Demeilliers Christine, Jacquemin Emmanuel, Barbu Véronique, Mergey Martine, Paye François, Fouassier Laura, Chignard Nicolas, Housset Chantal, Lomri Nour-Eddine
Université de Cergy-Pontoise, GRP2H, Département de Biologie, Errmece, Cergy-Pontoise, France.
Hepatology. 2006 May;43(5):1125-34. doi: 10.1002/hep.21160.
Recent reports in patients with PFIC1 have indicated that a gene defect in ATP8B1 could cause deregulations in bile salt transporters through decreased expression and/or activity of FXR. This study aimed to: (1) define ATP8B1 expression in human hepatobiliary cell types, and (2) determine whether ATP8B1 defect affects gene expressions related to bile secretion in these cells. ATP8B1 expression was detected by RT-PCR in hepatocytes and cholangiocytes isolated from normal human liver and gallbladder. ATP8B1 mRNA levels were 20- and 200-fold higher in bile duct and gallbladder epithelial cells, respectively, than in hepatocytes. RT-PCR analyses of the liver from two patients with PFIC1, one with PFIC2, one with biliary atresia, showed that, compared to normal liver, hepatic expressions of FXR, SHP, CYP7A1, ASBT were decreased at least by 90% in all cholestatic disorders. In contrast, NTCP transcripts were less decreased (by < or = 30% vs. 97%) in PFIC1 as compared with other cholestatic disorders, while BSEP transcripts, in agreement with BSEP immunohistochemical signals, were normal or less decreased (by 50% vs. 97%). CFTR hepatic expression was decreased (by 80%), exclusively in PFIC1, while bile duct mass was not reduced, as ascertained by cytokeratin-19 immunolabeling. In Mz-ChA-2 human biliary epithelial cells, a significant decrease in CFTR expression was associated with ATP8B1 invalidation by siRNA. In conclusion, cholangiocytes are a major site ofATP8B1 hepatobiliary expression. A defect of ATP8B1 along with CFTR downregulation can impair the contribution of these cells to bile secretion, and potentially explain the extrahepatic cystic fibrosis-like manifestations that occur in PFIC1.
近期关于1型进行性家族性肝内胆汁淤积症（PFIC1）患者的报道表明，ATP8B1基因缺陷可通过法尼酯X受体（FXR）表达和/或活性降低导致胆汁盐转运体失调。本研究旨在：（1）确定ATP8B1在人肝胆细胞类型中的表达情况，以及（2）确定ATP8B1缺陷是否影响这些细胞中与胆汁分泌相关的基因表达。通过逆转录聚合酶链反应（RT-PCR）检测从正常人肝脏和胆囊分离出的肝细胞和胆管细胞中的ATP8B1表达。ATP8B1信使核糖核酸（mRNA）水平在胆管和胆囊上皮细胞中分别比肝细胞高20倍和200倍。对两名PFIC1患者、一名PFIC2患者和一名胆道闭锁患者的肝脏进行RT-PCR分析，结果显示，与正常肝脏相比，在所有胆汁淤积性疾病中，FXR、小异二聚体伴侣蛋白（SHP）、细胞色素P450 7A1（CYP7A1）、顶端钠依赖性胆汁酸转运体（ASBT）的肝脏表达至少降低了90%。相比之下，与其他胆汁淤积性疾病相比，PFIC1中钠-牛磺胆酸共转运多肽（NTCP）转录本减少程度较小（降低≤30%，而其他疾病降低97%），而胆汁盐输出泵（BSEP）转录本与BSEP免疫组化信号一致，正常或减少程度较小（降低50%，而其他疾病降低97%）。囊性纤维化跨膜传导调节因子（CFTR）肝脏表达降低（降低80%），仅在PFIC1中出现，而通过细胞角蛋白-19免疫标记确定胆管质量未减少。在Mz-ChA-2人胆管上皮细胞中，CFTR表达显著降低与ATP8B1被小干扰RNA（siRNA）敲除有关。总之，胆管细胞是ATP8B1在肝胆表达的主要部位。ATP8B1缺陷以及CFTR下调可损害这些细胞对胆汁分泌的贡献，并可能解释PFIC1中出现的肝外囊性纤维化样表现。
