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Our previous studies have shown an essential role played by the octapeptide repeat region (OR) and the N‐terminal half of hydrophobic region (HR) in the anti‐apoptotic activity of prion protein (PrP). As PrP‐like protein Doppel (Dpl), which structurally resembles an N‐terminally truncated PrP, did not show any anti‐apoptotic activity, we examined apoptosis of HpL3–4 cells expressing Dpl fused to various lengths of the N‐terminal region of PrP to investigate whether the PrP/Dpl fusion proteins retain anti‐apoptotic function. HpL3–4 cells expressing Dpl fused to PrP(1–124) with the OR and N‐terminal half of HR of PrP showed anti‐apoptotic function, whereas Dpl fused to PrP(1–95) with OR did not rescue cells from apoptotic cell death induced by serum deprivation. These results indicate that the OR and N‐terminal half of HR of PrP retains anti‐apoptotic activity similar to full‐length PrP.

BackgroundPolymorphisms of the human prion protein gene (PRNP) contribute to the genetic determinants of Creutzfeldt-Jakob disease (CJD). Numerous polymorphisms in the promoter regions as well as the open reading frame of PRNP were investigated. Greater than 90% of Korean, Chinese, and Japanese carry the homozygote 129 MM codon. In Korea, polymorphisms have not been comprehensively studied, except codons 129 and 219 in PRNP among Korean CJD cases. Although polymorphisms at codons 129 and 219 play an important role in susceptibility to sporadic CJD, patients with other polymorphisms in PRNP exhibited critical distinctions of clinical symptoms.MethodsThe genetic analyses of PRNP were carried out among probable CJD patients in comparison with the results from magnetic resonance imaging (MRI) and electroencephalogram (EEG).ResultsThe molecular analyses revealed that three mutations at codons D178N, E200K, and M232R in heterozygosity. Patients with the D178N and M232R mutations had a 129MM codon, whereas the patient with the E200K mutation showed 129MV heterozygosity. They all revealed strong 14-3-3 positive signals. The 67-year-old patient with the D178N-129M mutation showed progressive gait disturbance and dysarthria was in progress. The 58-year-old patient with the E200K mutation coupled to the 129MV codon had gait disturbance, dysarthria, agitation, and ataxic gait, and progressed rapidly to death 3 months from the first onset of symptoms. The 65-year-old patient with the M232R mutation showed rapidly progressive memory decline and gait disturbance, and died within 16 months after onset of symptoms.ConclusionDespite differences in ethnicity, the clinical and pathological outcomes were similar to the respective mutations around the world, except absence of insomnia in D178N-129M subject.

Creutzfeldt-Jakob disease (CJD), included in the human transmissible spongiform encephalopathies (TSE), is widely known to be caused by an abnormal accumulation of misfolding prion protein in the brain. Human prion protein gene (PRNP) is mapped in chromosome 20p13 and many single nucleotide polymorphisms (SNPs) in PRNP have been discovered. However, the functionality of SNPs in PRNP is yet unclear, though several SNPs have been known as important mutation related with susceptibility human prion diseases. Our aim is to identify specific genotype patterns and characteristics in the PRNP genomic region and to understand susceptibility among Korean discriminated prion disease patients, suspected CJD patients and the KARE data group. Here, we have researched genotypes and SNPs allele frequencies in PRNP in discriminated prion disease patients group (n = 22), suspected prion diseases patients group (n = 163) and the Korea Association REsource (KARE) data group (n = 296) in Korea. The sequencing regions were promoter region, exon1 and exon2 with their junction parts among 481 samples. A total of 25 SNPs were shown in this study. Nucleotide frequencies of all SNPs are exceedingly tended to bias toward dominant homozygote types except in rs2756271. Genotype frequencies at codon 129 and 219 coding region were similar with previous studies in Korea and Japan. Pathogenic mutations such as 102P/L, 200E/K and 203V/I were observed in discriminated CJD patients group, and 180V/I and 232M/R were shown in suspected prion disease patients group and the KARE data group. A total of 10 SNPs were newly identified, six in the promoter region, one in exon 2 and three in the 3' UTR. The strong and unique linkage disequilibrium (D' = 0.94, r (2) = 0.89) was observed between rs57633656 and rs1800014 which is located in codon 219 coding region. We expect that these data can be provided to determine specific susceptibility and a protective factor of prion diseases not only in Koreans but also in East Asians.

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Based on serological assays, no transmission of HPAI A/H5N6 to humans was identified in this study cohort. Additional studies should be conducted to determine the possibility of poultry-to-human transmission of HPAI A/H5N6.