Mechanisms of Chemically Induced Photosensitivity

这项研究的目的是阐明光(UVA和可见光辐射)单独或在内源或外源光敏剂存在下产生毒性或治疗作用的光化学和光生物学机制。UVA诱导的角质形成细胞凋亡与EGF受体内化和下调有关，而不是受体磷酸化和泛素化；UVA暴露还导致ERK MAP激酶的延迟和持续激活。我们已经确定皮肤脂质Cholesta-5，7，9(11)-Trien-3β-ol(9-DDHC)是导致Smith-Lemli-Opitz综合征患者UVA诱导皮肤光敏的推定因素。9-DDHC在UVA照射下产生单线态氧和超氧化物，对角质形成细胞具有光毒作用。A2E是一种脂类降解产物，存在于视网膜中的脂褐素颗粒中，对年轻眼睛具有光保护作用，但对老年眼睛可能具有光毒性。

The objective of this research project is to elucidate the photochemical and photobiological mechanisms whereby light (UVA and visible radiation) alone or in the presence of endogenous or exogenous photosensitizers exerts either toxic or therapeutic effects. UVA-induced apoptosis in keratinocytes is associated with EGF receptor internalization and down-regulation without receptor phosphorylation and ubiquitination; also UVA exposure causes delayed and sustained activation of ERK MAP kinase. We have identified the skin lipid cholesta-5,7,9(11)-trien-3 beta-ol (9-DDHC) as the putative agent responsible for UVA-induced skin photosensitivity in Smith-Lemli-Opitz syndrome patients. 9-DDHC generates singlet oxygen and superoxide upon UVA irradiation and is phototoxic to keratinocytes. A2E, a lipid degradation product found in lipofuscin granules deposited in the retina, is photoprotective in the young eye but may be phototoxic in older eyes.