Immunocytochemical Analysis of Axonal Outgrowth in Synaptotagmin Mutations
Immunocytochemical Analysis of Axonal Outgrowth in Synaptotagmin Mutations
复制标题
突触结合蛋白突变中轴突生长的免疫细胞化学分析
作者：
J. Littleton;Linda M. Upton;A. Kania
摘要：Synaptotagmin是一种突触囊泡特异性蛋白，在体外结合钙和磷脂，是钙调节的突触囊泡与突触前膜融合所必需的。我们研究了突触联合蛋白在轴突生长中可能的需求，通过跟踪突触联合蛋白基因缺失的果蝇胚胎的神经元发育。我们发现在野生型胚胎突触形成之前，synaptotagmin在轴突和生长锥中大量表达。利用synaptotagmin囊内结构域的抗体标记活胚胎，我们证明含有synaptotagmin的囊泡群体在轴突发生过程中积极地进行胞外分泌。我们使用免疫细胞化学技术检测了轴突蛋白fasiclin II、突触前膜蛋白syntaxin和突触囊泡蛋白半胱氨酸弦蛋白在突触塔蛋白缺失突变中的分布。这些蛋白在野生型和synaptotagmin突变胚胎中的分布是相似的，这表明在中枢神经系统或PNS中，synaptotagmin不是轴突发生所必需的。基于这些发现，我们认为轴突生长过程中囊泡介导的膜扩张的分子机制与神经递质释放过程中突触囊泡融合所需的分子机制不同。
Abstract: Synaptotagmin is a synaptic vesicle specific protein that binds calcium and phospholipids in vitro and is required for calcium‐regulated fusion of synaptic vesicles with the presynaptic membrane. We have examined the possible requirement for synaptotagmin in axonal outgrowth by following neuronal development in Drosophila embryos deficient for the synaptotagmin gene. We find that synaptotagmin is expressed abundantly in axons and growth cones before synapse formation in wild‐type embryos. Using antibodies to the intravesicular domain of synaptotagmin to label live embryos, we demonstrate that vesicle populations containing synaptotagmin actively undergo exocytosis during axonogenesis. We have used immunocytochemical techniques to examine the distribution of the axonal protein Fasciclin II, the presynaptic membrane protein syntaxin, and the synaptic vesicle protein cysteine string protein, in synaptotagmin null mutations. The distribution of these proteins is similar in wild‐type and synaptotagmin mutant embryos, suggesting that synaptotagmin is not required for axonogenesis in the CNS or PNS. Based on these findings, we suggest that the molecular mechanisms underlying vesicular‐mediated membrane expansion during axonal outgrowth are distinct from those required for synaptic vesicle fusion during neurotransmitter release.
影响因子：
4.6
作者：
J. Littleton;H. Bellen;M. Perin
通讯作者：
J. Littleton;H. Bellen;M. Perin