Hurni Nicolas, Kolodziejczak Marta, Tomasello Ugo, Badia Joan, Jacobshagen Moritz, Prados Julien, Dayer Alexandre
Department of Psychiatry, University of Geneva Medical School, CH-1211 Geneva 4, Switzerland.
Department of Basic Neurosciences, University of Geneva Medical School, CH-1211 Geneva 4, Switzerland.
Cereb Cortex. 2017 May 1;27(5):3052-3063. doi: 10.1093/cercor/bhx059.
Neocortical microcircuits are built during development and require the coordinated assembly of excitatory glutamatergic projection neurons (PNs) into functional networks. Neuronal migration is an essential step in this process. In addition to cell-intrinsic mechanisms, external cues including neurotransmitters regulate cortical neuron migration, suggesting that early activity could influence this process. Here, we aimed to investigate the role of cell-intrinsic activity in migrating PNs in vivo using a designer receptor exclusively activated by a designer drug (DREADD) chemogenetic approach. In utero electroporation was used to specifically express the human M3 muscarinic cholinergic Gq-coupled receptor (hM3Dq) in PNs and calcium activity, migratory dynamics, gene expression, and laminar positioning of PNs were assessed following embryonic DREADD activation. We found that transient embryonic DREADD activation induced premature branching and transcriptional changes in migrating PNs leading to a persistent laminar mispositioning of superficial layer PNs into deep cortical layers without affecting expression of layer-specific molecular identity markers. In addition, live imaging approaches indicated that embryonic DREADD activation increased calcium transients in migrating PNs and altered their migratory dynamics by increasing their pausing time. Taken together, these results support the idea that increased cell-intrinsic activity during migration acts as a stop signal for migrating cortical PNs.
新皮质微电路在发育过程中形成，需要将兴奋性谷氨酸能投射神经元（PNs）协调组装成功能网络。神经元迁移是这一过程中的关键步骤。除了细胞内在机制外，包括神经递质在内的外部信号也会调节皮质神经元迁移，这表明早期活动可能会影响这一过程。在这里，我们旨在使用一种仅由设计药物激活的设计受体（DREADD）化学遗传学方法，研究体内迁移的PNs中细胞内在活动的作用。通过子宫内电穿孔在PNs中特异性表达人M3毒蕈碱胆碱能Gq偶联受体（hM3Dq），并在胚胎期DREADD激活后评估PNs的钙活性、迁移动力学、基因表达和层定位。我们发现，短暂的胚胎期DREADD激活会诱导迁移的PNs过早分支和转录变化，导致表层PNs持续错层定位到深层皮质层，而不影响层特异性分子身份标记的表达。此外，实时成像方法表明，胚胎期DREADD激活会增加迁移的PNs中的钙瞬变，并通过增加其暂停时间改变其迁移动力学。综上所述，这些结果支持了这样一种观点，即迁移过程中细胞内在活动的增加对迁移的皮质PNs起到了停止信号的作用。
