Horton C D, Qi Y, Chikaraishi D, Wang J K
Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA.
J Neurochem. 2001 Jan;76(1):201-9. doi: 10.1046/j.1471-4159.2001.00017.x.
The mechanisms for neuronal survival in the CNS are not well understood, but are likely to be complex due to possible autocrine and redundant neurotrophic support. Most studies have focused on the nerve growth factor (NGF)/TrkA pathway in peripheral neurons, and little is known regarding the other neurotrophins, particularly neurotrophin-3 (NT3)/TrkC. Progress has also been hampered by the paucity of homogenous and accessible CNS neuronal experimental models. We now report that the novel catecholaminergic CNS cell line, CAD, is capable of autocrine survival mediated by NT3. The CAD cell is of CNS neuronal origin and can survive and morphologically differentiate in the absence of exogenously provided trophic factors. However, neutralizing reagents against NT3 (the neutralizing TrkC-IgG fusion protein and anti-NT3 antibodies), but not those that block the other neurotrophins, inhibited survival of differentiating CAD cells. Moreover, Trk phosphorylation was detected in CAD cells and its inhibition by K252a was correlated with K252a-induced apoptosis. Finally, endogenous NT3 was detectable in CAD cell extracts by a specific ELISA assay. Thus, CAD cells possess an autocrine survival capability mediated by NT3, and may provide a valuable model system for studying the signaling pathways that mediate the actions of this little understood neurotrophin.
中枢神经系统中神经元存活的机制尚未完全明确，但由于可能存在自分泌和冗余的神经营养支持，其机制可能较为复杂。大多数研究都集中在外周神经元中的神经生长因子（NGF）/TrkA 途径，而对于其他神经营养因子，尤其是神经营养因子-3（NT3）/TrkC 的了解甚少。同时，由于缺乏同质且易于获取的中枢神经系统神经元实验模型，相关研究进展也受到了阻碍。我们现在报告一种新的儿茶酚胺能中枢神经系统细胞系 CAD，它能够通过 NT3 介导自分泌存活。CAD 细胞起源于中枢神经系统神经元，在没有外源性提供的营养因子的情况下也能存活并发生形态分化。然而，针对 NT3 的中和试剂（中和性 TrkC-IgG 融合蛋白和抗 NT3 抗体），而非阻断其他神经营养因子的试剂，会抑制分化中的 CAD 细胞的存活。此外，在 CAD 细胞中检测到了 Trk 磷酸化，并且 K252a 对其的抑制与 K252a 诱导的细胞凋亡相关。最后，通过特异性 ELISA 检测在 CAD 细胞提取物中可检测到内源性 NT3。因此，CAD 细胞具有由 NT3 介导的自分泌存活能力，并且可能为研究介导这种了解较少的神经营养因子作用的信号通路提供一个有价值的模型系统。
