Bulk membrane retrieval in the synaptic terminal of retinal bipolar cells
Bulk membrane retrieval in the synaptic terminal of retinal bipolar cells
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DOI：
10.1523/jneurosci.23-04-01329.2003
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发表时间：
2003-02-15
影响因子：
5.3
通讯作者：
Lagnado, L
中科院分区：
文献类型：
--
作者：
Holt, M;Cooke, A;Lagnado, L
大量的突触膜摄取的机制仍然不清楚，虽然胞吐的突触囊泡的补偿膜检索到小泡和大池或空泡。我们研究了视网膜双极细胞突触前末梢的批量检索。荧光成像的膜染料FM 1 -43表明，Ca 2+触发的胞吐作用后，内吞成小泡和较大的空泡，可以选择性地标记使用大荧光葡聚糖。用细胞松弛素D或latrunculin B破坏肌动蛋白丝抑制空泡的形成和运输，但胞吐和胞吞继续以正常速率进行。批量回收与肌动蛋白网络的重塑有关，这两个过程都被2-（4-吗啉基）-8-苯基-4H-1-苯并吡喃-4-酮（磷脂酰肌醇3-激酶（PI 3-激酶）的抑制剂）抑制。因此，由Ca 2+和PI 3-激酶调节的F-肌动蛋白动力学在该突触的补偿性内吞中发挥了重要作用，但这种作用仅限于体膜摄取。电容测量表明，快速内吞和重新填充的快速释放池的囊泡不依赖于F-肌动蛋白或PI 3-激酶活性。在这个突触大量膜检索的基本属性是非常相似的巨胞饮在非神经细胞中描述。批量检索没有发挥重要作用，在维持刺激过程中维持囊泡周期，但我们认为，它可能发挥作用，在这个突触终端的结构可塑性。
The mechanism of bulk membrane uptake at the synapse remains poorly defined, although exocytosis of synaptic vesicles is followed by compensatory membrane retrieval into both small vesicles and large cisternas or vacuoles. We investigated bulk retrieval in the presynaptic terminal of retinal bipolar cells. Fluorescence imaging of the membrane dye FM1-43 indicated that Ca2+-triggered exocytosis was followed by endocytosis into small vesicles and larger vacuoles that could be selectively labeled using large fluorescent dextrans. Disruption of actin filaments with cytochalasin D or latrunculin B inhibited the formation and transport of vacuoles, but exocytosis and endocytosis continued at normal rates. Bulk retrieval was linked to remodeling of the actin network, and both processes were inhibited by 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, an inhibitor of phosphatidylinositol 3-kinase (PI3-kinase). The regulation of F-actin dynamics by Ca2+ and PI3-kinase therefore played an important role in compensatory endocytosis at this synapse, but this role was confined to bulk membrane uptake. Capacitance measurements demonstrated that fast endocytosis and refilling of the rapidly releasable pool of vesicles were not dependent on F-actin or PI3-kinase activity. The basic properties of bulk membrane retrieval at this synapse were very similar to macropinocytosis described in non-neural cells. Bulk retrieval did not play an essential role in maintaining the vesicle cycle during maintained stimulation, but we suggest that it may play a role in the structural plasticity of this synaptic terminal.