"Normal" Prions May Protect Myelin

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."

Comments

Prions

[girlintraining]

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.

Re:Prions

[khayman80]

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.

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.

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.

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.