嗅觉神经中的轴突行为反映了连环蛋白-钙黏蛋白介导的黏附作用。
Axon behavior in the olfactory nerve reflects the involvement of catenin-cadherin mediated adhesion.
作者信息
Akins Michael R, Greer Charles A
机构信息
Interdepartmental Neuroscience Graduate Program, Yale University School of Medicine, New Haven, Connecticut 06520-8082, USA.
出版信息
J Comp Neurol. 2006 Dec 20;499(6):979-89. doi: 10.1002/cne.21147.
The projection of olfactory sensory neuron (OSN) axons to the olfactory bulb (OB) is a complex but well-regulated process. Although odorant receptor proteins, and other molecules, are implicated in this process, our understanding remains incomplete. We demonstrate that axons remain restricted to the outer olfactory nerve layer (ONLo) until they are proximal to their target glomeruli, where they enter the inner ONL (ONLi), dividing the ONL into extension and sorting zones. Sorting is likely contingent on cell:cell interactions mediated in part by cell adhesion molecules. The cadherins are a large family of adhesion molecules whose function is contingent on their intracellular binding partners, the catenins, which in turn link to the cytoskeleton. We previously demonstrated that the organization of the cytoskeleton changed as olfactory sensory neuron axons moved from the ONLo to the ONLi. To further assess the role of cadherin mediated adhesion in the developing mouse ONL, we localized alpha-, beta-, gamma-, delta-, and p120-catenins as well as neural cadherin (N-cadherin; CDH2) in the OB. alpha- and beta-catenins are found throughout the OB and are uniform throughout the ONL. In contrast, gamma-catenin and CDH2 are expressed predominantly in the ONLo during perinatal development, but are uniform across the ONL beginning at P7 and into adulthood. Finally, p120- and delta-catenins are expressed in nonoverlapping patterns by olfactory axons and OB neuronal dendrites, respectively. We conclude that gamma-catenin-mediated CDH2 adhesion may influence OSN targeting by restricting axons to the ONLo until they reach the appropriate domain of the OB.
嗅觉感觉神经元(OSN)轴突向嗅球(OB)的投射是一个复杂但调控良好的过程。尽管气味受体蛋白和其他分子参与了这一过程,但我们的理解仍不完整。我们证明,轴突在靠近其目标肾小球之前一直局限于外嗅神经层(ONLo),在那里它们进入内嗅神经层(ONLi),将嗅神经层分为延伸区和分选区。分选可能取决于部分由细胞粘附分子介导的细胞间相互作用。钙粘蛋白是一大类粘附分子,其功能取决于它们的细胞内结合伙伴连环蛋白,而连环蛋白又与细胞骨架相连。我们之前证明,随着嗅觉感觉神经元轴突从ONLo移动到ONLi,细胞骨架的组织发生了变化。为了进一步评估钙粘蛋白介导的粘附在发育中的小鼠嗅神经层中的作用,我们在内嗅球中定位了α -、β -、γ -、δ -和p120 -连环蛋白以及神经钙粘蛋白(N -钙粘蛋白;CDH2)。α -和β -连环蛋白在内嗅球各处均有发现,且在嗅神经层中分布均匀。相比之下,γ -连环蛋白和CDH2在围产期发育期间主要在内嗅神经层外区(ONLo)表达,但从出生后第7天开始直至成年,它们在整个嗅神经层中分布均匀。最后,p120 -和δ -连环蛋白分别由嗅觉轴突和嗅球神经元树突以不重叠的模式表达。我们得出结论,γ -连环蛋白介导的CDH2粘附可能通过将轴突限制在内嗅神经层外区直到它们到达嗅球的适当区域来影响嗅觉感觉神经元的靶向。