Riboni L, Bassi R, Conti M, Tettamanti G
Department of Medical Chemistry and Biochemistry, Medical School, University of Milan, Italy.
FEBS Lett. 1993 May 17;322(3):257-60. doi: 10.1016/0014-5793(93)81582-k.
Cerebellar granule cells, differentiated in vitro, were parallelly fed with [Sph-3H]GM1 and [stearoyl-14C]GM1, under identical conditions (10(-6) M ganglioside; pulse, from 1-4 h; chase, up to 24 h after 4 h pulse) and the salvage pathways of sphingosine and stearic acid were investigated. It was observed that both sphingosine and stearic acid, liberated during the intralysosomal degradation of ganglioside, are metabolically recycled, along distinct pathways. Sphingosine is used for the biosynthesis of a number of sphingolipids, particularly ceramide, glucosyl-ceramide, gangliosides and sphingomyelin; stearic acid is utilized for the biosynthesis of sphingolipids, and to a greater extent, glycero-phospholipids, especially those endogenously richer in stearic acid (phosphatidyl-ethanolamine and phosphatidyl-choline). No evidence was provided for a salvage pathway for ceramide.
在相同条件下（神经节苷脂浓度为10⁻⁶ M；脉冲时间为1至4小时；在4小时脉冲后追踪至24小时），对体外分化的小脑颗粒细胞同时给予[鞘氨醇-³H]GM1和[硬脂酰-¹⁴C]GM1，并研究鞘氨醇和硬脂酸的补救途径。结果发现，神经节苷脂在溶酶体内降解过程中释放的鞘氨醇和硬脂酸均沿不同途径进行代谢循环。鞘氨醇用于多种鞘脂的生物合成，特别是神经酰胺、葡糖神经酰胺、神经节苷脂和鞘磷脂；硬脂酸用于鞘脂的生物合成，并且在更大程度上用于甘油磷脂的生物合成，尤其是那些内源性富含硬脂酸的甘油磷脂（磷脂酰乙醇胺和磷脂酰胆碱）。未发现神经酰胺有补救途径的证据。
