Lecture 5 Prion Diseasesmedicine.fudan.edu.cn/genetics/NPD/Assets/userfiles/sys... ·...
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Lecture 5Prion Diseases
David Saffen, Ph.D.Professor/Principal Investigator
Department of Cellular and Genetic MedicineFudan University, Shanghai, China
Email: [email protected]
Outline1. Introduction:
Transmissible spongiform encephalopathies (TSEs) aka “prion diseases”
2. Prion diseases in animals:ScrapieBovine spongiform encephalopathy (BSE)Additional TSEs in animals
3. Prion diseases in humans:KuruCreutzfeldt-Jacob Disease (CJD)New variant Creutzfeldt-Jacob Disease (vCJD)Gerstmann-Straussler-Scheinker disease (GSSD)Fatal Familial Insomnia (FFI)
4. Mechanisms of neurodegeneration in prion diseases5. Normal and adaptive functions of prion proteins6. Routes of prion infection and possible opportuities for early
intervention7. Prions and neurodegenerative diseases: common mechanisms
1. Introduction
Transmissible spongiform encephalopathies (TSEs) aka “prions diseases”
• Progressive, fatal neuro-degenerative diseases characterized by ataxia and dementia.
• Caused by “prions”: proteinaceous infectious particles
• The best characterized human prion is “prion protein” (PrP) a normal cellular protein that can undergo conformational changes to produce “self-replicating,” infectious variants
“Sponge-like” appearance of TSE brain;gliosis and loss of neurons are also characteristic of prion diseases
“normal” conformation
infectiousconformation
(Toxic!)
Key TSE and prion investigators
Daniel Carleton Gajdusek (NIH)1923-2008
Nobel Prize 1976Demonstrated that kuru agent
is infectious by transmitting the disease to monkeys
Stanley B Prusiner (UCSF-MS) b1942
Nobel Prize 1997Coined the word “Prion.”
Produced convincing experimentalevidence that prions are by themselves
“self-replicating” and infectious(i.e, independent of DNA or RNA).
Prevalence of human prion diseasesin the United States compared to other
neurodegenerative diseases (2000)
Prusiner SB, 2001
The prion gene (PRNP) and encoded protein (PrP)Human PRNP gene: Chr20p13
Processing, cellular location and putative functions of PrPC
• PrPC is translocated to the endoplasmic reticulum as 254-aa precursor; first and last 23 aa residues are removed, followed by addition of glycosyl-phosphatidylinositol (GPI)-anchor
• Mature protein is localized primarily on the outer surface of plasma membrane; enriched in neurons
• The functions of normal PrPc protein are unknown, although roles in the synapse formation, copper transport, and intracellular signaling have been proposed.
• Double-KO of PrP gene in mice is non-lethal
[ASN-linked]
Conformations and properties of “normal” and
pathogenic
forms of PrP
PrPC PrPSc
“cellular” “scrapie”
a-helix-rich b-sheet-rich
soluble* insoluble*
protease-sensitive
protease-resistant
*in nondenaturing detergents
2. Prion diseases in animals
Scrapie
• A fatal neurodegenerative disease of sheep and goats that was first recognized in Europe 250 years ago.
• Prototypic transmissible spongiform encephalopathy (TSE): causative agent is PrPSc.
• Transmission is thought to occur primarily through contact with placenta and placental fluids from infected ewes.
• Early symptoms include changes in behavior or temperament, scratching or rubbing body against fixed objects, loss of coordination, lip smacking and gait abnormalities.
• Susceptibility is influenced by polymorphisms in PrP gene; most infected sheep have the genotypes, 136VV, 136VA, or 171QQ
Bovine spongiform encephalitis (BSE)“mad cow disease”
• A fatal neurodegenerative disease in cattle characterized by spongiform degeneration of brain and spinal chord
• Transmission is thought to take place primarily by consumption of meat and/or brain-containing feed produced from contaminated cows and sheep
• Transmission to humans who ate meat from infected cattle during a major outbreak in Great Britain in the early 1980’s has been documented
• As of Oct 2009, over 200 human deaths had been linked to the consumption of contaminated beef. Over 4.4 million cows were destroyed in an effort to eradicate BSE in the British Isles.
