Localized sphingolipid signaling at presynaptic terminals is regulated by calcium influx and promotes recruitment of priming factors.
Localized sphingolipid signaling at presynaptic terminals is regulated by calcium influx and promotes recruitment of priming factors.
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DOI：
10.1523/jneurosci.2808-12.2012
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发表时间：
2012-12-05
期刊：
影响因子：
--
通讯作者：
Sieburth D
中科院分区：
文献类型：
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作者：
Chan JP;Sieburth D
突触前功能的活动依赖性变化代表了控制突触强度的关键机制。然而，突触活动的变化如何耦合到突触前成分，以控制突触囊泡的释放和回收知之甚少。鞘氨醇激酶（SphK）是一种鞘脂代谢酶，其活性依赖性募集到突触前末梢内的膜区域，促进神经递质释放。在这里，我们表明SPHK-1的突触募集，SphK的直系同源物在C。elegans，是由突触前钙离子内流介导的。活体突触前末梢的定量荧光成像显示，阻断突触前钙离子内流会降低突触SPHK-1丰度，而增加钙离子内流会增加SPHK-1突触丰度。CALM-1是钙和整联蛋白结合蛋白（CIB）的直系同源物，与SPHK-1在释放位点共定位，并调节毒蕈碱介导的突触SPHK-1募集。我们确定了两个额外的鞘脂代谢酶，集中在突触前的终端，突变体缺乏其中之一，HYL-1/神经酰胺合酶，有缺陷的突触传递和突触囊泡循环。最后，我们表明，SPHK-1的活性是必要的启动蛋白的招聘？13/Munc 13突触前末梢激活毒蕈碱信号。这些研究结果表明，钙依赖性调节局部S1 P代谢的突触可能是一个重要的机制，突触囊泡启动因子被招募到释放网站，以促进突触传递。
Activity-dependent changes in presynaptic function represent a critical mechanism by which synaptic strength is controlled. However, how changes in synaptic activity couple to presynaptic components to control synaptic vesicle release and recycling are poorly understood. Sphingosine kinase (SphK) is a sphingolipid metabolic enzyme whose activity-dependent recruitment to membrane regions within presynaptic terminals promotes neurotransmitter release. Here, we show that synaptic recruitment of SPHK-1, the SphK ortholog in C. elegans, is mediated by presynaptic calcium influx. Quantitative fluorescence imaging of live presynaptic terminals reveals that blocking presynaptic calcium influx reduces synaptic SPHK-1 abundance whereas increasing calcium influx increases SPHK-1 synaptic abundance. CALM-1, the calcium and integrin binding protein (CIB) ortholog, co-localizes with SPHK-1 at release sites and regulates muscarinic-mediated synaptic SPHK-1 recruitment. We identify two additional sphingolipid metabolic enzymes that are concentrated at presynaptic terminals, and mutants lacking one of these, HYL-1/ceramide synthase, have defects in synaptic transmission and in synaptic vesicle cycling. Finally, we show that SPHK-1 activity is required for the recruitment of the priming protein UNC-13/Munc13 to presynaptic terminals following activation by muscarinic signaling. These findings suggest that calcium-dependent regulation of local S1P metabolism at synapses may be an important mechanism by which synaptic vesicle priming factors are recruited to release sites to promote synaptic transmission.