Kimmel Center for Biology and Medicine at the Skirball Institute and Department of Pharmacology, New York University School of Medicine, New York, New York, 10016, USA.
J Neurosci. 2012 Jan 11;32(2):599-609. doi: 10.1523/JNEUROSCI.2463-11.2012.
Neuronal activity elicits changes in synaptic composition that play an important role in experience-dependent plasticity (Choquet and Triller, 2003; Lisman and Raghavachari, 2006; Bourne and Harris, 2008; Holtmaat and Svoboda, 2009). We used a modified version of stable isotope labeling by amino acids in cell culture to identify activity-dependent modifications in the composition of postsynaptic densities (PSDs) isolated from rat primary neuronal cultures. We found that synaptic activity altered ∼2% of the PSD proteome, which included an increase in diverse RNA binding proteins (RNABPs). Indeed, 12 of the 37 identified proteins whose levels changed with synaptic activity were RNABPs and included the heterogeneous nuclear ribonucleoproteins (hnRNPs) G, A2/B1, M, and D. Knockdown of hnRNPs M and G using shRNAs resulted in altered numbers of dendritic spines, suggesting a crucial role for these proteins in spine density. Synaptic activity also resulted in a concomitant increase in dendritic and synaptic poly(A) mRNA. However, this increase was not affected by knockdown of hnRNPs M or G. Our results suggest that hnRNP proteins regulate dendritic spine density and may play a role in synaptodendritic mRNA metabolism.
神经元活动引发突触组成的变化，这些变化在经验依赖性可塑性中起着重要作用（Choquet 和 Triller，2003；Lisman 和 Raghavachari，2006；Bourne 和 Harris，2008；Holtmaat 和 Svoboda，2009）。我们使用细胞培养中的氨基酸稳定同位素标记的改良版本来鉴定从大鼠原代神经元培养物中分离的突触后密度（PSD）组成中的活性依赖性修饰。我们发现突触活动改变了 PSD 蛋白质组的约 2%，其中包括各种 RNA 结合蛋白（RNABP）的增加。实际上，在 37 种因突触活动而水平发生变化的鉴定蛋白中，有 12 种是 RNABP，包括核不均一核糖核蛋白（hnRNP）G、A2/B1、M 和 D。使用 shRNA 敲低 hnRNPs M 和 G 导致树突棘数量发生改变，表明这些蛋白在棘密度中起着关键作用。突触活动还导致树突和突触多聚（A）mRNA 的同时增加。然而，hnRNPs M 或 G 的敲低并不影响这种增加。我们的结果表明，hnRNP 蛋白调节树突棘密度，并可能在突触树突 mRNA 代谢中发挥作用。
