猪脂肪酸去饱和酶编码基因FADS1/2相关cis-eQTL功能突变鉴定及其双向调控机制解析

FADS1和FADS2基因编码长链多不饱和脂肪酸合成的去饱和酶，被认为是猪2号染色体上肌肉多不饱和脂肪酸组成QTL的功能候选基因，但致因突变尚未鉴定。申请人前期在猪肌肉组织中鉴定到共同调控FADS1/2表达的cis-eQTL。这两个基因在染色体上共享启动子区域且向相反方向转录，我们认为存在功能性突变通过改变局部染色质状态而同时调控两个基因的表达，继而影响了脂肪酸的组成。本项目拟构建双向报告基因载体鉴定转录调控元件，利用启动子捕获Hi-C鉴定潜在增强子，据此注释鉴定出功能突变并进行验证。通过关联分析检验突变对猪肉多不饱和脂肪酸组成和肌内脂肪含量等性状的影响，构建小鼠模型检验其调控肌肉多不饱和脂肪酸组成的效应。本研究有望鉴定到调控FADS1/2双向表达的功能突变，深化人们对肌肉多不饱和脂肪酸组成性状形成基础的认识，并为猪肉质性状精准育种增添功能标记，所以本项目兼具重要理论价值和育种实践意义。

The FADS1 and FADS2 gene encode the desaturases of polyunsaturated fatty acid (PUFA) synthesis, which were proposed as the candidate genes of the QTL regulating muscle PUFA composition in pig chromosome 2, but the underlining causative mutation remains unknown. Previously, we identified the cis-eQTL regulating the expression level of FADS1 and FADS2 in skeletal muscle. These two genes shared promoter sequences and were transcripted divergently, from which we suppose that one functional mutation regulates the expression of both genes via modifying the local chromatin state, affecting the PUFA composition in muscle. Here, we are going to identify all potential transcriptional regulatory elements via bidirectional reporter assay, and characterize potential enhancers by the technology of promoter capture Hi-C. Then, all variants will be annotated based on the characterized regulatory elements, from which the potential functional variants will be figured out and validated. We will evaluate the mutant effect on meat quality and PUFA composition by association study, and evaluate the mutant effect on PUFA composition of skeletal muscle using the gene-editing mouse model targeting positive variant. The present study will identify the functional mutation regulating the bidirectional expression of FADS1 and FADS2, deepen our understanding to the genetics of pork PUFA composition and meat quality. And the characterized mutation will provide new functional marker for precision breeding of pig meat quality. Therefore, the present study has important theoretical value and practical significance in breeding.