APOLIPOPROTEIN ISOFORMS AND RETINAL DEGENERATION

描述（由申请人提供）：本研究的长期目标是了解视网膜中载脂蛋白的生物学，特别是特定载脂蛋白e亚型可能发挥（或缺乏）神经保护作用的机制。这个为期2年的探索性项目的直接目标是开发和表征必要的转基因小鼠品系，以实现长期目标。载脂蛋白e是一种参与胆固醇代谢和运输的蛋白质。在大脑中，载脂蛋白异构体被认为具有神经保护作用，并在中枢神经系统损伤后的恢复中发挥重要作用。相反，apoE4亚型是痴呆的危险因素，如阿尔茨海默病。矛盾的是，在年龄相关性黄斑变性（AMD）中，apoE4与发病率降低相关，这一趋势似乎正好相反。这种矛盾的原因仍然是一个谜，将需要适当的新模型系统来阐明所涉及的分子机制。作为实现这一目标的第一步，我们将开发新的小鼠品系，并评估apoE是否可以以同种异构体特异性的方式调节遗传性视网膜变性的严重程度和时间进程。携带rds（视网膜变性缓慢）突变和缺乏apoE基因的突变小鼠将与选择性表达人类apoES或apoE4亚型的小鼠杂交。基因型将通过PCR确认。与年龄匹配的rds和非转基因（野生型）对照小鼠进行比较，将使用Western blot分析和免疫细胞化学评估ApoE表达作为年龄的函数。视网膜变性将通过光镜和电镜进行评估；视网膜电图（ERG）评估视网膜功能。这项研究的临床意义在于，它有可能调节载脂蛋白e在视网膜中的神经保护同种异构体的表达，作为一种延缓或改善各种来源的人类视网膜变性的新疗法。因此，该项目有可能影响NEI使命的几个方面：帮助预防和治疗眼病和其他视力障碍；减少视力损害和失明；改善各年龄段人民的生活质量；并推进我们对视觉系统如何在健康和疾病中发挥作用的认识。

DESCRIPTION (provided by applicant): The long-range goal of this study is to understand the biology of apolipoproteins in the retina, particularly the mechanism by which specific apoE isoforms may exert (or lack) neuroprotective effects. The immediate goal of this 2-year exploratory project is to develop and characterize the requisite genetically altered mouse strains to pursue the long-range goal. ApoE is a protein involved in cholesterol metabolism and transport. In the brain, the apoES isoform is thought to be neuroprotective and to play an important role in recovery following CNS injury. In contrast, the apoE4 isoform is a risk factor for dementias, such as Alzheimer's disease. Paradoxically, the exact opposite trend seems to prevail in age-related macular degeneration (AMD), where apoE4 correlates with reduced incidence of disease. The reason for this paradox remains a mystery, and will require appropriate new model systems to elucidate the molecular mechanisms involved. As a first step toward that goal, we will develop novel mouse strains and assess whether apoE can modulate the severity and time course of hereditary retinal degeneration in an isoform-specific manner. Mutant mice harboring the rds (retinal degeneration slow) mutation and lacking the apoE gene will be cross-bred with mice that selectively express either the human apoES or apoE4 isoform. Genotype will be confirmed by PCR. ApoE expression will be assessed as a function of age using Western blot analysis and immunocytochemistry, in comparison with age-matched rds and non-transgenic (wild-type) control mice. Retinal degeneration will be assessed by light and electron microscopy; retinal function will be assessed by electroretinography (ERG). The clinical relevance of this study lies in the potential to modulate the expression of neuroprotective isoforms of apoE in the retina as a novel therapy to retard or ameliorate human retinal degenerations of various origins. As such, this project has the potential to impact several aspects of the NEI's mission: to help prevent and treat eye diseases and other disorders of vision; reduce visual impairment and blindness; improve the quality of life for people of all ages; and advance our knowledge of how the visual system functions in health and disease.