Ko Ji-Ae, Morishige Naoyuki, Yanai Ryoji, Nishida Teruo
Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.
Biochem Biophys Res Commun. 2008 Dec 5;377(1):104-8. doi: 10.1016/j.bbrc.2008.09.085. Epub 2008 Oct 1.
Semaphorins are a family of glycoproteins that play an important role in repulsive axon guidance during embryogenesis. We have now investigated the effect of corneal epithelial cells on the expression of Sema3A in corneal fibroblasts with the use of a coculture system in which the two cell types are separated by a collagen vitrigel membrane. Reverse transcription-polymerase chain reaction and immunoblot analyses revealed that the presence of immortalized human corneal epithelial (HCE) cells increased the expression of Sema3A in human corneal fibroblasts at both the mRNA and protein levels. This effect of HCE cells was mimicked by recombinant human epidermal growth factor (EGF) in a concentration- and time-dependent manner. An inhibitor of the tyrosine kinase activity of the EGF receptor, PD153035, blocked the EGF-induced up-regulation of both Sema3A mRNA and protein in corneal fibroblasts. Depletion of EGF in HCE cells by RNA interference largely abolished the effect of these cells on Sema3A expression in corneal fibroblasts. These findings indicate that EGF released from corneal epithelial cells up-regulates the expression of Sema3A in corneal fibroblasts. This effect of EGF may play an important role in maintenance of corneal structure and repair of corneal damage.
信号素是一类糖蛋白家族，在胚胎发育过程中的轴突排斥导向中发挥重要作用。我们现在利用一种共培养系统研究了角膜上皮细胞对角膜成纤维细胞中Sema3A表达的影响，在该系统中两种细胞类型被胶原玻璃体膜分隔开。逆转录-聚合酶链反应和免疫印迹分析显示，永生化人角膜上皮（HCE）细胞的存在在mRNA和蛋白质水平上均增加了人角膜成纤维细胞中Sema3A的表达。重组人表皮生长因子（EGF）以浓度和时间依赖性方式模拟了HCE细胞的这种作用。EGF受体酪氨酸激酶活性抑制剂PD153035阻断了EGF诱导的角膜成纤维细胞中Sema3A mRNA和蛋白质的上调。通过RNA干扰耗尽HCE细胞中的EGF在很大程度上消除了这些细胞对角膜成纤维细胞中Sema3A表达的影响。这些发现表明，角膜上皮细胞释放的EGF上调了角膜成纤维细胞中Sema3A的表达。EGF的这种作用可能在维持角膜结构和角膜损伤修复中发挥重要作用。
