新近研究发现环状RNA可通过吸附miRNAs参与基因表达调控。我们前期研究发现，一个由αs1-酪蛋白基因（CSN1S1）表达的环状RNA（cCSN1S1），是奶牛乳腺中表达量最高的环状RNA。它在泌乳动物乳腺中均高表达，且其表达量随泌乳期波动。生物信息学分析表明miR-204在CSN1S1 mRNA和cCSN1S1这两种RNA中均有多个高可信度的结合位点，这表明cCSN1S1可能通过吸附miR-204调控αs1-酪蛋白的合成。本项目拟通过RNA干扰和基因过表达技术相结合研究cCSN1S1和miR-204对αs1-酪蛋白合成的调控作用，并通过双荧光素酶报告基因法和RNA pull down技术深入探讨其作用机制。以期深入揭示乳蛋白合成调控机制，为奶牛分子育种和精准营养调控提供理论指导，并完善环状RNA调控理论。

Circular RNA acts as miRNA sponge to regulate gene expression. We found that a CSN1S1 derived circular RNA (cCSN1S1) was the highest expressed among cattle mammary gland circular RNAs. cCSN1S1 was conserved among mammal animals, varied depending on lactation stages. Both CSN1S1 mRNA and cCSN1S1 have putative miR-204 target sites, which indicated that cCSN1S1 can regulate the synthesis of αs1-casein through competitive binding to miR-204. We aim to investigate the function of cCSN1S1 and miR-204 on αs1-casein biosynthesis through gene knockdown and overexpression, and to discover the regulation mechanism through dual luciferase reporter gene assay and RNA pull down. The final objective is to discover the novel mechanism of αs1-casein biosynthesis regulation, and to provide the guide for improvement of milk protein production, and to improve the theory of regulatory circular RNA.