease (CJD) affected Libyan Jews, and the codon 102 mutation in 1 Jewish Gerstmann-Straussler-Scheinker (GSS) affected pedigree of German origin.
Progress has been made in understanding inherited prion diseases by genetically linking clusters of familial CJD (fCJD) to mutations of the PrP gene (PRNP).
A number of lines of biochemical evidence implicate the disease-specific isoform, PrPsc, as the transmissible agent and genetic analysis has shown tight linkage between PrP gene mutations and polymorphisms and differential susceptibility to prion diseases, Perhaps the strongest evidence for a protein-only model of the agent is that PrP gene-ablated mice are resistant to scrapie and that mice with PrP mutation, corresponding to those found in a human familial prion disease, spontaneously develop a transmissible prion disease.
Age at disease onset and rate of progression of transmissible spongiform encephalopathies in man, sheep and mice are modulated by the host genome, in particular by the PrP gene and its allelic forms.
There were no mutations found in the Prp gene, so it is possible that there are SEs caused by genes or other pathological processes unrelated to the Prp gene.
The pathogenic PrP protein accumulating in the brain of TSE patients is a protease-resistant and insoluble product of a precursor protein molecule of unknown function that is encoded by the PRNP gene on chromosome 20.
The identification of pathogenic PrP alleles and the role of the codon 129 PrP gene polymorphism in determining susceptibility to prion disease provides strong support for the idea that an abnormal isoform of PrP, PrPSc, is the principal constituent of the prion and that its propagation involves direct PrP-PrP interactions which occur most readily between identical PrP molecules.
Growth factors like NGF are known to increase the expression of PrP gene, a housekeeping gene which is responsible for susceptibility to transmissible spongiform encephalopathies.