Regulation of ephrin-A expression in compressed retinocollicular maps.
Regulation of ephrin-A expression in compressed retinocollicular maps.
复制标题
压缩视网膜小球图中肝配蛋白 A 表达的调节。
DOI：
10.1002/dneu.22059
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发表时间：
2013
影响因子：
3
通讯作者：
Pallas,SarahL
中科院分区：
文献类型：
--
作者：
Tadesse,Tizeta;Cheng,Qi;Xu,Mei;Baro,DeborahJ;Young,LarryJ;Pallas,SarahL
视网膜定位图可以随着靶点大小的变化而压缩和扩张，但这种补偿过程背后的机制仍然是一个谜。作为Sperry趋化亲和力过程的分子介体的ephins的发现，使我们能够以机械的方式来解决这一重要问题。在叙利亚仓鼠，新生，部分(PT)消融后上丘(SC)会导致视网膜定位图的压缩，这与神经活动无关。EphA受体与Ephin-A配基的渐进性排斥相互作用直接导致视网膜小球MAP的形成，但Ephin是否也参与MAP的压缩尚不清楚。为了验证MAP的压缩是否受ePhin表达模式的影响，我们采用原位杂交和实时定量聚合酶链式反应的方法，比较了正常SC和PTSC中eaffin-A2和eaffin-A5mRNA的表达。我们发现，与正常动物一样，在压缩的MAP中，ePhin-A配体的表达是前低后高。与我们的假设一致，在受损的丘脑中，肾上腺素梯度的陡度增加。有趣的是，在新生儿靶损伤后，ePhin-A2和-A5的总体表达水平立即下降，可能促进了轴突的生长。这些数据建立了ePhin-A梯度的变化与MAP压缩之间的相关性，并表明ePhin-A的表达梯度可能受靶点大小的调节。这反过来可能导致视网膜睫状体MAP压缩到减少的靶点上。这些发现对创伤性脑损伤的康复机制具有重要的意义。2012 Wiley期刊，Inc.开发神经生物学，2013年
Retinotopic maps can undergo compression and expansion in response to changes in target size, but the mechanism underlying this compensatory process has remained a mystery. The discovery of ephrins as molecular mediators of Sperry's chemoaffinity process allows a mechanistic approach to this important issue. In Syrian hamsters, neonatal, partial (PT) ablation of posterior superior colliculus (SC) leads to compression of the retinotopic map, independent of neural activity. Graded, repulsive EphA receptor/ephrin‐A ligand interactions direct the formation of the retinocollicular map, but whether ephrins might also be involved in map compression is unknown. To examine whether map compression might be directed by changes in the ephrin expression pattern, we compared ephrin‐A2 and ephrin‐A5 mRNA expression between normal SC and PT SC usingin situhybridization and quantitative real‐time PCR. We found that ephrin‐A ligand expression in the compressed maps was low anteriorly and high posteriorly, as in normal animals. Consistent with our hypothesis, the steepness of the ephrin gradient increased in the lesioned colliculi. Interestingly, overall levels of ephrin‐A2 and ‐A5 expression declined immediately after neonatal target damage, perhaps promoting axon outgrowth. These data establish a correlation between changes in ephrin‐A gradients and map compression, and suggest that ephrin‐A expression gradients may be regulated by target size. This in turn could lead to compression of the retinocollicular map onto the reduced target. These findings have important implications for mechanisms of recovery from traumatic brain injury. © 2012 Wiley Periodicals, Inc. Develop Neurobiol, 2013