Processing of reelin by embryonic neurons is important for function in tissue but not in dissociated cultured neurons
Processing of reelin by embryonic neurons is important for function in tissue but not in dissociated cultured neurons
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DOI：
10.1523/jneurosci.0023-07.2007
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发表时间：
2007-04-18
影响因子：
5.3
通讯作者：
Goffinet, Andre M.
中科院分区：
文献类型：
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作者：
Jossin, Yves;Gui, Lanrun;Goffinet, Andre M.
Reelin 是 reeler 突变小鼠中存在缺陷的蛋白质，在大脑发育过程中发挥着关键作用。 Reelin 在两个位点进行蛋白水解加工，中心片段模拟体外功能。在这里，我们证明加工在体内具有重要的功能，这是我们之前的研究无法解决的问题。针对中央 Reelin 的新型单克隆抗体可阻断其与脂蛋白受体的结合，并扰乱体外皮质发育，证实了在组织和体液中检测到的中央片段的重要性。当 Reelin 与培养物中的胚胎神经元或其上清液一起孵育时，就会发生加工，但金属蛋白酶阻断剂对加工的抑制不会阻止神经元中的 Reelin 信号传导。此外，神经元内化类似的全长或中央 Reelin。相反，抑制处理会阻止信号传导并扰乱培养的胚胎脑切片中的皮质发育。此外，在体内，中枢Reelin的浓度在受体缺陷组织中显着且选择性地增加，表明其在与受体结合和内化后特异性下调。我们提出，组织中需要通过末端迁移神经元进行处理（其中 Reelin 可能锚定到细胞外基质）以释放局部扩散并向靶细胞发出信号的中心片段，而在体外，所有 Reelin 形式都可以不加区别地访问细胞，因此信号传导不需要裂解。
Reelin, the protein defective in reeler mutant mice, plays a key role during brain development. Reelin is processed proteolytically at two sites, and the central fragment mimics function in vitro.Here, we show that processing is functionally important in vivo, a question that could not be addressed in our previous study. New monoclonal antibodies directed against central Reelin block its binding to lipoprotein receptors and perturb cortical development in vitro, confirming the importance of the central fragment that is detected in tissue and body fluids. Processing occurs when Reelin is incubated with embryonic neurons in culture or with their supernatant, but inhibition of processing by a metalloproteinase blocker does not prevent Reelin signaling in neurons. Furthermore, neurons internalize similarly full-length or central Reelin. In contrast, inhibition of processing prevents signaling and perturbs cortical development in cultured embryonic brain slices. Moreover, in vivo, the concentration of central Reelin is dramatically and selectively increased in receptor-deficient tissue, suggesting its specific downregulation after binding to receptors and internalization. We propose that processing by end-migration neurons is required in tissue ( where Reelin is likely anchored to the extracellular matrix) to release the central fragment that diffuses locally and signals to target cells, whereas, in vitro, all Reelin forms have indiscriminate access to cells, so that cleavage is not necessary for signaling.