HNF4α和HNF6 mRNA在小鼠肝发育过程中的表达

目的 探讨HNF4α和HNF6在肝发育过程中的作用。方法 用RT-PCR和原位杂交检测HNF4α mRNA和HNF6 mRNA在胚胎第8、9、13、15、17d(E8、E9、E13、E15、E17)、出生后第1d(P1)以及成年小鼠肝中的表达。结果 RT-PCR结果显示，HNF4α在肝中的表达始于E9，并持续到新生，至成年时表达减弱。原位杂交结果显示．在胚胎发育的各个阶段多数肝索细胞呈HNF4α阳性反应，成年时仍有少数HNF4α阳性的肝索细胞，而胆管板及胆管上皮细胞、血管内皮细胞、造血细胞等均为阴性。HNF6 mRNA的表达在E9开始出现，E13消失，E15又重新出现，并一直维持到出生。E9、E15多数肝索细胞呈HNF6 mRNA阳性反应，E17及P1 HNF6 mRNA在肝索细胞中的反应减弱，胆管板细胞出现强阳性反应。结论 HNF4α mRNA表达与肝芽的形成有关，并参与肝干细胞向肝细胞的增殖、分化的过程，其在正常成年肝中的表达可能与肝细胞正常形态的维持有关。HNF6可能在肝干细胞的形成和肝干细胞向胆管细胞的分化，以及胆管细胞的增殖、分化过程中发挥作用，其在正常成年肝中可能介导维持胆管上皮细胞的正常形态。

Expression of HNF4α and HNF6 mRNA during the Process of Mouse Liver Development

OBJECTIVE: To investigate the function of HNF4a and HNF6 during liver development. METHODS: The expression levels of HNF4alpha and HNF6 at E8, 9, 13, 15, 17, P1 and in adult mouse liver were detected by RT-PCR and in situ hybridization. RESULTS: RT-PCR results showed that HNF4alpha first expressed at E9, the time of liver bud formation, and lasted through all gestation and existed in adult liver. In situ hybridization showed that the expression of HNF4alpha was detected at the cells of liver cords during various stages of mouse liver development, and there were still a few HNF4alpha positive hepatocytes in adult liver. The cells of bile duct plate and biliary epithelial cells, endothelial cells, hematopoietic cells of liver were negative for HNF4alpha. The expression of HNF6 mRNA was detected in the liver at E9, the time of liver formation onset. Then, HNF6 mRNA disappeared transiently at E13, but it appeared again at E15. Its expression lasted until adult. In situ hybridization studies showed that most liver cord cells were positive for HNF6 at E9 and E15. At E17 and P1, the expression levels of liver cord cells declined, and HNF6 strongly expressed in the cells of bile duct plate and biliary epithelial cells. CONCLUSION: HNF4alpha could modulate the formation of liver bud, trigger the differentiation of hepatic stem cell towards hepatocytes, and keep the shape of hepatocytes. HNF6 might play a role at the onset of liver development, in the differentiation of hepatic stem cell towards biliary epithelial cells, and in maintaining the morphological characteristic of biliary epithelial cells.