Additional TSEs in animals
TSE disease Host
Prion
name
Prion
isoform
Chronic wasting
disease (CWD)
elk & deer CWD
prion
MDePrPsc
Feline spongiform
encephalopathy (FSE)
cats FSE
prion
FePrPsc
Transmissible mink
encephalopathy (TME)
mink TME
prion
MkPrPsc
Exotic ungulate
encephalopathy (EUE)
nyala &
greater
kudu
EUE
prion
NyaPrPsc
3. Prion diseases in humans
Kuru• A fatal disease characterized by progressive ataxia &
dementia; brains show spongiform neurodegeneration
• Associated with “mortuary rites” (ritualistic cannibalism) among Fore people of the Eastern Highlands Province of Papua New Guinea
• Kuru Epidemic in middle of the 20th century killed approximately 20% of Fore population: mostly women and children; epidemic ended following the banning of mortuary rites in 1960
• Causative agent is a self-propagating and infectious conformational variant of PrPc.
Papua New Guinea (PNG) Eastern Highlands Province (EHP)
Okapa Subdistrict
Fore tribe women suffering from kuru (1957)
The women are showing upper limb postures adopted to prevent postural tremors. From Philosophical Transactions of the Royal
Society B (Image: 2008 The Royal Society)
Population genetics of Kuru
• Homozygosity at PrP aa residue 129 (129MM or 129VV) is associated with early onset of kuru; by contrast, heterozygosity (129MV) is associated with late-onset or resistance to kuru.
• PrP 129M is the “ancestral” allele; the “derived” allele 129V is thought to have arisen about 500,000 years ago and has attained high frequencies in populations worldwide.
• It has been proposed that kuru-like epidemics have propelled the increase in 129V allele frequencies in these populations. Is this evidence for wide-spread cannibalism in human history?
• Heterozygosity at aa 127 (127GV) was also found to found to strongly correlate with protection against kuru in 129MMindividuals.
• An additional protective polymorphism, E219K, is found at high frequency in the Japanese population, where M129V is present at a very low frequency.
Fore women over the age of 50 who participated in mortuary feasts showed excess heterozygosity and
relatively low homozygosity for M129V
MM MV VV
Expected 8 15 7
Observed 4 23 3
c2 = [Oi-Ei]2/Ei = 8.267;
P = 0.003 (1 df)Fisher’s exact test: P = 0.01
Mead S et al, Science, 2003;Hedrick PW, Science, 2003
N x p2
30 x 0.266
N x 2pq
30 x 0.499
N x q2
30 x 0.233
Expected
(HWE)
8 15 7
p = f(M) = (8+8+15)/60 = 0.5167q = f(V) = (7+7+15)/60 = 0.4833N = 30
Haplotypes containing the 129M and 129V alleles are highly divergent in DNA sequence, suggesting an ancient split; the rapid rise of the 129V allele to high
frequencies in many population around the world may reflect “balancing selection.”
European
Japanese
ForeAfrican
Predicted haplotype geneaologies for four populations:Orange: 129MBlue: 129VPink: 129M, 219K
Note: a “kuru-resistant” PrP allelewas found in every population studied.
* Recent evidence has identified a secondprotective prion variant in the Fore population:G127V. Asante et al, Nature 522, 2015
M129V
11 majorEuropean haplotypes
Mead S et al, Science, 2003;
*
Creutzfeldt-Jacob Disease (CJD)Accounts for approximately 85% of prion disease cases: incidence =1-2/million in general population; Onset: 30-55 years; duration: several months to several years.
