Cohen Samia, Funkelstein Lydiane, Livet Jean, Rougon Geneviève, Henderson Christopher E, Castellani Valerie, Mann Fanny
INSERM UMR 623, Developmental Biology Institute of Marseille, CNRS-- INSERM--Univ--Mediterranee, Campus de Luminy, Case 907, 13288 Marseille cedex 09, France.
Eur J Neurosci. 2005 Apr;21(7):1767-76. doi: 10.1111/j.1460-9568.2005.04021.x.
Abstract In the spinal cord, motor neurons (MNs) with similar muscle targets and sensory inputs are grouped together into motor pools. To date, relatively little is known about the molecular mechanisms that control the establishment of pool-specific circuitry. Semaphorins, a large family of secreted and cell surface proteins, are important mediators of developmental processes such as axon guidance and cell migration. Here, we used mRNA in situ hybridization to study the expression patterns of semaphorins and their receptors, neuropilins and plexins, in the embryonic mouse spinal cord. Our data show that semaphorins and their receptors are differentially expressed in MNs that lie in distinct locations within the spinal cord. Furthermore, we report a combinatorial expression of class 3 (secreted) semaphorins and their receptors that characterizes distinct motor pools within the brachial and lumbar spinal cord. Finally, we found that a secreted semaphorin, Sema3A, elicits differential collapse responses in topologically distinct subpopulations of spinal MNs. These findings lead us to propose that semaphorins and their receptors might play important roles in the sorting of motor pools and the patterning of their afferent and efferent projections.
摘要 在脊髓中，具有相似肌肉靶点和感觉输入的运动神经元（MNs）被聚集在一起形成运动神经元池。迄今为止，对于控制池特异性神经回路建立的分子机制了解相对较少。信号素是一类分泌型和细胞表面蛋白的大家族，是轴突导向和细胞迁移等发育过程的重要介导因子。在这里，我们使用mRNA原位杂交技术研究信号素及其受体——神经纤毛蛋白和丛蛋白在胚胎小鼠脊髓中的表达模式。我们的数据表明，信号素及其受体在脊髓内不同位置的运动神经元中差异表达。此外，我们报告了3类（分泌型）信号素及其受体的组合表达，这是臂部和腰部脊髓内不同运动神经元池的特征。最后，我们发现一种分泌型信号素Sema3A在拓扑结构不同的脊髓运动神经元亚群中引发不同的塌陷反应。这些发现使我们提出，信号素及其受体可能在运动神经元池的分类以及其传入和传出投射的模式形成中发挥重要作用。
