Lysosomal Channels as New Molecular Targets in the Pharmacological Therapy of Neurodegenerative Diseases

Besides controlling several organellar functions, lysosomal channels also guide the catabolic "self-eating" process named autophagy, which is mainly involved in protein and organelle quality control. Neuronal cells are particularly sensitive to the rate of autophagic flux either under physiological conditions or during the degenerative process. Accordingly, neurodegeneration occurring in Parkinson's (PD), Alzheimer's (AD), and Huntington's Diseases (HD), and Amyotrophic Lateral Sclerosis (ALS) as well as Lysosomal Storage Diseases (LSD) is partially due to defective autophagy and accumulation of toxic aggregates. In this regard, dysfunction of lysosomal ionic homeostasis has been identified as a putative cause of aberrant autophagy. From a therapeutic perspective, Transient Receptor Potential Channel Mucolipin 1 (TRPML1) and Two-Pore Channel isoform 2 (TPC2), regulating lysosomal homeostasis, are now considered promising druggable targets in neurodegenerative diseases. Compelling evidence suggests that pharmacological modulation of TRPML1 and TPC2 may rescue the pathological phenotype associated with autophagy dysfunction in AD, PD, HD, ALS, and LSD. Although pharmacological repurposing has identified several already used drugs with the ability to modulate TPC2, and several tools are already available for the modulation of TRPML1, many efforts are necessary to design and test new entities with much higher specificity in order to reduce dysfunctional autophagy during neurodegeneration.