Lei Caixia, Tian Jingjing, Ji Hong
College of Animal Science and Technology, Northwest A&F University, 712100, Yangling, People's Republic of China.
Fish Physiol Biochem. 2017 Jun;43(3):813-822. doi: 10.1007/s10695-016-0336-x. Epub 2017 Jan 5.
This study was conducted to assess the effect of eicosapentaenoic acid (EPA) on grass carp preadipocyte glycerol kinase (GyK) expression, as well as to explore the mechanism. Here, we cloned partial sequence of grass carp GyK gene and analyzed its tissue distribution. The result showed that GyK gene expressed most in the liver, followed by adipose tissue and the kidney. Besides, 400 μM oleic acid (18:1n-9, OA) was used to establish a hypertrophic preadipocyte model. GyK gene expression and enzyme activity were significantly enhanced after model cells were treated with 100 μM eicosapentaenoic acid (20:5n-3, EPA) for 6, 12, and 24 h. Meanwhile, peroxisome proliferative-activated receptor (PPAR)γ, adipose triglyceride lipase (ATGL), and the two isoforms of grass carp HSL gene were first identified by Sun et al (2016), and they defined the two isoforms as HSLa and HSLb. Therefore, maybe HSLa and HSLb are appropriate.. The content of triglyceride was dramatically increased by EPA treatment for 24 h. Further, a competitive ATGL antagonist, HY-15859, attenuated the increase in GyK induced by EPA at 12 h. Surprisingly, the enhanced lipolysis and PPARγ gene expression induced by serum deprivation were paralleled by an increase in GyK gene expression, whereas a stabilization in GyK enzyme activity. Other fatty acids, including docosahexaenoic acid, alpha-linolenic acid, linoleic acid, and OA also promoted GyK gene expression. Moreover, an irreversible PPARγ antagonist, GW9662, was used to investigate the role of PPARγ in GyK induction. Data showed that GW9662 abolished the induction of GyK by EPA at 12 h. Together, these data suggested that EPA elevated grass carp preadipocytes GyK expression. ATGL and PPARγ contributed to the induction of GyK. PPARγ may be a key regulator in response to GyK expression induced by EPA.
本研究旨在评估二十碳五烯酸（EPA）对草鱼前脂肪细胞甘油激酶（GyK）表达的影响，并探讨其机制。在此，我们克隆了草鱼GyK基因的部分序列并分析了其组织分布。结果表明，GyK基因在肝脏中表达最多，其次是脂肪组织和肾脏。此外，使用400μM油酸（18:1n-9，OA）建立肥大前脂肪细胞模型。在用100μM二十碳五烯酸（20:5n-3，EPA）处理模型细胞6、12和24小时后，GyK基因表达和酶活性显著增强。同时，过氧化物酶体增殖物激活受体（PPAR）γ、脂肪甘油三酯脂肪酶（ATGL）以及草鱼HSL基因的两种同工型最初由Sun等人（2016年）鉴定，他们将这两种同工型定义为HSLa和HSLb。因此，也许HSLa和HSLb是合适的。EPA处理24小时后，甘油三酯含量显著增加。此外，一种竞争性ATGL拮抗剂HY-15859在12小时时减弱了EPA诱导的GyK增加。令人惊讶的是，血清剥夺诱导的脂解增强和PPARγ基因表达增加与GyK基因表达增加平行，而GyK酶活性稳定。其他脂肪酸，包括二十二碳六烯酸、α-亚麻酸、亚油酸和OA也促进了GyK基因表达。此外，使用一种不可逆的PPARγ拮抗剂GW9662来研究PPARγ在GyK诱导中的作用。数据表明，GW9662在12小时时消除了EPA对GyK的诱导。总之，这些数据表明EPA提高了草鱼前脂肪细胞GyK的表达。ATGL和PPARγ促成了GyK的诱导。PPARγ可能是响应EPA诱导的GyK表达的关键调节因子。
