β-胡萝卜素对肉牛皮下和肌内脂肪细胞脂质代谢差异性调控机制研究

Intramuscular fat (IMF) have a major influence on the beef quality. However, the fat deposition order determines it the hardest part to form. β-carotene (βC) has been proved to have relations to metabolism of fat, and the project team found in their previous that, βC supplementation in diet could repress the deposition of back fat and visceral fat but have no effect in intramuscular fat content . According to prior studies, βC paly function through its metabolites, Vitamin A (VA). However, recent researches from the project team indicated that βC may regulate back fat metabolism in its intact form, and showed different regulation models on fat deposition from different parts. The project will do future research on the different influences of βC on subcutaneous and intramuscular adipocytes and the underlying mechanisms in vitro on the levels of gene, protein and metabolism, with two key carotenoid-cleaving enzymes, β, β-carotene 15, 15'-monooxygenase 1 (BCMO1) and β-carotene-9', 10'-monooxygenase (BCO2), as pointcuts, hoping to provide theoretical support for marbling beef production through safe, efficient and low cost approaches.

肌内脂肪是决定牛肉品质的主要指标，但脂肪沉积次序决定了它最难合成。β-胡萝卜素（βC）已被证实与脂肪代谢有关，项目组前期研究发现，肉牛饲粮添加βC可在不影响肌内脂肪沉积的同时减少背部皮下脂肪和内脏脂肪的沉积。以往研究显示，βC对脂肪的影响是通过其代谢产物维生素A（VA）来实现的，但项目组近期研究发现，βC对肉牛皮下脂肪代谢的调控可能通过其本身结构发挥作用，且对不同部位脂肪沉积存在不同的调控机制。本课题拟从体外细胞水平出发，以βC分解关键基因β,β-胡萝卜素-15,15’-加氧酶（BCMO1）和β-胡萝卜素-9′,10′-双加氧脱氢酶（BCO2）为切入点，在基因、蛋白和代谢水平深入研究βC对肉牛皮下脂肪细胞和肌内脂肪细胞脂质代谢的不同影响及内在调控机制，以期为安全、高效、低成本生产大理石花纹牛肉提供理论支撑。

β-胡萝卜素（βC）已被证实与脂肪代谢调控有关，项目组前期研究发现，肉牛饲粮添加βC可在不影响肌内脂肪沉积的同时减少背部皮下脂肪和内脏脂肪的沉积。以往研究显示，βC对脂肪的影响是通过其代谢产物维生素A（VA）来实现的，但项目组早期研究发现，βC对肉牛皮下脂肪代谢的调控可能通过其本身结构发挥作用，且对不同部位脂肪沉积存在不同的调控机制。本项目以体外培养的肉牛皮下脂肪细胞和肌间脂肪细胞为研究对象，利用荧光灯定量PCR、免疫荧光染色、蛋白印迹等多种手段，系统研究了βC和不同形式VA对牛脂肪细胞增殖的影响，对不同分化阶段脂肪细胞内βC和VA代谢关键基因、脂肪分化关键转录因子以及脂肪酸水解关键基因表达的影响，并对BCMO1、BCO2基因RNA干扰进行了初步研究，以期为肉牛生产提供一定的理论支撑。