Histopathology includes: spongiform neurodegeneration, astrogliosis, and (in about 10% of cases) amyloid plaques containing PrPSc.
Most cases are sporadic and are caused by a spontaneous transition of PrPC to the PrPSc conformation; mutations identified in rare familialforms include: and R178N, V180I, E200K, R208H, V210I, & M232R.
Iatrogenic origins include, the therapeutic use of cadaveric human growth hormone, cornea or dura mater and reuse of surgical instruments or EEG electrodes; most victims of iatrogenic CJD are homozygous 129VV).
Spongiform degeneration Astrogliosis
Prusiner,2001
Variant Creutzfeldt-Jacob Disease (vCJD)
• Caused by eating meat from BSE-positive cows; causative agent is a self-propagating, infectious conformational variant of bovine PrPC (bPrPSc).
• Histopathology: spongiform degeneration; “florid plaques” composed of PrPSc surrounded by vacuoles.
• “Mad cow disease” epidemic in UK has claimed 176 victims to date, most homozygous MM129; M129/V129 heterozygotes seem to be protected.
• Sub-clinical infection in UK estimated at 1/2000! (Based on surveys of surgically removed appendices) Possible public health risk: blood trans-fusions, dentistry etc.
Spongiform degeneration “Florid plaques”
Gerstmann-Straussler-Scheinker (GSS) disease
• Autosomal dominant neurogenerative disorder; usually presents with cerebellar ataxia with pyramidal features, with dementia occurring later than in other prion diseases; onset of disease: 40-60; duration: 3-7 years
• Histopathology: dense core of amyloid surrounded by smaller globules of amyloid
• Caused by mutations in PrPC; identified mutations include: P102L, P105L, P105S, A117V, Y145Stop, N160Stop, F200K, & N217R
PrP amyloid plaques in cerebellum Visualization of plaques after hydrolytic
autoclaving and immunostaining
Fatal Familial Insomnia (FFI)
• Fatal autosomal dominant neurodegenerative disorder; usually presenting with untreatable insomnia, dysautonomia and dementia; selective degeneration of the thalamus; onset typically 40-50 yr; duration of illness: 12 to 16 months.
• Histopatholgy: neuron dropout and gliosis, especially in thalamus and inferior olivary nucleus of brain stem; relative lack of spongiform neurodegeneration
• Pathogenic mutations: R178N + 129M; R178Stop; sporadic cases with no known PrP mutations have also been reported.
Gliosis in thalamus(GFAP staining)
Summary of known human PrP mutations
and polymorphisms in inherited prion diseases
Lloyd, Mead, Collingwe, Brain, 2013
4. Mechanisms of neurodegenerationin prion diseases
Evidence that prions (protein-only) are the sole infectious agents in TSEs
Modified from Soto and Satani, 2010
The infectious agent is too small to be a virus or bacteria.
Infectivity is not blocked by treatments that destroy nucleic acids.
Injection of highly purified PrPSc induces prion disease in animals.
PrPSc is detected only in individuals with prion disease.
All inherited cases of prion disease are associated with PrP mutations.
Transgenic mice over expressing PrPC develop prion disease.
PrP knockout mice are resistant to prion infection.
PrPSc self-propagates in vitro by inducing the misfolding of PrPC.
PrPSc induces recombinant and purified PrPC to become infectious.
Differences between prion “strains” depend upon differences inprion folding
Mechanisms by which prions stimulate neurodegeneration
• The relatively mild pathologies observed in PrP KO mice suggest that loss of function is not the main mechanism
• Rather, the PrPSc form, by itself, or PrPSc in the form of higher molecular weight fibrils or aggregates are implicated
• The conversion of cellular membrane-anchored GPI-PrPC to the GPI-PrPSc form may also result in neurotoxic signaling that eventually kills the neuron to which it is attached.
