Prions:a threat to health security and the need for effective medical countermeasures

Prions are infectious conformations of certain naturally occurring proteins.These misfolded proteins can struc­turally alter healthy protein,creating misfolded copies that repeat the process and form protein aggregates that lead to neuronal cell death.Although years can pass from initial prion infection to clinical presentation of symp­toms,onset of symptoms is typically followed by rapid neurological decline resulting in death.Prion diseases have been characterized in animals ranging from sheep and cattle to cervids and humans,with notable cross-species infections such as the variant Creutzfeldt-Jakob disease.Thus,prions present a health risk with the potential to disrupt major food sources as well affect human health through animal to human and human to human trans­mission events.While human to human prion transmission is rare and the immediate risks for a prion-facilitated pandemic are low,prions are a class of pathogens for which we are underprepared.In addition,prions,and prion disease-like approaches,have also been discussed in the context of biological weapons and toxins,adding another layer of complexity surrounding biosecurity and biodefense.These threats underscore the need for increased scrutiny and research on prions.Here,pharmaceutical and nonpharmaceutical prion-specific interventions are discussed.Recent advances in prion therapeutic development are also briefly highlighted,and a set of policy rec­ommendations are given that aims to provide high level suggestions for the prevention and mitigation of prion diseases.

Prions朊病毒的研究进展

朊病毒(Proteinaceous Infectious Particales简称Prions)病是一种人和动物共患的亚急性海绵状脑病,其病原是一种具有传染性的不含核酸的病原体,故称为感染性朊病毒蛋白(PrP)。但它是如何复制成为异常PrPSc,并沉积在脑组织而引起发病,目前还是生物医学的一大课题,也是指引我们寻找治疗方案的思路。本文就朊病毒的历史背景、发病机制与症状等研究进展进行了综述,并就其预防措施及治疗方案提出了新的思路。

Major hotspots detected along the Scotia Ridge in autumn for southern right whales Eubalaena australis, Antarctic fur seals Arctocephalus gazella and Antarctic prions Pachyptila desolata

We investigated the role of hydrological features, such as water masses, fronts, eddies, and sea ice, in affecting the distribution of upper trophic level species in the Scotia Sea region during autumn. On board RV Polarstern, we performed 365 30-min strip transects recording seabirds and marine mammals along the North Scotia Ridge and the South Sandwich Trench in March--April 2013. Among the 7 identified cetacean species recorded, the humpback whale Megaptera novaeangliae was the most abundant baleen whale （40 individuals）, and noteworthy were sightings of six southern right whales Eubalaena australis. Pinnipeds （3 species, 1650 individuals） were dominated by Antarctic fur seal Arctocephalus gazella （99%）, and seabirds （36 species, 18900 individuals） by Antarctic prion Pachyptila desolata （-50%）. The distribution of these top predators was highly patchy with the majority of observations concentrated in a few counts. This heterogeneity is likely a result of prey availability, and we discuss how hydrological features may have caused the patchiness.

Techniques to elucidate the conformation of prions

Proteinaceous infectious particles(prions) are unique pathogens as they are devoid of any coding nucleic acid.Whilst it is assumed that prion disease is transmitted by a misfolded isoform of the cellular prion protein, the structural insight of prions is still vague and research for high resolution structural information of prions is still ongoing. In this review, techniques that may contribute to the clarification of the conformation of prions are presented and discussed.

Upregulated lncRNA PRNT promotes progression and oxaliplatin resistance of colorectal cancer cells by regulating HIPK2 transcription

BACKGROUND Colorectal cancer(CRC)is the third most common cancer and a significant cause of cancer-related mortality globally.Resistance to chemotherapy,especially during CRC treatment,leads to reduced effectiveness of drugs and poor patient outcomes.Long noncoding RNAs(lncRNAs)have been implicated in various pathophysiological processes of tumor cells,including chemotherapy resistance,yet the roles of many lncRNAs in CRC remain unclear.AIM To identify and analyze the lncRNAs involved in oxaliplatin resistance in CRC and to understand the underlying molecular mechanisms influencing this resistance.METHODS Gene Expression Omnibus datasets GSE42387 and GSE30011 were reanalyzed to identify lncRNAs and mRNAs associated with oxaliplatin resistance.Various bioinformatics tools were employed to elucidate molecular mechanisms.The expression levels of lncRNAs and mRNAs were assessed via quantitative reverse transcription-polymerase chain reaction.Functional assays,including MTT,wound healing,and Transwell,were conducted to investigate the functional implications of lncRNA alterations.Interactions between lncRNAs and trans-cription factors were examined using RIP and luciferase reporter assays,while Western blotting was used to confirm downstream pathways.Additionally,a xenograft mouse model was utilized to study the in vivo effects of lncRNAs on chemotherapy resistance.RESULTS LncRNA prion protein testis specific(PRNT)was found to be upregulated in oxaliplatin-resistant CRC cell lines and negatively correlated with homeodomain interacting protein kinase 2(HIPK2)expression.PRNT was demonstrated to sponge transcription factor zinc finger protein 184(ZNF184),which in turn could regulate HIPK2 expression.Altered expression of PRNT influenced CRC cell sensitivity to oxaliplatin,with overexpression leading to decreased sensitivity and decreased expression reducing resistance.Both RIP and luciferase reporter assays indicated that ZNF184 and HIPK2 are targets of PRNT.The PRNT/ZNF184/HIPK2 axis was implicated in promoting CRC progression and oxaliplatin resistance both in vitro and in vivo.CONCLUSION The study concludes that PRNT is upregulated in oxaliplatin-resistant CRC cells and modulates the expression of HIPK2 by sponging ZNF184.This regulatory mechanism enhances CRC progression and resistance to oxaliplatin,positioning PRNT as a promising therapeutic target for CRC patients undergoing oxaliplatin-based chemotherapy.

