Burke Zoë D, Shen Chia-Ning, Ralphs Kate L, Tosh David
Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom.
J Cell Physiol. 2006 Jan;206(1):147-59. doi: 10.1002/jcp.20438.
We previously demonstrated that dexamethasone (Dex) induces the transdifferentiation (or conversion) of the pancreatic progenitor cell line AR42J-B13 (B13) to hepatocytes based on the expression of liver proteins. We have extended our original observations to determine: (1) the effects of Dex on pancreatic gene expression; (2) the time course of expression of liver enriched transcription factors during conversion from pancreatic to hepatic phenotype; (3) the functional potential of transdifferentiated hepatocytes; (4) the proliferative capacity of transdifferentiated hepatocytes; and (5) whether ectopic expression of transcription factors can induce the hepatic phenotype in pancreatic B13 cells. The results were as follows. The B13 cell markers amylase, synaptophysin, and neurofilament were lost in transdifferentiated hepatocytes compared to control cells and the liver enriched transcription factors C/EBPbeta and C/EBPalpha were induced first, followed by HNF4alpha and then RXRalpha. Using RT-PCR analysis and immunolocalisation studies, we detected hepatic markers (e.g., apolipoprotein B) in Dex-treated cells. In transdifferentiated hepatocytes albumin was secreted, insulin stimulated lipid deposition and ciprofibrate enhanced the expression of catalase. Proliferation of transdifferentiated hepatocytes is promoted in the presence of HGF and NEAA as indicated by the co-expression of the cell cycle markers cyclin D and phosphohistone H3 with liver proteins. Lastly, ectopic expression of C/EBPalpha or C/EBPbeta in AR42J-B13 cells was sufficient to induce transdifferentiation, based on nuclear localization of HNF4alpha and induction of UDP-glucuronosyltransferase expression. These results indicate that the B13 progenitor cell model is suitable for studying liver function and for understanding the molecular and cellular events that occur during transdifferentiation.
我们之前证实，基于肝脏蛋白的表达，地塞米松（Dex）可诱导胰腺祖细胞系AR42J-B13（B13）转分化（或转变）为肝细胞。我们扩展了最初的观察结果，以确定：（1）Dex对胰腺基因表达的影响；（2）从胰腺表型转变为肝表型过程中肝脏富集转录因子的表达时间进程；（3）转分化肝细胞的功能潜力；（4）转分化肝细胞的增殖能力；以及（5）转录因子的异位表达是否能在胰腺B13细胞中诱导肝表型。结果如下。与对照细胞相比，转分化肝细胞中B13细胞标志物淀粉酶、突触素和神经丝消失，肝脏富集转录因子C/EBPβ和C/EBPα首先被诱导，随后是HNF4α，然后是RXRα。通过逆转录聚合酶链反应（RT-PCR）分析和免疫定位研究，我们在Dex处理的细胞中检测到了肝脏标志物（如载脂蛋白B）。转分化肝细胞分泌白蛋白，胰岛素刺激脂质沉积，环丙贝特增强过氧化氢酶的表达。如细胞周期标志物细胞周期蛋白D和磷酸化组蛋白H3与肝脏蛋白的共表达所示，在肝细胞生长因子（HGF）和非必需氨基酸（NEAA）存在的情况下，转分化肝细胞的增殖得到促进。最后，基于HNF4α的核定位和UDP-葡萄糖醛酸基转移酶表达的诱导，AR42J-B13细胞中C/EBPα或C/EBPβ的异位表达足以诱导转分化。这些结果表明，B13祖细胞模型适用于研究肝功能以及理解转分化过程中发生的分子和细胞事件。