Models for PrPSc propagation
Tuite MF and Cox BS, Nature Reviews Cell Biology 4, 878-890, 2003
Multiple neurodegenerative pathways mediate TSEs
Soto and Satani, 2010
Putative signaling pathways for PrPSc-induced neurodegeneration
Soto and Satani, 2010
Model for neurodegeneration in prion diseases
Soto and Satani, 2010UPR = Unfolded Protein Response
5. Normal and adaptive functions of prions
Putative roles for normal PrP(in mammals)
• Neuroprotection
• Anti-oxidation
• Binding of copper and other divalent cations, including Fe2+ (within the octapeptide repeat)
• Myelin maintenance
• Neurogenesis
• Circadian rhythm
• Sensitivity of brain to hypoxia, ischemia, seizures
• Immune system: T cell development, macrophage function, hematopoietic stem cell self-renewal
Yeast prions• The yeast translation termination factor Sup35 forms a prion state designated [PSI+], with reduced activity compared the “normal” [psi-] state.
• Cells that contain [PSI+] have different properties that promote survival in certain environments.
• In addition to Sup35,at least 8 additional yeast proteins form prions, including Rnq1, a protein that stimulates other proteins to convert to their prion forms.
Monitoring the [PSI+] prion by a simple color assay. The presence of the prion allows translation read-through of an aberrant stop codon in the ADE2 gene. The consequence of this is that prion-containing cells are white and cells lacking prions are red. (Gary Jones)
Prion epigenetics:
A. “Life-cycle of yeast amyloid
prion;
B. The effect of stress on prion formation and
loss
Halfmann& Lindquist,
2010
Prion phenotypes can result from either loss or gain of function
Prion strains:“mutation” and selection
Collinge J, 2010
Specific prion conformational states (oftencorrelated withdifferent prion aminoacid sequences) self-propagate, givingrise to prion “strains”with distinct bio-chemical propertiesand host range.
Rather thanmaintaining prionswith a specificconformation, however, hosts maymaintain a spectrumof prion states that can be transmitted to secondary hosts withdiffering efficiencies.
6. Routes of prion infection and possible opportunities for early intervention
Aguzzi, Nuvolone & Zhu,Nat. Rev. Immunol., 2013
Aguzzi, Nuvolone & Zhu, Nat. Rev. Immunol., 2013
Peripheral prion replication and the involvement of follicular dendritic cells (FDC)
Secondarylymphoid
Organs (SLOs)
TNFR: tumor necrosis factor (TNF)receptor
PDGFRb = platet-dirived growth factorreceptor-beta
LTa1b2: lymphotoxin-abhetero-trimer produced by lymphoid tissue inducer (LTi) cells or B cells
MFGE8: milk fat globule epidermalgrowth factor 8
FcyRIIB: low affinity immunoglobulin-g-Fc region receptor II-B
CD21, CD35: dendritic cell antigens
FDC = follicular dendritic cell
Prion-induced neuro-
degeneration and potential therapeutic
targets
Aguzzi, Nuvolone & Zhu,Nat. Rev. Immunol., 2013
Soluble (PrP-Fc)2 dimers act as decoys that prevent
the conversion of endogenous PrPC to PrPSc
2 x PrP (lacking GPI attachment sites)
Dimerized Fc domain(lacking FcR and complement
protein binding sites)
Meier P, et al, Cell 113, 49-60, 2003
Expression vector
Meier P, et al, Cell 113, 49-60, 2003
7. Prions and neurodegenerative diseases:common mechanisms
Basic mechanisms of protein aggregation
Brundin P et al, 2010
Potential pathways of uptake and release of
protein aggregates
by cells
Brundin P et al, 2010
Principles for progression of neuropathological changes
Brundin Pet al, 2010 ALS
FTLD
Evidence for prion-like properties of key proteins implicated in neurodegenerative diseases
Prusiner SB, Science 336, 2012
