numb蛋白调节小脑浦肯野细胞突触可塑性和mGluR1受体的表达

The Marr-Albus-Ito law suggests that long-term depression (LTD) and long-term potentiation (LTP) alter the efficacy of synaptic transmission at parallel fiber-Purkinje cell synapses, which is the basis to cause the formation or extinction of memory trace during movement tasks. Clathrin-dependent endocytosis of AMPA receptors is the mechanism of LTD expression, but it has not been fully understood yet. Numb, an endocytoic protein, is shown to play important roles in neuronal development, but there is no report of its function in mature neurons. Our preliminary work first found that synaptic mGluR1 decreased upon the deletion of numb/numblike specifically in Purkinje cells, suggesting that numb may play multiple functions in Purkinje cells. In present project, we will utilized whole-cell patch-clamp, molecular biology, cellular biology and conditioned knock-out animals to study: 1) function of numb in Purkinje cell LTD; 2) modulation of numb on the expression of mGluR1 and its plasticity; 3) roles of numb in the development of Purkinje cell synapses; 4) the regulatory mechanisms of numb on sub-cellular expression of mGluR1. Our results will promote the understanding of functions of numb protein in mature neurons and vesicle trafficking during cerebellar synaptic plasticity, and give hints on the functions of Purkinje cells in the memory trace.

Marr-Albus-Ito定律提出，平行纤维-浦肯野细胞的长时程抑制（LTD）和长时程增强（LTP）改变突触传递效率，是运动记忆的基础。clathrin依赖的AMPA受体内吞是LTD基本机制，但过程不清楚。numb作为一个内吞蛋白在神经元发育中起作用，未见其在成熟神经元中功能的报道。我们前期研究发现条件性敲除浦肯野细胞的numb/numblike后，突触部位mGluR1表达下降，提示numb可能在浦肯野细胞中有多方面作用。本课题利用全细胞膜片钳记录、分子生物学、细胞生物学和基因敲除小鼠等技术，研究：1）numb在浦肯野细胞LTD的作用；2）numb在浦肯野细胞突触发育中的作用；3）numb调节mGluR1受体表达及其可塑性；4）numb调节mGluR1亚细胞表达的机制。课题研究成果将推动理解numb在成熟神经元和小脑突触可塑性中的作用，为研究浦肯野细胞在运动记忆中作用提供理论基础。

平行纤维-浦肯野细胞的长时程抑制（LTD）和长时程增强（LTP）改变突触传递效率，是运动记忆的基础。Clathrin依赖的AMPA受体内吞是LTD基本机制，但过程不清楚。Numb作为一个Clathrin结合的内吞蛋白调节神经元的发育，未见其在成熟神经元中功能的报道。本课题首次发现Numb在成熟神经元的重要作用：调节代谢性谷氨酸受体的突触表达，并影响小脑突触可塑性和运动行为。我们发现敲除Numb并不影响浦肯野细胞的树突生长和突触棘数目，提示之前的体外培养实验结果并不正确；缺失Numb特异性地下调了突触内代谢性谷氨酸受体mGlu1的表达，对于离子型谷氨酸受体没有影响；Numb通过干扰mGlu1的内吞和再循环过程影响mGlu1的表达；条件性敲除Numb造成了小脑浦肯野细胞长时程抑制的缺失和动物协调性运动行为的异常。我们的结果提示Numb可能通过影响mGlu1功能在自闭症中有重要作用。主要研究成果发表在国际著名杂志PNAS（Zhou et al., Proc Natl Acad Sci USA, 112:15474-15479, 2015），对运动和自闭症的相关机理有指导意义。本课题共完成SCI论文10篇，分别发表在分别发表在PNAS，J Neurosci（3篇），Front Mol Neurosci，Genes Dev，Neurochem Res，Mol Med Rep，Cerebellum和Neurochem Int，合计影响因子53。