Mechanism of Action of Lactacystin, a Microbial Substance Having NGF-like Action

本研究通过对微生物神经突发生诱导剂lactacystin在Neuro 2a细胞中的作用机制的研究，获得了以下结果.用lactacystin（1.3 μ M）处理细胞后，乙酰胆碱酯酶活性显著增强。因此，lactacystin除了形态学上的作用外，还被证实具有诱导Neuro 2a细胞分化的功能. Actacystin的作用机制与cAMP水平增强物质（二丁酰1-cAMP、毛喉素等）不同。和蛋白激酶抑制剂（H-7等）已知其在细胞中诱导轴突发生。蛋白磷酸酶抑制剂Calycuin A在lactacystin处理后1天内可抑制偶极神经突起的生长，提示蛋白磷酸酶参与偶极神经突起的生长。但calyculin A在处理后3d对神经网络的形成无影响. Lactacystin通过G1/G2阻滞抑制Neuro 2a细胞的细胞周期。此外，发现组蛋白脱乙酰酶抑制剂阿司他丁A（270 nM）可诱导细胞中的神经突发生。Tricostatin A诱导的神经网络至少维持21天.以较高的收率建立了lctacystin的全合成方法。

The following results were obtained in the study of the mechanism of action of the microbial neuritogenesis inducer lactacystin in Neuro 2a cells.1. Acetylcholineesterase activity in the cells was significantly enhanced by the treatment with lactacystin (1.3muM). Thus, lactacystin was proved functionally in addition to morpholotgically to induce the differentiation of Neuro 2a cells.2. The mechanism of action of actacystin was proved to be differentiated from those of cAMP level enhancing substances (dibutyry1-cAMP, forskolin etc.) and protein kinase inhibitors (H-7 etc.) which are known to induce neuritogenesis in the cells.3. Calycuin A, a protein phosphatase inhibitor, was shown to inhibit dipolar neurite outgrowth occurred in 1 day after the treatment with lactacystin, sugtgesting that protein hosphatases are involved in the dipolar neutite outgrowth. Hoever, calyculin A did not affect the formation of the network 3days after the treatment.4. Lactacystin inhibits the cell cycle of Neuro2a cell by G1/G2 arrest. Furthermore, the histone deacetylase inhibitors trichostatin A (270nM) was found to induce neuritegenesis in the cells. The network induced with tricostatin A was kept for at least 21days.5. Total synthesis of lctacystin was established with a high yield.