Action potential-coupled Rho GTPase signaling drives presynaptic plasticity.
Action potential-coupled Rho GTPase signaling drives presynaptic plasticity.
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DOI：
10.7554/elife.63756
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发表时间：
2021-07-16
期刊：
影响因子：
7.7
通讯作者：
Soderling SH
中科院分区：
文献类型：
--
作者：
O'Neil SD;Rácz B;Brown WE;Gao Y;Soderblom EJ;Yasuda R;Soderling SH
与突触后信号传导相比，活动依赖的细胞骨架信号传导对突触前可塑性的贡献仍然存在争议，并且知之甚少。为了识别和评估这些信号通路，我们使用体内生物素鉴定（iBioID）对突触前细胞基质进行了蛋白质组学分析。由此产生的蛋白质组富含肌动蛋白细胞骨架调节因子，包括Rac1，这是一种激活Arp2/3复合物以形成分支肌动蛋白丝的Rho GTPase。引人注目的是，我们发现Rac1和Arp2/3与成年小鼠的突触囊泡膜密切相关。使用三种独立的方法来改变突触前Rac1活性（基因敲除、空间限制性抑制和时间光遗传学操作），我们发现该途径负调控兴奋性和抑制性突触的突触囊泡补充，双向塑造短期突触抑制。最后，我们使用双光子荧光寿命成像显示突触前Rac1激活是通过电压门控钙内流耦合到动作电位的。因此，这项研究揭示了一个以前未被认识的肌动蛋白调节的短期突触前可塑性的机制，该机制在兴奋性和抑制性终端上是保守的。它还为更好地理解突触前生理学提供了一个新的蛋白质组学框架，并为分离无处不在的表达蛋白的突触前效应提供了实验策略蓝图。
In contrast to their postsynaptic counterparts, the contributions of activity-dependent cytoskeletal signaling to presynaptic plasticity remain controversial and poorly understood. To identify and evaluate these signaling pathways, we conducted a proteomic analysis of the presynaptic cytomatrix using in vivo biotin identification (iBioID). The resultant proteome was heavily enriched for actin cytoskeleton regulators, including Rac1, a Rho GTPase that activates the Arp2/3 complex to nucleate branched actin filaments. Strikingly, we find Rac1 and Arp2/3 are closely associated with synaptic vesicle membranes in adult mice. Using three independent approaches to alter presynaptic Rac1 activity (genetic knockout, spatially restricted inhibition, and temporal optogenetic manipulation), we discover that this pathway negatively regulates synaptic vesicle replenishment at both excitatory and inhibitory synapses, bidirectionally sculpting short-term synaptic depression. Finally, we use two-photon fluorescence lifetime imaging to show that presynaptic Rac1 activation is coupled to action potentials by voltage-gated calcium influx. Thus, this study uncovers a previously unrecognized mechanism of actin-regulated short-term presynaptic plasticity that is conserved across excitatory and inhibitory terminals. It also provides a new proteomic framework for better understanding presynaptic physiology, along with a blueprint of experimental strategies to isolate the presynaptic effects of ubiquitously expressed proteins.