"Normal" Prions May Protect Myelin 81
thomst writes "Nature Neuroscience just published an online article about the function of 'normal' prions in protecting myelin, the substance that sheathes and protects sensory and motor nerves. The international study (which has 11 authors) concluded that 'normal' (i.e., not mis-folded) prions may form a protective coat around myelin. The researchers found that Prnp -/- mice (mice with the gene for prions knocked out) consistently developed progressive demyelination, inevitably leading to persistent polyneuropathy by 60 weeks of age. Their data suggest that damage to myelin sheaths cause normal prions to cleave, and the resulting prion fragments activate Schwann cells, which are known to play a part in myelin repair. This research might eventually lead to possible treatments for progressive polyneuropathies in humans, including those mediated by Creutzfeldt-Jakob disease, multiple sclerosis, Alzheimer's, and even diabetes."
Oops... (Score:4, Interesting)
I kept reading "Prisons" instead of Prions and was dumbfounded beyond belief.
I looked away from my screen for a minute imagining the possibilities. Then I looked back, noticed my mistake, and felt like an idiot.
And thats why I'm posting; I'd like to share my idiocy with you.
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And thats why I'm posting; I'd like to share my idiocy with you.
No worries my good man! This is slashdot. You are in good company.
Idiocy (Score:3, Funny)
I was thinking of a response more like:
We're all full up of idiocy here. Why don't you try next door?
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I did the same thing. I started reading the summary and got to the part about the mice and said to myself, "What are the mice doing in prison?" Doh!
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I was anticipating a myelin's law, kind of like megan's law, since prions arent doing a good job protecting the public.
Re:Oops... (Score:5, Funny)
I kept reading "Prisons" instead of Prions and was dumbfounded beyond belief.
I looked away from my screen for a minute imagining the possibilities. Then I looked back, noticed my mistake, and felt like an idiot.
And thats why I'm posting; I'd like to share my idiocy with you.
And I'm thinking "I know hybrid cars are supposed to be good for the environment but aren't they overselling it a bit much? And who makes the Prion anyway, is that Dodge or Toyota?"
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I kept reading "Prisons" instead of Prions and was dumbfounded beyond belief.
News at 10: D&D harmful to Myelin [slashdot.org].
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He misread it as "prisons" not "psions" ...
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And thats why I'm posting; I'd like to share my idiocy with you.
That's the net's primary function! Thanks for doing your part :-)
Not as bad as thinking... (Score:4, Funny)
"You must construct additional prions!"
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"You must construct additional prions!"
"you require more minerals"
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And thats why I'm posting; I'd like to share my idiocy with you.
I had that problem before I went to prison. Figured out it had something to do with my elin.
It was probably my puns that sent me to prison in the first place.
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You're not too off the mark there, Freud. Speaking as someone enjoying demyelination on two fronts (blindness, neuropathy, separate reasons) it is a bit of a prison.
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Any treatment options are good (Score:2)
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Aren't prions also responsbile for disease? (Score:2, Interesting)
So, this seems to indicate that some other disease causes malfunctioning prions, which result in a new disease such as CJS.
Does that mean something like a family history of MS for instance, which results partially from myelin damage, is an indicator for CJS?
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No, I meant "creutzfeldt jakob syndrome" which is a perfectly acceptable name for the disorder.
Please stop trying to correct things if you don't know what you're talking about.
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Google and Wikipedia tell me that you're wrong, not him. You shouldn't criticize people when it's going to make you look like the dumbass.
Creutzfeldt–Jakob disease [wikipedia.org]
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A prion is a protein that modifies other proteins to take on its shape, creating a chain reaction that converts all/most of the normal form into the prion form. Usually, the prion is a malformed protein that has an important function in its normal role. Malformed proteins are not at all uncommon (in fact a significant portion of cellular activity results in mistakes!) but ones that are contagious in this way can persist if they get transferred to other organisms. Generally this involves cannibalism or genet
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MS may be different in some people:
http://www.cbc.ca/health/story/2009/11/23/multiple-sclerosis-zamboni-ccsvi.html [www.cbc.ca]
--jeffk++
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No, I'm sorry, you can't just claim this (Score:2, Interesting)
"However, prions are not, in principle, limited to myelin, and there are a lot of things that can go wrong in myelin sheaths. Your example, multiple sclerosis, actually results from the immune system attacking myelin, which is an unrelated problem."
How do you know this? According to the article, they may very well be related, for example, when the immune system attacks the myelin, the byproduct of the breakdown could be malfunctioning prions.
