Neuroligin-2 accelerates GABAergic synapse maturation in cerebellar granule cells.
Neuroligin-2 accelerates GABAergic synapse maturation in cerebellar granule cells.
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DOI：
10.1016/j.mcn.2009.05.004
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发表时间：
2009-09
影响因子：
3.5
通讯作者：
Vicini, Stefano
中科院分区：
文献类型：
--
作者：
Fu, Zhanyan;Vicini, Stefano
神经连接蛋白(NLGS)是突触后细胞黏附分子，被认为在突触发生中起作用。为了探讨NLGS在突触形成后在突触传递中的作用，我们将神经连接素-2(NLG2)基因导入培养的小鼠小脑颗粒细胞(CGCs)，记录了GABA(γ-氨基丁酸)受体介导的微小突触后电流(MISPC)。在年轻的培养年龄(体外培养天数，DIV7-8)，NLG2转基因细胞的mIPSCs比表达GFP的对照细胞衰退更快。异构体特异性shRNA-NLG2对NLG2的下调作用则相反。我们和其他人已经证明，GABAA受体的α亚基从α2/3到α1的转换是包括小脑在内的不同中枢区域IPSC衰退的发育加速的基础。为了评估NLG2mIPSCs衰减时间的缩短是否是由于突触处招募了更多含有GABA-1的GABA受体，我们观察了唑吡坦延长电流衰减的作用，结果表明，唑吡坦优先增强含有α通道的α-1亚单位的活性。应用唑吡坦后，NLG2过表达细胞的突触电流延长动力学明显高于对照组，提示NLG2过表达通过促进未成熟细胞突触后部位含有α1亚单位的GABAARs的掺入而加速突触成熟。此外，当我们使用α1-/-小鼠的CGC培养物时，NLG2对突触电流衰减时间进程的加速的作用被取消。最后，为了排除NLG2对突触间隙GABA瞬变的影响也可能导致MIPSCs的快速衰退的可能性，我们测定了MIPSCs对快速消失的竞争拮抗剂TPMPA的敏感性。我们发现TPMPA类似地抑制对照组的mIPSCs和NLG2在幼年(DIV8)和老年(DIV14)培养时过表达CGCs。然而，我们证实了我们之前的发现，在年轻的(DIV8)培养中对mIPSCs的抑制比更成熟的(DIV14)培养的更大。综上所述，我们的结果表明，NLG2不改变GABA的独特释放，NLG2引起的mIPSC的快速衰减是由于突触后GABAA受体亚型的差异表达所致。综上所述，我们认为NLG-2在抑制突触发育和成熟中起重要作用。
Neuroligins (NLGs) are postsynaptic cell adhesion molecules that are thought to function in synaptogenesis. To investigate the role of NLGs on synaptic transmission once the synapse is formed, we transfected neuroligin-2(NLG2) in cultured mouse cerebellar granule cells (CGCs), and recorded GABAA (γ-aminobutyric acid) receptor mediated miniature postsynaptic currents (mISPCs). NLG2 transfected cells had mIPSCs with faster decay than matching GFP expressing controls at young culture ages (days in vitro, DIV 7-8). Down-regulation of NLG2 by the isoform specific shRNA-NLG2 resulted in an opposite effect. We and others have shown that the switch of α subunits of GABAA Rs from α2/3 to α1 underlies developmental speeding of the IPSC decay in various CNS regions, including the cerebellum. To assess whether the reduced decay time of mIPSCs by NLG2 is due to the recruitment of more α1 containing GABAARs at the synapses, we examined the prolongation of current decay by the zolpidem, which has been shown to preferentially enhance the activity of α1 subunit containing GABA channel. The application of zolpidem resulted in a significantly greater prolongation kinetics of synaptic currents in NLG2 over-expressing cells than control cells, suggesting that NLG2 over-expression accelerates synapse maturation by promoting incorporation of the α1 subunit-containing GABAARs at postsynaptic sites in immature cells. In addition, the effect of NLG2 on the speeding of decay time course of synaptic currents was abolished when we used CGC cultures from α1-/- mice. Lastly, to exclude the possibility that the fast decay of mIPSCs induced by NLG2 could be also due to the impacts of NLG2 on the GABA transient in synaptic cleft, we measured the sensitivity of mIPSCs to the fast-off competitive antagonists TPMPA. We found that TPMPA similarly inhibits mIPSCs in control and NLG2 over-expressing CGCs both at young age (DIV8) and old age (DIV14) of cultures. However, we confirm our previous finding of a greater inhibition of mIPSCs in young (DIV8) than more mature (DIV14) cultures. Together, our results suggest that NLG2 does not alter uniquantal GABA release, and the fast decay of mIPSC induced by NLG2 is due to the differential expression of postsynaptic GABAA receptor subtypes. Taken all together, we propose that NLG-2 plays important functional role in inhibitory synapse development and maturation.
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影响因子：
56.9
作者：
Biederer, T;Sara, Y;Südhof, TC
通讯作者：
Südhof, TC
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作者：
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通讯作者：
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影响因子：
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作者：
Fu, ZY;Washbourne, P;Vicini, S
通讯作者：
Vicini, S