Sharma K, Sheng H Z, Lettieri K, Li H, Karavanov A, Potter S, Westphal H, Pfaff S L
Gene Expression Laboratory, The Salk Institute, La Jolla, California 92037, USA.
Cell. 1998 Dec 11;95(6):817-28. doi: 10.1016/s0092-8674(00)81704-3.
The circuits that control movement are comprised of discrete subtypes of motor neurons. How motor neuron subclasses develop and extend axons to their correct targets is still poorly understood. We show that LIM homeodomain factors Lhx3 and Lhx4 are expressed transiently in motor neurons whose axons emerge ventrally from the neural tube (v-MN). Motor neurons develop in embryos deficient in both Lhx3 and Lhx4, but v-MN cells switch their subclass identity to become motor neurons that extend axons dorsally from the neural tube (d-MN). Conversely, the misexpression of Lhx3 in dorsal-exiting motor neurons is sufficient to reorient their axonal projections ventrally. Thus, Lhx3 and Lhx4 act in a binary fashion during a brief period in development to specify the trajectory of motor axons from the neural tube.
控制运动的神经回路由不同类型的运动神经元组成。运动神经元亚类如何发育并将轴突延伸至其正确靶点，目前仍知之甚少。我们发现，LIM同源结构域因子Lhx3和Lhx4在轴突从神经管腹侧发出的运动神经元（v-MN）中短暂表达。在Lhx3和Lhx4均缺失的胚胎中运动神经元仍能发育，但v-MN细胞会改变其亚类身份，变成轴突从神经管背侧发出的运动神经元（d-MN）。相反，在背侧发出的运动神经元中过表达Lhx3足以使其轴突投射重新定向至腹侧。因此，Lhx3和Lhx4在发育过程中的一段短暂时期内以二元方式发挥作用，确定来自神经管的运动轴突的轨迹。
