Identification of a Novel Lipofuscin Pigment (iisoA2E) in Retina and Its Effects in the Retinal Pigment Epithelial Cells*
Identification of a Novel Lipofuscin Pigment (iisoA2E) in Retina and Its Effects in the Retinal Pigment Epithelial Cells*
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DOI：
10.1074/jbc.m113.511386
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
Jie Li;Ke Yao;Xiaoning Yu;Xinran Dong;Lishe Gan;Chenqi Luo;Yalin Wu
中科院分区：
文献类型：
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作者：
Jie Li;Ke Yao;Xiaoning Yu;Xinran Dong;Lishe Gan;Chenqi Luo;Yalin Wu
背景：黄斑变性涉及视网膜中的脂褐质沉积。结果：对视网膜中的双维A酸 iisoA2E 进行了表征； iisoA2E 的过度积累对视网膜色素上皮细胞具有细胞毒性。结论：Pyridinium iisoA2E 是一种独特的直接视网膜加合物，可作为异常全反式视网膜代谢的荧光生物标志物。意义：iisoA2E 的表征可以让我们更全面地了解视网膜双视黄醇脂褐素的生物合成。眼睛视网膜色素上皮 (RPE) 细胞中脂褐质的积累与 Stargardt 病和年龄相关性黄斑变性（老年人失明的主要原因）的病因有关。在这里，我们鉴定出了一种以前未知的 RPE 脂褐质成分。通过一维和二维核磁共振技术和质谱分析，我们证实该化合物是一种新型的吡啶鎓双维甲酸，具有不寻常的结构，其中两个多烯侧链连接到吡啶鎓环的相邻碳上。这种色素是isoA2E的光致异构体，而不是A2E，简称iisoA2E。该色素是一种荧光脂褐素化合物，在人、猪、小鼠和牛眼中检测到最大吸光度为 430 和 352 nm。在全反式视黄醛和乙醇胺的反应混合物中发现了 iisoA2E 的形成。体外 RPE 细胞中该加合物在细胞内过量积累会导致细胞活力显着丧失并引起膜损伤。磷脂酶 D 介导的 A2PE 系列磷酸二酯裂解除了 A2E 之外还生成了 isoA2E 和 iisoA2E，从而证实了 isoA2PE 和 iisoA2PE 的存在，它们可以作为 isoA2E 和 iisoA2E 的生物合成前体。
Background: Macular degeneration implicates lipofuscin deposition in the retina. Results: Bisretinoid iisoA2E in the retina was characterized; excessive accumulation of iisoA2E was cytotoxic to retinal pigment epithelial cells. Conclusion: Pyridinium iisoA2E is a unique diretinal adduct and serves as a fluorescent biomarker of aberrant all-trans-retinal metabolism. Significance: Characterization of iisoA2E gives a more complete understanding of the biosynthesis of retinal bisretinoid lipofuscin. Lipofuscin accumulation in retinal pigment epithelial (RPE) cells of the eye implicates the etiologies of Stargardt disease and age-related macular degeneration, a leading cause of blindness in the elderly. Here, we have identified a previously unknown RPE lipofuscin component. By one- and two-dimensional NMR techniques and mass spectrometry, we confirmed that this compound is a new type of pyridinium bisretinoid presenting an unusual structure, in which two polyenic side chains are attached to adjacent carbons of a pyridinium ring. This pigment is a light-induced isomer of isoA2E, rather than A2E, referred to as iisoA2E. This pigment is a fluorescent lipofuscin compound with absorbance maxima at ∼430 and 352 nm detected in human, pig, mouse, and bovine eyes. Formation of iisoA2E was found in reaction mixtures of all-trans-retinal and ethanolamine. Excess intracellular accumulation of this adduct in RPE cells in vitro leads to a significant loss of cell viability and caused membrane damage. Phospholipase D-mediated phosphodiester cleavage of the A2PE series generated isoA2E and iisoA2E, in addition to A2E, thus corroborating the presence of isoA2PE and iisoA2PE that may serve as biosynthetic precursors of isoA2E and iisoA2E.