Mendelsohn Alana I, Dasen Jeremy S, Jessell Thomas M
Howard Hughes Medical Institute, Kavli Institute for Brain Science, Zuckerman Mind Brain Behavior Institute, Departments of Neuroscience and Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA.
Neuron. 2017 Feb 22;93(4):792-805.e4. doi: 10.1016/j.neuron.2017.01.017. Epub 2017 Feb 9.
The establishment of spinal motor neuron subclass diversity is achieved through developmental programs that are aligned with the organization of muscle targets in the limb. The evolutionary emergence of digits represents a specialized adaptation of limb morphology, yet it remains unclear how the specification of digit-innervating motor neuron subtypes parallels the elaboration of digits. We show that digit-innervating motor neurons can be defined by selective gene markers and distinguished from other LMC neurons by the expression of a variant Hox gene repertoire and by the failure to express a key enzyme involved in retinoic acid synthesis. This divergent developmental program is sufficient to induce the specification of digit-innervating motor neurons, emphasizing the specialized status of digit control in the evolution of skilled motor behaviors. Our findings suggest that the emergence of digits in the limb is matched by distinct mechanisms for specifying motor neurons that innervate digit muscles.
脊髓运动神经元亚类多样性的建立是通过与肢体中肌肉靶标的组织相一致的发育程序来实现的。手指的进化出现代表了肢体形态的一种特殊适应，但尚不清楚支配手指的运动神经元亚型的特化如何与手指的精细化过程并行。我们发现，支配手指的运动神经元可以通过选择性基因标记来定义，并通过一组变异的Hox基因表达以及不表达参与视黄酸合成的关键酶，与其他外侧脊髓运动神经元（LMC）区分开来。这种不同的发育程序足以诱导支配手指的运动神经元的特化，强调了手指控制在熟练运动行为进化中的特殊地位。我们的研究结果表明，肢体中手指的出现与支配手指肌肉的运动神经元特化的独特机制相匹配。
