Department of Brain Function, University of Fukui School of Medicine, 23-3 Shimo-aizuki, Matsuoka, Fukui, 910-1193, Japan.
Department of Physiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Nat Commun. 2018 May 9;9(1):1842. doi: 10.1038/s41467-018-04239-z.
In mammals, neural circuits are formed based on a genetic program and further refined by neuronal activity during the neonatal period. We report that in the mouse olfactory system, the glomerular map is not merely refined but newly connected to second-order neurons by odorant-receptor-derived neuronal activity. Here, we analyzed a pair of molecules, Sema7A, expressed in olfactory sensory neurons (OSNs) in an activity-dependent manner, and PlxnC1, localized to dendrites of mitral/tufted (M/T) cells in the first week after birth. In Sema7A or PlxnC1 knockout (KO) mice, initiation of synapse formation and dendrite selection of M/T cells were perturbed. Reconstitution and rescue experiments demonstrated that Sema7A-PlxnC1 interaction is essential to form the post-synaptic assembly. Pharmacological blocking experiments indicated that synaptic transmission triggers primary dendrite selection by synaptic competition. We conclude that Sema7A signaling is key to inducing activity-dependent post-synapse events and dendrite selection in M/T-cells during the neonatal period.
在哺乳动物中，神经回路是基于遗传程序形成的，并在新生儿期通过神经元活动进一步细化。我们报告说，在小鼠嗅觉系统中，嗅球图谱不仅得到了细化，而且通过气味受体衍生的神经元活动与二级神经元新连接。在这里，我们分析了一对分子，Sema7A，以依赖于活动的方式表达在嗅觉感觉神经元（OSN）中，PlxnC1 定位于出生后第一周的僧帽/锥形（M/T）细胞的树突上。在 Sema7A 或 PlxnC1 敲除（KO）小鼠中，M/T 细胞的突触形成和树突选择的起始受到干扰。重建和拯救实验表明，Sema7A-PlxnC1 相互作用对于形成突触后装配是必不可少的。药理阻断实验表明，突触传递通过突触竞争触发初级树突选择。我们得出结论，Sema7A 信号是诱导新生儿期 M/T 细胞中活性依赖性突触后事件和树突选择的关键。
