In mammals, a set of core clock genes form transcription–translation feedback loops to generate circadian oscillations. We and others recently identified a novel transcript at the Period2 (Per2) locus that is transcribed from the antisense strand of Per2. This transcript, Per2AS, is expressed rhythmically and antiphasic to Per2 mRNA, leading to our hypothesis that Per2AS and Per2 mutually inhibit each other's expression and form a double negative feedback loop. By perturbing the expression of Per2AS, we found that Per2AS transcription, but not transcript, represses Per2. However, Per2 does not repress Per2AS, as Per2 knockdown led to a decrease in the Per2AS level, indicating that Per2AS forms a single negative feedback loop with Per2 and maintains the level of Per2 within the oscillatory range. Per2AS also regulates the amplitude of the circadian clock, and this function cannot be solely explained through its interaction with Per2, as Per2 knockdown does not recapitulate the phenotypes of Per2AS perturbation. Overall, our data indicate that Per2AS is an important regulatory molecule in the mammalian circadian clock machinery. Our work also supports the idea that antisense transcripts of core clock genes constitute a common feature of circadian clocks, as they are found in other organisms.

中文翻译：

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Period2的天然反义转录本，Per2AS，调节小鼠生物钟的幅度

在哺乳动物中，一组核心时钟基因形成转录-翻译反馈回路以产生昼夜节律振荡。我们和其他人最近在Period2 ( Per2 ) 基因座上发现了一种新的转录本，它是从Per2的反义链转录而来的。这种转录本Per2AS与Per2 mRNA有节奏地和反相表达，导致我们假设Per2AS和Per2相互抑制彼此的表达并形成双负反馈回路。通过扰乱Per2AS的表达，我们发现Per2AS转录而非转录物抑制了Per2。然而，Per2基因不再加压Per2AS，如Per2基因敲低导致了降低Per2AS水平，表明Per2AS形式具有单个负反馈回路Per2基因和保持的电平Per2基因振荡范围内。Per2AS还调节生物钟的幅度，并且不能仅通过其与Per2 的相互作用来解释该功能，因为Per2敲低并不能概括Per2AS扰动的表型。总的来说，我们的数据表明Per2AS是哺乳动物生物钟机制中的重要调节分子。我们的工作还支持核心时钟基因的反义转录本构成生物钟的一个共同特征的观点，因为它们在其他生物中被发现。