Watanabe Hiroshi, Yamazaki Masakazu, Miyazaki Hideyuki, Arikawa Chihiro, Itoh Kouichi, Sasaki Takehiko, Maehama Tomohiko, Frohman Michael A, Kanaho Yasunori
Department of Pharmacology, The Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
J Neurochem. 2004 Apr;89(1):142-51. doi: 10.1111/j.1471-4159.2004.02308.x.
Stimulation of the neuronal cell adhesion molecule L1 in cerebellar granule neurons (CGNs) enhances neurite outgrowth and this response is inhibited by the primary alcohol ethanol. Because primary alcohols suppress the formation of the signaling lipid phosphatidic acid (PA) by phospholipase D (PLD), this observation prompted us to investigate whether PLD plays a role in the L1-mediated neurite outgrowth in CGNs. In the cerebellum of postnatal day 8 mice, PLD2 protein was abundantly expressed, while PLD1 expression was not detected. The L1-stimulated neurite outgrowth was inhibited by primary alcohols and by overexpression of lipase-deficient PLD2. Increases in cellular PA levels by direct PA application or overexpression of wild-type PLD2 mimicked the L1-dependent stimulation of neurite outgrowth. Furthermore, it was found that L1 stimulation in CGNs increased PLD activity concomitantly with phosphorylation of extracellular signal-regulated kinase (ERK), both of which were inhibited by the MAP kinase-ERK kinase (MEK) inhibitor. These results provide evidence that PLD2 functions as a downstream signaling molecule of ERK to mediate the L1-dependent neurite outgrowth of CGNs, a mechanism that may be related to alcohol-related neurodevelopmental disorders.
刺激小脑颗粒神经元（CGNs）中的神经元细胞粘附分子L1可增强神经突生长，而这种反应会被伯醇乙醇抑制。由于伯醇会抑制磷脂酶D（PLD）介导的信号脂质磷脂酸（PA）的形成，这一观察结果促使我们研究PLD是否在CGNs中L1介导的神经突生长中发挥作用。在出生后第8天小鼠的小脑中，PLD2蛋白大量表达，而未检测到PLD1的表达。L1刺激的神经突生长受到伯醇和脂肪酶缺陷型PLD2过表达的抑制。通过直接应用PA或野生型PLD2的过表达来提高细胞内PA水平，可模拟L1依赖的神经突生长刺激。此外，研究发现CGNs中的L1刺激会伴随着细胞外信号调节激酶（ERK）的磷酸化而增加PLD活性，而这两者均被丝裂原活化蛋白激酶-ERK激酶（MEK）抑制剂抑制。这些结果提供了证据，表明PLD2作为ERK的下游信号分子，介导CGNs中L1依赖的神经突生长，这一机制可能与酒精相关的神经发育障碍有关。
