Chen Li, Guo Qiuxia, Li James Y H
Department of Genetics and Developmental Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA.
Development. 2009 Apr;136(8):1317-26. doi: 10.1242/dev.030510. Epub 2009 Mar 11.
Relatively little is known about the development of the thalamus, especially its differentiation into distinct nuclei. We demonstrate here that Gbx2-expressing cells in mouse diencephalon contribute to the entire thalamic nuclear complex. However, the neuronal precursors for different thalamic nuclei display temporally distinct Gbx2 expression patterns. Gbx2-expressing cells and their descendents form sharp lineage-restriction boundaries delineating the thalamus from the pretectum, epithalamus and prethalamus, revealing multiple compartmental boundaries within the mouse diencephalon. Without Gbx2, cells originating from the thalamus abnormally contribute to the epithalamus and pretectum. This abnormality does not result from an overt defect in patterning or cell-fate specification in Gbx2 mutants. Chimeric and genetic mosaic analysis demonstrate that Gbx2 plays a cell-nonautonomous role in controlling segregation of postmitotic thalamic neurons from the neighboring brain structures that do not express Gbx2. We propose that, within the developing thalamus, the dynamic and differential expression of Gbx2 may be involved in the specific segregation of thalamic neurons, leading to partition of the thalamus into different nuclei.
关于丘脑的发育，尤其是其分化为不同核团的过程，我们所知相对较少。我们在此证明，小鼠间脑中表达Gbx2的细胞对整个丘脑核复合体有贡献。然而，不同丘脑核团的神经元前体表现出在时间上不同的Gbx2表达模式。表达Gbx2的细胞及其后代形成了清晰的谱系限制边界，将丘脑与顶盖前区、上丘脑和丘脑前区分开，揭示了小鼠间脑内的多个分区边界。没有Gbx2时，源自丘脑的细胞会异常地向上丘脑和顶盖前区贡献。这种异常并非由Gbx2突变体中明显的模式形成或细胞命运特化缺陷导致。嵌合体和遗传镶嵌分析表明，Gbx2在控制有丝分裂后丘脑神经元与不表达Gbx2的邻近脑结构的分离中发挥细胞非自主作用。我们提出，在发育中的丘脑中，Gbx2的动态和差异表达可能参与丘脑神经元的特异性分离，导致丘脑被分隔成不同的核团。
