Neurodegenerative diseases in the era of targeted therapeutics: how to handle a tangled issue.

Neurodegenerative diseases are age-related and relentlessly progressive with increasing prevalence and no cure or lasting symptomatic therapy. The well-recognized prodromal phase in many forms of neurodegeneration suggests a prolonged period of neuronal compensated dysfunction prior to cell loss that may be amenable to therapeutic intervention. Although most efforts to date have been focused on misfolded toxic proteins, it is now clear that widespread changes in protein homeostasis occur early in these diseases and understanding this fundamental biology is key to the design of targeted therapies. What has emerged from molecular genetics and animal studies is a previously less appreciated association of neurodegenerative diseases with defects in the molecular regulation of protein trafficking between cellular organelles, especially the intricate network of endosomes, lysosomes, autophagosomes and mitochondria. Here we summarized the broader concepts that stemmed from this Special Issue on "Protein Clearance in Neurodegenerative diseases: from mechanisms to therapies". This article is part of a Special Issue entitled 'Neuronal Protein'.