Hapln4/Bral2 is a selective regulator for formation and transmission of GABAergic synapses between Purkinje and deep cerebellar nuclei neurons
Hapln4/Bral2 is a selective regulator for formation and transmission of GABAergic synapses between Purkinje and deep cerebellar nuclei neurons
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DOI：
10.1111/jnc.14571
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发表时间：
2018-12-01
影响因子：
4.7
通讯作者：
Oohashi, Toshitaka
中科院分区：
文献类型：
--
作者：
Edamatsu, Midori;Miyano, Rinako;Oohashi, Toshitaka
浦肯野细胞（Purkinje cells，PC）是小脑皮质向小脑深核（deep cerebellar nucleus，DCN）输出信号的主要细胞。DCN神经元包裹在密集组织的细胞外基质结构中，称为神经元周网（PNN）。PNN通常存在于表达小清蛋白的快速尖峰GABA能中间神经元周围，但有趣的是也存在于其他神经元周围，例如DCN和斜方体内侧核中的神经元，其是适于快速信号传导的大轴体突触的突触后神经元。这种特征性的定位促使人们假设PNN可能在大型快速信号突触的维持和形成中发挥作用。为了阐明PNN在这些突触中的作用，我们研究了出生后第14天（P）左右透明质酸和蛋白聚糖结合连接蛋白4（Hapln 4/Bral 2）敲除（KO）小鼠DCN突触的电生理和形态学特性。Hapln 4/Bral 2对PNN结构很重要，因为它稳定透明质酸和蛋白聚糖之间的相互作用。在这里，使用免疫组织化学，我们表明，Hapln 4/Bral 2定位与GABA能末梢密切。在Hapln 4/Bral 2 KO小鼠的DCN神经元中，与野生型小鼠相比，抑制性突触强度降低，而兴奋性突触的性质不受影响。IPSC振幅的降低主要是因为可释放囊泡的数量减少。此外，Hapln 4/Bral 2缺陷减少了DCN中PC GABA能终末的数量。这些结果表明，Hapln 4/Bral 2是PNN组分，其选择性地有助于小脑中PC-DCN突触的形成和传递。
Purkinje cells (PCs) convey the sole output of the cerebellar cortex to the deep cerebellar nuclei (DCN). DCN neurons are enwrapped in densely organized extracellular matrix structures, known as perineuronal nets (PNNs). PNNs are typically found around fast-spiking GABAergic interneurons expressing parvalbumin but interestingly also exist surrounding other neurons, such as the neurons in the DCN and medial nucleus of the trapezoid body, which are the post-synaptic neurons of large axo-somatic synapses adapted for fast signaling. This characteristic localization prompted the hypothesis that PNNs might play a role in the maintenance and formation of large fast-signaling synapses. To elucidate the role of the PNN at these synapses, we investigated the electrophysiological and morphological properties of DCN synapses in hyaluronan and proteoglycan binding link protein 4 (Hapln4/Bral2) knockout (KO) mice around postnatal day (P)14. Hapln4/Bral2 is important for PNN structure, as it stabilizes the interaction between hyaluronan and proteoglycan. Here, using immunohistochemistry we show that Hapln4/Bral2 localized closely with GABAergic terminals. In DCN neurons of Hapln4/Bral2 KO mice, inhibitory synaptic strengths were reduced as compared to those in wild-type mice, whereas the properties of excitatory synapses were unaffected. The reduced IPSC amplitudes were mainly because of reduced numbers of releasable vesicles. Moreover, Hapln4/Bral2 deficiency reduced the number of PC GABAergic terminals in the DCN. These results demonstrate that Hapln4/Bral2 is a PNN component that selectively contributes to formation and transmission of PC-DCN synapses in the cerebellum.