Induction of Exocytosis Rescues Lysosomal GM2 Accumulation in Tay-Sachs Disease

Abstract

Introduction. The Tay-Sachs disease is a progressive neurodegenerative disorder that is caused by a genetic mutation in the HEXA gene coding the lysosomal α-subunit of β-hexosaminidase A. Currently, there is no effective treatment for Tay-Sachs. Induction of exocytosis as a potential treatment approach is suggested to restore lysosomal enlargement in several lysosomal storage diseases. Here, we aimed to test the therapeutic potential of two small molecules, δ-tocopherol and hydroxypropyl-β-cyclodextrin, in fibroblast and neuroglia cells derived from Hexa-/-Neu3-/- mice and Tay-Sachs patients. Method. The effect of two small molecules on lysosomal enlargement and GM2 accumulation in lysosomes was examined by LysoTracker staining and immunocytochemical colocalization analysis for GM2 and LAMP1. qRT-PCR and fluorometric enzyme assay were also used to investigate the effect of combined treatment on the level of neuraminidase 1, a negative regulator of exocytosis. Results. Single treatment with δ-tocopherol (5-40 μM) and hydroxypropyl-β-cyclodextrin (10-50 μM) for 48 hours led to significant induction of lysosomal exocytosis. We demonstrated that the combined treatment with δ-tocopherol (10 μM) and hydroxypropyl-β-cyclodextrin (25 μM) resulted in a significant reduction of lysosomal GM2 and downregulation of lysosomal Neu1 expression. Conclusion. In this study, we demonstrated that inducing exocytosis by δ-tocopherol and hydroxypropyl-β-cyclodextrin might have therapeutic potential to reduce GM2 storage and pathology in Tay-Sachs cells.