Molecular mechanism for zone-to-zone projection of axons

我们发现了一种新的细胞粘附分子OCAM。OCAM在鼻上皮的2-4区的嗅觉感觉神经元中表达，而在1区的嗅觉感觉神经元中不表达。表达OCAM的嗅觉轴突选择性地投射到主嗅球的腹外侧区。这表明嗅觉轴突的“区域到区域投射”。对表达OCAM、neuropilin-1和BIG-2的嗅神经轴突的追踪表明，嗅球中的细胞粘附分子图和气味受体图之间存在着精确的对应关系。在副嗅系统中，OCAM在犁鼻感觉上皮的顶区感觉神经元中表达，而在基底区感觉神经元中不表达。表达OCAM的轴突选择性地投射到副嗅球（AOB）的吻侧区，表明犁鼻轴突的“区-区投射”。在胚胎和出生后早期的小鼠，OCAM选择性表达的二尖瓣/簇状细胞在尾区的AOB。细胞粘附分子分析表明，AOB中存在“信息素受体图”。在小脑皮层。在胚胎晚期和出生后早期，OCAM选择性表达。由浦肯野细胞的一个子集，这是分布在parasystrophy区。利用同源重组的方法，我们产生了缺乏OCAM I基因的小鼠。我们现在正在分析OCAM缺陷小鼠的形成和维持，以检查OCAM在脑中区域到区域投射的形成和维持中的作用。

We found a novel cell adhesion molecule OCAM. OCAM was expressed by olfactory sensory neurons in zones 2-4 but not by those in zone 1 of the nasal epithelium. OCAM-expressing olfactory axons projected selectively to ventrolateral zones of the main olfactory bulb. This indicates a "zone-to-zone projection" of olfactory axons. Tracing of olfactory axons expressing OCAM, neuropilin-1, or BIG-2 indicated that there exists a Precise correspondence between "cell adhesion molecule map" and "odorant receptor map" in the main olfactory bulb. In the accessory olfactory system, OCAM was expressed by apical zone sensory neurons but not by basal zone sensory neurons in the vomeronasal sensory epithelium. OCAM-expressing axons projected selectively to the rostral zone of the accessory olfactory bulb (AOB), indicating the "zone-to-zone projection" of vomeronasal axons. In the embryonic and early postnatal mice, OCAM was expressed selectively by mitral/tufted cells in the caudal zone of the AOB. Analyses with cell adhesion molecules suggested the existence of "pheromone receptor map" in the AOB. In cerebellar cortex. of late embryonic and early postnatal mice, OCAM was expressed selectively. by a subset of Purkinje cells, which were distributed within parasagittal zones. Using the homologous recombination method, we generated mice that lack OCAM I gene. We are now analyzing the and maintenance of the OCAM-deficient mice to examine the role of OCAM in the formation and maintenance of the zone-to-zone projection in the brain.