Differential expression of Eph receptors and ephrins in the cochlear ganglion and eighth cranial nerve of the chick embryo.
Differential expression of Eph receptors and ephrins in the cochlear ganglion and eighth cranial nerve of the chick embryo.
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鸡胚耳蜗神经节和第八脑神经中 Eph 受体和 ephrins 的差异表达。
DOI：
10.1002/cne.20396
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Cramer,KarinaS
中科院分区：
文献类型：
--
作者：
Siddiqui,ShaziaA;Cramer,KarinaS
鸡的耳蜗前庭神经节在胚胎早期分化为第VIII神经轴突进入脑干。在轴突最初到达脑干目标时，可以辨别第VIII神经听觉部分的音调组织。这种早期组织的机制尚不清楚。Eph受体酪氨酸激酶和它们的配体肝配蛋白在引导轴突到神经系统的其它区域中的地形学上合适的位置中具有已证实的作用。为了开始测试Eph蛋白是否在听觉系统中具有类似的作用，我们研究了几种Eph受体和ephrins在胚胎年龄对应于听觉脑干的初始神经支配的第VIII神经中的tonotopic表达。在胚胎第4天至第10天，用免疫组织化学方法评价EphA 4、EphB 2、EphB 5、ephrin-A2和ephrin-B1的表达模式。在这些年龄段的耳蜗神经节和第VIII神经轴突中观察到蛋白质表达。EphB 5、ephrin-A2和ephrin-B1在整个神经中表达。EphA 4和EphB 2在神经内具有互补的表达模式，其中EphA 4在神经的背外侧部分中表达较高，EphB 2在神经的腹内侧部分中表达较高。这些区域可以分别对应于听觉和前庭分量。此外，EphA 4表达朝向耳蜗神经节细胞的中央和外周投射分支的低频区域更高。Eph蛋白表达的区域变化可能会影响第VIII神经投射的靶点选择和地形图。J. Comp.神经元482：309-319，2005.© 2005 Wiley利斯公司
The cochleovestibular ganglion of the chick differentiates at early embryonic stages as VIIIth nerve axons enter the brainstem. The tonotopic organization of the auditory portion of the VIIIth nerve can be discerned at the time axons initially reach their brainstem targets. The mechanisms underlying this early organization are not known. Eph receptor tyrosine kinases and their ligands, the ephrins, have a demonstrated role in guiding axons to topographically appropriate locations in other areas of the nervous system. In order to begin to test whether Eph proteins have a similar role in the auditory system, we investigated the tonotopic expression of several Eph receptors and ephrins in the VIIIth nerve during embryonic ages corresponding to the initial innervation of the auditory brainstem. Expression patterns of EphA4, EphB2, EphB5, ephrin‐A2, and ephrin‐B1 were evaluated immunohistochemically at embryonic days 4 through 10. Protein expression was observed in the cochlear ganglion and VIIIth nerve axons at these ages. EphB5, ephrin‐A2, and ephrin‐B1 were expressed throughout the nerve. EphA4 and EphB2 had complementary expression patterns within the nerve, with EphA4 expression higher in the dorsolateral part of the nerve and EphB2 expression higher in the ventromedial part of the nerve. These regions may correspond to auditory and vestibular components, respectively. Moreover, EphA4 expression was higher toward the low‐frequency region of both the centrally and peripherally projecting branches of cochlear ganglion cells. Regional variation of Eph protein expression may influence the target selection and topography of developing VIIIth nerve projections. J. Comp. Neurol. 482:309–319, 2005. © 2005 Wiley‐Liss, Inc.