This video we're going to begin our lesson on prions. And so first we need to recall from some of our previous lesson videos that the term prions is actually derived from proteinaceous 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 proteinaceous infectious agents, like viruses and viroids, are also acellular obligate intracellular parasites. However, unlike viruses, which are made of proteins, nucleic acids, and sometimes lipids, and viroids, which are only made of RNA, prions, as their name implies with the proteinaceous 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-Jakob disease, family fatal insomnia, and kuru, 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 tissue 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 micrograph 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 has these spongiform lesions, basically these holes, and, it is deteriorating. And all of these holes, these gaps that you see here, this is what gives the brain a sponge-like appearance, which is where it gets its name, spongiform encephalopathies. And so, 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 here concludes our brief introduction to prions, 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.
Prions - Online Tutor, Practice Problems & Exam Prep
Prions
Video transcript
Prion Development in Neurons Leads to Scrapie
Video transcript
This video, we're going to be talking about the prion development in neurons leading to the disease scrapie in animals. And so the infectious prion protein that is misfolded leading to the disease scrapie is PrPSc, which is really just an abbreviation for prion protein scrapie. And the normal form of that prion is actually PrPC, which is prion protein cellular, and so PrPC is the normal protein with normal function, and PrPSc is the prion that leads to the disease scrapie. And so the accumulation of the PrPSc, the prion form, in the brain is attributed to its interaction with the normal protein, which is once again PrPC. And so the interaction PrPC. And so the interaction between PrPSc, the prion, and the normal protein, PrPC, is going to cause the normal protein, PrPC, to misfold. And if the PrPC protein misfolds, it is going to result in a PrPSc prion. And so the PrPSc prion will accumulate over time through interacting with PrPC and converting the PrPC to PrPSc. And so, PrPSc 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 prion development in 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 can be, PrPC, which is the normal functioning protein with the correct shape, but if there is a prion, it will be PrPSc. And so if they're both present in a neuron cell, what can happen is the PrPSc can interact with the PrPC. And so the misfolded PrPSc prion protein can interact with the normal PrPC protein. And so the misfolded PrPSc prion can convert the normal PrPC into PrPSc. And so notice that the PrPSc is accumulating, and so it can continue to interact with other normal PrPC proteins and the continued conversion as PrPC PrPSc accumulates. And so the accumulation of PrPSc is going to lead to the aggregation or PrPSc aggregation, or clumping as you see like that and ultimately that clumping can lead to causing spongiform lesions 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.
What are prions?
Which of the following is true of prions?
Viroids and prions are both infectious agents. All of the following are major differences between viroids and prions except which of these answers?
Mad cow disease is a prion disease found in cattle. Why are prion diseases in meat a big concern?
