Proteínas de prión : de la patogénesis a la función

Abstract

The prion protein (PrP) is a membrane-anchored glycoprotein normally present in all vertebrates. Under unusual circumstances, it can undergo structural transformation and become the sole constituent of prions, a unique class of infectious agent devoid of nucleic acid. Prions are the cause of a group of lethal neurodegenerative disorders that include Creutzfeldt-Jakob disease (CJD) in humans and bovine spongiform encephalopathy (BSE) or “mad cow disease”. Much is known about PrP’s pathogenic properties; however, its natural role remains elusive despite extensive characterization of its biochemical and cellular properties. Here we review prion diseases and their molecular basis, as well as the evolution and function of prion proteins. We include work carried out in our laboratory, particularly our analysis of PrP loss-of-function phenotypes in the zebrafish and the heterologous expression of various vertebrate PrPs in zebrafish, mouse and Drosophila cells. Our data show that an evolutionarily conserved function of all vertebtrate PrPs is the establishment of homotypic trans-interactions between neighboring cells, thus mediating cell contact formation and signaling via lipid rafts.