Schwartz M L, Shneidman P S, Bruce J, Schlaepfer W W
Division of Neuropathology, University of Pennsylvania Medical School, Philadelphia 19104-6069.
J Biol Chem. 1992 Dec 5;267(34):24596-600.
The levels of light, mid-sized, and heavy neurofilament (NF) mRNAs were compared to that of beta-actin mRNA in primary dissociated cultures of adult rat dorsal root ganglia (DRG). Decreases in the levels of all three NF mRNAs occur after 24 h in culture, mimicking the down-regulation of NF mRNAs in axotomized DRG neurons. The loss of NF mRNAs in DRG cultures is prevented by actinomycin and, to a lesser extent, by cycloheximide. Based on decay curves in actinomycin-treated cultures, the half-lives of NF mRNAs are at least 4 days in DRG neurons, but < 24 h in PC12 cells. Our data support the view that NF mRNAs are stabilized in DRG neurons and that stabilization prevents destabilization by a transcription-dependent process. We further propose that putative stabilizing factor(s) are able to prevent degradation of NF transcripts in intact neurons, but not in axotomized or cultured neurons.
在成年大鼠背根神经节（DRG）的原代解离培养物中，比较了轻、中、重神经丝（NF）mRNA水平与β-肌动蛋白mRNA水平。培养24小时后，所有三种NF mRNA水平均下降，这与轴突切断的DRG神经元中NF mRNA的下调情况相似。放线菌素可防止DRG培养物中NF mRNA的丢失，环己酰亚胺在较小程度上也有此作用。根据放线菌素处理培养物中的衰变曲线，DRG神经元中NF mRNA的半衰期至少为4天，但在PC12细胞中小于24小时。我们的数据支持这样的观点，即NF mRNA在DRG神经元中得到稳定，并且这种稳定通过转录依赖过程防止其不稳定。我们进一步提出，假定的稳定因子能够防止完整神经元中NF转录本的降解，但不能防止轴突切断或培养神经元中NF转录本的降解。
