talking about PrNp gene and prion disease .

1. Prion Protein
Bahaaddin Ahmed Saber
27-05-2015

2. OUT LINE
Definition
Gene Expression of Prion protein
Function of protein
Diagnosis
Disease affect by prion protein
Treatment
And Prevention

3. Definition of Prion
Prion: A small proteinaceous infectious disease-causing agent that is believed
to be the smallest infectious particle. A prion is neither bacterial nor
fungal nor viral and contains no genetic material. Prions have been held
responsible for a number of degenerative brain diseases, including
Mad cow disease,
Creutzfeldt-Jakob disease,
fatal familial insomnia ,kuru, and an unusual form of
hereditary dementia known as Gertsmann-Straeussler-Scheinker disease.

4. PRNP gene
The PRNP gene is located on the short (p) arm
of Chromosome 20 at position 13.
More precisely, the PRNP gene is located from base
pair 4,686,150 to base pair 4,701,587 on
chromosome 20.

7. What is chromosome 20?
Humans normally have 46 chromosomes in each cell, divided
into 23 pairs. Two copies of chromosome 20, one copy
inherited from each parent, form one of the pairs.
Chromosome 20 spans about 63 million DNA building
blocks (base pairs) and represents approximately 2 percent
of the total DNA in cells.
Identifying genes on each chromosome is an active area of
genetic research. Because researchers use different
approaches to predict the number of genes on each
chromosome, the estimated number of genes varies.
Chromosome 20 likely contains 500 to 600 genes that
provide instructions for making proteins. These proteins
perform a variety of different roles in the body.

8. Function of Prion protein
• The PRNP gene provides instructions for making a protein
called prion protein (PrP), which is active in the brain and
several other tissues. Although the precise function of this
protein is unknown, researchers have proposed roles in
several important processes. These include the transport of
copper into cells and protection of brain cells (neurons)
from injury (neuroprotection). Studies have also suggested
a role for PrP in the formation of synapses, which are the
junctions between nerve cells (neurons) where cell-to-cell
communication occurs.
• Different forms of PrP have been identified. The normal
version is often designated PrPC to distinguish it from
abnormal forms of the protein, which are generally
designated PrPSc.

9. What other names do people use for the PRNP gene
or gene products?
AltPrP … ASCR… CD230 antigen……CJD
GSS…. MGC26679… PRIO_HUMAN
prion protein (p27-30) (Creutzfeldt-Jakob disease, Gerstmann-Strausler-Scheinker
syndrome, fatal familial insomnia)
PRIP…PrP
PrP27-30
PrP33-35C
PrPc
PrPSc

10. Disease Relation with Prion Protein
- Creutzfeldt-Jacob disease (CJD) and variant CJD in
humans

11. Disease Relation with Prion Protein
Scrapie ( In Sheep).

12. Disease Relation with Prion Protein
Cow Mad disease :

13. Models of PrPC to PrPSc conversion. (A) The heterodimer model proposes that upon infection of an appropriate host cell,
the incoming PrPSc (orange) starts a catalytic cascade using PrPC (blue) or a partially unfolded intermediate arising
from stochastic fluctuations in PrPC conformations as a substrate, converting it by a conformational change into a new
β-sheet–rich protein. The newly formed PrPSc (green-orange) will in turn convert new PrPC molecules. (B) The
noncatalytic nucleated polymerization model proposes that the conformational change of PrPC into PrPSc is
thermodynamically controlled: the conversion of PrPC to PrPSc is a reversible process but at equilibrium strongly favors
the conformation of PrPC. Converted PrPSc is established only when it adds onto a fibril-like seed or aggregate of
PrPSc. Once a seed is presModels of PrPC to PrPSc conversion. (A) The heterodimer model proposes that upon infection
of an appropriate host cell, the incoming PrPSc (orange) starts a catalytic cascade using PrPC (blue) or a partially
unfolded intermediate arising from stochastic fluctuations in PrPC conformations as a substrate, converting it by a
conformational change into a new β-sheet–rich protein. The newly formed PrPSc (green-orange) will in turn convert
new PrPC molecules. (B) The noncatalytic nucleated polymerization model proposes that the conformational change of
PrPC into PrPSc is thermodynamically controlled: the conversion of PrPC to PrPSc is a reversible process but at
equilibrium strongly favors the conformation of PrPC. Converted PrPSc is established only when it adds onto a fibril-like
seed or aggregate of PrPSc. Once a seed is present, further monomer addition is acceleratedent, further monomer
addition is accelerated.
.