Therapeutic targeting of cellular prion protein: toward the development of dual mechanism anti-prion compounds

PrPSc,a misfolded,aggregation-prone isoform of the cellular prion protein(PrPC),is the infectious prion agent responsible for fatal neurodegenerative diseases of humans and other mammals.PrPSccan adopt different pathogenic conformations(prion strains),which can be resistant to potential drugs,or acquire drug resistance,posing challenges for the development of effective therapies.Since PrPCis the obligate precursor of any prion strain and serves as the mediator of prion neurotoxicity,it represents an attractive therapeutic target fo r prion diseases.In this minireview,we briefly outline the approaches to target PrPCand discuss our recent identification of Zn(Ⅱ)-Bn PyP,a PrPC-targeting porphyrin with an unprecedented bimodal mechanism of action.We argue that in-depth understanding of the molecular mechanism by which Zn(Ⅱ)-Bn PyP targets PrPCmay lead toward the development of a new class of dual mechanism anti-prion compounds.

Classical bovine spongiform encephalopathy and chronic wasting disease:two sides of the prion coin

Transmissible spongiform encephalopathies(TSEs)are a group of progressive and ultimately fatal neurologic diseases of man and animals,all resulting from the propagated misfolding of the host's normal cellular prion protein.These diseases can be spontaneous,heritable,anthropogenic/iatrogenic,or in some cases horizontally transmissible,and include such notable TSEs as bovine spongiform encephalopathy(BSE)of cattle and chronic wasting disease(CWD)of cervids.Although they are both unequivocally protein misfolding disorders,they differ markedly in their pathogenesis,transmissibility,and zoonotic potential.While the BSE epidemic has largely abated over the past three decades following global feed bans on ruminant meat and bone meal,CWD,which is readily transmitted through various forms of excreta,has rapidly expanded from its original endemic zone to encompass much of North America,along with recently identified foci in Scandinavia.Most importantly,although the classical form of BSE has proven transmissible to humans consuming contaminated beef or beef products,so far there have been no conclusive reports on the zoonotic transmission of cWD to humans.The underlying basis for these differences-whether host or agent directed-are not well understood,though may be due to inherent differences in the three-dimensional structure of the misfolded BSE or CWD prion proteins or the expression levels and tissue distribution of respective cellular prion proteins.With the uncontrolled geographic spread of CWD,it is imperative that we improve our understanding of the factors governing prion disease pathogenesis,transmission,and zoonotic potential.

Unraveling the molecular mechanism of prion disease:Insights fromα2 area mutations in human prion protein

Prion diseases are a class of fatal neurodegenerative diseases caused by misfolded prion proteins.The main reason is that pathogenic prion protein has a strong tendency to aggregate,which easily induces the damage to the central nervous system.Point mutations in the human prion protein gene can cause prion diseases such as Creutzfeldt-Jakob and Gerstmann's syndrome.To understand the mechanism of mutation-induced prion protein aggregation,the mutants in an aqueous solution are studied by molecular dynamics simulations,including the wild type,V180I,H187R and a double point mutation which is associated with CJD and GSS.After running simulations for 500 ns,the results show that these three mutations have different effects on the kinetic properties of PrP.The high fluctuations around the N-terminal residues of helix 2 in the V180I variant lead to a decrease in hydrogen bonding on helix 2,while an increase in the number of hydrogen bonds between the folded regions promotes the generation ofβ-sheet.Meanwhile,partial deletion of salt bridges in the H187R and double mutants allows the sub-structural domains of the prion protein to separate,which would accelerate the conversion from PrPC to PrPSc.A similar trend is observed in both SASA and Rg for all three mutations,indicating that the conformational space is reduced and the structure is compact.

