PrPc: The Normal Prion

Abstract

PrPc is a normal cell‐surface glycoprotein that is conformationally characterized by two alpha helices and two complex‐type N‐linked oligosaccharide chains. This protein is unique in its propensity to misfold into a neurodegenerative disease‐causing proteinaceous infectious particle, known as a prion. PrPc can undergo conversion into PrPSc through spontaneous misfolding, a genetic mutation of the human PRNP gene, or exposure to a prion from an external source. When this happens, its composition shifts from an alpha‐helical, soluble protein low in beta pleated sheets to an insoluble, protease‐resistant particle with a high percentage of beta sheets. This resulting misfolded form, known formally as PrPSc, is pathogenic and aggregates in neural tissue by recruiting and converting more PrPc to PrPSc, ultimately causing neuronal cell dysfunction followed by cell death. The prion's form of “self‐replication” without utilizing genetic material is particularly fascinating, as it appears to defy the central dogma of biology and differs from all other pathogenic particle infection mechanisms. It is notable that some prions have evolved to act as transmissible infectious agents, similar to viruses, despite the absence of genetic material. This distinguishes some prion diseases, such as chronic wasting disease (CWD) and scrapie, from their inherited disease counterparts. The biosynthesis pathway of PrPc is similar to other cellular proteins, with replication occurring on the ribosomes on the endoplasmic reticulum. However, whereas malfunctioning proteins are normally tagged by ubiquitin and then degraded in a proteasome, the ubiquitin‐proteasome complex is inhibited during prion formation, allowing PrPSc to form and survive degradation, leading to its buildup in cytosol and subsequent neurotoxicity. Human and animal prion diseases have been classified into three broad categories‐‐genetic, sporadic, and acquired‐‐based on properties of the PrP proteins and prion infection morphology. Physical symptoms of prion infection include deviant behavior, dementia, ataxia, insomnia, paraplegia, and paresthesias. Commonly discussed prion‐induced diseases (differentiated via host type and slight conformational discrepancies between misfolded proteins) include scrapie, kuru, CJD, bovine spongiform encephalopathy (mad cow disease), and CWD. Here, we present current research on prions, with a focus on CWD, which was first found in Colorado and affects deer and other cervids.The Olathe North High School Team 1 MSOE Center for BioMolecular Modeling SMART Team used 3‐D modeling and printing technology to examine the structure‐function relationships and histology of PrPc, or the normal cellular prion.Support or Funding InformationThis project is a joint venture between the Milwaukee School of Engineering and the Medical Professions Academy.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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“…The term was coined by Prusiner in 1982 and means “proteinaceous infectious particles” [ 184 , 185 ]. These are NDG diseases induced by the natural transformation of a neuronal natural membrane protein called PrP C (cell prionic protein), a membrane glycoprotein that presents two helixes and two complex oligosaccharide chains coupled at the N-terminal head [ 186 ].…”