14. Diagnosis
• MRI scans of the brain
• Samples of fluid from the spinal cord (spinal
tap)
• Electroencephalogram, which analyzes brain
waves; this painless test requires placing
electrodes on the scalp
• Blood tests
• Neurologic and visual examinations to
evaluate for nerve damage and vision loss

15. Diagnosis
DIAGNOSING TSEs
It can be very difficult to test for PrPSc because it may be present in small amounts and separating it out from
PrPC is not trivial. The methods currently being used test dead animal tissue. There are proposed ways to test
live animals, such as detecting Prions in blood, urine or Cerebrospinal Fluid (CSI), but these methods are not
yet in widespread use. More information about the differences between the conformations of the proteins is
needed before these other tests can become a reality.
1Bioassay
The most conclusive form of testing is the bioassay. This test works by taking a tissue sample of a suspected
infected animal and putting it into a mouse or other animal and waiting for the disease to develop in the model
organism. Obviously, this is a very slow and labor-intensive method of testing for the disease. A faster form of
testing, but still labor intensive, is Immunohestochemistry. In this method, antibodies that recognize PrPSc are
injected into brain tissue, and then observed on slides under a microscope for the presence of these antibodies
. If the antibodies are present, then they have attached to infectious prions and the tissue is infectious. Because
each slide must be examined under a microscope, this type of test can take time and energy that makes it hard
for mass testing.
2Immunoassay
Another type of test, the immunoassay, is fast and easier to complete, but only applicable when there are high
levels of infectious prions; subsequently, lower levels may go undetected. The Immunoassay works by first
adding Protease to brain tissue, which will break down all the non-infectious form of prions and leave only
infectious prions. Then, antibodies sensitive to prions are added to the solution. The antibodies used are
tagged with a visual marker so that the presence of the prions with show up. Testers can also run the solution
on a Gel and the presence bands will mean that there is infectious prion protein. The reason this only works for
high levels of infectious protein is that although many PrPScs are resistant to breakdown by proteases, many
are not, especially in the early stages of the disease (it is not known why this is the case). Therefore, after
proteases have been applied to the mixture, all of the PrPC is broken down, and some of the PrPSc is broken
down as well, so only a little bit remains. Furthermore, it is hard to find antibodies that will only bind to the
infectious form when we do not know the exact conformation differences, so proteases are a necessary step
before adding antibodies.

16. Diagnosis
Conformation-Dependent Immunoassay
3- Conformation dependent Immunoassay (CDI)Finally, a newer
method that is both quick and accurate for low levels of infectious
protein. CDI uses tissue taken from a live animal mixed with a
chemical that separates infectious from non-infections prions based
on their conformations. Next, an antibody tagged with flourescence is
added to the separated area, and if the tissue same contains
infectious protein, the antibody will fluoresce .
4- Brain Imaging
is another diagnostic tool that can be used for humans, but is not
applicable to diagnosing animals that may be fed to humans.
Furthermore, brain scans are expensive, and would probably only be
used if someone is showing symptoms of aTSE, which often means
the disease is very advanced. The development of a wider diagnostic
test that could be applied to anyone who might be at risk of a TSE
would be incredibly valuable because it might be easier to slow down
in an early stage of the disease (Committee on Transmissible
Spongiform Encephalopathies, 2004).

17. 5- Protein Misfolding Cyclic Amplification (PMCA)
One of the obstacles to creating a test that does not require brain tissue, as all of the
above tests do, is the low level of prions in other tissues. Formulating a blood or
urine test would require a means of amplifying the infectious protein to levels that
are detectable. This is difficult because since it is only protein, polymerase chain
reaction (a very efficient method for amplifying nucleic acids) is not applicable.
However, there is a method being developed that may allow an amplification
process that would make a blood test more feasible. This amplification process is
called Protein Misfolding Cyclic Amplification (PMCA). It has been shown to work
experimentally by mixing infected prions with normal prions. The idea behind it is
that infectious prions transform normal prions into infectious prions, so the normal
prions are there for the infectious to work on changing. However, often the
infectious prions form clumps, so they less actively change the normal prion
conformations. Therefore, this method uses sonication-pulses of sound waves-to
break up infectious prion clumps so that they will spread throughout the tissue mix
and transform the normal prions. This seems to work as a method of amplifying
infectious protein. Another possible way to get around the low levels of infectious
protein is to detect a "surrogate marker" instead of the protein itself. There may be
other proteins or molecules that indicate the presence of the infectious prion
protein that are easier to detect, and could therefore act as a "surrogate marker"
because they, instead of prions, could be tested for in tissue. Another obstacle is
how to distinguish among the different strains of TSEs. Knowing this could be
integral to determining the source of the disease (inherited, spontaneous,
transmitted) and to inventing with more targeted ways of dealing with the different
strains disease (Committee on Transmissible Spongiform Encephalopathies, 2004).

18. protein misfolding cyclic amplification machine

20. Symptoms of Prion disease
• Rapidly developing dementia
• Difficulty walking and changes in gait
• Hallucinations
• Muscle stiffness
• Confusion
• Fatigue
• Difficulty speaking

21. Treatment
• Prion diseases can't be cured, but certain
medications may help slow their progress. Medical
management focuses on keeping people with these
diseases as safe and comfortable as possible despite
progressive and debilitating symptoms.
1- Quinacrine
2-Pentosan polysuphate (PPS)
3-Tetracyclic Compounds
4-Flupirtine
5-Potential Treatments (Immunotherapy)

22. Thanks for your Attention