REGENERATION OF CONE PIGMENTS & TREATMENT OF STARGARDT'S

描述(申请人提供)：文明人的视觉是中介的 很大程度上是通过视锥感光器。尽管圆锥体很重要，但更重要的是 知道棒子的生物学知识。视觉感知的第一步是 视觉色素分子对光子的吸收，导致11-顺式 视黄醛发色团的全反式异构化。在此之前 可以恢复光敏，必须全反式视黄醛 再异构化为11-顺式视黄醛。这涉及到一个多步骤的过程 被称为视觉循环，它主要是在杆状优势中计算出来的 物种。几行已发表的证据表明，视锥细胞感光器 通过另一种途径再生视觉色素。然而，什么都不知道， 关于这一替代途径的生物化学。我们最近确认了 三种新的催化活性在锥形优势的沙鼠和鸡中的应用 调节11-顺式视黄醛再生的视网膜 全反式视黄醇。这个应用程序的第一个目标将是净化和 克隆：(1)一种新的11-顺式视黄醇脱氢酶 视网膜色素上皮细胞中11-顺式视黄醇脱氢酶-5型； 全反式视黄醇异构酶，催化直接转化 全反式视黄醇转化为11-顺式视黄醇 来源；和(3)通过机制作用的11-顺式视黄酸酯合成酶 与卵磷脂-视黄醇酰基转移酶(LRAT)明显不同。我们计划 为了从功能上鉴定这些蛋白质，使用体外生化、细胞 培养表达和小鼠转基因/基因敲除系统。 隐性Stargardt病是一种遗传性黄斑变性 由ABCR基因突变引起。在上一个资助期内，我们 产生了abcr基因敲除突变的小鼠。这些动物的表型 与隐性遗传病患者的临床表型惊人地相似 Stargardt病，包括视网膜内脂褐素积聚 色素上皮。脂褐素蓄积似乎是一种关键事件 视网膜病理学的发展。此应用程序的第二个目标是 测试一种有前景的抑制脂褐素沉积的策略 Abcr-/-小鼠的光感受器退化。如果成功，这一战略应该会 导致启动对活动性Stargardt病患者的临床试验 疾病。

DESCRIPTION (provided by applicant): Vision in civilized man is mediated largely by cone photoreceptors. Despite the importance of cones, much more is known about the biology of rods. The first step in visual perception is absorption of a photon by a visual pigment molecule, which induces 11-cis to all-trans isomerization of the retinaldehyde chromophore. Before light-sensitivity can be restored, all-trans-retinaldehyde must be re-isomerized to 11-cis-retinaldehyde. This involves a multi-step process called the visual cycle, which has been worked out mainly in rod-dominant species. Several lines of published evidence suggest that cone photoreceptors regenerate visual pigment by an alternate pathway. Nothing is known, however, about the biochemistry of this alternate pathway. We have recently identified three new catalytic activities in cone-dominant ground squirrel and chicken retinas that mediate regeneration of 11-cis-retinaldehyde from all-trans-retinol. The first aim of this application will be to purify and clone the mRNA for: (1) a new 11-cis-retinol dehydrogenase distinct from the 11-cis-retinol dehydrogenase type-5 in retinal pigment epithelial cells; (2) an all-trans-retinol isomerase that catalyzes the direct conversion of all-trans-retinol to 11-cis-retinol utilizing fatty-acyl-CoAs as an energy source; and (3) an 11-cis-retinyl-ester synthase that acts by a mechanism clearly distinct from that of lecithin-retinol acyl transferase (LRAT). We plan to characterize these proteins functionally, using in vitro biochemical, cell culture expression, and mouse transgenic/knockout systems. Recessive Stargardt's disease is an inherited form of macular degeneration caused by mutations in the ABCR gene. During the previous funding period, we generated mice with a knockout mutation in abcr. The phenotype in these animals is strikingly similar to the clinical phenotype in patients with recessive Stargardt's disease, including accumulation of lipofuscin in the retinal pigment epithelium. Lipofuscin accumulation appears to be a critical event in the development of retinal pathology. The second aim of this application is to test a promising strategy for inhibiting lipofuscin deposition and photoreceptor degeneration in abcr-/- mice. If successful, this strategy should lead to the initiation of clinical trials on patients with active Stargardt's disease.