Nerve Growth Factor-Induced Neurite Outgrowth and MAP Kinase

I.当用NGF培养PC 12 D细胞时，即使RNA合成被阻断，也促进了突起的生长。神经突的生长也刺激成纤维细胞生长因子（FGF），并轻微刺激表皮生长因子（EGF）。MAP激酶的激活与PC 12 D细胞对各种药物的反应中神经突的生长之间的密切关系表明，激酶的激活可能在神经突的生长中起重要作用。详细情况见参考文献1.ii。当用DEAE-Sepharose柱分离来自对照和NGF-或dbcAMP-处理的PC 12 D细胞提取物的上清液级分时，在来自NGF-、FGF-和EGF-处理的细胞提取物的情况下，注意到磷酸化微管相关蛋白的第3峰中的激酶活性增强。峰1中的激酶活性在dbcAMP处理的细胞的情况下增强。这些观察结果加强了c 关于我们 神经突起的生长与神经生长因子依赖的MAP激酶的激活之间失去联系。详细情况见参考文献2.iii。PC 12 D细胞的形态在响应于各种药剂的快速变化进行了研究，在随后的突起的生长。PC 12 D细胞上的各种神经突促进剂引起细胞周围的皱褶，同时将F-肌动蛋白重新定位到皱褶区域。皱褶的形成可能是突起生长的最早阶段之一，其形态学变化可能是由特定蛋白激酶激活引起的。详细信息见参考文献3.iv。星形孢菌素引起培养的鸡胚背根神经节和PC 12 D细胞的神经突起的快速生长。通过电子显微镜和肌动蛋白和微管蛋白的细胞化学染色评估，神经突的向外生长与NGF诱导的神经突没有区别。然而，在无血清条件下，星形孢菌素从未像NGF那样促进PC 12 D细胞的存活。少

i. When PC12D cells were cultured with NGF, outgrowth was neurites was promoted even when RNA synthesis was blocked. The outgrowth of neurites was also stimulated in response to fibroblast growth factor (FGF) and was slightly stimulated in response to epidermal growth factor (EGF). The close relationship between the activation of MAP kinase and outgrowth of neurites from PC12D cells in response to various agents suggests that activation of the kinase may play an important role in the outgrowth of neurites. Detailes were published in ref.no.1.ii. When the supernatant fractions from extracts of control and NGF- or dbcAMP-treated PC12D cells were fractionated by DEAE-Sepharose column, enhancement of kinase activity in the 3rd peak that phosphorylate microtuble-associated proteins was noted in the case of the extracts from NGF-, FGF-, and of EGF-treated cells. The kinase activity in peak 1 was enhanced in the case of dbcAMP-treated cells. The observations strengthens the possibility of a c … More lose relationship between the outgrowth of neurites and and the activation of NGF-dependent MAP kinase. Detailes were published in ref. no.2.iii. Rapid changes in morphology of PC12D cells in response to various agents were studied in relation to the subsequent outgrowth of neurites. Various neurite-promoting agents on PC12D cells caused ruffling around the periphery of cells and simultaneous relocalization of F-actin to the area of ruffles. The formation of ruffles might be one of the earliest steps of the neurite outgrowth and the morphological change might ge triggered by the activation of specific protein kinases. Detailers were published in ref.no.3.iv. Staurosporine caused the rapid outgrowth of neurites from cultured dorsal root ganglia of chick embryos and from PC12D cells. the outgrowth of neurites were indistinguishable from those induced by NGF, as assessed by electron microscopy and and cytochemical staining of actin and tubulin. However, staurosporine never promoted survival of PC12D cells in serum-free conditions as that promoted by NGF.Detailes were published in ref.no.4. Less