Variability of distribution of Ca(2+)/calmodulin-dependent kinase II at mixed synapses on the mauthner cell: colocalization and association with connexin 35.
Variability of distribution of Ca(2+)/calmodulin-dependent kinase II at mixed synapses on the mauthner cell: colocalization and association with connexin 35.
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DOI：
10.1523/jneurosci.4466-09.2010
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发表时间：
2010-07-14
期刊：
影响因子：
--
通讯作者：
Pereda AE
中科院分区：
文献类型：
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作者：
Flores CE;Cachope R;Nannapaneni S;Ene S;Nairn AC;Pereda AE
与化学传递相反，很少有蛋白质被证明与间隙连接介导的电突触相关。硬骨鱼Mauthner细胞上的混合（电和突触能）突触末梢被称为“俱乐部末梢”，因为它们不寻常的大尺寸和连接蛋白35（Cx 35）的存在，广泛分布的哺乳动物Cx 36的直系同源物，是研究电传递的有价值的模型。值得注意的是，它们的混合突触反应的两个成分都经历了活动依赖性增强。电传递的变化是由与共定位的突触的相互作用引起的，其活性导致Ca++/钙调蛋白依赖性激酶II（CaM-KII）的激活，这是诱导两种形式的传递变化所必需的。然而，这种激酶的分布和潜在的电突触定位仍然不确定。利用无与伦比的实验访问俱乐部的结局，我们探讨了这些终端内的存在和终端内分布的CaM-KII。在这里，我们显示：1）与其他蛋白质不同，CaM-KII的标记和分布在相邻接触之间高度可变，2）CaM-KII不仅限于末梢的周边，也存在于间隙连接占主导地位的中心。因此，双免疫标记表明，Cx 35和CaM-KII共定位和生化分析表明，这些蛋白质的关联。由于CaM-KII特征性地经历活性依赖性易位，所观察到的标记的可变性可能反映了连续俱乐部末梢的电突触之间的生理差异，其显著地与不同程度的电导共存。两者合计，我们的研究结果表明，CaM-KII应被认为是电突触的组成部分，虽然它的协会是非强制性的，并可能由活动驱动。
In contrast to chemical transmission, few proteins have been shown associated with gap junction-mediated electrical synapses. Mixed (electrical and glutamatergic) synaptic terminals on the teleost Mauthner cell known as “Club endings” constitute because of their unusual large size and presence of connexin 35 (Cx35), ortholog of the widespread mammalian Cx36, a valuable model for the study of electrical transmission. Remarkably, both components of their mixed synaptic response undergo activity-dependent potentiation. Changes in electrical transmission result from interactions with co-localized glutamatergic synapses, the activity of which leads to the activation of Ca++/calmodulin-dependent kinase II (CaM-KII), required for the induction of changes in both forms of transmission. However, the distribution of this kinase and potential localization to electrical synapses remains undetermined. Taking advantage of the unparalleled experimental accessibility of Club endings, we explored the presence and intraterminal distribution of CaM-KII within these terminals. Here we show: 1) unlike other proteins, both CaM-KII labeling and distribution were highly variable between contiguous contacts, and 2) CaM-KII was not restricted to the periphery of the terminals, where glutamatergic synapses are located, but also was present at the center where gap junctions predominate. Accordingly, double-immunolabeling indicated that Cx35 and CaM-KII were co-localized and biochemical analysis showed that these proteins associate. Because CaM-KII characteristically undergoes activity-dependent translocation, the observed variability of labeling likely reflects physiological differences between electrical synapses of contiguous Club endings, which remarkably co-exist with differing degrees of conductance. Taken together, our results indicate that CaM-KII should be considered a component of electrical synapses although its association is non-obligatory and likely driven by activity.