Kil S H, Bronner-Fraser M
Developmental Biology Center, University of California, Irvine 92717, USA.
Int J Dev Neurosci. 1996 Jun;14(3):181-90. doi: 10.1016/0736-5748(96)00006-8.
Integrins are cell surface receptors for a variety of extracellular matrix molecules including fibronectin, laminin and collagens. Although their role in development is not completely understood, they are likely to have important functions in cell migration and axon guidance. To characterize the types of integrins expressed in the developing nervous system, we have used monoclonal antibodies against alpha 7- and alpha v-integrin subunits to examine the distribution of these subunits in the early chick embryo. Low levels of alpha 7 immunoreactivity were first observed in the neural tube and developing myotome of stage 17 embryos (E2.5). Although low levels of alpha 7 expression were associated with most neuroepithelial cells, distinct alpha 7 immunoreactivity was first detected in the ventrolateral portions of the neural tube at a stage corresponding to the time when the first neurons differentiate. Its distribution pattern overlapped with that of commissural neurons in the developing spinal cord. alpha 7 was also prominently localized to the motor neurons and their axons emanating from the neural tube. In addition, alpha 7 immunoreactivity was observed on a subpopulation of trunk neural crest cells migrating through the somitic sclerotome. At later stages, alpha 7 expression was observed in other nervous system structures such as the pigmented retinal epithelial cells. In addition to its distribution in the developing nervous system, alpha 7 immunoreactivity was associated with early myotomal cells shortly after myotome formation and its expression persisted throughout myotome development. In contrast to alpha 7, alpha v-integrin had a limited distribution in the nervous system, being expressed only at low levels in the neural tube. However, alpha v displayed prominent immunoreactivity in the myotome and in endothelial cells of the dorsal aorta. The results suggest that alpha 7-integrin is one of the prevalent integrin subunits on neurons and axons in the developing spinal cord.
整合素是多种细胞外基质分子的细胞表面受体，这些分子包括纤连蛋白、层粘连蛋白和胶原蛋白。尽管它们在发育过程中的作用尚未完全明确，但它们可能在细胞迁移和轴突导向中发挥重要作用。为了表征发育中的神经系统中表达的整合素类型，我们使用了针对α7-和αv-整合素亚基的单克隆抗体，来检测这些亚基在早期鸡胚中的分布。在17期胚胎（E2.5）的神经管和发育中的肌节中首次观察到低水平的α7免疫反应性。虽然大多数神经上皮细胞都有低水平的α7表达，但在与第一批神经元分化时间相对应的阶段，首次在神经管的腹外侧部分检测到明显的α7免疫反应性。其分布模式与发育中的脊髓中连合神经元的分布模式重叠。α7也显著定位于运动神经元及其从神经管发出的轴突上。此外，在穿过体节生骨节迁移的躯干神经嵴细胞亚群上观察到α7免疫反应性。在后期阶段，在其他神经系统结构如色素性视网膜上皮细胞中观察到α7表达。除了在发育中的神经系统中的分布外，α7免疫反应性在肌节形成后不久就与早期肌节细胞相关，并且其表达在整个肌节发育过程中持续存在。与α7相反，αv-整合素在神经系统中的分布有限，仅在神经管中低水平表达。然而，αv在肌节和背主动脉的内皮细胞中显示出显著的免疫反应性。结果表明，α7-整合素是发育中的脊髓中神经元和轴突上普遍存在的整合素亚基之一。
