PRNP Polymorphisms And Preliminary Study On Dentritic Cells Activated By PrP Peptides

Prion diseases are also called transmissible spongiform encephalopathies (TSEs), attributed to conformational conversion of the cellular prion protein (PrPc) into an abnormal conformer accumulating in the brain. TSEs or prion diseases are a group of fatal neurodegenerative disorders of animals and human,such as scrapie, BSE and CJD. PRNP polymorphisms are associated with species barriers, susceptibility, resistance and the incubation period of TSE. In this paper, the PRNP polymorphisms of three important local varieties were studied, not only it could supply or fill up the blank of Genomic Polymorphism database but also it is useful to variety improvement and TSEs prevention.Meanwhile, the thesis also studied substitution model PrP106-126 and their interaction with dendritic cells. It enriched much data of the prion intrusion mechanism and conformational change.PRNP cds were amplificated and cloned from three kinds of domestic animals after the venous blood of 89 Bactrian camels,30 Xiji donkeys and 112 Tan-sheep were taking into heparin anticoagulant tubes. We cloned and analyzed the PRNP sequences of 89 domestic Bactrian camels. The sequence analysis showed that the Bactrian camel PrP gene was consisted of an open reading frame of 770 nucleotides encoding 256 amino acids. The amino acid sequence of Bactrian camel PrP starts with the consensus sequence MVKSH, with almost identical amino acid sequence to the PrP of dromedary camels. A three octapeptide repeat region follows a nonapeptide in the N-terminal of deduced amino acid sequence from residues 54 to 95. Polymorphisms of PRNP in camels were observed in codons 16 (A→V),17(M→T),120 (N→S),176 (R→K),215(I→V),234 (S→Y),237 (Y→S), and 239 (Q→G) by comparing with other ruminants. The PrP gene nucleotide sequence alignments of Bactrian camels (HQ204566.1 and HQ204567.1) showed high identity with dromedary camel (99.2%,99.1%), sheep (91.9%,91.8%), and cattle (91.8%,91.6%). The prion protein (PrP) gene sequence and the deduced amino acid alignment of prion protein in Tan sheep were determined and variability of the PrP amino acids sequence were analyzed in this study. The sequence analysis showed that the Tan sheep PrP gene was consisted of an open reading frame of 768 nucleotides encoding 256 amino acids. The PrP nucleic acids and amino acids sequences of 112 Tan sheep were highly homogenous. The analysis of both sequences revealed that the most predominant allele at codons 136,154 and 171 in Tan sheep was ARQ (86.6%), AHQ (8.9%) and ARH (4.5%), which were known to be associated with high susceptibility to scrapie. The result suggests that Tan sheep is potentially susceptible to scrapie. The sequence analysis showed that the Xiji donkey PrP gene was consisted of an open reading frame of 768 nucleotides encoding 256 amino acids. Complete nucleotide sequences of the open reading frames of the 30 donkeys were obtained with a high identity (99.87%). The nucleotide substitutions were found at positions 153 (C→T),237 (T→C) and 354 (G→C) within Xiji donkey PrP genes respectively, which all were synonymous substitutions and the PrP amino acid sequences showed no diversity(100% identity). Sequence analysis revealed that the amino acid sequence of the Xiji donkey PrP starts with the consensus sequence MVKSH, characteristic of most of the species PrP. Xiji donkey PrP had five nonapeptides (octapeptides) repeat starting from 45 to 95 codons. Alignment also showed other polymorphisms at a number of residues, such as S100T, G101S, E171Q, V206I, K223R, Y225S, E226Q, F228Y, Q229Y, and V244I. There are only two protein polymorphisms among equus species mentioned in this study.the equus PRNP had less mutations but more hereditary stability than other species during mammalian evolution.DCs could release cytokines through NF-κB activation pathway after they were induced by PrP 106-126 peptides within 2 hours. The expressions of NF-κB proteins were associated with the peptide concentration. The NF-κB expression was mediated by the receptor for advanced glycation end products during being induced by the PrP106-126 peptides, because Olmesartan Medoxomil could inhibit this.