EARLY RESPONSE OF CORNEAL EPITHELIUM TO UV-INDUCED DEATH

描述（改编自申请人摘要）：暴露于紫外线是一种 严重的环境和职业危害，可能导致急性和 角膜的慢性炎症变化。我们在角膜领域的长期目标 上皮是表征细胞信号传导之间的相互作用， 途径，这是负责紫外线诱导的程序性细胞死亡 （凋亡）和致癌变化。我们发现，早期紫外线诱导的事件， 这些途径是刺激质膜K+通道活性， 通过激活应激诱导的SEK/JNK信号通路， 丝裂原活化蛋白激酶（MAPK）超家族成员。 有趣的是，抑制UV诱导的K+通道激活完全 通过抑制紫外线诱导的细胞凋亡， SEK和JNK激酶。验证K+通道活性的激活是一种 细胞凋亡诱导早期事件是抑制K+通道活性 与4-氨基吡啶不能保护角膜上皮细胞， 足叶乙甙诱导的细胞凋亡。因此，我们已经确定了一种新的机制， K+通道活性的改变可调节SEK/JNK活性， 兔角膜上皮细胞命运。然而，对其他人一无所知。 K+通道活性与其他信号通路的可能相互作用 在MAPK超家族以及其它上游受体（即EGFR、TNFR 1 和CD 95/FAS），它们都参与细胞凋亡的控制。我们 假设EGFR、TNFR 1和CD 95/Fas相关信号传导激活 紫外线诱导的K+通道介导了对紫外线辐射的响应 多动症。提出了三个具体目标，以确定：1）什么类型的 角膜上皮细胞中K+通道的活性及其与角膜上皮细胞的关系 2）改变K+通道活性对 EGFR、TNFR 1和CD 95/Fas信号通路的激活和UV应答 基因表达;以及3）在凋亡信号传导中是否发生串扰 与UV诱导的K+通道激活有关的途径。我们的研究结果将揭示新的 深入了解细胞信号相互作用，参与连接 细胞凋亡对紫外线照射的反应。此外，治疗措施可以是 确定了可以减少UV诱导的角膜凋亡的发生率 上皮损伤和角膜上皮对 感染和疾病。

DESCRIPTION (Adapted from applicant's abstract): Exposure to UV light is a significant environmental and occupational hazard capable of causing acute and chronic inflammatory changes in the cornea. Our long term goal in the corneal epithelium is to characterize the interactions among the cell signaling pathways, which are responsible for UV-induced programmed cell death (apoptosis) and oncogenic changes. We found that an early UV-induced event in these pathways is stimulation of plasma membrane K+ channel activity followed by activation of the stress-induced SEK/JNK signaling pathway, which is a member of the mitogen activated protein kinase (MAPK) superfamily. Interestingly, suppression of UV-induced K+ channel activation completely prevented UV-induced apoptosis through inhibition of UV-induced activation of SEK and JNK kinases. Validation that activation of K+ channel activity is an early event in apoptotic induction is that suppression of K+ channel activity with 4-aminopyridine could not protect corneal epithelial cells from etoposide-induced apoptosis. Thus, we have identified a novel mechanism in which changes in K+ channel activity can modulate SEK/JNK activity and primary rabbit corneal epithelial cell fate. However, nothing is known about other possible interactions linking K+ channel activity to other signaling pathways in the MAPK superfamily as well as other upstream receptors (i.e. EGFR, TNFR1 and CD95/FAS), which are all involved in the control of apoptosis. We hypothesize that activation of EGFR, TNFR1 and CD95/Fas linked signaling pathways in response to UV irradiation is mediated by UV-induced K+ channel hyperactivity. Three specific aims are proposed to determine: 1) what types of K+ channel are in corneal epithelial cells and how K+ channel activity is modulated by UV irradiation; 2) the effect of altered K+ channel activity on activation of EGFR, TNFR1 and CD95/Fas signaling pathways and UV-responding gene expressions; and 3)whether crosstalk occurs in the apoptotic signaling pathways linked to UV-induced K+ channel activation. Our results will shed new insight into the cell signaling interactions that are involved in linking the apoptotic response to UV irradiation. Furthermore therapeutic measures may be identified which could reduce the incidence of UV-induced apoptotic corneal epithelial damage and increases in corneal epithelial susceptibility to infection and diseases.