據(jù)9月16日Nature雜志網(wǎng)絡(luò)版的一篇研究報告,，耶魯大學(xué)的研究人員發(fā)現(xiàn),，大腦皮層不同神經(jīng)元混合形成縱向柱狀排列的分子機制。
大腦皮層進行信息處理依賴于一組縱向柱狀排列的神經(jīng)元,。一旦這些神經(jīng)元的數(shù)量和種類發(fā)生錯誤,，則會引起認知能力障礙，如導(dǎo)致自閉癥和智力遲鈍等,。但一直以來,，科學(xué)家對這種柱狀排列的混合神經(jīng)元的分子機制不甚了解。
在這篇由Pasko Rakic教授主持的課題組中,，研究人員利用先進的分子技術(shù)表明,，在神經(jīng)細胞遷移過程中,，柱狀排列的混合神經(jīng)元依賴于兩種基因——A-型Eph受體以及ephrin-As配體基因的表達水平，ephrin-As配體結(jié)合到A-型Eph受體上,。研究發(fā)現(xiàn),，當小鼠缺少配體或受體的情況下，神經(jīng)細胞將不能橫向遷移到柱狀的合適位置,。
據(jù)第一作者Masaaki Torii介紹,，他發(fā)現(xiàn)這兩種基因所控制的神經(jīng)細胞的橫向遷移在正常的大腦皮質(zhì)的發(fā)育過程中起著總要的作用,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 16 September 2009 | doi:10.1038/nature08362
Integration of neuronal clones in the radial cortical columns by EphA and ephrin-A signalling
Masaaki Torii1,2, Kazue Hashimoto-Torii1, Pat Levitt2 & Pasko Rakic1
1 Department of Neurobiology and Kavli Institute for Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06510, USA
2 Zilkha Neurogenetic Institute and Department of Cell and Neurobiology, Keck School of Medicine of USC, Los Angeles, California 90089, USA
The cerebral cortex is a laminated sheet of neurons composed of the arrays of intersecting radial columns1, 2, 3. During development, excitatory projection neurons originating from the proliferative units at the ventricular surface of the embryonic cerebral vesicles migrate along elongated radial glial fibres4 to form a cellular infrastructure of radial (vertical) ontogenetic columns in the overlaying cortical plate5. However, a subpopulation of these clonally related neurons also undergoes a short lateral shift and transfers from their parental to the neighbouring radial glial fibres6, and intermixes with neurons originating from neighbouring proliferative units5, 7. This columnar organization acts as the primary information processing unit in the cortex1, 8, 9. The molecular mechanisms, role and significance of this lateral dispersion for cortical development are not understood. Here we show that an Eph receptor A (EphA) and ephrin A (Efna) signalling-dependent shift in the allocation of clonally related neurons is essential for the proper assembly of cortical columns. In contrast to the relatively uniform labelling of the developing cortical plate by various molecular markers and retrograde tracers in wild-type mice, we found alternating labelling of columnar compartments in Efna knockout mice that are caused by impaired lateral dispersion of migrating neurons rather than by altered cell production or death. Furthermore, in utero electroporation showed that lateral dispersion depends on the expression levels of EphAs and ephrin-As during neuronal migration. This so far unrecognized mechanism for lateral neuronal dispersion seems to be essential for the proper intermixing of neuronal types in the cortical columns, which, when disrupted, might contribute to neuropsychiatric disorders associated with abnormal columnar organization8, 10.
