Filipin recognizes both GM1 and cholesterol in GM1 gangliosidosis mouse brain

Filipin is an antibiotic polyene widely used as a histochemical marker for cholesterol. We previously reported cholesterol/filipin-positive staining in brain of beta-galactosidase (beta-gal) knockout (-/-) mice (GM1 gangliosidosis). The content and distribution of cholesterol and gangliosides was analyzed in plasma membrane (PM) and microsomal (MS) fractions from whole-brain tissue of 15 week-old control (beta-gal+/-) and GM1 gangliosidosis (beta-gal-/-) mice. Total ganglioside content (mu g sialic acid/mg protein) was 3-fold and 7-fold greater in the PM and MS fractions, respectively, in beta gal-/- mice than in beta gal+/- mice. GM1 content was 30-fold and 50-fold greater in the PM and MS fractions, respectively. In contrast, unesterified cholesterol content (mu g/mg protein) was similar in the PM and the MS fractions of the beta gal-/- and beta gal+/- mice. Filipin is known to bind to various sterol derivatives and phospholipids on thin-layer chromatograms. Biochemical evidence is presented showing that filipin also binds to GM1 with an affinity similar to that for cholesterol, with a corresponding fluorescent reaction. Our data suggest that the GM1 storage seen in the beta-gal-/- mouse contributes to the filipin ultraviolet fluorescence observed in GM1 gangliosidosis brain. The data indicate that in addition to cholesterol, filipin can also be useful for detecting GM1.-Arthur, J. R., K. A. Heinecke, and T. N. Seyfried. Filipin recognizes both GM1 and cholesterol in GM1 gangliosidosis mouse brain. J. Lipid Res. 2011. 52: 1345-1351.