The COP9 signalosome is required for light-dependent timeless degradation and Drosophila clock resetting.
The COP9 signalosome is required for light-dependent timeless degradation and Drosophila clock resetting.
复制标题
DOI：
10.1523/jneurosci.0429-08.2009
复制
发表时间：
2009-01-28
期刊：
影响因子：
--
通讯作者：
Blau J
中科院分区：
文献类型：
--
作者：
Knowles A;Koh K;Wu JT;Chien CT;Chamovitz DA;Blau J
泛素-蛋白酶体系统在分子钟成分的节律性积累和周转中起着重要作用。反过来，这些~24小时的分子节律驱动着行为和生理的昼夜节律。在果蝇中，泛素-蛋白酶体系统在时钟蛋白的光依赖性降解中也起着关键作用，这是分子时钟进入光-暗循环的关键步骤。在这里，我们研究了COP9信号体（CSN）在果蝇昼夜节律中的作用，这是一种蛋白质降解的一般调节剂。我们发现编码CSN4和CSN5亚基的基因的零突变阻止了起搏器侧神经元（LNs）中正常的TIM被光降解，正如显性阴性CSN5转基因的ln特异性表达一样。这些缺陷伴随着成年果蝇在LNs中缺乏正常CSN5活性的行为相移的强烈减少。TIM降解缺陷和行为阶段重置可通过过表达时差（JET）来修复，JET是光介导TIM降解所需的F-box蛋白。在所有时钟神经元中缺乏正常CSN活性的果蝇在恒定光下有节律性，这种表型先前与喷射突变有关。总之，这些数据表明JET和CSN在一个共同的途径上导致依赖光的TIM降解。令人惊讶的是，我们发现在持续黑暗条件下，强烈抑制CSN活性的操作对昼夜节律的影响最小，这表明CSN在光介导的TIM降解中具有特定作用。
The ubiquitin–proteasome system plays a major role in the rhythmic accumulation and turnover of molecular clock components. In turn, these ~24 h molecular rhythms drive circadian rhythms of behavior and physiology. In Drosophila, the ubiquitin–proteasome system also plays a critical role in light-dependent degradation of the clock protein Timeless (TIM), a key step in the entrainment of the molecular clocks to light– dark cycles. Here, we investigated the role of the COP9 signalosome (CSN), a general regulator of protein degradation, in fly circadian rhythms. We found that null mutations in the genes encoding the CSN4 and CSN5 subunits prevent normal TIM degradation by light in the pacemaker lateral neurons (LNs) as does LN-specific expression of a dominant-negative CSN5 transgene. These defects are accompanied by strong reductions in behavioral phase shifts of adult flies lacking normal CSN5 activity in LNs. Defects in TIM degradation and resetting of behavioral phases were rescued by overexpression of Jetlag (JET), the F-box protein required for light-mediated TIM degradation. Flies lacking normal CSN activity in all clock neurons are rhythmic in constant light, a phenotype previously associated with jet mutants. Together, these data indicate that JET and the CSN lie in a common pathway leading to light-dependent TIM degradation. Surprisingly, we found that manipulations that strongly inhibit CSN activity had minimal effects on circadian rhythms in constant darkness, indicating a specific role for the CSN in light-mediated TIM degradation.