Finkbeiner S, Greenberg M E
Department of Neurology, Children's Hospital, Boston, MA 02155, USA.
Bioessays. 1997 Aug;19(8):657-60. doi: 10.1002/bies.950190803.
A key characteristic of an animal's nervous system is that it can respond to brief environmental stimuli with lasting changes in its structure and function. These changes are triggered by specific patterns of neuronal electrical activity and are manifested as changes in the strength and patterns of synaptic connectivity between activated neurons. The biochemical mechanisms that control these changes are unclear, but cytoplasmic rises in Ca2+ levels may play a critical role, especially in regulating neuronal gene expression for making activity-induced synaptic changes permanent. Recently, two reports have explored the spatial features by which activity-induced rises in Ca2+ levels activate transcription factors and gene expression. The reports suggest that Ca2+ influx acts both locally at the synapse and distantly within the nucleus to regulate transcription factors and gene expression. The results also show that regulatory elements within genes can respond differentially, depending on spatial differences in intracellular Ca2+ rises. These reports suggest new spatial mechanisms by which Ca(2+)-dependent gene expression could contribute to activity-dependent synaptic changes.
动物神经系统的一个关键特征是，它能够对短暂的环境刺激做出反应，其结构和功能会发生持久变化。这些变化由神经元电活动的特定模式触发，并表现为激活神经元之间突触连接强度和模式的变化。控制这些变化的生化机制尚不清楚，但细胞质中钙离子（Ca2+）水平的升高可能起着关键作用，尤其是在调节神经元基因表达以使活动诱导的突触变化永久化方面。最近，有两篇报告探讨了活动诱导的Ca2+水平升高激活转录因子和基因表达的空间特征。报告表明，Ca2+内流在突触局部和细胞核内远距离发挥作用，以调节转录因子和基因表达。结果还表明，基因内的调控元件可以根据细胞内Ca2+升高的空间差异做出不同反应。这些报告提出了新的空间机制，通过这些机制，依赖Ca2+的基因表达可能有助于依赖活动的突触变化。
