Regulation of Axon Initial Segment Diameter by COUP-TFI Fine-tunes Action Potential Generation.

Xuanyuan Wu, Haixiang Li, Jiechang Huang, Mengqi Xu, Cheng Xiao, Shuijin He

Neuroscience bulletin 2022 May

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The axon initial segment (AIS) is a specialized structure that controls neuronal excitability via action potential (AP) generation. Currently, AIS plasticity with regard to changes in length and location in response to neural activity has been extensively investigated, but how AIS diameter is regulated remains elusive. Here we report that COUP-TFI (chicken ovalbumin upstream promotor-transcription factor 1) is an essential regulator of AIS diameter in both developing and adult mouse neocortex. Either embryonic or adult ablation of COUP-TFI results in reduced AIS diameter and impaired AP generation. Although COUP-TFI ablations in sparse single neurons and in populations of neurons have similar impacts on AIS diameter and AP generation, they strengthen and weaken, respectively, the receiving spontaneous network in mutant neurons. In contrast, overexpression of COUP-TFI in sparse single neurons increases the AIS diameter and facilitates AP generation, but decreases the receiving spontaneous network. Our findings demonstrate that COUP-TFI is indispensable for both the expansion and maintenance of AIS diameter and that AIS diameter fine-tunes action potential generation and synaptic inputs in mammalian cortical neurons. © 2021. Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences.

Citation

Xuanyuan Wu, Haixiang Li, Jiechang Huang, Mengqi Xu, Cheng Xiao, Shuijin He. Regulation of Axon Initial Segment Diameter by COUP-TFI Fine-tunes Action Potential Generation. Neuroscience bulletin. 2022 May;38(5):505-518