A novel class of allosteric glucosylceramidase beta 1 correctors that reduce cellular stress and enhance lysosomal function

Abstract

Mutations in glucosylceramidase beta 1 (GCase) disrupt the protein conformational maturation in the endoplasmic reticulum (ER) and hinder its transport to the lysosome. The intralysosomal accumulation of glucocerebrosides, which are substrates of the GCase enzyme, impairs lysosomal function and is linked to Gaucher disease (GD). GCase mutations also increase the risk of Parkinson disease (PD) and Dementia with Lewy Bodies. We used Site-directed Enzyme Enhancement Therapy (SEE-Tx) technology to design two structurally targeted allosteric regulators (STARs) of GCase. Administration of GT-02287 and GT-02329 to cultured GD patient-derived primary human fibroblasts enhances folding and protects the two most common disease-causing GCase variants, GCaseAsn370Ser and GCaseLeu444Pro, from proteasomal degradation. Mechanistically, these treatments facilitate the lysosomal delivery of enzymatically active forms of mutant GCase, leading to improved lysosomal function and reduced cellular stress in GD patient-derived fibroblasts. The findings suggest that the allosteric pharmacologic regulators GT-02287 and GT-02329 hold promise for further development as potential therapeutic agents for GCase-related disorders, including GD, PD and Dementia with Lewy Bodies.