30511
DESCRIPTION
NMNTRANSCRIPT
![Page 1: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/1.jpg)
PRIONS PRIONS
THE THE
INFECTIOUS PROTEINSINFECTIOUS PROTEINS
Paras Yadav*, Jaspreet Singh Arora*, Sachinandan De*, Tirtha Kumar Datta*, Surender Lal Goswami*, Aarti Bhardwaj$, Shalini Jain# and Hariom Yadav#
*Animal Biotechnology, #Animal Biochemistry Division, National Dairy Research Institute, Karnal-132001, Haryana, India
$Meerut Institute of Engeenering and Technology, Meerut, U.P., India
![Page 2: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/2.jpg)
• Stanley B. Prusiner coined the term proin from Proteinaceous infective particle
and changed to prion to sound it rhythmic.
• Prion diseases were caused by misfolded proteins.
• Elucidated the gene and mechanism by which wild type protein bring about the
clinical disease.
INTRODUCTION
![Page 3: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/3.jpg)
• Kuru
• Fatal Familial Insomnia (FFI)
• Creutzfeldt-Jakob disease (CJD)
• Scrapie
• Bovine Spongiform Encephalopathy (BSE)
• Chronic Wasting Disease (CWD)
Prion DiseasesPrion Diseases
HumanHuman AnimalAnimal
![Page 4: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/4.jpg)
Classification of prion diseasesClassification of prion diseases• Infectious/ExogenousInfectious/Exogenous
– e.g., Kuru, BSE (mad cow disease), Scrapie– Spread by
• Consumption of infected material.• Transfusion.
• SporadicSporadic
• Familial/HereditaryFamilial/Hereditary– Due to autosomal dominant mutation of PrP.
![Page 5: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/5.jpg)
Differences between cellular and scrapie proteinsDifferences between cellular and scrapie proteinsPrPPrPCC PrPPrPSCSC
SolubilitySoluble Non soluble
Structure Alpha-helical Beta-sheeted
Multimerisation state Monomeric Multimeric
InfectivityNon infectious Infectious
Susceptibility to Proteinase KSusceptible Resistant
![Page 6: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/6.jpg)
Steps in the biosynthesis of PrPSteps in the biosynthesis of PrPcc
![Page 7: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/7.jpg)
Post-translational processing of PrPPost-translational processing of PrP
S S
AC B
![Page 8: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/8.jpg)
ER Golgi
Endosome
Cellular trafficking and cleavage of PrPCellular trafficking and cleavage of PrP
![Page 9: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/9.jpg)
Mechanism of Internalization of PrPMechanism of Internalization of PrPCC
![Page 10: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/10.jpg)
Hypothetical model for a PrPHypothetical model for a PrPc c receptorreceptor
![Page 11: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/11.jpg)
Model for the function ofModel for the function of
LRP- LR as the receptor for PrPLRP- LR as the receptor for PrP
HSPG
Dependent binding domain
Direct binding domain (aa 161-179)
LRP/LR
PrP
BDI
(aa 144-179)
Heparan sulfate chain (HS)
Sulfated domains
HSPG
Proteoglycan moiety
GPI
BDII (aa 53-93)
![Page 12: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/12.jpg)
Cell Culture Systems for Prion PropagationCell Culture Systems for Prion Propagation
![Page 13: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/13.jpg)
Sequence of prion proteinSequence of prion protein
![Page 14: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/14.jpg)
PrPC + Cu (Copper)
Antioxidant activity
Resistance to oxidative stress
Prevent neuronal dysfunction
(Brown et al., 2002)
• AntioxidativeAntioxidativeFunctions of Prion proteinFunctions of Prion protein
• Other functionsOther functions
![Page 15: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/15.jpg)
Models for the conversion of PrPc to PrPsc
![Page 16: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/16.jpg)
Time taken for Transformation of mutant PrPTime taken for Transformation of mutant PrPc c to a PrPto a PrPScSc state state
Detergentinsoluble
PIPLC-resistant
Synthesis of Mutant PrPc
Protease-resistant
<10 min
BFA
180C
0.5-1 hr
1-6 hr
Endoplasmic Reticulum
Plasma membrane/
Endocytic Pathway
![Page 17: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/17.jpg)
Effect of conformation of PrP on Pro KEffect of conformation of PrP on Pro K
![Page 18: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/18.jpg)
Model of the cellular pathways Model of the cellular pathways involved in generation of PrPinvolved in generation of PrPScSc
![Page 19: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/19.jpg)
Proposed model of PrPProposed model of PrPcc
aggregation and induction of CtmPrPaggregation and induction of CtmPrP
![Page 20: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/20.jpg)
PathogenesisPathogenesis
![Page 21: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/21.jpg)
Mechanism of PrPMechanism of PrPscsc induced apoptosis induced apoptosis
![Page 22: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/22.jpg)
They generate a C-terminal fragment(C2) which has molecular
weight of 27-30 kDs.
