disabled-1 functions cell autonomously during radial migration and cortical layering of pyramidal neurons
disabled-1 functions cell autonomously during radial migration and cortical layering of pyramidal neurons
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DOI：
10.1523/jneurosci.21-22-08798.2001
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发表时间：
2001-11-15
影响因子：
5.3
通讯作者：
Tan, SS
中科院分区：
文献类型：
--
作者：
Hammond, V;Howell, B;Tan, SS
遗传镶嵌为分析复杂的基因功能提供了极好的机会。由突变体和野生型细胞组成的嵌合体不仅提供了谱系特异性基因拯救的途径，而且还可以区分细胞自主基因功能和非细胞自主基因功能。使用野生型细胞的独立遗传标记，我们构建了Dab 1（+/+）Dab 1（-/-）嵌合体，目的是发现Dab 1在神经元迁移和皮质分层过程中的功能是否是细胞自主的。Dab 1（+/+）细胞在Dab 1（-/-）环境中能放射状迁移和柱状形成。大多数Dab 1（+/+）细胞分离到突变皮层的表面部分，形成多层的超皮层。神经元出生日期研究表明，超皮层神经元是正确分层的，尽管相邻的突变皮层神经元的顺序相反。使用锥体神经元标记物Emx 1的免疫细胞化学表明，上皮层中绝大多数Dab 1（+/+）神经元是Emx 1免疫反应性的。锥体细胞表型的确认证明了GABA免疫反应性Dab 1（+/+）细胞在上皮层的情况下。使用2 '3'-环核苷酸3 '-磷酸二酯酶进行的髓鞘染色显示，上皮层由次生白色物质支撑，从次生物质中粗纤维束似乎连接到下面的突变白色物质。Dab 1（+/+）细胞的存在未能挽救皮质层的倒置和Dab 1（+/+）细胞对边缘区的异常浸润。相反，突变体细胞并没有对相邻的野生型神经元施加突变体表型。这些结果表明，Dab 1功能细胞自主相对于放射状迁移和皮质分层的锥体神经元。
Genetic mosaics offer an excellent opportunity to analyze complex gene functions. Chimeras consisting of mutant and wildtype cells provide not only the avenue for lineage-specific gene rescue but can also distinguish cell-autonomous from non-cell-autonomous gene functions. Using an independent genetic marker for wild-type cells, we constructed Dab1(+/+) Dab1(-/-) chimeras with the aim of discovering whether or not the function of Dab1 during neuronal migration and cortical layering is cell autonomous. Dab1(+/+) cells were capable of radial migration and columnar formation in a Dab1(-/-) environment. Most Dab1(+/+) cells segregated to the superficial part of the mutant cortex, forming a multilayered supercortex. Neuronal birth-dating studies indicate that supercortex neurons were correctly layered, although adjacent mutant cortex neurons were in reversed order. Immunocytochemistry using Emx1, a marker for pyramidal neurons, indicates that the vast majority of Dab1(+/+) neurons in the supercortex were Emx1 immunoreactive. Confirmation of the pyramidal phenotype was demonstrated by the absence of GABA immunoreactivity among Dab1(+/+) cells in the supercortex. Myelin staining using 2'3'-cyclic nucleotide 3'-phosphodiesterase showed the supercortex was supported by a secondary white matter from which thick fiber tracts appear connected to the underlying mutant white matter. The presence of Dab1(+/+) cells failed to rescue inversion of cortical layers and the abnormal infiltration of the marginal zone by Dab1(+/+) cells. Conversely, mutant cells did not impose a mutant phenotype on adjacent wild-type neurons. These results suggest that Dab1 functions cell autonomously with respect to radial migration and cortical layering of pyramidal neurons.