Human CLOCK enhances cognitive flexibility by altering cortical excitatory neuron function

A BAC containing human CLOCK gene with flanking regulatory region was transferred to mice. The humazied (HU) mice outperformed wildtype (WT) in a reversal learning task, and hence suggested enhanced cognitive flexibility in HU mice. IHC of frontal cortex suggested that the enhanced cognitive flexibility in HU mice might result from the increased neuronal density, dendritic arborization, and spine density. In order to determine the molecular mechanism, we conducted single-nuclei RNA-seq on frontal cortex from postnatal 7 day (P7) and P56 mice. In the excitatory neuron, genes that upregulated in HU mice were enriched for dendritic growth (e.g. Tenm2 and Flrt2), spine formation (e.g. Cntn5 and Sorcs2), and energy metabolism (e.g. Suclg1 and Cox8a).将携带人源CLOCK基因及其侧翼调控区域的细菌人工染色体（Bacterial Artificial Chromosome, BAC）转入小鼠体内。人源化（HU）小鼠在反转学习任务中的表现优于野生型（WT）小鼠，提示HU小鼠的认知灵活性得到增强。对前额叶皮层开展免疫组织化学（Immunohistochemistry, IHC）检测结果显示，HU小鼠认知灵活性的提升可能与其神经元密度、树突分支以及突触棘密度的增加相关。为探明其分子机制，我们对出生后7天（P7）及出生后56天（P56）小鼠的前额叶皮层进行了单细胞核RNA测序（single-nuclei RNA-seq）。在兴奋性神经元中，HU小鼠体内上调的基因显著富集于树突生长（如Tenm2、Flrt2）、突触棘形成（如Cntn5、Sorcs2）以及能量代谢（如Suclg1、Cox8a）相关通路。