2. Academic Validation
  3. Glucocerebrosidases catalyze a transgalactosylation reaction that yields a newly-identified brain sterol metabolite, galactosylated cholesterol

Glucocerebrosidases catalyze a transgalactosylation reaction that yields a newly-identified brain sterol metabolite, galactosylated cholesterol

  • J Biol Chem. 2020 Apr 17;295(16):5257-5277. doi: 10.1074/jbc.RA119.012502.
Hisako Akiyama 1,  Mitsuko Ide 2,  Yasuko Nagatsuka 3,  Tomoko Sayano 3,  Etsuro Nakanishi 4,  Norihito Uemura 4,  Kohei Yuyama 5,  Yoshiki Yamaguchi 6,  Hiroyuki Kamiguchi 1,  Ryosuke Takahashi 4,  Johannes M F G Aerts 7,  Peter Greimel 8,  Yoshio Hirabayashi 9
Affiliations

Affiliations

  • 1 RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan; RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
  • 2 RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan.
  • 3 RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
  • 4 Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
  • 5 Lipid Biofunction Section, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.
  • 6 Laboratory of Pharmaceutical Physical Chemistry, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan.
  • 7 Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden 2333 CC, The Netherlands.
  • 8 RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan.
  • 9 RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan. Electronic address: hirabaya@riken.jp.
PMID: 32144204 DOI: 10.1074/jbc.RA119.012502
Abstract

β-Glucocerebrosidase (GBA) hydrolyzes glucosylceramide (GlcCer) to generate ceramide. Previously, we demonstrated that lysosomal GBA1 and nonlysosomal GBA2 possess not only GlcCer hydrolase activity, but also transglucosylation activity to transfer the glucose residue from GlcCer to Cholesterol to form β-cholesterylglucoside (β-GlcChol) in vitro β-GlcChol is a member of sterylglycosides present in diverse species. How GBA1 and GBA2 mediate β-GlcChol metabolism in the brain is unknown. Here, we purified and characterized sterylglycosides from rodent and fish brains. Although glucose is thought to be the sole carbohydrate component of sterylglycosides in vertebrates, structural analysis of rat brain sterylglycosides revealed the presence of galactosylated Cholesterol (β-GalChol), in addition to β-GlcChol. Analyses of brain tissues from GBA2-deficient mice and GBA1- and/or GBA2-deficient Japanese rice fish (Oryzias latipes) revealed that GBA1 and GBA2 are responsible for β-GlcChol degradation and formation, respectively, and that both GBA1 and GBA2 are responsible for β-GalChol formation. Liquid chromatography-tandem MS revealed that β-GlcChol and β-GalChol are present throughout development from embryo to adult in the mouse brain. We found that β-GalChol expression depends on galactosylceramide (GalCer), and developmental onset of β-GalChol biosynthesis appeared to be during myelination. We also found that β-GlcChol and β-GalChol are secreted from neurons and glial cells in association with exosomes. In vitro Enzyme assays confirmed that GBA1 and GBA2 have transgalactosylation activity to transfer the galactose residue from GalCer to Cholesterol to form β-GalChol. This is the first report of the existence of β-GalChol in vertebrates and how β-GlcChol and β-GalChol are formed in the brain.

Keywords

brain; cholesterol; galactosylated cholesterol; glucocerebrosidase; glycolipid; mass spectrometry (MS); sterol; sterylglycoside; transglycosylation; β-cholesterylgalactoside.

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