ABSTRACT

Deficit in locomotion (motor) ability and disturbance of the circadian behavior and sleep-wake pattern characterize Huntington’s disease (HD). Here, we examined the disturbance of circadian timing with the progression of HD pathogenesis, and tested the efficacy of melatonin and curcumin in preventing the motor deficit and disturbed eclosion behavior in the Drosophila model of HD. To examine circadian timing, we assayed mRNA expression of genes of the transcriptional feedback (TF) loop that generates the near 24-h rhythmicity. We performed qPCR of the Period, Timeless, Clock, Cycle, Clockwork, and Cryptochrome genes in transgenic fly heads from elav-Gal4 (pan neuronal) and PDF-Gal4 (PDF-specific neurons) driver lines through the progression of HD disease post-eclosion, from day 1 to its terminal stage on day 13. Cycle was arrhythmic from day 1, but Period and Timeless became arrhythmic on day 13 of the HD pathogenesis in elav, but not PDF, neurons. Twenty-four-hour mRNA rhythms showed alteration in the waveform properties (mesor and amplitude, not acrophase), but not in the persistence, in both elav-Gal4 and PDF-Gal4 HD flies; however, disturbance of the clock gene rhythm was delayed in PDF-Gal4 flies. To assess the preventive effects on HD pathogenesis, flies of both driver lines were provided with melatonin (50, 100, or 150 μg) or curcumin (10 μM) in the diet commencing from the larval stage. Both melatonin (100 μg) and curcumin reestablished the 24-h pattern in mRNA expression of Period and Timeless to normal (control) levels, and significantly improved both locomotion ability and eclosion behavior of HD flies. We suggest that the disturbance of circadian timekeeping progressively accelerated HD pathogenesis, possibly via modulation of the transcriptional state that resulted in the modification of the Huntington gene. These findings suggest melatonin and curcumin might be potential therapeutic agents for the treatment of HD in humans, although this needs specific investigation.

摘要

运动（运动）能力不足以及昼夜节律行为和睡眠-觉醒模式的障碍是亨廷顿病 (HD) 的特征。在这里，我们检查了随着 HD 发病机制进展的昼夜节律紊乱，并测试了褪黑激素和姜黄素在HD果蝇模型中预防运动缺陷和羽化行为紊乱的功效。为了检查昼夜节律时间，我们分析了产生近 24 小时节律性的转录反馈 (TF) 环基因的 mRNA 表达。我们对Period、Timeless、Clock、Cycle、Clockwork和Cryptochrome进行了 qPCR基因来自ELAV-GAL4（泛神经元）和PDF-GAL4（PDF特有的神经元）通过HD病后羽化的进展驾驶员线转基因苍蝇头，从1天到其终端上期13天周期是由心律失常第 1 天，但周期和永恒在 elav 而非 PDF 神经元 HD 发病机制的第 13 天变得心律失常。在 elav-Gal4 和 PDF-Gal4 HD 果蝇中，24 小时的 mRNA 节律显示波形特性（中频和振幅，而不是末期）发生变化，但在持续性方面没有变化；然而，时钟基因节律的干扰在 PDF-Gal4 果蝇中被延迟。为了评估对 HD 发病机制的预防作用，从幼虫阶段开始，在饮食中为两种驱动线的果蝇提供褪黑激素（50、100 或 150 μg）或姜黄素（10 μM）。褪黑激素（100 μg）和姜黄素均重建了Period和Timeless mRNA 表达的 24 小时模式到正常（对照）水平，并显着改善了 HD 果蝇的运动能力和羽化行为。我们认为昼夜节律计时的紊乱逐渐加速了 HD 的发病机制，可能是通过调节导致亨廷顿基因修饰的转录状态。这些发现表明褪黑激素和姜黄素可能是治疗人类 HD 的潜在治疗剂，尽管这需要具体研究。