(703d) A Polyvalent Cell Engineering Strategy to Enhance Intracellular Clearance

Lysosomes are membrane-enclosed organelles rich in lytic enzymes capable of breaking down a variety of biomolecules, such as proteins, lipids and carbohydrates. They function as the cell’s waste disposal system, as they provide a site of degradation for material taken up from the extracellular space or intracellular waste products. Impairment of lysosomal degradation often leads to the accumulation of storage material and to the development of devastating human diseases collectively referred to as lysosomal storage disorders (LSDs).  LSDs are clinically highly diverse and can affect most organs, often as part of a multisystem disorder. The most severe forms affect the brain, causing progressive neurodegeneration and early death, and are presently incurable. Several experimental treatments are currently being tested in animal models of LSDs, which address the substitution of the single gene or protein defective in the specific LSD. However, these approaches have severe intrinsic limitations to brain targeting due to the presence of the blood-brain barrier (BBB). The BBB actually separates brain tissues from the body’s bloodstream, thus limiting the permeability to molecules, proteins, and DNA-containing vectors that may be used as therapeutic agents. In addition, these approaches are disease-specific, which often means that the knowledge gained in the development of a treatment for a given LSD is usually not directly transferrable to other LSDs. We describe here a polyvalent therapy against multiple neurodegenerative LSDs. We designed a strategy to modulate endogenous cellular pathways involved in lysosomal biogenesis and function, including the folding and processing of lysosomal proteins and autophagic processes. Particularly, we used chemical and biological approaches to activate the transcription factor EB, a master regulator of lysosomal biogenesis. We observed modulation of the transcription factor EB dependent network in association with rescue of common features of LSDs such as the impairment of lysosomal function and the accumulation of undegraded storage material. We also demonstrate that this strategy can be used to promote clearance of cytoplasmic proteinaceous aggregates through chaperone-mediated autophagy, thus suggesting that this strategy could potentially impact a number of clinically distinct human diseases ranging from early childhood lysosomal LSD to late-onset neurodegenerative diseases, such as Alzheimer’s, Parkinson’s and Huntington’s diseases.