The role of MAP1A light chain 2 in synaptic surface retention of Cav2.2 channels in hippocampal neurons.
The role of MAP1A light chain 2 in synaptic surface retention of Cav2.2 channels in hippocampal neurons.
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DOI：
10.1523/jneurosci.3078-08.2008
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发表时间：
2008-10-29
期刊：
影响因子：
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通讯作者：
Sheng ZH
中科院分区：
文献类型：
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作者：
Leenders AG;Lin L;Huang LD;Gerwin C;Lu PH;Sheng ZH
Cav2.2通道定位于神经末梢，在神经传递中起关键作用。然而，控制这些通道表面滞留的决定因素尚未确定。在这里，我们报道了Cav2.2的突触前表面定位是通过它与微管相关蛋白MAP1A的轻链2(LC2)的相互作用来介导的。Cav2.2C末端23个残基结合域(BD)的缺失导致突触通道突触分布减少。使用针对Cav2.2细胞外表位产生的抗体，我们证明了干扰与Lc2的相互作用减少了突触前突触周围内源性Cav2.2的表面表达。此外，Lc2-Cav2.2偶联的破坏减少了通过Cav2.2进入神经末梢的钙离子内流，并损害了活动依赖的FM4-的摄取。用Latrunculin A处理神经元以破坏肌动蛋白细丝，导致表面Cav2.2阳性突起密度降低。此外，缺失肌动蛋白结合域的Lc2截短突变体Lc2NT在用RNAi抑制Lc2表达后，不能挽救Cav2.2的表面表达。由于肌动蛋白细丝是突触前突触的主要细胞成分，这些观察结果提示了一种机制，即Lc2提供了表面Cav2.2与肌动蛋白细胞骨架的锚定，从而有助于突触前功能。
Cav2.2 channels are localized at nerve terminals where they play a critical role in neurotransmission. However, the determinant that controls surface retention of these channels has not been identified. Here, we report that presynaptic surface localization of Cav2.2 is mediated through its interaction with light chain 2 (LC2) of microtubule-associated protein MAP1A. Deletion of a 23-residue binding-domain (BD) within the Cav2.2 C-terminus resulted in reduced synaptic distribution of the mutant channels. Using an antibody generated against an extracellular epitope of Cav2.2, we demonstrate that interfering the interaction with LC2 reduced surface expression of endogenous Cav2.2 at presynaptic boutons. In addition, the disruption of LC2-Cav2.2 coupling reduced Ca2+-influx into nerve terminals through Cav2.2 and impaired activity-dependent FM4-64 uptake. The treatments of neurons with Latrunculin A to disrupt actin filaments resulted in reduced density of surface Cav2.2-positive boutons. Furthermore, LC2NT, a LC2 truncated mutant lacking the actin-binding domain, could not rescue Cav2.2 surface expression after suppressing LC2 expression with RNAi. Since actin filaments are major cytomatric components at the presynaptic boutons, these observations suggest a mechanism by which LC2 provides anchoring of surface Cav2.2 to the actin cytoskeleton, thus contributing to presynaptic function.