NEURONAL COMPARTMENTS AND AXONAL-TRANSPORT OF SYNAPSIN-I
NEURONAL COMPARTMENTS AND AXONAL-TRANSPORT OF SYNAPSIN-I
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DOI：
10.1007/bf02780556
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发表时间：
1992-06-01
影响因子：
5.1
通讯作者：
PETRUCCI, TC
中科院分区：
文献类型：
--
作者：
PAGGI, P;PETRUCCI, TC
对突触素I在小鼠视网膜神经节细胞中的转运动力学和翻译后修饰进行了研究，以深入了解形成轴突及其终末结构和功能差异的可能因素。突触素I是一种神经元磷酸蛋白，与突触前终末的小突触小泡和细胞骨架元件有关，被认为参与调节神经递质的释放。突触素I在体外的磷酸化状态调节其与突触小泡和细胞骨架成分(包括微管和微丝)的相互作用。在这里，我们提出了第一个证据，在小鼠视网膜神经节细胞中，大多数突触素i与细胞基质蛋白一起沿轴突向下运输，其速度与轴突运输的慢组分b相同，并且在头部和尾部区域都被磷酸化。此外，我们的数据表明，在突触素I到达神经末梢后，各种磷酸化的突触素I分子的相对比例发生了变化，这些变化导致了磷的总体含量的下降。这些结果与这样的假设一致，即在体内，突触素I沿着轴突的磷酸化阻止了密集网络的形成，这可能会损害细胞器的运动。另一方面，神经末梢突触蛋白I的去磷酸化可能调节小突触小泡的聚集，并通过控制小突触小泡的可用于胞吐来调节神经递质的释放。
Studies on the transport kinetics and the posttranslational modification of synapsin I in mouse retinal ganglion cells were performed to obtain an insight into the possible factors involved in forming the structural and functional differences between the axon and its terminals. Synapsin I, a neuronal phosphoprotein associated with small synaptic vesicles and cytoskeletal elements at the presynaptic terminals, is thought to be involved in modulating neurotransmitter release. The state of phosphorylation of synapsin I in vitro regulates its interaction with both synaptic vesicles and cytoskeletal components, including microtubules and microfilaments. Here we present the first evidence that in the mouse retinal ganglion cells most synapsin I is transported down the axon, together with the cytomatrix proteins, at the same rate as the slow component b of axonal transport, and is phosphorylated at both the head and tail regions. In addition, our data suggest that, after synapsin I has reached the nerve endings, the relative proportions of variously phosphorylated synapsin I molecules change, and that these changes lead to a decrease in the overall content of phosphorus. These results are consistent with the hypothesis that, in vivo, the phosphorylation of synapsin I along the axon prevents the formation of a dense network that could impair organelle movement. On the other hand, the dephosphorylation of synapsin I at the nerve endings may regulate the clustering of small synaptic vesicles and modulate neurotransmitter release by controlling the availability of small synaptic vesicles for exocytosis.