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
复制标题
DOI：
10.1074/jbc.ra119.012502
复制
发表时间：
2020-04-17
影响因子：
4.8
通讯作者：
Hirabayashi, Yoshio
中科院分区：
文献类型：
--
作者：
Akiyama, Hisako;Ide, Mitsuko;Hirabayashi, Yoshio
?-葡糖脑苷脂酶（GBA）水解葡糖神经酰胺（GlcCer）以产生神经酰胺。先前，我们证明了溶酶体GBA 1和非溶酶体GBA 2不仅具有GlcCer水解酶活性，而且具有转葡糖基化活性，将葡萄糖残基从GlcCer转移到胆固醇以形成？-胆甾醇葡萄糖苷（？GlcChol）。?- GlcChol是存在于不同物种中的甾醇糖苷的成员。GBA 1和GBA 2如何介导？大脑中的GlcChol代谢未知。在这里，我们纯化和特点sterylglycosides从啮齿动物和鱼的大脑。虽然葡萄糖被认为是脊椎动物中甾醇苷的唯一碳水化合物成分，但对大鼠脑甾醇苷的结构分析表明存在半乳糖基化胆固醇（？GalChol），此外？-胆固醇对GBA 2缺陷小鼠和GBA 1和/或GBA 2缺陷日本稻鱼（Oryzias latipes）脑组织的分析表明，GBA 1和GBA 2负责？GlcChol降解和形成，并且GBA 1和GBA 2都负责？- GalChol形成。液相色谱法？串联质谱显示，胆固醇和？- GalChol存在于小鼠大脑中从胚胎到成体的整个发育过程中。我们找到的？- GalChol的表达依赖于半乳糖神经酰胺（GalCer），GalChol生物合成似乎在髓鞘形成期间。我们还发现？-胆固醇和？- GalChol与外泌体一起由神经元和神经胶质细胞分泌。体外酶法证实GBA 1和GBA 2具有转半乳糖基活性，可将半乳糖残基从GalCer转移到胆固醇，形成？GalChol这是第一次报告的存在？GalChol在脊椎动物和如何？胆固醇和？- GalChol在大脑中形成。
?-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 ?-cholesterylglucoside (?-GlcChol) in vitro. ?-GlcChol is a member of sterylglycosides present in diverse species. How GBA1 and GBA2 mediate ?-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 (?-GalChol), in addition to ?-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 ?-GlcChol degradation and formation, respectively, and that both GBA1 and GBA2 are responsible for ?-GalChol formation. Liquid chromatography?tandem MS revealed that ?-GlcChol and ?-GalChol are present throughout development from embryo to adult in the mouse brain. We found that ?-GalChol expression depends on galactosylceramide (GalCer), and developmental onset of ?-GalChol biosynthesis appeared to be during myelination. We also found that ?-GlcChol and ?-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 ?-GalChol. This is the first report of the existence of ?-GalChol in vertebrates and how ?-GlcChol and ?-GalChol are formed in the brain.