Abnormal Neuronal Migration Changes the Fate of Developing Neurons in the Postnatal Olfactory Bulb
Abnormal Neuronal Migration Changes the Fate of Developing Neurons in the Postnatal Olfactory Bulb
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DOI：
10.1523/jneurosci.6716-10.2011
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发表时间：
2011-05-18
影响因子：
5.3
通讯作者：
Lledo, Pierre-Marie
中科院分区：
文献类型：
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作者：
Belvindrah, Richard;Nissant, Antoine;Lledo, Pierre-Marie
神经元前体不断整合到成年嗅球(OB)中。这些前体细胞绝大多数起源于脑室下区，并沿着吻侧迁移流(RMS)向OB迁移。这个过程被称为出生后神经发生，是由复杂的途径导致的，依赖于细胞自主因素和当地环境提供的外部调节。利用出生后小鼠的电穿孔技术，用绿色荧光蛋白(GFP)标记神经元前体，并用短发夹状(Sh)RNA降低双皮质酮(DCX)的表达水平，我们研究了迁移障碍对出生后形成的神经元命运的影响。首先，我们证明了DCX shRNA质粒的电穿孔有效地下调了DCX的表达，并破坏了细胞沿RMS的迁移。其次，我们发现了错位的异常迁移细胞，表现出极性和方向性的缺陷。第三，在电穿孔(DPE)后5-7天进行的膜片钳记录显示，电压依赖性Na(+)通道密度增加，对GABA(A)受体激动剂的反应增强。在以后的时间点(即12个和30个DPE)，大多数DCX shRNA(+)细胞在OB的中心发育，并表现出异常的树突长度和分支。另外的分析显示，错位的神经元上形成了GABA能和谷氨酸能突触输入。最后，通过计数GFP(+)/calretinin(+)新生神经元的比例来量化命运决定，发现DCX shRNA(+)细胞尽管位置不成熟，但仍获得了成熟的表型。我们的结论是，在出生后神经发生的早期阶段改变迁移速度深刻地改变了神经元成熟的紧密协调步骤，并揭示了微环境对控制出生后前脑神经元发育的影响。
Neuronal precursors are continuously integrated into the adult olfactory bulb (OB). The vast majority of these precursor cells originates from the subventricular zone and migrates along the rostral migratory stream (RMS) en route to the OB. This process, called postnatal neurogenesis, results from intricate pathways depending both on cell-autonomous factors and extrinsic regulation provided by the local environment. Using electroporation in postnatal mice to label neuronal precursors with green fluorescent protein (GFP) and to reduce the expression levels of doublecortin (DCX) with short-hairpin (Sh) RNA, we investigated the consequences of impairing migration on the fate of postnatal-formed neurons. First, we showed that electroporation of Dcx ShRNA plasmid efficiently knocks down the expression of DCX and disrupts cells migration along the RMS. Second, we found misplaced anomalous migrating cells that displayed defects in polarity and directionality. Third, patch-clamp recordings performed at 5-7 days post-electroporation (dpe) revealed increased density of voltage-dependent Na(+) channels and enhanced responsiveness to GABA(A) receptor agonist. At later time points (i.e., 12 and 30 dpe), most of the Dcx ShRNA(+) cells developed in the core of the OB and displayed aberrant dendritic length and branching. Additional analysis revealed the formation of GABAergic and glutamatergic synaptic inputs on the mispositioned neurons. Finally, quantifying fate determination by numbering the proportion of GFP(+)/calretinin(+) newborn neurons revealed that Dcx ShRNA(+) cells acquire mature phenotype despite their immature location. We conclude that altering the pace of migration at early stages of postnatal neurogenesis profoundly modifies the tightly orchestrated steps of neuronal maturation, and unveils the influence of microenvironment on controlling neuronal development in the postnatal forebrain.