A number of brain diseases caused by mutant prion proteins, such as mad cow disease or scrapie in sheep, might be averted if normal prion proteins can be depleted.
A number of brain diseases caused by mutant prion proteins, such as mad cow disease or scrapie in sheep, might be averted if normal prion proteins can be depleted, researchers report.
Prion disease, which includes the human form of mad cow disease called variant Creutzfeldt-Jakob disease, is thought to be caused when prion protein in the brain becomes misfolded, and this causes normal prion protein to follow suit. The accumulation of mutant prions is toxic to brain cells, eventually turning the brain to mush.Now UK researchers report that in mice that have been infected with disease-related prions, early depletion of naturally occurring normal prion protein in neurons leads to repair of sponge-like brain damage.
Their mouse experiments showed that cognitive and behavioral deficits and impaired nerve function accompany early brain damage. "Remarkably, these behavioral and synaptic impairments recover when (normal prion protein) is depleted, in parallel with reversal of spongiosis," the team reports.
"These data now lead to the hope that early intervention in human prion disease will not only halt clinical progression but allow reversal of early behavioral and cognitive abnormalities," Dr. Giovanna R. Mallucci from the Institute of Neurology in London and colleagues write in the journal Neuron.
"Currently, no treatment can prevent the cognitive and motor deficits associated with widespread neurodegeneration in prion disease," they point out.
Mallucci and colleagues do point out that the idea of eliminating normal prion protein "remains somewhat controversial…as the physiological role of the native protein is still unclear." They note, however, that normal prion depletion itself had no effect on behavior and cognition in uninfected animals in the current study.
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