I don't see anything that proves in any way that they're "unrelat
Prions (Score:4, Informative)
The problem with prions, as I understand it, is that they can't be targeted by the autoimmune system because they can't be bonded to; And that is because of the blood-brain barrier. Normal prions are folded proteins that self-terminate. That is, they end after a certain number of repeats. But abnormal ones don't ever stop growing -- and they occasionally break apart, but they keep folding forever. It's like trash that never biodegrades, in your body, clogging up the space between nerve endings until nothing gets through. That's not a technically accurate description, but it's a good way to view the problem.
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Re:Prions (Score:4, Funny)
I think I understand, but I also think a car analogy is in order.
Fine. *mutter, mutter* Your car is just a metaphor for a folding protein called a prion. Except your car isn't a car, but a robot. We'll call it a transformer. Now there are good transformers, and Decepti--I mean, bad robots. The bad robots are bad because they just don't know when to stop. And they want to take over everything using a device called the AllSpark. The AllSpark is the source of ultimate power for the robots good and bad. Except the AllSpark is really nucleic acid. The only way to beat the Deceptic--I mean, bad prions, is to destroy the AllSp--er, nucleic acid. But that would be bad, because without the nucleic acid, none of the cars would run, nobody would get anywhere, and then anarchy would result and the world would end.
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I think I love you in a platonic sort of way.
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I think I love you in a platonic sort of way.
Well, as long as it stays platonic I won't send you the way of Socrates.
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You do know what his last words were, right?
"I drank WHAT?" : Socrates
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"I drank WHAT?" : Socrates
Actually, he mentioned his cock. ;)
Re:Prions (Score:5, Informative)
Prions are dangerous mainly because proteins are more stable than nucleic acids, so sterilization techniques that are adequate against viruses and bacteria aren't effective against prion-based diseases like BSE and CJD.
Prions are proteins that have mis-folded. They stop folding on the same microsecond timescale as normal proteins, but most develop "amyloid folds" that (as you say) causes them to build up like trash in the body.
Prions certainly stop growing. Also, a big problem is that they form structures that are very stable. You seem to be describing cancer, which is effectively immortal, lacks the usual constraints on mitosis frequency, and breaks apart (metastasizes) to spread throughout the body.
A prion's actual method of infection is that the mis-folded protein induces other correctly-folded proteins in its vicinity to change to the mis-folded state.
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Thank you for being awesome, khayman80. ^_^
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I try. ;)
For what it's worth, your post should be modded interesting at the very least, if only to annoy that AC stalker you seem to have acquired.
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Prions are dangerous mainly because proteins are more stable than nucleic acids, so sterilization techniques that are adequate against viruses and bacteria aren't effective against prion-based diseases like BSE and CJD.
Minor correction: Proteins, in general aren't particularly stable. Some are, but others aren't. Your DNA, depending on the G-C content, will melt at ~140 F, whereas a bad fever will start to denature proteins at ~108 F. Even PrP-C (Prion Protein - normal, endogenous form) isn't particularly stable. The PrP-SC (disease form, e.g. Scrapie, Mad Cow, or CJD) converts some of PrP-C's alpha helices into more compacted beta-pleated sheets, which make the protein very resistant to heat and the body's natural pr
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they can't be targeted by the autoimmune system because they can't be bonded to; And that is because of the blood-brain barrier
I'd also guess without doing any reading on the subject that being inside the cell further prevents this. If a virus is inside a cell, that will ideally (for the cell) trigger cell suicide. If that doesn't happen or the virus blocks it. Some (most?) cells move bits of protiens out to their surface after they've digested them as part of normal cell function. If a bit of a viral protein does this, immune cells can recognize it and tell the cell to kill itself or can signal other cells to kill the infected
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Why was this modded informative? It's all absolutely wrong.
What causes abnormal prions? (Score:1)
Are there any extrernal factors that contribute to abnormal prions, such as pollutants, carcenogens, genes, etc?
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http://tolweb.org/Priapulida/2476
Yes, they're called priapulidae [tolweb.org].
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Re:I read the summary and didn't understand any of (Score:3, Informative)
The first rule of Protect Myelin... (Score:2)
...is you don't talk about Protect Myelin.
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Not all prions are bad [sciencenews.org]. Yeast for example have several prions that serve essential functions in the cell. The problem with human prions is that they are defective, they form plaques and damage cells while converting healthy proteins to defective ones.
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The sticking point here is that prion is defined as an infectious agent. Saying "normal prion" or "non-infectious prion" is like saying "non-explosive bomb". The adjective contradicts the nouns definition. What they're actually referring to are proteins (like PrP) which are the precursor to a prion (they can change into one). Apparently those proteins have some other uses too, which makes sense seeing as how evolution has a tendency to discard things that aren't in use.
