Signal transmission at invaginating cone photoreceptor synaptic contacts following deletion of the presynaptic cytomatrix protein Bassoon in mouse retina
Signal transmission at invaginating cone photoreceptor synaptic contacts following deletion of the presynaptic cytomatrix protein Bassoon in mouse retina
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DOI：
10.1111/apha.13241
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发表时间：
2019-06-01
影响因子：
6.3
通讯作者：
Feigenspan, Andreas
中科院分区：
文献类型：
--
作者：
Babai, Norbert;Gierke, Kaspar;Feigenspan, Andreas
目的哺乳动物视网膜的一个关键特征是视觉信息在平行通路中的分离，从感光体末端开始。视锥光感受器与On双极细胞和水平细胞在内陷的含带突触部位建立突触接触，而Off双极细胞形成平坦的不含带接触。细胞基质蛋白Bassoon将条带锚定在活性区，其缺失诱导条带从活性区脱离。在这项研究中，我们调查的影响，一个失踪的巴松管在第一突触的视觉system.MethodsRelease特性的锥光感受器的突触传递进行了研究，在野生型和突变小鼠视网膜的遗传破坏的突触前细胞基质蛋白巴松管使用全细胞电压钳记录。光学和电子显微镜显示的分布Ca 2+通道和突触囊泡，分别在这两个小鼠line. ResultsWhole-cell记录从突触后水平细胞的两个小鼠line. ResultsBassoon（和一个丝带）的存在下，增强了在滋补和诱发的释放增加突触囊泡池的大小和补充率，而在同一时间减缓突触囊泡释放的胞吐率。此外，Ca（v）1.4通道和突触囊泡的数量显着高于野生型比在巴松管突变synaptic sites.ConclusionThe结果表明，谷氨酸释放从锥光感受器终端可以发生独立的突触带，但似乎仅限于活动区，它们显示了突触带在持续的、时空同步的神经递质释放中的重要性。
AimA key feature of the mammalian retina is the segregation of visual information in parallel pathways, starting at the photoreceptor terminals. Cone photoreceptors establish synaptic contacts with On bipolar and horizontal cells at invaginating, ribbon-containing synaptic sites, whereas Off bipolar cells form flat, non-ribbon-containing contacts. The cytomatrix protein Bassoon anchors ribbons at the active zone, and its absence induces detachment of ribbons from the active zone. In this study we investigate the impact of a missing Bassoon on synaptic transmission at the first synapse of the visual system.MethodsRelease properties of cone photoreceptors were studied in wild-type and mutant mouse retinae with a genetic disruption of the presynaptic cytomatrix protein Bassoon using whole-cell voltage-clamp recordings. Light and electron microscopy revealed the distribution of Ca2+ channels and synaptic vesicles, respectively, in both mouse lines.ResultsWhole-cell recordings from postsynaptic horizontal cells of the two mouse lines showed that the presence of Bassoon (and a ribbon) enhanced the rate of exocytosis during tonic and evoked release by increasing synaptic vesicle pool size and replenishment rate, while at the same time slowing synaptic vesicle release. Furthermore, the number of Ca(v)1.4 channels and synaptic vesicles was significantly higher at wild-type than at Bassoon mutant synaptic sites.ConclusionThe results of our study demonstrate that glutamate release from cone photoreceptor terminals can occur independent of a synaptic ribbon, but seems restricted to active zones, and they show the importance of a the synaptic ribbon in sustained and spatially and temporally synchronized neurotransmitter release.