Increase in intracellular levels of Calcium increase
production of terminal fragments .
Calpastatin prevents production of C2.
Inhibitors of lysosomal proteases has no effect on C2
production.
Telling et al.,2004
What are Calpains?What are Calpains?
![Page 23: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/23.jpg)
It was proposed that prion-associated toxicity involves altered
trafficking of PrPc.
Inhibition of ubiquitin-proteasome system(UPS).
Deposition of aggresomes of PrPSc in nerve cells.
Induction of Apoptosis with activation of Caspase 3 and
Caspase 8.
Complete molecular basis for neuronal death is not known.
Aggregates of over expressed PrPc does not cause cell death.
Tabrizi et al., 2005
Role of CaspasesRole of Caspases
![Page 24: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/24.jpg)
The AGAAAAGA Palindrome in Prion Generation
Factors Responsible for Prion PropagationFactors Responsible for Prion Propagation
Norstrom & Mastrianni, 2005
![Page 25: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/25.jpg)
Factors Responsible for Prion Propagation cont…
• PrPc association with lipid rafts in the early secretory pathway.
• Creutzfeldt–Jakob disease (CJD) in Libyan Jews, linked to the E200K mutation in PRNP (E200KCJD).
![Page 26: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/26.jpg)
E.g. Hsp70, GroEL
Model for chaperone-supervised PrP conversionModel for chaperone-supervised PrP conversion
![Page 27: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/27.jpg)
Phospholipase A2 Inhibitors prevent prion replication.
Platelet-activating Factor Antagonists also inhibits prion replication.
Bate et al.,2004
Drugs which share a N-benzylidene-benzohydrazide core structure.
Trimethylamine N-oxide (TMAO), can prevent formation of PrPSc.
Factors that prevent Prion ReplicationFactors that prevent Prion Replication
Bertsch et al.,2005
Bennion, 2004
![Page 28: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/28.jpg)
Gross and Microscopic Changes Gross and Microscopic Changes
Grossly there is Cortical atrophy and Grossly there is Cortical atrophy and ventricular ventricular dilatation dilatation
may also be present.may also be present.
Gross changes
![Page 29: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/29.jpg)
ScrapieScrapie BSEBSE
CJDCJDKuruKuru
Microscopic changes
![Page 30: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/30.jpg)
• Gliosis within plaques.
• Loss of oligodendrocytes within plaques.
• Axons usually remain intact in plaques.
• Both CD4+ and CD8+ lymphocytes are present in active
lesions.
(Kretzschmar et al.,1996, Wilesmith et al.,
1997).
Other microscopic changesOther microscopic changes
![Page 31: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/31.jpg)
Diagnosis can be made by:
1. Clinical signs and Symptoms.
2. Detection of Scrapie
Associated fibrils.
3. Detection of Abnormal Prion protein (PrPsc) by Western blotting.
4. Two dimensional Gel Electrophoresis. 5. Imunodiagnosis of Prion disease.
6. Bioassay in Mice.
Diagnosis Diagnosis
Scrapie Associated fibrils.
![Page 32: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/32.jpg)
PrPC
PrPSC
PrPC
Mechanism of plaque formationMechanism of plaque formation
![Page 33: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/33.jpg)
PrPsc fibrils
![Page 34: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/34.jpg)
Plaque
![Page 35: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/35.jpg)
Molecular hallmark of the disorder is the accumulation of abnormal prion protein(PrPSc).
Physiological functions of cellular prion protein (PrPc) is not clear.
Identity of intracellular compartment where PrPc to PrPSc occurs is not established.
Prion peptide of 106-126 residues is found to be neurotoxic.
Studies on prion protein will open the avenues for treatment of other neurodegenerative disorders.
ConclusionConclusion
![Page 36: 30511](https://reader035.vdocuments.net/reader035/viewer/2022062322/55cf914f550346f57b8c6fb2/html5/thumbnails/36.jpg)