Expansion of First-in-Class Drug Candidates That Sequester Toxic All-<i>Trans</i>-Retinal and Prevent Light-Induced Retinal Degeneration
作者:Jianye Zhang、Zhiqian Dong、Sreenivasa Reddy Mundla、X. Eric Hu、William Seibel、Ruben Papoian、Krzysztof Palczewski、Marcin Golczak
DOI:10.1124/mol.114.096560
日期:2015.3
All- trans -retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all- trans -retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11- cis -retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all- trans -retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all- trans -retinyl ester into 11- cis -retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation.
全反视黄醛是一种视黄酸代谢物,在光感受器光激活后自然产生,当其在视网膜中含量升高时具有细胞毒性。为了降低其毒性,人们已开发出两种实验验证的方法,包括抑制视黄酸循环和通过含有伯胺基团的药物捕获过量的全反视黄醛。我们鉴定了首批候选药物,这些药物通过暂时捕获该代谢物或通过抑制视觉色素11-顺式视黄醛的再生来减缓其产生。在眼睛中,有两种酶对视黄酸的循环至关重要。卵磷脂:视黄醇酰基转移酶(LRAT)是将从循环和光感受器细胞中捕获的维生素A(全反视黄醇)转化为酯化底物的酶,该底物供视黄酸异构酶(RPE65)使用,后者将全反视黄醇酯转化为11-顺式视黄醇。在此,我们研究了视黄胺及其衍生物,以评估它们对RPE65和LRAT的抑制剂/底物特异性、作用机制、效力、在眼睛中的保留能力以及对小鼠急性光诱导视网膜变性的保护作用。我们将视觉循环抑制水平与视网膜保护效应相关联,并概述了LRAT底物和RPE65抑制剂的化学边界,以获得对视网膜保持所需治疗特性的关键洞察。