Regulation of N-acetylaspartate and N-acetylaspartylglutamate biosynthesis by protein kinase activators
Regulation of N-acetylaspartate and N-acetylaspartylglutamate biosynthesis by protein kinase activators
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DOI：
10.1111/j.1471-4159.2006.04068.x
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发表时间：
2006-09-01
影响因子：
4.7
通讯作者：
Namboodiri, M. A. Aryan
中科院分区：
文献类型：
--
作者：
Arun, Peethambaran;Madhavarao, Chikkathur N.;Namboodiri, M. A. Aryan
神经元二肽N-乙酰基天冬氨酸（NAAG）被认为是由N-乙酰基天冬氨酸（NAA）和谷氨酸酶促合成的。我们使用放射性标记的前体来检测用蛋白激酶A（dbcAMP; N6，2 '-O-二丁酰cAMP）和蛋白激酶C（PMA;佛波醇-12-肉豆蔻酸酯-13-乙酸酯）的激活剂刺激的SH-SY 5 Y人神经母细胞瘤细胞中NAA和NAAG的生物合成。在几天的过程中与dbcAMP的分化导致增加内源性NAA水平和NAAG合成从L-[H-3]谷氨酰胺，而PMA诱导的分化减少两者。外源施加NAA引起细胞内NAA水平的剂量依赖性增加，和NAAG生物合成从L-[H-3]谷氨酰胺，这表明NAA和NAAG之间的代谢产物和质量作用关系。L-[H-3]天冬氨酸依次掺入NAA和NAAG中，NAA在1h出现，而NAAG在6 ~ 24 h才出现。24 h时，dbcAMP可促进L-[H-3]天冬氨酸合成NAAG，PMA可抑制NAAG合成。PMA对L-[H-3]天冬氨酸掺入NAA的影响呈时间双相性。使用较短的孵育时间（1和6小时），PMA增加L-[H-3]天冬氨酸掺入到NAA中，但随着较长的孵育时间（24小时），掺入显着减少。这些结果表明，虽然神经元生产的NAA和NAAG的生物化学相关，显着差异存在于控制其生物合成的调节机制。
The neuronal dipeptide N-acetylaspartylglutamate (NAAG) is thought to be synthesized enzymatically from N-acetylaspartate (NAA) and glutamate. We used radiolabeled precursors to examine NAA and NAAG biosynthesis in SH-SY5Y human neuroblastoma cells stimulated with activators of protein kinase A (dbcAMP; N6,2'-O-dibutyryl cAMP) and protein kinase C (PMA; phorbol-12-myristate-13-acetate). Differentiation over the course of several days with dbcAMP resulted in increased endogenous NAA levels and NAAG synthesis from L-[H-3]glutamine, whereas PMA-induced differentiation reduced both. Exogenously applied NAA caused dose dependent increases in intracellular NAA levels, and NAAG biosynthesis from L-[H-3]glutamine, suggesting precursor-product and mass-action relationships between NAA and NAAG. Incorporation of L-[H-3]aspartate into NAA and NAAG occurred sequentially, appearing in NAA by 1 h, but not in NAAG until between 6 and 24 h. Synthesis of NAAG from L-[H-3]aspartate was increased by dbcAMP and decreased by PMA at 24 h. The effects of PMA on L-[H-3]aspartate incorporation into NAA were temporally biphasic. Using short incubation times (1 and 6 h), PMA increased L-[H-3]aspartate incorporation into NAA, but with longer incubation (24 h), incorporation was significantly reduced. These results suggest that, while the neuronal production of NAA and NAAG are biochemically related, significant differences exist in the regulatory mechanisms controlling their biosynthesis.