Dissecting the impact of N-acetylmannosamine (ManNAc) on ganglioside levels in a sialin-deficient cell model.

Abstract

Lysosomal free sialic acid storage disorder (FSASD) is an ultra-rare neurodegenerative condition caused by mutations in SLC17A5 , which encodes the lysosomal sialic acid exporter, sialin. Deficiency of sialin leads to lysosomal accumulation of unconjugated ("free") sialic acid. This study investigated the ability of N-acetylmannosamine (ManNAc), a precursor of sialic acid, to rescue glycosphingolipid (GSL) sialylation in a SLC17A5-deficient HEK-293T model system. Our findings reveal that while ManNAc supplementation may enhance sialic acid biosynthesis, it does not fully restore ganglioside sialylation to wild-type levels, highlighting the essential role of lysosomal sialic acid recycling in maintaining GSL sialylation homeostasis.