Recently, circular RNAs (circRNAs) have been revealed to be an important non-coding element of the transcriptome. The brain contains the most abundant and widespread expression of circRNA. There are also indications that the circular transcriptome undergoes dynamic changes as a result of brain ageing. Diminished cognitive function with increased age reflects the dysregulation of synaptic function and ineffective neurotransmission through alterations of the synaptic proteome. Here, we present changes in the circular transcriptome in ageing synapses using a mouse model. Specifically, we observed an accumulation of uniquely expressed circular transcripts in the synaptosomes of aged mice compared to young mice. Individual circRNA expression patterns were characterized by an increased abundance in the synaptosomes of young or aged mice, whereas the opposite expression was observed for the parental gene linear transcripts. These changes in expression were validated by RT-qPCR. We provide the first comprehensive survey of the circular transcriptome in mammalian synapses, thereby paving the way for future studies. Additionally, we present 16 genes that express solely circRNAs, without linear RNAs co-expression, exclusively in young and aged synaptosomes, suggesting a synaptic gene network that functions along canonical splicing activity.

最近，环状RNA（circRNA）已被证明是转录组的重要非编码元件。大脑包含最丰富和广泛的circRNA表达。也有迹象表明，环状转录组由于脑衰老而发生动态变化。随着年龄的增长认知功能减弱反映出突触功能失调和通过突触蛋白质组的改变而导致的无效的神经传递。在这里，我们提出了使用小鼠模型的衰老突触中环状转录组的变化。具体来说，我们观察到与年轻小鼠相比，老年小鼠突触小体中独特表达的环状转录物的积累。个体circRNA表达模式的特征是幼鼠或老年小鼠突触小体中的丰度增加，而亲本基因线性转录本则观察到相反的表达。这些表达变化通过RT-qPCR验证。我们提供了哺乳动物突触中环状转录组的首次全面调查，从而为将来的研究铺平了道路。此外，我们提出了仅在年轻和老年的突触小体中仅表达circRNA而没有线性RNA共表达的16个基因，这表明突触基因网络沿规范的剪接活性起作用。