Patient-Derived Phenotypic High-Throughput Assay to Identify Small Molecules Restoring Lysosomal Function in Tay–Sachs Disease

Tay–Sachs disease is an inherited lysosomal storage disease resulting from mutations in the lysosomal enzyme, β-hexosaminidase A, and leads to excessive accumulation of GM2 ganglioside. Tay–Sachs patients with the infantile form do not live beyond 2–4 years of age due to rapid, progressive neurodegeneration. Enzyme replacement therapy is not a therapeutic option due to its inability to cross the blood–brain barrier. As an alternative, small molecules identified from high-throughput screening could provide leads suitable for chemical optimization to target the central nervous system. We developed a new high-throughput phenotypic assay utilizing infantile Tay–Sachs patient cells based on disrupted lysosomal calcium signaling as a monitor of diseased phenotype. The assay was validated in a pilot screen on a collection of Food and Drug Administration-approved drugs to identify compounds that could reverse or attenuate the disease. Pyrimethamine, a known pharmacological chaperone of β-hexosaminidase A, was identified from the primary screen. The mechanism of action of pyrimethamine in reversing the defective lysosomal phenotype was by improving autophagy. This new high-throughput screening assay in patient cells will enable the screening of larger chemical compound collections. Importantly, this approach could lead to identification of new molecular targets previously unknown to impact the disease and accelerate the discovery of new treatments for Tay–Sachs disease.