Role of Enzymes in Prion Disease: A Molecular Mechanism

As an assortment of catastrophic neurodegenerative diseases, prion diseases are distinguished by the buildup of misfolded prion proteins in the brain and spinal cord. Due to exposure to these misfolded proteins, the normal cellular isoform prion protein (PrP-C) is converted into the disease-associated variant scrapie prion protein (PrP-Sc). The importance of enzymes in the etiology of prion disease has recently been elucidated by several research. During the initial stages of prion infection, host-encoded enzymes, such as protein disulfide isomerase, facilitate the conversion of PrP-C to PrP-Sc by promoting the formation of disulfide bonds. This conversion triggers a chain reaction, accumulating PrP-Sc aggregates that disrupt cellular functions and trigger neurotoxicity. Proteolytic enzymes, including cathepsins and matrix metalloproteinases, are involved in the progression of prion diseases. They participate in the proteolytic processing of PrP-Sc, generating shorter fragments that may serve as seeds for prion propagation. These enzymes can also facilitate the release and intercellular spread of prions by cleaving PrP-Sc from the cell surface or within endocytic compartments. Enzymatic activities are also implicated in the clearance of prions from the brain. Misfolded proteins, including PrP-Sc, undergo degradation through the ubiquitin-proteasome system and the autophagy pathways. Enzymes involved in these pathways, such as the E3 ubiquitin ligases and lysosomal hydrolases, are critical in targeting PrP-Sc for degradation and reducing its accumulation. Emerging therapeutic strategies for prion diseases aim to modulate the activity of enzymes involved in prion propagation and clearance. Novel drug candidates targeting specific enzymes, such as protein disulfide isomerase inhibitors or proteasomal degradation activators, have shown promising results in preclinical studies and hold potential for therapeutic interventions. In conclusion, enzymes play a multifaceted role in prion diseases, from facilitating the conversion of PrP-C to PrP-Sc to promoting prion propagation and clearance. Understanding the intricate interplay between enzymes and prion proteins is crucial for unraveling the molecular mechanisms underlying prion diseases and developing effective therapeutic approaches to combat these devastating disorders.