Llansola M, Sáez R, Felipo V
Laboratory of Neurobiology, Instituto de Investigaciones Citologicas, Fundación Valenciana de Investigaciones Biomédicas, Amadeo de Saboya, 4. 46010 Valencia, Spain.
Eur J Neurosci. 2001 Apr;13(7):1283-91. doi: 10.1046/j.0953-816x.2001.01497.x.
Microtubule-associated protein MAP-2 is a neuronal phosphoprotein which modulates microtubule stability and spatial organization of signal transduction pathways. The functions of MAP-2 are modulated by phosphorylation. We studied the modulation of MAP-2 phosphorylation using the N-methyl- D-aspartate (NMDA) type of glutamate receptors and the signal transduction pathways mediating this modulation in primary cultures of rat cerebellar neurons. NMDA induced a rapid increase (330% of basal at 5 min) in MAP-2 phosphorylation which was not prevented by KN-62, indicating that it is not mediated by activation of Ca-calmodulin-dependent protein kinase. NMDA-induced phosphorylation of MAP-2 was inhibited by the nitric oxide synthase inhibitors nitroarginine and 7-nitroindazole and by PD098059 (an inhibitor of MAP kinase kinase), but was only slightly reduced by calphostin C or U-73122, inhibitors of protein kinase C and of phospholipase C, respectively. This indicates that the main pathway mediating NMDA-induced phosphorylation of MAP-2 is activation of nitric oxide synthase and subsequent activation of MAP kinase. We show that activation of NMDA receptors induces an activation of MAP kinase which is prevented by nitroarginine. The nitric oxide-generating agent (+/-)-S-nitroso-N-acetylpenicillamine (SNAP) also induced activation of MAP kinase and increased phosphorylation of MAP-2. Other nitric oxide-generating agents (NOC-18 and NOR-3) also increased MAP-2 phosphorylation. The interplay between NMDA receptors-associated signal transduction pathways and MAP-2 may be involved in the modulation of neuronal responses to extracellular signals and in the regulation of neuronal function.
微管相关蛋白MAP - 2是一种神经元磷蛋白，可调节微管稳定性和信号转导通路的空间组织。MAP - 2的功能受磷酸化作用调控。我们利用N - 甲基 - D - 天冬氨酸（NMDA）型谷氨酸受体以及介导这种调控的信号转导通路，在大鼠小脑神经元原代培养物中研究了MAP - 2磷酸化的调控。NMDA诱导MAP - 2磷酸化迅速增加（5分钟时为基础水平的330%），而KN - 62并不能阻止这种增加，这表明它不是由钙 - 钙调蛋白依赖性蛋白激酶的激活介导的。NMDA诱导的MAP - 2磷酸化受到一氧化氮合酶抑制剂硝基精氨酸和7 - 硝基吲唑以及PD098059（一种MAP激酶激酶抑制剂）的抑制，但仅被钙磷蛋白C或U - 73122（分别为蛋白激酶C和磷脂酶C的抑制剂）轻微降低。这表明介导NMDA诱导的MAP - 2磷酸化的主要途径是一氧化氮合酶的激活以及随后MAP激酶的激活。我们发现NMDA受体的激活诱导了MAP激酶的激活，而硝基精氨酸可阻止这种激活。一氧化氮生成剂（±）-S - 亚硝基 - N - 乙酰青霉胺（SNAP）也诱导了MAP激酶的激活并增加了MAP - 2的磷酸化。其他一氧化氮生成剂（NOC - 18和NOR - 3）也增加了MAP - 2的磷酸化。NMDA受体相关信号转导通路与MAP - 2之间的相互作用可能参与了神经元对细胞外信号反应的调节以及神经元功能的调控。
