DNA and RNA nanotechnology has been used for the development of dynamic molecular devices. In particular, programmable enzyme-free nucleic acid circuits, such as catalytic hairpin assembly, have been demonstrated as useful tools for bioanalysis and to scale up system complexity to an extent beyond current cellular genetic circuits. However, the intracellular functions of most synthetic nucleic acid circuits have been hindered by challenges in the biological delivery and degradation. On the other hand, genetically encoded and transcribed RNA circuits emerge as alternative powerful tools for long-term embedded cellular analysis and regulation. Herein, we reported a genetically encoded RNA-based catalytic hairpin assembly circuit for sensitive RNA imaging inside living cells. The split version of Broccoli, a fluorogenic RNA aptamer, was used as the reporter. One target RNA can catalytically trigger the fluorescence from tens-to-hundreds of Broccoli. As a result, target RNAs can be sensitively detected. We have further engineered our circuit to allow easy programming to image various target RNA sequences. This design principle opens the arena for developing a large variety of genetically encoded RNA circuits for cellular applications.

中文翻译：

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用于活细胞中灵敏 RNA 成像的基因编码催化发夹组装

DNA 和 RNA 纳米技术已用于动态分子装置的开发。特别是，可编程的无酶核酸电路，例如催化发夹组装，已被证明是生物分析的有用工具，并且可以将系统复杂性扩大到超出当前细胞遗传电路的程度。然而，大多数合成核酸回路的细胞内功能受到生物递送和降解挑战的阻碍。另一方面，基因编码和转录的 RNA 电路成为长期嵌入式细胞分析和调节的替代强大工具。在此，我们报道了一种基于基因编码的 RNA 催化发夹组装电路，用于活细胞内敏感的 RNA 成像。西兰花的分裂版本（一种荧光 RNA 适体）被用作报告基因。一种目标 RNA 可以催化触发数十到数百个西兰花的荧光。结果，可以灵敏地检测靶RNA。我们进一步设计了我们的电路，以便轻松编程以对各种目标 RNA 序列进行成像。这一设计原理为开发多种用于细胞应用的基因编码 RNA 电路开辟了舞台。