EGFR-MEDIATED CORNEAL EPITHELIAL WOUND HEALING

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 角膜上皮损伤的愈合和动态平衡受表皮生长因子受体(EGFR)活性的调节。刺激角膜上皮细胞中的EGFR可诱导与角膜上皮损伤愈合相关的三种细胞变化：细胞迁移、增殖和层化。通过小分子抑制剂或封闭抗体抑制配体刺激的EGFR激活，会导致所有这三种细胞变化的减少，并损害伤口愈合。尽管有证据表明，表皮生长因子受体对角膜上皮细胞动态平衡和伤口愈合是必要的和充分的，但表皮生长因子的治疗作用有限。我们假设，EGFR的脱敏限制了EGF配体的治疗用途。脱敏是通过内化配体：受体复合体，通过笼蛋白包裹的小泡进入细胞内发生的。这种复合体通过内吞途径运输，通过早期和晚期的内小体，最终导致复合体的溶酶体降解。我们已经确定转化生长因子-α(转化生长因子-α)是一种配体，它改变了配体：受体复合体的内吞运输路线。用转化生长因子-α治疗促进了配体：受体复合体的内化，但不是针对溶酶体，而是促进受体循环到质膜。因此，EGFR可以发出更长时间的信号。信号增强的生理后果是增加角膜上皮细胞的迁移。由于目前尚不清楚细胞迁移的增加是由于EGFR信号的持续时间还是信号的空间位置，因此未来的研究将干扰离散内吞阶段的内吞运输，目的是做出这种区分。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Corneal epithelial wound healing and homeostasis is regulated by Epidermal Growth Factor Receptor (EGFR) activity. Stimulation of the EGFR in corneal epithelial cells induces the three cellular changes associated with corneal epithelial wound healing: cell migration, proliferation, and stratification. Inhibition of ligand-stimulated EGFR activation, either through small molecule inhibitors or blocking antibodies, results in a decrease in all three cellular changes as well as impaired wound healing. Despite evidence that the EGFR is necessary and sufficient for corneal epithelial homeostasis and wound healing, EGF has limited therapeutic utility. We hypothesize that desensitization of the EGFR limits the therapeutic use of EGF ligands. Desensitization occurs through internalization of the ligand:receptor complex via clathrin-coated vesicles into the cell. This complex traffics through the endocytic pathway through early and late endosomes and culminates with the lysosomal degradation of the complex. We have identified transforming growth factor-alpha (TGF-alpha) as a ligand that alters the itinerary of endocytic trafficking of the ligand:receptor complex. Treatment with TGF-alpha promotes internalization of the ligand:receptor complex, but rather than targeting it to the lysosome, promotes receptor recycling to the plasma membrane. As a result, the EGFR can signal for longer. The physiological consequence of enhanced signaling is an increase in corneal epithelial cell migration. Since it is not clear if the increase in cell migration is due to the duration of EGFR signaling or the spatial placement of signaling, future studies will disrupt endocytic trafficking at discrete endocytic stages with the goal of making this distinction.