References• Prusiner SB, Shattuck Lecture--Neurodegenerative diseases and prions,
The New England Journal of Medicine 344, 1516-1525, 2001
• Wadsworth DF and Collinge J, Update on human prion disease, Biochimica et Biophysica Acta 1772, 598-609, 2007
• Westergard L et al, The cellular prion protein (PrPC): its physiological function and role in disease, Biochimica et Biophysica Acta 1772, 629-644, 2007
• Mastrianni JA, The genetics of prion disease, Genetics in Medicine 12, 187-194, 2010
• Loyd SE, Mead S, Collinge J, Genetics of prion diseases, Genetics and Development 23, 1-7, 2013
• Mead S et al, Balancing selection at the prion protein gene consistent with prehistoric epidemics, Science 300, 640-643, 2003
• Hendrick PH, A heterozygote advantage, Science 302, 57, 2003
• Soto C and Santani N, The intricate mechanisms of neurodegeneration in prion diseases, Trends in Molecular Medicine, in press, 2010
References• Collinge J, Prion Strain Mutations and Selection, Science 328, 1111, 2010
• Angers, RC et al, Prion strain mutation determined b prion protein conformational compatibility and primary structure, Science 328, 1154-1158, 2010
• Halfmann R & Lindquist S, Epigenetics in the extreme: prions and the inheritance of environmentally acquired traits, Science 330, 629-632, 2010
• Aguzzi A, Nuvolone M and Zhu C, The immunobiology of prion diseases, Nature Reviews Immunology 13, 888-902, 2013
• Kraus A, Groveman BR and Caughey B, Prions and the potential transmissibility of protein misfolding diseases, Annual Review Microbiology 67, 543-564, 2013
• Aguzi A and Rajendran L, The transcellular spread of cytosolic amyloids, prions and prionoids, Neuron 64, 783-790, 2009
• Brudin P et al, Prion-like transmission of protein aggregates in neurodegenerative diseases, Nature Reviews Cell Biology 11, 3001-3007, 2010
References• Kim J-S & Holtzman DM, Prion-like behavior of Amyloid-ß, Science 330,
918=919, 2010
• Eisele V et al, Peripherally applied Ab-containing inoculates induce cerebral b-amyloidosis, Science 330, 980-982, 2010
• Masuda-Suzukake M, et al, Prion-like spreading of pathological a-synuclein in brain, Brain, January 13, 1-11, 2013
• Prusiner SB, A unifying role for prions in neurodegenerative diseases, Science 336, 1511-1513, 2012
• Lahiri DK, Prions: a piece of the puzzle?, Science 336, 1172, 2012
• Kim HJ et al, Mutations in prion-like domains in hnRNPA2B1 and hnRNPA1 cause multisystem proteinopathy and ALS, Nature 495, 467-473, 2013
• King OD, Gitler AD, Shorter J, The tip of the iceberg: RNA-biding proteins with prion-like domains in neurodegenerative disease, Brain Research 1462, 61-80, 2012
Journal Presentation
• Background articles:
1) Palfreman J, The Virus That Could Cure Alzheimer’s, Parkinson’s,
and More, Nova next, Public Broadcasting Service, March 23, 2016
2) Coghlan A, Universal plaque-busting drug could treat various brain
diseases, Daily News, New Scientist, July 19, 2015
• Research article:
Krishanan R et al, A bacteriophage capsid protein provides a
general amyloid interaction motif (GAIM) that binds and remodels
misfolded protein assemblies, Journal of Molecular Biology 426,
2500-2519, 2014
Internet resources
• World Health Organization http://www.who.int/zoonoses/diseases/prion_diseases/en/
• National Institute of Allergy and Infectious Diseases (NIH) http://www.niaid.nih.gov/topics/prion/Pages/default.aspx
• Centers for Disease Control and Prevention http://www.cdc.gov/ncidod/dvrd/prions/
• National Prion Disease Pathology Surveillance Center
• http://www.cjdsurveillance.com/