乳脂性状是奶牛育种中的重要目标性状，脂肪含量、脂肪酸含量及种类是决定乳品质的重要影响因素。深入研究与乳脂代谢相关的功能基因和作用机制是目前奶牛遗传育种领域的研究热点和亟待解决的关键科学问题之一。申请人前期在开展ACADSB和CD44基因功能研究时发现，PRSS2基因可能与ACADSB和CD44基因存在互作关系，并可能对乳脂代谢具有重要调控作用，但其调控机制尚不清楚。本研究拟以PRSS2为候选基因，通过过表达和RNA干扰初步分析其是否对乳脂代谢具有调控作用的基础上，采用CRISPR/Cas9技术，构建基因敲除细胞系及小鼠模型；诠释PRSS2基因对乳脂代谢的调控作用机制，解析PRSS2与参与乳脂代谢的功能基因ACADSB和CD44三者间的互作关系及调控网络。本项目研究将会为奶牛乳品质性状分子育种提供新的基因资源，并为进一步明确PRSS2基因的育种价值及相关性状的辅助选择提供理论依据。

Milk fat traits are important target traits in dairy cow breeding, fat content, the content and species of fatty acids are important factors influencing milk quality. In-depth study on the function and mechanism of genes related to milk fat metabolism is one of the current research hotspots in the field of cattle genetics and breeding. Our previous studies that verified the function of ACADSB and CD44 gene showed PRSS2 gene might have an interaction relationship with ACADSB and CD44 gene, and also may have an important regulatory effect on milk fat metabolism. However, its regulatory mechanism is still unclear. This study intends to select PRSS2 as a candidate gene. Based on preliminary analysis of whether PRSS2 has a regulatory effect on milk fat metabolism through over-expression and RNA interference to determine, and using CRISPR / Cas9 technology to construct knockout cell lines and mouse models, for further to interpret the regulation mechanism of PRSS2 gene on milk fat metabolism and analyze the interaction relationship between PRSS2 and the functional genes, ACADSB and CD44, involved in milk fat metabolism. Our study will provide a new genetic resource for molecular breeding of milk quality traits in cattle, and provide a theoretical basis for further clarifying the breeding value of the gene and the auxiliary selection of related traits.