本试验旨在实现鸡血管生成素样蛋白4（ANGPTL4）重组蛋白的原核表达，并探讨其对肉鸡血清生化指标和激素水平的影响。将带有His-SUMO标签的鸡ANGPTL4基因亚克隆到大肠杆菌原核表达载体pET21a（+）的Nde Ⅰ和Xho Ⅰ双酶切位点上，构建重组原核表达质粒pET21a-His-SUMO-ANGPTL4，将重组质粒转化到大肠杆菌BL21（DE3）感受态细胞中，用异丙基-β-D-硫代半乳糖苷（IPTG）对其菌液进行诱导表达，经包涵体复性和复性蛋白的Ni柱纯化，得到预期大小的融合蛋白His-SUMO-ANGPTL4。将得到的鸡ANGPTL4重组蛋白按照0（对照）、20、100、500、2 500和12 500 ng/kg BW的剂量静脉注射给35日龄的健康爱拔益加肉公鸡，每个剂量注射6只，并于注射后30 min采集肉鸡的空腹血液。结果显示：1）与对照组相比，2 500和12 500 ng/kg BW鸡ANGPTL4重组蛋白组其血清葡萄糖（GLU）和极低密度脂蛋白（VLDL）含量均显著提高（P<0.05）；同时，随着鸡ANGPTL4重组蛋白注射剂量从0增加到12 500 ng/kg BW，血清GLU和VLDL含量均呈现一次线性和二次曲线增加的效应（P<0.05）。2）与对照组相比，20、2 500和12 500 ng/kg BW鸡ANGPTL4重组蛋白组血清生长激素水平显著降低（P<0.05）；同时，随着鸡ANGPTL4重组蛋白注射剂量从0增加到12 500 ng/kg BW，血清生长激素水平呈现一次线性和二次曲线降低的效应（P<0.05）。3）与对照组相比，20、100、500、2 500和12 500 ng/kg BW鸡ANGPTL4重组蛋白组血清瘦素水平显著降低（P<0.05）。由此可见，本试验实现了鸡ANGPTL4重组蛋白的原核表达，静脉注射2 500和12 500 ng/kg BW该重组蛋白均可显著提高肉鸡血清中GLU和VLDL含量，显著降低肉鸡血清中生长激素和瘦素水平。

The aim of this study was to accomplish the prokaryotic expression of chicken angiopoietin-like protein 4 (ANGPTL4) recombinant protein, and to investigate the effects of this recombinant protein on serum biochemical indices and hormone levels of broilers. The gene of chicken ANGPTL4 with a His-SUMO tag was cloned into Nde Ⅰ and Xho Ⅰsites of pET21a(+) vector to construct recombinant plasmid pET21a-His-SUMO-ANGPTL4. The recombinant plasmid was transformed into Escherichia coli BL21 (DE3) and the bacteria were induced with isopropy-β-D-thiogalactoside (IPTG). After inclusion body refolding, the refold protein was purified by Ni column and the expected size of fusion protein His-SUMO-ANGPTL4 was obtained. Thirty-six broilers at 35 days of age were subjected to one of the six following treatments:intravenous injection of chicken ANGPTL4 recombinant protein at the doses of 0 (control), 20, 100, 500, 2 500 and 12 500 ng/kg BW. Six broilers for each dose, and fasting blood samples of broilers were collected at 30 min after injection. The results showed as follows:1) compared with the control group, the contents of glucose (GLU) and very low-density lipoprotein (VLDL) in the serum of 2 500 and 12 500 ng/kg BW chicken ANGPTL4 recombinant protein groups were significantly increased (P<0.05). As the injected dose of chicken ANGPTL4 recombinant protein increased from 0 to 12 500 ng/kg BW, the contents of GLU and VLDL in the serum of broilers were linearly (P<0.05) and quadratically (P<0.05) increased. 2) Compared with the control group, the growth hormone (GH) level in the serum of 20, 2 500 and 12 500 ng/kg BW chicken ANGPTL4 recombinant protein groups were significantly decreased (P<0.05). As the injected dose of chicken ANGPTL4 recombinant protein increased from 0 to 12 500 ng/kg BW, the GH level in the serum of broilers were linearly (P<0.05) and quadratically (P<0.05) decreased. 3) Compared with the control group, the leptin level in the serum of 20, 100, 500, 2 500 and 12 500 ng/kg BW chicken ANGPTL4 recombinant protein groups were significantly decreased (P<0.05). It is concluded that the prokaryotic expression of chicken ANGPTL4 recombinant protein is successfully constructed in this study, and intravenous injection of this recombinant protein at the doses of 2 500 and 12 500 ng/kg BW can significantly increase the serum GLU and VLDL contents, and significantly decrease the serum GH and leptin levels of broilers.