Summary, headline misleading (Score:5, Interesting)
First, some background. Most people won't know what a prion is, so I'll explain with a bit of a computer analogy.
Most proteins are like binaries, being executed by the universe. If you put another molecule next to it (usually called a 'substrate') then it will do things to that molecule, by changing its shape and moving its charge around. Enzymes are proteins that return to their original shape afterward. There are also some relatively inert proteins that don't change shape or do anything; they're just for structural purposes.
The mechanics of the cell are very flaky, however. In a computer, we can be sure that when we copy a program from disk (DNA) into memory (polypeptides, an actual molecule) and run it, we'll get an exact copy. In molecular biology, though, all of these processes are imperfect: sometimes we copy the wrong data into the data bus (transcription errors), sometimes we write the wrong thing into RAM (translation errors), and sometimes, since these are 3D structures that need to fold into a proper shape to work, we actually rearrange the bytes that get loaded into memory (there are lots of bits that say 'insert tab A into slot B', but they work off electrical charges). This is called misfolding, reasonably enough. Most of the time the cell can recognise a malformed protein and marks it for deletion with a molecule called ubiquitin. (It then gets sent to the bit bucket.) To make matters worse, proteins can get old and misfold on their own (this usually calls for another round of ubiquitin if the protein doesn't break down totally)
A prion is a very specific class of misfolded protein, which appears sufficiently normal to the cell that it can't decompose it, lives in the brain where the body's immune system can't obliterate it, and, most importantly, if it collides with other proteins of what it was supposed to look like, it will turn them into prions as well, somewhat like vampires, zombies, or your classic EXE-modifying computer virus. The effect is that the prion spreads exponentially, screwing up the machinery of the cell.
Now, a protein has to be really complex for this to be possible. Some proteins are really simple, like the humble microtubule, which just provides a conduit, and some are incredibly complex, like DNA polymerase, which reads the nucleotides on DNA and makes a duplicate. These proteins are usually highly conserved (that is, they look very similar in many species, because if they break, the organism dies, and evolution hits a dead end), and very, very important. As a result, when a prion forms, it comes at a great cost to the overall health of the organism. Worse, it's transmissible (though usually only by cannibalism, which is kind of funny in a scary sort of way.)
So, after all that, what am I complaining about? Well, the headline makes it sound like we've discovered a case of stable self-modifying code, but we haven't. The article just talks about a protein, PrP^C, which is known to cause a prion problem when broken. It's named "axonal prion protein" because, until this study was conducted, that's all we knew about it: if it broke, it was bad. Similarly, there are a bunch of genes called "oncogenes" because they cause cancer if they break, but they're actually really important; removing them generally prevents cell division completely. There is no such thing as a "normal" prion, at least not one introduced by this article. It just turns into a prion if it breaks.
But hey, I'm only an undergrad; what do I know?
Re:Summary, headline misleading (Score:4, Informative)
The immune system can obliterate things in the brain--meningitis being the obvious example. In fact, there are some experimental tests being done that use the immune system to kill cancer cells in the brain. The immune system just doesn't have a mechanism for dealing with prions, and there's some possibility that it may be complicit in spreading the problem. And there have been some partially successful immunotherapy experiments on prions in mice, too.
Otherwise, yes, that's pretty close.
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Depends on how narrowly you define the immune system. There are microglial cells [wikipedia.org] that operate within the brain and spinal cord that behave like macrophages, except that they are in the brain and spinal cord. Presumably any immunotherapy would be training those cells, not mucking with T cells or B cells. I'm just guessing, though. Or they might be triggering inflammation sufficient to allow other immune cells through. Not sure.
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Worse, it's transmissible (though usually only by cannibalism, which is kind of funny in a scary sort of way.)
I think it's hilarious in my black-humor way.
It turns out you really can eat the brain of your enemy to gain their power... but only if their "power" was a debilitating brain disease!
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Brilliant. Yours is probably the clearest explanation of a prion I have read. I was confused on some of the points and this clears it up for me. Thanks once again!
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Damn! Why did you post this as AC? I wanted to befriend you because of that comment!
Basic Prion Biology (Score:1)
Ok, lots of partially correct information in the above posts
First, start with Wikipedia [wikipedia.org]. A prion is a self-replicating protein. It represents a misfolded form of a protein normally produced by the host organism. This misfolded form has the capability to 'template' its normally folded protein cousins into prions; this appears to happen when a prion binds /aggregates to the normal form, inducing a stable conformational change of the normal form to the prion state. Prions do not have to be in the brain, but th