Numb deficiency in cerebellar Purkinje cells impairs synaptic expression of metabotropic glutamate receptor and motor coordination
Numb deficiency in cerebellar Purkinje cells impairs synaptic expression of metabotropic glutamate receptor and motor coordination
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DOI：
10.1073/pnas.1512915112
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发表时间：
2015-11
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通讯作者：
Liang Zhou;Dong Yang;De-Juan Wang;Ya-Jun Xie;Jia-Huan Zhou;Lin Zhou;Hao Huang;Shuo Han;Chong‐Yu Shao;Hua-shun Li;J. J. Zhu-J.;M. Qiu;C. D. De Zeeuw;Ying Shen
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作者：
Liang Zhou;Dong Yang;De-Juan Wang;Ya-Jun Xie;Jia-Huan Zhou;Lin Zhou;Hao Huang;Shuo Han;Chong‐Yu Shao;Hua-shun Li;J. J. Zhu-J.;M. Qiu;C. D. De Zeeuw;Ying Shen
Numb蛋白通过与许多信号分子相互作用来控制细胞命运，这些信号分子对于维持中枢神经系统中的神经干细胞和神经元发育至关重要。然而，Numb的功能尚未在成熟神经元中研究。在这里，我们发现，在小脑浦肯野细胞中的Numb的删除导致运动学习的缺陷，这可以归因于突触代谢型谷氨酸1受体（mGlu 1）的水平降低。虽然Numb缺陷不会改变mGlu 1相关蛋白的表达和mGlu 1的活性依赖性可塑性，但它会抑制mGlu 1的细胞内运输。据我们所知，我们的工作是第一个证明Numb在成熟神经元中的重要功能。Numb蛋白首先在果蝇中被鉴定为细胞命运决定因子，已被证明促进哺乳动物神经突的发育，并在体外与网格蛋白包被的囊泡中的内吞受体共转运。然而，其在成熟神经元中的功能尚未阐明。在这里，我们表明，小脑浦肯野细胞（PC）表达高水平的Numb在成年期和有条件的删除Numb PC是足以损害运动协调，尽管维护一个正常的小脑细胞结构。Numb对代谢型谷氨酸1受体（mGlu 1）的内化和再循环具有重要作用。在条件性Numb基因敲除小鼠中观察到mGlu 1的显著降低和平行纤维-PC突触的长期抑制。事实上，在这些突变体中，由激动剂诱导的mGlu 1的贩运被显著抑制，但离子型谷氨酸受体亚基和mGlu 1相关蛋白的表达不受Numb丧失的影响。此外，短暂和持久形式的mGlu 1可塑性强烈诱导突变PC，这表明他们不需要mGlu 1贩运。总之，我们的数据表明，Numb是组成型表达和动态运输mGlu 1的调节器。
Significance Protein Numb controls cell fate by interacting with a number of signaling molecules, critical for maintaining neural stem cells and neuronal development in the central nervous system. However, the function of Numb has not been studied in mature neurons. Here, we found that deletion of Numb in cerebellar Purkinje cells causes deficits in motor learning, which can be ascribed to a reduced level of synaptic metabotropic glutamate 1 receptor (mGlu1). Although Numb deficiency does not alter the expression of mGlu1-associated proteins and activity-dependent plasticity of mGlu1, it inhibits intracellular trafficking of mGlu1. To our knowledge, our work is the first to demonstrate an important function of Numb in mature neurons. Protein Numb, first identified as a cell-fate determinant in Drosophila, has been shown to promote the development of neurites in mammals and to be cotransported with endocytic receptors in clathrin-coated vesicles in vitro. Nevertheless, its function in mature neurons has not yet been elucidated. Here we show that cerebellar Purkinje cells (PCs) express high levels of Numb during adulthood and that conditional deletion of Numb in PCs is sufficient to impair motor coordination despite maintenance of a normal cerebellar cyto-architecture. Numb proved to be critical for internalization and recycling of metabotropic glutamate 1 receptor (mGlu1) in PCs. A significant decrease of mGlu1 and an inhibition of long-term depression at the parallel fiber–PC synapse were observed in conditional Numb knockout mice. Indeed, the trafficking of mGlu1 induced by agonists was inhibited significantly in these mutants, but the expression of ionotropic glutamate receptor subunits and of mGlu1-associated proteins was not affected by the loss of Numb. Moreover, transient and persistent forms of mGlu1 plasticity were robustly induced in mutant PCs, suggesting that they do not require mGlu1 trafficking. Together, our data demonstrate that Numb is a regulator for constitutive expression and dynamic transport of mGlu1.