"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."
Re:Aren't prions also responsbile for disease? (Score:3, Insightful)
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 genetics, so Mad Cow Disease and other transmissible spongiform encephalopathies such as CJS are ultimately self-limiting.
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. The immune system looks for markers to know what belongs and what doesn't, so it's probable that MS is normally caused by damage to the genes that are responsible for the creation of these markers in the first place.
It is conceivable that a mutant or misfolded protein could actively damage the markers, but the likelihood of this being a major cause is pretty small, simply because, from what we know, there are so many things that are more likely to go wrong.
Re:prion proteins != prions (Score:3, Insightful)
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.
Re:Aren't prions also responsbile for disease? (Score:2, Insightful)
Re:Prions (Score:2, Insightful)
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.