ABC转运蛋白在大鼠肝脏卵圆细胞中的表达

Expressions of ATP binding cassette transporter genes in rat hepatic oval cells

目的研究ABC转运蛋白基因家族的三个主要成员MDR1、MRP1和Bcrp1基因在大鼠肝脏卵圆细胞中的表达及意义。方法建立大鼠2-乙酰氨基芴／三分之二肝切除模型，两步胶原酶灌注结合Percoll密度梯度离心分离大鼠肝脏卯圆细胞和肝细胞，采用免疫组织化学染色检测大鼠肝脏组织中MDR1、MRP1、Bcrp1转运蛋白的表达；采用荧光定量PCR方法检测MDR1、MRP1和Bcrp1基因mRNA在卵圆细胞和肝细胞中的表达水平。结果免疫组织化学染色显示大鼠肝脏组织中MDR1表达位于门静脉区附近，呈放射状分布，Bcrp1表达定位在细胞膜上。大鼠肝脏卵圆细胞MDR1、MRP1和Bcrp1基因mRNA的表达水平分别是肝细胞的9倍、1．5倍和13．8倍。结论卵圆细胞表达高水平的ABC转运蛋白，后者参与卵圆细胞免受外源性化学物质损伤的自我保护机制。

Objective Liver regeneration occurs through hepatocytes after acute liver injury. However, severe liver injury activates bipotential oval cells from canals of Hering which can differentiate into hepatocytes and biliary epithelial cells. Most models of oval cell activation have employed potential carcinogens to inhibit hepatocyte replication in the face of a regenerative stimulus. Oval cells must be able to withstand the toxic milieu of the damaged liver. ATP binding cassette transporters are cytoprotective efflux pumps that may contribute to the protection of these cells. The aim of this study was to determine the ABC transporter expressions in hepatic oval cells. Methods A rat model was established by feeding 2-acetylaminofluorene combined with partial hepatectomy to activate hepatic oval cells. Oval cells were isolated and purified using selective enzymatic digestion and density gradient centrifugation from the heterogeneous hepatic cell population. The expressions of ABC transporter gene, including MDR1, MRP1 and Bcrp 1, in isolated hepatic oval cells and hepatocytes were measured by quantitative real-time reverse transcription-polymerase chain reaction and those in rat liver tissues were measured by immunohistochemistry. Results Compared to those in the rat hepatocytes, mRNA expressions of the genes encoding MDR1, MRP1 and Bcrpl were increased up to 9-, 1.5- and 13.8-folds in hepatic oval cells. Immunohistochemical staining of rat liver slides demonstrated that the expression of MDR1 proteins was found around periportal areas, and Bcrpl protein was found located on cell membranes. Conclusion Hepatic oval cells express high levels of the ABC transporter gene that may have cytoprotective functions during severe hepatotoxicity.