lpl-a序列特征及其过表达对脂肪变化的影响

THE SEQUENCE CHARACTERISTICS OF LPL-A IN COMMON CARP (CYPRINID CARPIO) AND THE EFFECTS OF ITS OVEREXPRESSION ON FAT DEPOSITION

  • 摘要: 为探究过表达鲤(Cyprinus carpio)脂蛋白脂肪酶a (lipoprotein lipase a, lpl-a)基因对脂肪沉积模式及脂代谢基因表达的影响, 本研究分析了鲤lpl-a基因序列及结构特征, 检测lpl-a在鲤5种体内组织(腹腔脂肪、肝、肾、肌肉、肠)的表达量, 基于同源重组技术构建鲤lpl-a过表达质粒载体, 导入斑马鱼活体和鲤肝细胞, 分析过表达lpl-a对总胆固醇(T-CHO)、甘油三酯(TG)含量及脂代谢标志基因(ppar γfabp 3pnpla 2等)表达的影响。结果, 预测鲤lpl-a有7个开放阅读框、编码507个氨基酸大小的蛋白质, 其在硬骨鱼的进化中有较高保守性; 体内组织表达显示lpl-a呈显著特异性表达, 腹腔脂肪、肝和肾表达量显著高于肌肉和肠(P<0.05)。构建鲤lpl-a过表达质粒载体, 个体层面, 斑马鱼(Danio rerio)显微注射过表达鲤lpl-a后, 肌肉T-CHO含量较野生型增加约7倍、肝脏T-CHO和TG含量均增加约1倍, 伴随肌肉和肝脏中lpl-appar γfabp 3等脂代谢相关基因表达上调; 细胞层面, 鲤肝细胞转染lpl-a过表达载体72h后, 该基因表达及脂解相关基因pnpla 2表达显著升高。分析表明, 过表达鲤lpl-a导致鲤科鱼类在个体和细胞层面呈现差异化的脂质代谢调控, 即个体中肌肉储脂增强与肝脏脂质积蓄, 细胞中脂解激活与合成抑制, 为靶向该基因调控经济动物脂肪沉积提供了理论依据。

     

    Abstract: To investigate the effects of overexpressing lipoprotein lipase a gene (lpl-a) in common carp (Cyprinid carpio) on fat deposition patterns and lipid metabolism-related genes expression, we analyzed the sequence and structural characteristics of the carp lpl-a gene and examined its tissue distribution using quantitative real-time (qPCR) in five internal tissues: abdominal fat, liver, kidney, muscle, and intestine. The lpl-a overexpression plasmid vector was constructed by homologous recombination and introduced into zebrafish (Danio rerio) and carp liver cells. The impacts of lpl-a overexpression on total cholesterol (T-CHO), triglyceride (TG) levels, and expressions of lipid metabolism marker genes (pparγ, fabp3, pnpla2, etc.) were assessed in zebrafish (individual level) and carp hepatocytes (cell level). Results showed that the carp lpl-a was predicted to encode a 507-amino acid protein with 7 open reading frames (ORFs), and it demonstrated high evolutionary conservation in osteichthyes. Tissue-specific expression analysis revealed significantly higher lpl-a transcript levels in abdominal fat, liver, and kidney compared to muscle and intestine (P<0.05). In zebrafish, microinjection of the lpl-a overexpression vector resulted in an approximately 7-fold increase in muscle T-CHO and a 1-fold increase in both T-CHO and TG in liver, accompanied by upregulation of lpl-a, ppar γ, and fabp 3 (P<0.05). In carp hepatocytes, transfection with the lpl-a construct for 72h significantly increased lpl-a and lipolytic gene pnpla 2 expressions (P<0.05). Altogether, these findings demonstrate that overexpression of lpl-a induced distinct lipid metabolism regulations at individual (enhanced muscle fat storage and hepatic lipid accumulation) and cellular (activated lipolysis and inhibited lipogenesis) levels, providing theoretical insights for targeting lpl-a to modulate lipid deposition in economically important aquatic animals.

     

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