Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Piscataway, NJ 08854, United States of America. Graduate Program in Biomedical Engineering, Rutgers University, 599 Taylor Road, Piscataway, NJ 08854, United States of America.
J Neural Eng. 2018 Feb;15(1):016020. doi: 10.1088/1741-2552/aa976a.
This study investigates the effect that overexpression of cytosolic PSD-95 interactor (cypin), a regulator of synaptic PSD-95 protein localization and a core regulator of dendrite branching, exerts on the electrical activity of rat hippocampal neurons and networks.
We cultured rat hippocampal neurons and used lipid-mediated transfection and lentiviral gene transfer to achieve high levels of cypin or cypin mutant (cypinΔPDZ; PSD-95 non-binding) expression cellularly and network-wide, respectively.
Our analysis revealed that although overexpression of cypin and cypinΔPDZ increase dendrite numbers and decrease spine density, cypin and cypinΔPDZ distinctly regulate neuronal activity. At the single cell level, cypin promotes decreases in bursting activity while cypinΔPDZ reduces sEPSC frequency and further decreases bursting compared to cypin. At the network level, by using the Fano factor as a measure of spike count variability, cypin overexpression results in an increase in variability of spike count, and this effect is abolished when cypin cannot bind PSD-95. This variability is also dependent on baseline activity levels and on mean spike rate over time. Finally, our spike sorting data show that overexpression of cypin results in a more complex distribution of spike waveforms and that binding to PSD-95 is essential for this complexity.
Our data suggest that dendrite morphology does not play a major role in cypin action on electrical activity.
本研究探讨了细胞质突触后密度蛋白 95 相互作用蛋白（cypin）过表达对大鼠海马神经元和网络电活动的影响。cypin 是突触后密度蛋白 95 蛋白定位的调节剂，也是树突分支的核心调节剂。
我们培养大鼠海马神经元，分别采用脂质介导的转染和慢病毒基因转移，实现 cypin 或 cypin 突变体（不与 PSD-95 结合的 cypinΔPDZ）的高水平细胞内和全网络表达。
我们的分析表明，尽管 cypin 和 cypinΔPDZ 的过表达增加了树突数量并减少了棘突密度，但 cypin 和 cypinΔPDZ 明显调节神经元活性。在单细胞水平上，cypin 促进爆发活动减少，而 cypinΔPDZ 降低 sEPSC 频率，并进一步减少与 cypin 相比的爆发。在网络水平上，我们使用 Fano 因子作为尖峰计数变异性的度量，发现 cypin 过表达导致尖峰计数变异性增加，当 cypin 不能与 PSD-95 结合时，这种效应被消除。这种变异性还依赖于基线活动水平和随时间变化的平均尖峰率。最后，我们的尖峰分类数据表明，cypin 的过表达导致尖峰波形分布更加复杂，而与 PSD-95 的结合对于这种复杂性是必不可少的。
我们的数据表明，树突形态在 cypin 对电活动的作用中不起主要作用。
