Brain lipid profiling of triply mouse model with the deficiencies of sialidase neu1, neu4 and ß-hexosaminidase a enzymes

Abstract

Tay-Sachs disease is a severe lysosomal storage disorder caused by mutations in the HEXA gene coding for α subunit of lysosomal β-hexosaminidase A enzyme, which converts GM2 to GM3 ganglioside. HexA-/- mice, depleted of β-hexosaminidase A enzyme, remain asymptomatic to 1 year of age, so it was thought there is a difference between human and mice lipid degradation. Previously identified a novel ganglioside metabolizing sialidase, Neu4, is abundantly expressed in mouse brain neurons. It was demonstrated that mice with targeted disruption of both HexA and Neu4 genes (HexA-/- Neu4-/-) show accumulating GM2 ganglioside and epileptic seizures with 40% penetrance. Since all mice didn't show symptoms, it was suggested that Neu4 is not the only sialidase contributing to the metabolic bypass in HexA-/- mice (Seyrantepe et al. 2010). Therefore, we studied the role of another sialidase Neu 1 in glycolipid degradation. We profiled brain glycolipid content of triple deficient mouse model with the deficiency of β-hexosaminidase A (0% activity), sialidase Neu4 (0% activity) and sialidase Neu 1 (10% activity) (NeoIn) by thin layer chromatography. Analysis of both double (HexA-/-NeoIn-/-) and triple (HexA-/-Neu4-/-NeoIn-/-) mice models showed that sialidase Neu 1 deficency causes not significant difference in brain lipid profile and though also other sialidase/sialidases might have role in glycolipid degradation pathway in mice.