Lewis Katharine E, Bates Jennifer, Eisen Judith S
Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA.
Dev Dyn. 2005 Jan;232(1):140-8. doi: 10.1002/dvdy.20215.
Specification of spinal cord neurons is regulated by several different transcription factors. In this study, we analyze expression and regulation of the transcription factor iro3 in zebrafish spinal cord. In addition to its broad expression in the progenitor domain of intermediate spinal cord, iro3 is also expressed in postmitotic ventral neurons, starting at early somitogenesis stages. Initially, this expression is only in two primary motoneurons, CaP and VaP, but by 24 hr postfertilization, iro3 is expressed by all classes of zebrafish spinal motoneurons as well as by a ventral interneuron called VeLD. iro3 expression in the progenitor domain of intermediate spinal cord is regulated independently from its expression in ventral neurons. Hedgehog (Hh) signaling is unnecessary for iro3 expression in intermediate spinal cord, but it is required to repress iro3 expression in the progenitor domain of ventral spinal cord. We also show that the basic helix-loop-helix transcription factor Olig2 is required for repression of iro3 expression in the progenitor domain of ventral spinal cord. We discuss our findings in the context of previous studies, suggesting that iro3 represses formation of motoneurons and promotes formation of interneurons.
脊髓神经元的特化受几种不同转录因子的调控。在本研究中，我们分析了斑马鱼脊髓中转录因子iro3的表达及调控。除了在脊髓中部祖细胞区域广泛表达外，iro3在有丝分裂后的腹侧神经元中也有表达，始于早期体节形成阶段。最初，这种表达仅存在于两个初级运动神经元CaP和VaP中，但在受精后24小时，iro3在所有类型的斑马鱼脊髓运动神经元以及一个名为VeLD的腹侧中间神经元中表达。脊髓中部祖细胞区域的iro3表达与其在腹侧神经元中的表达是独立调控的。刺猬信号通路（Hh）对于脊髓中部的iro3表达并非必需，但它对于抑制脊髓腹侧祖细胞区域的iro3表达是必需的。我们还表明，碱性螺旋-环-螺旋转录因子Olig2对于抑制脊髓腹侧祖细胞区域的iro3表达是必需的。我们结合之前的研究讨论了我们的发现，提示iro3抑制运动神经元的形成并促进中间神经元的形成。
