血管生成素4(ANG4)是一种新型的抗菌肽，主要在哺乳动物的肠道组织表达，具有抗菌和促血管生成等功能，在机体对病原体的免疫过程和血管生成过程中发挥着重要的作用。鉴于该蛋白具有多种功能，ANG4在新生断奶仔猪肠道疾病防治方面具有非常广阔的前景。为了了解ANG4在仔猪肠道的表达特点，我们通过蛋白质免疫印迹、荧光定量PCR和免疫组化分析及其在肠道表达的细胞定位，分别确定了仔猪肠道内ANG4的mRNA、蛋白质表达水平以及在肠道表达的细胞定位。结果显示，ANG4的mRNA和蛋白质在仔猪肠道不同部位的变化趋势大致相同，除mRNA 水平在断奶后有一个明显下降外，mRNA和蛋白质表达水平呈现随着周龄的增加而升高的趋势。ANG4蛋白的表达基本都集中于小肠绒毛，腺窝处也有少量表达，主要的表达细胞为肠上皮细胞以及潘氏细胞。

ANG4 (angiogenin4), a novel antimicrobial peptide with antimicrobial activity and stimulating angiogenesis function mainly expressed in intestinal tissues of mammals, plays a key role in immune response of animal against pathogens and angiogenesis. Regarding to the multiple functions, ANG4 has a very broad prospect in the prevention and treatment of intestinal diseases of piglets. To determine the expression pattern of ANG4 in newborn piglet’s intestine, the mRNA and protein levels of ANG4 as well as the cellular localization were analyzed by real-time PCR, western blot, and immunohistochemistry respectively. The results showed that the change tendency of ANG4 in different parts of the piglet’s intestine was approximately the same. In the same tissue, the expression level of ANG4 gradually increased with the increase of the age of the week, and it increased significantly from the third week to the fifth week. In addition, during the same period, the expression of ANG4 in the ileum and colon was higher, followed by the jejunum, and the expression was lowest in the duodenum. The expression of ANG4 protein is mainly concentrated in the small intestine villi and crypt. The main expression cells are enterocytes and Paneth cells.