γ-secretase and metalloproteinase activity regulate the distribution of endoplasmic reticulum to hippocampal neuron dendritic spines
γ-secretase and metalloproteinase activity regulate the distribution of endoplasmic reticulum to hippocampal neuron dendritic spines
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DOI：
10.1096/fj.07-103903
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发表时间：
2008-08-01
期刊：
影响因子：
4.8
通讯作者：
Toresson, Hakan
中科院分区：
文献类型：
--
作者：
Ng, Ai Na;Toresson, Hakan
神经元内质网（ER）参与脑内许多生理和病理过程。海马神经元上的树突棘的子集含有可能有助于突触特异性细胞内信号传导的ER。ER在脊柱中的分布是动态的，但缺乏对其调控机制的了解。在活细胞成像实验中，我们现在发现，培养的海马神经元在佛波酯处理后迅速失去了ER。通过抑制γ-分泌酶（2 μ M的DAPT）和金属蛋白酶（4 μ M的TAPI-0和GM 6001）活性来减少ER损失。蛋白激酶C的抑制也通过阻止ER从棘退出而减少ER的损失。此外，γ-分泌酶和金属蛋白酶的抑制，在佛波酯的情况下，引发了脊柱ER含量的急剧增加。金属蛋白酶和γ-分泌酶切割几种跨膜蛋白。已知许多这些底物定位于粘附连接，这是一种与棘ER相互作用的结构特化。一个有趣的可能性是，因此，ER内容在棘可能是调节蛋白水解活性影响adherens连接。我们的数据表明，这两个蛋白水解活性在调节细胞超微结构的动态方面，这是一个迄今为止未知的作用，细胞内钙稳态和几个细胞内信号转导通路，这是潜在的重要。
The neuronal endoplasmic reticulum (ER) contributes to many physiological and pathological processes in the brain. A subset of dendritic spines on hippocampal neurons contains ER that may contribute to synapse-specific intracellular signaling. Distribution of ER to spines is dynamic, but knowledge of the regulatory mechanisms is lacking. In live cell imaging experiments we now show that cultured hippocampal neurons rapidly lost ER from spines after phorbol ester treatment. ER loss was reduced by inhibiting gamma-secretase (DAPT at 2 mu M) and metalloproteinase (TAPI-0 and GM6001 at 4 mu M) activity. Inhibition of protein kinase C also diminished loss of ER by preventing exit of ER from spines. Furthermore, gamma-secretase and metalloproteinase inhibition, in the absence of phorbol ester, triggered a dramatic increase in spine ER content. Metalloproteinases and gamma-secretase cleave several transmembrane proteins. Many of these substrates are known to localize to adherens junctions, a structural specialization with which spine ER interacts. One interesting possibility is thus that ER content within spines may be regulated by proteolytic activity affecting adherens junctions. Our data demonstrate a hitherto unknown role for these two proteolytic activities in regulating dynamic aspects of cellular ultrastructure, which is potentially important for cellular calcium homeostasis and several intracellular signaling pathways.