Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.
Institute of Structural and Molecular Biology, Birkbeck and University College London, London WC1E 7HX, United Kingdom.
Proc Natl Acad Sci U S A. 2020 Sep 22;117(38):23527-23538. doi: 10.1073/pnas.2003662117. Epub 2020 Sep 9.
Clathrin light chain (CLC) subunits in vertebrates are encoded by paralogous genes and , and both gene products are alternatively spliced in neurons. To understand how this CLC diversity influences neuronal clathrin function, we characterized the biophysical properties of clathrin comprising individual CLC variants for correlation with neuronal phenotypes of mice lacking either CLC-encoding gene. CLC splice variants differentially influenced clathrin knee conformation within assemblies, and clathrin with neuronal CLC mixtures was more effective in membrane deformation than clathrin with single neuronal isoforms nCLCa or nCLCb. Correspondingly, electrophysiological recordings revealed that neurons from mice lacking nCLCa or nCLCb were both defective in synaptic vesicle replenishment. Mice with only nCLCb had a reduced synaptic vesicle pool and impaired neurotransmission compared to WT mice, while nCLCa-only mice had increased synaptic vesicle numbers, restoring normal neurotransmission. These findings highlight differences between the CLC isoforms and show that isoform mixing influences tissue-specific clathrin activity in neurons, which requires their functional balance.
脊椎动物的网格蛋白轻链 (CLC) 亚基由同源基因 和 编码，这两种基因产物在神经元中都可进行选择性剪接。为了了解这种 CLC 多样性如何影响神经元网格蛋白的功能，我们对包含单个 CLC 变体的网格蛋白的物理特性进行了表征，以便与缺乏任一 CLC 编码基因的小鼠的神经元表型相关联。CLC 剪接变体在组装体中对网格蛋白膝部构象的影响不同，并且具有神经元 CLC 混合物的网格蛋白比具有单个神经元同工型 nCLCa 或 nCLCb 的网格蛋白更有效地促进膜变形。相应地，电生理记录显示，缺乏 nCLCa 或 nCLCb 的小鼠的突触小泡再填充均存在缺陷。与 WT 小鼠相比，仅缺乏 nCLCb 的小鼠的突触小泡池减少，神经传递受损，而仅缺乏 nCLCa 的小鼠的突触小泡数量增加，恢复正常的神经传递。这些发现突出了 CLC 同工型之间的差异，并表明同工型混合会影响神经元中组织特异性网格蛋白的活性，这需要它们的功能平衡。
