Cell-Specific Loss of SNAP25 from Cortical Projection Neurons Allows Normal Development but Causes Subsequent Neurodegeneration
Cell-Specific Loss of SNAP25 from Cortical Projection Neurons Allows Normal Development but Causes Subsequent Neurodegeneration
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DOI：
10.1093/cercor/bhy127
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发表时间：
2019-05-01
期刊：
影响因子：
3.7
通讯作者：
Molnar, Zoltan
中科院分区：
文献类型：
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作者：
Hoerder-Suabedissen, Anna;Korrell, Kim V.;Molnar, Zoltan
突触体相关蛋白25 kDa（SNAP 25）是SNARE复合物调节突触囊泡融合的重要组成部分。SNAP 25缺陷与多种认知障碍有关。我们通过产生在外显子5a/5 b侧翼具有LoxP位点的转基因小鼠（B6-Snap 25 tm 3 mcw（Snap 25-flox）），从选定的神经元群体中消除SNAP 25。在Cre重组酶存在下，将Snap 25-flox重组为截短的转录物。诱发的突触囊泡释放在Snap 25条件性敲除（cKO）神经元中严重减少，如通过突触囊泡融合的活细胞成像和培养的海马神经元中的全细胞膜片钳记录所示。我们研究了体内皮质投射神经元亚群（L5-Rbp 4-Cre; L 6-Ntsr 1-Cre; L 6 b-Drd 1a-Cre）中的Snap 25 cKO。cKO神经元产生正常的轴突投射，但轴突没有得到适当的维持，显示出肿胀、碎裂和最终完全缺失的迹象。退化的发生和进展取决于神经元类型，L5细胞显示出最早和最严重的轴突损失。超微结构检查显示cKO神经突含有自噬体/溶酶体样结构。炎症标志物如Iba 1和脂褐素仅在成人cKO皮质中增加。Snap 25 cKO可以提供一个模型来研究遗传相互作用与环境的影响，在几种疾病。
Synaptosomal associated protein 25 kDa (SNAP25) is an essential component of the SNARE complex regulating synaptic vesicle fusion. SNAP25 deficiency has been implicated in a variety of cognitive disorders. We ablated SNAP25 from selected neuronal populations by generating a transgenic mouse (B6-Snap25tm3mcw (Snap25-flox)) with LoxP sites flanking exon5a/5b. In the presence of Cre-recombinase, Snap25-flox is recombined to a truncated transcript. Evoked synaptic vesicle release is severely reduced in Snap25 conditional knockout (cKO) neurons as shown by live cell imaging of synaptic vesicle fusion and whole cell patch clamp recordings in cultured hippocampal neurons. We studied Snap25 cKO in subsets of cortical projection neurons in vivo (L5-Rbp4-Cre; L6-Ntsr1-Cre; L6b-Drd1a-Cre). cKO neurons develop normal axonal projections, but axons are not maintained appropriately, showing signs of swelling, fragmentation and eventually complete absence. Onset and progression of degeneration are dependent on the neuron type, with L5 cells showing the earliest and most severe axonal loss. Ultrastructural examination revealed that cKO neurites contain autophagosome/lysosome-like structures. Markers of inflammation such as Iba1 and lipofuscin are increased only in adult cKO cortex. Snap25 cKO can provide a model to study genetic interactions with environmental influences in several disorders.