Prions

in this video we're going to begin our lesson on pry ins. And so first we need to recall from some of our previous lesson videos that the term prions is actually derived from pro tenacious infectious agents. And so you can see the P. R. The I. N. And so those are also found here in prions. And so these prions or pro tenacious infectious agents like viruses and viral loads are also a cellular obligate intracellular parasites. However unlike viruses which are made of proteins, nucleic acids and sometimes lipids and vier oils which are only made of RNA Pry INS as their name implies with the pro tenacious part are only made of misfolded proteins. Now these prions can actually cause normal proteins to misfold which can ultimately lead to some type of neurodegenerative disease. And so notice down below over here on the left hand side of our image we're showing you some prion diseases or diseases caused by prions in humans such as Creutzfeldt Jacob disease, family, fatal insomnia and kourou and then also some prion diseases that cause disease in animals such as scrapie mad cow syndrome and chronic wasting disease. Now these prions can ultimately accumulate in neural tissues such as for example the brain and they can cause what are known as transmissible spongiform encephalopathies. And so these transmissible spongiform encephalopathies are really when brain tissue deteriorates forming holes and a sponge like appearance in the brain. And so if we take a look at our image down below. Notice on the left hand side over here what we're showing you is a micro graph of a normal brain of normal brain cells. And on the right over here, what we're showing you is a brain with spongiform encephalopathies. And so what you'll notice is the brain with spongiform encephalopathies have these spongiform legions, basically these holes and it is deteriorating and all of these holes, these gaps that you see here. Uh this is what gives the brain a sponge like appearance, which is where it gets its name. Spongiform encephalopathies. And so, um ultimately again, these are going to be associated with prion formation and can lead to these degenerative diseases that we have here. And so this year concludes our brief introduction to pry ins and we'll be able to talk a little bit more about prions as we move forward in our course. And so I'll see you all in our next video

in this video, we're going to be talking about the pre on development and neurons leading to the disease scrapie in animals. And so the infectious prion protein that is misfolded leading to the disease scrapie is pRP sc which is really just an abbreviation for prion protein scrapie. And the normal form of that prion is actually PRP C. Which is prion protein cellular. And so PRP C. Is the normal protein with normal function. And PRP sc is the pry on that leads to the disease scrapie. And so the accumulation of the prp sc. The pry on form in the brain is attributed to its interaction with the normal protein which is once again P. R. P. C. And so the interaction between Prp sc, the prion and the normal protein PRP C. Is going to cause the normal protein PRP C. To misfold. And if the PRP C protein misfolds it is going to result in a prp sc prion. And so the prp sc prion will accumulate over time through interacting with PRP. C. And converting the PRP C. Two PRP sc. And so PRP sc accumulates and begins to aggregate in the brain, leading to spongiform encephalitis and the disease scrapie in animals. And so if we take a look at our image down below, we can get a better understanding of the pre in development and neuron cells and how that results in the neurological disease scrapie in animals. And so notice on the far left over here, we're taking a look inside of a neuron which is a type of cell of the nervous system a cell that can be found in the brain. And so inside the neuron there uh can be PRP C. Which is the normal functioning protein with the correct shape. But if there is a pry on it will be PRP sc. And so if they're both present and a neuron cell, what can happen is the pRP sc can interact with the PRP. C. And so the misfolded pRP sc prion protein can interact with the normal PRP. C. Protein. And so the misfolded prp sc prion can convert the normal PRP. C into PRP sc. And so notice that the pRP sc is accumulating and so it can continue to interact with other normal PRP. C proteins and the continued conversion as P. R. P. C. P. R PSC accumulates. And so the accumulation of PRP sc is going to lead to the aggregation or prp sc aggregation or clumping as you see like that. And ultimately that clumping can lead to causing spongiform legions which are those holes that you can find in brain tissue. And that leads to the disease scrapie in animals. And so really these prions once again are just misfolded proteins that can interact with normal proteins and cause the normal proteins to also misfold and become prions. And so this here concludes our brief lesson on prion development and neurons leading to the disease scrapie. And we'll be able to get some practice applying these concepts as we move forward in our course. And so I'll see you all in our next video.