UVR-INDUCED DNA DAMAGE AND ANGIOGENIC GROWTH FACTORS

皮肤和眼睛是身体唯一直接暴露于 太阳紫外线辐射（UVR）。 研究表明，干皮病 色素沉着个体缺乏DNA修复， 对UVR诱导的混浊和新生血管的敏感性 角膜和前眼癌。 平流层臭氧的前景 消耗和随之而来的人类暴露于紫外线的增加， 我们必须了解的急性和慢性反应的 哺乳动物眼睛暴露于UVR。 有袋动物Monodelphis arctica是一种 实验动物模型，特别适合于研究的作用， 特异性紫外线诱导的DNA损伤，嘧啶二聚体，在引起 暴露于UVR的眼睛的病理变化。 就像在表皮中， M.南极洲有一个高容量的 光复活（PR）修复紫外线诱导的嘧啶二聚体。 的 光依赖性PR修复途径具有仅修复 嘧啶二聚体;因此，如果PR降低UVR诱导 作为光生物学反应，一般认为嘧啶二聚体 在某种程度上参与了这种反应。 慢性紫外线照射对M.角膜炎诱发角膜肿瘤。 UVR 诱导角膜基质细胞和内皮细胞的增殖， 在肿瘤发展之前。 这似乎是合理的假设，紫外线在一些 诱导有丝分裂和血管生成生长的合成或分泌的方式 以自分泌或旁分泌方式起作用的因子， 角膜基质细胞和内皮细胞的增殖。 拟议 研究将证明DNA中未修复的嘧啶二聚体的假设 改变促有丝分裂和血管生成生长的合成和/或释放 紫外线暴露角膜中的因素。 这些早期的分子事件可能导致 增强了对紫外线辐射诱发癌症的易感性。 具体目标是： 1)RNA印迹和标准组织学技术将用于 确定血管生成生长因子表达的时间进程， 在长期照射的角膜中发生的病理变化。 PR 将用于定义DNA损伤在这些过程中的作用; 2）原位 杂交和免疫组织化学染色将用于鉴定 血管生成生长因子的合成和/或释放位点 长期照射角膜;和，3）作为DNA研究的延伸 角膜上皮修复，损伤特异性核酸酶与 碱性凝胶电泳将用于测量切除， 透镜中紫外线诱导的嘧啶二聚体的光复活修复 上皮DNA

Skin and eyes are the only organs of the body that are exposed directly to solar ultraviolet radiation (UVR). It has been shown that xeroderma pigmentosum individuals are deficient in DNA repair and have an increased susceptibility to UVR-induced opacification and neovascularization of the cornea and cancer of the anterior eye. The prospect of stratospheric ozone depletion and the accompanying increase in human exposure to UVR makes it imperative that we understand the acute and chronic responses of the mammalian eye to UVR exposure. The marsupial Monodelphis domestica is an experimental animal model uniquely suited for studies on the role of a specific UVR-induced DNA lesion, the pyrimidine dimer, in causing pathological changes in eyes exposed to UVR. As in the epidermis, cells in the corneal epithelium of M. domestica have a high capacity for the photoreactivation (PR) repair of UVR-induced pyrimidine dimers. The light-dependent PR repair pathway has the unique property of repairing only pyrimidine dimers; therefore, if PR decreases the ability of UVR to induce a photobiological response, it is generally accepted that pyrimidine dimers are in some way involved in initiating that response. Chronic UVR exposure of M. domestica induces tumors of the cornea. UVR induces proliferation of corneal stromocytes and endothelial cells which precedes tumor development. It seems reasonable to assume that UVR in some way induces the synthesis or secretion of mitogenic and angiogenic growth factors that act in an autocrine or paracrine manner to stimulate proliferation of corneal stromocytes and endothelial cells. The proposed research will lest the hypothesis that unrepaired pyrimidine dimers in DNA alters the synthesis and/or release of mitogenic and angiogenic growth factors in the UVR-exposed cornea. These early molecular events may result in enhanced susceptibility to UVR-induced cancer. The specific aims are: 1) RNA blotting and standard histological techniques will be used to determine the time course of angiogenic growth factor expression and pathological changes that occur in the chronically-irradiated cornea. PR will be used to define a role for DNA damage in these processes; 2) in situ hybridization and immunohistochemical staining will be used to identify the site of synthesis and/or release of angiogenic growth factors in the chronically irradiated cornea; and, 3) as an extension of studies on DNA repair in corneal epithelium, damage-specific nucleases in conjunction with alkaline gel electrophoresis will be used to measure the excision and photoreactivation repair of UVR-induced pyrimidine dimers in lens epithelial DNA.