Alzheimer's disease & dementia

Alzheimer's disease is a 'double-prion disorder,' study shows

Two proteins central to the pathology of Alzheimer's disease act as prions—misshapen proteins that spread through tissue like an infection by forcing normal proteins to adopt the same misfolded shape—according to new ...

Neuroscience

Retinal prion disease study redefines role for brain cells

National Institutes of Health scientists studying the progression of inherited and infectious eye diseases that can cause blindness have found that microglia, a type of nervous system cell suspected to cause retinal damage, ...

Diseases, Conditions, Syndromes

New skin test detects prion infection before symptoms appear

Prions can infect both humans and animals, causing Creutzfeldt-Jakob disease (CJD) in humans, mad cow disease in cattle, and chronic wasting disease in elk and deer. The infectious, misfolded protein particles often go undetected ...

Alzheimer's disease & dementia

New compound shows promise in treatment of Alzheimer's

Yale researchers have identified a drinkable cocktail of designer molecules that interferes with a crucial first step of Alzheimer's and even restores memories in mice, they report Jan. 2 in the journal Cell Reports.

Alzheimer's disease & dementia

Test detects protein associated with Alzheimer's and CTE

An ultrasensitive test has been developed that detects a corrupted protein associated with Alzheimer's disease and chronic traumatic encephalopathy (CTE), a condition found in athletes, military veterans, and others with ...

Neuroscience

How prions invade the brain

The spread of prions to the brain does not occur by direct transmission across the blood-brain barrier, according to a study published November 29 in the open-access journal PLOS Pathogens by Annika Keller and Adriano Aguzzi ...

Diseases, Conditions, Syndromes

Not all prion strains interfere with each other

The first example of prion strains that replicate independently in vitro and in vivo suggests that strain diversity may be greater than previously thought, according to a study published October 18 in the open-access journal ...

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Prion

A prion (pronounced /ˈpriː.ɒn/ ( listen)) is an infectious agent that is composed of protein. To date, all such agents that have been discovered propagate by transmitting a mis-folded protein state; the protein does not itself self-replicate and the process is dependent on the presence of the polypeptide in the host organism. The mis-folded form of the prion protein has been implicated in a number of diseases in a variety of mammals, including bovine spongiform encephalopathy (BSE, also known as "mad cow disease") in cattle and Creutzfeldt-Jakob disease (CJD) in humans. All known prion diseases affect the structure of the brain or other neural tissue, and all are currently untreatable and are always fatal. In general usage, prion refers to the theoretical unit of infection. In scientific notation, PrPC refers to the endogenous form of prion protein (PrP), which is found in a multitude of tissues, while PrPSC refers to the misfolded form of PrP, that is responsible for the formation of amyloid plaques that lead to neurodegeneration.

Prions are hypothesized to infect and propagate by refolding abnormally into a structure which is able to convert normal molecules of the protein into the abnormally structured form. All known prions induce the formation of an amyloid fold, in which the protein polymerises into an aggregate consisting of tightly packed beta sheets. This altered structure is extremely stable and accumulates in infected tissue, causing tissue damage and cell death. This stability means that prions are resistant to denaturation by chemical and physical agents, making disposal and containment of these particles difficult.

Proteins showing prion-type behavior are also found in some fungi and this has been important in helping to understand mammalian prions. However, fungal prions do not appear to cause disease in their hosts and may even confer an evolutionary advantage through a form of protein-based inheritance.

The word prion is a compound word derived from the initial letters of the words proteinaceous and infectious, with -on added by analogy to the word virion.

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