ABSTRACT

Extracellular vesicles (EVs) provide a novel intercellular communication mechanism to transfer biologically important molecules to target cells. Although several pieces of evidence have shown that EVs have potential to respond to bacterial infections, our knowledge about the role of circular RNA (circRNA), an important cargo of EV, behind this process remains poor. In particular, the mechanism by which circRNAs are packaged into EVs remains elusive during bacterial infection. In the present study, EVs from bovine milk samples with or without Staphylococcus aureus (S. aureus) infection were isolated. The presence of circRNAs in milk-derived EVs (MEVs) was validated for the first time by PCR amplification with convergent and divergent primers and the RNase R resistance test. Through high-throughput sequencing, the expression profile of circRNAs in EVs was found to be changed during S. aureus infection. Moreover, we demonstrated that circRNAs were selectively packaged into EVs. Finally, bioinformatic analyses predicted the involvement of differentially expressed circRNAs in immune functions. In summary, our findings offer an insight into the packaging mechanism of EV circRNAs and underscore the potential by which host used the EV circRNAs in response to pathogenic bacterial infections.

摘要

细胞外囊泡 (EV) 提供了一种新的细胞间通讯机制，可将重要的生物学分子转移到靶细胞。尽管有几项证据表明 EV 有可能对细菌感染做出反应，但我们对循环 RNA (circRNA)（EV 的重要货物）在该过程背后的作用的了解仍然很少。特别是，在细菌感染期间，circRNAs 被包装成 EVs 的机制仍然难以捉摸。在本研究中，来自含有或不含金黄色葡萄球菌（S. aureus) 感染被隔离。通过聚合引物和发散引物的 PCR 扩增以及 RNase R 抗性测试，首次验证了乳源性 EV（MEV）中 circRNA 的存在。通过高通量测序，发现 EV 中 circRNA 的表达谱在金黄色葡萄球菌感染期间发生了变化。此外，我们证明了 circRNA 被选择性地包装到 EV 中。最后，生物信息学分析预测了差异表达的 circRNA 参与免疫功能。总之，我们的研究结果提供了对 EV circRNA 包装机制的深入了解，并强调了宿主使用 EV circRNA 来应对病原性细菌感染的潜力。