Creutzfeldt-Jakob disease presenting as Korsakoff syndrome caused by E196A mutation in PRNP gene:A case report

BACKGROUND Prion diseases are a group of degenerative nerve diseases that are caused by infectious prion proteins or gene mutations.In humans,prion diseases result from mutations in the prion protein gene(PRNP).Only a limited number of cases involving a specific PRNP mutation at codon 196(E196A)have been reported.The coexistence of Korsakoff syndrome in patients with Creutzfeldt-Jakob disease(CJD)caused by E196A mutation has not been documented in the existing literature.CASE SUMMARY A 61-year-old Chinese man initially presented with Korsakoff syndrome,followed by rapid-onset dementia,visual hallucinations,akinetic mutism,myoclonus,and hyperthermia.The patient had no significant personal or familial medical history.Magnetic resonance imaging of the brain revealed extensive hyperintense signals in the cortex,while positron emission tomography/computed tomography showed a diffuse reduction in cerebral cortex metabolism.Routine biochemical and microorganism testing of the cerebrospinal fluid(CSF)yielded normal results.Tests for thyroid function,human immunodeficiency virus,syphilis,vitamin B1 and B12 levels,and autoimmune rheumatic disorders were normal.Blood and CSF tests for autoimmune encephalitis and autoantibody-associated paraneoplastic syndrome yielded negative results.A test for 14-3-3 protein in the CSF yielded negative results.Whole-genome sequencing revealed a diseasecausing mutation in PRNP.The patient succumbed to the illness 11 months after the initial symptom onset.CONCLUSION Korsakoff syndrome,typically associated with alcohol intoxication,also manifests in CJD patients.Individuals with CJD along with PRNP E196A mutation may present with Korsakoff syndrome.

疯牛病病原体研究及动物源性医疗器械产品安全性思考

目的介绍关于疯牛病的基本知识,并对哺乳动物源性医疗器械的安全性评价作简要介绍。方法查阅近年来对疯牛病、新克雅氏病、朊病毒的研究概况、检测方法、灭活方法,欧美等国对牛羊源性相关材料的控制措施以及国内对相关产品的管理方法相关的文献,综合分析。结果疯牛病,又称牛海绵状脑病(bovinespongiformencephacitis,BSE)。该病与羊瘙痒病具有同源性,它们与人类克-雅氏病(Creutzfeldt-Jakobdisease,CJD)均是海绵状脑组织病变,由Prion蛋白引起。疯牛病主要以缓慢破坏哺乳动物中枢神经系统为特征。结论由于动物源性医疗器械产品在原材料方面存在疯牛病等人畜共患疾病的风险,同时Prion蛋白对传统的杀灭方法有较强抵抗性,因此,加强对这类产品的源头控制及灭活工艺等生产质量体系的管理是非常重要的,从而保证动物源性医疗器械产品的使用安全有效。

PrP^c重组蛋白脑内接种金黄地鼠对mRNA表达的影响

为明确将牛PrPc重组蛋白接种金黄地鼠脑内是否引起异常临床表现、脑组织病理学变化及对其mRNA表达产生影响,为进一步研究PrPc蛋白与异构体PrPsc的结构转换机制提供基础数据,将纯化的牛PrPc重组蛋白磷酸盐缓冲液制剂进行地鼠颅内接种,约3μL/只,对照接种磷酸盐缓冲液(PBS);102 d后取出脑组织:一部分福尔马林固定后进行常规H.E.染色观察,另一部分提取脑组织总RNA,进行实时荧光定量RT-PCR检测。结果表明:处理未见临床异常表现;大脑、小脑、脑干组织病理学检测未见海绵状空泡变性和淀粉样斑;大脑PrPcmRNA表达水平无显著性差异。上述结果表明,用PrPc重组蛋白接种,在检测时间102 d内未引起金黄地鼠行为和脑组织的异常改变。

羊痒病概述

羊痒病(scrap ie)是传染性海绵状脑病(TSE)的原型,目前在世界许多地方流行。该病是绵羊的一种缓慢发展的致死性中枢神经系统变性疾病,能引起绵羊和山羊中枢神经系统发生退化变性,病羊具有中枢神经系统变性、空泡化、星形胶质细胞增生等特点,病羊表现为共济失调、痉挛、麻痹、衰弱和严重的皮肤瘙痒,病畜死亡率达100%。该病是由正常的朊蛋白(P rP c)发生错误折叠而变成异常的蛋白形式(P rP sc)引起的。

临床诊断散发型克雅病3例并文献复习

克雅病（Creutzfeldt-Jakob disease,CJD）又称皮质-纹状体-脊髓变性、亚急性海绵状脑病。是由异常朊蛋白（prion protein,Pr P）在脑内沉积引起的以进行性痴呆为主要症状的致死性疾病。其临床特点包括：起病隐匿,表现为进行性智能减退,伴有小脑、锥体系和锥体外系受损的症状和体征,病变累及到大脑皮质、丘脑、小脑、脑干和脊髓。

大熊猫朊病毒基因克隆与序列分析

根据已报道的哺乳动物朊病毒基因序列设计引物对，采用PCR方法扩增了大熊猫的朊病毒基因，将其克隆到T-Easy载体，序列测定及分析表明所克隆的大熊猫PRNP基因(GeneBank收录号为AF327449)片段为795bp，编码264个氨基酸的前体蛋白，推测其分子量约28．5ku。与已报道的牛(GeneBank收录号为AF455119)、绵羊(GeneBank收录号为AF367623)的相应序列作比较分析，核苷酸序列同源性分别为99％和83％，其编码的氨基酸同源性均为100％。在所克隆的大熊猫PRNP基因中未发现与朊病毒敏感性连锁的氨基酸多态性位点。