Stettler O, Moya K L, Zahraoui A, Tavitian B
INSERM U 334, Service hospitalier Frédéric Joliot, Commissariat à l'Energie Atomique, Orsay, France.
Neuroscience. 1994 Sep;62(2):587-600. doi: 10.1016/0306-4522(94)90391-3.
Rab3A is a protein associated with the membrane of synaptic vesicles and is involved in the control of the targeting or docking of these vesicles at the presynaptic membrane for the release of neurotransmitters. Here, we have examined the expression and localization of this protein during the development of the rat brain. Relative to total protein, the concentration of rab3A greatly increased during brain development. Both the intracellular localization of the protein and its cerebral distribution showed an age-dependent shift. In contrast to other synaptic vesicle proteins, rab3A was heavily concentrated in cell bodies when immature neurons were migrating and during early differentiation. Later, the protein disappeared from perikarya and had a diffuse distribution in the neuropil, indicating a redistribution to nerve terminals, its exclusive localization in the adult. In the developing somatosensory cortex, rab3A delimited the modular organization of the barrels well after the afferents have arrived but just around the time that mature synaptic activity has been observed. In the hippocampus, rab3A defined a novel "blob-like" organization of the mossy fibre terminals and its appearance in terminal fields closely preceded the known onset of long-term potentiation. The appearance of rab3A in specific terminal fields during the period of increased physiological activity suggests that this small GTP-binding protein may be an important late element in the establishment of the mature characteristics of the presynaptic terminal.
Rab3A是一种与突触小泡膜相关的蛋白质，参与控制这些小泡在突触前膜的靶向或对接，以释放神经递质。在此，我们研究了该蛋白质在大鼠脑发育过程中的表达和定位。相对于总蛋白，rab3A的浓度在脑发育过程中大幅增加。该蛋白质的细胞内定位及其在大脑中的分布均呈现出年龄依赖性变化。与其他突触小泡蛋白不同，在未成熟神经元迁移和早期分化期间，rab3A大量集中在细胞体中。之后，该蛋白质从胞体消失，并在神经毡中呈弥散分布，这表明其重新分布到了神经末梢，而神经末梢是其在成体中的唯一定位。在发育中的体感皮层，在传入纤维到达后很久但就在观察到成熟突触活动的时候，rab3A很好地界定了桶状结构的模块化组织。在海马体中，rab3A定义了苔藓纤维末梢的一种新的“斑点状”组织，并且它在终末区域的出现紧接在已知的长时程增强开始之前。在生理活动增加期间，rab3A在特定终末区域的出现表明，这种小GTP结合蛋白可能是突触前终末成熟特征建立过程中的一个重要晚期因素。
