REGULATION OF AXON GUIDANCE MOLECULE GENES: RELEVANCE TO BRAIN ADAPTATION

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。越来越多的证据表明，成年啮齿类动物大脑中Eph/ephrin蛋白可能调节突触功能、学习、记忆和对药物的适应，这重新确立了这些蛋白主要在神经发育中起作用的传统观点。Eph/ephrin在成年灵长类动物脑中的区域表达尚不清楚，我们试图绘制Eph/ephrin家族成员在成年非人灵长类动物脑中的mRNA和蛋白表达图谱。我们重点研究了EphA4、EphB1受体和ephrin B2配体，因为它们的转录物与神经适应有关。我们现在证明了成年旧世界猴和新世界猴的大脑表达Eph/ephrin mRNA和编码蛋白。EphA4蛋白的免疫细胞化学定位显示，在尾状核/壳核、白球、黑质、小脑浦肯野细胞、额叶皮层锥体细胞和海马亚颗粒区离散表达。EphA4在多巴胺神经元中表达的证据来自于纹状体、黑质和腹侧被盖区酪氨酸羟酶阳性终末的共定位。Ephrin-B2在脑各区域均有表达，但染色弱于EphA4。一些表达EphA4的区域（如黑质、腹侧被盖区）也表达ephrinB2。在成年灵长类动物大脑中，ephrinB2与EphA4接近，这与ephrinB2与Eph受体可能相互作用，调节NMDA受体、记忆形成等脑功能是一致的。这一信息将有助于阐明Ephs/ephrins在成瘾药物和治疗药物介导的神经适应过程中的作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Mounting evidence that Eph/ephrin proteins in adult brain of rodents may regulate synaptic function, learning, memory and adaptation to drugs, is reformulating the conventional view that these proteins function primarily in neurodevelopment. Regional expression of Eph/ephrin in adult primate brain is uncharted and we sought to map mRNA and protein expression of Ephs/ephrin family members in adult nonhuman primate brain. We focused on EphA4, EphB1 receptors and ephrin B2 ligand, as their transcripts are implicated in neuroadaptation. We now demonstrate that brains of adult old and new world monkeys express Eph/ephrin mRNA and encoded proteins. Immunocytochemical localization of EphA4 protein revealed discrete expression in caudate/putamen, globus pallidus, substantia nigra, cerebellar Purkinje cells, pyramidal cells of frontal cortices and the subgranular zone of the hippocampus. Evidence for EphA4 expression in dopamine neurons emerged from colocalization with tyrosine hydroxylase-positive terminals in striatum, substantia nigra and ventral tegmental area. Ephrin-B2 expression was found in all brain regions, but staining was weaker than EphA4. Several regions that expressed EphA4 (e.g. substantia nigra, ventral tegmental area) also expressed ephrinB2. The close proximity of ephrinB2 with EphA4 in the adult primate brain is consistent with a potential interaction of ephrinB2 and Eph receptors to modulate NMDA receptors, memory formation and other functions of brain. This information will be instrumental in clarifying the contributions of Ephs/ephrins to neuroadaptative processes mediated by addictive and therapeutic drugs.