Association of GM4 Ganglioside with the Membrane Surrounding Lipid Droplets in Shark Liver

Yu-Teh Li,Eiko Sugiyama,Toshio Ariga,Jun Nakayama,Masayoshi Hayama,Yoichiro Hama,Hiroki Nakagawa,Tadashi Tai,Karol Maskos,Su-Chen Li,Takeshi Ksama

doi:10.1194/jlr.m200010-jlr200

Abstract

By TLC, GM4 was found to be the major ganglioside in the liver of six shark species examined: Odontaspis taurus, Negaprion brevirostris, Sphyrna lewini, Mustelus griseus, Mustelus manazo, and Prionace glauca. A detailed analysis of the glycosphingolipids (GSLs) in the liver of O. taurus (sand tiger shark) showed that it contained approximately 110 nmol of lipid-bound sialic acid per gram of wet tissue, of which 80% was GM4. By extracting the liver of O. taurus with chloroform/methanol, followed by chromatographic separation of GSLs using DEAE-Sephadex A-25 and Iatrobeads columns, we have isolated GM4 in pure form with a yield of approximately 5 mg per 100 g of wet tissue. The structures of both the sugar chain and the ceramide moiety of this GM4 were analyzed by chemical analysis, mass spectrometry, and NMR spectroscopy. Similar to GM4 isolated from other sources, 92% of fatty acids in the ceramide of this GM4 were 2-hydroxylated. However, unlike the long-chain bases found in other GSLs, the total long-chain bases in this GM4 were found to contain 43% octadecasphingenine and 50% nonadecasphingenine.Immunohistochemical analysis using a monoclonal antibody against GM4 revealed that the hepatocytes of both M. griseus (spotless smooth hound) and M. manazo (smooth hound) were filled with lipid droplets and GM4 was primarily associated with the membrane structure surrounding lipid droplets.

Highlights

By TLC, GM4 was found to be the major ganglioside in the liver of six shark species examined: Odontaspis taurus, Negaprion brevirostris, Sphyrna lewini, Mustelus griseus, Mustelus manazo, and Prionace glauca
While studying the distribution of glycosphingolipids (GSLs) in marine organisms, we found that the liver samples from six shark species that we examined were unusually rich in ganglioside GM4 when analyzed by TLC
The mono-sialoganglioside fraction obtained from DEAE-Sephadex-A-25 chromatography was dissolved in 1.5 ml of chloroform-methanol (9:1, v/v) and applied onto an Iatrobeads column (1.5 ϫ 35 cm) that had been equilibrated with the same solvent

Summary

Introduction

By TLC, GM4 was found to be the major ganglioside in the liver of six shark species examined: Odontaspis taurus, Negaprion brevirostris, Sphyrna lewini, Mustelus griseus, Mustelus manazo, and Prionace glauca. For the analysis of gangliosides in the liver of different shark species, 20 g of the liver sample from O. taurus, N. brevirostris, S. lewini, M. griseus, M. manazo, and P. glauca were sepatately extracted with 20 volumes of chloroform-methanol (1:1, v/v), subsequently passed through a DEAE-Sephadex column, and analyzed by TLC according to the procedure described by Ledeen et al [3].

Results

Conclusion