Einheber S, Schnapp L M, Salzer J L, Cappiello Z B, Milner T A
Department of Cell Biology, New York University Medical School, New York 10016, USA.
J Comp Neurol. 1996 Jun 17;370(1):105-34. doi: 10.1002/(SICI)1096-9861(19960617)370:1<105::AID-CNE10>3.0.CO;2-R.
Integrins are heterodimeric cell adhesion molecules comprised of alpha and beta subunits that have been implicated in the regulation of neuronal migration, differentiation, and process outgrowth. They mediate both cell-extracellular matrix and cell-cell interactions. The integrin alpha 8 beta 1 is a receptor for fibronectin, tenascin, and vitronectin that has been localized to axonal tracts and several types of non-neuronal cells in chick embryos and to smooth muscle cells in adult mammalian tissues. In this report, we describe the distribution of the alpha 8 subunit in the developing and adult mammalian brain. By light microscopy, alpha 8 labeling in the rat brain was found predominantly in neurons. It was primarily localized within perikarya and dendrites, but was also observed in certain fiber tracts. alpha 8 immunoreactivity was most concentrated in the olfactory bulb, hippocampal formation, substantia nigra, ventral tegmental area, and superior olivary complex, but was also found at moderate levels in several regions including layer 5 of the cerebral cortex. alpha 8 labeling was detected as early as E16, peaked in most areas during the first 3 postnatal weeks, and persisted in the adult. Electron microscopic analysis of the adult hippocampal formation revealed a striking concentration of alpha 8 immunoreactivity in the spines and postsynaptic densities of dendrites. These results suggest that alpha 8 is involved in the regulation of axonal and dendritic growth of some neurons in the developing central nervous system (CNS) and provide ultrastructural evidence that integrins may participate in the formation, maintenance, or plasticity of synapses.
整合素是由α和β亚基组成的异二聚体细胞黏附分子，与神经元迁移、分化及突起生长的调节有关。它们介导细胞与细胞外基质以及细胞与细胞之间的相互作用。整合素α8β1是纤连蛋白、腱生蛋白和玻连蛋白的受体，已定位到鸡胚的轴突束和几种非神经元细胞以及成年哺乳动物组织的平滑肌细胞中。在本报告中，我们描述了α8亚基在发育中和成年哺乳动物大脑中的分布。通过光学显微镜观察，发现大鼠脑中的α8标记主要存在于神经元中。它主要定位于胞体和树突内，但在某些纤维束中也有观察到。α8免疫反应性在嗅球、海马结构、黑质、腹侧被盖区和上橄榄复合体中最为集中，但在包括大脑皮层第5层在内的几个区域也有中等水平的表达。早在胚胎第16天就检测到α8标记，在出生后的前3周大多数区域达到峰值，并在成年期持续存在。对成年海马结构的电子显微镜分析显示，α8免疫反应性在树突棘和突触后致密物中显著集中。这些结果表明，α8参与发育中的中枢神经系统（CNS）中某些神经元轴突和树突生长的调节，并提供了超微结构证据，证明整合素可能参与突触的形成、维持或可塑性。
